Disentangling enantiosensitivity from dichroism using bichromatic fields

TL;DR

This paper demonstrates how tensorial observables in photoelectron angular distributions from isotropic chiral samples interacting with bichromatic fields can enable chiral discrimination without chiral light, extending previous concepts and deriving new selection rules.

Contribution

It extends the concept of chiral setup to tensorial observables, deriving selection rules for enantiosensitivity and dichroism in photoelectron distributions for various field strengths and phases.

Findings

Identification of enantiosensitive non-dichroic coefficients observable without phase stabilization.

Derivation of selection rules for tensorial observables in bichromatic field interactions.

Explicit expressions for perturbative cases of photoelectron angular distributions.

Abstract

We discuss how tensorial observables, available in photoelectron angular distributions resulting from interaction between isotropic chiral samples and cross polarized $\omega$-$2\omega$ bichromatic fields, allow for chiral discrimination without chiral light and within the electric-dipole approximation. We extend the concept of chiral setup [Phys. Rev. A 98, 063428 (2018)], which explains how chiral discrimination can be achieved in the absence of chiral light, to the case of tensorial observables. We derive selection rules for the enantiosensitivity and dichroism of the $b_{l,m}$ coefficients describing the photoelectron angular distribution valid for both weak and strong fields and for arbitrary $\omega$-$2\omega$ relative phase. Explicit expressions for simple perturbative cases are given. We find that, besides the dichroic non-enantiosensitive [J. Chem. Phys. 151 074106 (2019)], and dichroic-and-enantiosensitive $b_{l,m}$ coefficients found recently [Phys. Rev. A 99, 063406 (2019)], there are also enantiosensitive non-dichroic $b_{l,m}$ coefficients. These reveal the molecular enantiomer independently of the relative phase between the two colors and are therefore observable even in the absence of stabilization of the $\omega$-$2\omega$ relative phase.