Fundamentals and Dynamics of Energy Transport and Conversion

The Advanced Photon Source is funded by the U.S. Department of Energy Office of Science

Advanced Photon Source • 9700 S. Cass Ave. • Argonne, IL 60439 USA • www.aps.anl.gov • www.anl.gov

Opportunities for time-resolved x-ray science at the Advanced Photon Source

APS Standard Operating Mode

• Provides a large flux in well separated pulses

X-rays 6.52 MHz

153 ns80 ps

FWHM

X-ray pulse spacing is large enough to isolate signal from individual x-

ray pulses

~106 photons/pulse at 7ID-D

~1010 photons/pulse at 14ID-B

Diverse pump sources: Optical, electrical, mechanical and THz excitations

Electronic origin of photoinduced strain in multiferroics

Wen, et al., Phys. Rev. Lett. 110, 037601 (2013)Schick, et al., Phys. Rev. Lett. 112, 097602 (2014)

400 nm

35 nm BiFeO3 on SrTiO3 (001)

Using ultrafast optical and x-ray probes, we found optically excited carriers screen the depolarization field, which gives rise to significant localized strain as a result of inverse piezoelectric effect.

Motivation: Controlling the interplay of electronic, magnetic, optical, mechanical, and thermal properties of materials for efficient energy transport and conversion.

+-

+

+ -+

- -

+ +

-

+

-

t<0 t=0 t>0Complex chemical reactions can be initiated by light and recorded on physically relevant time scales, paving the way for the exploration of of life’s most sophisticated processes.

Y. O. Jung et al., Nature Chem. 5, 212(2013)

J. Chen, et al., Appl. Phys. Lett. 102, 181903 (2013).

Visualizing trans-cis isomerization pathways

Time- and momentum-resolved heat transport

Ultrafast Materials Science: Understanding and controlling energy transport and conversion among multiple degrees of freedom

Q

5um

0.3

0.5

0.16

-10 0 10 200.10

0.15

0.4ns

0.1ns

1ns

1.4ns

The spatiotemporal-resolved structural probe reveals the deviation of the relaxation process from a sinusoidal profile that quantitatively measure the in-plane transport processes.

IntroductionThe time-resolved research program at the Advanced Photon Source is targeted at understanding the fundamentals of energy transport and conversion at multi- energy, length and time scales utilizing a suite of advanced ultrafast hard x-ray probes localized at Sector 7, 11 and 14.

Spin

Charge

Lattice

Orbital

+-

+

+ -+

--

++

-

+

-

-+

-

+

+ -+

--

++

-

+

-+

-

+

+ -+

--

++

-

+

-c

a

Optical intensity I(x,t)

Lattice structure (x,t)

9.5

10.0

12

18

9

12

-20 -10 0 10 20

10

12

-2ns (18s)

0.1ns

4ns

20ns

Position (µm)

Inte

nsity

(a.

u)In

tens

ity (

a.u)

0 2 4 6 8 10 12

17

17.1

17.2

17.3

17.4

17.5

17.6

θ o

Delay (ns)

Energy transport in nanostructured materials

BiFeO3

FeRh

Ultrafast Chemical Science: Elucidating the mechanisms of light induced chemical processes

Dye Sensitized Solar Cells

Natural photosynthesis

Molecular machines

Artificial photosynthesis solar fuels: Light → chemical energy

Artificial photosynthesissolar cells: Light → electricity

Combined Techniques for Complimentary Information

XAS(absorption)

XES(emission)

XRS(scattering)

Kα, Kβ sensitive to electronic structure,

not geometric structure

(spin and oxidation state, electronic correlations)

Determine structures of transient

intermediates

Insight into solvent shell rearrangements

XANES: sensitive to electronic and

geometric structure (oxidation state, valence orbital occupancy, charge

transfer)

EXAFS: local bond distances and

coordination numbers

Element specific, sensitive to local structure

Sensitive to all species in the

solvent

Valence-to-Core sensitive to chemically

relevant orbitals

Motivation: harnessing the power of light

All those techniques can now be applied to study transient states !

X-ray absorption spectroscopy

X-ray emission spectroscopy

X-ray diffuse scattering

-direct probe of spin state

-insight into solvent shell rearrangements

Kα

Kβ

-electronic and geometric structure

Excited state fraction

Input for XAS analysis Input for

scattering analysis

EXAFS yields change in bond length

Yields excited state geometric structure

KB Mirrors

X-rays

Ionchamber

Pilatus

Laser

APD

1 m Rowland circle

Analyzer crystal

Scintillator

3 ft. x 3 ft.table

Liquid jet

Capturing excited state structures at high precision by using full APS flux

First demonstration of combined techniques in a pump-probe experiment

Low spin ~t 650 ps

hn

Aqueous [Fe(bpy)3]2+

High spin

K. Haldrup et al., J.Phys Chem. A 116, 9878 (2012) G. Vanko et al, JESRP 188, 166 (2013)

Sector 7ID-D

Combined techniques

setup

Using flux demanding techniques for time resolved studies: efficient detection at high rep-rate

Ex: Von Hamos crystal analyzer for TR-XES

J. Szlachetko et al., RSI 83, 103105 (2012).

X-ra

y em

issi

on e

nerg

y

Incident x-ray energy

ZnO nanoparticles: Observe evolution of charge distribution

Laser excitation and x-ray detection @ 1.3 MHz

ZnO (35 nm particles) in water @355 nm

Optical pulse promotes electrons in conduction band

Only ~1% excited state fraction

Time-resolved RIXS difference map

Data consistent with increased electron density on Zn centers

Also demonstrated simultaneous measurement of Ka, Kb and Valence to Core XES

Kb 100 ps delay

Ka 100 ps delayK a ground state

K b ground state

Photosystem 1

e -

Relay

Catalyst

Photosensitizer(PS)

Relay(R)

Catalyst(C)

R

Bio-inspiration

Pho

tose

nsiti

zer

Phys. Chem. Lett. 4, 1972 (2013).

Natural photosynthesis

Interfacial electron transfer in Dye-sensitized solar cell

h

VB

CBDye

(TiO2)n

e -

VB

CBDye

(TiO2)n

+

-

X-ray probe

J. Phys. Chem. Lett. 2, 628 (2011). Angew. Chem. Int. Ed. 51, 12711 (2012).

Electron transfer inside a biomimetic supramolecular complex for solar fuel catalysts

Science 337, 1200 (2012).

Electron transport inside iron oxide nanoparticles

Sector 11ID-D

A versatile Time resolved

X-Ray Absorption

setup

Showcase experiments using X-ray absorption

Energy Conversion

Resolution: ~260 nm, ~80 ps

Spatiotemporally resolved hard x-ray probeHigh repetition rate lasers to fully exploit high flux of the APS

Tunable (0.2-16 mm)

Up to 1 MHz

250 fs

Light Conversion PHAROSNew!

266 nm 2.5 W (4 μJ/pulse) @ 600 kHz

Time Bandwidth DUETTO

50 kHz - 6.52 MHz

10 ps and 130 ps

Electric field pulse

THz radiation@Sec7

Laser shock excitation

Optical excitation

Energy Transport

0.4% strain

Electric-field-driven domain dynamics

P. Chen, et al., Phys. Rev. Lett. 110, 047601 (2013)

The time-resolved changes of the diffuse scattering show primarily a quasi-thermal phonon distribution that is established in 100 ps and that follows the time-scale of thermal transport.

Superionic phase transition

T. A. Miller et al., Nature Comm. 4, 1369 (2013)

H. Wen, G. Doumy, B. Adams, A. D. DiChiara, E. M. Dufresne, T. Graber, Y. Li, A. M. March, Q. Kong, A. R. Sandy, S. H. Southworth, D. A. Walko, J. Wang, X. Zhang, Y. ZhuTime-Resolved Research, Atomic Molecular and Optical Physics, and Structural Science Groups,X-ray Science Division, Advanced Photon Source, Argonne National Laboratory

Position (µm)

PbO

SrO

PbO

TiO2

TiO2

TiO2

TiO2

TiO2

TiO2

TiO2

SrO

……