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Title: Rotational study of the CH{sub 4}–CO complex: Millimeter-wave measurements and ab initio calculations

The rotational spectrum of the van der Waals complex CH{sub 4}–CO has been measured with the intracavity OROTRON jet spectrometer in the frequency range of 110–145 GHz. Newly observed and assigned transitions belong to the K = 2–1 subband correlating with the rotationless j{sub CH4} = 0 ground state and the K = 2–1 and K = 0–1 subbands correlating with the j{sub CH4} = 2 excited state of free methane. The (approximate) quantum number K is the projection of the total angular momentum J on the intermolecular axis. The new data were analyzed together with the known millimeter-wave and microwave transitions in order to determine the molecular parameters of the CH{sub 4}–CO complex. Accompanying ab initio calculations of the intermolecular potential energy surface (PES) of CH{sub 4}–CO have been carried out at the explicitly correlated coupled cluster level of theory with single, double, and perturbative triple excitations [CCSD(T)-F12a] and an augmented correlation-consistent triple zeta (aVTZ) basis set. The global minimum of the five-dimensional PES corresponds to an approximately T-shaped structure with the CH{sub 4} face closest to the CO subunit and binding energy D{sub e} = 177.82 cm{sup −1}. The bound rovibrational levels of the CH{sub 4}–CO complex weremore » calculated for total angular momentum J = 0–6 on this intermolecular potential surface and compared with the experimental results. The calculated dissociation energies D{sub 0} are 91.32, 94.46, and 104.21 cm{sup −1} for A (j{sub CH4} = 0), F (j{sub CH4} = 1), and E (j{sub CH4} = 2) nuclear spin modifications of CH{sub 4}–CO, respectively.« less
Authors:
 [1] ;  [2] ; ;  [3] ;  [1] ;  [4] ; ;  [5] ;  [6] ;  [7]
  1. I. Physikalisches Institut, University of Cologne, Zülpicher St. 77, 50937 Cologne (Germany)
  2. (Russian Federation)
  3. Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya St. 5, 142190 Troitsk, Moscow (Russian Federation)
  4. Department of Optics and Spectroscopy, Tomsk State University, 36 Lenin Ave., 634050 Tomsk (Russian Federation)
  5. University Grenoble Alpes, IPAG, F-38000 Grenoble (France)
  6. (France)
  7. Theoretical Chemistry, Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands)
Publication Date:
OSTI Identifier:
22493128
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 15; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 97 MATHEMATICAL METHODS AND COMPUTING; BINDING ENERGY; CARBON MONOXIDE; COMPARATIVE EVALUATIONS; COMPLEXES; DISSOCIATION ENERGY; EXCITATION; EXCITED STATES; GROUND STATES; METHANE; POTENTIAL ENERGY; SPECTRA; SPIN; VAN DER WAALS FORCES