Electron Spin Polarization of Radical Pairs in Simple Molecular Wires

Abstract

The density vector approach as developed for chemically induced dynamic electron polarization (CIDEP) has been extended to transient radicals produced by flash photolysis in molecular wire polymers that exhibit reversible electron transfer. Unique electron spin polarization (ESP) arising from the hyperfine structure is predicted for reversible electron transfer in molecular wires. A radical pair consisting of one stationary radical and one radical reversibly migrating in a polymer is used to explain the difference in CIDEP in normal solution versus CIDEP in reversible molecular wires. Balanced anti-phase ESP is predicted as electron spins transfer forward, where forward refers to increasing the distance between the members of the radical pair. However, unbalanced antiphase ESP is predicted when electrons transfer back to certain previous positions. The unusual, unbalanced antiphase spectral lines originate because the electron spin migration is confined to a single polymer molecule. If electron spins were...