OPTICAL ABSORPTION AND FLUORESCENCE SPECTRA OF SINGLE-CRYSTAL TBF3

Absorption and fluorescence measurements on a single crystal of TbF3 have been used to prepare an energy-level scheme for the Stark components of the τF multiplet and the 5D4 level of Tb3+ in this crystal. The results are consistent with C, site symmetry for the rare-earth ion. In addition a limited set of measurements indicate that the 5D4 level decays with lifetimes of 3.9±0.4,0. 46±0.05, and 0.30±0.05 msec at 4.2, 77, and 300°K, respectively.