Direct Probe of Vibrational Fingerprint and Combination Band Coupling
Ryan P. McDonnell, Kelson Oram, Mark A. Boyer, Daniel D. Kohler, Kent A. Meyer, Edwin L. Sibert, John C. Wright
Abstract
Vibrational fingerprints and combination bands are a direct measure of couplings that control molecular properties. However, most combination bands possess small transition dipoles. Here we use multiple, ultrafast coherent infrared pulses to resolve vibrational coupling between CH 3 CN fingerprint modes at 918 and 1039 cm –1 and combination bands in the 2750–6100 cm –1 region via doubly vibrationally enhanced (DOVE) coherent multidimensional spectroscopy (CMDS). This approach provides a direct probe of vibrational coupling between fingerprint modes and near-infrared combination bands of large and small transition dipoles in a molecular system over a large frequency range.