Probing molecular chirality via laser-induced electronic fluxes

TL;DR

This study investigates how ultrafast laser pulses can control and modify molecular chirality during electronic motion, revealing that external fields and molecular orientation critically influence chiral charge migration.

Contribution

It demonstrates the conditions under which laser-induced electric fields can break or preserve molecular chirality during ultrafast charge migration in enantiomers.

Findings

Chirality breaking fields are only effective in oriented molecules.

Charge migration remains chiral when the laser polarization is in the mirror plane or perpendicular.

Mirror symmetry presence or absence in the external field determines chiral properties.

Abstract

Chirality is ubiquitous in nature and of fundamental importance in science. The present work focuses on understanding the conditions required to modify the chirality during ultrafast electronic motion by bringing enantiomers out-of-equilibrium. Different kinds of ultrashort linearly-polarised laser pulses are used to drive an ultrafast charge migration process by the excitation of a small number of low-lying excited states from the ground electronic state of S- and R-epoxypropane. Control over chiral electron dynamics is achieved by choosing the different orientations of the linearly polarised pulse. We find that chirality breaking electric fields are only possible in oriented molecules, and that charge migration remains chiral when the polarisation of the field lies in the mirror plane defining the enantiomer pair, or when it is strictly perpendicular to it. Ultimately, the presence or the absence of a mirror symmetry for the enantiomer pair in the external field determines the chiral properties of the charge migration process.