Absolute Raman Scattering Cross-Section Measurement of the 992 cm^−1 Line of Benzene*

An accurate measurement has been made of the Raman scattering cross section of the 992 cm−1 line of benzene. Previous cross-section measurements were either made indirectly by comparison with the Rayleigh scattering cross section or by using a pulsed light source. In the present measurement the cross section was measured directly using a cw argon laser as the light source. The results give a peak differential cross section of 1.05(±0.08)×10−29 cm2 per molecule, per steradian, per wavenumber of linewidth, per plane of polarization for an incident light beam with a wavelength of 4880 Å, and a linewidth of 2.3 (±0.05) cm−1. Allowing for the wavelength dependence and the optical dispersion, our total cross section agrees to within 20% with two other results. The Raman scattering cross sections of other liquids have been measured by use of the 992 cm−1 line of benzene as a reference. These values, together with details of the absolute cross-section measurement, are presented.