| Autor: |
Chi Ming Chan, C.-T. Kao, Gabor A. Somorjai, G. S. Blackman, M. A. Van Hove |
| Rok vydání: |
1989 |
| Předmět: |
|
| Zdroj: |
Surface Science. 224:77-96 |
| ISSN: |
0039-6028 |
| DOI: |
10.1016/0039-6028(89)90902-3 |
| Popis: |
The surface structure and chemical reactivity of nitric oxide on Rh(111) has been studied over the temperature range of 120–480 K by high-resolution electron energy loss spectroscopy (HREELS) and dynamical low-energy electron diffraction (LEED) analysis. HREELS results indicate that the adsorption sites of NO depend strongly on the surface coverage and adsorption temperature. At one-half monolayer coverage a c(4 × 2) LEED pattern is observed, with only bridge sites occupied (NO stretching frequency of 1590 cm−1). At saturation coverage and 120 K, only disordered bridge-site adsorption is observed (NO stretching frequency of 1635 cm−1). Saturation adsorption at a surface temperature between 250 and 350 K leads to NO occupation of top sites (v(NO) = 1830 cm−1) in addition to bridge sites (v(NO) = 1515 cm−1), in an ordered (2 × 2) lattice. A dynamical LEED intensity analysis of the (2 × 2) structure shows that each unit cell contains two molecules in near-top-sites and one in a bridge site. All the NO molecules are perpendicular to the surface with bond lengths of 1.15 A. The RhN bond length is 2.07 A at the near-top site and 2.05 A at the bridge site. The NO surface structure is similar to a previously analyzed (2 × 2) structure at high CO coverage. This is the first LEED structural analysis for a pure molecular NO overlayer on a metal single crystal surface. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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