Geometric mechanisms enabling spin- and enantio-sensitive observables in one photon ionization of chiral molecules

TL;DR

This paper uncovers geometric mechanisms behind spin- and enantio-sensitive observables in one-photon ionization of chiral molecules, simplifying their description to three fundamental pseudovectors with broad applicability.

Contribution

It introduces a geometric framework based on pseudovectors to describe spin- and enantio-sensitive observables, reducing the complexity of previous models and highlighting their universal geometric origin.

Findings

Identifies two intrinsic and one extrinsic mechanisms for spin- and enantio-sensitive observables.

Shows these observables depend on three fundamental pseudovectors derived from molecular geometry.

Provides compact, intuitive expressions for chiral photoionization observables.

Abstract

We examine spin-resolved photoionization of randomly oriented chiral molecules via circularly polarized light, and revisit earlier predictions of Cherepkov (J. Phys. B: Atom. Mol. Phys. 16, 1543, 1983). We will show that the dynamical origin of spin- and enantio-sensitive observables arise from two intrinsic mechanisms that are quantified by two pseudovectors stemming from the geometric properties of the photoionization dipoles in spin space and in real space, and an extrinsic mechanism which is a directional bias introduced by the well-defined direction of light polarization. These mechanisms arise solely from electric dipole interactions. Consequently, this means that the ten independent parameters that was earlier predicted by Cherepkov to fully describe spin-resolved photoionization of chiral molecules can be reduced as moments of these three pseudovectors. We also find that the molecular pseudoscalars describing the spin- and enantio-sensitive components of the yield can be described by the flux of these pseudovectors through the energy shell, which changes sign upon switching enantiomers. Our results provide compact expressions for these observables which provide an intuitive picture on what determines the strength of these spin- and enantio-sensitive observables. The approach can be readily generalized to photoexcitation, multiphoton processes, and arbitrary field polarizations. Regardless of the specific driving conditions, the resulting spin- and enantio-sensitive observables are still controlled by the same three pseudovectors, underscoring their universal role as the primary generators of chirality-induced spin asymmetries, emphasizing their fundamental geometric origin and the universality of the mechanism identified here.