Infrared Spectrum and Intermolecular Potential Energy Surface of the CO-O₂ Dimer
Abstract
Only a few weakly-bound complexes containing the O2 molecule have been characterized by high resolution spectroscopy, no doubt due to the complications added by the oxygen molecule's unpaired electron spin. Here we report an extensive infrared spectrum of CO-O2, observed in the CO fundamental band region using a tunable quantum cascade laser to probe a pulsed supersonic jet expansion. The rotational energy level pattern derived from the spectrum consists of stacks of levels characterized by the total angular momentum, J, and its projection on the intermolecular axis, K. Five such stacks are observed in the ground vibrational state, and ten in the excited state (v(CO) = 1). They are divided into two groups, with no observed transitions between groups. The groups correspond to different projections of the O2 electron spin, and correlate with the two lowest fine structure states of O2, (N, J) = (1, 0) and (1, 2). The rotational constant of the lowest K = 0 stack implies an effective intermolecular separation of 3.82 Å, but this should be interpreted with caution since it ignores possible effects of electron spin. A new high-level 4-dimensional potential energy surface is developed for CO-O2, and rotational energy levels are calculated for this surface, ignoring electron spin. By comparing calculated and observed levels, it is possible to assign detailed quantum labels to the observed level stacks.
Recommended Citation
A. J. Barclay et al., "Infrared Spectrum and Intermolecular Potential Energy Surface of the CO-O₂ Dimer," Physical Chemistry Chemical Physics, vol. 20, no. 21, pp. 14431 - 14440, Royal Society of Chemistry, May 2018.
The definitive version is available at https://doi.org/10.1039/c8cp02282h
Department(s)
Chemistry
Research Center/Lab(s)
Center for High Performance Computing Research
International Standard Serial Number (ISSN)
1463-9076; 1463-9084
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2018 Royal Society of Chemistry, All rights reserved.
Publication Date
01 May 2018
Comments
The financial support of the Canadian Space Agency and the Natural Sciences and Engineering Research Council of Canada is gratefully acknowledged. RD is supported by the US National Science Foundation (No. CHE-1566246).