Jahn-Teller effect of Au- centers in KClxBr1-x mixed crystals

We have investigated the A absorption band of the Au- center in KClxBr1-x m ixed crystals. In Au- -doped KCl and KBr crystals, the obvious zero-phonon lines and vibronic structures appear on the absorption and luminescence spe ctra reflecting the fairly weak electron-lattice interaction. With increasi ng concentration of the hetero-halogen ions, the zero-phonon lines and the vibronic structures on the spectra disappear abruptly, the absorption and l uminescence bands become broader and their Stokes-shifts increase. These fa cts evidently indicate the increase in the electron-lattice interaction str ength in the mixed crystal system. The A absorption band at various tempera tures can be deconvoluted into two Gaussian components due to the Jahn-Tell er splitting. The temperature dependence of the splitting energy reveals th e presence of a static perturbation due to the lowering of the site symmetr y of impurity in addition to the dynamical Jahn-Teller effect. (C) 2000 Els evier Science B.V. All rights reserved.