Spin polarized enantio-sensitive multipolar photoelectron currents

Abstract: Photoelectron circular dichroism (PECD) manifests as a forward-backward asymmetry of electron emission in the direction orthogonal to the light polarization plane via one-photon ionization of chiral molecules with circularly polarized light. Multi-polar `PECD' currents, i.e., currents resolved along multiple directions, have also been predicted using two mutually-orthogonal linearly polarized light with carrier frequencies $\omega$ and $2\omega$. These currents arise from the interference between the one- and two-photon transitions. Here, we will show that photoelectron spin detection reveals enantio-sensitive multi-polar currents already in the one-photon regime since the two axes can be marked by the photoelectron momentum and spin-detection axis. Specifically, we consider one-photon ionization of an isotropic ensemble of randomly oriented chiral molecules via circularly polarized light and show that the resulting spin-resolved current has three components whose magnitudes are comparable and can be larger than PECD: (i) a spin-polarization vortex in the plane of light polarization that rotates in opposite directions for opposite enantiomers, (ii) either a spin-sink or source in the plane of light polarization for opposite enantiomers, and (iii) a spin analog of photoelectron vortex dichroism (\href{https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.233201}{Phys. Rev. Lett. \textbf{129}, 233201, 2022}) wherein the detected photoelectron spin encodes molecular chirality.