Knowledge Bank

The fine structure and hyperfine coupling constants were determined by an analysis of the microwave spectrum of the $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CN(X2\Sigma +),v=3-10$ levels. For example, those for the v=10 level were determined as follows (in MHz): B=51385.864[10], D=0.19606 (fixed), Y=156.777114), b=$-25.841(66)$, c=60.70(21), and eQq=$-0.171(68)$, where values in parentheses denote the standard errors. The analysis of the spin-rotation constants, together with the reported values for the $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CN(X2\Sigma +),v=0-9$ $levels,1$ showed that the second-order perturbation approximation was insufficient for the $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CN(X2\Sigma +),v=5-10$ levels. The electronic structure of the $CN(X2\Sigma +)$ state was studied on the basis of an analysis of the vibrational dependence of the hyperfine constants, where the free atom comparison method was found to be insufficient.