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The Rotational Spectrum of the Ground State of Methylamine
Published
Author(s)
Vadim V. Ilyushin, E A. Alekseev, S F. Dyubkoa, R A. Motiyenkoa, Jon T. Hougen
Abstract
Recent progress is reported in measuring, assigning and fitting the rotational spectrum of the ground vibrational state of methylamine, CH3NH2, a spectrum complicated both by internal rotation of the methyl top and by inversion of the amino group. New measurements of 513 rotational transitions with J up to 30 and K up to 9 were carried out between 49 and 326 GHz using the millimeter-wave spectrometer in Kharkov. After removing the observed quadrupole hyperfine splittings, these new data along with previously published measurements were fitted to a group-theoretical high-barrier tunneling Hamiltonian from the literature, using 57 parameters to give an overall weighted standard deviation of 0.79 for 850 far-infrared and 668 microwave transitions in the ground state. The root-mean-square deviation of 0.016 MHz obtained for 366 millimeter-wave transitions measured with 0.020 MHz accuracy represents an approximately 30-fold improvement in fitting accuracy over past attempts.
Citation
Journal of Molecular Spectroscopy
Volume
229
Issue
No 2
Pub Type
Journals
Keywords
amino group inversion motion, high-barrier tunneling formalism, least-squares fit, methyl group internal rotation, methylamine, microwave spectrum
Citation
Ilyushin, V.
, Alekseev, E.
, Dyubkoa, S.
, Motiyenkoa, R.
and Hougen, J.
(2005),
The Rotational Spectrum of the Ground State of Methylamine, Journal of Molecular Spectroscopy
(Accessed June 6, 2023)