Knowledge Bank

High resolution infrared spectra of $Cl35CN$ and $Cl37CN$ have been obtained in the region 2000 to $3000cm-1$. The bands $\nu 3,\nu 3+\nu 21,\nu 3+2\nu 20$ and $\nu 2+\nu 1$ have been analyzed for both isotopic species and their vibrational-rotational constants will be reported. In addition, the pure rotational spectra of these molecules in the states $2\nu 20,2\nu 22$ and $\nu 1$ have been obtained. The Fermi resonance between $\nu 1$ and $2\nu 20$ and $\nu 3+2\nu 20$ and $\nu 3+\nu 1$ will be discussed.