Scanning tunneling microscopy based on the conductivity of surface adsorbed water. Charge transfer between tip and sample via electrochemistry in a water meniscus or via tunneling
Scanning tunneling microscopy based on the conductivity of surface adsorbed water. Charge transfer between tip and sample via electrochemistry in a water meniscus or via tunneling
复制标题
基于表面吸附水电导率的扫描隧道显微镜。
DOI：
10.1116/1.589126
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发表时间：
1996
影响因子：
1.4
通讯作者：
G. Cevc
中科院分区：
文献类型：
--
作者：
M. Heim;R. Eschrich;A. Hillebrand;H. Knapp;R. Guckenberger;G. Cevc
由于最近发现了分子薄水膜的高电导率，人们可以在扫描隧道显微镜（STM）中研究不良导体甚至亲水绝缘体。尖端接近实验研究了在扫描水覆盖的表面时隧道尖端和样品表面之间是否必须存在永久水弯月面的问题。对于辉光放电的 Pt/C、金和新劈开的云母，我们研究了接近尖端时电流是否持续增加，或者是否可以观察到电流距离行为的跳跃。电流-距离曲线的跳跃表明水弯月面的形成。我们发现，当湿度高于 55% 时，Pt/C 上吸附的水在尖端和样品之间形成水桥的趋势非常高。当尖端缩回时，水桥被拉出数十纳米的长度。在相对湿度高达 75% 的情况下，对黄金没有观察到类似的影响。就云母而言，其中...
Thanks to the recently discovered high conductivity of molecular thin water films one can investigate poor conductors and even hydrophilic insulators in the scanning tunneling microscope (STM). Tip approach experiments have looked into the question of whether a permanent water meniscus between the tunneling tip and sample surface must be present while scanning across a water covered surface. For glow discharged Pt/C, gold and freshly cleaved mica we investigated whether the current increases continuously when approaching the tip or if jumps in the current distance behavior can be observed. Jumps in the current‐distance curves indicate the buildup of a water meniscus. We found that the tendency of adsorbed water on Pt/C to build up a water bridge between tip and sample is very high at humidities above 55%. When the tip was retracted, the water bridge was pulled out to a length of several tens of nanometers. On gold no comparable effects were observed up to 75% relative humidity. In the case of mica, where ...