Knowledge Bank

Using the line positions measured by Sheasley and $Mathews,1$ we have reanalyzed the $A2\Sigma +$ - $X2\Pi$ emission spectrum of $H35$Cl$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$, $H37$C1$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$, $D35$C1$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ , and $D37$Cl$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$, employing the Hamiltonians and direct approach” described by Zare, Schmeltekopf, Harrop, and $Albritton,2$ The values for the spin orbit centrifugal distortion constant, $AD$, obtained in the present analysis have changed in both sign and magnitude from those obtained previously and now are approximately twice the values predicted by Veseth. The isotope ratio, $AD(DC1+)/AD(HCL+$) , previously $\cong 0.23$, and theoretically $\cong$ 0.51, was found to be $\cong 0.45$, We believe the remaining discrepancy In the magnitudes of our $AD$ values is caused by arbitrarily neglecting the $\Pi$ state spin-rotation constant, $\gamma$$\Pi$, and we have obtained values of this constant for several vibrational levels by fixing $AD$ to values calculated from the Coxon $relation.3$ The molecular constants for the $A2\Sigma +$ state are virtually the same as those obtained previously.