Geometric fields and new enantio-sensitive observables in photoionization of chiral molecules

Abstract: Chiral molecules are instrumental for molecular recognition in living organisms. Distinguishing between two opposite enantiomers, the mirror twins of the same chiral molecule, is both vital and challenging. Photoelectron circular dichroism (PECD), an extremely sensitive probe of molecular chirality via photoionization, outperforms standard optical methods by many orders of magnitude. Here we show that the physical origin of PECD in chiral molecules is linked to the concept of geometric magnetism, which enables a broad class of phenomena in solids including the anomalous electron velocity, the Hall effect, and related topological phenomena. We uncover the geometric field in molecular photoionization, which leads to a new class of enantio-sensitive observables emerging due to ultrafast excitation of chiral electronic or vibronic currents prior to ionization. Next, we introduce the first member of this new class: enantio-sensitive orientation of chiral molecules via photoionization. This effect opens new routes to both enantio-separation and imaging of chiral dynamics on ultrafast time scales. Our work suggests that geometric fields in photoionization provide the bridge between the two geometrical properties, chirality and topology.