The A2Π-X2Σ+ transition of SrCl: Rotational analysis and deperturbation

The SrCl A2Π-X2Σ+ system has been investigated using Doppler-free laser spectroscopy. Large parts of the (0, 0), (1, 1), and (2, 2) vibrational bands were recorded and rotationally analyzed. Microwave labeling helped to assign the complex spectra. The optical data were combined with the results of independent microwave measurements of the X2Σ+ state in a weighted least-squares fit in order to derive highly precise rotational constants of the A2Π state. Local perturbations were observed which are due to an A2Π 1 2 ∼ A2Π 3 2, Δv = 1 interaction. An additional weak perturbation is caused by an avoided crossing with the B2Σ+ state. A deperturbation analysis was applied and deperturbed A- and B-state constants as well as perturbation matrix elements are given.