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Low‐Temperature Pair Associates of H Centres in KBr
Author(s) -
Akilbekov A.,
Elango A.
Publication year - 1984
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.2221220237
Subject(s) - halogen , impurity , absorption spectroscopy , absorption (acoustics) , annealing (glass) , ion , absorption band , chemistry , spectral line , crystallography , atomic physics , analytical chemistry (journal) , materials science , physics , optics , alkyl , organic chemistry , chromatography , astronomy , composite material
In the course of investigating the annealing of KBr crystals X‐rayed at 4.2 K the creation of new pair associates of interstitial halogen atoms (di‐H centres) with an absorption band at 3.85 eV is detected. The 3.85 centres arise only as a result of thermodestruction of the well‐known di‐H centres with an absorption band at 4.4 eV. The properties of these new centres are studied and the possible ways of halogen association in KBr are discussed. As a model for the 3.85 centres a model of (Br 2 − ) 2 dimers is proposed, in which the optical transition differs from that in Br 2 −ions both by size and direction. The range of KBr absorption spectra between Br 2 −and Br 3 −absorptions (3.6 to 4.4 eV) is attributed to the absorption of (Br 2 − ) 2 dimers. The V 4A centres in KBr with Li or Na impurities have obviously also a (Br − 2 ) 2 structure.