Vibronic transition probabilities in the excitation spectra of the Pr³⁺ion

Vibronic features are observed in the excitation spectrum of Pr 3+ in several host lattices. Vibronic transition probabilities, A VIB , for the 3 H 4 to 3 P 0 excitation transition on Pr 3+ are reported. A VIB varies by two orders of magnitude from LaF 3 to Y 2 O 2 S. These observations are discussed in terms of existing theories of the intensity of vibronic transitions in the intraconfigurational 4f n spectra. The observed variation can be qualitatively accounted for by the differences in covalency, polarizability and opposite-parity configuration admixing.