Tm3+ interactions in LiYF4 studied by high-resolution spectroscopy

We used the high-resolution spectroscopy to study the interactions that Tm3+ ion in a LiYF4 crystal is subjected to. Several crystal field transitions with low integral intensity were found not registered before by means of ordinary spectroscopy. Spectral evidences for interionic, hyperfine, isotopic interactions, and for a resonant broadening of the ground state are presented.