Lengthening of the Sm2+ 4f55d → 4f6 decay time through interplay with the 4f6[5D0] level and its analogy to Eu2+ and Pr3+

Abstract

Recent research activity on Sm2+-doped compounds has significantly increased the amount of available data on 4f55d → 4f6 decay times. This enabled the systematic comparison of spectroscopic and time resolved luminescence data to theoretical models describing the interplay between the 4f55d and 4f6[5D0] excited states on the observed decay time. A Boltzmann distribution between the population of the excited states is assumed, introducing a dependence of the observed 4f55d → 4f6 decay time on the energy gap between the 4f55d and 4f6[5D0] levels and temperature. The model is used to interpret the origin of the large variation in reported 4f55d → 4f6 decay times through literature, and links their temperature dependence to applications such as luminescence thermometry and near-infrared scintillation. The model is further applied to the analogous situation of close lying 4fn-15d and 4fn states in Eu2+ (6P7/2) and Pr3+ (1S0).