Effect of Helium on the Raman Spectrum of Methane in the 2500-3300 cm-1 Range

The peak positions and halfwidths of the Q-branch of the nu(1) band and the ratios of intensities of the Q-branches of nu(3) and 2 nu(2) bands of methane are measured in a methane-helium mixture at different pressures and concentrations. An empirical model is developed for estimation of the He concentration in a methane-containing medium from measurements of the above parameters. The error in the He concentration is found to be less than 1% when using the nu(1) band halfwidth. The paths of improvement of this technique and enhancement of its accuracy are considered.

Automated summary

The study measured the spectral parameters of methane in different pressures and concentrations, and developed an empirical model for estimating the concentration of helium in a mixture, with an error of less than 1%. Paths for improvement of the technique and enhancement of its accuracy are considered.