MECHANISM OF SINGLET OXYGEN INTERACTION WITH SOLVENT REMOVING PROHIBITION OF THE RADIATIVE (1)DELTA-G-](3)SIGMA-G- TRANSITION IN OXYGEN

The values of relative O2 (1DELTA(g)) luminescence rate constant (k(r) rel) in thirty-two solvents with ionization potentials IP = 8-11 eV ar e satisfactorily described by a linear dependence of log (k(r)rel/n2) versus IP with a slope of -0.30 eV-1. Singlet oxygen acting as an elec tron acceptor forms a loose exciplex with a partial charge transfer wi th solvents acting as electron donors; CT interactions remove the proh ibition on the radiative 1DELTA(g) --> 3SIGMA(g)- transition in oxygen . In the region IP > 11 eV, the solvents are very poor electron donors at least for strong electron acceptors such as CCl4 and chloroform an d also for as weak an electron acceptor as water a reverse electron tr ansfer should occur from oxygen to the solvent molecule.