The Electronic Structure and Reactivity of Sulfide Surfaces: Combining Atomic-Scale Observations with Theoretical Calculations
The Electronic Structure and Reactivity of Sulfide Surfaces: Combining Atomic-Scale Observations with Theoretical Calculations
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发表时间：
1998-06
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通讯作者：
K. Rosso
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作者：
K. Rosso
为了了解硫化物表面反应性的本质，在超高真空（UHV）下研究了清洁黄铁矿{100}和铜蓝{001}表面的电子结构。使用主要的扫描隧道显微镜和光谱（STM/STS），在这些表面上的原子位点的电子结构直接探测，并通过从头计算提供的结果的化学见解。黄铁矿是地球近地表最丰富的硫化物。它的氧化影响着各种各样的自然和工业化学过程，但对所涉及的分步氧化反应知之甚少。出于这个原因，前两章是针对了解表面的电子结构和黄铁矿表面的基本反应在原子尺度。UPS光谱显示在~ 1 eV处的特征峰形成近表面的价带顶部。从头计算的散装晶体的状态密度表明，这条带主要是由非键合的Fe 3d t2 g和较少的S 3 p和Fe 3d eg状态。从头计算预测，在表面的破键对称性取代Fe 3dz 2悬空键状态到体带隙。在低偏置STM成像和归一化单点隧穿光谱中发现了证实这种表面态存在的证据，这些证据与表面Fe和S位点处的LDOS的计算结果非常一致。结果预测，由于悬挂键的表面状态，铁网站是积极的有利于与电子供体或受体物种的氧化还原相互作用。STM/STS观察结果
The electronic structure of clean pyrite {100} and covellite {001} surfaces have been investigated in ultra-high vacuum (UHV) for the purpose of understanding the nature of sulfide surface reactivity. Using primarily scanning tunneling microscopy and spectroscopy (STM/STS), the electronic structure at atomic sites on these surfaces was directly probed, and chemical insight into the results was provided by ab-initio calculations. Pyrite is the most abundant sulfide at the earth’s near surface. Its oxidation influences a wide variety of natural and industrial chemical process, but very little is known about the stepwise oxidation reactions involved. For this reason, the first two chapters are directed at understanding the surface electronic structure and fundamental reactivity of pyrite surfaces at the atomic scale. UPS spectra show a characteristic peak at ~ 1 eV forming the top of the valence band for the near surface. Ab-initio calculated densities of states for the bulk crystal suggest that this band is comprised primarily of non-bonding Fe 3d t2g and lesser S 3p and Fe 3d eg states. Ab-initio slab calculations predict that the broken bonding symmetry at the surface displaces a Fe 3dz2 dangling bond state into the bulk band gap. Evidence confirming the presence of this surface state is found in low bias STM imaging and normalized single-point tunneling spectra, which are in remarkable agreement with calculations of the LDOS at surface Fe and S sites. The results predict that due to the dangling bond surface states, Fe sites are energetically favored for redox interaction with electron donors or acceptor species. STM/STS observations of