Solvation dynamics in polar liquids

Abstract

Ion and dipole solvation kinetics is studied within the framework of the mean-spherical approximation (MSA). The solvation dynamics in nonassociated polar solvents involves a hierarchy of relaxation times in accordance with Onsager's "inverted snowball" picture. The average solvation time is determined by the relative solvent and solute sizes and by the dynamic screening. The dipole solvation is slower than ion solvation due to the shorter spatial range of interaction. The theoretical results are confronted with experimental data on timeresolved fluorescence shifts of dipolar probe molecules in nonassociated polar solvents. The experimental kinetic data exhibit a crossover from a short-time dipole solvation behavior to ion solvation at intermediate and long times. For associated polar solvents the Onsager picture has to be modified to account for structure breaking in the first solvation shell(s).

Dielectric Aspects of Dipolar Solvation at the Glass Transition

“…As mentioned earlier, the d-MSA model for a Debye liquid results in a dispersive Cd(t) decay. Interestingly, such a decay in a model calculation for a Debye system displays a range of time constants in these limits TL::::; T ::::; To [31]. Since this result refers to a constant charge distribution, the TL limit should be more related to continuum responses, i.e.…”

“…The theory of choice is the dynamic (d-MSA) extension of the MSA [30] formalism as reported by Rips et al [12,31], since it combines a microscopic picture by means of differently responding solvent shells with a straightforward algorithm for predicting C(t) provided that an analytic expression for B(W) is available. As in the line shape theory, the model rests on point dipoles centered in spherical cavities.…”

“…In the dynamic limit, i.e. assuming identical relaxation patterns for all sites, the calculation for the solvation of a dipole reads [31] (11.9a) where .9). Near the glass transition, however, the typically pronounced temperature dependence of relaxation times calls for a precise coincidence of absolute temperatures for the two techniques to be compared.…”

Misleading aspects of the viscosity effect on the heterogeneous electron transfer reactions

“…This problem was extensively discussed in theoretical papers [4][5][6][7][8][9][10] but only rare attempts can be found on its application to real systems [11][12][13]. An evident reason of this disbalance is the complexity of theoretical relations for the reaction rate.…”

Reactivity and Dynamics at Liquid Interfaces

“…Other approximations take into account the finite size of the liquid molecules. [527][528][529][530] Extensive theory and computer simulation work has been able to clarify the molecular mechanisms of solvation dynamics in bulk liquids over the last 3 decades. 390,491 One of the most important conclusions from this body of work is that most of the contribution to polar solvation dynamics comes from the solute's first solvation shell.…”