Laser spectroscopy of perturbed states of BaO in the region above 32 000 cm−1

Abstract

The excitation spectrum of BaO in the region above 32 000 cm −1 was investigated with a frequency-doubled pulsed dye laser. We have observed fully developed rotational structures of the C 1 Σ + - X 1 Σ + transition. The analysis of the vibrational states v ′ = 0 through 7 leads to a large number of perturbations. This spectroscopic information in combination with the observation and rotational analysis of transitions to several new electronic states allows a systematic summary, which gives more than eight electronic states in the investigated region. Besides the known states B , C , D and c , we find four new bound states, designated by E , F , G , and H . For all states molecular constants are given. The discussion of possible molecular electron configurations leads to classifications of the molecular electronic states. Our results on the vibrational levels v ′ = 0 to 3 are in reasonable agreement to the optical-optical double resonance work of R. A. Gottscho, P. S. Weiss, and R. W. Field [ J. Mol. Spectrosc. 82 , 283–309 (1980)], but show several new details.