No abstract

Heavy-atom effects on the free radical yield and the triplet yield of the fluorescence quenching were studied in acetonitrile by using 9,10-dicyanoanthracene as the electron-accepting fluorescer and a series of para-halogenated anisóle (I), aniline (II), and A./V-dimethylaniline (III) as the electron-donating quenchers. increases as the atomic number of the halogen substituent increases for all the systems, whereas decreases for the system I and does not change for the systems II and III. These heavy-atom effects are interpreted in terms of the spin-orbit coupling between the singlet exciplex and the locally excited triplet state for the system I, and in terms of the spin-orbit coupling between the geminate radical pair state with singlet spin and the locally excited triplet state for the systems II and III.

No abstract

The fluorescence quenching mechanism in a highly exothermic region of the Rehm-Weller relationship is shown to be a long-distance electron transfer for producing the geminate radical ion pair with fluorescer radical cation in an electronically excited state and quencher radical anion in the ground state.

No abstract