Model, cage effects

The traditional difhision model pemiits estimation of the magnitude of the cage effect in solntion according to [37]... 

The simple difhision model of the cage effect again can be improved by taking effects of the local solvent structure, i.e. hydrodynamic repulsion, into account in the same way as discussed above for bimolecular reactions. The consequence is that the potential of mean force tends to favour escape at larger distances > 1,5R) more than it enliances caging at small distances, leading to larger overall photodissociation quantum yields [H6, 117]. 

Figure A3.6.13. Density dependence of die photolytic cage effect of iodine in compressed liquid n-pentane (circles), n-hexane (triangles), and n-heptane (squares) [38], The solid curves represent calculations using the diffusion model [37], the dotted and dashed curves are from static caging models using Camahan-Starling packing fractions and calculated radial distribution fiinctions, respectively [38],...

Otto B, Schroeder J and Tree J 1984 Photolytic cage effect and atom recombination of iodine in compressed gases and liquids experiments and simple models J. Chem. Phys. 81 202... 

Figure 3. Calculated efficiencies. (1) From the cage effect model and no primary radical termination (Case I) (2) From the assumption of an overall efficiency and no primary radical termination (Case II) (3) From the assumption of an overall efficiency and primary radical termination (Case III) ( l) Calculated from equation (A) with fo - 0.663.

The cage effect was also analyzed for the model of diffusion of two particles (radical pair) in viscous continuum using the diffusion equation [106], Due to initiator decomposition, two radicals R formed are separated by the distance r( at / = 0. The acceptor of free radicals Q is introduced into the solvent it reacts with radicals with the rate constant k i. Two radicals recombine with the rate constant kc when they come into contact at a distance 2rR, where rR is the radius of the radical R Solvent is treated as continuum with viscosity 17. The distribution of radical pairs (n) as a function of the distance x between them obeys the equation of diffusion ... 

Molecular-Dynamics Simulation of a Glassy Polymer Melt Rouse Model and Cage Effect. 

How can we use the previous result to derive thermochemical data The most correct procedure would probably the one described by Koenig, Hay, and Finke [324], briefly covered in section 3.2, which accounts for cage effects. However, this model involves parameters that are not available for the example under analysis. Therefore, we follow a cruder (but more typical) approach. 

The importance of the size of the enclosure (reaction cavity) on a reaction course has been a subject of investigation in several laboratories. On the basis of the proposed mechanistic scheme for DBK fragmentation and on the basis of the effective reaction cavity model presented in Section III, the following predictions can be made (a) a relationship will exist between the cage effect and the reaction cavity size (b) the cage effects observed for singlet and triplet benzyl radical pairs will be different (assuming very similar diffusion rates)... 

The rebinding dynamics to microperoxidase are nonexponential due to a solvent cage effect. To deduce the time constant for rebinding CO from the solvent cage, the recombination kinetics were modeled according to... 

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