THE RAMAN SPECTRUM OF METHANE

Abstract

The Raman spectrum of CH4 was obtained with a spectral resolution of ~0.3 cm−1, and rotational analyses of the ν and ν2 bands were carried out. The B0 values obtained from the ν2 and ν3 bands are 5.240 ± 0.002 and 5.2406 ± 0.0011 cm−1, respectively; the value of ν0 determined from the latter is 1.09403 ± 0.00016 Å. The rotational levels of the ν = 1 state of ν2 are double with B1 values of 5.313 and 5.379 cm−1. The rotational levels of the ν = 1 state of ν2 do not follow the theoretical formulae exactly; the deviations for the 13 branches observed can be expressed by using three different B1 values, 5.178, 5.195, and 5.212 cm−1. The value of ζ3 is 0.054. The band origins are: ν1 = 2916.7, ν2 = 1533.6, and ν3 = 3018.9 cm−1.