Infrared diode laser spectroscopy of the ν1 fundamental and the ν1 + ν2 − ν2 sequence bands of the CCO radical

The infrared absorption spectrum of the CCO radical has been studied in an extension of the original observation of the CO stretching vibration by Yamada et al. [J. Chem. Phys. 84 (1985) 2573]. The CCO radical was generated using a flowing mixture of carbon suboxide and helium subjected to a hollow-cathode discharge. The spectral region between 1930–1990 cm−1 was probed using a tunable diode laser spectrometer. Transitions with N-values up to 40 were measured for the ν1 fundamental and ν1 + ν2 − ν2 sequence bands. Their analysis yielded band origins, rotational, centrifugal distortion, spin-spin interaction, and spin-orbit interaction parameters for the lower and upper vibrational states, and l-doubling parameters for the degenerate bending states ν2 = 1 and (ν1 = 1, ν2 = 1). In particular, the band origins for ν1 and ν1 + ν2 − ν2 were determined to be 1970.86332(41) cm−1 and 1960.13093(37) cm−1, respectively.