Knowledge Bank

We report quantum beat studies of the energy dependence of the Zeeman parameters in the $A2\Sigma +$ state of OH and OD, and the nuclear hyperfine parameters of $OD(A2\Sigma +)$. In contrast to a previous study, we find that the sign and magnitude of the anisotropic g-factor $g\ell$ for $\nu \prime =0$ is consistent with that expected from Curl's relationship. However, at higher energies $g\ell$ changes sign, and possible explanations for this trend will be examined. The magnetic and electric quadrupole hyperfine constants were determined for $OD(A2\Sigma +,\nu \prime =0-3$), and the constants for $\nu \prime =2,3$ are reported here for the first time to our knowledge. The derived values are consistent with available ab initio calculations.