FACETING INDUCED BY ULTRATHIN METAL FILMS ON W(111) AND Mo(111): STRUCTURE, REACTIVITY, AND ELECTRONIC PROPERTIES
FACETING INDUCED BY ULTRATHIN METAL FILMS ON W(111) AND Mo(111): STRUCTURE, REACTIVITY, AND ELECTRONIC PROPERTIES
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W(111) 和 Mo(111) 上超薄金属膜引起的刻面：结构、反应性和电子性能
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
R. A. Campbell
中科院分区：
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作者：
T. Madey;J. Guan;C. Nien;C. Dong;H.;R. A. Campbell
我们利用俄歇谱、LEED、热脱附谱和扫描隧道显微镜研究了过渡金属和贵金属在Mo（111）和W（111）衬底上的外延膜。原子级粗糙、开放的bcc（111）表面在被某些金属的≥ 1个单层厚度的膜覆盖时在形态上是不稳定的，即它们形成小面结构。例如，使用UHV STM研究Pd/W（111），我们发现Pd覆盖的W（111）表面在退火后完全变成三面{211}棱锥，对于Pd覆盖度大于临界覆盖度θc。当W（111）或Mo（111）表面掺杂Pt、Au、Ir、Rh、氧或硫时，也会形成锥形小面。相反，Ti、Co、Ni、Cu、Ag和Gd的单层膜在W（111）和Mo（111）表面上不诱导大量重构或小面化。刻面似乎是驱动的，但动力学限制：刻面是由增加的各向异性的表面自由能，发生的膜-co…
We have studied ultrathin films of transition and noble metals on Mo(111) and W(111) using Auger spectroscopy, LEED, thermal desorption spectroscopy (TDS) and scanning tunneling microscopy (STM). The atomically rough, open bcc(111) surfaces are morphologically unstable when covered by films ≥ 1 monolayer thick of certain metals, i.e. they form faceted structures. For example, using a UHV STM to study Pd/W(111), we find that the Pd-covered W(111) surface becomes completely faceted to three-sided {211} pyramids upon annealing, for Pd coverages greater than a critical coverage θc. Formation of pyramidal facets also occurs when W(111) or Mo(111) surfaces are dosed with Pt, Au, Ir, Rh, oxygen or sulfur. In contrast, monolayer films of Ti, Co, Ni, Cu, Ag and Gd do not induce massive reconstruction or faceting on W(111) and Mo(111) surfaces. The faceting appears to be thermodynamically driven but kinetically limited: faceting is caused by an increased anisotropy in surface free energy that occurs for the film-co...