Chirality Induced Spin Coherence in Electron Transfer Reactions

Abstract: Recently there has been much interest in the chirality induced spin selectivity effect, whereby electron spin polarisation, which is dependent on the molecular chirality, is produced in electrode-molecule electron transfer processes. Naturally, one might consider if a similar effect can be observed in simple molecular charge transfer reactions, for example in light-induced electron transfer from an electron donor to an electron acceptor. In this work we explore the effect of electron transfer on spins in chiral single radicals and chiral radical pairs using Nakajima-Zwanzig theory. In these cases chirality, in conjuction with spin-orbit coupling, does not lead to spin polarisation, but instead the electron transfer generates quantum coherence between spins states. In principle, this chirality induced spin coherence could manifest in a range of experiments, and in particular we demonstrate that the OOP-ESEEM pulse EPR experiment would be able to detect this effect in oriented radical pairs.