Luminescence of NaCl—I. Electron and ion beam excited spectra

Abstract

Luminescence from a wide range of NaCl crystals of different purity has been excited by electrons and ion beams. Despite the range of crystal quality there are many similarities between the spectra excited under similar conditions. At both 77 and 300 K there is strong emission near 2.4 eV in all samples but the so called “intrinsic π emission” near 3.4 eV is sensitive in position to the source of the crystals and is readily suppressed by the presence of imperfections. In the energy range between 2.4 and 3.4 eV many component features can be detected. These are most easily resolved in the impure samples. The form of the spectra is sensitive to the total irradiation dose, dose rate and lifetime-resolved components. The reasons for the changes are briefly discussed in terms of a possible model of exciton states which are perturbed after exciton diffusion to imperfections.