Pairs of F‐Centres and F− Impurities in KCl Studied by ENDOR

Abstract

AbstractBy optical bleaching of F‐centres in KCl doped with KF at −60 °C about half of the F‐centres can be converted into room temperature stable pairs of F‐centres and F− impurity ions, which have a single optical absorption band peaking at a 5% lower energy than the F‐centre. With electron nuclear double resonance (ENDOR) could be shown that the F− impurity resides in a [200] next‐nearest position and not in a [110] nearest halogen position. The K+ ion between the anion vacancy and the F− ion is displaced by ≈︁ 11% towards F−. Its superhyperfine constants show a strong temperature dependence.