Singlet–singlet intermolecular optical energy transfer from naphthalene to benzophenone in the vapor phase

By using the exothermic energy transfer as a function of pressure, the rate constant for diffusion was evaluated for benzophenone/naphthalene and naphthalene/benzophenone systems. In principle the optical energy absorbed by a complex molecule raises that molecule to one of its excited states, and afterwards this excitation energy decays through the different relaxation channels. Initially, electronically excited naphthalene “S1” state emits photons in the fluorescence band of naphthalene and these emitted photons, as a stream of particles, are absorbed by the acceptor molecule benzophenone, then excited benzophenone fluoresces. In this investigation, sensitized fluorescence decay times in different conditions were measured for naphthalene–benzophenone system in the vapor phase, and found to be 12 ± 1 ns. The ultraviolet-visible spectra of the system in the vapor phase at room temperature conditions were broad and structureless.