Modified Scattering by Hydrogen Halides

Raman lines of the gases of HCl (previously measured by R. W. Wood), of HBr and HI and of the liquids of HCl and HBr have been measured. The Raman shifts of the lines of HCl and HBr gases agree with the infrared bands. The Raman shift of HI, 2233 cm^-1, does not agree with the infrared value and is considered the more accurate determination of the (0, 1) vibrational transition for HI. Intensities of scattering are in the reverse order of intensities of absorption, as might be expected from the Hill-Kemble theory of scattering by diatomic molecules of gases. The Raman lines scattered by the liquids show a different appearance from the lines scattered by the gases and their Raman shifts are smaller. The differences in the shifts are much too large to be attributed to a Lorentz-Lorenz force and are evidence of molecular interactions of a purely quantum mechanical nature, as discussed by Breit and Salant.