Knowledge Bank

The violet $(B2\Sigma +-X2\Sigma +)$ and red $(A2\Pi 1,-X2\Sigma +$) systems of the CN molecule are produced in a jet-cooled corona excited supersonic expansion of helium using diazoacetonitrile or methyl azide as precursor molecules. The violet system of CN was also produced in a Cossart source with a trace of methane in argon. The spectra were recorded with McMath Fourier transform spectrometer of the National Solar Observatory. The results obtained for the violet system were recently $published1$. In the red system we observed 27 bands with $v\prime =8$ to 21 and $v\prime \prime =1$ to 11 in the range $16570-22760cm-1$ (LeBlanc bands). The wavenumber data of this system were fitted along with those of the violet system, infra-red (vibration-rotation) data, and microwave data and a total of 119 parameters were estimated in the global fit. These parameters were used to estimate the equilibrium molecular constants, to construct the RKR potential energy curves, and to calculate the FCFs for various bands of the A-X, B-A, and B-X systems of the CN molecule. In the same spectrum we also observed 10 bands with $v\prime =0$ to 3 and $v\prime \prime =0$ to 4 belonging to the Swan $(d3\Pi ga3\Pi u$ system of $C2$. The rotational analysis of these bands is currently in progress.