Kinetic Factors Affecting Quantum Yields

The excited state can undergo intersystem crossing to produce the photoactive state A which decays to products P or back to the ground state. It is normal to assume a steady state for the excited states, A and I, and 

From its definition, and substitution from Eq. (7.5), the quantum yield is 

This development shows that several factors in addition to kp can affect the quantum yield. It is not uncommon in this area to study the effect of changing ligand substituents and solvents on O and to use the results to infer the mechanism of the kp step. But such changes in conditions may affect kj, k and/or and thereby make any mechanistic conclusions very tenuous. Similar ambiguities can arise when the solvent is changed. 

Cobalt(III) forms a wide range of substitution-inert (low-spin d ) complexes whose thermal aquation and anation reactions have been thoroughly studied. These provide useful comparisons for photochemical 

Wilson and Solomon suggest that the 7, may decay to the 7j state. 

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