Chapter 25 – Actinometry

Actinometry refers to the process of determining the intensity of light sources. Recently, the insertion of photochromic systems in polymer blocks or matrices has aroused great interest, because devices for information storage or for the measurement of light require such systems. The transformation of the rate laws from solution to viscous or solid medium was undertaken requires the introduction of the transformed time scale and the inclusion of diffusion processes in the rate laws. The rates of photochemical reactions are influenced by the intensity of the source of irradiation, which has to be known. Otherwise there is no possibility to quantify photochemical reactions. Detailed kinetic examinations (true partial photochemical quantum yields and thermal rate constants) are a prerequisite for classification of photochromic chemicals like dihydro-indolizines or azobenzene being valid in systems for either information storage or chemical actinometry.