Raman Spectra of Nitrogen, Carbon Dioxide, and Hydrogen in a Methane Environment

Abstract

Changes in the Raman spectra of N₂, H₂, and CO₂ are studied in the range of 200–3800 cm^–1 depending on the concentration of surrounding CH₄ molecules at a fixed medium pressure of 25 atm and temperature of 300 K. It has been found that changes in the spectral characteristics of purely rotational H₂ lines in a CH₄ medium are negligible, while the Q-branches of the v₁/2v₂ Fermi dyad in СO₂ become narrower and wavenumbers of its high-frequency component and v₁ band of N₂ decrease. In addition, under these conditions, the ratio of intensities of the CO₂ Fermi dyad Q-branch varies in proportion to the concentration of surrounding molecules of CH₄. The obtained data will be used in diagnosing the composition of natural gas using Raman spectroscopy.