Concerning the participation of the anthracene/N,N-dimethylaniline exciplex in anthracene photodimerization

Steady-state and transient fluorescence measurements have been made using mixtures of anthracene and N,N-dimethylaniline in benzene. These measurements show that the exciplex lifetime is shortened as the N,N-dimethylaniline concentration is increased, possibly due to the formation of a triplex. The exciplex lifetime is independent of anthracene concentration for (A) less than or equal to 0.03 M, but decreases at high anthracene concentration. A study of anthracene photodimerization suggests that the exciplex or a higher excited aggregate participates in this reaction at high anthracene concentration and that the presence of oxygen enhances dianthracene yields. Rate constants for several of the photophysical and photochemical processes are reported.