Knowledge Bank

An unusual spin related effect was observed in the l-type doubling of the $(0,11,0)-(0,11,0)$ band of $B2\Sigma +-X2\Sigma +$ system of SrOH. The data were found to fit the usual formulas for l-type doubling with the inclusion of two different spin rotation constants for the $B2\Sigma +$ state, $\gamma (+)$ and $\gamma (-)$, for the plus and minus parity levels respectively. Only the difference, $\gamma (+)-\gamma (-)$ could be determined from the fit and was found to be - $1.34\times 10-3(5)$ $cm-1$. The parameter $\gamma (+)-\gamma (-)$ is attributed to the simultaneous interaction of the two $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma 1/2$ vibronic states from the Renner-Teller split $(0,11,0)$ mode of the $A2\Pi$ state with the $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi$; vibronic state from the $(0.11,0)$ mode of the $B2\Sigma +$ state. A second order perturbation calculation was performed which included the Renner-Teller and spin-orbit interaction in the $A2\Pi$ state. From this calculation the Renner-Teller parameter was found to be $\epsilon \omega 2\sim 14$ $cm-1$. A discussion of this result to other triatomic molecules will be presented.