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POSITRON ANNIIHILATION LIFETIME SPECTROSCOPY Fundamentals and applications

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.

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POSITRON ANNIIHILATION LIFETIME SPECTROSCOPY Fundamentals and applications

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  1. POSITRON ANNIIHILATION LIFETIME SPECTROSCOPYFundamentals and applications Bożena Jasińska Institute of Physics Maria Curie SklodowskaUniversity II SYMPOSIUM ON APPLIED NUCLEAR PHYSICS AND INNOVATIVE TECHNOLOGIES Jagiellonian University, Kraków, September 24 - 27, 2014

  2. 511 keV Annihilation _ + 511 keV

  3. outline • POSITRON AND POSITRONIUM • ETE MODEL • EXPERIMENTAL SETUP • METALS AND OXIDES • PHASE TRANSITION IN POLYMERS • POROUS MATERIALS

  4. 511 keV Annihilation _ + 511 keV

  5. POSITRONIUM in the vacuum PARAPOSITRONIUM • = 125 ps • lp-Ps= (7,98950 ± 0,00002) ns-1 ORTOPOSITRONIUM t = 142 ns lo-Ps= (7,03993 ± 0,00001) ms-1

  6. POSITRONINUM IN THE MATTER

  7. POSITRONIUM in the condensed matter thermallization Processes leading to o-Ps lifetime shortening: - ortho-para conversion - quenching - pick-off

  8. POSITRONIUM in the condensed matter pick-off process Shortening of the o-Ps lifetime value: 1 to 142 ns

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

  10. Porous materials

  11. Porous materials EXCITED STATES Spherical potential well

  12. 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:

  13. Porous materials PALS vs LN

  14. PALS Positron Annihilation Lifetime Spectroscopy 2.6y b+ 90.4%, EC 9.5% 1274 keV 511 keV 1.274 3.7ps b+ 0.006% g Dt 0 511 keV counts 1274 keV Channel number (energy)

  15. PAL spectrometer

  16. PAL spectrometer

  17. Lifetime spectrum

  18. Spectrum analysis – convolution („LT”) counts Time, ns J. Kansy, Nucl. Instr. Methods A374, 235 (1996).

  19. examples

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

  21. POLYMERS CYTOP Glass transition T=1080 C M. Śniegocka, PhD Thesis, Lublin 2010

  22. Phase transition in alkanes C13H28 C15H32 C17H36 C19H40 B. Zgardzińska, PhD Thesis, Lublin 2008

  23. pollution sorption photonics Low-k materials Porous materials

  24. Porous materials PHOTON ACTIVE GLASSES R = 0.99 nm R = 1.55 nm R = 2.38 nm http://chem.ch.huji.ac.il/~renata/

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

  26. Porous materials 1-PG, 2 – PG + dye 3 – PG + AgNPs

  27. Thank you for your attention Thank you for your attention

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