The Dynamic Behaviour of Radical Pairs

The Dynamic Behaviour of BadiccU Pairs A simple model (Fig. 4) will assist in visualizing the time-dependent variation of the separation and hence the interaction of the components of a radical pair. 

In Fig. 4, nucleus Hi is coupled to the electron on R and nucleus Hj is coupled to the electron on R by the hyperfine terras otj and j, respectively. The inter-radical separation is denoted by X, and Jg is the electron exchange integral. The two radicals move relative to each other and, as shown above, this changes the values of Jge- 

Consider a geminate radical pair, its component radicals in close proximity and therefore having correlated electron spins reflecting the electronic spin state of the precursor, Three different situations can be envisaged. 

Immediately after formation of the geminate pair (time, fj) the component radicals are close together Xj is small and Jee therefore d Fgi, large. Thus Jge j  

At a later time 2, the two radicals will have diffused apart slightly or X2 Xj which implies that Jee( 2) Jeeih)- Since di gx( 2) - st( i) h can be chosen so that the value of Jgg s ] 

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