TEMPERATURE STUDY OF THE MAGNETIC-FIELD EFFECT IN PHOTOGENERATED FLEXIBLY LINKED RADICAL ION-PAIRS - INFLUENCE OF THE STOCHASTICALLY MODULATED EXCHANGE INTERACTION

Experimentally observed temperature-dependent shifts in magnetic-field-dependent reaction yield spectra of polymethylene-linked radical ion pairs are correlated with motional shifts in calculated spin-exchange spectra. The compounds investigated are pyrene-(CH2)n-N,N-dimethylaniline, n less-than-or-equal-to 16, in the polar solvent acetonitrile. Radical ion pairs have been generated by photoinduced intramolecular electron transfer. The magnetic field effect (MFE) was monitored with optical methods: both absorption and emission spectroscopy. The MFE is explained and discussed with the help of qualitative diagrams that provide an integrated picture of the combination of spin dynamics and molecular dynamics. A through-space (solvent) exchange interaction is assumed in our discussions.