AbstractThe molecular orientation behavior and molecular motions in polymer solids were investigated utilizing the photoluminescence phenomena. The basic principles of the fluorescence methods were given and the unique features of those methods were discussed with examples of application in the study of the structure of polymer solids. From the angular distribution of the polarized components of fluorescence emitted from the specimen the molecular orientation patterns were ascertained. Examples were given for molecular orientation patterns observed during the deformation of films of polyvinylalcohol and polypropylene. The molecular motions of the relaxation time in the range of 10−12sec to 10−6sec were studied using the lifetime of excitation of fluorescent molecules as the reference time scale. The molecular motions in polyethylene melts were investigated by the rotational depolarization of fluorescence. The multiple transitions in polystyrene and polyvinylalcohol were studied by introducing fluorescent molecules capable of internal rotation. The application of excimer emission phenomenon in the study of molecular structure was also discus