4f8-4f8 Ultraviolet absorption spectrum of Cs2NaTbCl6

► One-photon absorption (OPA) spectrum of Cs2NaTbCl6 recorded at 15 and 35 K. ► Detailed assignments given and electronic levels deduced. ► Selection rules for OPA very different from those for two-photon excitation (TPE). ► Comparison of results from OPA and TPE made. ► Good agreement.