Luminescence from Aromatic Polymers, Monomers, and Dimers under High-Energy Electron Excitation

The luminescence spectra of various polymers and solid-model compounds induced by 1-MeV electrons are reported and interpreted. The presence of enhanced triplet emission and absence of singlet emission from poly(p-xylene), poly(monochloro-p-xylene), and the model compound dibenzyl are interpreted on the basis of a molecular resonance model. Some triplet excimer and other long-wavelength (450–550-mμ) emission were also observed in these spectra. The spectra of the monomers p-xylene and 2-chloro-p-xylene consisted primarily of long-wavelength emission (400–600 mμ), while the spectra of frozen toluene and durene exhibited both neutral molecule singlet and the long-wavelength emission. Benzene exhibited only singlet, singlet excimer, triplet, and triplet excimer emission. The polymers poly(ethylene-2,6-naphthalene-dicarboxylate), poly(ethyleneterephthalate), and polysulfone emitted primarily from singlet and singlet excimer states. The model compounds for these polymers, dimethyl-2,6-naphthalenedicarboxylate, dimethylterephthalate, and methyl-p-toluenesulfonate exhibited varying amounts of singlet, triplet, excimer, and neutral or ionic radical emission.