Knowledge Bank

High resolution absorption spectra of the $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma \to 2\Sigma$ CN violet system have been taken during the flash photolysis of BrCN vapor in excess argon. Accurate measurements of the $\Delta v=0$ and $-1$ sequences have been made and molecular constants derived for the $0\backslash leq\; v^\{\backslash prime\}^\{\backslash prime\}\backslash leq\; 6$ and $0\le v\prime \le 7$ levels. The results suggest that certain experimental modifications would allow the difficult CN “tail band” spectra (7 $\backslash leq\; v^\{\backslash prime\}^\{\backslash prime\}\backslash leq\; 12$ to be observed and rotationally analyzed.