Gold-sulfur bonding in 2D and 3D self-assembled monolayers: XPS characterization
Gold-sulfur bonding in 2D and 3D self-assembled monolayers: XPS characterization
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DOI：
10.1021/jp9935337
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发表时间：
2000-07-20
影响因子：
3.3
通讯作者：
Lennox, RB
中科院分区：
文献类型：
--
作者：
Bourg, MC;Badia, A;Lennox, RB
尽管人们对平面金 (2D SAM) 和金纳米颗粒 (3D SAM) 上的烷基硫醇自组装单层 (SAM) 进行了深入研究，但 Au-S 键合的实际性质仍然知之甚少。 2D 和 3D SAM 与“参考”Au(I) 配合物（有时称为 Au(I) 硫醇盐聚合物）的 X 射线光电子能谱 (XPS) 光谱的比较，提供了对此问题的详细见解。我们报告了 2D SAM、3D SAM 以及两种短链硫醇（n-C4SH 和 n-C5SH）的 Au(I) 硫醇复合物中的高分辨率 XPS 光谱以及 Au 4f(7/2) 和 S 2p(3/2) 结合能 (BE)。硫 2p(3/2) BE 位移用于比较 SAM 系统和 Au(I) 配合物中的不同键合状态，并确定 SAM 系统中的 S 原子带有约 0.2e 的电荷。 2D 和 3D SAM 表现出相似的 XPS 特性，并且都与 Au(I) 配合物有区别。观察到的 BE 值的起源在金底物的性质和化学吸附的硫原子的氧化态的背景下进行了讨论。 C-13 NMR 化学位移数据和 XPS BE 数据的比较进一步阐明了表面相互作用的性质以及 Au(I) 配合物作为参考材料的用途。
Although self-assembled monolayers (SAMs) of alkylthiols on planar gold (2D SAMs) and on gold nanoparticles (3D SAMs) have been intensely studied, the actual nature of the Au-S bonding remains poorly characterized. Comparison of the X-ray photoelectron spectroscopy (XPS) spectra of 2D and 3D SAMs and "reference" Au(I) complexes, sometimes referred to as Au(I) thiolate polymers, provides detailed insight into this problem. We report high-resolution XPS spectra and Au 4f(7/2) and S 2p(3/2) binding energies (BE) in 2D SAMs, 3D SAMs and the Au(I) thiolate complexes for two short-chain thiols (n-C4SH and n-C5SH). Sulfur 2p(3/2) BE shifts are used to compare the different states of bonding in the SAM systems and the Au(I) complexes and establish that the S atom in the SAM systems bears a charge of about 0.2e. The 2D and 3D SAMs exhibit similar XPS characteristics and are both distinguishable from the Au(I) complexes. The origins of the observed BE values are discussed in the context of the nature of the gold substrate and the oxidation state of the chemisorbed sulfur atom. Comparison of C-13 NMR chemical shift data and XPS BE data further clarifies the nature of the surface interactions as well as the use of the Au(I) complexes as reference materials.