POSITRON ANNIIHILATION LIFETIME SPECTROSCOPYFundamentals and applications

Bożena JasińskaInstitute of Physics

Maria Curie Sklodowska University

II SYMPOSIUM ON APPLIED NUCLEAR PHYSICS AND INNOVATIVE TECHNOLOGIES

Jagiellonian University, Kraków, September 24 - 27, 2014

+_

511 keV

511 keV

Annihilation

outline

1. POSITRON AND POSITRONIUM2. ETE MODEL 3. EXPERIMENTAL SETUP

4. METALS AND OXIDES5. PHASE TRANSITION IN POLYMERS6. POROUS MATERIALS

+_

511 keV

511 keV

Annihilation

POSITRONIUM in the vacuum

= 125 psp-Ps = (7,98950 ± 0,00002) ns-1

= 142 nso-Ps = (7,03993 ± 0,00001) ms-1

PARAPOSITRONIUM

ORTOPOSITRONIUM

POSITRONINUMPOSITRONINUMIN THE IN THE

MATTERMATTER

POSITRONIUM in the condensed matter

thermallization

Processes leading to o-Ps lifetime shortening:- ortho-para conversion- quenching- pick-off

POSITRONIUM in the condensed matter

pick-off process

Shortening of the o-Ps lifetime value: 1 to 142 ns

0R R = R + RR 0 0L .O . R o e lig " P o s itro n A n n ih ila tio n " (1 9 6 7 ) 1 2 7A .P . B u c h ik h in e t a l. Z E T F 6 0 (1 9 7 1 ) 1 1 3 6

S .J . T a o , J .C h e m .P h y s . 5 6 (1 9 7 2 ) 5 4 9 9M . E ld ru p e t a l. C h e m .P h y s . 6 3 (1 9 8 1 ) 5 1

R

R

22drr)r(4P

R

R2sin

2

1

R

R1bpo

1λpo=λbP

0.0 0.2 0.4 0.6 0.8 1.0

V, nm

0

2

4

6

8

Life

time,

ns

sphe ll

cube

cuboid

3

Dependence of the mean o-Ps lifetime value on the free volume sizeand shape

POSITRONIUM in the condensed matter

Porous materials

1 s

1 p

1 d2 s

1 f

2 p1 g

2 d

20

2nl

Ps

2

nlR

X

m2E

EXCITED STATESSpherical potential well

Porous materials

Decay constant for nl-th state, spherical shape:

Decay constanst of pick-off process (averaged over all populated states) :

T. Goworek, K. Ciesielski, B. Jasińska and J. Wawryszczuk, Chem. Phys. 230, 305, (1998).

K. Ciesielski, A.L. Dawidowicz, T. Goworek, B. Jasińska and J. Wawryszczuk, Chem. Phys. Lett., 289, 41, (1998).

ETE model

.k T

)R(Ee x pg

k T)R(E

e x pg)R(N

1i

ii

N

1i

iiipo

drr)r(jdrr)r(j 22l

X

0

X

R/RX

22lb

nlpo

nlnl

0nl

drr)r(jdrr)r(j 22l

X

0

X

R/RX

22lb

nlpo

nlnl

0nl

Decay constant of nm-th state, cyllindrical shape:

Porous materials

PALS vs LN

Porous materials

2.6y

3.7ps

+ 90.4%, EC 9.5%

+ 0.006%

Na2211

*2210 Ne

Ne2210

1.274

0

PALSPositron Annihilation Lifetime Spectroscopy

1274 keV 511 keV

t

511 keV

1274 keV

co

un

ts

Channel number (energy)

PAL spectrometer

PAL spectrometer

Lifetime spectrum

TdttZttRNtN

''

0

'0

Spectrum analysis – convolution („LT”)

J. Kansy, Nucl. Instr. Methods A 374, 235 (1996).

ii

ii

texp

ItZ

Time, ns

cou

nts

examples

Fitted components:

2. Intensity of i-th component

(I)

1. Mean lifetime value

()

Defected metal

time time

cou

nts

Nondefected metal

-200 -100 0 100 200

T [oC ]

2.5

3.5

4.5

5.5

3 [n

s]

100 200 300 400 500

T [K ]

0.1

0.2

0.3

0.4

0.5

0.6

Vh [n

m3 ]

CYTOP

Glass transitionT=1080 C

M. Śniegocka, PhD Thesis, Lublin 2010

POLYMERS

240 250 260 270 280 290 300 310 320TEM PER A TU R A, K

1.2

1.6

2

2.4

2.8

3.2

ns

Phase transition in alkanes

C13H2

8C15H3

2C17H3

6C19H4

0

B. Zgardzińska, PhD Thesis, Lublin 2008

Low-kmaterials

pollution sorption

photonics

Porous materials

100 200 300 400 500TEM PER ATU R E, K

0

20

40

60

80

100

LIF

ET

IME

, ns

100 200 300 400 500TEM PER ATU R E, K

0

10

20

30

40

INT

EN

SIT

Y, %

R = 0.99 nmR = 1.55 nm

R = 2.38 nm

http://chem.ch.huji.ac.il/~renata/

PHOTON ACTIVE GLASSES

Porous materials

0 20 40 60 80 100 120 140

, ns

0

0.004

0.008

0.012dI

/d

MCM-41

1 102 4 6 8 20 40 600.80.6

D, nm

0

0.02

0.04

0.06

0.08

dV/d

D

Porous materials

[1] R. Zaleski, PhD thesis, Lublin (2005)

110 115 120 125 130 135

LIFETIME [ns]

10-5

10-4

10-3

10-2

10-1

INT

EN

SIT

Y

1 - PG, 2 – PG + dye3 – PG + AgNPs

Porous materials

Thank you for your attention Thank you for your attention