Enantiosensitive locking of photoelectron spin and cation orientation

Abstract: When electrons pass through chiral molecules, their transmission is strongly influenced by the orientation of their spin: molecules with opposite handedness preferentially transmit electrons with oppositely aligned spins. The underlying nature of this striking phenomenon, known as chirality-induced spin selectivity (CISS), remains controversial: its observed strength far surpasses predictions based on the typically weak spin-orbit interaction. A significant fraction of CISS phenomena are driven by light, and thus could be controlled at the ultrafast scale, and impact chemical change following photoionization or photoexcitation. To date, most studies of spin-selective enantio-sensitive photodynamics have concentrated on the influence of the magnetic field component of light. Here, we establish dynamical and geometric mechanisms of spin-selective photo-induced dynamics that arise purely from electric dipole interactions. Using one-photon ionization as an example, we report a new effect: enantio-sensitive locking of molecular cation orientation to the spins of the photoelectron and the hole in the parent molecule. One-photon ionization is an ubiquitous process, where CISS has already been found in oriented samples. Remarkably, the new effect that we report here emerges upon photoionization of randomly oriented chiral molecules, establishing CISS in amorphous chiral media.