Local electronic properties at organic-metal interfaces: thiophene derivatives on Pt (III)
Local electronic properties at organic-metal interfaces: thiophene derivatives on Pt (III)
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有机-金属界面的局域电子特性：Pt (III) 上的噻吩衍生物
DOI：
10.1039/c2cp42700a
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
S. Masuda,
中科院分区：
文献类型：
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作者：
H. Sato;S. Ushiyama ;M. Sogo;M. Aoki;K-i. Shudo;T. Sugawara;S. Yanagisawa;Y. Morikawa;S. Masuda,
利用紫外光谱（UPS）和亚稳原子电子能谱（MAES）测定了噻吩（TP）、2-噻吩硫醇（TT）、2,2′-噻吩（BTP）和2,2′-噻吩-5-硫醇（BTT）在Pt（111）上的价电子态，以阐明π共轭效应和取代基效应对有机-金属界面局部电子性质的影响。利用密度泛函理论（DFT）的第一性原理计算对观测到的光谱进行了赋值。TP和BTP在Pt（111）上的化学吸附较弱，而TT和BTT则通过S原子与Pt（111）的S - h键断裂形成硫酸盐。在MAES光谱中，刚好低于费米能级（EF）的弱发射归因于有机物质与Pt（111）之间的轨道混合产生的化学吸收诱导的间隙态（CIGS）。CIGS的形成是在有机-金属界面形成金属结构的原因。在EF处，cigs的相对强度依次为TP（平坦构型）> TT > TP（倾斜构型），表明cigs的空间分布受到有机-金属键强度和吸附几何形状的极大影响。换句话说，TP（平面几何）和TT是金属波函数在EF处扩展的良好介质，这与有机-金属界面上的电荷输运密切相关。
The valence electronic states of thiophene (TP), 2-thiophenethiol (TT), 2,2′-bithiophene (BTP), and 2,2′-bithiophene-5-thiol (BTT) on Pt(111) were measured by ultraviolet photoemission spectroscopy (UPS) and metastable atom electron spectroscopy (MAES) to elucidate how the local electronic properties at the organic–metal interface are altered by the extent of π-conjugation and substituent effects. First-principles calculations using density functional theory (DFT) were used to assign the observed spectra. TP and BTP chemisorb weakly on Pt(111), whereas TT and BTT are strongly bound to Pt(111) through the S atom with the cleavage of the S–H bond, forming a thiolate. In the MAES spectra, weak emission just below the Fermi level (EF) was attributed to a chemisorption-induced gap state (CIGS) produced by orbital mixing between the organic species and Pt(111). The formation of CIGS is responsible for a metallic structure at the organic–metal interface. The relative intensities of CIGSs at EF were in the order of TP (flat-lying configuration) > TT > TP (inclined configuration), indicating that the spatial distribution of CIGSs is drastically altered by the strength of the organic–metal bond and the adsorption geometry. In other words, TP (flat-lying geometry) and TT serve as good mediators of the extension of the metal wave function at EF, which would be closely related to charge transport at organic–metal interfaces.