On the VUV and UV 4f 7( [formula omitted])5d→4f 8 interconfigurational transitions of Tb 3+ ions in LiLuF 4 single crystal hosts

Abstract

The laser induced fluorescence spectrum of Tb 3+ ions in LiLuF 4 single crystals, pumped by a fluorine pulsed discharge molecular laser at 157.6 nm, was obtained in the vacuum ultraviolet (VUV) and ultraviolet (UV) regions of the spectrum. The 4f 75d→4f 8 dipole allowed transitions originate from the Stark components and the edge of the levels of the 4f 7( 8 S )5d electronic configuration. The LIF spectra were interpreted on the basis of phonon trapping and phonon reabsorption within the levels of the 4f 75d electronic configuration. The absorption spectrum of the crystal samples in the VUV was obtained as well. We observed eight transitions between the ground level 4f 8( 7 F 6 ) and the Stark components of the levels of the 4f 7( 8 S )5d electronic configuration and five transitions between the ground level 4f 8( 7 F 6 ) and the Stark components of the levels of the 4f 7( 6 P )5d electronic configuration. The edge of the levels of the 4f 75d electronic configuration was found to be at 45.2×10 3±0.2×10 3 cm −1 and the band gap of the crystal host was 77.6×10 3±0.3×10 3 cm −1 wide.