OH− Dissociation and U2 Decomposition in Hydroxide‐Doped KCl and KBr Crystals

Abstract

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 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.