An investigation was made of the A absorption band of the Au− center in KClxBr1−x crystals. In Au−-doped KCl and KBr crystals, the obvious zero-phonon lines and vibronic structures appeared in the absorption and luminescence spectra and reflected the relatively weak electron-lattice interaction. With increasing concentration of the other halogen ions, the zero-phonon lines and vibronic structures in the spectra suddenly disappeared, the absorption and luminescence bands became broader, and their Stokes–shift increased. This implied an increase in the electron-lattice interaction strength in the mixed crystals. The A absorption band at various temperatures could be deconvoluted into 2 Gaussian components due to the Jahn–Teller splitting. The temperature-dependence of the splitting energy revealed the presence of a static perturbation, due to a lowering of the site-symmetry of the impurity, in addition to the dynamic Jahn–Teller effect.

Jahn-Teller Effect of Au− Centers in KClxBr1−x Mixed Crystals. T.Kawai, Y.Sugata, S.Shimanuki: Journal of Luminescence, 2000, 87-89, 636-8