Adsorption Behanior of Biomolecule on Slneiconductor and Metal Sunforces.

本文用偏振相关的S K边近边X射线吸收精细结构（NEXAFS）和S Is X射线光电子能谱（XPS）研究了（CH_3）_2S/Ni（100）和（CH_3）_2S/Cu（100）体系。在S K边NEXAFS谱中，亚单层相的偏振依赖性是明显的。NEXAFS结果表明，（CH_3）_2S分子平放在Ni（100）面上，在Cu（100）面上有33°的倾斜角。对于Ni（100）表面，清楚的是表面反应高于Cu（100）表面。含硫氨基分子在金属表面的吸附行为是生物催化和表面反应领域的研究热点。本文利用S Kiedge NEXAFS和XPS技术研究了含硫的L-半胱氨酸氨基酸在多晶Cu、Mo和Ni表面的吸附行为。在NEXAFS谱的第一个特征（1 s-σ（S-C））处可以看到显著的差异。这些结果表明，L-半胱氨酸分子在Ni表面上比在Cu或Mo表面上更活跃。对于Ni吸附体系，电荷从底物转移到L-半胱氨酸分子的硫原子上。

We have studied the (CH_3)_2S/Ni(100) and (CH3)2S/Cu(100) systems using polarization dependent S K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) and S Is X-ray Photoelectron Spectroscopy (XPS) techniques. Polarization dependence was noticeable in the S K-edge NEXAFS spectra for submonolayer phase. The NEXAFS results imply that the (CH_3)_2S molecule is lying flat on the Ni(100) surface and has some tilt angle of 33°on the Cu(100) surface. As for the Ni(lOO) surface, it is cleared that a surface reaction is higher than the Cu(lOO) surface. Adsorption behavior of a sulfur-containing amino molecule on metal surface has been interested in a bio-catalytic and surface reaction fields. In this study, we have studied an adsorption behavior of the L-cysteine amino acid, which contain the sulfur atom, on polycrystalline Cu, Mo and Ni surfaces by S Kiedge NEXAFS and XPS techniques. Noticeable difference can be seen at the first feature (1s-σ(S-C)) of the NEXAFS spectra. Thess results imply that the L-cysteine molecule is more active on the Ni surface in comparison with the Cu or Mo surfaces. It seems that the charge transfer occurs from the substrate to the sulfur atom of the L-cysteine molecule for the Ni adsorption system.