Knowledge Bank

The $A~2\Pi -X~2\Sigma +$ transition of BaOD has been rotationally analyzed using high-resolution laser excitation spectroscopy. BaOD molecules were synthesized in a Broida-type oven and detected using a single mode Ti:Sapphire laser. Measured rotational lines have been assigned, and rotational and fine structure parameters determined through a combined least-squares fit with the millimeter-wave pure rotational data of the $X~2\Sigma +$ state. A significantly different spin-orbit coupling constant from the corresponding value for BaOH was observed and attributed to global and local perturbations arising from vibrationally excited bands of the $A~\prime 2\Delta$ state. $\Lambda$-doubling constants for the $A~2\Pi$ state also showed poor agreement with the predictions of the pure precession model. To further understand the nature of the interactions between the $B~2\Sigma +$, $A~2\Pi$ and $A~\prime 2\Delta$ states of BaOH, a V-type optical-optical double resonance spectroscopy experiment was prepared to locate the lower-lying excited state levels. Preliminary results have yielded a band in close proximity on the lower wavenumber side of the $A~2\Pi 1/2$ spin component of BaOH with a relatively large $p$ value. Further results of this ongoing experiment will be presented.