Near-UV excited-state absorption spectra obtained with a pulsed pump–probe technique were recorded in LiYF4:Pr3+ at 77 and at 8 K and revealed a detailed structure of the 4f 2 1D2→4f5d and 4f 2 (3P0+1I6)→4f5d optical transitions. These experimental results, together with those previously obtained at room temperature, are compared with the numerical predictions of a full calculation of the 4f5d sublevels and of the electric dipole transitions toward these sublevels from different states of the 4f 2 configuration. The agreement is good, provided that the four adjustable parameters of the theory are taken as B20(5d)=7290 cm−1, B40(5d)=−14 900 cm−1, F0=60 557 cm−1, and 〈r〉fd=0.245 Å. The level structure of the 4f5d configuration of LiYF4:Pr3+ is shown to be dominated, as expected, by the crystal field coupling of the 5d electron but also, to a noticeable extent, by the spin–orbit coupling of the 4f electron and the Coulomb repulsion of both electrons. The former of these two interactions is somewhat more efficient than the latter in the low-energy part of the 4f5d configuration, i.e., in the spectral region where the largest amount of experimental data is currently available.
© 2000 Optical Society of AmericaPDF Article