Abstract

The absorption and fluorescence spectra of anthracene and (9,9`- bianthracene, BA) or (9, 9'- dianthryl) were measured in several polar and nonpolar solvents. It was found that the absorption spectra of BA are decomposed into several bands that are similar to the absorption bands of anthracene, while it observed the loss of decomposition in the fluorescence spectra of BA and seems a broad widely as well as shifting towards the longer wavelength region (redshift) with a significant decrease in intensity especially in polar solvents which indicates the appearance of intra-molecular Exciplex characteristics of BA and occurrence of charge transfer- CT at the Franck Condon locally excited state BA molecule becomes a pair of anthracene ions، cation، and anion, then the resulting fluorescence is from the CT-state, and as a consequence, it observed the decrease in the value of the quantum efficiency and increasing in neutral fluorescence lifetime in polar solvents, such as in ethanol equals (〖 q〗_FM=0.13,τ_M= 182.75 nsec). Furthermore, it was observed that the dissolved oxygen molecules in solutions are constituting an influential quencher factor for the fluorescence intensity in all solvents and especially at polar solvents due to the increasing fluorescence lifetime at CT- state where the intensity and〖 q〗_FM are decreased significantly in this state.