Simulation of ν2 Raman band of methane as a function of pressure

• Published in: Journal of Raman spectroscopy Vol. 53; no. 3; pp. 654 - 663
• Main Authors: Tanichev, Aleksandr S., Petrov, Dmitry V.
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.03.2022
• Subjects: Mathematical analysis; Methane; Natural gas; Pressure; pressure broadening; Pressure effects; Raman spectroscopy; Spectra; spectra simulation; Spectral resolution; Spectrum analysis
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.6145

The in situ analysis of natural gas is one of the most promising applications of Raman spectroscopy. It is necessary to take into account the pressure effect on the spectrum of methane to improve the accuracy of this technique. This study aimed to develop and verify two methods for simulating the ν2 Raman band of methane at any spectral resolution and pressure. The first method was based on the use of the spectroscopic parameters of each single line (position, intensity, broadening, and shift coefficient). The second one was based on the use of the spectral profiles, each of which replaces a group of lines. The data required for the implementation of each method are presented in this work. A comparison of the calculated and measured spectra with a resolution of ~0.5 and ~7 cm−1 was performed. It was shown that the differences do not exceed 5% for each method in the range of 1–60 atm. In this study, the method of simulating the Raman ν2 band of methane at various pressures and any spectrometer resolution > 0.5 cm−1 was considered. Using the fitting procedure of the measured spectra, two sets of spectral parameters were obtained for simulation. The differences between the calculated and experimental spectra do not exceed 5% in the range of 1–60 atm.