HIGH-TEMPERATURE RAMAN SPECTROSCOPIC STUDY OF H2O-CO2-CH4 MIXTURES IN SYNTHETIC FLUID INCLUSIONS: FIRST INSIGHTS ON MOLECULAR INTERACTIONS AND ANALYTICAL IMPLICATIONS

Abstract

Raman spectra of fluids of the CO2-CH4-H2O systems contained in synthetic fluid inclusions have been obtained above the homogenization temperature to 500°C. Spectra of the CO2 and CH4 gases do not vary along the portion of the studied isochore, whereas they do for the symmetric stretching band of water. The spectra clearly show that molecular interactions are stronger between CO2 and H2O molecules than between CH4 and H2O molecules. Gas molecules decrease the signature of hydrogen bonding in the Raman spectrum of water. For water-rich fluids, the ratio of Raman scattering cross-section of CH4 and H2O does not vary to a wide extent, showing that the calibration of this ratio is feasible.