Survey on approaches for selected examples

If the differential equations for the degrees of advancement have to be solved in a numerical manner, the computational expenditure can be increased drastically. If the quantum yields of the partial steps of a reaction depend on the amount of light absorbed in different ways, for example if slow dark reactions have to be considered, in these cases the method will fail. Then, the partial differential equations have to be solved numerically. 

In this and the previous chapter different approaches have been demonstrated to solve the differential equations for a variety of reaction mechanisms. Besides the set-up of differential rate equations for concentrations, the degree of advancement is introduced to reduce complex systems. Furthermore reduced degrees of advancement are demonstrated to result in gen- 

Comparison of different approaches to handle the simple photoisomerisation (A— 

Most integrals cannot be solved in a closed form because of the time dependence of the photokinetic factor (except at specific reaction conditions). Therefore the integrals have to be solved numerically. When the solution cannot be homogenised during the photoreaction by stirring (viscous media) dependencies on time and position have to be taken into account. 

For two typical photoreactions these approaches are compared and summarised in Tables 3.12 and 3.13. 

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