Electronic and vibrational levels of the photochromic Mn in sillenties

Abstract Visible and high resolution FTIR spectroscopy (at 9 K) and MCD (at 1.4 K) measurements are applied to study the valency and the coordination of Mn in photorefractive and Photochromic sillenites (BSO, BGO, BTO and Mixed BSO—BMnO) single crystals. Vibrational transitions of Mn5+ in T d symmetry, due to excitation of an F mode, its overtone and combination with an A mode are detected. The crystal field spectra and MCD results strongly support the d2 configuration for Mn in T d symmetry. Vibronic replicas of the 3 A 2→1 E electronic transition, in which ones or two vibrational modes are also excited, are reported.