Reactive scattering of a supersonic alkali atom beam: K+HgCl₂, HgBr₂, HgI₂

Abstract

Angular distribution measurements of reactive scattering of a supersonic potassium atom beam by mercuric halide molecules HgX₂ are reported with initial kinetic energies E ∼ 6 kcal mole^-1. All the reactions exhibit stripping dynamics with strong forward peaking in the centre of mass differential cross sections and large total reaction cross sections, Q_r ∼ 150 Ų. However, there is substantial backward peaking ( forward peak) for HgBr₂, HgI₂. A major fraction of the reaction exoergicity is disposed into product vibrational excitation. Just as in the alkali atom-halogen molecule reactions, the reaction dynamics are explained by an electron jump in the entrance valley of the potential surface. However, the dissociation of the HgX₂ ^- ion involves rather different forces from the X₂ ^- ion without having a dramatic effect on the differential reaction cross section.