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Microwave Rotational Spectral Study of CH3CN-H2O and Ar-CH3CN



Francis J. Lovas, J. Sobhanadrib


The microwave spectrum of the molecular complex of acetonitrile (CH3CN) with water (H2O) has been studied with a pulsed-beam Fourier Transform Microwave Spectrometer (FTMW) from a gas sample of 1 % by volume of CH3CN in Ar flowed over a water sample. The frequency coverage was about 9 GHz to 22 GHz for various isotopomers. The CH3CN-H2O complex exhibited a symmetric top spectrum for two tunneling components, whereby the water subunit tunnels between two equivalent forms. The molecular structure was determined with the aid of spectral studies of isotopically substituted monomers containing 13C, 15N and 18O and mono- and di-deuterated water. In the process of measuring the 13CH3CN-H2O species, we observed some nearby transitions for the Ar-13CH3CN complex. Since the molecular structure of the Ar complex in the literature was not completely determined, we also measured several isotopomers of it to improve the molecular structure. The rotational analyses provide the rotational, centrifugal distortion and nuclear quadrupole coupling constants for all of the isotopomers analyzed.
Journal of Molecular Spectroscopy


acetonitrile, dimer, microwave spectrum, rotational spectrum, structure, water


Lovas, F. and Sobhanadrib, J. (2014), Microwave Rotational Spectral Study of CH3CN-H2O and Ar-CH3CN, Journal of Molecular Spectroscopy, [online], (Accessed May 23, 2024)


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Created December 17, 2014, Updated November 10, 2018