Raman spectra corresponding to C=O stretching mode of ethyl acetate (C$_4$H$_8$O$_2$) and $N,N$-dimethyl formamide (C$_3$H$_7$NO) in methanol (CH$_3$OH) and carbon tetrachloride (CCl$_4$) solvents were investigated in the region 1600–1800 cm$^{−1}$. The variations of bandwidths corresponding to isotropic and anisotropic components of the C=O stretching mode with varying solvent concentration were discussed using different mechanisms. The variation in the vibrational and reorientational correlation times with concentration have been explained in terms of self-association, diffusion mechanism, formation of hydrogen bond and screening effect. The Onsager–Fröhlich dielectric model on anisotropy shift has been tested. This model holds good for the solute–CH$_3$OH system. However, the exponential curve for the solute–CCl$_4$ system shows repulsive type of intermolecular forces playing a vital role in such complex system.