Fig. 1: Experimental set-up.
From: Strong inverse kinetic isotope effect observed in ammonia charge exchange reactions
a Coulomb crystals are formed when trapped \({{\rm{Ca}}}^{+}\) ions are laser cooled. The lattice positions of the constantly fluorescing \({{\rm{Ca}}}^{+}\) ions can be directly observed by a charge-coupled device (CCD) camera, with the presence of other co-trapped species inferred from changes to the \({{\rm{Ca}}}^{+}\) fluorescence pattern. Time-of-flight (ToF) traces are recorded by ejecting the ions from the trap and onto a multichannel plate (MCP) detector. See the “Methods” section for further details. b Experimental images of mono-component (\({{\rm{Ca}}}^{+}\)-only, left), bi-component (\({{\rm{Ca}}}^{+}\) and \({{\rm{Xe}}}^{+}\), centre) and tri-component (\({{\rm{Ca}}}^{+}\), \({{\rm{Xe}}}^{+}\), and \({{\rm{NH}}}_{3}^{+}\), right) Coulomb crystals, showing the progress of the charge exchange reaction. c False-colour image of a simulated tri-component Coulomb crystal, illustrating the locations of the non-fluorescing \({{\rm{NH}}}_{3}^{+}\) and \({{\rm{Xe}}}^{+}\) ions in addition to the \({{\rm{Ca}}}^{+}\) ions. See Supplementary Note 3 for details on the simulations.
