positron anniihilation lifetime spectroscopy fundamentals and applications
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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
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