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

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. • Luminescence properties of the A′, B′, and C′ bands in RbCl:Au− were investigated. • The decay profiles of these luminescence bands exhibit a single-exponential profile. • Temperature dependences of the luminescence intensities and decay time constants were analyzed by rate equations. • The 3E u and 3T 2u states are largely split in energy by a cubic crystal field. [ABSTRACT FROM AUTHOR]