Cathodoluminescence of KCl:Br crystals

Full text: In this paper the luminescence spectra in KCl:Br crystals using nanosecond time-resolved pulsed spectroscopy at low temperature have been studied. Kinetic characteristics of impurity excitons were investigated in KCl:Br (0.1M %) crystals by temperatures range of 27 K after the influence of pulse electron beam. The cathodoluminescence (CL) emission of KCl:Br consist of three broad emission bands: 4.88 eV , 3.6 eV, 2.55 eV. The 4.88 eV and 3.6 eV emission bands originate from the pared Br- ions at the nearest neighbor site (Br- dimer), since a probability of finding dimmers must be proportional to the square of the concentration of Br- ions as far as the concentration is low enough. The origin of the 2.55 eV emission band is tentatively assigned it the relaxed excited state of Br- monomer centers, [ClBr+ e]. Specimens used in the present study were cleaved from single crystals of KCl:B: which were grown in our laboratory by the Kyropoulos. Samples with a size of 10 x 10 x 8 mm3 were mounted on the copper block of a cryostat to which Au:Cu vs chromel thermocouple was attached to estimated the temperature. We use pulsed spectrometry method nanosecond resolution at temperatures of 27 K. The beam parameters are the following electrons energy ∼400 keV, ∼20 ns. We found two definite emission bands: 2.8 eV and 2.15 eV. In all cases the emission spectra can be decomposed into three Gaussian bands, as indicated by broken curves. We suggested that this band is originated from the relaxed excitons of the [Cl2-+e] type perturbed by the nearest neighbor Br- ions