Model for spectral artifacts in two-dimensional four-wave mixing spectra from absorption and refractive index dispersion at infrared resonances

Doubly vibrationally enhanced four-wave mixing (DOVE-FWM) is a new techniqu e that is capable of providing two-dimensional spectra. These methods often require scanning lasers over infrared absorption features where the index of refraction dispersion and the sample absorption distort the 2D spectra. In order to test a quantitative model for treating these artifacts, we have chosen a simple model system with an isolated absorption feature and we ha ve compared the line shapes of a resonant Raman feature for a series of dif ferent concentrations and experimental scanning strategies. We have identif ied the 2D spectral signatures that accompany the dispersion and absorption effects and we have shown that they are qualitatively similar to the effec ts introduced by singly vibrationally enhanced (SIVE) four-wave mixing. We find that the spectral changes are substantial and must be treated correctl y if one is to obtain an accurate treatment of multiresonant data.