Vibrational dynamics hydrogen-bonded systems

Ultrafast vibrational spectroscopy offers a variety of techniques for unraveling the microsopic dynamics of hydrogen bonds occurring in the femto- to picosecond time domain. In particular, different vibrational couplings can be separated in nonlinear experiments by measuring vibrational dynamics in real-time. Both coherent vibrational polarizations and processes of population and energy relaxation have been studied for a number of hydrogen bonded systems in liquids [1],... 

Both approaches have been demonstrated for a variety of flexible hydrogen bonded systems. In this article we have utilized the techniques to discuss the role of (classical and quantum) dynamics on vibrational properties and electronic excitation and band gap properties. In addition we have also shown how these techniques can be used to obtain new and rather intriguing physical results such as the amphiphilic nature of the hydrated proton and have also shown how AIMD simulations can be utilized as a tool to understand differences between different experimental spectroscopic measurements. 

Neutron inelastic scattering techniques have been widely applied to the study of vibrational and rotational dynamics in hydrogenous molecular systems.1 The bulk of this research has been concerned with the study of intermolecular and interionic motions in solids, but a limited yet significant amount of effort has been directed toward the study of large-amplitude intramolecular vibrations, most notably torsional vibrations and hydrogen-bond modes.2 The present paper is restricted primarily to a discussion of the application of neutron scattering to the study of torsional vibrations and barriers to rotation of methyl groups in molecules. We will present several examples in which neutron spectra have provided information complementary to that obtained by the more widely available and applicable infrared and Raman techniques. We will also discuss in simple terms some limitations and pitfalls of the neutron technique and the interpretation of neutron spectral results. 

Vibrational spectroscopy with neutrons sheds new light on proton dynamics in solids. New representations of proton dynamics in hydrogen-bonded systems such as... 

In contrast to the subsystem representation, the adiabatic basis depends on the environmental coordinates. As such, one obtains a physically intuitive description in terms of classical trajectories along Born-Oppenheimer surfaces. A variety of systems have been studied using QCL dynamics in this basis. These include the reaction rate and the kinetic isotope effect of proton transfer in a polar condensed phase solvent and a cluster [29-33], vibrational energy relaxation of a hydrogen bonded complex in a polar liquid [34], photodissociation of F2 [35], dynamical analysis of vibrational frequency shifts in a Xe fluid [36], and the spin-boson model [37,38], which is of particular importance as exact quantum results are available for comparison. 

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