AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS3-WeM

Paper SS3-WeM5
Sticking Probability Measurement of Oriented NO on Al(111)

Wednesday, October 4, 2000, 9:40 am, Room 210

Session: Gas/Surface Dynamics
Presenter: A.J. Komrowski, University of California, San Diego
Authors: A.J. Komrowski, University of California, San Diego
B. Berenbak, FOM Institute AMOLF, The Netherlands
S. Stolte, Vrije Universiteit Amsterdam, The Netherlands
A.W. Kleyn, Leiden University, The Netherlands
A.C. Kummel, University of California, San Diego
Correspondent: Click to Email
We report that by controlling the reactant orientation immediately prior to the interaction, we have gained new insight into the dissociative and abstractive chemisorption of NO interacting with a reactive metal surface, Al(111). In a novel experiment, we have used the beam reflectivity technique to measure the sticking probability of an oriented molecular beam as a function of incident molecular orientation and translational energy. We observe a higher sticking probability when the N-end is preferentially directed towards the Al(111) surface. The difference in sticking probabilities between N-end first and O-end first interactions increases with increasing incident translational energy. In contrast, Auger spectroscopy results from non-oriented molecular beams of NO with similar energies show initial surface coverage Nitrogen/ Oxygen ratios less than unity. The results are consistent with a two step chemisorption process for the initial reaction with the clean surface. First, an electron harpoons from the metal to the N-end of the molecule. The NO@super -@ molecular ion is attracted to the surface by its image charge. Second, the molecule may absorb another electron from the surface before the intramolecular bond breaks and Oxygen is deposited onto the surface while Nitrogen is ejected into the gas phase.