The Ground and First Excited Torsional States of Acetic Acid

Author： Ilyushin V.V. Alekseev E.A. Dyubko S.F. Podnos S.V. Kleiner I. Margulès L. Wlodarczak G. Demaison J. Cosléou J. Maté B. Karyakin E.N. Golubiatnikov G.Y. Fraser G.T. Suenram R.D. Hougen J.T.

Publisher： Academic Press

ISSN： 0022-2852

Source： Journal of Molecular Spectroscopy, Vol.205, Iss.2, 2001-02, pp. : 286-303

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Abstract

A global fit of microwave and millimeter-wave rotational transitions in the ground and first excited torsional states (v_t = 0 and 1) of acetic acid (CH₃COOH) is reported, which combines older measurements from the literature with new measurements from Kharkov, Lille, and NIST. The fit uses a model developed initially for acetaldehyde and methanol-type internal rotor molecules. It requires 34 parameters to achieve a unitless weighted standard deviation of 0.84 for a total of 2518 data and includes A- and E-species transitions with J ≤ 30 and K_a ≤ 15. While these results represent a significant improvement over past fitting attempts, it should be cautioned that the present data set is dominated by v_t = 0 transitions, and no direct infrared measure of the v_t = 1 ← 0 torsional interval is available.