The rotational structures of the 0,0 violet and the 9,4 red CN bands, developed by CH${\mathrm{Cl}}_3$ in active nitrogen, are measured on plates from the first and second orders of a 30-ft. grating. The rotational constants of the $b^2\Sigma ,v=0\mathrm{}$ and the $a^2\Sigma ,v=4\mathrm{}$ states are in good agreement with the previously published values; those for the $v=9^2\Pi$ state are $B_{}^{\prime }{}_9{}^{}=1.5312\mathrm{}\pm 0.0008$ ${\mathrm{cm}}^{-1\mathrm{}}$, $D_{}^{\prime }{}_9{}^{}=7.408\mathrm{}\pm 0.002\times {10}^{-6\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$. The A-doubling in this state, except for four perturbations, can be represented by use of the constants $p_0=+0.01597\mathrm{}$ and $q_0=-0.00080\mathrm{}$. The value ${\gamma }^{\prime }=+0.021\mathrm{}$ is determined for the spin doubling in the $b^2\Sigma ,v=0\mathrm{}$ state. Four perturbations are found at $K=4,7,11, \mathrm{and} 15$ for $b^2\Sigma$; extra $P$ and $R$ lines separated from the main lines by $\Delta \nu =-0.352\mathrm{} {\mathrm{cm}}^{-1\mathrm{}},+0.938\mathrm{} {\mathrm{cm}}^{-1\mathrm{}},+1.177\mathrm{} {\mathrm{cm}}^{-1\mathrm{}}, \mathrm{and} +1.212\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$, respectively, appear in both the 0,0 and 0,1 bands of the violet system. In the red system, shifts of the right amount and direction in the lines $Q_1\left[3\mathrm{}\frac{1}{2}\right]$, $R_1\left[7\mathrm{}\frac{1}{2}\right]$, $P_1\left[7\mathrm{}\frac{1}{2}\right]$, $R_2\left[10\mathrm{}\frac{1}{2}\right]$, $P_2\left[10\mathrm{}\frac{1}{2}\right]$, and $Q_2\left[15\mathrm{}\frac{1}{2}\right]$ confirm the assumption that rotational levels of ${}_{}{}^2{}_{}{}^{}\Pi ,v=9\mathrm{}$, perturb those of $b^2\Sigma ,v=0\mathrm{}$, and that the perturbations occur for the $K$ and $J$ values indicated. (Brackets denote upper state $J$.) The values of the perturbation matrix elements are obtained for the various levels. Some anomalies of the $R$ branch band lines in the range 23-29 of $K^{\prime }$ values in the 0,0 violet band are mentioned.

The mechanism responsible for the enhancements of the main and extra lines of the 0,0 violet band is discussed. Collisions involving interstate transfer (${}_{}{}^2{}_{}{}^{}\Pi \to a^2\Sigma$) evidently occur, or are enhanced, at each perturbed level; and rapid redistribution of molecules among rotational levels by collisions must also occur. Where spin doublets are resolvable in the violet bands, rotational redistribution occurs without change of spin direction.

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