Analytical fitting of temperature-dependent spin-flip transitions in absorption spectra of Cr3+-doped silicate glasses

Abstract Temperature-dependent optical absorption spectra have been recorded for Cr 3+ doped silicate glasses between 10 K and 773 K. Due to the intermediate ligand field strength of the Cr 3+ coordination environment, overlap of the lowest-energy spin-allowed 4 A 2  →  4 T 2 band and the two spin-forbidden transitions to the 2 E and 2 T 1 states at approximately 650 nm results in interference dips. An analytical model equation is fitted to the spectra and electronic structure parameters extracted. This represents the first time that variations of these parameters with temperature are obtained over a large temperature range, revealing characteristics of all three overlapping d-d transitions.