Site-selective laser spectroscopy of 4f(n)-4f(n-1)5d transitions in CaF2 :Pr3+ with F-, D-, H-, Li+, or Na+ charge compensation

Site-selective luminescence spectroscopy of the 4f(2)-4f5d(fd) transition i s reported for six different Pr3+ sites in CaF2:Pr3+. In addition to the na turally occurring distantly charge-compensated cubic site and the locally c harge-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 th ese different Pr3+ sites. For the H- and D- charge-compensated site the low est 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 emis sion spectra, the 4f5d-I-1(6), P-3(J) transitions are used to reveal marked differences between sites which allows their identification. (C) 2001 Amer ican Institute of Physics.