Deep-UV Rayleigh scattering of N2, CH4 and SF6

Rayleigh scattering room temperature cross-section values of N2, CH4 and SF6 have been obtained between 198 and 270 nm by combining cavity ring-down spectroscopy (CRDS) and pressure ramp measurements. The experimental data have been fitted to a functional representation, describing the 1/4 like behaviour of the Rayleigh scattering cross section over a wide wavelength range. The resulting values are compared with numerical predictions, based on refractive indices and molecular anisotropy data available in the literature. From this, values of molecular volume polarizability vol and depolarization ratios are derived. It is found that the optical extinction for all three gases is governed by Rayleigh scattering for wavelengths down to 200 nm. No absorption onsets in the specified deep-UV region have been observed