VUV and UV Florescence and Absorption Studies of Tb3+ and Tm3+ Trivalent Ions in LiYF4 Single Crystal Hosts

The laser induced fluorescence spectra of LiYF 4 :Tb 3+ (YLF:Tb) and LiYF 4 :Tm 3+ (YLF:Tm) single crystals, pumped by an F 2 pulsed discharge molecular laser at 157 nm, were obtained in the vacuum ultraviolet (VUV) and ultraviolet (UV) regions of the spectrum, at room temperature. A number of new fluorescence peaks were observed for the first time. They were assigned to the dipole allowed transitions 4f 7 5d → 4f 8 and 4f 11 5d → 4f 12 of Tb 3+ and Tm 3+ ions respectively. The absorption spectra of the same crystal samples in the VUV and UV regions were taken as well. The edge (onset) and the energy of the states with 4f N − 1 5d configuration were determined.