The properties of zero-phonon lines (ZPLs) for individual dibenzo-anthanthrene (DBATT) molecules in solid Xe have been studied. Systematic differences in the widths of ZPLs for molecules occupying different matrix sites were observed. For the majority of samples a monotonic increase of the average linewidth with temperature was found and satisfactorily described within a model, which combined (i) the line broadening caused by the interaction with two-level systems and (ii) dephasing due to the couplin with a local mode. For about 30% of studied samples, however, a surprisingly flat dependence of ZPL width on temperature was found. (C) 2002 Elsevier Science B.V. All rights reserved.