Dep. Física, Edificio CIOyN (Campus Espinardo), Universidad de Murcia, E-30100 Murcia, Spain.
Ultramicroscopy. 2010 Jun;110(7):789-800. doi: 10.1016/j.ultramic.2010.01.015. Epub 2010 Feb 4.
The present work proves that when non-contact Dynamic Scanning Force Microscopy (DSFM) is performed in ambient conditions wrong height measurements of heterogeneous samples can be obtained. In some extreme cases even contrast inversion can be observed. Alkanethiol islands on Au (111) have been used as model system, where contrast inversion is observed with different DSFM modes and various data acquisition parameters. To understand this effect, spectroscopy measurements have been used to show that contrast inversion is really a consequence of the differences in the interaction measured between tip and sample on the bare Au substrate and on the alkanethiol islands. We propose that this interaction is mainly induced by liquid necks forming between tip and sample, which is much stronger on the hydrophilic Au substrate than on the hydrophobic alkanethiol islands.
本工作证明，在环境条件下进行非接触动态扫描力显微镜（DSFM）时，可能会得到不均匀样品的错误高度测量值。在某些极端情况下，甚至可能观察到对比度反转。金（111）上的烷硫醇岛被用作模型系统，在不同的 DSFM 模式和各种数据采集参数下观察到对比度反转。为了理解这种效应，我们使用光谱测量表明，对比度反转确实是探针和样品之间在裸露的金衬底和烷硫醇岛上的相互作用测量差异的结果。我们提出，这种相互作用主要是由探针和样品之间形成的液体颈部引起的，在亲水的金衬底上比在疏水性的烷硫醇岛上要强得多。
