Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5415877 | Journal of Molecular Spectroscopy | 2008 | 15 Pages |
Abstract
The Fourier transform infrared spectrum of gaseous thiophene, C4H4S, has been recorded in the 600-1200 cmâ1 spectral region with a resolution of ca. 0.0030 cmâ1. Five fundamental bands ν13 (B1, 712.1 cmâ1), ν7 (A1; 840.0 cmâ1), ν6 (A1; 1036.4 cmâ1), ν5 (A1; 1081.5 cmâ1) and ν19 (B2; 1084.0 cmâ1) have been analysed by the standard Watson model (A-reduction). Ground state rotational and quartic centrifugal distortion constants have been obtained from a simultaneous fit of ground state combination differences from four of these bands and previous microwave transitions. Upper state spectroscopic constants have been obtained for all five bands from single band fits using the Watson model. A strong c-Coriolis resonance perturbs the close lying ν5 and ν19 bands. We have analysed this dyad system by a model including first and second order Coriolis resonance using the theoretically predicted Coriolis coupling constant Ï19,5c. From this analysis we locate the previously unobserved ν19 band at 1083.969 cmâ1. The rotational constants, ground state quartic centrifugal distortion constants, anharmonic frequencies, and vibration-rotational constants (α-constants) predicted by quantum chemical calculations using a cc-pVTZ basis with B3LYP methodology, are compared with the present experimental data, where there is generally good agreement. A complete set of anharmonic frequencies and α-constants for all fundamental levels of the molecule is given.
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Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
F. Hegelund, R. Wugt Larsen, M.H. Palmer,