Raman Spectrum of Water Vapor in Methane Aleksandr S. Tanichev, Dmitry V. Petrov Journal of Raman Spectroscopy, 2025 Monitoring the humidity of natural gas (NG) during transportation through main pipelines is a critical task, as high pressures and low temperatures promote the undesirable formation of hydrates. Raman spectroscopy represents a promising non‐contact method for developing highly accurate humidity measurement instruments. However, the Raman spectrum of water vapor is sensitive to variations in external conditions typical of transported NG. These spectral changes must be taken into account to achieve high measurement accuracy. This paper presents the first investigation of the Raman spectrum of water vapor in gaseous methane, covering both vibrational bands (ν1 and ν3) and pure rotational lines of water. The methane‐broadening and shift coefficients of water spectral lines were measured. The magnitude of pressure‐broadening for anisotropic water lines in methane was found to be comparable to that induced by atmospheric air. The obtained results can be utilized to improve the accuracy of water vapor concentration retrieval from Raman spectra.
Helium Detection in Natural Gas Using Raman Spectroscopy Aleksandr S. Tanichev, Dmitry V. Petrov Applied Spectroscopy, 2025 Raman spectroscopy has great potential for quantitative analysis of natural gas. Helium is one of the components of natural gas and has a wide range of applications. It was believed that noble gases could not be detected using this technique due to the absence of their vibrational spectra. In this study, we demonstrated an approach to extracting the content of helium from the Raman spectrum of methane and carried out test measurements for the first time. The approach is based on the determination of changes in the ν1 band of methane caused by the influence of helium and other components. The necessary spectroscopic parameters characterizing the effect of methane (CH4), helium (He), nitrogen (N2), carbon dioxide (CO2), and ethane (C2H6) on the ν1 band of methane at a resolution of 0.35 cm−1 were obtained. The validation of the approach showed that the helium content in natural gas can be measured with an uncertainty of 1 mol% at a sample pressure of 50 bar. The measurement precision can be increased to 0.01 mol% by using a high-resolution spectrometer. The described method does not claim to replace helium detectors, but it can be considered a valuable addition to Raman gas analysis of natural gas in developing an all-in-one device. The possibilities for further improvement of the approach are also discussed.
Raman Gas Analyzer Based on a Multimode Diode Laser M. A. Kostenko, I. I. Matrosov, A. R. Zaripov, A. S. Tanichev, V. K. Volkov, S. D. Korkishko, D. V. Petrov Instruments and Experimental Techniques, 2024 Abstract The article presents the concept of gas analyzer based on Raman spectroscopy where a multimode blue diode laser is used as an excitation source. Methods for reducing the spectral width of the radiation of such a laser due to external feedback have been investigated. It has been shown that, when an optical scheme based on Fabry–Pero interferometer is used for this purpose, the resolution of the recorded Raman spectra can reach 8 cm–1. The performance of the developed Raman gas analyzer is presented and discussed. It was established that the achieved signal-to-noise ratio at the analysis time of 2 s allows detection of any type of molecule with concentration of >1%.
13CH4/12CH4 sensing using Raman spectroscopy Dmitry V. Petrov, Aleksandr S. Tanichev Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy, 2024 The paper presents a technique for measuring the concentration of <sup>13</sup>CH<sub>4</sub> in natural methane using Raman spectroscopy. The peak positions and the relative scattering cross-sections of the Q-branches for the most intense vibrational bands of <sup>13</sup>CH<sub>4</sub> are determined. Features of the <sup>13</sup>CH<sub>4</sub>/<sup>12</sup>CH<sub>4</sub> ratio measurement methods using Q-branches of the ν<sub>1</sub> and ν<sub>3</sub> bands were considered. It was shown that the <sup>13</sup>CH<sub>4</sub>/<sup>12</sup>CH<sub>4</sub> ratio can be determined by simulation of the ν<sub>3</sub> bands of these molecules without the use of experimental spectra. In our experiments the measurement error of δ<sup>13</sup>C value was 10 ‰ using the 100-s exposure spectrum at a gas pressure close to 1 atm recorded on the developed Raman spectrometer. In addition, the Raman spectra of alkanes (up to n-hexane) in the range of 2850-3050 cm<sup>-1</sup> at a resolution of 0.4 cm<sup>-1</sup> are presented, and their integrated intensities in the ranges of the characteristic bands of <sup>13</sup>CH<sub>4</sub> and <sup>12</sup>CH<sub>4</sub> are provided. The data obtained make it possible to expand the capabilities of Raman gas analyzers in the mud gas logging industry.
Temperature and Methane Pressure Effects on the Spectral Characteristics of the Raman Bands of n-Butane in the Range 300–1100 cm–1 A. S. Tanichev, D. V. Petrov, I. I. Matrosov, A. R. Zaripov Russian Journal of Physical Chemistry A, 2024 Abstract Changes in the spectral characteristics of the vibrational bands of n-butane have been studied in the spectral range 300–1100 cm–1 at a temperature varied from 285 to 365 K and a methane pressure varied in the range 2–40 atm. It was established that the enthalpy of the trans–gauche transition of n-butane in the gas phase is 657 ± 66 cal/mol. The methane pressure in the given range was found to have a negligible effect on the conformational equilibrium of n-butane. The impact of changes in the spectral characteristics of n‑butane on the accuracy of measuring the composition of natural gas using Raman spectroscopy was determined.
A simple model to simulate the Raman spectrum of methane in the range of 2800–3040 cm−1 Aleksandr S. Tanichev, Dmitry V. Petrov, Matvey A. Kostenko Journal of Raman Spectroscopy, 2023 Raman spectroscopy is a promising method to analyze natural gas. Measurement of hydrocarbon concentrations is required for quality control of this fuel. Despite the presence of intense characteristic peaks of hydrocarbons in the range of 2800–3040 cm−1, researchers avoid this region due to the overlap with a methane spectrum. This paper presents a simple method to simulate the Raman spectrum of methane in natural gas at different pressures and concentrations of nitrogen, carbon dioxide, and ethane. A detailed description of the algorithm and the empirical parameters necessary for the simulation are provided. The method can be used to improve the accuracy of the Raman gas analysis of natural gas and other methane‐bearing media.
Broadening of the ν2 Raman Band of CH4 by C3H8 and C4H10 Aleksandr S. Tanichev, Dmitry V. Petrov Molecules, 2023 Raman spectroscopy is a promising method for the analysis of natural gas. It is necessary to account for the broadening effects on spectral lines to improve measurement accuracy. In this study, the broadening coefficients for methane lines in the region of the ν2 band perturbed by propane, n-butane, and isobutane at room temperature were measured. We estimated the measurement errors of the concentration of oxygen and carbon dioxide in the case of neglecting the broadening effects on the methane spectrum by the pressure of C2–C6 alkanes. The obtained data are suited for the correct simulation of the methane spectrum in the hydrocarbon-bearing gases and can be used to improve the accuracy of the analysis of natural gas by Raman spectroscopy.
Development of Raman Gas Analyzers at IMCES SB RAS D. V. Petrov, I. I. Matrosov, A. S. Tanichev, M. A. Kostenko, A. R. Zaripov Atmospheric and Oceanic Optics, 2022 Gas analyzers on the basis of Raman spectroscopy designed at the Institute of Monitoring of Climatic and Ecological Systems, Siberian Branch, Russian Academy of Sciences, are described. Their capabilities and advantages are shown in measurements of the composition of fuel gases (natural, bio-, and synthesis gases) and atmospheric and exhaled air. The features of the analyzer operation and the techniques for increasing the measurement accuracy are discussed.
SHG in γ-Ga2S3 powder Yury M. Andreev, Valery A. Svetlichnyi, Alexander . Tanichev, Konstantin A. Kokh, Artem B. Kuznetsov, Gregory V. Lanskii, Dmitry Ezhov Proceedings of SPIE the International Society for Optical Engineering, 2018
