A Molecular Perspective on the CISS Effect

Much of the pioneering experimental and theoretical work the chirality induced spin selectivity effect has focussed on spin-dependent conductivity of chiral molecules between electrodes. Although instrumental in the development of our current understanding of the CISS effect, these set-ups are complicated by the interplay of effects arising from the chiral molecule directly and interactions with electrodes. Arguably a simpler set-up, which I will outline in this talk, is to consider photo-excitation induced electron transfer in chiral molecules, where the affect of chirality on electron transport can potentially be probed more directly.



In particular I will describe a theory of how electron spin coherence[1] and spin polarization[2] can be generated in chiral molecular systems in the absence of electrode interfaces. These effects emerge in systems where charge transport is dominated by incoherent hopping, mediated by spin–orbit and electronic exchange couplings. In this talk I will present the theory of these effects, and the general principles we can use to understand chirality induced spin effects in molecular systems. Furthermore, I will outline how chirality induced spin effects could be probed experimentally, and how it can also manifest in charge recombination reactions [3]. These ideas have also recently been employed to show that spin-polarization can lead to enantioselective chemical reactions [4]. Chirality induced spin coherence and polarization effects should appear in many chiral systems, and the ideas I will present have implications for general spin transport phenomena.