Oscillatory rule in the energy spectrum of traps in KCl and NaI crystals

TL;DR

This study reveals an oscillatory pattern in the energy spectrum of traps in KCl and NaI crystals, linked to vibrational modes, and confirms a model of thermoluminescence involving two-stage recombination processes.

Contribution

It introduces the discovery of an oscillatory energy spectrum in alkali-halide crystals and confirms a theoretical model of thermoluminescence mechanisms in these materials.

Findings

Energy spectrum of traps shows oscillatory behavior with vibrational quantum energies.

Quantum energies follow an oscillatory rule with half-integer and integer quantum numbers.

Confirmed the model involving two-stage recombination of H-centers in alkali-halide crystals.

Abstract

The thermoluminescence (TL) method is used for the investigation of the energy spectrum of traps in KCl and NaI crystals in the temperature range 80-500 K. It is shown that the thermal activation energies of traps in KCl and NaI form one oscillatory series E=hwn with vibrational quantum energies of 0.121 eV in KCl and 0.061 eV in NaI. In this case, the quantum number n assumes half-integer and integer values. Based on the generalized data on the investigated alkali-halide crystals (AHC), we confirmed the earlier proposed model of TL in AHCs. It is assumed that, in addition to the nonradiative H-F recombination, there exists the two-stage recombination of H-centers at anion vacancies resulting in the radiative recombination of a hole at an F-center. The energy of a quantum in the oscillatory rule corresponds to a local vibrational mode of an X2 halide molecule.