Simple uniform photoreactions

In Section 2.1.3.3 the details for two simple uniform photoreactions are derived [10]. These are summarised in Table 3.1. 

Mechanisms and photochemical quantum yields of the simple photoisomerisation in dependence on the photophysical pathway 

---

EXPLICIT DIFFERENTIAL EQUATIONS IN PHOTOKINETICS 3.2.1 Rates of simple uniform photoreactions... 

The quantum yield does not depend on the amount of light absorbed The simple uniform photoreaction can be described according to eq. (2.12) by... 

A thermal reaction with just a single elementary step is call simple uniform in the case of a photochemical reaction elementary reactions for which the intermediates can be omitted because of the Bodenstein hypothesis are taken also as a simple one. Examples are both the photoreactions given in Section 2.1.3.3. 

Some other simple uniform mechanisms are the basis of photochemical reactions. These are photoadditions, the photoreduction and some sensitised photoreactions which are discussed in the following. 

In Section 3.2.1 the differential equations for simple uniform photochemical reactions are derived and given by eqs. (3.35) and (3.38). Their integrals can be solved assuming the reactant A starts the photoreaction. 

These assumptions are valid for 2,2, 4,4 -tetra-isopropyIazobenzene which shows a uniform photoreaction. The thermal backward reaction is negligible at room temperature. Thus a graph of ln(10 > — 1) versus the reaction time initially exhibits a straight line. This derivative can be evaluated as a simple actinometric system for radiation in the range between 350 and 390 nm [149], In Fig. 5.26 the reaction spectrum demonstrates the validity of the assumptions above. 

Details for simple non-uniform photoreactions 6.6.2.1 Physically sensitised parallel photoreaction... 

---