Hot band spectroscopy of CCO in the C–O stretching region: The (ν1 + 2ν3) − 2ν3 and (2ν1 + ν3) − (ν1 + ν3) bands

Two C–O stretching hot bands, (ν1 + 2ν3) − 2ν3 and (2ν1 + ν3) − (ν1 + ν3), of the CCO radical in the ground electronic state were measured. These hot bands are red shifted by approximately 70 cm−1 compared to the C–O stretching fundamental. CCO was produced in a discharge through a flowing mixture of carbon suboxide and helium. The spectra were recorded using a diode laser spectrometer. The band origins were determined to be 1904.32512(62) and 1902.69130(56) cm−1 for (ν1 + 2ν3) − 2ν3 and (2ν1 + ν3) − (ν1 + ν3), respectively. The measurements in this band together with previously reported frequencies in the C–C and C–O stretching regions were analysed to determine harmonic frequencies and anharmonicity constants.