High-Resolution Infrared Spectra of the ν1 Fundamental Bands of Mono-Substituted 13C Propyne Isotopologues.

Abstract

We present a combined experimental and ab initio study on the jet-cooled high-resolution infrared spectra of the ν1 (acetylenic stretch) fundamental band for three isotopologues of propyne: 13CH312C≡12CH, 12CH313C≡12CH, and 12CH312C≡13CH. The experimental spectra are recorded in natural abundance using a continuous supersonic expansion of regular propyne diluted in argon and helium, in combination with continuous wave cavity ring-down spectroscopy (cw-CRDS). The fully rotationally resolved K' = 0 and 1 subbands of all three monosubstituted 13C isotopologues have been measured near 3330 cm-1, and their spectroscopic analysis is presented here for the first time. The assignment of the bands and perturbation analysis are assisted by high level ab initio calculations at the CCSD(T) level of theory, from which vibrational frequencies, rotational constants, and Fermi resonances are predicted for each isotopologue.