Jahn–Teller effect of Au − centers in KCl xBr 1− x mixed crystals

Abstract

We have investigated the A absorption band of the Au − center in KCl x Br 1− x mixed crystals. In Au −-doped KCl and KBr crystals, the obvious zero-phonon lines and vibronic structures appear on the absorption and luminescence spectra reflecting the fairly weak electron–lattice interaction. With increasing concentration of the hetero-halogen ions, the zero-phonon lines and the vibronic structures on the spectra disappear abruptly, the absorption and luminescence bands become broader and their Stokes–shifts increase. These facts evidently indicate the increase in the electron–lattice interaction strength in the mixed crystal system. The A absorption band at various temperatures can be deconvoluted into two Gaussian components due to the Jahn–Teller splitting. The temperature dependence of the splitting energy reveals the presence of a static perturbation due to the lowering of the site symmetry of impurity in addition to the dynamical Jahn–Teller effect.