HIGH-RESOLUTION STUDY OF THE INFRARED BAND NU-8 OF CH3CN

The lowest fundamental band ν8 of CH3CN, around 365 cm-1, has been measured on a Bruker Fourier transform spectrometer at a resolution of 0.0035 cm-1. About 2000 lines have been assigned in 23 subbands. In the analysis the l(2, 2) resonance has been important. The standard deviation 0.16 × 10-3 cm-1 has been reached in the fit with 8 fixed nonzero ground state constants and 16 free parameters. A simultaneous analysis together with pure rotational lines from the literature has also been performed in order to get an even better set of molecular parameters. By combining this work and measurements of the ν7 + ν8 and ν7 + ν8 - ν8 bands it has been possible to determine the ground state constants A0 and D0 K. The very preliminary results, 5.27362 cm-1 and 94.2 × 10-6 cm-1, respectively, have been used in the analysis. © 1992.