Photoinduced molecular chirality probed by ultrafast resonant X-ray spectroscopy

TL;DR

This paper demonstrates how ultrafast circularly polarized X-ray spectroscopy can detect transient molecular chirality by measuring time-resolved circular dichroism signals, revealing enantiomeric asymmetry during photoinduced chiral transformations.

Contribution

The study introduces a simulation framework for TRCD signals using circularly polarized X-ray probes, applied to formamide to observe photoinduced chiral geometry changes.

Findings

TRCD signals can distinguish chiral geometries in formamide.

Different K-edges provide localized insights into chiral changes.

Ultrafast X-ray spectroscopy reveals transient enantiomer asymmetry.

Abstract

Recently developed circularly polarized X-ray light sources can probe ultrafast chiral electronic and nuclear dynamics through spatially localized resonant core transitions. We present simulations of time-resolved circular dichroism (TRCD) signals given by the difference of left and right circularly polarized X-ray probe transmission following an excitation by a circularly polarized optical pump with variable time delay. Application is made to formamide which is achiral in the ground state and assumes two chiral geometries upon optical excitation to the first valence excited state. Probes resonant with various K-edges (C, N and O) provide different local windows onto the parity breaking geometry change thus revealing enantiomer asymmetry.