We study coupling mechanism of inter-and intramolecular modes of liquids by using a multi-mode Brownian oscillators model. The coupling between modes comes into play through polarizability and/or potential expanded with respect to vibrational coordinates. We take into account these two causes of coupling and present analytical expressions for the Fourier transform of the time-domain fifth-order Raman signal. We demonstrate a notable sensitivity of the Fourier-transformed quantity to the coupling mechanism through numerical calculations for chloroform. (C) 1997 Elsevier Science B.V.