  The structure and quantum state of the reactants have a profound impact on
the kinetics and dynamics of chemical reactions. Over the past years,
significant advances have been made in the control and manipulation of
molecules with external electric and magnetic fields in molecular-beam
experiments for investigations of their state-, structure- and energy-specific
chemical reactivity. Whereas studies for neutrals have so far mainly focused on
weak-field-seeking species, we report here progress towards investigating
reactions of strong-field-seeking molecules by introducing a novel
crossed-molecular-beam experiment featuring an electrostatic deflector. The new
setup enables the characterisation of state- and geometry-specific effects in
reactions under single-collision conditions. As a proof of principle, we
present results on the chemi-ionisation reaction of metastable neon atoms with
rotationally state-selected carbonyl sulfide (OCS) molecules and show that the
branching ratio between the Penning and dissociative ionisation pathways
strongly depends on the initial rotational state of OCS.
