Ionic dissociation of CsBr induced by collisions with Hg: molecular-ion formation

The molecular complex formation (CF) reaction Hg+CsBr→HgCs⁺+Br⁻, competitive to the collision-induced dissociation (CID) Hg+CsBr→Hg+Cs⁺+Br⁻ was studied in crossed molecular beams. The rotatable mass-spectrometer detector made it possible to measure the branching ratio CID/CF in the translation energy range between 5.2–7.9 eV, as well as the angular and energy distributions of positive ions. The branching ratio is an order of magnitude greater than for the Xe+CsBr reaction. HgCs⁺ ions were found only to backscatter. A 2D impulsive model shows two distinct reactive geometric configurations, which both lead to backscattering. The key role of the internal molecular motion is also predicted by the impulsive model.