Creating, imaging, and controlling dynamic chirality induced by molecular rotations

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Chirality is ubiquitous throughout nature and is conventionally associated with a chemical or optical activity of a molecule in either of its two enantiomeric (mirror-image) forms. Since its discovery by Louis Pasteur in 1848, there remain many open questions about the origin of chirality. Notably, the origin of biomolecular (homo)chirality, which is concerned with the bias in the chemistry of life that favours L amino acids and D monosaccharides over the other enantiomeric form, is a controversial and often debated subject.Although usually regarded as a geometric property, chirality can also be dynamically created in “statically” non-chiral molecules through extreme rotational excitation [see A. Owens, A. Yachmenev, and J. Küpper, arXiv:1802.07803 [physics.chem-ph], (2018)].The phenomenon of rotationally induced chirality is closely connected to the effect of rotational energy clustering exhibiting by some polyatomic molecules, such as H2S or PH3, at high rotational excitation.In this project we will perform a joint experimental and theoretical investigation to demonstrate for the first time the effect of rotationally-induced chirality: An optical centrifuge rotationally excites the H2S (CH3D, CH4) molecule into chiral cluster states that correspond to clockwise (R-enantiomer) or anticlockwise (S-enantiomer) rotation about axes almost coinciding with single S—H (C—H) bonds. Application of a strong dc electric field during the centrifuge pulse favours one rotating enantiomeric form over the other, creating dynamically chiral molecules with permanently oriented rotational angular momentum. In the course of this project, we will comprehensively investigate all aspects of dynamic chirality induced by extreme rotational excitations, from creating and imaging through to controlling of its properties.This novel and unexplored research topic promises to offer fresh insights into the phenomenon of rotationally induced chirality in molecular systems. Given the importance of chirality to our understanding of molecular and material behaviour, the ability to create chirality in achiral systems is of great practical interest. On a fundamental level, an improved theoretical understanding of molecular chirality will contribute to our basic knowledge of physical, chemical, and biological processes.