Ab Initio Calculations of Torsionally Mediated Hyperfine Splittings in E States of Acetaldehyde

Published

June 15, 2017

Author(s)

Li-Hong Xu, E. M. Reid, B. Guislain, Jon T. Hougen, Eugene A. Alekseev, I. Krapivin

Abstract

Quantum chemistry packages can be used to predict with reasonable accuracy spin-rotation hyperfine interaction constants for methanol, which contains one methyl-top internal rotor. In this work we used these same packages to calculate components of the spin-rotation interaction tensor for acetaldehyde. We then use torsion-rotation wavefunctions obtained from a fit to the acetaldehyde torsion-rotation spectrum to calculate the expected magnitude of hyperfine splittings analogous to those observed at relatively high J values in the E symmetry states of methanol. We find that theory does indeed predict doublet splittings at moderate J values in the acetaldehyde torsion-rotation spectrum that closely resemble those seen in methanol, but that the factor of two decrease in hyperfine spin-rotation constants compared to methanol, puts even the largest of the acetaldehyde splittings a factor of two below presently available Lamb-dip resolution.

Citation

Journal of Molecular Spectroscopy

Volume

342

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.jms.2017.06.008

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Keywords

Ab initio calculations, Acetaldehyde, Hyperfine splittings, Lamb-dip spectroscopy, Torsion-rotation E states

Citation

Xu, L. , Reid, E. , Guislain, B. , Hougen, J. , Alekseev, E. and Krapivin, I. (2017), Ab Initio Calculations of Torsionally Mediated Hyperfine Splittings in E States of Acetaldehyde, Journal of Molecular Spectroscopy, [online], https://doi.org/10.1016/j.jms.2017.06.008, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=923320 (Accessed October 16, 2025)