Reactive scattering of alkali dimers: K2 + HgCl2, HgBr2, HgI2

Angular distribution measurements of KX reactive scattering of a potassium dimer K 2 beam by mercuric halide molecules HgX 2 are reported. All the reactions exhibit strong forward peaking in the centre of mass differential cross sections and large total reaction cross sections Q r ∼ 150 Å 2 . However, there is substantial backward peaking ( forward peak) for HgBr 2 , HgI 2 . Despite the direct stripping dynamics, both alkali atoms of the K 2 dimer become bound alkali halide molecules in most (perhaps all) reactive collisions. A major fraction of the reaction exoergicity is disposed into vibrational excitation of the product KX molecules. A mechanism involving a first electron jump in the entrance valley and a second electron jump in the exit valley of the potential surface is suggested to explain the rapid transfer of both K 2 valence electrons.