High-Resolution Fourier Transform Infrared Spectroscopy of Vinyl Alcohol: Rotational Analysis of the ν13 CH2 Wagging Fundamental at 817 cm−1

The first high-resolution infrared spectra of the unstable molecule vinyl alcohol are reported. The spectra have been obtained using a new precursor, 2-chloroethanol, which when pyrolyzed at 1050°C gives strong infrared spectra of vinyl alcohol free of interfering hydrocarbon absorption bands. In this work, we have analyzed the strong ν13 fundamental at 817 cm−1 and substantially improved the ground state rotational constants by a simultaneous fitting of previous microwave data and a large number of infrared combination differences. The 131 upper state was found to be perturbed by the 152 “dark” state at 775.7 cm−1, and a complete analysis of the perturbed rotational structure has been achieved using an interacting two-state model. Further small perturbations at high Ka and J have been identified as interactions with the ν10 and ν12 fundamentals at 948 and 960 cm−1, respectively.