On temperature dependence of impurity absorption and luminescence bands in dielectric crystals

In terms of the adiabatic approach to determining the states of an impurity dielectric crystal, the temperature dependence of the first moment (maximum) of the optical band that arises upon vibronic transitions in a local center is studied. It is shown that the frequency of the band maximum and absolute temperature are linked with each other by a relation that is analogous to the Wien’s displacement law for equilibrium radiation. This result is consistent with experimental data obtained, in particular for F absorption and luminescence bands in alkali halide crystals.