摘要: DELAYED fluorescence lifetimes and spectra have been observed from crystals of naphthalene, anthracene, pyrene, 3,4-benzpyrene, t-stilbene p-terphenyl, using conventional techniques1. In each case a delayed spectrum was with resolution 8 nm, the being identical prompt spectrum. Precautions reported necessary for observation microcrystalline samples2 were not found important in present work, as used at least 1 mm thick.