Quantum control of ro-vibrational dynamics and application to light-induced molecular chirality

TL;DR

This paper develops quantum control schemes to induce chiral vibrational wavepackets in randomly oriented achiral molecules using microwave, IR, and static fields, enabling new spectroscopic methods for light-induced molecular chirality.

Contribution

It introduces novel quantum control protocols for creating chiral vibrational states in achiral molecules, considering full rotational and vibrational quantum dynamics.

Findings

Identified conditions for chiral wavepacket creation in randomly oriented molecules.

Proposed excitation schemes combining microwave, IR, and static fields.

Extended chiral spectroscopy techniques beyond UV regions.

Abstract

Achiral molecules can be made temporarily chiral by excitation with electric fields, in the sense that an average over molecular orientations displays a net chiral signal [Tikhonov et al., Sci. Adv. 8, eade0311 (2022)]. Here, we go beyond the assumption of molecular orientations to remain fixed during the excitation process. Treating both rotations and vibrations quantum mechanically, we identify conditions for the creation of chiral vibrational wavepackets -- with net chiral signals -- in ensembles of achiral molecules which are initially randomly oriented. Based on the analysis of symmetry and controllability, we derive excitation schemes for the creation of chiral wavepackets using a combination of (a) microwave and IR pulses and (b) a static field and a sequence of IR pulses. These protocols leverage quantum rotational dynamics for pump-probe spectroscopy of chiral vibrational dynamics, extending the latter to regions of the electromagnetic spectrum other than the UV.