"Off-Center" Effect in the Relaxed Excited State ofCu+Substitutional in Alkali Halides

Abstract

Lifetime data on the $3d^{9}4s\to 3d^{10}$ forbidden transition of the substitutional ${\mathrm{Cu}}^{+}$ ion in several alkali halides are reported. From a detailed study of the temperature dependence of $\tau$ and the comparison with the known data on the temperature variation of the oscillator strength, $f\left(T\right)\mathrm{}$, it is concluded that the position in the lattice of ${\mathrm{Cu}}^{+}$ in the relaxed excited state and in the ground state may or may not be the same. In particular, it should be the same in the alkali iodides and NaCl, but different in the alkali bromides and KCl and RbCl.