31 MILLER CONFERENCE ON RADIATION CHEMISTRY …...31st MILLER CONFERENCE ON RADIATION CHEMISTRY...

31st MILLER CONFERENCE ON RADIATION CHEMISTRY

September 9-14, 2019, Energus, Workington

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TUESDAY 10th SEPTEMBER

08:00 Sunrise Session - Fundamentals, David Grills and Matt Bird

09:00

09:35

10:00

10:35

Fundamentals-I Session (pulsed) Chair - David Grills

I1: “Time-Resolved Resonance Raman Studies of Pulse Radiolytic Reactions”

Ireneusz Janik

I2: “Partial Molar Volume of the Hydrated Electron and a Comment on Its

Vertical Detachment Energy” Dave Bartels

P1: “Chemical Dosimetry of Femtosecond Electron Bunches Provided by Laser-

Plasma Acceleration” Gerald Baldacchino

P2: “Femtosecond Resolution for Picosecond Radiolysis Using Electron Pump-

Repump-Probe Spectroscopy” Sergey Denisov

11:00 Coffee

11:20

11:55

12:30

12:55

Fundamentals-II Session (other) Chair - Jim Wishart

I3: “Simulation of Radiation Damage Processes” Andrey Solov’yov

I4: “Mimicking Oxidative Stress by Radiation Biochemistry. Addition of Free

Radicals to a Free Radical Producer: NADPH Oxidase” Chantal Houée-Levin

P3: “Molecular Simulations of the Oxidative Radiolysis of two Inverse Peptides:

Methionine Valine and Valine Methionine” Pierre Archirel

P4: “Comprehensive Model for X-Ray Induced Damage in Protein

Crystallography” David Close

13:20 Free Time

16:30

16:45

17:00

17:15

17:30

17.45

Pre-Poster Talks Session, Chairs Fred Currell and Mats Jonsson

PP1: “Impact of Doping and Functionalisation of Graphene Support on the

Radiolytic Synthesis of Palladium Nanoparticles for Electrocatalysis” Kun Guo

PP2: “Role of Electronic Energy Loss of the Ion Beam in the Modification of

Graphene Oxide Film” Chetna Tyagi

PP3: “Radiation Induced Polymerization of Nanostructured Conducting

Polymers” Teseer Bahry

PP4: “Effect of Surface Deformation on Stress Corrosion Crack Initiation in

Austenitic Stainless Steels in PWR Primary Water” Litao Chang

PP5: “Method of Assessing the Radiation Tolerance of Commercial Strippable

Coatings” Alex Jenkins

PP6: “Studying Nascent Proton-Driven Radiation Chemistry in H2O in Real Time

Using Laser-Based Sources” Mark Coughlan

18:00 Poster Session 1 (even numbers)

19:00 Coaches for Cockermouth



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I1: Time-Resolved Resonance Raman Studies of Pulse Radiolytic Reactions

I. Janik

Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA

Time resolved Resonance Raman spectroscopy is a powerful structure-sensitive technique for

detection, identification and determination of bond-properties and reactive behavior of short-

lived chemical species in solution. The Notre Dame Radiation Laboratory has been the leading

laboratory worldwide in the application of this novel vibrational spectroscopic technique to the

reaction intermediates produced on pulse radiolysis. The recent innovations in our

experimental setup have been to reduce the overall volume of the solutions on which the

transient Raman studies can be performed, and the improvement on the collection optics that

increased the detection sensitivity by orders of magnitude. These improvements have

facilitated the Raman observation of weakly absorbing reaction intermediates with low

resonance Raman enhancement. Vibrational signatures of a number of key intermediates

absorbing in the range from deep ultraviolet (UV) to visible range have been characterized for

the first time. Measurements of the Raman frequencies, their shifts from the gas-phase to

aqueous solution, and the Raman bandwidths provide an insight into the bond properties of the

radicals and the radical water interactions. Determination of harmonic frequencies and

anharmonicity constants have allowed us to estimate the bond dissociation energies in several

pseudo-diatomic systems. The structural determinations in a few instances have been used to

develop a molecular perspective on the thermochemistry in an aqueous environment for the

first time. In the case of a few negatively charged intermediates vibrational footprint of their

interaction with the hydration cage have been also detected for the first time. Vibrational

studies of a few representative class of reactive intermediates will be presented. In particular,

the UV absorbing species like O2- and CO2

- 1,2 , and the hemi-bonded species, e.g., (SCN)2-,3,4

and also a few OH adducts5 will be discussed in some detail.

References

1. Janik, I. and Tripathi, GNR. (2013) The Nature of the Superoxide Radical Anion in Water, J. Chem.

Phys 139, 014302

2. Janik I., and Tripathi G.N.R. (2016) The nature of CO2- radical anion in water, J. Chem. Phys. 144,

154307

3. Janik, I., Carmichael, I., Tripathi, G.N.R., (2017) Transient Raman spectra, structure and

thermochemistry of the thiocyanate dimer radical anion in water, J. Chem. Phys., 146, 214305

4. Janik, I., and Tripathi, G.N.R., (2019) The selenocyanate dimer radical anion in water: Transient

Raman spectra, structure, and reaction dynamics, J. Chem. Phys., 150, 094304

5. Janik, I., and Tripathi, G.N.R., (2013) The early events in the OH radical oxidation of dimethyl sulfide in water, J. Chem. Phys. 138, 25.



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I2: Partial Molar Volume of the Hydrated Electron and a Comment on Its

Vertical Detachment Energy

Ireneusz Janik, Alexandra Lisovskaya and David M. Bartels

Notre Dame Radiation Laboratory, Notre Dame University, Notre Dame, Indiana, USA.

The partial molar volume of the hydrated electron was investigated with pulse radiolysis and

transient absorption2 by measuring pressure-dependence of the equilibrium constant for e-aq +

NH4+ H + NH3 . At 2 kbar pressure the equilibrium constant decreases relative to 1 bar

by only 6%. Using tabulated molar volumes for ammonia and ammonium, we have the result

V(e-aq) – V(H) = 11.3 cm3/mol at 25oC, confirming that V(e-aq) is positive and even larger than

the hydrophobic H atom. Assuming the molar volume of H atom is somewhat less than that of

H2, we estimate V(e-aq ) = 26±6 cm3/mol. The positive molar volume is consistent with an

electron that exists largely in a small solvent void, ruling out a recent controversial model of

Larsen, Glover and Schwartz3 (LGS) that suggests a non-cavity structure with negative molar

volume. It is suggested that no one-electron pseudopotential model of the hydrated electron is

likely to capture all of the dynamical properties of this species that depend on details of the

wavefunction. A full ab initio MD approach may be necessary.

A recent paper of Luckhaus, et al1 has presented

photoelectron data and analysis of eleven liquid

microjet experiments with various excitation

wavelengths from 3.6 to 5.8 eV to extract a

“genuine” distribution of vertical electron

binding energies for the hydrated electron (Figure

1). The analysis involves correction of the

individual photoelectron energy distributions at

each wavelength for scattering losses in the liquid

before escape into the vacuum. Surprisingly the

distribution reported is bimodal, resembling two

overlapping Gaussians with centers at 3.5 and 4.5

eV. We find the bimodal distribution highly

implausible, as it represents a gross violation of

linear response for the hydrated electron ground

state energy. Rather, we identify a flaw in the

calculation of scattering losses that leads to the

bimodal distribution. The “bottom of the

conduction band” in liquid water has been taken

to be Vo = -1.0 eV relative to the vacuum. In the

scattering model used, electrons with kinetic

energies below 1.0 eV never escape from the

liquid microjet. This assumption is shown to be inconsistent with the data being fitted, and a

more likely number is Vo = -0.1 ± 0.1 eV.

References

1. Luckhaus, D.; Yamamoto, Y. I.; Suzuki, T.; Signorell, R. Genuine Binding Energy of the Hydrated

Electron. Science Advances 2017, 3 (4).

2. Janik, I.; Lisovskaya, A.; Bartels, D. M. Partial Molar Volume of the Hydrated Electron. Journal of Physical Chemistry Letters 2019, 10 (9), 2220-2226.

3. Larsen, R. E.; Glover, W. J.; Schwartz, B. J. Does the Hydrated Electron Occupy a Cavity? Science

2010, 329 (5987), 65-69.

Figure 1. “Genuine” electron Binding

Energy (eBE(g)) distribution reported by

Luckhaus, et al.1 The bimodal

distribution (asterisks) with average of

3.7eV can be decomposed into a pair of

Gaussian functions centered at ca. 3.5

and 4.5 eV.



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P1: Chemical Dosimetry of Femtosecond Electron Bunches Provided by

Laser-Plasma Acceleration

Gérard Baldacchino, Houda Kacem, Pierre Forestier-Colleoni, Jean Daniel Ahui, Tiberio

Ceccotti, Sandrine Dobosz Dufrénoy

LIDYL, UMR9222 CEA CNRS, Université Paris-Saclay, 91191 Gif-sur-Yvette, France.

The radiobiological effects of the recent protocol in radiotherapy named FLASH seem to be in

relation with the dose rate effect of µs electron pulses. Actually, it spares healthy tissues and

damages tumor cells in a radiotherapy utilization, which improves the treatment prognostic

compared to conventional radiotherapy [1]. This effect could be enhanced by using a higher

dose rate provided by femtosecond electron pulses generated by laser-plasma accelerator. In

this framework, we have studied the chemical effect associated to electron pulses as short as a

few femtoseconds which are provided by high intensity laser (1018 W/cm2) in interaction with

a gas mixture of 99%H2+1%N2.. In these conditions, we expect to produce ultimate dose rates

of electrons in the range of the TGy/s (ie: 1012 Gy.s-1). Their energy belongs to the range 20-

100 MeV. In order to evaluate the dose rate effect in liquid water by chemical fashion, the

determination of radiolytic yields (G-values) of radicals and molecules such as hydrated

electron, hydroxyl radical and hydrogen

peroxide is mandatory. As G-value is the limit

value at dose = 0 of C/d, we first determined

the doses d by simulation using GEANT4

program and electron counting at every shot.

Then, we have used fluorescence spectroscopy

for measuring sensitively the concentrations C

of the above-mentioned species. Then the

scavenging method using Resazurin and

Ampliflu Red as described in ref [2] gives G-

values determination as depicted in figure 1.

The comparison with G-values obtained under

-rays were performed. We will show that

electrons bunches provided by the UHI100

installation at Saclay [3] have produced a small

dose rate effect because hydrated electron and hydroxyl radical have G-values 0.026 and 0.023

µmol.J-1 respectively. H2O2 one seems increased. It will be discussed as well. As these yields

account for the species escaped from recombination in the spurs, molecules could be then

favored because they are the result of radical-radical reactions.

References

1. Favaudon, V., Fouillade, C., Vozenin, M.C. (2015) Ultra-high dose-rate, "flash" irradiation

minimizes the side effects of radiotherapy. Cancer Radiothérapie. 19, 526-531.

2. Baldacchino, G., Brun, E., Denden, I., Bouhadoun, S., Roux, R., Khodja, H., Sicard-Roselli, C.

(2019) Importance of radiolytic reactions during high‑LET irradiation modalities: LET effect, role of

O2 and radiosensitization by nanoparticles. 10, 1-21.

3. Maitrallain, A., Audet, T.L., Dobosz Dufrénoy, S., Chancé, A., Maynard, G., Lee, P., Mosnier, A.,

Schwindling, J., Delferrière, O., Delerue N, Specka, A., Monot, P., Cros, B. (2018) Transport and

analysis of electron beams from a laser wakefield accelerator in the 100 MeV energy range with a

dedicated magnetic line NIMA: Accelerators, Spectrometers, Detectors and Associated Equipment.

908,159-166.

Figure 1. Resorufin (RN) concentration as a

function of the dose delivered by electron bunches

@ UHI100 installation. Slope at d=0 gives the G-

value of OH, here under N2O bubbling.



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P2: Femtosecond Resolution for Picosecond Radiolysis Using Electron

Pump-Repump-Probe Spectroscopy

S.A. Denisov and M. Mostafavi

Laboratory of chemical physics UMR8000/CNRS, Université Paris-Saclay, Orsay, France

For decades electron picosecond radiolysis

set-ups remain workhorses of fast time-

resolved radical chemistry despite presence

of subpicosecond electron accelerators.

The list of systems where later could be

applicable is rather short despite high

efficient doses, due to the effect of the

group velocity mismatch of the electron

and the light in the sample what limits

samples length to sub-mm paths [1].

Meanwhile the concentration (manifested

in optical density) of produced radicals is a

crucial issue for radiolysis studies in sub-

and picosecond regimes.

In our work, the newly implemented

technique of 3 pulse electron pump (5 ps) –

optical repump by laser (110 fs) and probe by

with light (150 fs) on the ELYSE platform

(Université Paris-Saclay, Orsay) will be

discussed in details. This technique

reinforces existing platform by opening new

research fields earlier inaccessible due to

time-resolution issues of electron

accelerator.

The electron solvation mechanism in water and other solvents will be revisited. Along with

that, perspective experiments accessible to three pulse spectroscopy will be discussed,

revealing research fields, e.g., dissociative electron attachment in liquids previously directly

unreachable for existing time-resolved radiolysis experimental set-ups limitations [2-3].

Reference(s) 1. Yang, J.; Kan, K.; Kondoh, T.; Yoshida, Y.; Tanimura, K. and Urakawa, J. Femtosecond pulse

radiolysis and femtosecond electron diffraction. Nucl Inst Methods Phys Res A 2011, 637, 24–33

2. Ma, J.; Wang, F.; Denisov. S.A.; Adhikary, A. and Mostafavi, M. Reactivity of prehydrated

electrons toward nucleobases and nucleotides in aqueous solution. Sci Adv 2017, 3, e1701669

3. Ma, J.; Kumar, A.; Muroya, Y.; Yamashita, S.; Sakurai, T.; Denisov, S.A.; Sevilla, M.D.;

Adhikary, A.; Seki, S. and Mostafavi, M. Observation of dissociative quasi-free electron attachment

to nucleoside via excited anion radical in solution. Nat Commun. 2019, 10, 102.

Figure 1. Optical density evolution of

solvated electron signal @620 nm,

@1200 nm excited by repump (780 nm) pulse

after passage of 5 ps electron pulse.

Relaxation of the transient signals occurs after

less than 270 fs, corresponding to the

transition from p state to the s-like state.



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I3: Simulation of Radiation Damage Processes

A.V. Solov’yov

MBN Research Center, Altenhöferallee 3, 60438 Frankfurt am Main, Germany

The multiscale modeling of complex molecular systems is a hot topic of the modern theoretical

and computational research. Radiation damage is one of the exemplar topics in which the

multiscale approach is required for the understanding of the whole cascade of physico-

chemical, and sometimes even biological processes, that are behind the damages caused by

radiation in various targets [1, 2, 3]. To fully understand the dynamics of irradiated molecular

systems and exploit this knowledge in different technological applications, such as X-rays and

hadron therapy, radioprotection, surface deposition and nanofabrication technologies,

construction of novel light and energy sources, and others, one needs to consult many

disciplines ranging from physics and chemistry to materials and life sciences, software

engineering and high performance computing.

The recent advances in this research area have been achieved due to understanding of the

physical and chemical effects that involve different temporal and spatial scales. Illustrative

examples of such effects concern the ion-induced shock waves [4,5], radiation chemistry in the

vicinity of ion tracks [6], creation of complex irreversible damages in materials and biological

systems [1-3]. Molecular level understanding of these and many other processes can be

achieved by means of irradiation driven molecular dynamics (IDMD) [7], a powerful novel

multiscale computational technique implemented in professional software packages MBN

Explorer [1,8] and MBN Studio [1,9] enabling efficient computational studies of a broad range

of collision and irradiation driven processes involving numerous MesoBioNano systems.

The talk will give an overview of recent advances in the field of radiation damage which are

based on the multiscale approach. It will highlight a number of recent case studies that have

been performed by means of IDMD, MBN Explorer and MBN Studio.

References

[1] I.A. Solov’yov, A.V. Korol, A.V. Solov'yov, Multiscale Modeling of Complex Molecular Structure

and Dynamics with MBN Explorer, Springer International Publishing AG (2017), Cham, Switzerland,

451 pp.

[2] A.V. Solov’yov (ed.), Nanoscale Insights into Ion-Beam Cancer Therapy, Springer International

Publishing, Cham, Switzerland (2017), 498 pp.; E. Surdutovich, A.V. Solov'yov, Colloquium Paper,

Eur. Phys. J. D 68, 353 (2014)

[3] A. Verkhovtsev, E. Surdutovich, A.V. Solov'yov, Cancer Nanotechnology 10, 4 (2019)

[4] E. Surdutovich, A.V. Solov’yov, Phys. Rev. E 82, 051915 (2010)

[5] P. de Vera, E. Surdutovich, A.V. Solov'yov, Cancer Nanotechnology 10, 5 (2019)

[6 ] P. de Vera, E. Surdutovich, N.J. Mason, F.J. Currell, A.V. Solov'yov, Eur. Phys. J. D 72, 147 (2018)

[7] G.B. Sushko, I.A. Solov'yov, A.V. Solov'yov, Eur. Phys. J. D 70, 217 (2016)

[8] I.A. Solov’yov, A.V. Yakubovich, P.V. Nikolaev, I. Volkovets, A.V. Solov’yov, J. Comput. Chem.

33, 2412 (2012); www.mbnresearch.com; wikipedia.org/wiki/MBN_Explorer

[9] G.B.Sushko, I.A. Solov'yov, A.V. Solov'yov, J. Mol. Graph. Model., 88, 247 (2019)



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I4: Mimicking Oxidative Stress by Radiation Biochemistry. Addition of

Free Radicals to a Free Radical Producer: NADPH Oxidase Stephenson Boayke Owusu, Laura Baciou, Tania Bizouarn, Chantal Houée Levin

Laboratoire de Chimie Physique. Univ. Paris Sud, Univ. Paris Saclay, CNRS UMR8000, 91405 Orsay France

Radiation biochemistry is a useful tool to mimic oxidative stress involved in the evolution of

all diseases with the advantage of being quantitative. One can study the free radical induced

processes of biomolecules. Moreover, one may enlighten new processes important for the

development of diseases.

Oxygen free radicals (reactive oxygen species, ROS) are also produced in vivo independently

of radiations. We are currently investigating the regulation of their production in neutrophils,

i.e. polynuclear white blood cells. They are capital for the destruction of pathogens, but also

noxious. Their production is due to a ubiquitous enzyme, NADPH oxidase, that delivers

superoxide anions in cells. In phagocytes, it is constituted by the assembly of at least four

cytosolic and two membrane proteins. This enzyme needs activation to produce superoxide

free radicals. In vitro, it is done by addition of arachidonic acid.

Our present interest is the regulation by free radicals themselves, that modify proteins and

hence their biological roles. We used gamma and pulse radiolysis to produce O2•- and •OH

radicals. In a cell-free system, we showed previously that during its assembly, the system

passes through sub-states of different sensitivities1. The regulatory activity of each protein

varies with their oxidation state and some of the important modifications were identified.

When human neutrophils are irradiated, very different processes take place. The NADPH

oxidase retains a basal activity after irradiation even in the absence of activator. The amount of

enzyme per cell increases slightly with the dose, like that of the total membrane proteins. In

addition, some cytosolic proteins are found at the membrane. Taken together these facts would

indicate a very low activation by free radicals.

1. Ostuni, M. A.; Gelinotte, M.; Bizouarn, T.; Baciou, L.; Houee-Levin, C., Targeting NADPH-

oxidase by reactive oxygen species reveals an initial sensitive step in the assembly process. Free

Radic Biol Med 2010, 49 (5), 900-7.



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P3: Molecular Simulations of the Oxidative Radiolysis of two Inverse

Peptides: Methionine Valine and Valine Methionine

P. Archirel, Ch. Houée-Lévin and J. L. Marignier

Laboratoire de Chimie Physique, Université Paris-Sud, 91405 Orsay, France

Oxidative radiolysis of the peptides has been performed at the Elyse facility of the LCP. The

two peptides undergo very different processes, as can be seen on the absorption spectra

recorded at different times and concentrations. We have also performed molecular simulations,

in order to interpret these spectra. Our method associates Monte-Carlo sampling of the nuclear

configurations, DFT and TDDFT calculations of the electronic structure and PCM simulation

of the solvent [1,2]. The results enable a fine understanding of the two species:

1. Met-Val displays a main band at 390 nm and no concentration effect. This is due to the

H atom uptake leaving a neutral radical Met-Val (-H) stabilized by a (2c-3e) SN bond.

This species is very stable and undergoes no bimolecular reaction with neutrals.

2. Val-Met displays a complex spectrum with at least three species, see figure 1, left, and

a striking concentration effect. The three species are plausibly a Val-Met (-H) radical

at high energy (285 nm), the Val-Met+ cation, stabilized by a (2c-3e) SO bond at middle

energy (367 nm) and a (Val-Met)2+ dimer cation, stabilized by a (2c-3e) SS bond, at

lower energy (540 nm), see figure 1, right. This last species can be formed either by

direct oxidation of neutral dimers present in solution, and by bimolecular dimerization

of cation monomers. This last species has not been simulated, but can be inferred from

simulations of the Met2+ cation [3].

Figure 1 Oxidative radiolysis of Val-Met: measured (left) and simulated spectra (right) of a

neutral radical (black curve), the cation (red curve) and the dimer (green curve)

References

1. Gaussian 09 RevD01 Gaussian Inc. Wallingford CT, 2013

2. Wang, F. Horne, G. Pernot, P. Archirel, P. and Mostafavi, M. J. Phys. Chem. B 122 (2018), 7134-

7142

3. Archirel, P. Bergès J. and Houée-Lévin, Ch. J. Phys. Chem. B 120 (2016), 9875-9886



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P4: Comprehensive Model for X-Ray Induced Damage in Protein

Crystallography

D. Close, W. Bernhard

Acquisition of X-ray crystallographic data is always accompanied by structural degradation

due to the absorption of energy. The application of high fluency X-ray sources to large

biomolecules has increased the importance of finding ways to curtail the onset of X-ray induced

damage. A significant effort has been underway with the aim of identifying strategies for

protecting protein structure. A comprehensive model is presented that has the potential of

explaining, both qualitatively and quantitatively, structural changes induced in crystalline

protein at ~100 K. The first step is to consider the qualitative question, what are the radiation

induced intermediates and expected end products? The aim of this presentation is to assist in

optimizing these strategies through a fundamental understanding of radiation physics and

chemistry with additional insight provided by theoretical calculations performed on the many

schemes presented.



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PP1: Impact of Doping and Functionalisation of Graphene Support on the

Radiolytic Synthesis of Palladium Nanoparticles for Electrocatalysis

Kun Guo1,2 and Aliaksandr Baidak1,2

1School of Chemistry, The University of Manchester, Manchester M13 9PL, UK; 2Dalton Cumbrian Facility, The University of Manchester, Moor Row CA24 3HA, UK.

Gamma radiolysis of common solvents, including ethylene glycol, is known to generate strong

reducing species such as solvated electron, hydrogen atom and carbon-centred radicals. This

mechanism provides a green and facile route to synthesize colloidal metal nanoparticles (NPs)

immobilized on graphene-based supports. However, controlling the NP size and size

distribution remain challenging. Hereby we investigate the impact of heteroatom doping and

functionalisation of graphene-based supports on tackling such challenges. Four types of

graphene materials, namely graphene oxide (GO), reduced graphene oxide (rGO), graphene

(G), and nitrogen-doped graphene (N-G), are utilised to immobilize palladium (Pd) NPs, which

are obtained by γ-radiation-induced reduction in ethylene glycol. The as-prepared composites

are then evaluated in the electrocatalytic hydrogen evolution reaction (HER).

For the same Pd NP loading, N-G is found to be the best support to achieve the smallest

overpotential (difference between the applied and theoretical potentials) and the highest

catalytic activity, as shown in Figure 1a. The overpotential at a current density of 10 mA

cm−2 (η10) on Pd/N-G is 160 mV smaller than that on Pd/rGO. Tafel analysis derived from the

polarizaiton curves shows that Pd/N-G has a Tafel slope of 101 mV decade−1, indicating the

rate determining step of HER on Pd/N-G is the Volmer step (H3O++e−+ * ⇄H*+H2O, where

* denotes the active site). The activity difference of four composites should be ascribed to the

NP size and size distribution of Pd NPs anchored onto these supports. NP size is well-

documented to strongly affect the catalytic activity/selectivity because more surface active

sites are exposed as size decreases. N-G is thus

reasoned to gain the smallest Pd NP size and best

size distribution during the radiolytic synthesis,

which should be correlated to the positive role of

doped N atoms in stabilising the formed NPs.

Given the positive role of doped N atoms, we

further prepare N-G supported with four loadings

of Pd NPs to explore the potential threshold in

maintaining the Pd NP size. Figure 1b presents the

polarization curves of N-G loaded with 1.3~5.2 wt.

% Pd NPs and the benchmark Pt/C catalyst. The

best performance of Pt/C accords well with the

literature. In contrast, the η10 and Tafel slope are

found to be the smallest for 2.6 wt. % Pd/N-G,

indicating its highest HER catalytic activity. The

decreased activity of 3.9 and 5.2 wt. % Pd/N-G

should be attributed to the severe aggregation of

Pd NPs, leading to lower atom efficiency.

Therefore, in order to achieve a desirable NP size

and size distribution, the NP loading shall be

carefully controlled.

Figure 1. Polarization curves of Pd NPs

supported on four graphene-based supports

(a) and Pd NPs supported on N-G with four

loadings (b) in 0.5 M H2SO4.



12

PP2: Role of Electronic Energy Loss of the Ion Beam in the Modification of

Graphene Oxide Film

Chetna Tyagi1,2, A. Tripathi2 and D. K. Avasthi3

1Dalton Cumbrian Facility, The University of Manchester, Cumbria, UK, 2Inter-University Accelerator Centre, New Delhi, India,

3Amity Institute of Nanotechnology, Amity University, Noida, India.

Ion beam irradiation is a clean method to produce desired modifications in materials in a

controlled manner [1]. The present work shows the modifications induced in graphene oxide

film under swift heavy ion irradiation with different electronic energy loss. Graphene oxide

films were irradiated with Gold ion beam having energy 120 MeV with fluences varying from

3×1010 ions/cm2 to 1×1013 ions/cm2. X-ray diffraction and spectroscopic techniques indicated

some annealing effect induced by ion beam at lower fluences of irradiation while signature of

carbyne could be seen in Raman spectroscopy at higher fluence (Figure 1). Similarly, Carbon

beam of energy 80 MeV with relatively low electronic energy loss was used to irradiate the

graphene oxide films with different fluences. Different characterization techniques showed the

creation of defects by ion beam in the films. Theoretical simulations showed the local lattice

temperature raised in the films when irradiated with ion beams having different energy loss. It

could be seen that ion beam having high electronic energy loss could raise the temperature of

the film above its annealing and melting temperature, resulting in two competing phenomena:

annealing and amorphization. Also, the estimated radius of the ion track (core and halo region)

formed by Gold ions irradiation was calculated experimentally and compared with the

theoretical values obtained by simulation.

(a) (b)

Figure 1. (a) Plot showing the intensity of in-situ X-ray diffraction peak of pristine and

irradiated sample and (b) Raman spectra of irradiated sample with different fluence. Magnified

part is showing the origin of carbyne peak at high fluences.

Reference

1. GK Mehta, (1997) Swift heavy ions in Materials Science – emerging possibilities, Vacuum, 48, 957-

959.



13

PP3: Radiation Induced Polymerization of Nanostructured Conducting

Polymers

T. Bahry1 and S. Remita2

1Laboratoire de Chimie Physique, LCP, UMR 8000, CNRS, Université Paris-Sud 11, Bât. 349, Campus d’Orsay, 15 Avenue Jean Perrin, Orsay Cedex 91405, France

2Département Chimie Vivant Santé, Conservatoire National des Arts et Métiers, CNAM, 292 rue Saint-Martin, Paris Cedex 75141, France.

Conducting polymers (CPs) have gained vast attraction due to their unique optical and

electrical properties [1]. Thanks to these prominent and extraordinary properties, CPs have

been used in several fields and integrated in many applications [2]. Tremendous efforts have

been made to develop and upgrade the synthesis methodologies of CPs [3]. Apart from

traditional methods of polymers synthesis, ionizing radiation induced polymerization by -rays

without using oxidizing agents appears to be alternative and easy way to produce conducting

polymers. Indeed, our group has developed a new methodology based on radiation chemistry

to polymerize some of those conducting polymers (CPs) in aqueous solutions [4, 5]. Recently,

we extended this methodology to the synthesis of CPs in organic solvent [6]. In this context,

we succeeded in the oxidative polymerization of different classes of thiophene derivatives

monomers dissolved in dichloromethane by means of gamma-radiolysis (Figure 1). The

spectroscopic analysis and microscopic observations manifest that the radio-synthesized

polymers in dichloromethane are characterized by interesting optical and electrical.

Reference(s)

1. A. J. Heeger, J. Phys. Chem. 2001, 105 (36), 8476-8491.

2. R. Balint, et al., Acta Biomater. 2014, 10(6), 2341-53.

3. X. T. Zhang, et al., J. Phys. Chem. 2006, (110), 1158−1165.

4. Y. Lattach, et al., Radiat. Phys. Chem. 2013, (82), 44-53.

5. Z. P. Cui, et al., Langmuir. 2014, (30), 14086−14094.

6. T. Bahry et al., New J. Chem. 2018, 42 (11), 8704-8716.1.

Figure 1. PEDOT, P3HT and P3TAA synthesized by gamma radiolysis in

dichloromethane



14

PP4: Effect of Surface Deformation on Stress Corrosion Crack Initiation in

Austenitic Stainless Steels in PWR Primary Water

Litao Chang, M. Grace Burke, Fabio Scenini

Materials Performance Center, The University of Manchester, Manchester, UK M13 9PL

Austenitic stainless steels are widely used in the nuclear power plants due to their good general

corrosion resistance to the high temperature aqueous environment. However, they can suffer

from environmentally-assisted degradation problems, such as stress corrosion cracking (SCC),

during the long-term exposure to the environment. Numerous researches indicate that cold-

work, induced either intentionally or incidentally, is necessary for SCC in austenitic stainless

steels in PWR primary water. In the present study, the effect of the machining-induced surface

deformation on SCC initiation of austenitic stainless steels in PWR primary water has been

investigated through accelerated slow strain rate tensile tests and microstructural

characterization. The results showed that machining always introduced a deformation layer to

the steels. This layer is characterized by an ultrafine-grained outer layer and a highly deformed

inner layer consisted of twins and dislocations. SSRT test results showed that machining

significantly reduced the SCC initiation susceptibility of the cold-worked material as a reduced

number of cracks were identified in the machined surface compared to the polished surface.

The results also indicated that a low temperature heat treatment could further increase the SCC

initiation resistance of the machined surface because of the recovery which happened with the

ultrafine-grain. The associated mechanisms and possible implications of the results have been

discussed.

Reference(s)

1. Chang et al., Stress corrosion crack initiation in machined type 316L austenitic stainless steel in

simulated pressurized water reactor primary water, Corr. Sci. (2018) 138, 54-65

2. Chang et al., Effect of machining on stress corrosion crack initiation in warm-forged type 304L

stainless steel in high temperature water, Acta Mater. (2019)165, 203-214

3. Chang et al., Understanding the effect of surface finish on stress corrosion crack initiation in warm-

forged stainless steel 304L in high-temperature water, Scripta Mater. (2019) 164, 1-5



15

PP5: Method of Assessing the Radiation Tolerance of Commercial

Strippable Coatings

A. Jenkins1, L. Ostle1, T. Donoclift2, R. Edge2, T. Unsworth2, K. Warren2

1 Sellafield Ltd., Seascale, Cumbria. UK

2Dalton Cumbrian Facility, The University of Manchester, Westlakes Science Park, Moor Row,

Cumbria. UK

There are a plethora of commercially available strippable coating products, designed for

contamination control and decontamination purposes. Sellafield Ltd. has sought for a number

of these to be subjected to a predefined series of analyses pre and post irradiation to observe

any degradation of the product. Irradiation of the coatings to doses of 500kGy was separately

carried out by cobalt-60 and ion-beam to mimic plutonium alpha particles by Dalton Cumbrian

Facility. This dose threshold was deemed sufficient to allow for wastes to be packaged and

reach the respective disposal point.

A series of analyses were carried out and comparisons made of the pre and post irradiation.

The analyses included; direct observations for physical colour changes and deformities,

scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR),

Raman spectroscopy, Gas Chromatography – Mass Spectroscopy (GC-MS) and energy-

dispersive X-ray spectroscopy (EDS).

An illustration of how these coating systems degrade will be given alongside more anecdotal

perspective of how more easily obtained gamma irradiation can be used to infer alpha

degradation of organic species.



16

PP6: Studying Nascent Proton-Driven Radiation Chemistry in H2O in Real

Time Using Laser-Based Sources

M. Coughlan1*, N. Breslin1, M. Yeung1

, H. Donnelly1, C. Arthur1, L.Senje2, M. Taylor1, G.

Nersisyan1, D. Jung1, M. Zepf2 and B. Dromey1

1Department of Physics and Astronomy, Queen’s University Belfast, Belfast, United Kingdom 2Helmholtz-Institut Jena, D-07743 Jena, Germany

*[email protected]

Understanding the effects of ion interactions in condensed matter has been a focus of research

for decades. While many of these studies focus on the longer term effects such as cell death or

material integrity, typically this is performed using relatively long (>100 ps) proton pulses from

radiofrequency accelerators in conjunction with chemical scavenging techniques [1].

As protons traverse a material, they generate tracks of ionisation that evolve rapidly on

femtosecond timescales. Recently, measurements of few-picosecond pulses of laser driven

protons have been performed via observation of transient opacity induced in SiO2 with sub-

picosecond resolution [2]. Here we present results showing a dramatic difference in the

solvation of electrons generated due to the interaction of relativistic electrons/X-rays and

protons in liquid water. The role of ionisation tracks and subsequent formation of nanoscale

cavities in water on the extended recovery time is discussed.

References

[1] G. Baldacchino, Radiation Physics and Chemistry, 77, 1218-1223 (2008). [2] B.Dromey, et al. Nature Communications, 7, 10642

mailto:*[email protected]



17

WEDNESDAY 11th SEPTEMBER

08:00 Sunrise Session - Heterogeneous, Simon Pimblott

09:00

09:35

10:10

10:35

Heterogeneous–I Session, Chair - Simon Pimblott

I5: “H2 and H2O Production from Water and Alumina” Jay LaVerne

I6: “Radiolytic Formation of H2O: The Elucidation of the H2/O2 Recombination

Mechanism” Darryl Messer

P5: “Electron Irradiation Treatment of Nanodiamonds” Christian Laube

P6: “Hydrogen Production by Steel Anoxic Corrosion under Gamma Irradiation”

Lina Giannakandropoulou

11:00 Coffee

11:20

11:55

12:30

Heterogeneous–II Session, Chair - Jay LaVerne

I7: “Radiolytic Hydrogen Production in Oxide and Hydroxide Sludges” Mel

O’Leary

I8: “Radiation-Induced Chemistry on Polymer-Liquid Interfaces and Diffusive

Behaviour of H2” Aliaksandr Baidak

P7:“Radiolytic Degradation of an Extractant for Actinides, HONTA — a

Comparative Study of Direct and Indirect Radiolysis Processes” Yuta Kumagai

13:00 Free Time

16:00 Poster Session 2 (odd numbers)

17:00

17:45

18:30

Industrial Hot Topics Session, Chair - Fred Currell

H1: “Research in Radiation Chemistry to Support the Safe Storage of Plutonium

on the Sellafield Site” Helen Steele

H2: “The Radiation Chemistry of Spent Nuclear Fuel Systems” Steve Walters

Panel discussion: Panel - Steve Walters, Helen Steele, Mats Jonsson, Robin Orr

19:00 Coaches for Cockermouth



18

I5: H2 and H2O Production from Water and Alumina

J. A. LaVerne

Radiation Laboratory and Department of Physics, University of Notre Dame, Notre Dame,

Indiana, USA 46556

The main stable products in the radiolysis of water are H2 and H2O2. Both of these compounds

have transient precursors that can be affected by the presence of a heterogeneous interface.

Energy, mass or charge transfer between the interface and the nearby water can lead to variation

in the yields of H2 and H2O2 from what is observed in the radiolysis of neat bulk water. While

H2 is relatively stable in most circumstances, H2O2 is well known to react with surfaces.

This presentation will discuss the radiolytic formation of H2 and H2O2 including some of our

most recent water radiolysis models. Heterogeneous interactions will focus on water – alumina

interfaces, with the latter chosen because of its importance in the nuclear power industry.

Comparisons of the production of H2 with alumina will be made with the many other water –

solid ceramic oxides that have been examined. The production of H2 from adsorbed water on

alumina and from water – alumina slurries will be presented. Both the changes in the water

chemistry and in the alumina surface will be shown to gain information on processes occurring

at the interface. H2O2 is much more tenuous to examine because of its often fast reactivity with

solid surfaces. Fortunately, the reaction of H2O2 with alumina is relatively slow with respect to

the time scale of the radiation experiments. Mechanisms for the production of H2O2 under

different radiolytic conditions in bulk water and with added alumina will be presented.



19

I6: Radiolytic Formation of H2O: The Elucidation of the H2/O2

Recombination Mechanism

D. Messer1, R. Orr2, Sven Koehler3, Andrew Horn4, Simon Pimblott5

1-Dalton Cumbrian Facility, Westlakes Science Park, Moor Row, Cumbria, CA24 3HA, UK;

2-National Nuclear Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG, UK 3-School of Science & the Environment, Manchester Metropolitan University, Chester St, Manchester,

M1 5GD, UK. 4-The University of Manchester, Chemistry Department, Manchester. M13 9PL, UK

5-Idaho National Laboratory, Idaho Falls, ID 83415, USA.

Currently, the majority of the UK’s PuO2 stockpile produced by the reprocessing of spent

nuclear fuel is stored at the Sellafield site. The production of H2 and O2 by radiolysis of H2O

adsorbed to the surface of PuO2 is a safety concern for the UK nuclear industry by means of

storage vessel pressurisation and the potential formation of flammable gas mixtures. Lack of

observation of storage canister pressurisation in industry suggests recombination between H2

and O2 occurring simultaneously to H2O radiolysis. Here, we have developed a kinetic model

for the 1-1-98 vol% H2-O2-Ar system which, alongside coinciding experimental studies, has

been used to elucidate a reaction mechanism of such recombination reactions.

The model shows close agreement to

experimental results, depicted in

Figure 1. We elucidate a two-step

process for H2/O2 recombination: a

primary pathway initiated by

excitation/ionisation of Ar;

following by a secondary, H2O-

catalysed pathway. This secondary

pathway forms reactive

intermediates by water-catalysed

reactions with H2, which then

proceed to produce further H2O. The

OH∙ radical is involved in all H2O

forming termination steps, and each

pathway initiates via the

excitation/ionisation of Ar.

Figure 2 - Comparison of experimental and computational

results for H2 consumption for the 1-1-98 %vol H2-O2-Ar -

irradiated system. Black = experimental results, Red = model

results



20

P5: Electron Irradiation Treatment of Nanodiamonds

C. Laube1, J.Zhou2, A.Kahnt1, W. Knolle1, Bernd Abel1

1Leibniz Institut of Surface Engineering, Leipzig, Germany, 2Helmholtz Centre of Environmental Research UFZ, Leipzig, Germany

Nanodiamonds (NDs) offer great potential on multiple fields of research such as medical and

sensory application. Herein, the tailoring of the ND surface functionalities and color center

formation inside the diamond lattice can be regarded as key factors for the suitability of the

NDs for these applications. Especially the efficient formation of NV color centers lies within

the focus of modern application. In this work, we demonstrated the application of electron

irradiation as a powerful tool for tailoring these properties. In particular we demonstrated the

efficient surface modification of NDs based on a pulse radiolysis approach of ND suspension.

As a test model we established the efficient surface chlorination of NDs by electron irradiation

of ND suspension in halogenated solvents.1 Furthermore, electron irradiation was applied for

the effective formation of lattice vacancies, in order to enhance the formation of NV centers.

Within a comprehensive study we demonstrated that the formation and the resulting properties

of NV centers can be controlled via irradiation treatments, parameters and the surface

functionalities.2

Reference(s)

1. J. Zhou, C. Laube, W. Knolle, S. Naumov, A. Prager, F.-D. Kopinke and B. Abel, Diamond and Related Materials, 2018, 82, 150-159.

2. C. Laube, T. Oeckinghaus, J. Lehnert, J. Griebel, W. Knolle, A. Denisenko, A. Kahnt, J.

Meijer, J. Wrachtrup and B. Abel, Nanoscale, 2019, 11, 1770-1783.

Figure 3 Shematic illustration of the preparation approaches

for the nanodiamond surface chlorination (above)

and NV center formation (below).



21

P6: Hydrogen Production by Steel Anoxic Corrosion under Gamma

Irradiation

Lina Giannakandropoulou1, Benoît Marcillaud1, Stéphane Poirier1, Hortense Desjonqueres1,

Charles Wittebroodt2, Gérard Baldacchino3

1Institute for Radiological Protection and Nuclear Safety (IRSN), PSN-RES/SCA/LECEV, BP68, Gif-sur-Yvette, France;

2Institute for Radiological Protection and Nuclear Safety (IRSN), PSE-ENV/SEDRE/LETIS, BP17,

Fontenay-aux-Roses; 3LIDYL, Université Paris-Saclay, Atomic Energy and Alternative Energy Commission (CEA), Gif-sur-

Yvette, France.

In the framework of the storage of High Level nuclear Wastes (HLW), ANDRA (National

Radioactive Waste Management Agency in France) is planning their isolation in deep

geological disposals. Such a disposal repository concept is based on a multi-barrier system

including large amount of metallic elements such as stainless steel primary canister or carbon

steel casing for HLW disposal gallery. After a period of several decades, anoxic corrosion of

these metal elements will cause a release of hydrogen gas [1]. Simultaneously, the radiation

emitted by radioactive wastes would lead to the radiolysis of the water present in the

geological formation. This process may lead to a production of additional hydrogen gas and

other redox species likely to modify the redox conditions of the aqueous medium as well as the

corrosion processes of the steel and therefore, the hydrogen production [2].

This study aims at assessing the influence of

-irradiation on H2-production rate through the

anoxic corrosion of carbon steel process. Two

experimental stainless steel cells are placed in an

irradiation chamber IRMA (IRSN facility)

where they are exposed to -radiation of 60Co

(50 Gy/h) for twelve days. The first cell contains

carbon steel coupons (15 gr) immerged in pure

deaerated water (100 mL) and the second cell

contains only pure deaerated water. An He-gas

flows through these cells to a gas chromatograph

for measuring the evolution of H2-production

before, during and after irradiation. Post-mortem analysis are then performed on liquid and

solid phases. Metallic samples is structurally characterized for the identification of the formed

corrosion products upon their surfaces with XRD, μRaman spectroscopy and SEM-EDS

microscopy. The loss of mass of the coupons is measured in order to estimate the carbon steel

corrosion rate. Liquid samples are analysed for their Eh and pH values. In parallel, UV-Vis

spectroscopy is used to determine the concentration of both dissolved Fe2+ and Fe3+ ions. A

fluorescence method is used to assess the hydrogen peroxide (H2O2) concentration. Finally,

kinetics are compared with those obtained by simulations using Chemsimul software. First

results on H2-production show that our experiment allows us to distinguish in time the

contributions of the solid phase (corrosion) and the radiolytic processes in the bulk of the liquid

phase. These results are also supported by simulation in the homogeneous liquid phase but

needs an heterogeneous approach modelling the interface processes.

References

1. Smart, N.R., Rance, A.P., Werme, L.O., 2008.The effect of radiation on the anaerobic corrosion of steel. Journal of Nuclear Materials 379, 97-104.

2. Pimblott, S. M. and LaVerne J. A., 1992. Molecular product formation in the electron radiolysis of

water. Radiation Research 129(3): 265-271.

Figure 1 : µRaman spectra indicates the

presence of magnetite at 675 nm.



22

I7: On Radiolytic Hydrogen Production in Oxide and Hydroxide Sludges

M. O’Leary1, I. P. Dolbnya2, A. Baidak1, C. Emerson3, C. Figueira3, O.J.L. Fox2, A.K.

Kleppe2, A. McCulloch3, D. Messer1, and F. Currell1

1Dalton Cumbrian Facility (The University of Manchester), Cumbria, UK; 2Diamond Light Source, Oxfordshire, UK; 3Queen’s University Belfast, Antrim, UK.

The radiolytic hydrogen yield and hydrogen diffusivity was measured in a number of oxides

(ZrO2, TiO2, ZnO, Al2O3, CeO2) and hydroxides (Mg(OH)2 ). These yields where determined

with a previously presented method [1] involving electrochemical hydrogen probes from

Unisense A/S [2]. The hydrogen concentration was measured with a probe a millimetre above

the irradiated region in the sludge. The lower limit to these diffusivities is described by a simple

model, blue curve on graph in figure 1. These results indicate that the hydrogen is not holding

up on the surface of the nano-particles of these oxides. The radiolytic yield of hydrogen in all

sludges are significantly increased over the expected yield for water alone, which would be 0.5

µmol/J.

Some of these sludges where irradiated with the full x-ray spectrum of the synchrotron, called

white beam irradiation. These sludges where imaged during these irradiations. These images

show the formation of micro bubbles in these sludges, as seen in figure 2. These bubble

formation dynamics further illuminate the behaviour of hydrogen in these sludges.

Reference(s)

1. O’Leary, M. et al. (2017) Method for the determination of Effective Diffusivity and G-value of

Hydrogen in Magnox Sludge Mimics. 30th Miller Conf.

2. Online: https://www.unisense.com/H2/ (retrieved 20/6/19)

3. Zhou, Tunhe, et al. (2018) Development of an X-ray imaging system to prevent scintillator

degradation for white synchrotron radiation. Journal of synchrotron radiation.

Figure 1 The relationship between

nanoparticle concentration and hydrogen

diffusivity in sludges.

Figure 2 Three x-ray images taken with a

PCO edge camera [3] of a magnesium

hydroxide sludge undergoing irradiation by

white beam at the Diamond Light Source.

The first at the irradiation start. The second

image taken at 20 seconds into irradiation,

shows earliest signs of bubble formation.

Third image shows a definite spherical

bubble which appears 27 seconds into

irradiation. The red circle surrounds the

bubble in the third image and the same

region in the other images.



23

I8: Radiation-Induced Chemistry on Polymer-Liquid Interfaces and

Diffusive Behaviour of H2

Aliaksandr Baidak,1,2 Imene Boughhattas,1,2 Gemma Draper, 1,2 Darryl Messer, 1,2 Mel

O’Leary 1,2

1 Department of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom

2 Dalton Cumbrian Facility, University of Manchester, Westlakes Science Park, Moor Row, Cumbria,

CA24 3HA, United Kingdom

Radioactive sludges made of organic materials and water are commonly encountered in nuclear

industry. Radiolytic processes in such systems often pose a serious safety hazard during the

long-term storage of these materials due to the release of flammable gases or production of

corrosive water-soluble products. In particular, polystyrene-based (PS) ion exchange resins

(IERs) are commonly used for radioisotope separation process, nuclear waste treatment and

reactor coolant demineralisation. [1] After their use, IERs with accumulated radionuclides

become hazardous materials; at this point they are handled as low or intermediate level nuclear

waste. [2] In the context of the long-term storage of nuclear waste it is important to discriminate

the effects of the high vs. low Linear Energy Transfer (LET) radiation on the IERs since both

alpha and gamma emitting radioisotopes might be present in spent ion exchange resins.We

report the radiation chemical yields for the degradation of several IERs materials obtained

through 20 keV synchrotron X-ray, Co-60 gamma and 5.5 MeV He2+ ion irradiations.

We have determined the absolute yields (G-values) as well as diffusion behaviour of H2 from

several nuclear grade ion exchange resins. For the IER-containing slurries we also measured

the yields of pH active leachates (H2SO4 or (H3C)3N) to evaluate their effect on the H2

formation.

Obtained results reveal that the radiation hardness of the studied resins largely depends on the

type of a functional group they possess. The polystyrene and the sulphonated cation exchange

resin produce relatively low yields of H2, whereas the mixed bed and especially the anion

exchange resin form appreciable amounts of molecular hydrogen. [4] All studied polymers

show an increase in molecular hydrogen yield with increasing LET as it follows from

comparison of the helium ion vs. gamma radiolysis. Such increase in net molecular hydrogen

yield at a higher LET might be explained by the second-order reactions competing efficiently

with self-scavenging reactions of H atoms by the aromatic moieties of PS. Furthermore, our

experiments show that the G(H2) is strongly dependent upon the relative amount of water

associated with the resin. Using X-ray tomography, we have successfully visualised the in situ

H2 bubble formation in resin-water slurries. The initial shape of bubbles, and their subsequent

growth and escape is found to be dependent on an average particle size of the resin. This finding

might be important while considering the diffusion of H2 in a resin-water slurry; it provides

further valuable insight into the hydrogen transport in organic nuclear waste.

In summary, the comprehensive radiation chemistry study of IERs presented here provides

helpful guidelines for a safe management of the organic nuclear waste.

References:

1. J.J. Wolff. Purolite Ion Exchange Resins, Bala Cynwyd, USA, (2012).

2. K.K.S Pillay. J. Radioanal. Nucl. Chem., 97, 135 (1986)

3. C. Rebufa et al. Rad. Phys. Chem., 106, 223 (2015)

4. A. Baidak, J. A. Laverne. J. Nucl. Mat., 407, 211 (2010).



24

P7: Radiolytic Degradation of an Extractant for Actinides, HONTA — a

Comparative Study of Direct and Indirect Radiolysis Processes

Y. Kumagai1, T. Toigawa1, S. Yamashita2, T. Matsumura1

1Japan Atomic Energy Agency, Ibaraki, Japan; 2The University of Tokyo, Ibaraki Japan.

Ionizing radiation induces degradation of organic molecules. This action of ionizing radiation

needs to be incorporated in designing and safety evaluation of solvent extraction processes for

separation of radioactive elements [1]. A reliable estimation of the effect of radiolysis requires

understanding of the degradation mechanism as well as basic data regarding the extractant

degradation and its radiolytic products. This study focuses on a promising extractant for

separation of actinides from lanthanides, hexaoctyl- nitrilotriacetamide (HONTA) [2]. We have

investigated the radiolysis of HONTA by LC-MS/MS analysis of radiolytic products of

HONTA and by UV-visible spectroscopy of its radical transient using pulse radiolysis

technique. In these experiments, radiolysis of neat HONTA and that of HONTA in dodecane

solvent are compared in order to understand the degradation mechanism.

The samples for the product analysis were irradiated by 60Co γ-ray (60Co irradiation facility,

QST Takasaki) and were analysed by an LC-MS/MS system (Shimadzu, LCMS-8300). The

mass-chromatograms for the irradiated neat HONTA and 10 mM HONTA in dodecane are

shown in Figure 1. We found 43 products, in total, of HONTA degradation. Among them, 14

products were commonly observed in the radiolysis of neat

HONTA and the dodecane solution, 20 products were only

found in the neat HONTA, and 9 products are characteristic

for the dodecane solution. Indeed, 14 out of 43 products are

common in these two, although the initial radiolysis

processes in these samples must be different, i.e. direct

ionization and excitation of HONTA occur under neat

condition, whereas the degradation of HONTA is due to

reactions of radicals from dodecane radiolysis in the

solution. This result suggests that the direct and the indirect

processes have a common reaction pathway. Therefore, we

measured absorption spectra of transient species by using a

nano-second pulse radiolysis system. (LINAC facility,

Univ. Tokyo) in order to investigate the reaction pathways.

The measured spectra had similar shapes in this time

domain regardless of the HONTA concentrations. This

indicates that there is a common transient both in the

radiolysis of neat HONTA and of dodecane solution of

HONTA. Consistently with the product analysis, the result

of the pulse radiolysis experiment indicates a common

reaction pathway between the direct and the indirect

radiolysis. Acknowledgment: This work was supported by JSPS KAKENHI Grant Numbers JP18K05001.

References

1. Mincher, B.J., Modolo, G., and Mezyk, S.P. (2009) Review Article: The effects of radiation

chemistry on solvent extraction 3: A review of actinide and lanthanide extraction. Solvent Extr. Ion

Exch., 27, 579-606

2. Sasaki, Y., Tsubata, Y., Kitatsuji, Y., and Morita, Y. (2013) Novel Soft-Hard Donor Ligand,

NTAamid, for Mutual Separation of Trivalent Actinoids and Lnthanoids, Chem. Lett., 42, 91-92.

Figure 1 Mass chromatograms of the irradiated samples (130 kGy); (a) neat HONTA, (b) 10mM HONTA in n-dodecane.



25

H1: Research in Radiation Chemistry to Support the Safe Storage of

Plutonium on the Sellafield Site

H. Steele and J. Hobbs

Sellafield Ltd. Seascale Cumbria CA20 1PG UK.

The UKs plutonium inventory has been safely stored on the Sellafield site for over 40 years.

The majority of the plutonium is stored in its oxide form, in gas-tight packages that were sealed

following heat treatment and conditioning. However, the radioactive decay of plutonium results

in the generation of heat, alpha particles and gamma radiation which can perturb conditions

within the packages. In order to ensure onward safe storage, including the necessity for

transportation, and package inspection it is essential to understand how the emitted radiation

interacts with residual adsorbed materials, packaging and the range of internal head-gases.

Radiation plays a dual role within PuO2 containing packages, that of the foe in decomposing

contaminants and materials and a friend in catalysing recombination reactions. To understand

the totality, Sellafield Ltd has undertaken a number of research activities of what is a complex

field and experimentally very challenging.

Figure 4 Recombination of H2 and O2 due to adsorbed dose. L Jones DCF



26

H2: The Radiation Chemistry of Spent Nuclear Fuel Systems

W S Walters

National Nuclear Laboratory, Building D5, Culham Science Centre, Abingdon, Oxfordshire, UK;

Radiation chemistry is a major factor in the “features, events and processes” which describe

the technology attending the safe management of spent nuclear fuel. The radiation chemistry

involves interactions between the ionising radiation emitted from the fuel and absorbing

medium (be that water in a pond, or a gas in a dry store arrangement).

The radiolysis of water has been well studied down the years. The principal products are

molecular hydrogen, hydrogen peroxide, and oxygen, along with steady state concentrations of

various radicals and ionic species. The mechanism, yields and reaction kinetics of the radiolytic

reactions are well known 1. However, the possibility of hydrogen and oxygen accumulating in

any gas space present serves to raise safety concerns for nuclear plant; an understanding of

rates of gas production and yields are of key importance in underpinning any safety case.

Computer modelling of such radiolytic systems has long been used to predict the development

of gas mixtures in operational plant. However the effects of solutes or pH adjustments to the

pond water may have the effect of altering gas production rates from those associated with pure

water. This presentation will include consideration of the basics, the modelling approaches,

with chemistry effects and their impact in real plant situations.

The radiation chemistry is also influenced by interactions with surfaces. Some of the energetic,

short lived radical species which reach steady state in an irradiated aqueous solution (together

with oxygen and hydrogen peroxide) may be capable of oxidising metal surfaces in ways that

water would normally not. Because spent nuclear fuel systems usually contain a number of

different metals (the container, the fuel cladding, any dissimilar metal components which are

part of the container, the fuel, or pond facility, have the possibility of removing oxidising

species from the radiolytic system and producing a metal oxide (or hydroxide) along with a

nett reducing radiolytic environment, which in turn influences further radiolysis 2. These effects

will be described.

Dry storage of nuclear fuel has many equivalent features – i.e. radiolysis of the principal cover

gas (but also including any minor impurities in the gas). Depending on the availability of such

impurities, some molecular products are possible which represent acidic or alkaline species and

these in turn are capable of interacting with metallic materials in the fuel containment system.

The transfer of energy from “inert” gases to impurity products also affects the rate of

production of chemically active species. Examples will be presented of how gaseous systems

may interact with stored fuel, particularly in a UK context.

Reference(s)

1. Elliot, A.J. and Bartells, D.M. (2009) “The Reaction Set, Rate Constants and g-Values for the

Simulation of the Radiolysis of Light Water over the Range 20° to 350°C Based on Information

Available in 2008” AECL report 153-1 271 60-450-001.

2. LeCaer, S. Water Radiolysis: “Influence of Oxide Surfaces on H2 Production under Ionizing

Radiation”. Water 2011, 3, p 235-253.



27

THURSDAY 12th SEPTEMBER

08:00 Sunrise Session - Health, Fred Currell and Joao Alberto Osso Junior

09:00

09:35

10:10

10:35

Health–I Session, Chair - Joao Alberto Osso Junior

I9: “Monte Carlo Track-Structure Simulations for Boron-Neutron Capture

Therapy” Jose Ramos-Mendez

I10: “Nanoagents to Improve Radiotherapy and Hadrontherapy Performances:

Green Synthesis and Impact on Blood Proteins” Sandrine Lacombe

P8: “Study on the Dose Enhancement in Water by Activation of Clusters of

Nanoparticles of High-Z Materials with a 6 MeV True Varian Linac” Balder

Villagomez-Bernabe

P9: “New Explanation for Radiosensitization by Gold Nanoparticles: Chemical

Effect” Viacheslav Scherbakov

11:00 Coffee

11:30

12:05

12:30

Health–II Session – Chair - Chantal Houée-Levin

I11: “Oxygen Effects on Antioxidant Protection of Lymphoid Cells against Free

Radicals by a Range of Dietary Carotenoids” Ruth Edge

P10: “Effects of Additives on Radiation-Induced DNA Damage: From the

Viewpoints of Free Radical Scavenging and Chemical Repair” Hao Yu

P11: “Solvation Effects on Dissociative Electron Attachment to Thymine” Bin Gu

12:55 Coaches to DCF

13:30 Lunch and Tours of DCF (Trustees Business Meeting using DCF meeting room)

16:30 Coach to Cockermouth (free time until 18:30 then coach to Energus)

19:00 Conference Dinner, return coaches at 23:00



28

I9: Monte Carlo Track-Structure Simulations for Boron-Neutron Capture

Therapy

J. Ramos-Méndez1, N. Domínguez-Kondo2, E. Moreno-Barbosa2 and B. Faddegon1

1Department of Radiation Oncology, University of California San Francisco, California, USA; 2Facultad de Ciencias Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, Puebla,

MEX.

Boron neutron-capture therapy (BNCT) promises much reduced damage to healthy

tissue, with the dose distribution conforming precisely to the target when boron is preferentially

delivered to the tumour. After a thermal neutron is captured by boron, two ion recoils with very

short range (<10 μm) are released: a 0.84 MeV lithium-ion and a 1.47 MeV alpha particle.

Characterization of the track-structure of these combined ions is important to the understanding

of radiobiological effectiveness of BNCT. The open source Geant4-DNA Monte Carlo track

structure code is a good candidate to perform this task, due to its flexibility and accuracy.

However, Geant4-DNA physical cross-sections for ions heavier than alphas are unavailable

below 1 MeV/u. The aim of this work was to extend the inelastic cross-sections for lithium

ions of Geant4-DNA to low enough energies to characterize the track-structure of BNCT and

the subsequent radiolysis process.

The Barkas’ effective charge factor [1] was used to

extend, down to 100 eV/u, the inelastic cross sections of ions

from those of protons and hydrogen ions available in

Geant4-DNA. A phenomenological two-factor correction to

account for the differences in the cross-sections observed in

carbon-ion data from the literatue was applied. To verify the

calculated cross-sections, the stopping power of carbon and

lithium ions in water was calculated and compared with data

from ICRU [2] and Montenegro et al [3]. In addition, G-

values (species per 100 eV of energy deposited) from an

alpha-lithium source interacting in neutral water were

calculated with the Independent Reaction Times method.

Satisfactory agreement was found between

calculated ion stopping power and published data for low

energies (1 keV/u - 1 MeV/u) with an overall convergence

at higher energies (Figure 1). Calculated G values from

alpha-lithium source will be presented.

A set of lithium cross-sections suitable for BNCT

track-structure studies have been made available in Geant4-

DNA.

Reference(s)

1. Schmitt, E., Friedland, W., Kundrát, P., Dingfelder, M. and Ottolenghi A. (2015) Cross-section

scaling for track structure simulations of low-energy ions in liquid water Radiat. Prot. Dosimetry 166

15–8.

2. International Commission on Radiation Units and Measurements. (2005) Stopping of ions heavier

than helium. ICRU Report 73.

3. Montenegro, E.C., Shah, M.B., Luna, H., Scully, S.W.J., de Barros, A. L.F., Wyer, J.A. and

Lecointre, J. (2007) Water fragmentation and energy loss by carbon ions at the distal region of the

Bragg peak. Phys. Rev. Lett. 99, 21320.

Figure 1. In-water stopping

power for carbon (black) and

lithium (blue) ions. Data

from the literature is shown

with markers.

0

100

200

300

400

500

600

700

800

900

1000

100

101

102

103

Carbon-ion

Lithium-ion

Sto

ppin

g p

ow

er

(keV

/mm

)

Energy (keV/u)

Geant4-DNA

ICRU

Montenegro



29

I10: Nanoagents to Improve Radiotherapy and Hadrontherapy

Performances: Green Synthesis and Impact on Blood Proteins

S. Lacombe

ISMO UMR, Université Paris Saclay, Université Paris Sud, CNRS, Orsay cedex, France

Radiotherapy and chemotherapy are the gold standards to treat cancer. Recently, it was

shown that metal-based nanoparticles could improve the performance of radiotherapy. 1

Currently, the production of radio-enhancing nanodevices (e.g. gold nanoparticles, hafnium

dioxide nanodevices etc..) is processed via chemical synthesis, which often involves the

utilization of toxic solvents. Hence, multiple steps of cleaning are used to obtain

biocompatible and sterile solutions, which degrades the production and increases

environmental hazard. The group optimized a new solvent-free, “green” and highly

reproducible method to produce small, non-toxic and stable radio-enhancers diluted in sterile

solutions, with 100% rate.

In parallel, a synchrotron radiation circular dichroism experiment has been optimized to

characterize their impact (toxicity) on blood proteins.

In summary, the development of alternative approaches to design and test novel radio-

enhancers is a new era, which should lead to a dramatic improvement of cancer treatments.

Reference 1 Kuncic, Z.; Lacombe, S. Nanoparticle radio-enhancement: Principles, progress and application to

cancer treatment. Phys. Med. Biol. 2018, 63, 02TR01.



30

P8: Study on the Dose Enhancement in Water by Activation of Clusters of

Nanoparticles of High-Z Materials with a 6 MeV True Varian Linac

B. Villagomez-Bernabe1,2 and F. Currell1,2

1Chemistry Department, The University of Manchester, Manchester, UK; 2Dalton Cumbrian Facility, Cumbria, UK.

During the last decade, different nanomaterials have been implemented for biomedical

applications in Nanomedicine, such as imaging agents [1] and drug delivery agents [2].

Furthermore, different types of nanoparticles are being studied as radiosensitizers in cancer

treatment [3,4]. This work aims to calculate through Monte Carlo simulations the dose

enhancement in water for three different nanoparticles composition such as gold, silver and

gadolinium in order to compare their effectiveness based only on the physical interactions

between gamma irradiation and the nanoparticles, i.e. without taking into account the influence

of the radicals formed by each type of nanoparticles. Nevertheless, as far as the authors are

aware, such a computational study involving clustering of nanoparticles has not been published

to date.

The present work is divided into two stages, during the first

stage, the random positions of the nanoparticles inside a

water sphere were calculated using Wolfram Mathematica.

This mimics the sub-cellular distribution of nanoparticles

commonly observed using microscopy. Those coordinates

were used to create a parameter file in TOPAS [5] with the

information of the position, material and size of the

nanoparticles. The geometry set-up created with the

parameter file is shown in Fig. 1, where a cluster of

nanoparticles was loaded into TOPAS for posterior

irradiation with a 6 MeV True Varian Linac obtained from

the International Atomic Energy Agency website. Then, a

phase space file placed around the cluster of the

nanoparticles was used to record all electrons going out from the cluster. The final stage

involves the releasing of all particles from the space phase file previously recorded during stage

1 into a water phantom in order to measure the dose deposited in radial bins around the cluster.

The Geant4-DNA physics list was used to track low energy electrons down to 10 eV. The radial

dose distribution for each type of nanoparticle were compared against each other and plotted

for better visualization.

Reference(s)

1. Rippel R.A. and Seifalian A.M. (2011) Gold Revolution -Gold nanoparticles for modern medicine

and surgery. Journal of Nanoscience Nanotechnology, 11, 7340-48.

2. Ghosh P., Hang G., De M., Chae K.K. and Rotello V.M. (2008) Gold nanoparticles in delivery

applications. Advanced Drugs Delivery Reviews, 60, 1307-15.

3. McMahon S.J. et al (2011) Nanodosimetric effects of gold nanoparticles in megavoltage radiation

therapy. Radiotherapy Oncology, 100, 412-416.

4. Taupin F. et al. (2015) Gadolinium nanoparticles and contrast agents as radiation sensitizers.

Physics in Medicine and Biology, 60, 4449-64.

5. Perl, J. et al. (2012) TOPAS: an innovative proton Monte Carlo platform for research and clinical

applications. Med Phys., 39, 6818-37.

Fig. 1. cluster of

nanoparticles randomly

distributed.



31

P9: New Explanation for Radiosensitization by Gold Nanoparticles:

Chemical Effect

V. Shcherbakov, N. Chen, S.A. Denisov and M. Mostafavi

Laboratory of chemical physics/CNRS_Université Paris-Saclay, Orsay, France

Gold nanoparticles (AuNPs) are presented to be an efficient radiosensitizer for cancer

radiotherapy [1]. During the last decades, many important works were performed to show the

radiosensitization by different particles for different tumors. But still, there is no explanation

for AuNPs radiosensitizating effect. Physical explanation based on Compton, photoelectric and

Auger effects cannot explain the radiosensitizing effect in solutions, because the nanomolar

concentration of AuNPs does not change dose deposition in the solution. Therefore, other ideas

were proposed such as overproduction of ∙OH radicals [2] due to special properties of

interfacial water around nanoparticles and

scavenging of excess electrons [3, 4] what

increases the concentration of ∙OH radicals

around the nanoparticles.

In the present work, we show by pulse radiolysis

that AuNPs react neither with reducing radicals:

pre-solvated electron, solvated electron (e-s), ∙H

nor oxidizing one ∙OH, what is manifested in the

same e-s formation yields (5 ps) in the presence

and absence of AuNPs; and the same decay of e-

s in microsecond time range [5]. In addition,

unchanged e-s decay in the presence of AuNPs

showed that overproduction of OH radicals is not

occurring. In the present work we perform a new

approach to show the effect of AuNPs in

radiosensitization.

As biological systems are complex, therefore here we used simple organic models to conclude

on the mechanism of the radiosensitizing effect of AuNPs. By gamma radiolysis, we show that

in an irradiated solution of 2-propanol in the presence of AuNPs the radiolytic yield of acetone

– the product of oxidation of alcohol, is higher than in the absence of nanoparticles (Figure 1).

Such studies were carried out for other organic compounds in order to confirm the effect of

gold nanoparticles on this radiolytic enhancement. In our work we will propose the detailed

mechanism and discuss how it can explain radiosentisization by AuNPs.

References:

1. Wang, H., Mu, X., He, H., & Zhang, X. D. (2018). Cancer radiosensitizers. Trends in pharmacological sciences, 39(1), 24-48.

2. Gilles, M., Brun, E., & Sicard-Roselli, C. (2018). Quantification of hydroxyl radicals and solvated

electrons produced by irradiated gold nanoparticles suggests a crucial role of interfacial water.

Journal of colloid and interface science, 525, 31-38.

3. Ghandi, K., Wang, F., Landry, C., & Mostafavi, M. (2018). Naked Gold Nanoparticles and hot

Electrons in Water. Scientific reports, 8(1), 7258.

4. Ghandi, K., Findlater, A. D., Mahimwalla, Z., MacNeil, C. S., Awoonor-Williams, E., Zahariev, F.,

& Gordon, M. S. (2015). Ultra-fast electron capture by electrosterically-stabilized gold nanoparticles.

Nanoscale, 7(27), 11545-11551.

5. Shcherbakov, V., Denisov, S.A., Ghandi, K., Mostafavi, M., Pulse radiolysis study of AuNPs

solutions. (to be published)

Figure 1. The dose dependent of acetone

formation in 2-propanol solution in the

presence and absence of AuNPs.



32

I11: Oxygen Effects on Antioxidant Protection of Lymphoid Cells against

Free Radicals by a Range of Dietary Carotenoids

R. Edge1, F. Boehm2 and T.G. Truscott3

1Dalton Cumbrian Facility, The University of Manchester, Westlakes Science Park, Moor Row, Cumbria, UK;

2Photobiology Research, IHZ, Berlin, Germany; 3School of Physical Science (Chemistry), Keele University, Staffordshire, UK.

Carotenoids are natural pigments, being constituents of a wide variety of fruits and vegetables,

though chlorophyll often masks their presence. Believed to act as dietary antioxidants, having

been shown to quench both singlet oxygen and a range of free radicals, carotenoids are of

interest for their health benefits. While carotenoids are consumed in significant quantities from

normal diets, in recent years, they are also consumed in large quantities via food supplements.

This may well be based on claims that they offer major health benefits but there are also

counter-claims that they can be damaging to human health.

We have shown previously that dietary lycopene, the red carotenoid pigment in tomatoes,

protects against human lymphoid cell membrane damage from free radicals produced by γ-

radiation and that this protection is dramatically reduced when the oxygen concentration is

increased [1].

In this work we study a wider range of dietary carotenoids, showing protection of human

lymphoid cells from membrane damage caused by free radicals produced by γ-radiation. Blood

was taken from volunteers who had supplemented their diet with large doses of a specific

carotenoid for 2 weeks or had minimized carotenoid-rich fruit and vegetables in their diet.

Radical-induced cell membrane destruction was shown by cell staining with eosin.

All carotenoids studied imparted protective effects and the carotenoid protective effect was

reduced as oxygen concentration increased, as previously seen for lycopene. In fact, the oxygen

effect was observed to be most pronounced for lycopene, where there was almost no protection

under 100% oxygen, down from 5-fold protection at 21% oxygen and, an extremely high, 50-

fold, protection in the absence of oxygen. Studies with β-carotene and the xanthophylls,

astaxanthin, zeaxanthin and lutein, have shown a reduced, but still significant, oxygen effect.

Gamma radiation cellular studies have also been undertaken with the addition of superoxide

dismutase, showing that the effect is not due to reactions of the superoxide radical.

Additionally, a series of non-cellular gamma radiolysis studies in simple solutions, as well as

cell protection studies against nitrogen dioxide radical, generated photolytically, have also been

carried out to help elucidate the molecular mechanisms for the observed oxygen effect.

The remarkable reduction in protection by carotenoids, particularly lycopene, against gamma

radiation at high oxygen concentrations could, perhaps, be exploited to enhance radiation

procedures for therapy.

References

1. Boehm, F., Edge, R., Truscott, T.G. and Witt, C. (2016) A dramatic effect of oxygen on protection

of human cells against γ-radiation by lycopene. FEBS Lett., 590, 1086-1093.



33

P10: Effects of Additives on Radiation-Induced DNA Damage: From the

Viewpoints of Free Radical Scavenging and Chemical Repair

H. Yu1, K. Fujii2, A. Yokoya2 and S. Yamashita1

1The University of Tokyo, Tokyo, JAPAN; 2Natinal Institutes for Quantum and Radiological Science and Technology (QST), Chiba, JAPAN.

1. INTRODUCTION

Radiation-induced DNA damage can be reduced by small amount of additives like

antioxidants. Such additives can repair unstable oxidative damage intermediately produced in

DNA by reductive reaction (chemical repair) as well as remove oxidizing radicals such as •OH

produced as a result of water radiolysis (radical scavenging). Low concentration of additives

cannot remove all of the oxidizing radicals, therefore, the chemical repair process must be more

important. We investigated the effect of additives against radiation damage to DNA. For this

purpose, pulse radiolysis experiments were conducted to observe the additive’s reactions not

only with radicals produced by water radiolysis but also with a tentatively oxidized DNA model

compound. In this study, dGMP (deoxyguanosine monophosphate, purchased from Thermo

Fisher Scientific) was used as model compound of DNA moiety. In addition, a gel

electrophoresis was conducted to evaluate the yield of stable DNA damage.

2. EXPERIMENT

Pulse radiolysis was conducted at the LINAC facility of the University of Tokyo. Details of

the apparatus are described in elsewhere[1].

Plasmid DNA, pUC18, was extracted from cultured Escherichia coli (JM109) and purified

by dialysis to remove organic impurities. Dilute aqueous solutions and films of the plasmid

DNA were irradiated with X-rays and stable DNA damage were detected and quantified by an

agarose gel electrophoresis method[2].

As additives, we used Tris-EDTA (TE), which are the solutes of pH buffer often used for

DNA storage, and typical antioxidants such as ascorbic acid (purchased from Fujifilm Wako)

and flavonoid rutin (received from Toyo Sugar or purchased from Fujifilm Wako).

3. RESULTS & DISCUSSION

Transient absorption spectra of the scavenging reaction of rutin toward •OH had at least three

peaks, which were attributed to the products of OH adduct, hydrogen atom subtraction, and

electron subtraction. The ratio of the peak intensities was not constant, indicating an

intramolecular transformaton following the scavenging reaction. On the other hand, the reacion

of rutin toward tentatively oxidized dGMP radical showed a clear peak in the spectra, which

was the same as the peak corresponding to hydrogen abstraction observed for the scavenging

reaction as described above.

Purification by dialysis resulted in higher yields of stable DNA damage induction, indicating

that non-negligible impurities could protect the DNA from radiation damage. The damage

yields in dilute aqueous solutions were much higher than those in hydrated plasmid DNA films.

This suggests that additional damage is produced due to the indireact actions of radicals

produced by watar radiolysis.

References

[1] K. Hata, et al., J. Radiat. Res., 52, 15 (2011).

[2] A. Yokoya et. Al., J. Am. Chem. Soc. 124, 8859 (2002).



34

P11: Solvation Effects on Dissociative Electron Attachment to Thymine

Jorge Kohanoff 1 and Bin Gu1,2

1Atomistic Simulation Centre, Queen’s University Belfast, Belfast BT7 1NN, U.K.; 2Department of Physics, Nanjing University of Information Science and Technology, Nanjing 210044,

China.

Ionizing radiation can excite the cellular medium to produce secondary electrons that can

subsequently cause damage to DNA. The damage is believed to occur via dissociative electron

attachment (DEA). In DEA, the electron is captured by a molecule in a resonant antibonding

state and a transient negative ion is formed. If this ion survives against electron

autodetachment, then bonds within the molecule may dissociate as energy is transferred from

the electronic degrees of freedom into vibrational modes of the molecule.

We present a model for studying the effect that transferring kinetic energy into the vibrational

modes of a molecule has on a DNA nucleobase. To simulate the effect of the additional energy

that would be introduced due to a DEA event, we vertically attached an excess electron to the

system and introduced additional vibrational energy to the N−H bond. We can tune the

vibrational energy of a molecular bond by increasing the velocities and hence the kinetic

energies of the constituent atoms.

We found that the breaking of an N−H bond and releasing a hydrogen atom, which in the gas

phase requires 1.67 eV, is strongly affected by the aqueous environment. When there is a

hydrogen bond between the N−H of the nucleobase and a surrounding water molecule, there is

no guarantee that the bond breaks even when up to 5 eV of additional energy is inserted into

the bond. The reason for this is that this hydrogen bond rapidly channels the kinetic energy

away from the N−H, into the surrounding water molecules, and back into the nucleobase.

Fig. 1 The reaction channels of the (Transient negative ion) TNI of thymine with low energy

dissociative electron attachment (DEA) in aqueous solvent, with the relevant potential energy surface

(PES) shown as functions of the N-H distance.

Reference

McAllister, M., Kazemigazestane, N., Henry, L. T., Gu, B., Fabrikant, I., Tribello, G. A., & Kohanoff,

J. (2019). Solvation Effects on Dissociative Electron Attachment to Thymine. The Journal of Physical

Chemistry B, 123(7), 1537–1544.



35

FRIDAY 13th SEPTEMBER

08:00 Sunrise Session - Energy, Chaired by Robin Orr and Dan Whittaker

09:00

09:35

10:10

10:35

Energy–I Session, Chair - Robin Orr

I12: “Rapid Capture of Holes in Organic Solvents Studied by Picosecond Pulse-

Radiolysis” Andrew Cook

I13: “Radiation Energy Transfer Simulation toward Extraction Solvent in Minor

Actinide Separation Process” Tomohiro Toigawa

P12: “Effect of Supports on Metal-Nanoparticle Catalysts: The Radiolytic H2

Evolution Reaction” Tomer Zidki

P13: “Radiation-Induced Redox Chemistry of Californium-249” David Meeker

11:00 Coffee

11:30

12:05

12:40

Energy–II Session, Chair - Dan Whittaker

I14: “Capturing Sunlight with Molecular Systems – A Pulse Radiolysis

Investigation into Charge Recombination and Escape for Solar Energy

Conversion” Matthew Bird

I15: “Drastic Changes in the Surface Reactivity of UO2-Based Spent Nuclear Fuel

upon Exposure to Radiolytic Oxidants – How Will This Influence the Safety

Assessment of Deep Geological Repositories for Spent Nuclear Fuel?” Mats

Jonsson

P14: “Reduction of Cobaoxime-Based Complexes: Mechanisms, Products and

Implications” Axel Kahnt

13:05 Lunch

14:00 Educational Session – Materials, Laura Leay and Clelia Dispenza

15:00

15:35

16:10

16:35

Materials-I Session – Chair, Clelia Dispenza

I16: “Heterogeneous Alteration of a Mimas MOX Fuel under Oxidizing

Conditions Revealed by Raman Spectroscopy” Lola Sarrasin

I17: “Heavy Ion-Induced Defect Production in Single-, Few-Layer and Bulk

Crystals of MoS2” Liam Isherwood

P15: “γ-Radiolysis of Thermal Transition Phases in Boehmite” Patricia Huestis

P16: “Key Role of the Oxidized Citrate Free Radical in the Nucleation

Mechanism of the Metal Nanoparticles Turkevich Synthesis” Sarah Al Gharib

17:00 Coffee

17:30

18:05

18:30

Materials-II Session, Chair Laura Leay

I18: “The Effects of Gamma Radiation on the Accelerated Carbonation of Fly-

Ash Blended Cement” Alex Potts

P17: “The Radiation Chemistry of Aqueous PVP Solutions Exposed to Pulsed E-

beam Irradiation: Experiments and Numerical Simulations” Clelia Dispenza

P18: “Internal Structure and Composition of Fukushima-Derived Particulate

Revealed through Combined Synchrotron and Mass-Spectrometry Techniques”

Peter Martin

18:55 Conference Closing Remarks

19:00 Coaches to Cockermouth



36

I12: Rapid Capture of Holes in Organic Solvents Studied by Picosecond

Pulse-Radiolysis

Andrew R. Cook and John R. Miller

Brookhaven National Laboratory, Upton NY, USA.

In comparison to water, little is known about the diverse radiation chemistry presented

by organic solvents. We are particularly interested in the early-time (sub-ns to ns) chemistry

of holes (radical cations) formed by radiolysis: What is their nature, what can they oxidize, and

how fast? How do these processes shape long-time chemistry? Holes in organic liquids are

known to fragment, rapidly in some cases. Can we learn to control or block this chemistry?

The work that I will describe focuses on understanding ways to oxidize of solutes after

radiolysis very rapidly, to enable picosecond observation of processes like charge transfer and

transport. Holes produced by radiolysis have typically been considered as molecular ions that

move by diffusion, a slow process. While electrons in some liquids are known to be captured

at rates exceeding 1013 M-1s-1, as well as prior to solvation under certain circumstances, such

mechanisms are not generally known for holes. This work challenges the long-held perception

of the nature of holes at early times in organic liquids and finds substantial sub-15 ps capture.

I will show examples in 3 different classes of organic solvents: those known to form

solute radical cations only (chloroform), those where they are normally not formed (THF), and

those known to form both solute anions and cations (alkanes). The common finding in all 3

media is that there are solute radical cations formed within our ~10-15 ps time resolution at the

Laser Electron Accelerator Facility (LEAF, BNL).

The figure shows an example in n-pentane. The

sudden or “step” increase in transient absorption at

t~0 is due to the < 15 ps production of solute radical

cations and is followed by an additional growth due

to normal diffusion. This “step capture” produces

solute+● much faster than diffusion, with substantial

yields. We would like to understand the mechanism

by which it occurs, and whether it might play a

fundamental role in radiolysis. Data have been

successfully modeled using formalisms previously

used for the capture of pre-solvated electrons,

suggesting that there may be parallel mechanisms

for holes. I find that the efficiency of this process

rivals that for pre-solvated electrons in chloroform

and alkanes, and the models give average capture distances across multiple solvent molecules

in these solvents, while in THF is limited to capture from nearest neighbors.

Work thus far suggest that the process may be best described as capture of the precursor

to solvent radical cations, likely a form of pre-solvated holes. As such, it likely is important in

a wider variety of media, particularly when solute concentration is large. I will show some

examples of how this has manifested in our work in charge transport projects, and how it might

be used to produce desired solute radical cations in media like ethers and possibly block

fragmentation of holes.

Ref: Cook, A. R.; Bird, M. J.; Asaoka, S.; Miller, J. R. J. Phys. Chem. A 2013, 117, 7712-7720.



37

I13: Radiation Energy Transfer Simulation toward Extraction Solvent in

Minor Actinide Separation Process

T. Toigawa, Y. Tsubata, T. Kai, T. Furuta, Y. Kumagai, T. Matsumura

Japan Atomic Energy Agency, Ibaraki, Japan.

The long-term radioactive toxicity of high-level liquid waste (HLLW) mainly depends on

minor actinides (MAs: Am and Cm). For the reduction of the toxicity, Japan Atomic Energy

Agency developed a highly effective extraction ligand, N,N,N’,N’-tetraoctyl diglycolamide

(TODGA), which can extract MAs and lanthanides from nitric acid media [1]. The radiation

stability of TODGA has also been studied in terms of the radiation chemical information such

as the degradation yield of TODGA or the changes of the extraction ability for MAs. However,

the radiation dose absorbed by the extraction solvent containing TODGA is still unclear in a

real MA separation process because of the experimental difficulty of the dosimetry. Therefore,

it is necessary to estimate the absorbed dose supposing actual conditions of the process. In the

extraction process, the extraction solvent is vigorously stirred with HLLW containing various

radionuclides and forms inhomogeneous oil-water mixture. This mixed state is expected to

affect the absorbed dose distribution because the scale of the mixed state may be comparable

with the ranges of α-rays and low-energy electrons. A reliable estimation should take into

consideration this effect as well as the concentrations of radioactive nuclides in the HLLW and

their decay modes. In this study, we focused on

this radiation permeability effects on the

separation process. A radiation energy transfer

simulation in the inhomogeneous structures was

performed with the aid of the Monte Carlo

radiation transport code, PHITS [3].

The extraction solvent and the HLLW were

assumed as 0.1 M TODGA-dodecane solution

and 3 M nitric acid aqueous solution. The

radioactive concentrations in HLLW were 1.7 ×

1011, 1.6 × 1013 and 7.5 × 1012 Bq/L for α-, β- and

γ-ray emitters, respectively. Fig. 1 shows the

calculation result of the absorbed dose rate in the

extraction solvent as a function of the dispersed droplet size in the infinitely spread emulsion.

If the droplet size was significantly small compared to the radiation travel distance, the ratio of

energy deposition to the extraction solvent and the HLLW seems to be homogeneous. Because

TODGA extracted almost all the α-emitters and the strong β-emitters such as 90Y, and 144Pr,

the absorbed dose for α- and β-ray increased with the droplet size after extraction. On the other

hand, the absorbed dose for γ-ray decreased with the droplet size because the γ-emitters were

not extracted by TODGA. The absorbed dose for γ-ray was mainly due to the contribution of

the γ-emitters remaining in the HLLW. A significant contribution of low LET radiation for the

extraction solvent was pointed out in terms of the absorbed dose.

References

1. Sasaki, Y. et al. (2007) Extraction of Various Metal Ions from Nitric Acid to n-dodecanen by

Diglycolamide (DGA) Compounds, J. Nucl. Sci. Tech., 44, 405-09

2. Sugo, Y. et al. (2009) Radiolysis study of actinide complexing agent by irradiation with helium ion

beam, Radiat. Phys. Chem., 78, 1140-114

3. Sato, T. et al. (2018) Features of Particle and Heavy Ion Transport code System (PHITS) version

3.02, J. Nucl. Sci. Technol., 55, 684-690

Figure 1 absorbed dose rate in the extraction solvent mixed with the HLLW.

3000

2000

1000

0

Ab

so

rbe

d d

ose

in

org

an

ic p

ha

se

/ G

y h

-1

1 µm 10 µm 100 µm 1 mm 10 mm 100 mm 1 m

Droplet diameter

Alpha

Beta Gamma

before extraction

after extraction

after extraction

before extraction

after extraction

before extraction



38

P12: Effect of Supports on Metal-Nanoparticle Catalysts: The Radiolytic

H2 Evolution Reaction

Gifty Sara Rolly,1 Ronen Bar-Ziv 2 and Tomer Zidki 1

1Department of Chemical Sciences, Ariel University, Ariel, Israel; 2Department of Chemistry, Nuclear Research Centre Negev, Beer-Sheva, Israel.

The performance of the silica-supported M0 nanoparticles as catalysts for water reduction was

studied using the strongly-reducing ·C(CH3)2OH radicals at acidic and alkaline media. It was

found that supporting metal nanoparticles (M0-NPs, M = Pt, Au, Ag) on an "inert" support such

as SiO2 alters the catalytic properties of the metals. This effect depends both on the nature of

M and on the concentration of the composite nanoparticles. At low nanocomposite

concentration: for M = Au nearly no effect is observed; for M = Ag the support decreases the

catalytic reduction of water, and for M = Pt the support initiates the catalytic process. At high

nanocomposite concentration: for M = Au the reactivity is considerably lower, and for M = Ag

or Pt, no catalysis is observed. Furthermore, for M = Ag or Pt H2 reduces the ·C(CH3)2OH

radicals. Changing the medium from alkaline to acidic pH did not affect these trends.

Therefore, we conclude that the metal oxide support affects the M0-NPs redox properties.

Below is the proposed mechanism pathways for the production of H2 and the deactivation of

H2 evolution.



39

P13: Radiation-Induced Redox Chemistry of Californium-249

David S. Meeker1,2, Gregory P. Horne1, Travis S. Grimes1, Peter R. Zalupski1, James F. Wishart3,

Stephen P. Mezyk4, and Thomas E. Albrecht-Schmitt2

1 Idaho National Laboratory, Center for Radiation Chemistry Research, Idaho Falls, ID, P.O. Box

1625, 83415, USA 2 Florida State University, Department of Chemistry and Biochemistry, Tallahassee, FL, 32306-4390,

USA. 3 Brookhaven National Laboratory, Department of Chemistry, Upton, New York, 11973, USA.

4`California State University Long Beach, Department of Chemistry and Biochemistry, Long Beach,

CA 90804, USA.

A complete understanding of californium chemistry necessitates knowledge of its

radiation-induced redox behavior, owing to its inherent nuclear instability propagating self-

radiolysis. Only a handful of studies have investigated californium radiation chemistry, due to

lack of element availability and difficulty associated with handling highly radioactive material.

To date, reaction rate coefficients (k) have only been experimentally determined for the

reduction of Cf(III) by the hydrated electron (e¯aq, k > 3 × 109 M–1 s–1) from water radiolysis,

and subsequent decay of the corresponding transient Cf(II) (k = (7 ± 1) × 105 s–1)[1]. However,

there are a number of other important transient radiolysis products radiolytically generated in

solutions pertinent to californium manipulations, e.g., the hydrogen atom (H•, Eo = 2.31 V),

hydroxyl radical (•OH, Eo = –2.73 V), and nitrate radical (•NO3, Eo = –2.3 – –2.6 V). These

species are more than capable of influencing the redox behavior of californium, and have been

shown to do so with a number of actinides, e.g., neptunium and americium.[1,1,1] Here we

present the results from the first time-resolved picosecond pulsed electron radiolysis

measurements for californium-249. The reaction rate coefficients were determined by direct

decay of the observed species or via competition kinetics. For the reductive reactions of Cf(III)

with the e¯aq and H• transients, the reaction rate coefficients were measured to be (7.11 ± 0.18)

× 1010 and (2.61 ± 0.54) × 108 M−1 s−1, respectively, while studies for the oxidation of Cf(III)

by the •NO3 and •OH species yielded (2.0 ± 0.5) × 108 and (7.2 ± 0.6) × 108 M−1 s−1, respectively

References

1. Sullivan, J.; Morss, L.; Schmidt, K.; Mulac, W.; Gordon, S. Pulse Radiolysis Studies of

Californium (III) in Aqueous Perchlorate Solution. Evidence for the Preparation of Californium

(II). Inorg. Chem., 1983, 22, 2339.

2. Horne, G. P.; Grimes, T. S.; Mincher, B. J.; Mezyk, S. P. Re-evaluation of Neptunium-Nitric

Acid Chemistry by Multi-Scale Modelling. Journal of Physical Chemistry B, 2016, 120 (49),

12643–12649.

3. Grimes, T. S.; Horne, G. P.; Dares, C. J.; Pimblott, S. M.; Mezyk, S. P.; Mincher, B. J. Kinetics

of the Autoreduction of Hexavalent Americium in Aqueous Nitric Acid. Inorganic Chemistry,

2017, 56 (14), 8295-8301.

4. Horne, G. P.; Grimes, T. S.; Bauer, W. F.; Dares, C. J.; Pimblott, S. M.; Mezyk, S. P.; Mincher,

B. J., Effect of Ionizing Radiation on the Redox Chemistry of Penta- and Hexavalent

Americium. Inorganic Chemistry, submitted 28th March 2019.



40

I14: Capturing Sunlight with Molecular Systems – A Pulse Radiolysis

Investigation into Charge Recombination and Escape for Solar Energy

Conversion

M. Jilek1, J. Keiper2, J. Burke3 and M. Bird4

1University of Colorado Boulder, CO 80309-0215 Boulder, CO, USA. 2Penn State University, University Park, PA 16802, USA.

3University of Illinois at Urbana–Champaign, 505 South Mathews Avenue

Urbana, IL 61801, USA. 4Brookhaven National Laboratory, Upton, NY 11973, USA.

Solar cells based on thin films of donor (D) and

acceptor (A) molecules (organic photovoltaics) have

recently reached power conversion efficiencies as high

16.5 % [1]. This remarkable performance occurs

despite the fact that photogenerated charge pairs, in a

nonpolar film, should have difficulty escaping their

mutual coulombic attraction to reach the electrodes.

These materials are typically highly conjugated,

allowing for significant charge delocalization. While

some general material design rules have been

established, there is still a lack of basic understanding

about the exact role of delocalization, spin, and local

excited states in non-radiative charge recombination;

the main source of energy loss in these devices.

Information about charge recombination and escape

can obtained from photoinduced absorption (PIA) of

DA films but this has limitations inherent to the

disordered nature of films. Pulse radiolysis offers a

complementary technique where fundamental steps

can be isolated and studied in the similar environment

of nonpolar solvents.

Pulse radiolysis enables a known concentration of charges and/or excited states to be rapidly

created in the solvent, regardless of what the solute is. With transient absorption spectroscopy

(TAS) in the UVvis/nearIR/microwave, the rate of transfer of energy and/or charge to the solute

and between solutes can be studied.

We have used pulse radiolysis to learn about the thermodynamics and kinetics of charge pair

formation and recombination. We have investigated the role of spin in charge recombination

be looking at recombination of charge pairs with energy above and below local triplet excited

states (green and red respectively in figure 1). We have found some surprisingly long lifetimes

of microseconds for some radical cation and anion pairs.

We complement these pulse radiolysis techniques with ground state charge transfer

experiments to study the electrostatic interaction between delocalized charges in conjugated

polymers. We have also determined the thermodynamics of electron transfer and escape when

one of the charges is highly delocalized in conjugated polymer “nanowire” aggregates.[2]

Reference(s)

1. https://www.nrel.gov/pv/assets/pdfs/best-research-cell-efficiencies.20190802.pdf

2. J. H. Burke, M. J. Bird, Adv. Mater. 2019, 1806863

Figure 1. Transient absorption of

fluorene (F1) cations as they

recombine with benzoquinone (BQ)

or tetracyanoethylene (TCNE) anions

following pulse radiolysis.



41

I15: Drastic Changes in the Surface Reactivity of UO2-Based Spent Nuclear

Fuel upon Exposure to Radiolytic Oxidants – How Will This Influence the

Safety Assessment of Deep Geological Repositories for Spent Nuclear Fuel?

A. C. Maier and M. Jonsson*

Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden

Several countries plan to store their spent nuclear fuel in deep geological repositories for

extremely long time periods (>100000 years). This calls for rather extreme safety assessments

accounting for a multitude of possible scenarios. A commonly used scenario is groundwater

intrusion into a fuel canister after 1000 years. Since UO2 (the matrix of the most commonly

occurring spent nuclear fuel) has very low solubility in the reducing groundwater expected to

be found at the depth of a typical repository, the main process driving the fuel matrix

dissolution and the subsequent release of fission products and heavier actinides is radiolysis of

groundwater. The oxidants produced upon radiolysis of groundwater are capable of oxidizing

U(IV) to the considerably more soluble U(VI) and thereby solubilize the fuel matrix. Previous

studies have shown that the most important oxidant in these systems is H2O2. To assess the

long-term leaching behavior of UO2, the oxidative dissolution of UO2 pellets was studied at

high H2O2 exposures (expressed as amount of oxidant consumed per surface area) ranging from

0.3 mol m-2 to 1.4 mol m-2. The results indicate that the dissolution yield (amount of dissolved

uranium per consumed H2O2) at high H2O2 exposures is significantly lower compared to

previous studies of both pellets and powders and decreases for each H2O2 addition for a given

pellet. This implies a change in redox reactivity by a factor of three to four, which is attributed

to irreversible alteration of the pellet surface. Surface characterization after the exposure to

H2O2, by SEM, XRD and Raman spectroscopy show, that the surface of all pellets is

significantly oxidized.

The same type of study was also performed on Gd-doped UO2 (Gd is used as a burnable neutron

absorber in commercial nuclear fuel) revealing similar trends at different doping levels. The

results of the studies performed on pure UO2-pellets and Gd-doped UO2-pellets are discussed

in combination with relatively recent findings on the reactivity of UO2-powder (exposed to

H2O2 as well as ionizing radiation) as a function of stoichiometry. Finally, the overall impact

of these findings on the safety assessment for deep geological repositories for spent nuclear

fuel is discussed.



42

P14: Reduction of Cobaoxime-Based Complexes: Mechanisms, Products

and Implications

A. Kahnt1, E. Hofmeister2, T. Ullrich3, K. Hanus1 and M. von Delius2

1Leibniz Institute of Surface Engineering (IOM), Leipzig, Germany. 2Institute of Organic Chemistry and Advanced Materials, University of Ulm, Ulm, Germany.

3Chair of Physical Chemistry I, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.

Cobaltoxime based complexes have attracted strong interest in the past and present. Decades

ago the focus was set on alkyl and alkenyl cobaloximes as vitamin B12 model system1. Later,

new interest arose regarding this class of compounds owing to the fact that Co(dmgBF2)2

catalyses the reduction of protons in acidic solutions.2 In this regard, cobaloxime complexes

are considered as candidates for the “Holy Grail” in the field of renewable energy - that is the

formation of renewable fuel from solar energy, to potentially meet the future energy demands

without the use of fossil fuel. Several cobaltoxime based systems containing organic and/or

inorganic chromophores3 for light harvesting have been coordinated to the cobalt centre of

cobaloxime complexes and have been successfully tested for the photocatalytic reduction of

water.

But, plenty of this systems prompt to a up to hours lasting induction period for the

photocatalytic reduction of water.4 Surprisingly, the reasons for such a phenomenon remain

largely unknown4 and comes hardly in line with the usual

proposed reaction mechanisms postulating a reduction

from a CoIII to a CoI species. Our past work5,6 related to

photocatalytic water reduction triggered our interest in the

understanding of this mechanism. In line with the latter,

we conducted a full fledge spectroscopic and kinetic

investigation of the reduction of mono-nuclear Co-

complexes by pulse radiolysis assays, however, we found

solid evidence that a final product of the reduction process

was a dinuclear complex.6 From this finding we derived

the implication that for an efficient induction period free

photo-catalysts least two Co-centres like in the CoIII double salt presented in figure 1 are

required. For these new and very efficient class of proton reduction photo-catalysts detailed

investigations of the reduction mechanism by pulse radiolysis were conducted in order to

establish the mechanism behind the found quite efficient proton reduction.7

Reference(s) 1. Prince R.H., Segal, M.G. (1974) Nature, 249, 246-247.

2. Connolly P., Espensson J.H. (1986) Inorg. Chem., 25, 2684-2688.

3. Artero V., Fontecave M. (2013) Chem. Soc. Rev., 42, 2338-2356.

4. Du P., Eisenberg R. (2012) Energy Environ. Sci., 5, 6012-6021.

5. Peuntinger K., Lazarides T., Daphnomili D., Charalambidis G., Landrou G., Kahnt A., Sabatini R.,

McCamant D., Gryko D.T., Coutsolelos A., Guldi D. M. (2013) J. Phys. Chem. C, 117, 1647-1655.

6. Kahnt A., Peuntinger K., Dammann C., Drewello T., Hermann R., Naumov S., Abel B., Guldi D.

M. (2014) J. Phys. Chem. A, 118, 4382-4391.

7. Hofmeister, E., Ullrich, T., Petermann L., Hanus, K., Rau, S., Kahnt, A., von Delius, M. (2019)

Angew. Chem. Int. Ed., under preparation.

Figure1. New generation of

Co-double salts as core

structure for novel proton

reduction photo-catalysts [7].



43

I16: Heterogeneous Alteration of a Mimas MOX Fuel under Oxidizing

Conditions Revealed by Raman Spectroscopy

L. Sarrasin, S. Miro, C. Jégou, V. Broudic, C. Marques, M. Tribet, S. Peuget

Commissariat à l’Énergie Atomique (CEA), Marcoule Research Center, BP 17171, F-30207 Bagnols-sur-Cèze Cedex, France

In view of interim wet storage of MOX fuel assemblies for several decades the prospect of a

through-wall cladding defect must be considered. In the event of a failed fuel rod, the main

objective is to determine the potential impact of the formation of secondary phases or an

oxidized layer on the mechanical properties of the cladding. The irradiation conditions

expected in a fuel storage pool (high dose rate in the fuel assembly and contact with aerated

water) will be favorable to the recombination kinetics in favor of the molecular species like

hydrogen peroxide liable to enhance oxidizing dissolution of the fuel matrix near the defect.

Un-irradiated heterogeneous MOX07 pellets (MIMAS MOX 7% Pu/(U+Pu)) were leached in

aerated water under a gamma source (60Co) in a hot cell in order to reproduce as closely as

possible the radiation field inside a fuel assembly. The initial microstructure observed on this

type of MOX fuel revealed the presence of different zones with different Pu contents arising

from the fabrication process. The leachate was regularly sampled for elemental and

radiochemical analysis, the pH and redox potential were measured and hydrogen peroxide, a

molecular product generated by water radiolysis, was analyzed. The MOX samples were

analysed using Raman spectroscopy over time during the 3 months of the leaching experiments.

Localized and punctual spectra as well as mappings of the samples were acquired in order to

follow the surface’s evolution and link it to the local heterogeneities of the MOX

microstructure. This experiment was followed by a second one performed under the same

experimental conditions but with an enriched water at 97% in 18O. The Raman spectroscopy

being sensitive to mass variations, the 18O of this experiment acts as a marker for the oxidation

and/or phase formation at the sample’s surface.

We have demonstrated thanks to Raman mappings the heterogeneity of the alteration through

a preferential corrosion of the UO2 grains and through the local formation of secondary phases.

The uranium-rich zones are dissolved prior to Pu-rich aggregates, which creates holes at the

surface of the samples. These holes are preferential sites for the precipitation of studtite that

covers the whole surface in the long term. To better understand the mechanisms of studtite

formation and oxidation, marked water was used. The first results are presented and discussed.

Figure 1: Heterogeneous precipitation of studtite on U-rich zones of a MOX07 sample after 20

days of leaching; a) optical image b) Raman mapping and c) Raman spectra of the surface

200 400 600 800 1000 1200 1400 1600

Inte

nsi

ty (

a.u

.)

Wavenumbers (cm-1)



44

I17: Heavy Ion-Induced Defect Production in Single-, Few-Layer and Bulk

Crystals of MoS2

Liam H. Isherwood,1,2 Cinzia Casiraghi1 and Aliaksandr Baidak1,2

1 Chemistry Department, School of Natural Sciences, University of Manchester, Manchester, M13 9PL, United Kingdom

2 Dalton Cumbrian Facility, University of Manchester, Westlakes Science Park, Cumbria, CA24 3HA,

United Kingdom

Two-dimensional (2D) MoS2 has attracted

a great deal of research interest on account of its

1.9 eV direct bandgap and catalytically active

edge sites which make it a promising candidate

for flexible and transparent (opto)electronic

devices [1] as well as catalytic applications [2].

Ion beam-mediated defect engineering is a

powerful tool to tailor the properties of 2D

MoS2 [3] on account of its unique spatial

resolution and the plethora of ion types and

energies available. In order to fully realise the

potential of this technique, a holistic

understanding of ion-induced defect production

in MoS2 is required.

This presentation will evaluate defect production in monolayer MoS2 fabricated by both

micromechanical exfoliation (MME) and chemical vapour deposition (CVD) as well as MoS2

crystals of various thicknesses. Raman spectroscopy, x-ray photoelectron spectroscopy and

electron diffraction are used to characterise the radiation-induced changes in MoS2 crystals

under 225 keV Xe+ ion irradiation.

All three techniques show that the rate of defect production is inversely proportional the

thickness of the crystal whilst Raman spectroscopy shows that the rate is comparable for

monolayer MoS2 produced by either MME or CVD. Both monolayer and bulk MoS2 become

p-doped after irradiation and the out-of-plane vibrational properties of defective MoS2 are

progressively dominated by interlayer interactions in thicker crystals. Specifically, the

frequency of the out-of-plane 𝐴1𝑔 mode blueshifts in monolayer MoS2 due to phonon

confinement effects whilst a redshift is observed in bulk MoS2 and is attributed to attenuation

of the effective restoring forces acting on S atoms due to reduced interlayer interactions (Fig.

1). Moreover, the phonon lifetime of this mode is increased in irradiated few-layer MoS2 and

is tentatively attributed radiation-induced decoupling of the individual monolayers.

Our results further support the use of ion beams for defect engineering of MoS2 and offer

valuable insights into how the dimensionality of layered crystals influences the evolution of

their electronic, vibrational and structural properties under heavy ion irradiation.

References:

1. De Fazio, D., Goykhman, I., Yoon, D., Bruna, M., Eiden, A., Milana, S., Sassi, U., Barbone, M.,

Dumcenco, D., Marinov. K., Kis, A. and Ferrari, A.C., (2016), ACS Nano, 10, pp. 8252-8262

2. Xie, J., Zhang, H., Li, S., Wang, R., Sun, X., Zhou, M., Zhou, J., Wen, X., Lou, D. and Xie, Y.,

(2013), Adv. Mater., 25, pp. 5807-5813 3. He, Z., Zhao, R., Chen, X., Chen, H., Zhu, Y., Su., H., Huang, S., Xue, J., Dai, J., Cheng, S., Liu, M.,

Wang, X. and Chen, Y., (2018), ACS Appl. Mater. Interfaces, 10, pp. 42524-42533

Figure 5: The relative frequency shift (∆𝜈) of the out-

of-plane 𝐴1𝑔 mode of monolayer MoS2 (2D MoS2) and

bulk MoS2 (3D MoS2) crystals, produced by

micromechanical exfoliation, as a function of radiation

exposure.



45

P15: γ-Radiolysis of Thermal Transition Phases in Boehmite

Patricia L. Huestis1 and Jay A. LaVerne1

1Department of Physics and Notre Dame Radiation Laboratory, University of Notre Dame, Notre

Dame, IN, USA.

Over 200 million liters of high level waste (HLW) reside in the Hanford Waste Tanks. These

tanks contain legacy waste from the Cold War era and are chemically complex due to high

nitrate concentrations, high pH, and large radiation fields. Boehmite (γ-AlOOH) is a large

component of the solid waste located within the tanks and is especially problematic due to its

longer than predicted dissolution times. Boehmite has a layered structure which consists of an

Al-O lattice hydrogen bonded together via bridging OH groups. The mechanism responsible

for hydrogen production in boehmite is still not well understood.

Boehmite was heated to various temperatures along its dehydration pathway to assess the

structural differences and their effect on the radiolysis of boehmite. Structural changes were

investigated using powder X-Ray Diffraction (pXRD), Raman spectroscopy, nitrogen

adsoption, and Scanning Electron Microscopy (SEM). Radiolytic effects were assessed using

Gas Chromatography (GC) and Electron Paramagnetic Resonance (EPR). Different sizes of

materials were used to investigate the size dependence on the thermal degradation and its effect

on the creation of radiolytic products by gamma rays.

The yield of H2 with respect to energy deposited into the material/water system is nearly

constant for both sizes of material heated below 300°C with the smaller material having a

slightly higher yield. The larger material, when preheated further to 400°C, shows a dramatic

increase in H2 production. Larger material preheated to 550°C as well as smaller material

preheated to both 400°C and 550°C shows a yield consistent with alumina, indicating complete

or near complete dehydration. Initial production of trapped hydrogen radicals within the larger

material in conjunction with the yield for the sample preheated to 400°C suggest that the

hydrogen production mechanism is likely an abstraction reaction by H atoms with surface water

as opposed to a bimolecular combination reaction.



46

P16: Key Role of the Oxidized Citrate Free Radical in the Nucleation

Mechanism of the Metal Nanoparticles Turkevich Synthesis

Sarah Al Gharib,1,2, Jean-Louis Marignier,1 Adnan Naja,2 Abdel Karim El Omar,2 Sophie Le

Caer,3 Mehran Mostafavi,1 and Jacqueline Belloni1.

1 Laboratoire de Chimie-Physique/ELYSE, UMR 8000 CNRS/UPS, Université Paris Sud, Université Paris-Saclay, Bât. 349, F-91405 Orsay Cedex, France.

2 Laboratoire Physique et Modélisation, Université Libanaise, Tripoli, Lebanon. 3 Laboratoire LIONS, DSM/IRAMIS/NIMBE UMR 3685 CNRS/CEA/Saclay, Université Paris-Saclay,

Bât. 546, F-91191 Gif-sur-Yvette, Cedex, France.

The step-by-step mechanism of the citrate oxidation, of the silver ion reduction [1] [2] into

atoms, and of the nucleation of nanoparticles by the Turkevich method [3] are deduced from

the gamma- and pulse radiolysis yields of dicarboxy acetone (DCA), H2 and CO2 and of silver

ion reduction. Our results demonstrate that the stronger reductant is not citrate (Cit) but the

oxidized radical Cit(-H)•. The formation yields of DCA and CO2 confirm the decarboxylation

process during the Cit(-H)• oxidation. In pulse radiolysis of solutions of sodium citrate and

silver perchlorate, the transient spectra [4] and the kinetics are observed from 20 ps to 800 ms.

In particular, the successive H abstraction from citrate by OH• radicals, then the one-electron

transfer from the citrate radicals Cit(-H)• to silver ions initiating the simultaneous nucleation

and growth of the reduced silver oligomers are observed. The knowledge of the nuclearity-

dependent kinetics and thermodynamics of silver atoms, oligomers and nanoparticles in

solution is used to bracket the standard reduction potentials of the first (≥ 0.4 VNHE) [2] and the

second one-electron transfers from citrate (≤ - 1.2 VNHE) [2]. During the Turkevich synthesis,

the Cit(-H)• radical was shown to be released in the bulk solution from the citrate oxidation by

Ag+ adsorbed on the walls (Figure 1), or directly by the trivalent AuIII ions present in the bulk,

respectively. Then the strong Cit(-H)• reductant alone is able, as in radiolysis, to overcome the

thermodynamic barrier of the very negative potential for the reduction of the free monovalent

ions into atoms that is required to initiate the nucleation and growth (Figure1). The reduction

potentials values of citrate and Cit(-H)• also explain part of the antioxidant properties of citrate.

Reference(s)

1. Marignier, J.L;. Belloni, J. ; Delcourt, M.O. ; Chevalier, J.P Nature, 1985, 317, 344-345.

2. Belloni J., Mostafavi, M., Radiation Chemistry of Clusters and nanocolloids. In Studies in

physical and theoretical chemistry, Radiation Chemistry:, Jonah, C.D. ; Rao, M. (eds), Elsevier,

2001, 87, 411-452.

3. Turkevich, J.; Stevenson, P.C.; Hillier, J. Disc. Faraday Soc. 1951, 55-75.

4. Simic, M.; Neta, P.; Hayon, E. J. Phys. Chem. 1969, 73, 4214-4219.



47

I18: The Effects of Gamma Radiation on the Accelerated Carbonation of

Fly-Ash Blended Cement

A. Potts1, E. Butcher2, G. Cann2, L. Leay1

1 Dalton Cumbrian Facility, The University of Manchester

2 National Nuclear Laboratory

Both gamma irradiation and carbonation are known to induce long term aging effects occurring

within concrete structures in nuclear facilities. Previous studies have shown that the coupling

of these two mechanisms leads not only to an increase in the carbonation depth [1-2] but also

a change in the primary carbonation product formed [3]. In this talk, we present the

experimental results addressing this coupling effect.

Carbonation occurs as CO2 diffuses into the cement pore water, reacting with calcium-

containing phases such as calcium hydroxide to form calcium carbonate:

Ca(OH)2 + CO2 → CaCO3 + H2O

This process involves the dissolution of calcium cations from the crystalline phase and

carbonate anions into the alkaline pore water. Calcium carbonate exists as polymorphs: calcite

(most thermodynamically stable), aragonite and vaterite (least thermodynamically stable).

Our experiment was conducted sequentially: 1.2 MGy gamma irradiation under atmospheric

conditions and 50 °C followed by carbonation in a 5% CO2 atmosphere at room temperature.

A heat treated unirradiated sample was also analysed for comparison. The XRD heatmaps

below show that both the irradiated and heat-treated samples exhibit an increased depth of

carbonation compared to the control, as well as a switch in carbonation phase from vaterite to

calcite. Our results suggest that both heat and irradiation cause a long-lasting change in the

cement leading to an alternative carbonation pathway.

Irradiated then carbonated Heated then carbonated Control (carbonated only)

P= Portlandite (calcium hydroxide), Q = quartz, V= Vaterite, A = Aragonite, C = Calcite

and C-S-H is calcium-silicate-hydrate

Currently, other researchers hypothesise that advanced dehydration is the mechanism for

irradiation accelerated carbonation. A radical chemistry route leading to calcium hydroxide

formation has also been discussed. Our data implies that there are subtle differences in the

irradiated and heat treated samples. Further analysis involves SEM-EDS characterisation to

gain an insight into the morphology of the carbonate phases as well as pore water chemical

analysis.

Reference(s)

1. Vodák, F, Vydra V, Trtík, K, and Kapicková O. (2011) Effect of Gamma Irradiation on Properties

of Hardened Cement Paste Materials and Structures 44 (1): 101–7.

2. Bar-Nes, G, Katz, Peled, Y and Zeiri, Y (2008) The combined effect of radiation and carbonation

on the immobilization of Sr and Cs in cementitious pastes Materials and Structures 41: 1563-

1570

3. Maruyama, I, Shunsuke I, Junichi Y, Shohei S, and Ryo K. (2018) Impact of Gamma-Ray

Irradiation on Hardened White Portland Cement Pastes Exposed to Atmosphere Cement and Concrete Research 108 (June 2017): 59–71.



48

P17: The Radiation Chemistry of Aqueous PVP Solutions Exposed to

Pulsed E-beam Irradiation: Experiments and Numerical Simulations

C. Dispenza1, M. A. Sabatino1, B. Dahlgren2, M. Jonsson2

1Department of Engineering, University of Palermo, Italy. 2Department of Chemistry, KTH Royal Institute of Technology, Sweden.

Nanogels have recently raised considerable interest in the biomedical field, due to their diverse

applications in tissue engineering, regenerative medicine and drug delivery.

One-pot radiation-induced synthesis of nanogels from dilute aqueous polymer solutions is one

example of a process that has been successfully carried out using electron accelerators equipped

with scanning horn and a conveyor belt. In dilute aqueous systems the radiation energy is

mainly absorbed by water. Upon exposure to ionizing radiation, water is decomposed into OH,

H, eaq-, H2, H2O2 and H3O+. Polymer radicals are formed upon hydrogen abstraction from the

polymer by OH and H. By saturating the aqueous solution with N2O, the strongly reducing

hydrated electron can be converted into a hydroxyl radical.

In the radiation synthesis of nanogels from polymer aqueous solutions, conditions that favor

intramolecular radical-radical reactions are generally employed. Interestingly, these are also

the conditions when scavenging of the primary radicals formed in the radiolysis of water is no

longer quantitative. Under these conditions, a fraction of the hydroxyl radicals can recombine

and produce hydrogen peroxide. This can have a significant influence on the further reactions

in the system. In systems exposed to a sequence of pulses, the formation of H2O2 will eventually

lead to the production of O2. It is therefore desirable to be able to perform both experiments

and numerical simulations on these systems both in order to confirm mechanistic and kinetic

data and to be used as a predictive tool for process optimization.

The obvious first step in the development of the modelling tool is the simulation of single pulse

irradiations to explore the effects of dose per pulse, concentration of polymer and polymer

molecular weight on the kinetics of polymer radical decay. The next step is to model more

complex pulse sequences that resemble conditions used to irradiate large volumes of aqueous

polymer solutions and produce nanogels.

The numerical simulation is based on a deterministic approach encompassing the conventional

homogeneous radiation chemistry of water as well as chemical reactions involving polymer

chains and polymer radicals. As benchmarking, results from a series of experiments on pulsed

irradiation of aqueous PVP-solutions have been used. The simulations qualitatively reproduce

the experimentally observed impact of initial gas saturation (air and N2O) and polymer

concentration on the molecular chain length upon irradiation. The formation of double bonds

as a function of dose as well as the impact of effective dose rate on the final chain length are

also qualitatively reproduced in the simulations and suggests different possible options for

irradiation conditions to tailor the molecular weight and functionality of the synthetized

nanogels to meet application requirements.

Acknowledgements

BD acknowledges the Royal Institute of Technology for financial support.

CD acknowledges the Institute of Nuclear Chemistry and Technology in Warsaw (Poland) for

performing the ebeam irradiations and IAEA CRP F22064.



49

P18: Internal Structure and Composition of Fukushima-Derived

Particulate Revealed through Combined Synchrotron and Mass-

Spectrometry Techniques

P.G. Martin1, S. Cipiccia2, D.J. Batey2, Y. Satou3 and T.B. Scott1

1School of Physics, University of Bristol, HH Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8

1TL 2Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE

3Japan Atomic Energy Agency (JAEA) - CLADS, Tomioka, Futaba-gun, Fukushima Prefecture, Japan

Despite the events at the Fukushima Daiichi Nuclear Power Plant (FDNPP) having passed

their eighth anniversary, a considerable amount of work is still ongoing to evaluate

the nature and environmental legacy of the radioactive particulate species [1,2].

Through the application of both laboratory and synchrotron radiation (SR) x-ray tomography

(XRT), the internal structure of a representative sub-mm particle was shown to be highly-

porous – with 24% of the internal volume constituted by void space (Figure 1). Compositional

(elemental) analysis of the particulate material through SR x-ray fluorescence (XRF) detailed

the peripheral enrichment of several elements (including Sr, Pb and Zr). The component of

fissionogenic Cs (134 + 135 + 137Cs) was determined to account for most of the elemental

abundance within the particle with limited contribution from natural 133Cs.

SR x-ray absorption near edge structure (XANES) analysis on several high atomic density

particles located within the bulk particle confirmed them to be U in composition, existing in

the U(IV) oxidation-state, as UO2. The complementary isotopic analysis of this micron scale

uranium material enclosed just below the surface of the particle was subsequently determined

using secondary ion mass spectrometry (SIMS), having spatially referenced their co-ordinate

positions between the different techniques. SIMS mapping revealed the U-rich particle to be

~1 μm in maximum dimension, consisting of enriched U with 3.54 wt% 235U – analogous to

that used in the reactor Unit 1 fuel assemblies [3].

References

[1] Imoto et al., (2017). Scientific Reports, 7 (5409) pp. 12.

[2] Furuki et al., (2017). Scientific Reports, 7 (42731) pp. 10. [3] Fukushima Daiichi NPS - Information Portal. TEPCO (2013).

Figure 1. SR-XRT reconstruction of the representative particle showing the 24% void volume.

Regions of both stainless-steel (orange) and cement (green) composition are shown (as identified

through SR-XRF), as are locations where voids are observed to interact.



50



51

TUESDAY 10TH SEPTEMBER 18:00-19:00

POSTER SESSION 1

(EVEN NUMBERS)



52

Poster 2: Impact of Doping and Functionalisation of Graphene Support on

the Radiolytic Synthesis of Palladium Nanoparticles for Electrocatalysis

Kun Guo1,2 and Aliaksandr Baidak1,2

1School of Chemistry, The University of Manchester, Manchester M13 9PL, UK;

2Dalton Cumbrian Facility, The University of Manchester, Moor Row CA24 3HA, UK.

Gamma radiolysis of common solvents, including ethylene glycol, is known to generate strong

reducing species such as solvated electron, hydrogen atom and carbon-centred radicals. This

mechanism provides a green and facile route to synthesize colloidal metal nanoparticles (NPs)

immobilized on graphene-based supports. However, controlling the NP size and size

distribution remain challenging. Hereby we investigate the impact of heteroatom doping and

functionalisation of graphene-based supports on tackling such challenges. Four types of

graphene materials, namely graphene oxide (GO), reduced graphene oxide (rGO), graphene

(G), and nitrogen-doped graphene (N-G), are utilised to immobilize palladium (Pd) NPs, which

are obtained by γ-radiation-induced reduction in ethylene glycol. The as-prepared composites

are then evaluated in the electrocatalytic hydrogen evolution reaction (HER).

For the same Pd NP loading, N-G is found to be the best support to achieve the smallest

overpotential (difference between the applied and theoretical potentials) and the highest

catalytic activity, as shown in Figure 1a. The overpotential at a current density of 10 mA cm−2

(η10) on Pd/N-G is 160 mV smaller than that on Pd/rGO. Tafel analysis derived from the

polarizaiton curves shows that Pd/N-G has a Tafel slope of 101 mV decade−1, indicating the

rate determining step of HER on Pd/N-G is the Volmer step (H3O++e−+ * ⇄H*+H2O, where

* denotes the active site). The activity difference of four composites should be ascribed to the

NP size and size distribution of Pd NPs anchored onto these supports. NP size is well-

documented to strongly affect the catalytic activity/selectivity because more surface active sites

are exposed as size decreases. N-G is thus reasoned

to gain the smallest Pd NP size and best size

distribution during the radiolytic synthesis, which

should be correlated to the positive role of doped N

atoms in stabilising the formed NPs.

Given the positive role of doped N atoms, we

further prepare N-G supported with four loadings of

Pd NPs to explore the potential threshold in

maintaining the Pd NP size. Figure 1b presents the

polarization curves of N-G loaded with 1.3~5.2 wt.

% Pd NPs and the benchmark Pt/C catalyst. The

best performance of Pt/C accords well with the

literature. In contrast, the η10 and Tafel slope are

found to be the smallest for 2.6 wt. % Pd/N-G,

indicating its highest HER catalytic activity. The

decreased activity of 3.9 and 5.2 wt. % Pd/N-G

should be attributed to the severe aggregation of Pd

NPs, leading to lower atom efficiency. Therefore, in

order to achieve a desirable NP size and size

distribution, the NP loading shall be carefully

controlled.

Figure 1. Polarization curves of Pd NPs

supported on four graphene-based supports

(a) and Pd NPs supported on N-G with four

loadings (b) in 0.5 M H2SO4.



53

Poster 4: Role of Electronic Energy Loss of the Ion Beam in the

Modification of Graphene Oxide Film

Chetna Tyagi1,2, A. Tripathi2 and D. K. Avasthi3

1Dalton Cumbrian Facility, The University of Manchester, Cumbria, UK, 2Inter-University Accelerator Centre, New Delhi, India,

3Amity Institute of Nanotechnology, Amity University, Noida, India.

Ion beam irradiation is a clean method to produce desired modifications in materials in a

controlled manner [1]. The present work shows the modifications induced in graphene oxide

film under swift heavy ion irradiation with different electronic energy loss. Graphene oxide

films were irradiated with Gold ion beam having energy 120 MeV with fluences varying from

3×1010 ions/cm2 to 1×1013 ions/cm2. X-ray diffraction and spectroscopic techniques indicated

some annealing effect induced by ion beam at lower fluences of irradiation while signature of

carbyne could be seen in Raman spectroscopy at higher fluence (Figure 1). Similarly, Carbon

beam of energy 80 MeV with relatively low electronic energy loss was used to irradiate the

graphene oxide films with different fluences. Different characterization techniques showed the

creation of defects by ion beam in the films. Theoretical simulations showed the local lattice

temperature raised in the films when irradiated with ion beams having different energy loss. It

could be seen that ion beam having high electronic energy loss could raise the temperature of

the film above its annealing and melting temperature, resulting in two competing phenomena:

annealing and amorphization. Also, the estimated radius of the ion track (core and halo region)

formed by Gold ions irradiation was calculated experimentally and compared with the

theoretical values obtained by simulation.

(a) (b)

Figure 1. (a) Plot showing the intensity of in-situ X-ray diffraction peak of pristine and

irradiated sample and (b) Raman spectra of irradiated sample with different fluence. Magnified

part is showing the origin of carbyne peak at high fluences.

Reference

1. GK Mehta, (1997) Swift heavy ions in Materials Science – emerging possibilities, Vacuum, 48, 957-

959.



54

Poster 6: Radiation Induced Polymerization of Nanostructured Conducting

Polymers

T. Bahry1 and S. Remita2

1Laboratoire de Chimie Physique, LCP, UMR 8000, CNRS, Université Paris-Sud 11, Bât. 349, Campus d’Orsay, 15 Avenue Jean Perrin, Orsay Cedex 91405, France

2Département Chimie Vivant Santé, Conservatoire National des Arts et Métiers, CNAM, 292 rue Saint-Martin, Paris Cedex 75141, France.

Conducting polymers (CPs) have gained vast attraction due to their unique optical and

electrical properties [1]. Thanks to these prominent and extraordinary properties, CPs have

been used in several fields and integrated in many applications [2]. Tremendous efforts have

been made to develop and upgrade the synthesis methodologies of CPs [3]. Apart from

traditional methods of polymers synthesis, ionizing radiation induced polymerization by -rays

without using oxidizing agents appears to be alternative and easy way to produce conducting

polymers. Indeed, our group has developed a new methodology based on radiation chemistry

to polymerize some of those conducting polymers (CPs) in aqueous solutions [4, 5]. Recently,

we extended this methodology to the synthesis of CPs in organic solvent [6]. In this context,

we succeeded in the oxidative polymerization of different classes of thiophene derivatives

monomers dissolved in dichloromethane by means of gamma-radiolysis (Figure 1). The

spectroscopic analysis and microscopic observations manifest that the radio-synthesized

polymers in dichloromethane are characterized by interesting optical and electrical.

Reference(s)

1. A. J. Heeger, J. Phys. Chem. 2001, 105 (36), 8476-8491.

2. R. Balint, et al., Acta Biomater. 2014, 10(6), 2341-53.

3. X. T. Zhang, et al., J. Phys. Chem. 2006, (110), 1158−1165.

4. Y. Lattach, et al., Radiat. Phys. Chem. 2013, (82), 44-53.

5. Z. P. Cui, et al., Langmuir. 2014, (30), 14086−14094.

6. T. Bahry et al., New J. Chem. 2018, 42 (11), 8704-8716.1.

Figure 6. PEDOT, P3HT and P3TAA synthesized by gamma radiolysis in

dichloromethane



55

Poster 8: Effect of Surface Deformation on Stress Corrosion Crack

Initiation in Austenitic Stainless Steels in PWR Primary Water

Litao Chang, M. Grace Burke, Fabio Scenini

Materials Performance Center, The University of Manchester, Manchester, UK M13 9PL

Austenitic stainless steels are widely used in the nuclear power plants due to their good general

corrosion resistance to the high temperature aqueous environment. However, they can suffer

from environmentally-assisted degradation problems, such as stress corrosion cracking (SCC),

during the long-term exposure to the environment. Numerous researches indicate that cold-

work, induced either intentionally or incidentally, is necessary for SCC in austenitic stainless

steels in PWR primary water. In the present study, the effect of the machining-induced surface

deformation on SCC initiation of austenitic stainless steels in PWR primary water has been

investigated through accelerated slow strain rate tensile tests and microstructural

characterization. The results showed that machining always introduced a deformation layer to

the steels. This layer is characterized by an ultrafine-grained outer layer and a highly deformed

inner layer consisted of twins and dislocations. SSRT test results showed that machining

significantly reduced the SCC initiation susceptibility of the cold-worked material as a reduced

number of cracks were identified in the machined surface compared to the polished surface.

The results also indicated that a low temperature heat treatment could further increase the SCC

initiation resistance of the machined surface because of the recovery which happened with the

ultrafine-grain. The associated mechanisms and possible implications of the results have been

discussed.

Reference(s)

1. Chang et al., Stress corrosion crack initiation in machined type 316L austenitic stainless steel in

simulated pressurized water reactor primary water, Corr. Sci. (2018) 138, 54-65

2. Chang et al., Effect of machining on stress corrosion crack initiation in warm-forged type 304L

stainless steel in high temperature water, Acta Mater. (2019)165, 203-214

3. Chang et al., Understanding the effect of surface finish on stress corrosion crack initiation in warm-

forged stainless steel 304L in high-temperature water, Scripta Mater. (2019) 164, 1-5



56

Poster 10: Method of Assessing the Radiation Tolerance of Commercial

Strippable Coatings

A. Jenkins1, L. Ostle1, T. Donoclift2, R. Edge2, T. Unsworth2, K. Warren2

1 Sellafield Ltd., Seascale, Cumbria. UK

2Dalton Cumbrian Facility, University of Manchester, Moor Row, Whitehaven, Cumbria. UK

There are a plethora of commercially available strippable coating products, designed for

contamination control and decontamination purposes. Sellafield Ltd. has sought for a number

of these to be subjected to a predefined series of analyses pre and post irradiation to observe

any degradation of the product. Irradiation of the coatings to doses of 500kGy was separately

carried out by cobalt-60 and ion-beam to mimic plutonium alpha particles by Dalton Cumbrian

Facility. This dose threshold was deemed sufficient to allow for wastes to be packaged and

reach the respective disposal point.

A series of analyses were carried out and comparisons made of the pre and post irradiation.

The analyses included; direct observations for physical colour changes and deformities,

scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR),

Raman spectroscopy, Gas Chromatography – Mass Spectroscopy (GC-MS) and energy-

dispersive X-ray spectroscopy (EDS).

An illustration of how these coating systems degrade will be given alongside more anecdotal

perspective of how more easily obtained gamma irradiation can be used to infer alpha

degradation of organic species.



57

Poster 12: The Degradation of Lithium Acetate under Gamma Irradiation

in Degassed and Hydrogenated Conditions

C. McBride1, A. Baidak1, S. Heath2 and R. Wain3

1Dalton Cumbrian Facility, The University of Manchester, Westlakes Science Park, Moor Row, Cumbria, CA24 3HA;

2Dalton Nuclear Institute, The University of Manchester, Pariser Building, Sackville Street, Manchester, M13 9PL;

3Rolls Royce PLC, Jubilee House, 4 St Christopher’s Way, Pride Park, Derby, DE24 8JY.

Zinc injection is a commonly practised technique in the nuclear industry for the mitigation of

primary water stress corrosion cracking and the reduction of adsorbed radiation doses. Zinc,

most commonly in the form of zinc acetate, is injected into the primary cooling loop of the

PWR to undergo substitution mechanisms in the metal that makes up the primary cooling loop,

and while the mechanism of the zinc cation under the harsh conditions of the PWR is well

understood, the fate of the acetate counter ion is not documented in literature.

Concerns have been raised about the effect of products formed from the radiolysis of acetate

on the life time of ion exchange columns in the PWR and the effect of acetate on the partitioning

of carbon-14. In this poster the radiolytic degradation of the acetate ion in both degassed and

hydrogenated conditions is analysed and discussed in order to better understand its fate under

PWR conditions.



58

Poster 14: Understanding the Effect of Microstructure Strain and Cold

Work on Intergranular Corrosion of AGR Fuel Cladding

S. Thornley1, D. Engelberg1, S. Walters2

1The University of Manchester, School of Materials, Sackville Street Campus, Manchester, M13 9PL; 2NNL Building D5, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB.

Fuel pins in Advanced Gas Cooled Reactors (AGRs) are made form 20%Cr/25%Ni-Nb

stabilised austenitic stainless steel. Due to elevated temperatures and neutron irradiation a small

proportion of the fuel pins may become sensitised whilst in service. These materials can then

be susceptible to Intergranular Corrosion (IGC) during interim pond storage. The spent fuel

remains active for the duration of interim storage. Water exposed to gamma radiation can

undergo radiolysis producing a range of reactive species, which can promote corrosion in steel

components. The aim of this project is to understand the role that Cold Work (CW) and

microstructure strain play in promoting IGC during interim storage in water-cooled ponds.

Double Loop – Electrochemical Petentiokinetic Reactivation (DL-EPR) is an

electrochemically technique, which was used in this work to assess the Degree of Sensitisation

(DOS). Solution annealing (1150 °C for 0.5 hrs) followed by sensitisation treatments (600 °C

for 168/336 hours) was used to produced sensitised microstructures. The samples, prior to

thermal treatments, were in two conditions: As Received (AR) and Cold rolled to ~30 % CW.

Gamma irradiation exposure, using a 60Co planar irradiator, was used to test the IGC

susceptibility of AR sensitised samples. Further corrosion test took place using c-ring samples,

without irradiation, exposed to chloride environments. The tests were: submersion in 10 wt %

FeCl3 for 5 days at room temperature (test 1). Atmospheric Corrosion tests with droplets of 1

M/ 4 M MgCl2 at 60 °C for 7 days (tests 2/3).

DL-EPR testing revealed that the DOS increased with introduction of CW and when the

sensitisation time was increased from 168 to 336 hours. The susceptibility of the sensitised

microstructure to IGC was also confirmed on the gamma irradiated samples where significant

corrosion, surrounding the grain boundaries, was observed. In test 1 and 2 corrosion product

was observed to have formed during testing however no localised corrosion was observed.

However, test 3 showed a significant amount of pitting but no cracking.



59

Poster 16: Gamma Irradiation and Hydrogen Production of Potassium

Activated Metakaolin Geopolymers

T.A. Mubasher1,2, A. Potts1 and L. Leay1

1 The University of Manchester, Dalton Cumbrian Facility, Westlakes Science Park, Whitehaven, Cumbria. CA24 3HA.

2 Centre for Innovative Nuclear Decommissioning (CINDe) – National Nuclear Laboratory (NNL), Workington, Cumbria, CA14 3YQ.

Geopolymers are cementitious materials produced through the condensation reaction between

a precursor (aluminosilicate) and alkali activator solution. Once this condensation reaction is

complete these materials exhibit a complex interconnected pore structure which contains water.

This study aims to investigate the effect of curing time on radiolytic hydrogen production from

potential formulations being explored by the nuclear industry for intermediate level waste

(ILW) immobilisation.

Potassium based metakaolin

geopolymers were mixed and cured for

1 year. The samples were crushed and

powdered to 300 – 500 μm, Sub samples

were dried overnight at 40 °C and

120 °C under vacuum. The samples

were dried at 40 °C and 120 °C before

being irradiated, to observe the effect of

loosely and tightly bound water. For

hydrogen analysis, the powdered

samples (1 g each) were placed in crimp

cap vials, degassed under argon and then

gamma irradiated. The head space was

then analysed using gas chromatography.

Hydrogen analysis of geopolymer samples

cured for 1 year (Figure 1), indicate that samples dried at 40 °C produces a larger quantity of

hydrogen on irradiation compared with samples dried at 120 °C or non-dried samples. The

typical primary yield G (H2) value for water is 0.45 x10-7 mol/J (Eliot & Bartels, 2009),

whereas the samples investigated in this study achieved values from 0.13 to 1.16 x10-7 mol/J

(Table 1). Oxygen depletion was observed in the head space of dried samples, by gas

chromatogram. Additional work is underway to assess how the concentration of dissolved

species we expect to find in the pore water affects radiolytic hydrogen production. Initial results

from experiments using simulants of the pore water indicate that more concentrated simulant

results in greater hydrogen production.

Table 1: G values of F13 1 year cured samples calculated using the mass of the whole system

and not just the water.

System G(H2) Value (x10-7) mol/J

Not Dried 0.31

Dried at 40 °C 1.16

Dried at 120 °C 0.13

Figure 7: Hydrogen analysis of a 1 year cured

geopolymer



60

Poster 18: Poly(Acrylic Acid) Radicals Recombination in Aqueous

Solutions

M. Matusiak, S. Kadlubowski, P. Ulanski

Institute of Applied Radiation Chemistry, Lodz University of Technology, Lodz, Poland

Polyelectrolytes constitute a broad class of polymers including the most important biopolymers

(nucleic acids, proteins, many polysaccharides), as well as synthetic polymers. Presence of

charge along the chain makes many aspects of physical chemistry of polyelectrolytes more

complex than for neutral macromolecules [1,2]. This is also true for reaction kinetics. This

work is intended as a step forward in exploration of radical reactions in weak polyelectrolyte

solutions. The main model is poly(acrylic acid) - PAA. Poly(acrylic acid) plays a key role in

discussion of the properties and behaviour of water-soluble synthetic polymers because it is

the simplest common synthetic polycarboxylic acid. Previous studies on PAA radical reactions

have focused on identification of radicals and indication of their transformation mechanisms

[3,4], overall radical lifetimes [5,6] and on the application of intramolecular crosslinking for

synthesizing PAA nanogels [4,6]. The kinetics of radical recombination has not been studied

in detail so far. In the presented preliminary research we have focused on the strong effect of

charge density on the lifetime of PAA radicals and at radical recombination at pH 2.

Recombination of poly(acrylic acid) radicals is strongly influenced by its dissociation degree

and thus by pH. At pH 2 recombination is fast, in an more alkaline environment, reactions are

much slower. Kinetics and mechanism of the recombination depend on the average number of

radicals generated on each chain. A transition in kinetics is observed between intermolecular

and intramolecular recombination.

The results, beside providing basic information about polymer radicals, their lifetime, kinetics

both in intra- and intermolecular reaction modes in aqueous polymer solutions, may also be

relevant to some extent for radical reactions in biopolymers, most of them being

polyelectrolytes. Moreover, it provides information about PAA which can be later used to

design radiation-synthesized polymer nanoparticles used for controlled drug-, gene- and

radioisotope delivery systems.

This work has been supported by the National Science Centre, Poland, project no.

2017/27/N/ST4/02536.

References

1. Görlich, W., & Schnabel, W. (1973) Untersuchungen über den einfluß der ladungsdichte auf die

gegenseitige desaktivierung von polyion‑makroradikalen Makromol.Chem. 164, 225-235.

2. Behar, D., & Rabani, J. (1988) Pulsed radiolysis of poly (styrenesulfonate) in aqueous solutions J.

Phys. Chem., 92, 5288-5292.

3. Ulanski, P., Bothe, E., Hildenbrand, K., Rosiak, J. M., & von Sonntag, C. (1995) Radiolysis of

poly (acrylic acid) in aqueous solution Radiat. Phys. Chem., 46, 909-912.

4. Matusiak, M., Kadlubowski, S., & Ulanski, P. (2018) Radiation-induced synthesis of poly (acrylic

acid) nanogels. Radiat. Phys. Chem., 142, 125-129.

5. Ulanski, P., Rosiak, J. M., Bothe, E., Hildenbrand, K., & von Sonntag, C. (1997) The influence of

repulsive electrostatic forces on the lifetimes of poly (acrylic acid) radicals in aqueous solution

Nukleonika, 42, 425-436.

6. Kadlubowski, S., Grobelny, J., Olejniczak, W., Cichomski, M., & Ulanski, P. (2003) Pulses of fast

electrons as a tool to synthesize poly (acrylic acid) nanogels. Intramolecular cross-linking of linear

polymer chains in additive-free aqueous solution Macromolecules, 36, 2484-2492.



61

Poster 20: Preventing the Development of Antibiotic Resistance in

Wastewater Matrices by High Energy Irradiation

R. Homlok1, L. Szabó1, K. Kovács1, T. Tóth1, E. Takács1, Cs. Mohácsi-Farkas2, L.

Wojnárovits1

1Institute for Energy Security and Environmental Safety, Centre for Energy Research, Hungarian Academy of Sciences, Konkoly-Thege Miklós út 29-33, H-1121 Budapest, Hungary;

2Department of Microbiology and Biotechnology, Faculty of Food Science, Szent István University,

Somlói út 14-16, H-1118 Budapest, Hungary.

Nowadays, one of the most important challenges of environmental protection is preservation

and improvement of water quality. A wide range of pollutants are released into our natural

waters all over the world. Among several pharmaceutical contaminants, antibiotics in particular

have a very harmful effect on the environmental microbiota. As a result, antibiotic residues

may concentrate in plants and animals; integrate into the living organisms and contribute to the

spread of antibiotic resistance, which represents a serious issue worldwide [1].

During development of antibiotic resistance, several genetic processes occur in bacteria that

can confer the microbes different protecting mechanisms to overcome their previous sensitivity

against the antibiotic. As a result, resistant or even multi-resistant microorganisms have been

created. Microbes are able to pass these resistant genes to related or even non-related species

by horizontal gene-transfer that permits the rapid spread of resistance involving also pathogen

microorganisms [2]. This is a major threat to public health.

In our laboratory, we have studied the applicability of electron beam irradiation in eliminating

the antimicrobial activity of several groups of antibiotics [3-5]. We have also placed special

emphasis to find out whether any effect can be observed on the population dynamics of a mixed

resistant and sensitive microbial population during advanced oxidation of antibiotics at the sub-

inhibitory level [5]. It appeared from these studies that the technology needs to be carefully

optimized and there is still much to be done in this field. As a continuation of our previous

studies, we take further steps to understand more complex systems by applying microbiological

assays on model wastewater matrices. The presentation will give an insight into our recent

advances.

Reference(s)

[1] Baquero, F., Martínez, J.L., Cantón, R. (2008) Antibiotics and antibiotic resistance in water

environments. Current Opinion in Biotechnology 19, 260-265.

[2] Wright, G.D. (2010) Antibiotic resistance in the environment: a link to the clinic?, Current Opinion

in Microbiology 13 589–594.

[3] Szabó, L., Szabó, J., Illés, E., Kovács, A., Belák, Á., Mohácsi-Farkas, Cs., Takács, E., Wojnárovits, L. (2017) Electron beam treatment for tackling the escalating problems of antibiotic resistance:

eliminating the antimicrobial activity of wastewater matrices originating from erythromycin. Chemical

Engineering Journal 321, 314-324.

[4] Sági, Gy., Bezsenyi, A., Kovács, K., Klátyik, Sz., Darvas, B., Székács, A., Mohácsi-Farkas, Cs.,

Takács, E., Wojnárovits, L. (2018) Radiolysis of sulfonamide antibiotics in aqueous solution:

Degradation efficiency and assessment of antibacterial activity, toxicity and biodegradability of

products. Science of the Total Environment 622-623, 1009-1015.

[5] Szabó, L., Steinhardt, M., Homlok, R., Kovács, K., Illés, E., Kiskó, G., Belák, Á., Mohácsi-Farkas,

Cs., Takács, E., Wojnárovits, L. A microbiological assay for assessing the applicability of advanced

oxidation processes for eliminating the sublethal effects of antibiotics on selection of resistant bacteria.

Environmental Science and Technology Letters 4, 251-255.



62

Poster 22: Kinetic Studies on Dextran and Dextran Methacrylate in

Aqueous Solutions

K. J. Szafulera, R. A. Wach and P. Ulanski

Institute of Applied Radiation Chemistry, Lodz University of Technology

High interest in the use of ionizing radiation for the processing of polymers is mainly because this

technique is a very efficient and clean tool, especially for modification of polysaccharides.

These polymers, due to their natural origin, non-toxic and biodegradable character, are constantly

finding new applications in various important fields, including medicine [1]. Dextran helps in curing

vascular thrombosis, reduces inflammatory response and promotes vascularization, hence it is

a promising candidate for soft tissue regeneration [2]. Our main goal is to synthesize a dextran

derivative, dextran methacrylate (Dex-MA), having substituents capable of covalent crosslinking and

subsequently further development of conditions suitable for the formation of macroscopic hydrogels by

radiation technique, which is an attractive approach to produce new class of wound dressing

in the future [3]. For better understanding of crosslinking or/and degradation processes occurring upon

irradiation of aqueous solutions of Dex-MA and the role of particular products of water radiolysis

in these processes, pulse radiolysis study of dextran and Dex-MA was performed.

A series of Dex-MA has been synthesized, yielding dextran methacrylate of moderate degree

of substitution (DS), up to 0.65, allowing the product to retain its solubility in water. A wide range

of initial dextran’s molecular weight (Mw) was employed (6, 25, 70 and 500 kDa). Pulse radiolysis

studies of dextrans and Dex-MA in aqueous solutions indicate that radicals on this polymer are formed

by reactions of both hydroxyl radicals and hydrated electrons. In order to study the reactivity of ·OH

and 𝑒𝑎𝑞− with respect to the -MA substituent, methacrylic acid (MAA) was also employed as a model

compound. To determine the rate constants of ·OH attack, competitive kinetics with SCN- scavenger

was used. It can be concluded that the reactions of the ·OH with dextran and Dex-MA are fast, their rate

constants are high, in the order of 108 [dm3/mol∙s] for all studied DS and Mw. A slight increase in the

rate of this reaction was observed along with an increase in DS, which indicates that the methacrylic

group reacts with the ·OH faster than with the basic sugar unit. The rate constant of MAA with ·OH is

2.2∙1010 [dm3/mol∙s], which confirmed this conclusion. In order to determine the rate constant of 𝑒𝑎𝑞− a

direct absorbance measurement of decay at 720 nm was used. As expected, the reaction rate constant

of 𝑒𝑎𝑞− with dextran is low, 106 [dm3/mol∙s]. Introduction of the methacrylic substituent into dextran

structure causes the increase of this constant by two orders of magnitude. The increase in the rate

constant is due to the high reactivity of the hydrated electron in relation to the double bonds and the

carbonyl group present in methacrylic moieties (MAA reacts with 𝑒𝑎𝑞− with rate constant of 5.6∙109

[dm3/mol∙s]). Therefore, the obtained results show that the formation of radicals on the main chain of

dextran corresponds primarily to the reaction of hydroxyl radical, while the formation of radicals on

the methacrylic substituent is due to both ·OH and 𝑒𝑎𝑞− .

References

1. The Radiation of Chemistry of Polysaccharides, International Atomic Energy Agency, IAEA, Vienna (2016)

2. S. Dumitriu, Polysaccharides: structural diversity and functional versatility, CRC Press, Boca Raton FL

(2005)

3. K. Szafulera et al., Radiat. Phys. Chem. (2018), 142, 115–120

Acknowledgments

Authors acknowledge the National Science Centre, Poland (2017/25/N/ST4/01814) for financial support.



63

Poster 24: Phosphate Buffer Influence on Tyrosyl Radicals Formation

Sebastian Sowinski, Slawomir Kadlubowski, Piotr Ulanski

Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology

Exposition of biomolecules to oxidative stress (i.e. by reaction with water radiolysis products)

can lead to changes in their structure that impair their functionality. On the other hand,

introduced changes may possibly involve formation of protein-protein crosslinks, that can be

utilized in synthesis of nanoparticles with wide range of biomedical uses. Radiation-induced

crosslinking with formation of nanostructures has been demonstrated for globular proteins such

as papain [1] and bovine serum albumin [2]. Postulated mechanism of this process involves

formation of phenoxyl-type tyrosyl radicals (TyrO•) which after isomerization and subsequent

recombination form covalent bonds, but some aspects, such as influence of the buffer on the

process remain unclear. Better understanding of the radiation chemistry in this system is

therefore important to introduce changes in protein structure in more controlled way.

Low-molecular-weight model (tripeptide H-Gly-Tyr-Gly-OH) was used to partially simulate

behavior of tyrosine in more complex protein systems. Pulse radiolysis with

spectrophotometric detection was used to determine kinetic aspects of TyrO• formation in

phosphate buffer solutions. Influence of phosphate buffer on the reaction rate constants

involved in phenoxyl radicals formation, as well as possible reaction with phosphate derived

radicals were investigated. Experimentally obtained reaction rate constants were double-

checked using simple probabilistic simulations in Kinetiscope software package.

References

1. Varca G.H.C., Perossi G.G., Grasselli M., Lugão A.B. (2014) Radiat Phys Chem, 105, 48-52.

2. Queiroz R.G., Varca G.H.C., Kadłubowski S., Ulański P., Lugão A.B. (2016) Int J Biol Macromol.,

85, 82-91.



64

Poster 26: Partial Molar Volume of the Hydrated Electron and a Comment

on Its Vertical Detachment Energy

Ireneusz Janik, Alexandra Lisovskaya and David M. Bartels

Notre Dame Radiation Laboratory, Notre Dame University, Notre Dame, Indiana, USA.

The partial molar volume of the hydrated electron was investigated with pulse radiolysis and

transient absorption2 by measuring pressure-dependence of the equilibrium constant for e-aq + NH4+

H + NH3 . At 2 kbar pressure the equilibrium constant decreases relative to 1 bar by only

6%. Using tabulated molar volumes for ammonia and ammonium, we have the result V(e-aq) –

V(H) = 11.3 cm3/mol at 25oC, confirming that V(e-aq) is positive and even larger than the

hydrophobic H atom. Assuming the molar volume of H atom is somewhat less than that of H2, we

estimate V(e-aq ) = 26±6 cm3/mol. The positive molar volume is consistent with an electron that

exists largely in a small solvent void, ruling out a recent controversial model of Larsen, Glover and

Schwartz3 (LGS) that suggests a non-cavity structure with negative molar volume. It is suggested

that no one-electron pseudopotential model of the hydrated electron is likely to capture all of the

dynamical properties of this species that depend on details of the wavefunction. A full ab initio MD

approach may be necessary.

A recent paper of Luckhaus, et al1 has presented

photoelectron data and analysis of eleven liquid microjet experiments with various excitation

wavelengths from 3.6 to 5.8 eV to extract a

“genuine” distribution of vertical electron binding

energies for the hydrated electron (Figure 1). The

analysis involves correction of the individual

photoelectron energy distributions at each

wavelength for scattering losses in the liquid before

escape into the vacuum. Surprisingly the

distribution reported is bimodal, resembling two overlapping Gaussians with centers at 3.5 and 4.5

eV. We find the bimodal distribution highly

implausible, as it represents a gross violation of

linear response for the hydrated electron ground

state energy. Rather, we identify a flaw in the

calculation of scattering losses that leads to the

bimodal distribution. The “bottom of the

conduction band” in liquid water has been taken to

be Vo = -1.0 eV relative to the vacuum. In the

scattering model used, electrons with kinetic energies below 1.0 eV never escape from the liquid

microjet. This assumption is shown to be

inconsistent with the data being fitted, and a more likely number is Vo = -0.1 ± 0.1 eV.

References

1. Luckhaus, D.; Yamamoto, Y. I.; Suzuki, T.; Signorell, R. Genuine Binding Energy of the

Hydrated Electron. Science Advances 2017, 3 (4).

2. Janik, I.; Lisovskaya, A.; Bartels, D. M. Partial Molar Volume of the Hydrated Electron.

Journal of Physical Chemistry Letters 2019, 10 (9), 2220-2226.

3. Larsen, R. E.; Glover, W. J.; Schwartz, B. J. Does the Hydrated Electron Occupy a Cavity?

Science 2010, 329 (5987), 65-69.

Figure 1. “Genuine” electron Binding

Energy (eBE(g)) distribution reported by

Luckhaus, et al.1 The bimodal

distribution (asterisks) with average of

3.7eV can be decomposed into a pair of

Gaussian functions centered at ca. 3.5

and 4.5 eV.



65

Poster 28: Oxygen Effects on Antioxidant Protection of Lymphoid Cells

against Free Radicals by a Range of Dietary Carotenoids

R. Edge1, F. Boehm2 and T.G. Truscott3

1Dalton Cumbrian Facility, The University of Manchester, Westlakes Science Park, Moor Row, Cumbria, UK;

2Photobiology Research, IHZ, Berlin, Germany; 3School of Physical Science (Chemistry), Keele University, Staffordshire, UK.

Carotenoids are natural pigments, being constituents of a wide variety of fruits and vegetables,

though chlorophyll often masks their presence. Believed to act as dietary antioxidants, having

been shown to quench both singlet oxygen and a range of free radicals, carotenoids are of

interest for their health benefits. While carotenoids are consumed in significant quantities from

normal diets, in recent years, they are also consumed in large quantities via food supplements.

This may well be based on claims that they offer major health benefits but there are also

counter-claims that they can be damaging to human health.

We have shown previously that dietary lycopene, the red carotenoid pigment in tomatoes,

protects against human lymphoid cell membrane damage from free radicals produced by γ-

radiation and that this protection is dramatically reduced when the oxygen concentration is

increased [1].

In this work we study a wider range of dietary carotenoids, showing protection of human

lymphoid cells from membrane damage caused by free radicals produced by γ-radiation. Blood

was taken from volunteers who had supplemented their diet with large doses of a specific

carotenoid for 2 weeks or had minimized carotenoid-rich fruit and vegetables in their diet.

Radical-induced cell membrane destruction was shown by cell staining with eosin.

All carotenoids studied imparted protective effects and the carotenoid protective effect was

reduced as oxygen concentration increased, as previously seen for lycopene. In fact, the oxygen

effect was observed to be most pronounced for lycopene, where there was almost no protection

under 100% oxygen, down from 5-fold protection at 21% oxygen and, an extremely high, 50-

fold, protection in the absence of oxygen. Studies with β-carotene and the xanthophylls,

astaxanthin, zeaxanthin and lutein, have shown a reduced, but still significant, oxygen effect.

Gamma radiation cellular studies have also been undertaken with the addition of superoxide

dismutase, showing that the effect is not due to reactions of the superoxide radical.

Additionally, a series of non-cellular gamma radiolysis studies in simple solutions, as well as

cell protection studies against nitrogen dioxide radical, generated photolytically, have also been

carried out to help elucidate the molecular mechanisms for the observed oxygen effect.

The remarkable reduction in protection by carotenoids, particularly lycopene, against gamma

radiation at high oxygen concentrations could, perhaps, be exploited to enhance radiation

procedures for therapy.

References

2. Boehm, F., Edge, R., Truscott, T.G. and Witt, C. (2016) A dramatic effect of oxygen on protection

of human cells against γ-radiation by lycopene. FEBS Lett., 590, 1086-1093.



66

Poster 30: Drastic Changes in the Surface Reactivity of UO2-Based Spent

Nuclear Fuel upon Exposure to Radiolytic Oxidants – How Will This

Influence the Safety Assessment of Deep Geological Repositories for Spent

Nuclear Fuel?

A. C. Maier and M. Jonsson*

Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden

Several countries plan to store their spent nuclear fuel in deep geological repositories for

extremely long time periods (>100000 years). This calls for rather extreme safety assessments

accounting for a multitude of possible scenarios. A commonly used scenario is groundwater

intrusion into a fuel canister after 1000 years. Since UO2 (the matrix of the most commonly

occurring spent nuclear fuel) has very low solubility in the reducing groundwater expected to

be found at the depth of a typical repository, the main process driving the fuel matrix

dissolution and the subsequent release of fission products and heavier actinides is radiolysis of

groundwater. The oxidants produced upon radiolysis of groundwater are capable of oxidizing

U(IV) to the considerably more soluble U(VI) and thereby solubilize the fuel matrix. Previous

studies have shown that the most important oxidant in these systems is H2O2. To assess the

long-term leaching behavior of UO2, the oxidative dissolution of UO2 pellets was studied at

high H2O2 exposures (expressed as amount of oxidant consumed per surface area) ranging from

0.3 mol m-2 to 1.4 mol m-2. The results indicate that the dissolution yield (amount of dissolved

uranium per consumed H2O2) at high H2O2 exposures is significantly lower compared to

previous studies of both pellets and powders and decreases for each H2O2 addition for a given

pellet. This implies a change in redox reactivity by a factor of three to four, which is attributed

to irreversible alteration of the pellet surface. Surface characterization after the exposure to

H2O2, by SEM, XRD and Raman spectroscopy show, that the surface of all pellets is

significantly oxidized.

The same type of study was also performed on Gd-doped UO2 (Gd is used as a burnable neutron

absorber in commercial nuclear fuel) revealing similar trends at different doping levels. The

results of the studies performed on pure UO2-pellets and Gd-doped UO2-pellets are discussed

in combination with relatively recent findings on the reactivity of UO2-powder (exposed to

H2O2 as well as ionizing radiation) as a function of stoichiometry. Finally, the overall impact

of these findings on the safety assessment for deep geological repositories for spent nuclear

fuel is discussed.



67

Poster 32: Chemical Dosimetry of Femtosecond Electron Bunches Provided

by Laser-Plasma Acceleration

Gérard Baldacchino1, Houda Kacem1, Pierre Forestier-Colleoni1, Jean Daniel Ahui1, Tiberio

Ceccotti1, Sandrine Dobosz Dufrénoy1

1LIDYL, UMR9222 CEA CNRS, Université Paris-Saclay, 91191 Gif-sur-Yvette, France.

The radiobiological effects of the recent protocol in radiotherapy named FLASH seem to be in

relation with the dose rate effect of µs electron pulses. Actually, it spares healthy tissues and

damages tumor cells in a radiotherapy utilization, which improves the treatment prognostic

compared to conventional radiotherapy [1]. This effect could be enhanced by using a higher

dose rate provided by femtosecond electron pulses generated by laser-plasma accelerator. In

this framework, we have studied the chemical effect associated to electron pulses as short as a

few femtoseconds which are provided by high intensity laser (1018 W/cm2) in interaction with

a gas mixture of 99%H2+1%N2.. In these conditions, we expect to produce ultimate dose rates

of electrons in the range of the TGy/s (ie: 1012 Gy.s-1). Their energy belongs to the range 20-

100 MeV. In order to evaluate the dose rate effect in liquid water by chemical fashion, the

determination of radiolytic yields (G-values) of radicals and molecules such as hydrated

electron, hydroxyl radical and hydrogen

peroxide is mandatory. As G-value is the limit

value at dose = 0 of C/d, we first determined

the doses d by simulation using GEANT4

program and electron counting at every shot.

Then, we have used fluorescence spectroscopy

for measuring sensitively the concentrations C

of the above-mentioned species. Then the

scavenging method using Resazurin and

Ampliflu Red as described in ref [2] gives G-

values determination as depicted in figure 1.

The comparison with G-values obtained under

-rays were performed. We will show that

electrons bunches provided by the UHI100

installation at Saclay [3] have produced a small

dose rate effect because hydrated electron and hydroxyl radical have G-values 0.026 and 0.023

µmol.J-1 respectively. H2O2 one seems increased. It will be discussed as well. As these yields

account for the species escaped from recombination in the spurs, molecules could be then

favored because they are the result of radical-radical reactions.

References

1. Favaudon, V., Fouillade, C., Vozenin, M.C. (2015) Ultra-high dose-rate, "flash" irradiation

minimizes the side effects of radiotherapy. Cancer Radiothérapie. 19, 526-531.

2. Baldacchino, G., Brun, E., Denden, I., Bouhadoun, S., Roux, R., Khodja, H., Sicard-Roselli, C.

(2019) Importance of radiolytic reactions during high‑LET irradiation modalities: LET effect, role of

O2 and radiosensitization by nanoparticles. 10, 1-21.

3. Maitrallain, A., Audet, T.L., Dobosz Dufrénoy, S., Chancé, A., Maynard, G., Lee, P., Mosnier, A.,

Schwindling, J., Delferrière, O., Delerue N, Specka, A., Monot, P., Cros, B. (2018) Transport and

analysis of electron beams from a laser wakefield accelerator in the 100 MeV energy range with a

dedicated magnetic line NIMA: Accelerators, Spectrometers, Detectors and Associated Equipment.

908,159-166.

Figure 1. Resorufin (RN) concentration as a

function of the dose delivered by electron bunches

@ UHI100 installation. Slope at d=0 gives the G-

value of OH, here under N2O bubbling.



68

Poster 34: Studying Nascent Proton-Driven Radiation Chemistry in H2O in

Real Time Using Laser-Based Sources

M. Coughlan1*, N. Breslin1, M. Yeung1

, H. Donnelly1, C. Arthur1, L.Senje2, M. Taylor1, G.

Nersisyan1, D. Jung1, M. Zepf2 and B. Dromey1

1Department of Physics and Astronomy, Queen’s University Belfast, Belfast, United Kingdom 2Helmholtz-Institut Jena, D-07743 Jena, Germany

*[email protected]

Understanding the effects of ion interactions in condensed matter has been a focus of research

for decades. While many of these studies focus on the longer term effects such as cell death or

material integrity, typically this is performed using relatively long (>100 ps) proton pulses from

radiofrequency accelerators in conjunction with chemical scavenging techniques [1].

As protons traverse a material, they generate tracks of ionisation that evolve rapidly on

femtosecond timescales. Recently, measurements of few-picosecond pulses of laser driven

protons have been performed via observation of transient opacity induced in SiO2 with sub-

picosecond resolution [2]. Here we present results showing a dramatic difference in the

solvation of electrons generated due to the interaction of relativistic electrons/X-rays and

protons in liquid water. The role of ionisation tracks and subsequent formation of nanoscale

cavities in water on the extended recovery time is discussed.

References

[1] G. Baldacchino, Radiation Physics and Chemistry, 77, 1218-1223 (2008). [2] B.Dromey, et al. Nature Communications, 7, 10642

mailto:*[email protected]



69

WEDNESDAY 11TH SEPTEMBER 16:00-17:00

POSTER SESSION 2

(ODD NUMBERS)



70

Poster 1: Femtosecond Resolution for Picosecond Radiolysis Using Electron

Pump-Repump-Probe Spectroscopy

S.A. Denisov and M. Mostafavi

Laboratory of chemical physics UMR8000/CNRS, Université Paris-Saclay, Orsay, France

For decades electron picosecond radiolysis

set-ups remain workhorses of fast time-

resolved radical chemistry despite presence

of subpicosecond electron accelerators.

The list of systems where later could be

applicable is rather short despite high

efficient doses, due to the effect of the

group velocity mismatch of the electron

and the light in the sample what limits

samples length to sub-mm paths [1].

Meanwhile the concentration (manifested

in optical density) of produced radicals is a

crucial issue for radiolysis studies in sub-

and picosecond regimes.

In our work, the newly implemented

technique of 3 pulse electron pump (5 ps) –

optical repump by laser (110 fs) and probe by

with light (150 fs) on the ELYSE platform

(Université Paris-Saclay, Orsay) will be

discussed in details. This technique

reinforces existing platform by opening new

research fields earlier inaccessible due to

time-resolution issues of electron

accelerator.

The electron solvation mechanism in water and other solvents will be revisited. Along with

that, perspective experiments accessible to three pulse spectroscopy will be discussed,

revealing research fields, e.g., dissociative electron attachment in liquids previously directly

unreachable for existing time-resolved radiolysis experimental set-ups limitations [2-3].

Reference(s) 1. Yang, J.; Kan, K.; Kondoh, T.; Yoshida, Y.; Tanimura, K. and Urakawa, J. Femtosecond pulse

radiolysis and femtosecond electron diffraction. Nucl Inst Methods Phys Res A 2011, 637, 24–33

2. Ma, J.; Wang, F.; Denisov. S.A.; Adhikary, A. and Mostafavi, M. Reactivity of prehydrated

electrons toward nucleobases and nucleotides in aqueous solution. Sci Adv 2017, 3, e1701669

3. Ma, J.; Kumar, A.; Muroya, Y.; Yamashita, S.; Sakurai, T.; Denisov, S.A.; Sevilla, M.D.;

Adhikary, A.; Seki, S. and Mostafavi, M. Observation of dissociative quasi-free electron attachment

to nucleoside via excited anion radical in solution. Nat Commun. 2019, 10, 102.

Figure 1. Optical density evolution of

solvated electron signal @620 nm,

@1200 nm excited by repump (780 nm) pulse

after passage of 5 ps electron pulse.

Relaxation of the transient signals occurs after

less than 270 fs, corresponding to the

transition from p state to the s-like state.



71

Poster 3: Molecular Simulations of the Oxidative Radiolysis of two Inverse

Peptides: Methionine Valine and Valine Methionine

P. Archirel1, Ch. Houée-Lévin1 and J. L. Marignier1

1Laboratoire de Chimie Physique, Université Paris-Sud, 91405 Orsay, France

Oxidative radiolysis of the peptides has been performed at the Elyse facility of the LCP. The

two peptides undergo very different processes, as can be seen on the absorption spectra

recorded at different times and concentrations. We have also performed molecular simulations,

in order to interpret these spectra. Our method associates Monte-Carlo sampling of the nuclear

configurations, DFT and TDDFT calculations of the electronic structure and PCM simulation

of the solvent [1,2]. The results enable a fine understanding of the two species:

1. Met-Val displays a main band at 390 nm and no concentration effect. This is due to the

H atom uptake leaving a neutral radical Met-Val (-H) stabilized by a (2c-3e) SN bond.

This species is very stable and undergoes no bimolecular reaction with neutrals.

2. Val-Met displays a complex spectrum with at least three species, see figure 1, left, and

a striking concentration effect. The three species are plausibly a Val-Met (-H) radical

at high energy (285 nm), the Val-Met+ cation, stabilized by a (2c-3e) SO bond at middle

energy (367 nm) and a (Val-Met)2+ dimer cation, stabilized by a (2c-3e) SS bond, at

lower energy (540 nm), see figure 1, right. This last species can be formed either by

direct oxidation of neutral dimers present in solution, and by bimolecular dimerization

of cation monomers. This last species has not been simulated, but can be inferred from

simulations of the Met2+ cation [3].

Figure 1 Oxidative radiolysis of Val-Met: measured (left) and simulated spectra (right) of a

neutral radical (black curve), the cation (red curve) and the dimer (green curve)

References

1. Gaussian 09 RevD01 Gaussian Inc. Wallingford CT, 2013

2. Wang, F. Horne, G. Pernot, P. Archirel, P. and Mostafavi, M. J. Phys. Chem. B 122 (2018), 7134-

7142

3. Archirel, P. Bergès J. and Houée-Lévin, Ch. J. Phys. Chem. B 120 (2016), 9875-9886



72

Poster 5: Comprehensive Model for X-ray Induced Damage in Protein

Crystallography

D. Close, W. Bernhard

Acquisition of X-ray crystallographic data is always accompanied by structural degradation

due to the absorption of energy. The application of high fluency X-ray sources to large

biomolecules has increased the importance of finding ways to curtail the onset of X-ray induced

damage. A significant effort has been underway with the aim of identifying strategies for

protecting protein structure. A comprehensive model is presented that has the potential of

explaining, both qualitatively and quantitatively, structural changes induced in crystalline

protein at ~100 K. The first step is to consider the qualitative question, what are the radiation

induced intermediates and expected end products? The aim of this presentation is to assist in

optimizing these strategies through a fundamental understanding of radiation physics and

chemistry with additional insight provided by theoretical calculations performed on the many

schemes presented.



73

Poster 7: Electron Irradiation Treatment of Nanodiamonds

C. Laube1, J.Zhou2, A.Kahnt1, W. Knolle1, Bernd Abel1

1Leibniz Institut of Surface Engineering, Leipzig, Germany, 2Helmholtz Centre of Environmental Research UFZ, Leipzig, Germany

Nanodiamonds (NDs) offer great potential on multiple fields of research such as medical and

sensory application. Herein, the tailoring of the ND surface functionalities and color center

formation inside the diamond lattice can be regarded as key factors for the suitability of the

NDs for these applications. Especially the efficient formation of NV color centers lies within

the focus of modern application. In this work, we demonstrated the application of electron

irradiation as a powerful tool for tailoring these properties. In particular we demonstrated the

efficient surface modification of NDs based on a pulse radiolysis approach of ND suspension.

As a test model we established the efficient surface chlorination of NDs by electron irradiation

of ND suspension in halogenated solvents.1 Furthermore, electron irradiation was applied for

the effective formation of lattice vacancies, in order to enhance the formation of NV centers.

Within a comprehensive study we demonstrated that the formation and the resulting properties

of NV centers can be controlled via irradiation treatments, parameters and the surface

functionalities.2

Reference(s)

1. J. Zhou, C. Laube, W. Knolle, S. Naumov, A. Prager, F.-D. Kopinke and B. Abel, Diamond

and Related Materials, 2018, 82, 150-159.

2. C. Laube, T. Oeckinghaus, J. Lehnert, J. Griebel, W. Knolle, A. Denisenko, A. Kahnt, J.

Meijer, J. Wrachtrup and B. Abel, Nanoscale, 2019, 11, 1770-1783.

Figure 8 Shematic illustration of the preparation approaches

for the nanodiamond surface chlorination (above)

and NV center formation (below).



74

Poster 9: Hydrogen Production by Steel Anoxic Corrosion under Gamma

Irradiation

Lina Giannakandropoulou1, Benoît Marcillaud1, Stéphane Poirier1, Hortense Desjonqueres1,

Charles Wittebroodt2, Gérard Baldacchino3

1Institute for Radiological Protection and Nuclear Safety (IRSN), PSN-RES/SCA/LECEV, BP68, Gif-sur-Yvette, France;

2Institute for Radiological Protection and Nuclear Safety (IRSN), PSE-ENV/SEDRE/LETIS, BP17,

Fontenay-aux-Roses; 3LIDYL, Université Paris-Saclay, Atomic Energy and Alternative Energy Commission (CEA), Gif-sur-

Yvette, France.

In the framework of the storage of High Level nuclear Wastes (HLW), ANDRA (National

Radioactive Waste Management Agency in France) is planning their isolation in deep

geological disposals. Such a disposal repository concept is based on a multi-barrier system

including large amount of metallic elements such as stainless steel primary canister or carbon

steel casing for HLW disposal gallery. After a period of several decades, anoxic corrosion of

these metal elements will cause a release of hydrogen gas [1]. Simultaneously, the radiation

emitted by radioactive wastes would lead to the radiolysis of the water present in the

geological formation. This process may lead to a production of additional hydrogen gas and

other redox species likely to modify the redox conditions of the aqueous medium as well as the

corrosion processes of the steel and therefore, the hydrogen production [2].

This study aims at assessing the influence of

-irradiation on H2-production rate through the

anoxic corrosion of carbon steel process. Two

experimental stainless steel cells are placed in an

irradiation chamber IRMA (IRSN facility)

where they are exposed to -radiation of 60Co

(50 Gy/h) for twelve days. The first cell contains

carbon steel coupons (15 gr) immerged in pure

deaerated water (100 mL) and the second cell

contains only pure deaerated water. An He-gas

flows through these cells to a gas chromatograph

for measuring the evolution of H2-production

before, during and after irradiation. Post-mortem analysis are then performed on liquid and

solid phases. Metallic samples is structurally characterized for the identification of the formed

corrosion products upon their surfaces with XRD, μRaman spectroscopy and SEM-EDS

microscopy. The loss of mass of the coupons is measured in order to estimate the carbon steel

corrosion rate. Liquid samples are analysed for their Eh and pH values. In parallel, UV-Vis

spectroscopy is used to determine the concentration of both dissolved Fe2+ and Fe3+ ions. A

fluorescence method is used to assess the hydrogen peroxide (H2O2) concentration. Finally,

kinetics are compared with those obtained by simulations using Chemsimul software. First

results on H2-production show that our experiment allows us to distinguish in time the

contributions of the solid phase (corrosion) and the radiolytic processes in the bulk of the liquid

phase. These results are also supported by simulation in the homogeneous liquid phase but

needs an heterogeneous approach modelling the interface processes.

References

1. Smart, N.R., Rance, A.P., Werme, L.O., 2008.The effect of radiation on the anaerobic corrosion of steel. Journal of Nuclear Materials 379, 97-104.

2. Pimblott, S. M. and LaVerne J. A., 1992. Molecular product formation in the electron radiolysis of

water. Radiation Research 129(3): 265-271.

Figure 1 : µRaman spectra indicates the presence of

magnetite at 675 nm.



75

Poster 11: Radiolytic Degradation of an Extractant for Actinides, HONTA

— a Comparative Study of Direct and Indirect Radiolysis Processes

Y. Kumagai1, T. Toigawa1, S. Yamashita2, T. Matsumura1

1Japan Atomic Energy Agency, Ibaraki, Japan; 2The University of Tokyo, Ibaraki Japan.

Ionizing radiation induces degradation of organic molecules. This action of ionizing radiation

needs to be incorporated in designing and safety evaluation of solvent extraction processes for

separation of radioactive elements [1]. A reliable estimation of the effect of radiolysis requires

understanding of the degradation mechanism as well as basic data regarding the extractant

degradation and its radiolytic products. This study focuses on a promising extractant for

separation of actinides from lanthanides, hexaoctyl- nitrilotriacetamide (HONTA) [2]. We have

investigated the radiolysis of HONTA by LC-MS/MS analysis of radiolytic products of

HONTA and by UV-visible spectroscopy of its radical transient using pulse radiolysis

technique. In these experiments, radiolysis of neat HONTA and that of HONTA in dodecane

solvent are compared in order to understand the degradation mechanism.

The samples for the product analysis were irradiated by 60Co γ-ray (60Co irradiation facility,

QST Takasaki) and were analysed by an LC-MS/MS system (Shimadzu, LCMS-8300). The

mass-chromatograms for the irradiated neat HONTA and 10 mM HONTA in dodecane are

shown in Figure 1. We found 43 products, in total, of HONTA degradation. Among them, 14

products were commonly observed in the radiolysis of neat

HONTA and the dodecane solution, 20 products were only

found in the neat HONTA, and 9 products are characteristic

for the dodecane solution. Indeed, 14 out of 43 products are

common in these two, although the initial radiolysis

processes in these samples must be different, i.e. direct

ionization and excitation of HONTA occur under neat

condition, whereas the degradation of HONTA is due to

reactions of radicals from dodecane radiolysis in the

solution. This result suggests that the direct and the indirect

processes have a common reaction pathway. Therefore, we

measured absorption spectra of transient species by using a

nano-second pulse radiolysis system. (LINAC facility, Univ.

Tokyo) in order to investigate the reaction pathways. The

measured spectra had similar shapes in this time domain

regardless of the HONTA concentrations. This indicates that

there is a common transient both in the radiolysis of neat

HONTA and of dodecane solution of HONTA. Consistently

with the product analysis, the result of the pulse radiolysis

experiment indicates a common reaction pathway between

the direct and the indirect radiolysis.

Acknowledgment: This work was supported by JSPS KAKENHI Grant Numbers JP18K05001.

References

3. Mincher, B.J., Modolo, G., and Mezyk, S.P. (2009) Review Article: The effects of radiation

chemistry on solvent extraction 3: A review of actinide and lanthanide extraction. Solvent Extr. Ion

Exch., 27, 579-606

4. Sasaki, Y., Tsubata, Y., Kitatsuji, Y., and Morita, Y. (2013) Novel Soft-Hard Donor Ligand,

NTAamid, for Mutual Separation of Trivalent Actinoids and Lnthanoids, Chem. Lett., 42, 91-92.

Figure 1 Mass chromatograms of the irradiated samples (130 kGy); (a) neat HONTA, (b) 10mM HONTA in n-dodecane.



76

Poster 13: New Explanation for Radiosensitization by Gold Nanoparticles:

Chemical Effect

V. Shcherbakov, N. Chen, S.A. Denisov and M. Mostafavi

Laboratory of chemical physics/CNRS_Université Paris-Saclay, Orsay, France

Gold nanoparticles (AuNPs) are presented to be an efficient radiosensitizer for cancer

radiotherapy [1]. During the last decades, many important works were performed to show the

radiosensitization by different particles for different tumors. But still, there is no explanation

for AuNPs radiosensitizating effect. Physical explanation based on Compton, photoelectric and

Auger effects cannot explain the radiosensitizing effect in solutions, because the nanomolar

concentration of AuNPs does not change dose deposition in the solution. Therefore, other ideas

were proposed such as overproduction of ∙OH radicals [2] due to special properties of

interfacial water around nanoparticles and

scavenging of excess electrons [3, 4] what

increases the concentration of ∙OH radicals

around the nanoparticles.

In the present work, we show by pulse radiolysis

that AuNPs react neither with reducing radicals:

pre-solvated electron, solvated electron (e-s), ∙H

nor oxidizing one ∙OH, what is manifested in the

same e-s formation yields (5 ps) in the presence

and absence of AuNPs; and the same decay of e-

s in microsecond time range [5]. In addition,

unchanged e-s decay in the presence of AuNPs

showed that overproduction of OH radicals is not

occurring. In the present work we perform a new

approach to show the effect of AuNPs in

radiosensitization.

As biological systems are complex, therefore here we used simple organic models to conclude

on the mechanism of the radiosensitizing effect of AuNPs. By gamma radiolysis, we show that

in an irradiated solution of 2-propanol in the presence of AuNPs the radiolytic yield of acetone

– the product of oxidation of alcohol, is higher than in the absence of nanoparticles (Figure 1).

Such studies were carried out for other organic compounds in order to confirm the effect of

gold nanoparticles on this radiolytic enhancement. In our work we will propose the detailed

mechanism and discuss how it can explain radiosentisization by AuNPs.

References:

1. Wang, H., Mu, X., He, H., & Zhang, X. D. (2018). Cancer radiosensitizers. Trends in pharmacological sciences, 39(1), 24-48.

2. Gilles, M., Brun, E., & Sicard-Roselli, C. (2018). Quantification of hydroxyl radicals and solvated

electrons produced by irradiated gold nanoparticles suggests a crucial role of interfacial water.

Journal of colloid and interface science, 525, 31-38.

3. Ghandi, K., Wang, F., Landry, C., & Mostafavi, M. (2018). Naked Gold Nanoparticles and hot

Electrons in Water. Scientific reports, 8(1), 7258.

4. Ghandi, K., Findlater, A. D., Mahimwalla, Z., MacNeil, C. S., Awoonor-Williams, E., Zahariev, F.,

& Gordon, M. S. (2015). Ultra-fast electron capture by electrosterically-stabilized gold nanoparticles.

Nanoscale, 7(27), 11545-11551.

5. Shcherbakov, V., Denisov, S.A., Ghandi, K., Mostafavi, M., Pulse radiolysis study of AuNPs

solutions. (to be published)

Figure 1. The dose dependent of acetone

formation in 2-propanol solution in the

presence and absence of AuNPs.



77

Poster 15: Study on the Dose Enhancement in Water by Activation of

Clusters of Nanoparticles of High-Z Materials with a 6 MeV True Varian

Linac

B. Villagomez-Bernabe1,2 and F. Currell1,2

1Chemistry Department, The University of Manchester, Manchester, UK; 2Dalton Cumbrian Facility, Cumbria, UK.

During the last decade, different nanomaterials have been implemented for biomedical

applications in Nanomedicine, such as imaging agents [1] and drug delivery agents [2].

Furthermore, different types of nanoparticles are being studied as radiosensitizers in cancer

treatment [3,4]. This work aims to calculate through Monte Carlo simulations the dose

enhancement in water for three different nanoparticles composition such as gold, silver and

gadolinium in order to compare their effectiveness based only on the physical interactions

between gamma irradiation and the nanoparticles, i.e. without taking into account the influence

of the radicals formed by each type of nanoparticles. Nevertheless, as far as the authors are

aware, such a computational study involving clustering of nanoparticles has not been published

to date.

The present work is divided into two stages, during the first

stage, the random positions of the nanoparticles inside a

water sphere were calculated using Wolfram Mathematica.

This mimics the sub-cellular distribution of nanoparticles

commonly observed using microscopy. Those coordinates

were used to create a parameter file in TOPAS [5] with the

information of the position, material and size of the

nanoparticles. The geometry set-up created with the

parameter file is shown in Fig. 1, where a cluster of

nanoparticles was loaded into TOPAS for posterior

irradiation with a 6 MeV True Varian Linac obtained from

the International Atomic Energy Agency website. Then, a

phase space file placed around the cluster of the

nanoparticles was used to record all electrons going out from the cluster. The final stage

involves the releasing of all particles from the space phase file previously recorded during stage

1 into a water phantom in order to measure the dose deposited in radial bins around the cluster.

The Geant4-DNA physics list was used to track low energy electrons down to 10 eV. The radial

dose distribution for each type of nanoparticle were compared against each other and plotted

for better visualization.

Reference(s)

1. Rippel R.A. and Seifalian A.M. (2011) Gold Revolution -Gold nanoparticles for modern medicine

and surgery. Journal of Nanoscience Nanotechnology, 11, 7340-48.

2. Ghosh P., Hang G., De M., Chae K.K. and Rotello V.M. (2008) Gold nanoparticles in delivery

applications. Advanced Drugs Delivery Reviews, 60, 1307-15.

3. McMahon S.J. et al (2011) Nanodosimetric effects of gold nanoparticles in megavoltage radiation

therapy. Radiotherapy Oncology, 100, 412-416.

4. Taupin F. et al. (2015) Gadolinium nanoparticles and contrast agents as radiation sensitizers.

Physics in Medicine and Biology, 60, 4449-64.

5. Perl, J. et al. (2012) TOPAS: an innovative proton Monte Carlo platform for research and clinical

applications. Med Phys., 39, 6818-37.

Fig. 1. cluster of

nanoparticles randomly

distributed.



78

Poster 17: Effects of Additives on Radiation-Induced DNA Damage: From

the Viewpoints of Free Radical Scavenging and Chemical Repair

H. Yu1, K. Fujii2, A. Yokoya2 and S. Yamashita1

1The University of Tokyo, Tokyo, JAPAN; 2Natinal Institutes for Quantum and Radiological Science and Technology (QST), Chiba, JAPAN.

1. INTRODUCTION

Radiation-induced DNA damage can be reduced by small amount of additives like

antioxidants. Such additives can repair unstable oxidative damage intermediately produced in

DNA by reductive reaction (chemical repair) as well as remove oxidizing radicals such as •OH

produced as a result of water radiolysis (radical scavenging). Low concentration of additives

cannot remove all of the oxidizing radicals, therefore, the chemical repair process must be more

important. We investigated the effect of additives against radiation damage to DNA. For this

purpose, pulse radiolysis experiments were conducted to observe the additive’s reactions not

only with radicals produced by water radiolysis but also with a tentatively oxidized DNA model

compound. In this study, dGMP (deoxyguanosine monophosphate, purchased from Thermo

Fisher Scientific) was used as model compound of DNA moiety. In addition, a gel

electrophoresis was conducted to evaluate the yield of stable DNA damage.

2. EXPERIMENT

Pulse radiolysis was conducted at the LINAC facility of the University of Tokyo. Details of

the apparatus are described in elsewhere[1].

Plasmid DNA, pUC18, was extracted from cultured Escherichia coli (JM109) and purified

by dialysis to remove organic impurities. Dilute aqueous solutions and films of the plasmid

DNA were irradiated with X-rays and stable DNA damage were detected and quantified by an

agarose gel electrophoresis method[2].

As additives, we used Tris-EDTA (TE), which are the solutes of pH buffer often used for

DNA storage, and typical antioxidants such as ascorbic acid (purchased from Fujifilm Wako)

and flavonoid rutin (received from Toyo Sugar or purchased from Fujifilm Wako).

3. RESULTS & DISCUSSION

Transient absorption spectra of the scavenging reaction of rutin toward •OH had at least three

peaks, which were attributed to the products of OH adduct, hydrogen atom subtraction, and

electron subtraction. The ratio of the peak intensities was not constant, indicating an

intramolecular transformaton following the scavenging reaction. On the other hand, the reacion

of rutin toward tentatively oxidized dGMP radical showed a clear peak in the spectra, which

was the same as the peak corresponding to hydrogen abstraction observed for the scavenging

reaction as described above.

Purification by dialysis resulted in higher yields of stable DNA damage induction, indicating

that non-negligible impurities could protect the DNA from radiation damage. The damage

yields in dilute aqueous solutions were much higher than those in hydrated plasmid DNA films.

This suggests that additional damage is produced due to the indireact actions of radicals

produced by watar radiolysis.

References

[1] K. Hata, et al., J. Radiat. Res., 52, 15 (2011).

[2] A. Yokoya et. Al., J. Am. Chem. Soc. 124, 8859 (2002).



79

Poster 19: Solvation Effects on Dissociative Electron Attachment to

Thymine

Jorge Kohanoff 1 and Bin Gu1,2

1Atomistic Simulation Centre, Queen’s University Belfast, Belfast BT7 1NN, U.K.; 2Department of Physics, Nanjing University of Information Science and Technology, Nanjing 210044,

China.

Ionizing radiation can excite the cellular medium to produce secondary electrons that can

subsequently cause damage to DNA. The damage is believed to occur via dissociative electron

attachment (DEA). In DEA, the electron is captured by a molecule in a resonant antibonding

state and a transient negative ion is formed. If this ion survives against electron

autodetachment, then bonds within the molecule may dissociate as energy is transferred from

the electronic degrees of freedom into vibrational modes of the molecule.

We present a model for studying the effect that transferring kinetic energy into the vibrational

modes of a molecule has on a DNA nucleobase. To simulate the effect of the additional energy

that would be introduced due to a DEA event, we vertically attached an excess electron to the

system and introduced additional vibrational energy to the N−H bond. We can tune the

vibrational energy of a molecular bond by increasing the velocities and hence the kinetic

energies of the constituent atoms.

We found that the breaking of an N−H bond and releasing a hydrogen atom, which in the gas

phase requires 1.67 eV, is strongly affected by the aqueous environment. When there is a

hydrogen bond between the N−H of the nucleobase and a surrounding water molecule, there is

no guarantee that the bond breaks even when up to 5 eV of additional energy is inserted into

the bond. The reason for this is that this hydrogen bond rapidly channels the kinetic energy

away from the N−H, into the surrounding water molecules, and back into the nucleobase.

Fig. 2 The reaction channels of the (Transient negative ion)TNI of thymine with low energy

dissociative electron attachment (DEA) in aqueous solvent, with the relevant potential energy surface

(PES) shown as functions of the N-H distance. Reference

McAllister, M., Kazemigazestane, N., Henry, L. T., Gu, B., Fabrikant, I., Tribello, G. A., & Kohanoff,

J. (2019). Solvation Effects on Dissociative Electron Attachment to Thymine. The Journal of Physical

Chemistry B, 123(7), 1537–1544.



80

Poster 21: Effect of Supports on Metal-Nanoparticle Catalysts: The

Radiolytic H2 Evolution Reaction

Gifty Sara Rolly,1 Ronen Bar-Ziv 2 and Tomer Zidki 1

1Department of Chemical Sciences, Ariel University, Ariel, Israel; 2Department of Chemistry, Nuclear Research Centre Negev, Beer-Sheva, Israel.

The performance of the silica-supported M0 nanoparticles as catalysts for water reduction was

studied using the strongly-reducing ·C(CH3)2OH radicals at acidic and alkaline media. It was

found that supporting metal nanoparticles (M0-NPs, M = Pt, Au, Ag) on an "inert" support such

as SiO2 alters the catalytic properties of the metals. This effect depends both on the nature of

M and on the concentration of the composite nanoparticles. At low nanocomposite

concentration: for M = Au nearly no effect is observed; for M = Ag the support decreases the

catalytic reduction of water, and for M = Pt the support initiates the catalytic process. At high

nanocomposite concentration: for M = Au the reactivity is considerably lower, and for M = Ag

or Pt, no catalysis is observed. Furthermore, for M = Ag or Pt H2 reduces the ·C(CH3)2OH

radicals. Changing the medium from alkaline to acidic pH did not affect these trends.

Therefore, we conclude that the metal oxide support affects the M0-NPs redox properties.

Below is the proposed mechanism pathways for the production of H2 and the deactivation of

H2 evolution.



81

Poster 23: Radiation-Induced Redox Chemistry of Californium-249

David S. Meeker1,2, Gregory P. Horne1, Travis S. Grimes1, Peter R. Zalupski1, James F.

Wishart3, Stephen P. Mezyk4, and Thomas E. Albrecht-Schmitt2

1 Idaho National Laboratory, Center for Radiation Chemistry Research, Idaho Falls, ID, P.O. Box

1625, 83415, USA 2 Florida State University, Department of Chemistry and Biochemistry, Tallahassee, FL, 32306-4390,

USA. 3 Brookhaven National Laboratory, Department of Chemistry, Upton, New York, 11973, USA.

4`California State University Long Beach, Department of Chemistry and Biochemistry, Long Beach,

CA 90804, USA.

A complete understanding of californium chemistry necessitates knowledge of its

radiation-induced redox behavior, owing to its inherent nuclear instability propagating self-

radiolysis. Only a handful of studies have investigated californium radiation chemistry, due to

lack of element availability and difficulty associated with handling highly radioactive material.

To date, reaction rate coefficients (k) have only been experimentally determined for the

reduction of Cf(III) by the hydrated electron (e¯aq, k > 3 × 109 M–1 s–1) from water radiolysis,

and subsequent decay of the corresponding transient Cf(II) (k = (7 ± 1) × 105 s–1)[1]. However,

there are a number of other important transient radiolysis products radiolytically generated in

solutions pertinent to californium manipulations, e.g., the hydrogen atom (H•, Eo = 2.31 V),

hydroxyl radical (•OH, Eo = –2.73 V), and nitrate radical (•NO3, Eo = –2.3 – –2.6 V). These

species are more than capable of influencing the redox behavior of californium, and have been

shown to do so with a number of actinides, e.g., neptunium and americium.[1,1,1] Here we

present the results from the first time-resolved picosecond pulsed electron radiolysis

measurements for californium-249. The reaction rate coefficients were determined by direct

decay of the observed species or via competition kinetics. For the reductive reactions of Cf(III)

with the e¯aq and H• transients, the reaction rate coefficients were measured to be (7.11 ± 0.18)

× 1010 and (2.61 ± 0.54) × 108 M−1 s−1, respectively, while studies for the oxidation of Cf(III)

by the •NO3 and •OH species yielded (2.0 ± 0.5) × 108 and (7.2 ± 0.6) × 108 M−1 s−1, respectively

References

1. Sullivan, J.; Morss, L.; Schmidt, K.; Mulac, W.; Gordon, S. Pulse Radiolysis Studies of

Californium (III) in Aqueous Perchlorate Solution. Evidence for the Preparation of Californium

(II). Inorg. Chem., 1983, 22, 2339.

2. Horne, G. P.; Grimes, T. S.; Mincher, B. J.; Mezyk, S. P. Re-evaluation of Neptunium-Nitric

Acid Chemistry by Multi-Scale Modelling. Journal of Physical Chemistry B, 2016, 120 (49), 12643–12649.

3. Grimes, T. S.; Horne, G. P.; Dares, C. J.; Pimblott, S. M.; Mezyk, S. P.; Mincher, B. J. Kinetics

of the Autoreduction of Hexavalent Americium in Aqueous Nitric Acid. Inorganic Chemistry,

2017, 56 (14), 8295-8301.

4. Horne, G. P.; Grimes, T. S.; Bauer, W. F.; Dares, C. J.; Pimblott, S. M.; Mezyk, S. P.; Mincher,

B. J., Effect of Ionizing Radiation on the Redox Chemistry of Penta- and Hexavalent

Americium. Inorganic Chemistry, submitted 28th March 2019.



82

Poster 25: Reduction of Cobaoxime-Based Complexes: Mechanisms,

Products and Implications

A. Kahnt1, E. Hofmeister2, T. Ullrich3, K. Hanus1 and M. von Delius2

1Leibniz Institute of Surface Engineering (IOM), Leipzig, Germany. 2Institute of Organic Chemistry and Advanced Materials, University of Ulm, Ulm, Germany.

3Chair of Physical Chemistry I, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.

Cobaltoxime based complexes have attracted strong interest in the past and present. Decades

ago the focus was set on alkyl and alkenyl cobaloximes as vitamin B12 model system1. Later,

new interest arose regarding this class of compounds owing to the fact that Co(dmgBF2)2

catalyses the reduction of protons in acidic solutions.2 In this regard, cobaloxime complexes

are considered as candidates for the “Holy Grail” in the field of renewable energy - that is the

formation of renewable fuel from solar energy, to potentially meet the future energy demands

without the use of fossil fuel. Several cobaltoxime based systems containing organic and/or

inorganic chromophores3 for light harvesting have been coordinated to the cobalt centre of

cobaloxime complexes and have been successfully tested for the photocatalytic reduction of

water.

But, plenty of this systems prompt to a up to hours lasting induction period for the

photocatalytic reduction of water.4 Surprisingly, the reasons for such a phenomenon remain

largely unknown4 and comes hardly in line with the usual

proposed reaction mechanisms postulating a reduction

from a CoIII to a CoI species. Our past work5,6 related to

photocatalytic water reduction triggered our interest in the

understanding of this mechanism. In line with the latter,

we conducted a full fledge spectroscopic and kinetic

investigation of the reduction of mono-nuclear Co-

complexes by pulse radiolysis assays, however, we found

solid evidence that a final product of the reduction process

was a dinuclear complex.6 From this finding we derived

the implication that for an efficient induction period free

photo-catalysts least two Co-centres like in the CoIII double salt presented in figure 1 are

required. For these new and very efficient class of proton reduction photo-catalysts detailed

investigations of the reduction mechanism by pulse radiolysis were conducted in order to

establish the mechanism behind the found quite efficient proton reduction.7

Reference(s)

1. Prince R.H., Segal, M.G. (1974) Nature, 249, 246-247.

2. Connolly P., Espensson J.H. (1986) Inorg. Chem., 25, 2684-2688.

3. Artero V., Fontecave M. (2013) Chem. Soc. Rev., 42, 2338-2356.

4. Du P., Eisenberg R. (2012) Energy Environ. Sci., 5, 6012-6021.

5. Peuntinger K., Lazarides T., Daphnomili D., Charalambidis G., Landrou G., Kahnt A., Sabatini R.,

McCamant D., Gryko D.T., Coutsolelos A., Guldi D. M. (2013) J. Phys. Chem. C, 117, 1647-1655.

6. Kahnt A., Peuntinger K., Dammann C., Drewello T., Hermann R., Naumov S., Abel B., Guldi D.

M. (2014) J. Phys. Chem. A, 118, 4382-4391.

7. Hofmeister, E., Ullrich, T., Petermann L., Hanus, K., Rau, S., Kahnt, A., von Delius, M. (2019) Angew. Chem. Int. Ed., under preparation.

Figure1. New generation of

Co-double salts as core

structure for novel proton

reduction photo-catalysts [7].



83

Poster 27: γ-Radiolysis of Thermal Transition Phases in Boehmite

Patricia L. Huestis1 and Jay A. LaVerne1

1Department of Physics and Notre Dame Radiation Laboratory, University of Notre Dame, Notre

Dame, IN, USA.

Over 200 million liters of high level waste (HLW) reside in the Hanford Waste Tanks. These

tanks contain legacy waste from the Cold War era and are chemically complex due to high

nitrate concentrations, high pH, and large radiation fields. Boehmite (γ-AlOOH) is a large

component of the solid waste located within the tanks and is especially problematic due to its

longer than predicted dissolution times. Boehmite has a layered structure which consists of an

Al-O lattice hydrogen bonded together via bridging OH groups. The mechanism responsible

for hydrogen production in boehmite is still not well understood.

Boehmite was heated to various temperatures along its dehydration pathway to assess the

structural differences and their effect on the radiolysis of boehmite. Structural changes were

investigated using powder X-Ray Diffraction (pXRD), Raman spectroscopy, nitrogen

adsoption, and Scanning Electron Microscopy (SEM). Radiolytic effects were assessed using

Gas Chromatography (GC) and Electron Paramagnetic Resonance (EPR). Different sizes of

materials were used to investigate the size dependence on the thermal degradation and its effect

on the creation of radiolytic products by gamma rays.

The yield of H2 with respect to energy deposited into the material/water system is nearly

constant for both sizes of material heated below 300°C with the smaller material having a

slightly higher yield. The larger material, when preheated further to 400°C, shows a dramatic

increase in H2 production. Larger material preheated to 550°C as well as smaller material

preheated to both 400°C and 550°C shows a yield consistent with alumina, indicating complete

or near complete dehydration. Initial production of trapped hydrogen radicals within the larger

material in conjunction with the yield for the sample preheated to 400°C suggest that the

hydrogen production mechanism is likely an abstraction reaction by H atoms with surface water

as opposed to a bimolecular combination reaction.



84

Poster 29: Key Role of the Oxidized Citrate Free Radical in the Nucleation

Mechanism of the Metal Nanoparticles Turkevich Synthesis

Sarah Al Gharib,1,2, Jean-Louis Marignier,1 Adnan Naja,2 Abdel Karim El Omar,2 Sophie Le

Caer,3 Mehran Mostafavi,1 and Jacqueline Belloni1.

1 Laboratoire de Chimie-Physique/ELYSE, UMR 8000 CNRS/UPS, Université Paris Sud, Université Paris-Saclay, Bât. 349, F-91405 Orsay Cedex, France.

2 Laboratoire Physique et Modélisation, Université Libanaise, Tripoli, Lebanon. 3 Laboratoire LIONS, DSM/IRAMIS/NIMBE UMR 3685 CNRS/CEA/Saclay, Université Paris-Saclay,

Bât. 546, F-91191 Gif-sur-Yvette, Cedex, France.

The step-by-step mechanism of the citrate oxidation, of the silver ion reduction [1] [2] into

atoms, and of the nucleation of nanoparticles by the Turkevich method [3] are deduced from

the gamma- and pulse radiolysis yields of dicarboxy acetone (DCA), H2 and CO2 and of silver

ion reduction. Our results demonstrate that the stronger reductant is not citrate (Cit) but the

oxidized radical Cit(-H)•. The formation yields of DCA and CO2 confirm the decarboxylation

process during the Cit(-H)• oxidation. In pulse radiolysis of solutions of sodium citrate and

silver perchlorate, the transient spectra [4] and the kinetics are observed from 20 ps to 800 ms.

In particular, the successive H abstraction from citrate by OH• radicals, then the one-electron

transfer from the citrate radicals Cit(-H)• to silver ions initiating the simultaneous nucleation

and growth of the reduced silver oligomers are observed. The knowledge of the nuclearity-

dependent kinetics and thermodynamics of silver atoms, oligomers and nanoparticles in

solution is used to bracket the standard reduction potentials of the first (≥ 0.4 VNHE) [2] and the

second one-electron transfers from citrate (≤ - 1.2 VNHE) [2]. During the Turkevich synthesis,

the Cit(-H)• radical was shown to be released in the bulk solution from the citrate oxidation by

Ag+ adsorbed on the walls (Figure 1), or directly by the trivalent AuIII ions present in the bulk,

respectively. Then the strong Cit(-H)• reductant alone is able, as in radiolysis, to overcome the

thermodynamic barrier of the very negative potential for the reduction of the free monovalent

ions into atoms that is required to initiate the nucleation and growth (Figure1). The reduction

potentials values of citrate and Cit(-H)• also explain part of the antioxidant properties of citrate.

Reference(s)

1. Marignier, J.L;. Belloni, J. ; Delcourt, M.O. ; Chevalier, J.P Nature, 1985, 317, 344-345.

2. Belloni J., Mostafavi, M., Radiation Chemistry of Clusters and nanocolloids. In Studies in

physical and theoretical chemistry, Radiation Chemistry:, Jonah, C.D. ; Rao, M. (eds), Elsevier,

2001, 87, 411-452.

3. Turkevich, J.; Stevenson, P.C.; Hillier, J. Disc. Faraday Soc. 1951, 55-75.

4. Simic, M.; Neta, P.; Hayon, E. J. Phys. Chem. 1969, 73, 4214-4219.



85

Poster 31: The Radiation Chemistry of Aqueous PVP Solutions Exposed to

Pulsed E-beam Irradiation: Experiments and Numerical Simulations

C. Dispenza1, M. A. Sabatino1, B. Dahlgren2, M. Jonsson2

1Department of Engineering, University of Palermo, Italy. 2Department of Chemistry, KTH Royal Institute of Technology, Sweden.

Nanogels have recently raised considerable interest in the biomedical field, due to their diverse

applications in tissue engineering, regenerative medicine and drug delivery.

One-pot radiation-induced synthesis of nanogels from dilute aqueous polymer solutions is one

example of a process that has been successfully carried out using electron accelerators equipped

with scanning horn and a conveyor belt. In dilute aqueous systems the radiation energy is

mainly absorbed by water. Upon exposure to ionizing radiation, water is decomposed into OH,

H, eaq-, H2, H2O2 and H3O+. Polymer radicals are formed upon hydrogen abstraction from the

polymer by OH and H. By saturating the aqueous solution with N2O, the strongly reducing

hydrated electron can be converted into a hydroxyl radical.

In the radiation synthesis of nanogels from polymer aqueous solutions, conditions that favor

intramolecular radical-radical reactions are generally employed. Interestingly, these are also

the conditions when scavenging of the primary radicals formed in the radiolysis of water is no

longer quantitative. Under these conditions, a fraction of the hydroxyl radicals can recombine

and produce hydrogen peroxide. This can have a significant influence on the further reactions

in the system. In systems exposed to a sequence of pulses, the formation of H2O2 will eventually

lead to the production of O2. It is therefore desirable to be able to perform both experiments

and numerical simulations on these systems both in order to confirm mechanistic and kinetic

data and to be used as a predictive tool for process optimization.

The obvious first step in the development of the modelling tool is the simulation of single pulse

irradiations to explore the effects of dose per pulse, concentration of polymer and polymer

molecular weight on the kinetics of polymer radical decay. The next step is to model more

complex pulse sequences that resemble conditions used to irradiate large volumes of aqueous

polymer solutions and produce nanogels.

The numerical simulation is based on a deterministic approach encompassing the conventional

homogeneous radiation chemistry of water as well as chemical reactions involving polymer

chains and polymer radicals. As benchmarking, results from a series of experiments on pulsed

irradiation of aqueous PVP-solutions have been used. The simulations qualitatively reproduce

the experimentally observed impact of initial gas saturation (air and N2O) and polymer

concentration on the molecular chain length upon irradiation. The formation of double bonds

as a function of dose as well as the impact of effective dose rate on the final chain length are

also qualitatively reproduced in the simulations and suggests different possible options for

irradiation conditions to tailor the molecular weight and functionality of the synthetized

nanogels to meet application requirements.

Acknowledgements

BD acknowledges the Royal Institute of Technology for financial support.

CD acknowledges the Institute of Nuclear Chemistry and Technology in Warsaw (Poland) for

performing the ebeam irradiations and IAEA CRP F22064.



86

Poster 33: Internal Structure and Composition of Fukushima-Derived

Particulate Revealed Through Combined Synchrotron and Mass-

Spectrometry Techniques

P.G. Martin1, S. Cipiccia2, D.J. Batey2, Y. Satou3 and T.B. Scott1

1School of Physics, University of Bristol, HH Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8

1TL 2Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE

3Japan Atomic Energy Agency (JAEA) - CLADS, Tomioka, Futaba-gun, Fukushima Prefecture, Japan

Despite the events at the Fukushima Daiichi Nuclear Power Plant (FDNPP) having passed

their eighth anniversary, a considerable amount of work is still ongoing to evaluate

the nature and environmental legacy of the radioactive particulate species [1,2].

Through the application of both laboratory and synchrotron radiation (SR) x-ray tomography

(XRT), the internal structure of a representative sub-mm particle was shown to be highly-

porous – with 24% of the internal volume constituted by void space (Figure 1). Compositional

(elemental) analysis of the particulate material through SR x-ray fluorescence (XRF) detailed

the peripheral enrichment of several elements (including Sr, Pb and Zr). The component of

fissionogenic Cs (134 + 135 + 137Cs) was determined to account for most of the elemental

abundance within the particle with limited contribution from natural 133Cs.

SR x-ray absorption near edge structure (XANES) analysis on several high atomic density

particles located within the bulk particle confirmed them to be U in composition, existing in

the U(IV) oxidation-state, as UO2. The complementary isotopic analysis of this micron scale

uranium material enclosed just below the surface of the particle was subsequently determined

using secondary ion mass spectrometry (SIMS), having spatially referenced their co-ordinate

positions between the different techniques. SIMS mapping revealed the U-rich particle to be

~1 μm in maximum dimension, consisting of enriched U with 3.54 wt% 235U – analogous to

that used in the reactor Unit 1 fuel assemblies [3].

References

[1] Imoto et al., (2017). Scientific Reports, 7 (5409) pp. 12.

[2] Furuki et al., (2017). Scientific Reports, 7 (42731) pp. 10. [3] Fukushima Daiichi NPS - Information Portal. TEPCO (2013).

Figure 1. SR-XRT reconstruction of the representative particle showing the 24% void volume.

Regions of both stainless-steel (orange) and cement (green) composition are shown (as identified

through SR-XRF), as are locations where voids are observed to interact.



87



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