Knowledge Bank

The infrared spectrum of gas phase methyl nitrite ($CH3ONO$) has been recorded at high resolution between 600 and $4000cm-1$. Methyl nitrite contains a mixture of cis and trans rotational isomers which are interconverted by the N=O torsion. As in the $\nu 8$ vibration of the cis form, the $\nu 9$ vibration is not too congested, consistent with the high barrier to rotation of the methyl group in the cis form. The $\nu 9$, with an origin at $627.9cm-1$, has been assigned by previous workers to the ONO bend of the cis conformer and several hot bands are also present in this region. In this study, a spectrum taken at $0.0015cm-1$ resolution on the PNNL IFS 120/HR in a 20 cm cell was used to assign more than 500 A-type transitions of the cis $\nu 9$ between 600 and $650cm-1$ and a set of excited state constants was determined.