| Autor: |
Cicero, R. L., Linford, M. R., Chidsey, C. E. D. |
| Zdroj: |
Langmuir; June 2000, Vol. 16 Issue: 13 p5688-5695, 8p |
| Abstrakt: |
We report the photoreactivity of H−Si(111) with dioxygen and terminally unsaturated hydrocarbons. Illumination of H−Si(111) in air with ultraviolet light of wavelength of 350 nm or shorter produces oxidized silicon; longer wavelengths cause no oxidation. When H−Si(111) is immersed in unsaturated hydrocarbons (1-octene, 1-octadecene, 1-octyne, styrene, and phenylacetylene) that have been deoxygenated, illumination with a Hg lamp results in densely packed hydrocarbon films of molecular thickness. Previous work and the results presented here suggest that the H−Si bond adds across the unsaturated bond in these reactions similar to hydrosilylation reactions known for small-molecule chemistry and produce adsorbates covalently bonded to the surface. We present spectroscopic evidence showing films resulting from terminal acetylenes consist of adsorbates linked to the surface by a vinyl group. We propose that all of these reactions occur through a radical-chain mechanism initiated by the wavelength-dependent photodesorption of surface hydrogen by UV light. We also present a method in the Appendix to quantify surface adsorbate coverage using XPS and ellipsometric data. |
| Databáze: |
Supplemental Index |
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