First high-resolution analyses of the nu8 and nu8+nu9 spectral regions of 35ClONO2: determination of the nu9 band centre

Abstract

A ro-vibrational analysis of the C-type _8 fundamental band of 35ClONO2 as well as the hot band ƒÞ8+ƒÞ9 - ƒÞ9 has been carried out using a Fourier-transform infrared spectrum of natural chlorine nitrate recorded with a resolution of 0.000 94 cm-1 at a temperature of 190 K. Accurate upper state constants have been determined for both bands including the following band centres: ƒÞ0(ƒÞ8) = 711.207 63(9) and ƒÞ0(ƒÞ8+ƒÞ9 - ƒÞ9) = 714.905 0(12) cm-1. These constants have been used, together with a transition moment operator that takes into account the observed Herman¡VWallis effect, to successfully model the experimental spectrum. In addition, the constants of the 8191state have been used to model the ƒÞ8+ƒÞ9 band, allowing us to assign nearly 100 Q-branch transitions and, therefore, to determine the band centre of the ƒÞ8+ƒÞ9 band, ƒÞ0(ƒÞ8+ƒÞ9) = 838.626 9(15) cm-1. Consequently this allows us to obtain the band centre of ƒÞ9: ƒÞ0(ƒÞ9) = 123.721 9(20) cm-1. This establishes unambiguously that the band at 714.9 cm-1 previously attributed to ƒÞ5- ƒÞ9 is actually the ƒÞ8+ƒÞ9 - ƒÞ9 hot band.