The FH‐Centre Energy Structure in KCl and KBr

Abstract

AbstractThe energy parameters of the FH(Br−)‐, FH(O−) — centres in KCl and FH(O−) — centres in KBr are calculated within the framework of perturbation theory. From the comparison of calculated and experimental data the following conclusions are drawn: (1) the long‐wave shift of the F‐centre absorption band in KCl with increasing Br− concentration may be due to the formation of FH(Br−)‐centres whose components are a \documentclass{article}\pagestyle{empty}\begin{document}$ a\sqrt 2 $\end{document} apart (a is the shortest interionic distance); (2) the decay of impurity excitons in KCl‐Br leads to the creation (or the manifestation in the stimulation spectrum) of the FH(Br−)‐centres with components being 2a rather than a \documentclass{article}\pagestyle{empty}\begin{document}$ a\sqrt 2 $\end{document} apart; (3) the change in the optical characteristics of the FH(O−)‐centre as compared to those of the F‐centre in KBr is consistent with the experiment assuming that an O− off‐centre position in the lattice site exists. The possibility of F‐centre RES life‐time lowering is mentioned.