| Autor: |
Christopher J. Baddeley, A. Wander, Richard M. Lambert, R. M. Ormerod, C.J. Barnes, D.A. King |
| Rok vydání: |
1994 |
| Předmět: |
|
| Zdroj: |
Surface Science. 314:1-12 |
| ISSN: |
0039-6028 |
| DOI: |
10.1016/0039-6028(94)90208-9 |
| Popis: |
Automated Tensor LEED has been used to determine the detailed crystallography of structures formed during Pd deposition on Au{111}. At 200 K, deposition of 0.2 monolayer Pd results in a complete lifting of the clean surface Au{111} reconstruction, with excess Au atoms being squeezed into a disordered adlayer with the added Pd adatoms. At monolayer coverage at this temperature a disordered structure is formed, which orders on heating to 300 K to a (1 × 1) structure with a predominantly Pd top layer. Further deposition of Pd produces a disordered overlayer. On annealing to ⩾ 500 K, this converts to an ordered alloy structure with (3×3)R30° periodicity. This structure consists of at least 2 layers of Pd2Au alloy. It is unique in showing a constant splitting of all Bragg beams, attributed to facetting into domains oriented only 0.75° from the planar Au{111} surface. This rumpled structure possesses domains which are larger than 100 A in width. The results are discussed in relation to the known catalytic activity for the various structures in the cyclisation of ethyne to benzene. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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