Exciton-like luminescence of KCl matrix under thermoelastic, local and uniaxial deformation

Abstract

The radiative relaxation of exciton-like formations in KCl-Na single crystal has been studied by exper-imental methods of luminescent spectroscopy. The amplifying effect of the radiation intensity with a maximum at 2.8 eV up to 500 times as compared to pure KCl has been detected in KCl-Na. The luminescence efficiency of an exciton-like formation increases with rise in: sodium ions concentration ( 10 ÷ 1000 ppm), thermal exposure ( 500◦C ÷ 600◦C ) and the degree of uniaxial deformation along and crystallographic directions. Previously, such a scale of the luminescence enhancement effect has not been registered in KCl matrix at room temperature. At high sodium concentrations (1000 ppm) in KCl-Na crystals, the additional intense emission with a maximum at 3.1 eV has also been revealed, which is typical for pair sodium ions. It is interpreted that the exciton-like formation in the sodium field with the maximum quantum yield of luminescence is formed by recombination assembly of electron-hole pairs due to the mobility of unrelaxed holes.

Keywords

• alkali halide crystals
• x-ray luminescence
• quenching
• local and uniaxial deformation
• self-trapped exciton
• exciton-like luminescence
• electron-hole recombination
• exciton-like formation