Chemical reaction and rotational diffusion rates

The time scale over which a chemical reaction occurs is 1/k, where k i is the observed pseudo first-order reaction rate. The time scale over which a molecule re-orients is Trot, which is, according to the simple Debye model of rotational Brownian motion 

This section is concerned with the rates of re-orientation of typical reactants in solution and upon both theoretical analyses and experimental studies of such. Molecules which may display orientationally anisotropic reactivity are indicated and the modifications to the rate of mutual diffusion and chemical reaction are considered. 

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