Abstract

The dynamics of small, highly polarizable molecules have been studied extensively by light scattering. We have shown that the time-resolved technique of Impulsive Stimulated Scattering (ISS) can offer distinct advantages over conventional frequency-domain light scattering.¹ In particular, ISS is well-suited to the measurement and characterization of low-frequency heavily-damped modes of molecular motion. Various theories of the liquid state predict such modes at high densities as a result of molecular caging effects. As the density of a liquid is increased, nearest neighbor distances decrease on average and the short-time dynamics of molecules are expected to be dominated by repulsive intermolecular interactions. A temperature-dependent study of the transient response of CS2 showed a weakly oscillatory signal suggestive of intermolecular vibration.² To further study intermolecular vibration in dense liquids we have combined femtosecond time resolution with diamond anvil cell technology to study the ultrafast dynamics of CS2 molecules at constant temperature as a function of pressure.

© 1990 Optical Society of America