Ce3+ and Pr3+5d-energy levels in the (pseudo) perovskites KMgF3 and NaMgF3

Abstract The location of the 5d-energy levels of Ce 3+ and Pr 3+ in the cubic perovskite KMgF 3 and in the distorted perovskite NaMgF 3 was determined from spectroscopic studies in the vacuum ultraviolet. It is established that Ce 3+ and Pr 3+ ions both occupy the same site in each host: K + sites for KMgF 3 and Na + sites for NaMgF 3 . The small crystal field splitting and the small value of the centroid shift of the 4f n −1 5d-configuration yield a relatively high energy for the lowest 5d state of both Ce 3+ and Pr 3+ . The lowest 5d state of Pr 3+ in both hosts is found at energy higher than the 4f 2 1 S 0 state, enabling the photon cascade emission to occur.