Atomically resolved electronic structure of pyrite {100} surfaces: An experimental and theoretical investigation with implications for reactivity
Atomically resolved electronic structure of pyrite {100} surfaces: An experimental and theoretical investigation with implications for reactivity
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DOI：
10.2138/am-1999-1007
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发表时间：
1999-10
影响因子：
3.1
通讯作者：
K. Rosso;U. Becker;M. Hochella
中科院分区：
文献类型：
--
作者：
K. Rosso;U. Becker;M. Hochella
摘要利用扫描隧道显微镜和能谱研究了超高真空下解理产生的清洁黄铁矿{100}表面的电子结构。表面原子结构的计算和LEED数据支持{100}表面结构，其经历非常小的弛豫，并且可以通过沿着沿着解理的Fe-S键的平面的体结构的简单终止来近似。UPS光谱示出了在约IeV处形成近表面的价带顶部的明确限定的峰。计算出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字符和较少的S 3 p和Fe 3d eg字符。Slab计算预测，表面配位的损失主要导致Fe 3dZ²类表面态进入体带隙。在低偏压STM成像和归一化的单点隧穿光谱中发现了这种表面状态的证据。对表面Fe和S位的LDOS计算表明，最高占据态主要为类3dZ²特征，最低未占据态为Fe 3dZ²-S 3 p混合特征.结果预测，由于悬挂键的表面状态，Fe网站是积极的有利于S2网站的氧化还原与电子供体或受体物种在这个表面上的相互作用。表面氧化还原反应预计涉及这些高能量悬挂键的淬灭，导致新的键和表面物种，改变表面的化学组成。
Abstract Clean pyrite {100} surfaces, generated by cleaving in UHV, were investigated using scanning tunneling microscopy and spectroscopy for the purpose of understanding the electronic structure at the surface. Calculations of the surface atomic structure and LEED data support a {100} surface structure that undergoes very little relaxation and can be approximated by a simple termination of the bulk structure along a plane of cleaved Fe-S bonds. UPS spectra show a well defined peak at ~1 eV forming the top of the valence band for the near surface. Calculated densities of states for the bulk crystal suggest that this band is comprised primarily of non-bonding Fe 3d t2g character and lesser S 3p and Fe 3d eg character. Slab calculations predict that the loss of coordination at the surface results primarily in the displacement of Fe 3dZ²-like surface states into the bulk band gap. Evidence for this surface state is found in low bias STM imaging and normalized single-point tunneling spectra. Calculations of the LDOS at surface Fe and S sites indicate that the highest occupied state is primarily of 3dZ²-like character and the lowest unoccupied state is of mixed Fe 3dZ²-S 3p character. The results predict that due to the dangling bond surface states, Fe sites are energetically favored over S2 sites for redox interaction with electron donors or acceptor species on this surface. Surface redox reactions are expected to involve the quenching of these high energy dangling bonds, leading to new bonds and surface species, changing the chemical makeup of the surface.