Density effects on collision-induced spectra in fluids

Abstract

Selected results of recent Rayleigh and Raman scattering experiments on fluid N₂O and O₂ at high pressure are reviewed in order to illustrate the essential role of volume effects on collision-induced spectra in fluids. The depolarized Raman ν₁(1285 cm^–1) band and the depolarized Rayleigh lineshape were measured in fluid N₂O in the pressure range 8–3000 bar and over the temperature range 298–373 K. Rotational, collision-induced and cross-term contributions to the bandshapes and the second moments are discussed. The collision-induced effects on the depolarized Rayleigh scattering of fluid O₂ were measured at 300 K in the pressure range 20–3000 bar. The spectral moments M(0), M(2), M(4) and M(6) are calculated and their density behaviour is discussed in terms of the various contributions arising from rotational, collision-induced and cross terms.