FORCED RAYLEIGH-SCATTERING

Forced Rayleigh scattering (FRS) is a light scattering technique used to investigate light-induced grating structures that decay in a relaxational or almost relaxational manner. Such gratings can be created by interference and absorption of two pump beams and probed by a third beam, usually of different frequency. They may consist of spatially varying excited state populations with picosecond lifetimes or of long-lived variations in temperature, composition, and/or density. Forced Rayleigh scattering provides high sensitivity with respect to the amplitude and dynamics of such gratings and allows investigations not accessible by classical scattering techniques. The principles, techniques, and applications of FRS are reviewed.