The rotational spectrum of BiO radical in its X12Î 1/2 and X22Î 3/2 states

Rotational spectra have been observed for BiO produced in a DC discharge through a low pressure mixture of O2, Ar, and Bi vapor. Because of the highly non-thermal distribution of states, it has been possible to observe spectra arising from the X12Π1/2 level up to v = 9 and for the X22Π3/2 level up to v = 5 near 10 538 cm−1. Precise rotational and hyperfine parameters have been determined for the observed states. By using available near infrared (NIR) data in a merged fit, the 0-0 and 1-1 fine structure intervals have been more precisely determined. Although the quality of the fit is very good, the interpretation of the hyperfine constants is complicated by relativistic effects and the interaction of the X2 state with A14Π3/2 state. The magnetic and quadrupole coupling constants will be compared with those of the Bi atom and related molecules.