Vibrational relaxation times for a model hydrogen-bonded complex in a polar solvent

Bruehl, Margaret; Hynes, James T.

doi:10.1016/0301-0104(93)80238-5

Cited by 58 publications

(57 citation statements)

References 32 publications

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“…A similar decomposition is available for looking at how the different kinds of intermolecular forces influence the friction. 5,17,18,26,27 If we regard our potential energy V as being a sum of electrostatic ͑elec.͒ and Lennard-Jones ͑LJ͒ parts then, we can further divide…”

Section: B Analyzing the Frictionmentioning

confidence: 99%

“…[14][15][16] Recently, however, a somewhat deeper view of the privileged role of electrostatics in vibrational relaxation has be-gun to emerge, at least in a few special cases. Bruehl and Hynes 17 and Gnanakaran et al 18 have emphasized that electrostatics may be important not only in the direct sense of providing the principal forces acting on the vibrating bonds, but also in positioning solvents close enough to the solute that they end up spending a considerable amount of time high on the repulsive wall of the solute-solvent potential. This indirect effect can actually lead to situations in which Lennard-Jones forces dominate the energy relaxation, even in protic solvents.…”

Section: Introductionmentioning

confidence: 99%

“…This indirect effect can actually lead to situations in which Lennard-Jones forces dominate the energy relaxation, even in protic solvents. 17,18 To make matters seemingly more complicated, we ourselves have shown, by a combination of molecular dynamics and instantaneous-normal-mode analysis, that vibrational friction in polar aprotic solvents is completely controlled by the nonelectrostatic portion of the force along a vibrating bond. 19 So what, on the balance, should we be saying about the role of Coulombic forces in vibrational energy relaxation?…”

Section: Introductionmentioning

confidence: 99%

“…One important distinction we have already addressed: [17][18][19] Electrostatic interactions can have very different implications for the equilibrium and nonequilibrium parts of our problem. To put it another way, we need to think separately about the initial conditions and their subsequent dynamical evolution.…”

Section: Introductionmentioning

confidence: 99%

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On the role of dielectric friction in vibrational energy relaxation

Ladanyi

Stratt

1999

The Journal of Chemical Physics

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Articles you may be interested inThe molecular origins of nonlinear response in solute energy relaxation: The example of high-energy rotational relaxation Vibrational energy relaxation, nonpolar solvation dynamics and instantaneous normal modes: Role of binary interaction in the ultrafast response of a dense liquidThe phrase ''dielectric friction'' tends to bring to mind the drag force exerted by a polar liquid on some translating ion or rotating dipolar molecule, but the underlying idea is far more general. Any relaxation process taking place in a polar environment, including those involving solvation and vibrational relaxation, has the potential to be strongly affected by the special dynamics associated with Coulombic forces. Indeed, there is considerable evidence that vibrational energy relaxation is noticeably accelerated in hydrogen-bonding solvents. What is less clear is precisely how electrostatic forces achieve the accelerations they do and to what extent this phenomenon relies on specifically protic solvents. We explore this issue in this paper by using classical molecular dynamics to study the vibrational population relaxation of diatomic solutes with varying levels of polarity dissolved in both dipolar and nondipolar aprotic solvents. We find that the conventional analysis based on partitioning the force autocorrelation function can be usefully extended by adapting an instantaneous perspective; distinguishing between the purely equilibrium effects of the instantaneous liquid structure surrounding a solute and the solely nonequilibrium effects of the relaxation dynamics launched from those initial conditions. Once one removes the powerful influence of electrostatic forces on the liquid structure, either by simple normalization or by looking at the ''force-velocity'' autocorrelation function, the subsequent dynamics ͑and therefore the mechanism͒ of the relaxation is revealed to be dominated by short-ranged repulsive forces, even under the most polar circumstances. The main rate-enhancing effect of Coulombic forces seems to be an equilibrium electrostriction: The solvent is simply ordered around the solute in such a way as to amplify the repulsive forces. At least in our examples, the slowly varying character of Colombic forces actually makes them quite ineffective at any kind of direct promotion of vibrational energy relaxation.

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Section: B Analyzing the Frictionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the role of dielectric friction in vibrational energy relaxation

Ladanyi

Stratt

1999

The Journal of Chemical Physics

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“…The calculations have been applied to the molecular vibrations such as methylchloride [69], Si-H stretching on the crystal silicon surface [70], hydrogen bonding model system [71], HDO [72], azide ion [73, 741, and cyanide ion [40], whose transition frequencies are so high, hR >> kT, that the quantum effect cannot be neglected.…”

Section: Fermi's Golden Rule With Classical Force Autocorrelation mentioning

confidence: 99%