1Y. Morino, J. Nakamura and S. Yamamoto, J. Mol. Spectroscopy 22, 34 (1967).Author Institution: Molecular Spectroscopy Laboratory, Department of Chemistry, University of MinnesotaThe infrared spectrum of ν5​ of methyl iodide has been observed with a resolution of about 0.03cm−1. The spectrum is complicated by some perturbations. A Fermi resonance with (ν3​+ν6​) which was observed by Morino, ct al.1 has been confirmed. In addition, other rotational perturbations have been observed