Abstract

Since the early 1960s, light scattering spectroscopy has been applied extensively to condensed matter research. A considerable amount of microscopic information on liquid and crystalline solid state dynamics has been revealed. Recently, progress has slowed due mainly to the limitations inherent in conventional light scattering techniques for probing low frequency fluctuations in condensed phase materials. These limitations are well known: (1) the interference of parasitic scattering and quasielastic scattering can totally obscure low frequency dynamic modes of interest; (2) due to lack of spectral resolution in Bril- louin scattering below 1 GHz and of sensitivity in photon correlation (and excess attenuation in ultrasonic techniques) above 1 MHz, the frequency range between megahertz and gigahertz is not easily accessible.

© 1990 Optical Society of America