Pressure and Density Dependence of the CH 4 and N 2 Raman Lines in an Equimolar CH 4 /N 2 Gas Mixture

Abstract

Experiments have been performed to determine the variations of the peak area for the CH₄ and N₂ Raman lines along with their frequency shift and broadening, as a function of pressure and density, in the case of an equimolar CH₄/N₂ gas mixture. A comparison is made between the relative values of the Raman scattering cross sections for the two species and the values of the internal field term, versus density of the mixture, showing that the density dependences of these physical quantities become more dissimilar as density increases. Moreover, the ratio of the peak areas for the CH₄ and N₂ Raman lines is found to be constant in the entire pressure range used. From a practical point of view, these results for gas mixtures could be useful in quantitative analysis of fluid inclusions in rocks.