THE ν2 RAMAN BAND OF METHANE

Abstract

The doubly degenerate ν₂ Raman band of methane was photographed at a gas pressure of 2 atm. with a reciprocal linear dispersion of 10.5 cm.⁻¹ per mm. An analysis of the O and S branches gave ν₀ = 1533.6, B₀ = 5.270, and B₁ = 5.392 cm.⁻¹. When the Raman data are combined with the infrared data of Burgess, Bell, and Nielsen, the effect of the Coriolis interaction of ν₂ with ν₄ is seen to be a splitting of the rotational levels of the upper vibrational state of ν₂ into two sets, each of which can be represented by an effective value of B₁. The Raman O, S and the infrared P (strong), Q, R (weak) transitions terminate in states with B₁ = 5.392 cm.⁻¹; the Raman P, Q, R and the infrared P (weak), R (strong) transitions terminate in states with B₁ = 5.322 cm.⁻¹.