Evidence for 'Inclined' CO on Pd(210).
Abstract
The ESDIAD method (Electon Stimulated Desorption Ion Angular Distributions) has been used to verify an unusual bonding configuration for CO adsorbed on the rather open Pd(210) surface. In a previous infrared reflection-adsorption study of CO on Pd(210) (where top layer atoms with the nearest neighbor distance of 2.73 A do not exist) the results indicated that CO was bridge-bonded to two Pd atoms via the carbon atom. Such bridge-bonding can only occur in several distinct sites between atoms in the first and second atom layers, so that the axes of absorbed CO molecules are expected to be inclined away from the normal by approx. 18 deg. The ESDIAD data are consistent with the infrared observations at low coverages (two-fold symmetric triangular ESDIAD patterns dominated by off-normal ion emission in appropriate symmetry directions), but the results are more complex at higher coverages. At the saturation CO coverage at 90 K, the data indicate that CO is bonded normal to the surface. The relative yields of O(+) and CO(+) ions are sensitive to the bonding mode, with O(+) alone seen for bridge-bonded CO at low coverages and both O+ and CO(+) ions observed at higher coverages. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1979
- Accession Number
- ADA068192
Entities
People
- A. M. Bradshaw
- F. M. Hoffmann
- John Yates
- Theodore E. Madey
Organizations
- National Institute of Standards and Technology