Energy-Gap Law and Room-Temperature Phosphorescence of Polycyclic Aromatic Hydrocarbons Adsorbed on Cyclodextrin/Sodium Chloride Solid Matrices

The energy-gap law was shown to be applicable to the room-temperature solid-matrix phosphorescence of polycyclic aromatic compounds adsorbed on cyclodextrin/salt matrices. No heavy atom was used to enhance the phosphorescence signals. As the energy gap between the lowest excited triplet state and ground state increased, the phosphorescence lifetime of the phosphor increased. The changes in the phosphorescence lifetimes were correlated with the magnitude of the nonradiative rate constants which, in turn, were related to the energy gap between the excited triplet state and ground state. With the correlations developed, it is possible to predict which polycyclic aromatic hydrocarbons will give strong solid-matrix phosphorescence.