Study of thermally induced light scattering in a relaxing fluid

Abstract

After recalling briefly the equations of motion for longitudinal excitations in a singly relaxing fluid, we calculate the damping constants and amplitudes of the Rayleigh and Mountain modes for the experimental situation in which a thermal grating has been induced in the fluid by a short and intense light pulse. We then present preliminary experimental results obtained in glycerol which agree qualitatively with the theoretical discussion. We derive from the data that the dispersion of the specific heat is probably quite small in glycerol