Photochromism photoelectric effects

For normal chemical systems, the characterization of mixtures of compounds is undesirable and generally unnecessary if means of separation of the components are available. However, photochromic systems inherently display properties of mixtures except when the system is completely converted to either of its forms. This causes measurements of heats of combustion, photoelectric effects, and electrical conductivity to be particularly difficult. A variety of such studies is presented in the following sections to illustrate the utility of these measurements. 

Since photoelectric effects vary widely for different compounds one would predict some change should accompany photochromic activity which indeed generates new electronic systems. These effects should be unique for each photochrome and hence there should be no general relationship between photochromism and photoelectric activity. This was found to be the case by Rao and Watson (168). 

Strontium cyanoplatinate when exposed to x-rays exhibits photochromism and a greatly enhanced photoelectric effect (148). However, the exact relationship of this effect to the energy states involved has not been elucidated. This statement also applies to a number of organic photochromes which have been investigated, such as certain hydrazones (169), and aldehyde-amines (164). 

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