Formation of Two-Dimensional Copper Selenide on Cu(111) at Very Low Selenium Coverage

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• 作者：Dr. Holly Walen ; Dr. Da-Jiang Liu ; Dr. Junepyo Oh ; Dr. Hyun Jin Yang ; Dr. Yousoo Kim and Prof. Patricia A. Thiel
• 刊名：ChemPhysChem
• 出版年：2016
• 出版时间：July 18, 2016
• 年：2016
• 卷：17
• 期：14
• 页码：2137-2145
• 全文大小：2745K
• ISSN：1439-7641

文摘

Using scanning tunneling microscopy (STM), we observed that adsorption of Se on Cu(111) produced islands with a (√3×√3)R30° structure at Se coverages far below the structure's ideal coverage of 1/3 monolayer. On the basis of density functional theory (DFT), these islands cannot form due to attractive interactions between chemisorbed Se atoms. DFT showed that incorporating Cu atoms into the √3-Se lattice stabilizes the structure, which provided a plausible explanation for the experimental observations. STM revealed three types of √3 textures. We assigned two of these as two-dimensional layers of strained CuSe, analogous to dense planes of bulk klockmannite (CuSe). Klockmannite has a bulk lattice constant that is 11 % shorter than √3 times the surface lattice constant of Cu(111). This offers a rationale for the differences observed between these textures, for which strain limits the island size or distorts the √3 lattice. STM showed that existing step edges adsorb Se and facet toward ⟨1pan data-equation-construct="true" class="math-equation-construct">pan data-equation-image="true" class="math-equation-image">pan>pan data-equation-mathml="true" class="math-equation-mathml" style="display:none">2‾pan>pan> 1⟩, which is consistent with DFT.