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A Bound State of Positrons with Sulphate Ions
Author(s) -
Serna J.,
Troev T.
Publication year - 1995
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221920108
Subject(s) - positronium , positron , ion , annihilation , atomic physics , electron , spectral line , bound state , barium , oxygen , impurity , covalent bond , materials science , chemistry , physics , inorganic chemistry , nuclear physics , organic chemistry , quantum mechanics , astronomy
Positron lifetime spectra are obtained in four different single crystals of sulphates: sodium, strontium, barium, and lead sulphate. The spectra can be resolved into four components, although only the intermediate ones are significant since the other components, with a very low intensity percentage, are associated to positronium formed at the interface of the source with the specimen. The intermediate short‐lived component is associated with the annihilation of the outer electrons of the oxygen ions. The annihilation of positrons in cation vacancies or in interstitial impurities may also contribute to this component. Annihilation in other defects, like clusters of vacancies, is associated with the intermediate long‐lived component, whose main contribution seems to be a bound state of positrons with electrons belonging to the covalent bonds between sulphur and oxygen.