BALLISTIC MOTION AND ABSTRACTION IN DIMER DISSOCIATION AT SURFACES - CL-2 ON K

Non-traditional dissociation dynamics at surfaces, with charge transfe r and diabatic motion, is studied for the model system of Cl-2 molecul es impinging on the metal K. Three-dimensional molecular dynamics on s imple but physically reasonable potential-energy surfaces is used to i nvestigate the final fates of the dissociation fragments (Cl, Cl-) of the molecular ion, Cl-2(-), that is formed by electron transfer (harpo oning) to Cl-2 from the K surface. The model study demonstrates that b oth abstraction (emission of neutrals) and ballistic motion can result from dissociative chemisorption. Our qualitative reasoning has strong implications on other chemisorption systems, like O-2 on alkali and o ther metals and halogens on Si, e.g., a proposed explanation for balli stically moving O atoms on Al.