Site-selective laser spectroscopy of 4fn–4fn−15d transitions in CaF2:Pr3+ with F−, D−, H−, Li+, or Na+ charge compensation

Site-selective luminescence spectroscopy of the 4f2−4f5d(fd) transition is reported for six different Pr3+ sites in CaF2:Pr3+. In addition to the naturally occurring distantly charge-compensated cubic site and the locally charge-compensated Pr3+–F− site, charge compensating ions (H−, D−, Li+, and Na+) were added to create four other types of sites. In the fd luminescence spectra fine structure (zero-phonon lines and vibronic lines) is observed. The positions of zero-phonon lines and vibrational frequencies vary for these different Pr3+ sites. For the H− and D− charge-compensated site the lowest 4f5d level is shifted to some 3000 cm−1 lower energy compared to the cubic site. This is attributed to a higher degree of covalency and a larger crystal-field splitting. Contrary to previous results for Ce3+–H− and Ce3+–D−, only a small (close to zero) isotope shift is observed. In the fd emission spectra, the 4f5d–1I6, PJ3 transitions are used to reveal marked differences between sites which allows their identification.