Photoreactivity of unsaturated compounds with hydrogen-terminated silicon(111)
Photoreactivity of unsaturated compounds with hydrogen-terminated silicon(111)
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DOI：
10.1021/la9911990
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发表时间：
2000-06-27
期刊：
影响因子：
3.9
通讯作者：
Chidsey, CED
中科院分区：
文献类型：
--
作者：
Cicero, RL;Linford, MR;Chidsey, CED
本文报道了H-Si（111）与分子氧和末端不饱和烃的光反应性。在空气中用波长为350 nm或更短的紫外光照射H-Si（111）会产生氧化硅;波长更长的紫外光不会导致氧化。当H-Si（111）被浸入已脱氧的不饱和烃（1-辛烯、1-十八烯、1-辛炔、苯乙烯和苯乙炔）中时，用汞灯照射会产生分子厚度的致密堆积的烃膜。以前的工作和这里提出的结果表明，H-Si键添加在这些反应中的不饱和键类似于已知的小分子化学的氢化硅烷化反应，并产生共价键合到表面的吸附物。我们目前的光谱证据表明，从终端乙炔产生的膜由连接到表面的乙烯基吸附物。我们建议，所有这些反应发生通过自由基链机制，由波长依赖的光解吸表面氢的UV光。我们还提出了一种方法，在附录中量化表面吸附覆盖使用XPS和椭圆偏振数据。
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.