How Do Hydrogen Bonds Break in Small Alcohol Oligomers?

Title How Do Hydrogen Bonds Break in Small Alcohol Oligomers?
Publication Type Journal Article
Year of Publication 2009
Authors Jiang RM, Sibert EL
Journal Journal of Physical Chemistry A
Volume 113
Pagination 7275-7285
Date Published Jul
Accession Number ISI:000267384500013
Keywords Chemistry, Physical, configurational uniformity, der-waals molecules, diabatic, hydroxyl stretch, infrared-spectroscopy, ir spectroscopy, liquid methanol, methanol oligomers, Physics, Atomic, Molecular & Chemical, states, structural dynamics, Vibrational-energy relaxation
Abstract Recent infrared pump-probe studies on alcohol oligomers in CCl4 solution reveal that, following OH stretch excitation, ultrafast hydrogen bond (H-bond) breaking takes place on a time scale of 1 ps. To shed light on the mechanism of the H-bond breaking, we consider vibrational predissociation of the H-bonded methanol dimer. We construct a four-dimensional model for the dimer including the H-bond stretch, the donor OH stretch, the donor COH bend, and the OH rotation about the CO axis of the donor. Predissociation rates are calculated with Fermi’s golden rule and close coupling approaches. Our results indicate that the predissociation leads to products with highly excited OH rotations. The predissociation rates strongly depend on the hydrogen bond strength. From our results, a simple nonadiabatic curve crossing picture for the predissociation process emerges, which provides a framework for future studies of solvent-assisted vibrational predissociation.
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