Spectroscopic detection of time-odd molecular chirality

Determine which spectroscopic techniques are sensitive to time-odd chirality in isolated molecules and can distinguish it from time-even chirality.

Background

The paper distinguishes time-even (true) chirality from time-odd (false) chirality, whose handedness reverses under time reversal. Although time-odd chirality has been demonstrated in several engineered and solid-state systems, its experimental realization in isolated molecules is described as elusive.

The authors identify the sensitivity of spectroscopic observables to time-odd molecular chirality as unresolved, with the additional requirement that a suitable technique should discriminate dynamical, time-odd chirality from structural, time-even chirality. The paper proposes photoelectron circular dichroism as one possible probe and presents simulations indicating that it can detect purely rotational time-odd chiral dynamics, but the broader question of which spectroscopic techniques possess this sensitivity remains open.

References

It is also an open question which spectroscopic techniques are sensitive to time-odd chirality, ideally discriminating it from its time-even counterpart.

— Chiral rotational dynamics in the molecular frame: Breaking symmetry with angular momentum  (2608.17479 - Blech et al., 18 Aug 2026) in Introduction

Whether it manifests in a physical observable, e.g. through a molecule-fixed transition dipole in a pump--probe scheme, is left for future work.

— Chiral Temporal Structures in Molecular Rotational Dynamics  (2609.37896 - Löhr et al., 29 Sep 2026) in Section 2.2.2, “Solid angle and parallel-transport holonomy”

Fourth, and most importantly, the enantiosensitive observables associated with chiral rotational wavepackets remain to be established.

— Chiral Temporal Structures in Molecular Rotational Dynamics  (2609.37896 - Löhr et al., 29 Sep 2026) in Section 7, “Conclusions and prospects”