High-Resolution Infrared Spectroscopy and Analysis of the Methyl Group Stretching (ν1) of CH3NC

✍ Scribed by C. He; J. Pliva; C.M. Faust; M. Elshakre; L.P. Gold; R.A. Bernheim

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 584 KB
• Volume: 160
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1993.1195

✦ Synopsis

The rotational structure of the symmetric (\mathrm{C}-\mathrm{H}) stretching fundamental band (\nu_{1}) of methyl isocyanide has been revealed for the first time; 540 well-resolved spectral transitions were measured with a resolution of (0.004 \mathrm{~cm}^{-1}) using an interferometric spectrometer and were assigned to (\nu_{1}) lines with (K=0) to 9 and (J) up to 50 . The (\nu_{1}) levels are highly perturbed, exhibiting anomalous structure in most of the observed subbands. The origin of the stronger perturbations has been traced mainly to (x, y)-Coriolis interactions with the degenerate (\mathrm{C}-\mathrm{H}) stretch (v_{s}) and with the combinations (\nu_{2}+3 \nu_{8}^{71}) and (\nu_{4}+v_{6}^{71}+2 v_{8}^{ \pm 2}), to Fermi resonance with (2 v_{6}^{0}), and to a higher-order anharmonic resonance with another combination state, presumably (\nu_{2}+3 v_{\bar{B}}^{-3}). These interactions have been explicitly taken into account in a least-squares fit of the observed transitions, yielding spectroscopic constants for the (\nu_{1}) state. Estimates of the spectroscopic constants for the perturbing states together with their coupling constants with (v_{1}) are also reported. 1993 Academic Press, inc.