Strong chiral dichroism in above threshold ionization and ionization rates from locally-chiral light

TL;DR

This paper introduces a novel technique using locally-chiral laser pulses to achieve highly selective and robust chiral discrimination in photoelectron spectra, surpassing conventional methods in sensitivity and applicability.

Contribution

The study develops a new chirality-sensing method with locally-chiral light that significantly enhances chiral discrimination in above-threshold ionization and ionization rates.

Findings

Achieves up to 10% dichroism in ATI spectra

Demonstrates strong correlation between light chirality and observed dichroism

Validates the method across multiple chiral molecules

Abstract

We derive here a new highly selective photoelectron-based chirality-sensing technique that utilizes 'locally-chiral' laser pulses. We show that this approach results in strong chiral discrimination, where the standard forwards/backwards asymmetry of photoelectron circular dichroism (PECD) is lifted. The resulting dichroism is much larger and more robust than conventional PECD, is found in all hemispheres, and is not symmetric or antisymmetric with respect to any symmetry operator. Remarkably, a CD of up to 10% survives in the angularly-integrated above-threshold ionization (ATI) spectra, and of up to 5% in the total ionization rates. We demonstrate these results through ab-initio calculations in the chiral molecules Bromochlorofluoromethane, Limonene, Fenchone, and Camphor. We also explore the parameter-space of the locally-chiral field and show that the observed CD is strongly correlated to the degree of chirality of the light, validating it as a measure for chiral-interaction strengths. Our results pave the way for highly selective probing of ultrafast chirality in ATI, can potentially lead to all-optical enantio-separation, and motivate the use of locally-chiral light for enhancing ultrafast spectroscopies.