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arXiv 0705.0651cond-mat.mtrl-scicond-mat.soft
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硫醇盐自组装膜与Ag(111)界面偶极的形成

Dipole Formation at Interfaces of Alkanethiolate Self-assembled Monolayers and Ag(111)

Paul C. Rusu, Gianluca Giovannetti, Geert Brocks

摘要:

用密度泛函理论研究了以-CH $_3$和-CF $_3$为端基的短链硫醇盐在Ag(111)表面自组装单分子膜中界面偶极子的形成.界面偶极子的特征在于通过监测的SAM吸附后的表面功函数的变化。我们比较了具有不同分子堆积密度的结构中SAM的结果,即{ $(\sqrt{7}\times\sqrt{7}) R19.1^{\circ}$ }、{ $(\sqrt{3}\times\sqrt{3}) R30^{\circ}$ }和{p(2 $\times$ 2)}。烷硫醇自组装膜的功函数对银的堆积密度的依赖性较弱,而氟化烷硫醇自组装膜的功函数对银的堆积密度的依赖性较强。结果进行了分析,在两个几乎独立的贡献接口偶极子。这些分别源自分子偶极子和金属表面与分子之间的电荷转移。电荷转移是由银-硫键决定的,与分子的电负性无关。

英文摘要:

The formation of interface dipoles in self-assembled monolayers (SAMs) of --CH$_3$ and --CF$_3$ terminated short-chain alkanethiolates on Ag(111) is studied by means of density functional theory calculations. The interface dipoles are characterized by monitoring the change in the surface work function upon adsorption of the SAM. We compare results obtained for SAMs in structures with a different packing density of molecules, i.e. {$(\sqrt{7}\times\sqrt{7}) R19.1^{\circ}$}, {$(\sqrt{3}\times\sqrt{3}) R30^{\circ}$}, and {p(2$\times$2)}. The work function of alkanethiolate SAMs on silver depends weakly on the packing density; that of fluorinatedalkanethiolates shows a stronger dependance. The results are analyzed in terms of two nearly independent contributions to the interface dipole. These originate respectively from the molecular dipoles and from a charge transfer between the metal surface and the molecules. The charge transfer is determined by the silver--sulfur bond and it is independent of the electronegativity of the molecules.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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