OH-DISSOCIATION AND U2 DECOMPOSITION IN HYDROXIDE-DOPED KCL AND KBR CRYSTALS

We report quantitative results concerning the dissociation of OH−, supporting the conception given first by Kerkhoff. U2 centres created by this reaction are thermally stable below about 100°K. It is shown that U2 centres can be destroyed by optical bleaching. At 4.5°K, U and H centres are created simultaneously; this is described as (Formula Presented.) We suggest for the underlying mechanism that the first process after U2 excitation is a noncubic relaxation of the lattice (static Jahn‐Teller effect) followed by a 〈110〉 replacement sequence as described by Williams to form a H‐centre–vacancy pair, the vacancy finally being occupied by the H− ion. – In KCl a reverse reaction can be induced either by thermal activation or by bleaching with H light. – Oscillator strengths of the U2, H, and OH− bands are calculated from the results using the Smakula equation. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim