Simultaneous Analysis of Rovibrational and Rotational Spectra of thev5= 1 andv8= 1 Vibrational Levels of Propyne

Abstract

The microwave and submillimeter wave spectra of propyne between 17 and 358 GHz were measured and the rotational transitions in thev8= 1 excited vibrational state of the CH3rocking vibration were assigned. About 1050 wavenumbers of the ν8vibration–rotation fundamental band and about 600 wavenumbers of the ν5fundamental band of the[formula]stretching vibration were assigned from the infrared spectrum between 910 and 1130 cm−1which was used previously (G. Graneret al., J. Mol. Spectrosc.161,80–101 (1993)) in the analysis of the combinationv9=v10= 1 and thev10= 3 overtone levels (ν9being the[formula]bending and ν10the[formula]bending vibrations). The rovibrational and rotational data corresponding to the two fundamental levels were analyzed simultaneously in least-squares fits using a model which treats together all the vibrational levels in the region around 1000 cm−1with their strong anharmonic and vibration–rotation resonances. The refined parameters reproduce the infrared and submillimeter wave data of thev5= 1 level with standard deviations of 0.32 × 10−3cm−1and 59 kHz, respectively, while for thev8= 1 level the standard deviations were 0.41 × 10−3cm and 290 kHz. The refined parameters of the combination and overtone levels provide reliable predictions for future submillimeter wave studies.