Abstract

Multiple pulse two-dimensional IR spectroscopy is a promising approach to obtain ultrafast snapshots of molecular structures in the condensed phase. Here we show that nonlinear IR spectroscopy exposes the dynamics of the local structure of liquids: results for liquid acetone are obtained. The liquid responds like a molecular excitonic system undergoing structure fluctuations. Isotope dilution with acetone-2-¹³C shifts the C=O frequencies by ~40 cm⁻¹, allowed measurement of the coupling of labeled and unlabeled molecules. Results from new heterodyned 2D transient grating experiments reveal the dynamics of intermolecular energy transfer.

© 2002 Optical Society of America