The photochemistry of small molecules has been studied in great detail for many years [1]. Yet the effect of UV light on very large molecules which contain the same basic chromophores was treated rather empirically for a long time until the subject became one of fundamental importance. Naturally, the study of photosynthesis and related processes, the irradiation of proteins and nucleic acids, and the development of synthetic polymers, which are often exposed to the sun's radiation in common usage, have created much practical and theoretical concern in this area. The wealth of information that had been accumulated for small molecules provided a convenient starting point for the consideration of the photochemical properties of “large” molecules. However, a unique situation obtains when chromophores are held on a polymer chain so that straightforward extrapolation could not be justified before extensive studies were carried out on the general photochemistry of typical macromolecular systems.