THE INFRARED-SPECTRUM OF METHYL CYANIDE BETWEEN 850 AND 1150 CM(-1) - ANALYSIS OF THE NU(4)-BAND, NU(7)-BAND, AND 3-NU(8)1-BAND WITH RESONANCES

The high-resolution infrared spectrum of CH3CN in the spectral region 850-1150 cm-1 has been studied with a resolution of 0.0035 cm-1 using a Fourier transform spectrometer. More than 4000 lines belonging to the fundamental bands ν4 and ν7 and to the overtone 3ν18 have been assigned. The coupled band system formed by the fundamentals ν4 and ν7 and the various overtones of the ν8 band have been analyzed by taking into account the Fermi resonances ν4/3ν38, ν7/3ν18 and ν7/2ν28. Furthermore, the Coriolis interaction ν4/ν7 and a number of l-type resonances are included in the calculations. As a result, the molecular constants for the states |v4 = 1〉, |v7 = 1, l7 = ±1〉, |v8 = 3, l8 = ±1〉, and |v8 = 3, l8 = ±3〉 as well as the resonance parameters describing the interactions between the studied energy levels have been obtained. © 1993 Academic Press, Inc.