Electronic states and relaxation dynamics of Au─ centers in RbCl crystals

Abstract

We investigated the electronic states and nonradiative transitions among the relaxed excited states of Au− centers in RbCl crystals. To this end, we measured the temperature dependences of the luminescence intensities and decay time constants of the A′, B′, and C′ luminescence bands, which are attributed to the radiative transitions from the relaxed excited states of Au− centers. The intensities and decay time constants of these luminescence bands change with temperature, through the thermally activated nonradiative transitions among the relaxed excited states. The temperature dependences of the luminescence intensities and decay time constants were analyzed utilizing rate equations, except the decay time constant of the C′ luminescence. From the best fitting results, the activation energies of the relaxed excited states are estimated. The C′ luminescence has a longer decay time constant than that expected from the dipole-allowed transition. The temperature dependence of the decay time of the C’ luminescence is discussed by considering a trapped level.