The Journal of Chemical Physics

A magnetic guide to purify radical beams

Jutta Toscano, Chris Rennick, T. P. Softley, Brianna R. Heazlewood

Published Nov 2, 2018• 11 citations

Abstract

Generating a controllable and pure source of molecular free-radicals or open-shell atoms has been one of the primary barriers hindering the detailed study of radical processes in the laboratory. Here, we introduce a novel magnetic guide for the generation of a pure beam of velocity-selected radicals-a tuneable source that will enable the study of radical interactions with exceptional control over the properties of the radical species. Only radicals with a selected velocity are transmitted through the guide; all other components of the incoming beam (radical species traveling at other velocities, precursor molecules, and seed gas) are removed. The guide is composed of four Halbach arrays-hexapolar focusing elements-and two skimming blades. The relative positions of these components can be adjusted to tune the properties of the resulting beam and to optimise transmission for a given velocity. Experimental measurements of Zeeman-decelerated H atoms transmitted through the guide, combined with extensive simulations, show that the magnetic guide removes 99% of H-atoms traveling outside the narrow target velocity range.

DOI: 10.1063/1.5053656

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