High resolution infrared analyses of fundamentals and overtones in isotopic ketenes

Abstract

Rovibrational structure in the ν 5, ν 6, ν 7, ν 8 fundamentals and 2ν 5, 2ν 6 overtones in each of H 2 12C 12CO, H 2 12C 13CO, H 2 13C 12CO has been assigned and analysed. The effects of Fermi resonance between ν 7 and ν 2+ν 8 are corrected for, and a set of accurate unperturbed vibrational frequencies and 13C isotopic frequency shifts therefrom is obtained. The changing effects of the major Coriolis interactions involving the out-of-plane fundamentals, ν 5 and ν 6, are manifest in varying isotopic displacements of equivalent Q branch structures between the isotopic species studied, from which accurate isotopic vibrational shifts are obtained. Variable anharmonicity constants associated with the vibration frequencies of 2ν 5 and 2ν 6 give evidence of major Fermi resonance interactions between both overtones and the ν 4 fundamental, which they straddle.