Evaluation of photoreactions superimposed by thermal reactions

The evaluation of kinetic data is more complicated if an additional thermal reaction is superimposed on the photoreaction. In addition to the ED-diagrams given in Section S.3.3.1 some further examples of kinetic analysis can be given. Typical examples are the reactions of photochromic substances either belonging to the classes of dihydroindolizine derivatives, fulgides, or even azobenzene-derivatives. This thermal step either can be a backward 

This equation [153] includes the thermal step compared to the pure photochemical approach given by 

Rearrangement and formal integration supplies the following equations [153,154]  

F is the averaged photokinetic factor within the time interval of measurement. In eq. (5.130) the thermal rate constant is determined independently. 

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