Knowledge Bank

The $\nu 4$ fundamental band of both the trans and the cis isomers of $HNO2$ ranges in an infrared atmospheric window. The previous spectroscopic investigations reported in the literature (1-3), although accurate, present however limitations either in the range scanned or in the spectral resolution and intensity. We have refined the analysis on the basis of improved experimental conditions, both of instrumental and chemical natures. Some 1950 lines of a type are now assigned to the $\nu 4$ fundamental band of trans-$HNO2$ and over 3100 lines of a and b-type to the $\nu 4$ fundamental band of $cis-HNO2$. The results will be presented and relative intensity information will be discused.