The Rotation-Vibration Spectrum of Methyl Cyanide in the Region 1.6μ—20μ

Abstract

The infrared spectra of gaseous and liquid CH3CN have been investigated in the region 1.6μ—20μ with a Perkin-Elmer spectrometer using LiF, NaCl, and KBr prisms. The parallel type bands show, in general, a sharp Q branch and broad but more intense P and R branches. The perpendicular type bands are well resolved and show the expected intensity alternation ``strong, weak, weak, strong . . .'' of the subbands (Q branches). All the fundamentals, except ν8(e), which is beyond the region investigated, have been definitely established and vibrational assignments have been made for all the observed bands. Values for the rotational constants from microwave data have been used to obtain the Coriolis interaction constants,ζi, from the observed separations of the subbands of the ⊥ bands. The following values have been obtained: ζ5=0.10, ζ6=−0.44, and ζ7=0.41.