POSITRON ANNIIHILATION LIFETIME SPECTROSCOPY Fundamentals and applications Boena

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 ke. V Annihilation + 511 ke. V _

outline 1. POSITRON AND POSITRONIUM 2. ETE MODEL 3. EXPERIMENTAL SETUP 4. METALS AND OXIDES 5. PHASE TRANSITION IN POLYMERS 6. POROUS MATERIALS

511 ke. V Annihilation + 511 ke. V _

POSITRONIUM in the vacuum PARAPOSITRONIUM t = 125 ps lp-Ps = (7, 98950 ± 0, 00002) ns-1 ORTOPOSITRONIUM t = 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

POSITRONIUM in the condensed matter 1/t =λpo=λb. P Dependence of the mean o-Ps lifetime value on the free volume size and shape

Porous materials

Porous materials EXCITED STATES Spherical potential well

Porous materials ETE model Decay constanst of pick-off process (averaged over all populated states) : Decay constant for nl-th state, spherical shape: Decay constant of nm-th state, cyllindrical shape:

Porous materials PALS vs LN

PALS 2. 6 y Positron Annihilation Lifetime Spectroscopy 1274 ke. V b+ 90. 4%, EC 9. 5% 511 ke. V 1. 274 3. 7 ps g Dt 0 counts 511 ke. V 1274 ke. V Channel number (energy) b+ 0. 006%

PAL spectrometer

PAL spectrometer

Lifetime spectrum

counts Spectrum analysis – convolution („LT”) Time, ns J. Kansy, Nucl. Instr. Methods A 374, 235 (1996).

examples

Defected metal counts Nondefected metal time Fitted components: 1. Mean lifetime value (t) 2. Intensity of i-th component (I)

POLYMERS CYTOP Glass transition T=1080 C M. Śniegocka, Ph. D Thesis, Lublin 2010

Phase transition in alkanes C 13 H 28 C 15 H 32 C 17 H 36 C 19 H 40 B. Zgardzińska, Ph. D Thesis, Lublin 2008

Porous materials Low-k materials pollution sorption photonics

Porous materials PHOTON ACTIVE GLASSES R = 0. 99 nm R = 1. 55 nm R = 2. 38 nm http: //chem. ch. huji. ac. il/~renata/

Porous materials MCM-41 [1] R. Zaleski, Ph. D thesis, Lublin (2005)

Porous materials 1 - PG, 2 – PG + dye 3 – PG + Ag. NPs

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