A comparative kinetic study of xenon adsorption on a flat Pt(111) and stepped Pt(557) and Pt(112) surfaces
| Autor: | H. R. Siddiqui, Xingcai Guo, J. T. Yates, P. J. Chen |
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| Rok vydání: | 1990 |
| Předmět: | |
| Zdroj: | The Journal of Chemical Physics. 92:7690-7699 |
| ISSN: | 1089-7690 0021-9606 |
| Popis: | The adsorption and desorption kinetics for Xe on three Pt single crystalline surfaces have been measured using threshold temperature programmed desorption measurements. It has been found that the first‐order desorption kinetic parameters at zero coverage for Xe on Pt(111) (E0d =5.73±0.50 kcal/mol; ν0d=1012.5±0.9 s−1) are in excellent agreement with measurements made by a modulated molecular beam method [E0d =5.65±0.35 kcal/mol; ν0d=1012.1 s−1]. The presence of step defect sites of varying density on Pt(557) (1/6 defects) and on Pt(112) (1/3 defects) is shown to have a marked influence on Xe desorption kinetics, producing larger values of E0d≂8.5–8.7 kcal/mol and larger values of ν0d ≂1014 s−1 compared to Pt(111). In addition, for Pt(111), slight attractive Xe–Xe interactions are observed, whereas for Xe adsorption on step sites, repulsive Xe–Xe interactions are observed as the steps fill. Xe adsorption kinetics on Pt(111) at 87 K are consistent with an island growth mechanism. In contrast, on Pt(557) and ... |
| Databáze: | OpenAIRE |
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