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High resolution Raman spectroscopy of gases with laser sources. VI. The rotaitional spectra of 1,3,5‐trifluorobenzene and hexafluorobenzene
Author(s) -
Schlupf Joseph,
Weber Alfons
Publication year - 1973
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250010102
Subject(s) - hexafluorobenzene , chemistry , raman spectroscopy , bond length , spectral line , analytical chemistry (journal) , molecule , optics , physics , organic chemistry , astronomy , chromatography
The pure rotational Raman spectra of 1,3,5‐trifluorobenzene and hexafluorobenzene have been photographed under high resolution using a single mode argon laser as the exciting source. The observed spectra consist of sharp, highly symmetric lines which form well developed R ‐ and S ‐branches. The analysis of the spectra was performed on the basis of the theory of the non‐rigid, symmetric top rotor. The following ground state constants were determined. For 1,3,5‐trifluorobenzene, B o = 0.058651 7 ± (5 × 10 −7 ) cm −1 and Dj = (1.89 ± 0.04) × 10 −9 cm −1 ; for hexafluorobenzene, B o = 0.034316 5 ± 9 × 10 −7 cm −1 and Dj = (0.70 ± 0.04) × 10 −9 cm −1 . The CF bond lengths for these molecules were determined by assuming the values of the carbon ring parameters of benzene. The CF bond lengths ( r 0 ‐values) of 1,3,5‐trifluorobenzene and hexafluorobenzene are then, respectively, 1.304 Å and 1.321 Å. These values are in good agreement with the CF bond lengths determined by means of the electron diffraction technique.