Interaction-induced translational Raman scattering in dense krypton gas: Evidence of irreducible many-body effects

Depolarized interaction-induced light-scattering (DILS) spectra of dense gaseous krypton have been measured at room temperature (297 K) in the pressure range 10-270 bars. The absolute values of the integrated intensity and the second spectral moment have been evaluated, at each density, from the measured spectra, by means of a calibration procedure which makes use of a mixture containing a small fraction of molecular hydrogen, whose rotational Raman lines are used as an intensity standard. Monte Carlo computer simulation has been used to evaluate the first two even spectral moments at various densities and room temperature. The simulation was performed by use of the pairwise-additive potential and polarizability. The pair potential was the one given by R. A. Aziz [Mol. Phys. 38, 177 (1979)] while models for the pair-polarizability anisotropy were derived from the low-density collisional spectrum. The comparison between theory and experiment suggests that the second spectral moment is affected by irreducible many-body terms. It is suggested that, in addition to neutron scattering, DILS can be used as an experimental tool to probe irreducible many-body properties.