Soret Effect In Periodic Forced Rayleigh-scattering

In Forced Rayleigh Scattering of mixtures or suspensions the temperature grating generate, by Soret effect concentration gratings that may be very important since they produce both a phase and an amplitude grating superimposed on the principal one. We give an esplicit expression for the diffracted signal as a function of the driving parameters and of the material properties. Fundamental differential equation describing the temperature and concentration profiles are introduced and solved for a sinusoidal modulation of the pump beams and hence the far field diffraction pattern is computed by means of the Fraunhofer integral.