ASSIGNMENT OF THE $\nu_{9}$ FUNDAMENTAL OF THE CIS CONFORMER OF METHYL NITRITE IN THE HIGH RESOLUTION FTIR SPECTRUM

Abstract

Author Institution: Department of Chemistry, Idaho State University; Department of Chemistry, Pacific Northwest National LaboratoryThe infrared spectrum of gas phase methyl nitrite ($CH_{3}ONO$) has been recorded at high resolution between 600 and $4000 cm^{-1}$. 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 $627.9 cm^{-1}$, 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 $0.0015 cm^{-1}$ 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 $650 cm^{-1}$ and a set of excited state constants was determined