Polarisation and material dependence of degenerate four-wave mixing transients in molecular fluids

The contributions of various microscopic mechanisms to the nonlinear optical response of molecular fluids are analysed for the case of degenerate four-wave mixing on the nanosecond timescale. A quantitative description of the transient responses obtained with different polarisation combinations is obtained. It is shown that this description applies well to experimental data gathered on a range of fluids and that molecular parameters that specify the amplitude and time dependence of the transients may be reliably measured.