Solvent Radical Anions in Irradiated Aliphatic Ketones and Esters as Observed Using Time-Resolved Magnetic Field Effects in the Recombination Fluorescence

It has been found that addition of alcohols (~0.1 M) to some liquid ketones and esters results in well-pronounced oscillations in the decay of the delayed fluorescence intensity from irradiated solutions. The analysis of the time-resolved magnetic field effects (TR MFEs) in the recombination fluorescence has shown that these oscillations are a manifestation of singlet-triplet transitions in spin-correlated radical ion pairs (RIPs) created by irradiation. Comparison with literature data indicates that the transitions are due to hyperfine couplings (HFCs) in the solvent radical anion (RA), stabilized due to the presence of alcohol molecules. In acetone, this stabilization effect has been observed for methanol, ethanol, 2- propanol, and, to a smaller extent, for