Chiral rotational dynamics in the molecular frame: Breaking symmetry with angular momentum

Abstract

Achiral molecules can be prepared in superposition states that are chiral. Here, we propose angular momentum orientation in the molecular frame to achieve the required symmetry breaking, exerting rotational control without the need for laboratory frame orientation. We derive the conditions for chiral rotational dynamics from the requirement to simultaneously break the continuous spatial rotational symmetry and the molecular point group symmetry. This can be achieved by three microwave pulses as well as two non-resonant optical pulses in combination with a THz pulse or three THz pulses, all with mutually orthogonal polarization directions, and the ensuing dynamics can be probed by photoelectron circular dichroism. Our results open the way for distinguishing structural from dynamical enantioselectivity and investigating time-odd chiroptical phenomena in randomly oriented molecules.