Positronium trapping in porous solids: Means and limitations for structural studies

Zs Kajcsos, L. Liszkay, G. Duplâtre, L. Varga, L. Lohonyai, F. Pászti, E. Szilágyi, K. Lázár, E. Kótai, G. Pál-Borbély, H. K. Beyer, P. Caullet, J. Patarin, M. E. Azenha, P. M. Gordo, C. Lopes Gil, A. P. De Lima, M. F.Ferreira Marques

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Abstract

Positron annihilation techniques are used for the structural investigation of solids but the interpretation of results in grainy and porous media is still unclear. A unique picture can be obtained assuming that the dominant process is Ps trapping in competing "extended free volume" sites. In samples with a large amount of free volumes near-saturation Ps trapping will rule the lifetime pattern, and very long lifetimes of over 100 ns might arise from o-Ps trapped in mesopores. It is shown that lifetime parameters must be corrected for the 8γ/2γ counting efficiency ratio. The results demonstrate the high sensitivity of Ps to mesopores in zeolites but also that Ps-trapping poses limitations on the applicability of lifetime to structural investigation in porous systems. The evolution of the lifetime spectra upon changes in the sample and measuring conditions should be considered in a complex way, observing not only changes in some selected components but in the whole lifetime pattern simultaneously.

Original languageEnglish
Pages (from-to)729-737
Number of pages9
JournalActa Physica Polonica A
Volume107
Issue number5
DOIs
Publication statusPublished - May 2005

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Kajcsos, Z., Liszkay, L., Duplâtre, G., Varga, L., Lohonyai, L., Pászti, F., Szilágyi, E., Lázár, K., Kótai, E., Pál-Borbély, G., Beyer, H. K., Caullet, P., Patarin, J., Azenha, M. E., Gordo, P. M., Gil, C. L., De Lima, A. P., & Marques, M. F. F. (2005). Positronium trapping in porous solids: Means and limitations for structural studies. Acta Physica Polonica A, 107(5), 729-737. https://doi.org/10.12693/APhysPolA.107.729