Molecularly resolved observation of anisotropic intermolecular force in a formate-ion monolayer on a TiO2(110) surface by scanning tunneling microscopy
Molecularly resolved observation of anisotropic intermolecular force in a formate-ion monolayer on a TiO2(110) surface by scanning tunneling microscopy
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DOI：
10.1016/0927-7757(95)03465-x
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发表时间：
1996-04-20
影响因子：
5.2
通讯作者：
Iwasawa, Y
中科院分区：
文献类型：
--
作者：
Onishi, H;Fukui, K;Iwasawa, Y
利用扫描隧道显微镜（STM）在超高真空条件下观察了TiO2（110）表面吸附甲酸离子的扩散动力学。通过用高偏置STM尖端光栅化单层，可以去除所需区域的甲酸离子，而不会损坏衬底。一片未覆盖的底物因此在（2 × 1）甲酸单层中产生。时间分辨STM观测揭示了填充空隙的单个甲酸离子的输运动力学。各向异性迁移速率表明，一排暴露在衬底上的钛离子呈现出一个一维的甲酸盐迁移通道。从动力学上进一步假定了甲酸-甲酸相互作用的显著各向异性；相邻钛行上的甲酸离子之间的排斥力驱动它们迁移，而相邻钛行上的甲酸离子之间的吸引力在调节层上结构中起次要作用。本研究展示了STM图像如何利用在吸附层中制造的纳米尺寸结构的弛豫，记录调节固体表面上吸附层的分子间力的各向异性。
The diffusion kinetics of adsorbed formate ions have been observed on a TiO2 (110) surface by scanning tunneling microscopy (STM) operated under ultrahigh vacuum. Formate ions in a desired area are removed without damage to the substrate, by rastering the monolayer with a high-biased STM tip. A patch of uncovered substrate is thus created in a (2 x 1)-formate monolayer. Time-resolved STM observation reveals the transport kinetics of individual formate ions filling the void. The anisotropic rate of migration suggests that a row of Ti ions exposed on the substrate presents a one-dimensional channel for formate transport. A significant anisotropy in formate-formate interaction is further postulated from the kinetics; a repulsive force between formate ions neighboring on a Ti row drives them to migrate, whereas an attractive force between formates on adjacent Ti-rows plays a secondary role in regulating overlayer structure. The present study shows how STM images document the anisotropy in intermolecular force regulating an adsorbate overlayer on a solid surface, by taking advantage of the relaxation of a nanometer-sized structure fabricated in the overlayer.