Fano antiresonances of Cr3+ in alkaline disilicate glasses

This work is devoted to a study of the features of the long-wavelength (4)A (2) --> T-4(2) absorption band of Cr3+ ions in alkaline disilicate glasses. These features result from interaction of the E-2 and T-2(1) sharp levels with the vibrationally broadened T-4(2) quasicontinuum via spin-orbit coupl ing and have been analysed in the frame of the Fano antiresonances model. T he anti resonance profiles have been obtained from the ratio of the observe d 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 ant iresonance, the width of the sharp level and its shift due to interaction w ith the quasicontinuum. These parameters have been calculated for Li, Na, a nd K disilicate glasses in the temperature range from 12 to 300 K. (C) 1999 Elsevier Science B.V. All rights reserved.