Knowledge Bank

We will report on Zeeman quantum beat studies of rovibronic levels in the $A2\Sigma +$ state of the hydroxyl and hydroxyl-d radicals. For each system the data extends to the onset of predissociation induced via spin-orbit coupling with a repulsive $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}\Sigma -$ state, which occurs for OH at $v=2$ and for OD at $v=3$. Our study focused on identifying direct spectroscopic signatures of this coupling as revealed in the weak field Lande g-factors. For OD, we were also able to determine the excited state hyperfine parameters, which are a sensitive probe of the excited state electronic structure, and trends in these parameters will be discussed.