Near-infrared Rayleigh scattering of SF6.

Cavity ring-down measurements have been performed on sulphur hexafluoride, in order to determine the extinction in the pressure range from 0 to 20 bar at 20°C (293 K), by using a tunable continuous wave distributed feedback diode laser emitting around 1180 nm. The cavity loss rate has been found to have both a linear dependence and a quadratic dependence on the gas density. While the linear component has been identified with the Rayleigh scattering, the quadratic component is likely due to collision-induced processes. The Rayleigh scattering cross section at 1180 nm has been determined as (1.25 ± 0.18) × 10-27 cm2 and has been compared with Rayleigh scattering cross sections measured in the deep-ultraviolet and visible spectral region.