Intensities of electronic Raman scattering between crystal-field levels ofCe3+inLuPO4: Nonresonant and near-resonant excitation

The relative intensities of the electronic Raman scattering between individual crystal-field states of the 4$f^1$ configuration of ${\mathrm{Ce}}^{3+}$ in ${\mathrm{LuPO}}_4$ are compared to those calculated with use of the standard second-order theory, and also by explicitly evaluating the sum over the virtual intermediate states using the crystal-field wave functions and observed energies of the 5$d^1$ configuration. The results show that the explicit calculation predicts the observed relative intensities much more accurately than the standard theory. In addition, a change in the incident laser energy from the argon-ion green line (514.5 nm) to that of the frequency-tripled output of a ${\mathrm{Nd}}^{3+}$:YAG (355 nm) laser results in enhancements of the electronic Raman scattering intensities by factors on the order of 100. These enhancements are accurately predicted by the explicit calculation.