Collisional alignment and molecular rotation control chemi-ionization of individual conformers

Abstract: The relationship between the shape of a molecule and its chemical reactivity is a central tenet in chemistry. However, the influence of the molecular geometry on reactivity can be subtle and result from several opposing effects. Using a novel crossed-molecular-beam experiment in which individual rotational quantum states of specific conformers of a molecule are separated, we study the chemi-ionization reaction of hydroquinone with metastable neon atoms. We show that collision-induced alignment of the reaction partners caused by geometry-dependent long-range forces crucially influences reaction pathways for distinct conformers which is, however, countered by molecular rotation. We demonstrate how the interplay between molecular geometry, chemical steering forces and rotational dynamics govern the outcome of reactions and illustrate the capability of advanced molecule-control techniques to unravel these effects.