Effect of intrinsic luminescence of alkali halide amplification by low temperature deformation

By using luminescence spectroscopy, we have established the influence of low-temperature uniaxial deformation on the configuration of a self-trapped exciton (STE) in alkali halide crystals (AHC) at the instant of radiative relaxation. In face-centered crystals, there occurs the redistribution of the luminescence intensity from the asymmetric configuration of STE to the symmetric one (III → II → I- types), whereas in volume-centered crystals, on the contrary, the evidence counts in favour of the asymmetric configuration of STE (I→ II–types). The external deformation in the direction leads to an effective sliding of anions in the direction that coincides with the direction of the STE squeeze which classically makes for the creation, of the symmetric STE configuration in the direction, acting perpendicularly to the STE’ length results in their stretching, which in turn brings into the creation of the asymmetric STE configuration with a higher degree of the polarization.