Pressure dependence of peak positions, half widths, and peak intensities of methane Raman bands ( ν 2 , 2 ν 4 , ν 1 , ν 3 , and 2 ν 2 )

Results of investigation of changing peak positions, half widths, and peak intensities of Q‐branches of the ν 2 , 2 ν 4 , ν 1 , ν 3 , and 2 ν 2 methane Raman bands are presented at pressures in the range 1–55 bar and а temperature of 298 K. The peak position of the ν 2 band remains practically unchanged, and peak positions of all other bands, by analogy with the ν 1 band, are shifted toward lower wavenumbers with pressure increase. It is demonstrated that the peak intensity ratio of any pair of the previously enumerated bands (except the pair of 2 ν 4 and 2 ν 2 ) is sensitive to pressure changes. When pressure increases, the decreased peak intensities of Q‐branches of depolarized ν 2 and ν 3 bands are caused by broadening of their rotational–vibrational lines, and the increased peak intensities of Q‐branches of the 2 ν 4 and 2 ν 2 bands are most likely caused by their increased interaction with the ν 1 and ν 3 bands. A set of data obtained will be useful for the Raman analysis of natural gas and can also be used for determination of the pressure of methane‐containing media. Copyright © 2017 John Wiley & Sons, Ltd.