Polarization selectivity of nonresonant spectroscopies in isotropic media

We present an analysis of the contributions of of the first- and second-derivative tensors of the many-body polarizability to third-and fifth-order nonresonant spectroscopies in isotropic media. Collision-induced effects are shown to have a notable influence on the second-derivative polarizability tensor (Pi((2))) for intermolecular modes. As a result, polarization selectivity in nonresonant. intermolecular spectroscopies can be achieved in fifth-order spectroscopies. Additionally, terms in fifth-order spectroscopy that arise from three interactions through Pi((2)) may not be negligible in many liquids. Our analysis shows that there exists no straightforward relationship between the observables in third-and fifth-order intermolecular spectroscopies. The predictions of this analysis are tested against the available experimental data for CS2. (C) 1997 American Institute of Physics. [S0021-9606(97)51947-7].