Potentiation of the cage effect in binary solvents detected by magnetic modulation of exciplex fluorescence

It was shown that selective solvation potentiates the cage effect in recombination of radical ion pairs formed in electron phototransport in binary solvents with components with strongly differing dielectric properties. This is manifested by a more pronounced (in comparison to single solvents) increase in the exciplex fluorescence in a magnetic field in solutions of pyrene with an excess of N,N-dimethylaniline. The magnitude of the magnetic effect, which is a function of the composition of the solvent, is equal to a maximum of 18% (B= 30 mT) for the benzene/dimethyl sulfoxide binary solvent with a 0.26 volume fraction of the latter. A simple model which explains the results obtained is proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2456–2463, November, 1991.