MOLECULAR ELECTRONIC SPECTRAL BROADENING IN LIQUIDS AND GLASSES

The magnitudes, time scales, and underlying mechanisms responsible for broadening the electronic spectra of molecules in liquid solutions an d glasses are reviewed. The emphasis is on experimental results from h ole-burning, single-molecule, photon echo, and resonance Raman and flu orescence studies. The influence of the time scale of the measurement in distinguishing between homogeneous broadening (electronic dephasing ) and inhomogeneous broadening is discussed, and the role of coupling of solvent phonons to the solute's electronic transition is stressed.