Approximate Selection Rules for | K | = 1-0 and 1-1 Tunneling-Rotation Transitions in the Methanol Dimer

Published

September 1, 2000

Author(s)

N Ohashi, Jon T. Hougen

Abstract

Approximate K = 0 and |K| = 1 tunneling-rotation eigenfunctions for the four A, four E, and one G symmetry species present in the methanol dimer, derived from molecular parameters obtained previously from a least squares fit to transition frequencies involving K = 0 and 1 levels, are used to clarify some apparent contradictions associated with traditional b-type and c-type transition designations in the E and G tunneling-rotational states of this dimer. These approximate eigenfunctions also predict strong and weak line intensities which are consistent with the pattern of strong a-type, b-type, and c-type transitions observed, thus supporting our previous separate-K-state analysis based only on energy level positions. Some of the predicted weaker a-type transitions should be experimentally observable with somewhat more signal averaging.

Citation

Journal of Molecular Spectroscopy

Volume

203

Issue

No. 1

Pub Type

Journals

Keywords

a-type, b-type and c-type transitions, G₃₆ molecular symmetry group, intensities, methanol dimer, transition moment direction, tunneling-rotation eigenfunctions

Citation

Ohashi, N. and Hougen, J. (2000), Approximate Selection Rules for | K | = 1-0 and 1-1 Tunneling-Rotation Transitions in the Methanol Dimer, Journal of Molecular Spectroscopy (Accessed October 24, 2025)