Knowledge Bank

We have recently completed the analysis of new absorption measurements involving the $1110,12\circ ,1220,1310,1330,2000,0400$, and $0510$ levels of HCN. These measurements were combined with laser measurements on HCN, new microwave measurements, and past infrared and microwave measurements in a new evaluation of the vibrational and ro-vibrational constants for HCN. Intensity effects were observed which resulted from the l-type resonance of the $1200$ and $1220$ levels. Transitions of the type $\Delta -\Sigma$ were observed in HCN for the first time. New assignments will be suggested for those HCN laser lines which have hitherto been unassigned.