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Vibrational dephasing and the Raman non‐coincidence effect of CHBr 3 in isotopic dilution
Author(s) -
Deckert V.,
Asthana B. P.,
Kiefer W.,
Purucker H.G.,
Laubereau A.
Publication year - 2000
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 - 10.1002/1097-4555(200008/09)31:8/9<805::aid-jrs575>3.0.co;2-x
Subject(s) - raman spectroscopy , dephasing , dilution , chemistry , isotope dilution , intermolecular force , laser linewidth , isotopic shift , analytical chemistry (journal) , anisotropy , isotropy , coincidence , raman scattering , spectral line , molecule , optics , thermodynamics , condensed matter physics , laser , physics , mass spectrometry , medicine , alternative medicine , organic chemistry , chromatography , pathology , astronomy
The ν 1 (C–H) stretching mode of CHBr 3 was investigated in the solvent CDBr 3 at room temperature using three‐colour femtosecond CARS and scanning multi‐channel Raman difference spectroscopy (SMT‐RDS). Small but measurable blue shifts (≤1 cm −1 ) of the isotropic part of the Raman scattering relative to the anisotropic component and upon isotopic dilution are the clear signatures of the Raman non‐coincidence effect and isotopic lineshift, respectively. The experimental results are discussed in terms of theoretical models providing insight in the intermolecular coupling mechanisms. The measured shift Δν ID = 0.73 ± 0.02 cm −1 upon isotopic dilution is found to be dominated by the attractive interaction and is to be compared with the non‐coincidence effect of Δν NCE = 1.02 ± 0.05 cm −1 for the neat liquid. A 5% decrease in the dephasing rate 1/ T 2 and a similar change in the linewidth upon infinite dilution are observed and semi‐quantitatively explained via repulsive intermolecular interaction in accordance with an estimate of the corresponding (small) wavenumber shift. Copyright © 2000 John Wiley & Sons, Ltd.