Systematic investigations have been performed using positron annihilation techniques on micrograins of crystalline powders (e.g., MgO, Al2O3, SiO2) and on various zeolites (e.g., silicalite 1, Na-X, Na-Y, ZSM-5, mordenite) aiming at a better understanding of the formation and decay of the long-lived ortho-positronium states. The techniques were lifetime spectroscopy, Doppler-effect measurements and the recording of the full energy distribution of the annihilation radiation. The influences of heat treatment, sample evacuation and presence of gases were investigated. Lifetimes over 130 ns and o-Ps fractions of about 30% were found. A strong correlation of positron annihilation technique data with a water content of the samples was evidenced. Possible pictures of the formation and decay of ortho-positronium in porous media are discussed.
|Number of pages||8|
|Journal||Acta Physica Polonica A|
|Publication status||Published - Jan 1 2001|
|Event||32nd Polish Seminar on Positron Annihilation - Jarnoltowek, Poland|
Duration: Sep 18 2000 → Sep 22 2000
ASJC Scopus subject areas
- Physics and Astronomy(all)