Abstract
Solutions of 2,5-diphenyloxazole (PPO) in benzene, toluene, cyclohexane, and hexane are selectively excited by radiation in the wavelength region 3000–1100 Å, and the resulting fluorescence is recorded. It is found that all four solvents transfer excitation energy to the solute in the region in which they strongly absorb. Possible implications of these results for γ and β excitation are considered.