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Study of Colour Centres in BaCl 2 and BaBr 2
Author(s) -
Houlier B.,
Yuste M.,
Chapelle J. P.,
Taurel L.
Publication year - 1972
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.2220510246
Subject(s) - hyperfine structure , ion , tensor (intrinsic definition) , chemistry , symmetry (geometry) , analytical chemistry (journal) , crystallography , atomic physics , physics , mathematics , geometry , organic chemistry , chromatography
After additive or electrolytic coloration, BaCl 2 , and BaBr 2 , single crystals exhibit F‐centres, whose proper symmetry is C 3 . The hyperfine spectrum in BaCl 2 can be accounted for with the assumption that there exist two types, F I and F II , of F‐centres, and that each hyperfine constant referring to a Ba 2+ ion ( k ) is given by an empirical expression a k = g N A / d k 3 , where d k is the distance between the ion k and the F‐centre. The two types of F‐centres have the same g‐tensor with principal values, in the case of BaCl 2 , gXX = 1.966; gYY = 1.976; gZZ = 1.986. The F‐centres can be optically bleached at room temperature, and then regenerated by heating above 100 °C.