Abstract

The dynamical properties of liquids may be probed in the time domain in two ways: either in the neat liquid by nonlinear scattering experiments, or else indirectly by studying the solvation dynamics of molecular probes [1,2]. In the latter case, optical excitation of a suitable dye molecule leads to a change in molecular dipole moment. As the surrounding solvent adjusts to a new equlibrium, solvent-solute interaction stabilizes the excited molecule, and this results in a red-shift of the fluorescence spectrum. Typical compounds for this purpose are coumarin or styryl dyes. However their use for ultrafast solvation dynamics is limited by a relatively large spectral width of fluorescence, or by the possibility of geometrical isomerisation. Furthermore, measurement requires fluorescence upconversion and spectral reconstruction which may be quite tedious.

© 1992 The Author(s)