The first high-resolution infrared study of diazirinone, N2CO: Analysis of the Fermi-coupled ν1 and 2ν5 bands

► First validated detection of the elusive diazirinone molecule (N2CO) in the gas phase. ► High-resolution FTIR spectra at 5 μm. ► ν1 and 2ν5 bands. ► C2V symmetry proved by (2:1) intensity alternation. ► Confirmation of ab initio predictions.