Excimers

Excimers are dimers with associated excited electronic states, dissociative ground states, and structureless emission spectra. Noble and other monatomic gases form atomic excimers. Aromatic molecules form excimers in fluid solutions, liquids, crystals and polymers, at crystal defects, and intramolecularly. Excimer interaction is attributed to configurational mixing of exciton and charge resonance states. The helium excimer and pyrene crystal dimer potential curves are compared. Aromatic excimers are discussed. Related photophysical studies on atomic excimers are considered. Saturated amines, which exhibit vapour and solution excimer fluorescence, provide a link between atomic and aromatic excimers. Aromatic molecules form complexes, exciplexes or mixed excimers with different molecules, and noble gas atoms form complexes or exciplexes with different atoms. Review completed in 1975.