Short range caging effects for reactions in solution. I. Reaction rate constants and short range caging picture

The effects of short range solvent structure and short range dynamical correlations are investigated for the steady state rate constant k for solution reactions influenced by diffusion. The description is in terms of a Smoluchowski equation describing relative motion of two molecules in an outer spatial translational region, supplemented by a sink term that accounts for dynamics in an inner reaction zone. In the outer region, solvent structural effects are included by a potential of mean force, which exhibits a short range well and barrier combination leading to ’’potential caging.’’ Outer region short range dynamical correlations are included via a separation‐dependent diffusion coefficient, leading to ’’dynamical caging’’ as relative motion is showed at small separations. These two short range effects are neglected in standard diffusion treatments. We find that k is only modestly influenced by the above short range effects. In order to expose short range structure and correlation influence in a more sen...

[1]  R. M. Noyes.  A Treatment of Chemical Kinetics with Special Applicability to Diffusion Controlled Reactions , 1954 .

[2]  M. Fixman,et al.  Atom recombination in liquids on a picosecond timescale , 1976 .

[3]  Irwin Oppenheim,et al.  Molecular Theory of Brownian Motion for Several Particles , 1971 .

[4]  J. Freed,et al.  The Theory of Chemically Induced Dynamic Spin Polarization , 1976 .

[5]  Don L. Bunker,et al.  Photolytic cage effect. Monte-Carlo experiments , 1972 .

[6]  H. C. Andersen.  The Structure of Liquids , 1975 .

[7]  S. Chandrasekhar.  Stochastic problems in Physics and Astronomy , 1943 .

[8]  J. Hynes,et al.  Short range caging effects for reactions in solution. II. Escape probability and time dependent reactivity , 1979 .

[9]  J. Hynes,et al.  Coupling of translational and reactive dynamics for a Fokker–Planck model , 1978 .

[10]  D. Lévesque,et al.  The potential of mean force for an infinitely dilute ionic solution , 1978 .

[11]  E. Rabinowitch,et al.  Collision, co-ordination, diffusion and reaction velocity in condensed systems , 1937 .

[12]  R. Cukier,et al.  Kinetic theory derivation of a pair configuration space diffusion equation , 1978 .

[13]  J. Hynes,et al.  Reactive dynamics for diffusive barrier crossing , 1978 .

[14]  Hiromi Yamakawa,et al.  Modern Theory of Polymer Solutions , 1971 .

[15]  S. H. Northrup,et al.  On the description of reactions in solution , 1978 .

[16]  F. C. Goodrich,et al.  Random Walk with Semiadsorbing Barrier , 1954 .

[17]  F. Mandel,et al.  Numerical Solutions of the Percus–Yevick Equation for the Lennard‐Jones (6–12) and Hard‐Sphere Potentials , 1970 .

[18]  P. L. Fehder,et al.  Microscopic mechanism for diffusion and the rates of diffusion-controlled reactions in simple liquid solvents , 1970 .

[19]  David Chandler,et al.  Statistical mechanics of chemical equilibria and intramolecular structures of nonrigid molecules in condensed phases , 1976 .

[20]  R. Lyon.  The Cage Effect in Solution and Gas Phase with Application to the Determination of Rate Constants , 1964 .

[21]  K. Schulten,et al.  The generation, diffusion, spin motion, and recombination of radical pairs in solution in the nanosecond time domain , 1977 .

[22]  J. B. Birks,et al.  Organic Molecular Photophysics , 1975 .

[23]  W. Ware,et al.  Kinetics of diffusion‐controlled reactions: Transient effects in fluorescence quenching , 1975 .

[24]  B. Alder,et al.  Molecular Dynamics. VI. Free‐Path Distributions and Collision Rates for Hard‐Sphere and Square‐Well Molecules , 1968 .

[25]  V. K. La Mer,et al.  The kinetics of activation-diffusion controlled reactions in solution; the temperature dependence of the quenching of fluorescence. , 1948, Journal of the American Chemical Society.

[26]  Peter G. Wolynes,et al.  Slip boundary conditions and the hydrodynamic effect on diffusion controlled reactions , 1976 .

[27]  H. Johnston.  Gas Phase Reaction Rate Theory , 1966 .

[28]  P. L. Fehder,et al.  Microscopic Mechanism for Self‐Diffusion and Relative Diffusion in Simple Liquids , 1971 .