Water Diffusion and Clustering on Pd(111)
Water Diffusion and Clustering on Pd(111)
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DOI：
10.1126/science.1075095
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发表时间：
2002-09
期刊：
影响因子：
56.9
通讯作者：
T. Mitsui;M. K. Rose;E. Fomin;D. Ogletree;Miquel Salmeron
中科院分区：
文献类型：
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作者：
T. Mitsui;M. K. Rose;E. Fomin;D. Ogletree;Miquel Salmeron
用扫描隧道显微镜研究了水分子在Pd（111）表面的吸附、扩散和聚集。在40开尔文时，低覆盖率的水以孤立分子的形式吸附，这些分子通过跳跃到最近的相邻位置而扩散。碰撞后，它们首先形成二聚体，然后形成三聚体，四聚体，等等。当二聚体，三聚体和四聚体形成时，这些物种的迁移率增加了几个数量级，当团簇包含五个或更多分子时，这些物种的迁移率再次下降。发现环状六聚体特别稳定。它们随着进一步的暴露而生长，以形成相对于Pd（111）衬底的相称的六边形蜂窝结构。这些观察结果说明了分子间氢键和分子-基底键之间的相对强度的变化作为水簇大小的函数，这是决定材料润湿性能的关键属性。
The adsorption, diffusion, and clustering of water molecules on a Pd(111) surface were studied by scanning tunneling microscopy. At 40 kelvin, low-coverage water adsorbs in the form of isolated molecules, which diffuse by hopping to nearest neighbor sites. Upon collision, they form first dimers, then trimers, tetramers, and so on. The mobility of these species increased by several orders of magnitude when dimers, trimers, and tetramers formed, and decreased again when the cluster contained five or more molecules. Cyclic hexamers were found to be particularly stable. They grow with further exposure to form a commensurate hexagonal honeycomb structure relative to the Pd(111) substrate. These observations illustrate the change in relative strength between intermolecular hydrogen bonds and molecule-substrate bonds as a function of water cluster size, the key property that determines the wetting properties of materials.