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Thermal Properties of (F + 2 ) H and (F + 2 ) AH Centres in Alkali Halides
Author(s) -
Kawa E.,
Konaté A.,
Doualan J. L.,
Margerie J.
Publication year - 1997
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 - 10.1002/1521-3951(199701)199:1<15::aid-pssb15>3.0.co;2-m
Subject(s) - halide , physics , alkali metal , chemistry , analytical chemistry (journal) , inorganic chemistry , quantum mechanics , chromatography
Several thermal properties of (F + 2 ) H and (F + 2 ) AH centres are studied. (i) Positions and widths of the infrared absorption band have been measured as functions of temperature in seven cases; the results are discussed in the frame of a simple configuration coordinate model. (ii) The thermal stability of the (a) variety at room temperature is reported for a great number of (F + 2 ) H and (F + 2 ) AH centres. (iii) The spontaneous (b) → (a) transformation in the 150 to 250 K domain is briefly studied for eight (F + 2 ) H or (F + 2 ) AH centres and in more details in four cases. (iv) It is demonstrated that the so‐called “(b)” variety of (F + 2 ) H centres in NaCl:O 2— is really a mixture of two different species, probably the (a) variety and a (b 0 ) one, with relative proportions depending on the temperature of the “F‐light” irradiation which has converted (a) into “(b)”. An energy scheme is proposed to explain the behaviour of the (a) ― “(b)” intertransformations, both thermal and radiative.