Dri C, Africh C, Esch F, Comelli G, Dubay O, Köhler L, Mittendorfer F, Kresse G, Dudin P, Kiskinova M
Department of Physics, University of Trieste, I-34127 Trieste, Italy.
J Chem Phys. 2006 Sep 7;125(9):094701. doi: 10.1063/1.2345058.
The initial oxidation of the Rh(110) surface was studied by scanning tunneling microscopy, core level spectroscopy, and density functional theory. The experiments were carried out exposing the Rh(110) surface to molecular or atomic oxygen at temperatures in the 500-700 K range. In molecular oxygen ambient, the oxidation terminates at oxygen coverage close to a monolayer with the formation of alternating islands of the (10x2) one-dimensional surface oxide and (2x1)p2mg adsorption phases. The use of atomic oxygen facilitates further oxidation until a structure with a c(2x4) periodicity develops. The experimental and theoretical results reveal that the c(2x4) structure is a "surface oxide" very similar to the hexagonal O-Rh-O trilayer structures formed on the Rh(111) and Rh(100) substrates. Some of the experimentally found adsorption phases appear unstable in the phase diagram predicted by thermodynamics, which might reflect kinetic hindrance. The structural details, core level spectra, and stability of the surface oxides formed on the three basal planes are compared with those of the bulk RhO2 and Rh2O3.
通过扫描隧道显微镜、芯能级光谱和密度泛函理论研究了Rh(110)表面的初始氧化过程。实验是在500-700 K温度范围内将Rh(110)表面暴露于分子氧或原子氧中进行的。在分子氧环境中，氧化在接近单层的氧覆盖度时终止，形成(10x2)一维表面氧化物和(2x1)p2mg吸附相的交替岛状结构。使用原子氧有助于进一步氧化，直到形成具有c(2x4)周期性的结构。实验和理论结果表明，c(2x4)结构是一种“表面氧化物”，与在Rh(111)和Rh(100)衬底上形成的六边形O-Rh-O三层结构非常相似。一些实验发现的吸附相在热力学预测的相图中似乎不稳定，这可能反映了动力学阻碍。将在三个基面形成的表面氧化物的结构细节、芯能级光谱和稳定性与块状RhO2和Rh2O3的进行了比较。
