Spectroscopy and perturbation analysis of the CO A(1)pi -X-1 sigma(+) (2,0), (3,0) and (4,0) bands
ABSTRACTThe (2,0) (3,0) and (4,0) bands of the A1Π −X1Σ+ system of 12C16O have been re-investigated by high-resolution vacuum ultraviolet absorption spectroscopy. A vacuum ultraviolet Fourier-transform spectrometer, illuminated by synchrotron radiation, was applied to record a jet-cooled spectrum, a room temperature static gas spectrum and a high-temperature (900 K) quasi-static gas spectrum, resulting in absolute accuracies of 0.01−0.02 cm−1 for the rotational line frequencies. Precise laser-based data were included in the analysis allowing for a highly accurate determination of band origins. Rotational levels up to J = 52 were observed. The data were used to perform an improved analysis of the perturbations in the A1Π, v = 2, v = 3 and v = 4 levels by vibrational levels of the D1Δ, I1Σ−, e3Σ−, d3Δ and a′3Σ+ states.