Coupling between C-D and C=O motions using dual-frequency 2D IR photon echo spectroscopy

Abstract

Coupling between C-D and C{double bond, long}O vibrational modes of formamide has been characterized by dual-frequency 2D IR spectroscopy. The signals are consistent with those computed assuming an optically dense system at the C{double bond, long}O frequency. A negative off-diagonal anharmonicity of ∼0.85 ± 0.20 cm-1 was obtained and the coupled modes have anticorrelated frequency distributions. Other features including relaxation times, diagonal anharmonicities for the individual C{double bond, long}O and C-D modes and the dephasing dynamics of the cross peak have been determined to characterize the coupling between modes.