Temperature Behavior of the Blue Fluorescence of Zns:Tm3+ Crystals

Abstract

The temperature behavior of the fluorescence spectra of Tm3+ impurity ions in cubic ZnS crystals in the blue range was studied either under selective, high-density excitation by nitrogen and dye laser beams or under non-selective excitation by a deuterium lamp in the temperature range from 4.2K to room temperature. At room temperature a structureless non-selectively excited fluorescence band ranging from 470 to 485 nm was observed, while at liquid nitrogen temperature and lower we observed more than 30 narrow fluorescence lines, the half widths of which were about 0.14 nm. The blue strongly temperature dependent fluorescence depends on the energy of excitation. This means that this fluorescence is either host-sensitized by an energy of excitation above the band gap energy of ZnS (E(cub.) = 3.78 eV at T = 77 K), or impurity excited by an energy of excitation below the band gap energy of ZnS.