Theoretical and experimental study of positron annihilation with core electrons in solids

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
1996
Major/Subject
Mcode
Degree programme
Language
en
Pages
2397-2409
Series
Physical Review B, Volume 54, Issue 4
Abstract
A theory for calculating the momentum distribution of annihilating positron-electron pairs in solids is presented. To test the theory, momentum distributions are measured by the Doppler broadening of the annihilation radiation for several bulk metals and semiconductors, as well as for semiconductor alloys and for positrons trapped at vacancies in semiconductors. The theory is based on a two-particle description of the annihilating electron-positron pair. Then, the electron-positron correlation effects, i.e., the enhancement of the electron density at the positron, depend on the electronic state in question. The theory is suited for calculating the high-momentum part of the annihilation spectrum that arises from the core electrons and which can be measured by the Doppler broadening using coincidence techniques. The ideas of the theory are justified by a good agreement between theory and experiment in the case of positron annihilation in undefected bulk lattices. Moreover, the comparison of the theoretical and experimental spectra for alloys and vacancy defects tests the theoretical description for the positron distribution in delocalized and localized states, respectively.
Description
Keywords
positron annihilation, solids, core electrons
Other note
Citation
Alatalo, M. & Barbiellini, B. & Hakala, M. & Kauppinen, H. & Korhonen, T. & Puska, M. J. & Saarinen, K. & Hautojärvi, P. & Nieminen, Risto M. 1996. Theoretical and experimental study of positron annihilation with core electrons in solids. Physical Review B. Volume 54, Issue 4. 2397-2409. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.54.2397.