Transcript Positron Annihilation Lifetime Spectroscopy. Fundamentals and

POSITRON ANNIIHILATION
LIFETIME SPECTROSCOPY
Fundamentals and applications
Bożena Jasińska
Institute of Physics
Maria Curie Sklodowska University
II SYMPOSIUM ON APPLIED NUCLEAR PHYSICS
AND INNOVATIVE TECHNOLOGIES
Jagiellonian University, Kraków, September 24 - 27, 2014
511 keV
Annihilation
+
511 keV
_
outline
1. POSITRON AND POSITRONIUM
2. ETE MODEL
3. EXPERIMENTAL SETUP
4. METALS AND OXIDES
5. PHASE TRANSITION IN POLYMERS
6. POROUS MATERIALS
511 keV
Annihilation
+
511 keV
_
POSITRONIUM in the vacuum
PARAPOSITRONIUM
 = 125 ps
lp-Ps = (7,98950 ± 0,00002) ns-1
ORTOPOSITRONIUM
 = 142 ns
lo-Ps = (7,03993 ± 0,00001) ms-1
POSITRONINUM
IN THE
MATTER
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
R
0
L .O . R o e lig " P o s itro n A n n ih ila tio n " ( 1 9 6 7 ) 1 2 7
A .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
R
0
R 0 = R + R
S .J . T a o , J . C h e m . P h y s . 5 6 ( 1 9 7 2 ) 5 4 9 9
M . E l d r u p e t a l . C h e m .P h y s . 6 3 ( 1 9 8 1 ) 5 1
POSITRONIUM in the condensed matter
1/ λpo=λbP
R 
P  4

 (r ) r 2 dr
2
R
l po
R
1
R 

 lb 1 

sin 2

R   2
R

Lifetime, ns
8
sph
ell
6
cube
4
2
0
0.0
Dependence of the mean
o-Ps lifetime value
on the free volume size
and shape
cuboid
0.2
0.4
0.6
3
V, nm
0.8
1.0
Porous materials
Porous materials
EXCITED STATES
Spherical potential well
2
 2 Xnl
Enl 
2m Ps R 02
2d
1g
2p
1f
2s
1d
1p
1s
Porous materials
ETE model
Decay constanst of pick-off process (averaged over all populated states) :
l po 
 E (R )
 l i ( R )g i e x p   i
kT 

i1
N
 E i (R )
.
kT 

N
 g i exp
i1
Decay constant for nl-th state, spherical shape:
X nl
lnlpo  l b

X R/R
X nl
jl2 (r )r 2dr
nl
0
0
jl2 (r )r 2dr
Decay constant of nm-th state, cyllindrical shape:
X nl
lnlpo  l b

X R/R
X nl
jl2 (r )r 2dr
nl
0
0
jl2 (r )r 2dr
K. Ciesielski, A.L. Dawidowicz, T. Goworek, B. Jasińska and J. Wawryszczuk, Chem. Phys. Lett., 289,
41, (1998).
T. Goworek, K. Ciesielski, B. Jasińska and J. Wawryszczuk, Chem. Phys. 230, 305, (1998).
Porous materials
PALS vs LN
22
11
PALS
2.6y
Positron Annihilation Lifetime Spectroscopy
1274 keV
b+ 90.4%, EC 9.5%
511 keV
1.274
3.7ps
g
t
0
511 keV
counts
Na
1274 keV
Channel number (energy)
22
10
Ne*
b+ 0.006%
22
10
Ne
PAL spectrometer
PAL spectrometer
Lifetime spectrum
Spectrum analysis – convolution („LT”)
counts
Zi t  
t
Ii
exp  
i
 i 
Time, ns

N t   N 0  R t  t ' Z t ' dt '  T
0
J. Kansy, Nucl. Instr. Methods A 374, 235 (1996).
examples
Defected metal
counts
Nondefected metal
time
time
Fitted components:
1. Mean lifetime value
()
2. Intensity of i-th component
(I)
POLYMERS
CYTOP
0.6
0.5
Vh [nm3]
3 [ns]
5.5
4.5
0.4
0.3
3.5
0.2
Glass transition
T=1080 C
2.5
-200
-100
0
100
200
0.1
100
200
T [oC]
300
T [K]
M. Śniegocka, PhD Thesis, Lublin 2010
400
500
Phase transition in alkanes
C13H28
3.2
C15H32
 ns
2.8
2.4
C17H36
2
C19H40
1.6
1.2
240
250
260
270
280
290
TEMPERATURA, K
300
B. Zgardzińska, PhD Thesis, Lublin 2008
310
320
Porous materials
Low-k
materials
pollution
sorption
photonics
Porous materials
PHOTON ACTIVE GLASSES
100
40
R = 0.99 nm
R = 1.55 nm
R = 2.38 nm
30
INTENSITY, %
LIFETIME, ns
80
60
40
20
10
20
0
0
100
200
300
TEMPERATURE, K
400
500
100
200
300
TEMPERATURE, K
http://chem.ch.huji.ac.il/~renata/
400
500
Porous materials
dI/d
0.012
MCM-41
0.008
0.004
0
0
20
40
60
80
100
120
140
, ns
0.08
dV/dD
0.06
0.04
0.02
0
0.6
0.8
1
2
4
6
8
10
20
D, nm
[1] R. Zaleski, PhD thesis, Lublin (2005)
40
60
Porous materials
1 - PG,
2 – PG + dye
3 – PG + AgNPs
Thank
you
for
your
attention
Thank you for your attention