Distribution of single-molecule line widths

Single molecule spectroscopy shows that line shapes of guest molecules in l ow-temperature disordered solids vary from one molecule to the other. We co nsider a single molecule in a host lattice interacting with randomly distri buted two level defects via a long range interaction. We investigate in det ail the dipolar interaction and calculate the probability density of varian ces for high and low densities of defects. (C) 1999 Published by Elsevier S cience B.V. All rights reserved.