Spectroscopy and perturbation analysis of the A1π (v=0) state of 13 C16 O

Abstract

The lowest v = 0 level of the A1Π state of the 13C16O isotopologue of carbon monoxide has been reinvestigated with a variety of high-resolution spectroscopic techniques. The A1Π −X1Σ+(0, 0) band has been studied by vacuum-ultraviolet Fourier-transform absorption spectroscopy, using the SOLEIL synchrotron as a radiation source. Spectra were obtained under quasi-static gas conditions at liquid-nitrogen temperature, room temperature and at an elevated temperature of 900 K, with absolute accuracies of 0.01−0.03 cm−1. Two-photon Doppler-free laser spectroscopy has been applied to a limited number of transitions in the A1Π −X1Σ+(0, 0) band, under collision-free circumstances of a molecular beam, yielding an absolute accuracy of 0.002 cm−1. The third technique is high-resolution Fourier-transform emission spectroscopy in the visible region applied to the B1Σ+ −A1Π(0, 0) band in a gas discharge, at an absolute accuracy of up to 0.003 cm−1. With these methods, rotational levels of A1Π (0) could be studied in both parity components up to a rotational quantum number of J = 46. The frequencies of 397 transitions were used to analyse the perturbations between the A1Π(0) level by vibrational levels of the D1Δ, e3Σ−, d3Δ, and a′3Σ+ states.