Fano antiresonances of Cr 3+ in alkaline disilicate glasses

Abstract

This work is devoted to a study of the features of the long-wavelength 4A 2→ 4T 2 absorption band of Cr 3+ ions in alkaline disilicate glasses. These features result from interaction of the 2E and 2T 1 sharp levels with the vibrationally broadened 4T 2 quasicontinuum via spin-orbit coupling and have been analysed in the frame of the Fano antiresonances model. The anti resonance profiles have been obtained from the ratio of the observed absorption spectra to the background spectra, the latter consisting of a single- or double-Gaussian function. The four fitted parameters involved in this model give information about the fraction of the quasicontinuum which takes part in the interference processes, the lineshape profile of the antiresonance, the width of the sharp level and its shift due to interaction with the quasicontinuum. These parameters have been calculated for Li, Na, and K disilicate glasses in the temperature range from 12 to 300 K.