Optical properties of Au ~- centers in CsBr and CsI single crystals

摘要

The temperature dependence of the absorption and luminescence spectra has been investigated for Au - centers in CsBr and CsI single crystals with the CsCl structure. In addition to the A, B, C, and D absorption bands, the A' and B' luminescence bands caused by the intraionic transitions in the Au - ion are observed at 12 K. The luminescence bands are characterized by a small Stokes shift and a narrow halfwidth, reflecting a weak electron-phonon interaction. Furthermore, the photoexcitation at the energies corresponding to the A, B, and C absorption bands induces luminescence bands in the visible energy region. The A', B', and visible luminescence bands change with temperature while complementing each other. The features of the Au - centers in cesium halides and the nonradiative transitions between the relaxed excited states are discussed.