Electronic energy-level structure and correlation crystal-field effects of Er3+ in Cs3Lu2Br9

Abstract
Single crystals of Cs3Lu2Br9:1% Er3+ were grown using the Bridgman technique. From highly resolved polarized absorption and luminescence measurements at 15 and 4.2 K, respectively, 101 crystal‐field levels from 27 different 2S+1LJ(4f11) multiplets of Er3+ in C3v symmetry were assigned. A Hamiltonian including 16 atomic and 6 crystal‐field parameters was fitted to a set of 87 crystal‐field levels and gave a rms standard deviation of 23.84 cm−1. Inclusion of one freely varying correlation crystal‐field (CCF) parameter lowered the overall rms standard deviation to 19.25 cm−1 and provided a dramatic improvement of the calculated crystal‐field splittings of specific CCF‐sensitive J multiplets.