Participation of the anthracene/trans, trans-2,4-hexadiene exciplex in anthracene photodimerization

Observations with the anthracene(A)/trans,trans-2,3-hexadiene(D) system revealing diene enhancement of the photodimerization in the parent hydrocarbon were previously reported. There was disagreement on the dimerization mechanism. Detailed observations are reported which firmly establishes a mechanism involving reaction of ground state anthracene with an exciplex /sup 1/(AD) as the mechanism for enhanced photodimerization in this system. (JSR)