The first high-resolution infrared study of diazirinone, N2CO: Analysis of the Fermi-coupled ν 1 and 2ν 5 bands

Abstract: The first validated detection of the elusive diazirinone molecule (N2CO) in the gas phase was performed using high-resolution infrared spectra recorded in the 1810–2100cm−1 region. The ν 1 and 2ν 5 bands were identified at 2043.8 and 1863.3cm−1 close to the ab initio prediction [X.Q. Zeng, H. Beckers, H. Willner, J.F. Stanton, Angew. Chem. Int. Ed. 50 (2011) 1720–1723]. For these two bands, the individual lines exhibit a (2:1) intensity alternation, confirming a three membered ring structure (C2V symmetry) for N2CO. The major output of the ν 1 and 2ν 5 bands analysis is the first experimental determination of the ground-state rotational constants of cyclic N2CO. The observed intensity pattern of the ν 1 and 2ν 5 bands is in agreement with the existence of a strong Fermi resonance coupling the 11 and 52 energy levels. [Copyright &y& Elsevier]