The yl (C-H) stretching mode of CHBr3 was investigated in the solvent CDBr3
at room temperature using three-colour femtosecond CARS and scanning multi
-channel Raman difference spectroscopy (SMT-RDS), Small but measurable blue
shifts (less than or equal to 1 cm(-1)) of the isotropic part of the Raman
scattering relative to the anisotropic component and upon isotopic dilutio
n are the clear signatures of the Raman non-coincidence effect and isotopic
lineshift, respectively. The experimental results are discussed in terms o
f theoretical models providing insight in the intermolecular coupling mecha
nisms. The measured shift Delta nu(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 Delta nu(NCE) = 1.02 +/- 0.0
5 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 a
ccordance with an estimate of the corresponding (small) wavenumber shift. C
opyright (C) 2000 John Wiley & Sons, Ltd.