Infrared Spectra of Gas-Phase 1- and 2‑Propenol Isomers

Fourier transform
infrared spectra of isolated 1-propenol and 2-propenol
in the gas-phase have been collected in the range of 900–3800
cm–1, and the absolute infrared absorption cross
sections reported for the first time. Both cis and trans isomers of 1-propenol were observed with the trans isomer in greater abundance. Syn and anti conformers of both 1- and 2-propenol were also observed,
with abundance consistent with thermal population. The FTIR spectrum
of the smaller ethenol (vinyl alcohol) was used as a benchmark for
our computational results. As a consequence, its spectrum has been
partially reassigned resulting in the first report of the anti-ethenol conformer. Electronic structure calculations
were used to support our experimental results and assign vibrational
modes for the most abundant isomers, syn-trans-1-propenol
and syn-2-propenol.