A general method for controlling and resolving rotational orientation of molecules in molecule-surface collisions.

Godsi, Oded; Corem, Gefen; Alkoby, Yosef; Cantin, Joshua T; Krems, Roman V; Somers, Mark F; Meyer, Jörg; Kroes, Geert-Jan et al. · Nat Commun · 2017

basic_science · Level V

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Abstract

The outcome of molecule-surface collisions can be modified by pre-aligning the molecule; however, experiments accomplishing this are rare because of the difficulty of preparing molecules in aligned quantum states. Here we present a general solution to this problem based on magnetic manipulation of the rotational magnetic moment of the incident molecule. We apply the technique to the scattering of H<sub>2</sub> from flat and stepped copper surfaces. We demonstrate control of the molecule's initial quantum state, allowing a direct comparison of differences in the stereodynamic scattering from the two surfaces. Our results show that a stepped surface exhibits a much larger dependence of the corrugation of the interaction on the alignment of the molecule than the low-index surface. We also demonstrate an extension of the technique that transforms the set-up into an interferometer, which is sensitive to molecular quantum states both before and after the scattering event.