Measurement of Rayleigh ratio for several pure liquids using a laser and monitored photon counting

The Rayleigh ratios of several liquids have been measured using a He–Ne laser and established techniques of high-speed, monitored photon counting with dead-time corrections and low dark rate. A simple well-defined geometry at 90° scattering angle was used and the following values of R90,u (× 106) at 633 nm and 22°C were obtained: carbon disulfide 42.64, benzene 8.51, toluene 10.38, methanol 1.422, carbon tetrachloride 2.954, and water 0.494. Errors are estimated to be less than 2%. These values are in generally good agreement with other recent measurements at narrow angle at the same wavelength, but after scaling by the accepted formula would seem to be somewhat smaller than quoted values at shorter wavelengths.