Some features of the deactivation of the Cr3+-ion excited states in crystals

An investigation was made of the influence of energy barriers determining the rates of exchange between thermally coupled levels on the laws governing the deactivation of excited impurity centers in crystals. It was found that by taking into account the barriers determining the rates of thermal exchange between the ²E and ⁴T₂ levels, it is possible to explain the temperature dependences of the luminescence spectrum and of the decay kinetics of the excited states of the Cr³⁺ ion. The probabilities of radiative transitions from the ²E and ⁴T₂ levels and the energy gap between the lowest vibrational states of these levels were determined for a YSAG:Cr³⁺ crystal. It was predicted theoretically and established experimentally that there are temperature ranges with exponential and nonexponential decay laws for the luminescence of the Cr³⁺ ion.