Orientation in molecule-surface interactions

The role of the orientation of a molecule in its interaction with a surface is examined for a number of cases. At first the determination of the static orientation of a molecule at the surface is discussed. A dependence of the orientation on state and coverage is found for O₂ molecules adsorbed on Ag(110). The orientation dependence of NO in chemisorption, displacement reactions, and chemical reactions is discussed. Rotational excitation of NO in collisions with surfaces is shown to exhibit a strong orientation dependence. Dissociative chemisorption of hydrogen molecules is found to depend on the initial orientation of the molecule. Finally, in dissociative collisions of fast molecules with surfaces the role of the initial orientation is examined and the final orientation of the molecular axis is determined. Several mechanisms for molecular dissociation are discussed.