Chirality Induced Spin Coherence in Electron Transfer Reactions

TL;DR

This paper investigates how molecular chirality influences electron spin coherence during charge transfer reactions, revealing that chirality induces quantum coherence between spin states rather than spin polarization, with potential experimental detection methods discussed.

Contribution

It introduces the concept that chirality, combined with spin-orbit coupling, generates spin coherence in electron transfer, expanding understanding beyond spin polarization effects.

Findings

Chirality induces spin coherence, not polarization, in electron transfer.

Quantum coherence between spin states can be generated by chiral molecules.

OOP-ESEEM pulse EPR can detect chirality-induced spin coherence.

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.