Non-Lorentzian hole profiles in organic glasses caused by a distribution of optical line widths

Using the optical hole burning technique, a non-lorentzian line profile was detected in the optical absorption spectra of chromophore molecules embedd ed in polymers and other organic glasses. The origin of the non-lorentzian hole profiles is a dispersion of interaction of chromophore molecules with two-level systems. This dispersion leads to a broad distribution of the abs orption line widths of the individual chromophore molecules. The width of t he distribution depends on temperature. Its maximal contribution to the exp erimental line width occurs at temperatures between 3 and 7 K, whereas it b ecomes less pronounced at higher and lower temperatures. As the main source of this distribution a dispersion of the TLS-chromophore interaction could be identified. (C) 2001 Elsevier Science B.V. All rights reserved.