Concentration-dependent depolarized Raman spectra of HCl and DCl in solution in liquid carbon dioxide

The depolarized component of Paman scattering by pure liquid HCl and DCl and of solutions of these acid halides in liquid CO₂ are reported. At room temperature the band contours show no S branch intensity in pure acid halide liquid, but in solution in liquid CO₂ and S branch is increasingly evident with increasing CO₂ concentration. The frequency shifts are a function of the dielectric constant and refractive index of the solution. Reorientational correlation functions calculated from the anisotropic scattering decay more slowly in the first few tens of femtoseconds than predicted for monomeric acid halides, suggesting contribution to the composite correlation function by species of larger moments of inertia but vibrational frequencies identical with those of the monomers.