4f n-15d→4f n emission of Ce 3+, Pr 3+, Nd 3+, Er 3+, and Tm 3+ in LiYF 4 and YPO 4

High-resolution 4f n-15d→4f n emission spectra in the (vacuum) ultraviolet are reported for Ce 3+, Pr 3+, Nd 3+, Er 3+, and Tm 3+ in LiYF 4 and YPO 4 host lattices. The positions and intensities of the zero-phonon lines are calculated and compared to the high-resolution emission spectra. For the thulium samples gated detection has been used to distinguish between the spin-forbidden and spin-allowed 4f n-15d→4f n emissions. Luminescence lifetimes for the spin-forbidden 4f n-15d→4f n emissions are calculated and compared with experimentally observed lifetimes. A good agreement between experiment and theory is found, demonstrating the validity of the model developed for the 4f n-15d and 4f n states of lanthanide ions.