Department of Physics, Faculty of Science, McGill University, Montreal, Canada.
Nanotechnology. 2012 Aug 24;23(33):335702. doi: 10.1088/0957-4484/23/33/335702. Epub 2012 Aug 3.
The field ion microscope (FIM) can be used to characterize the atomic configuration of the apices of sharp tips. These tips are well suited for scanning probe microscope (SPM) use since they predetermine the SPM resolution and the electronic structure for spectroscopy. A protocol is proposed for preserving the atomic structure of the tip apex from etching due to gas impurities during the period of transfer from the FIM to the SPM, and estimations are made regarding the time limitations of such an experiment due to contamination with ultra-high vacuum rest gases. While avoiding any current setpoint overshoot to preserve the tip integrity, we present results from approaches of atomically defined tungsten tips to the tunneling regime with Au(111), HOPG (highly oriented pyrolytic graphite) and Si(111) surfaces at room temperature. We conclude from these experiments that adatom mobility and physisorbed gas on the sample surface limit the choice of surfaces for which the tip integrity is preserved in tunneling experiments at room temperature. The atomic structure of FIM tip apices is unchanged only after tunneling to the highly reactive Si(111) surface.
场离子显微镜（FIM）可用于表征尖锐针尖的顶点的原子结构。这些针尖非常适合扫描探针显微镜（SPM）使用，因为它们预先确定了 SPM 的分辨率和用于光谱学的电子结构。提出了一种方案，以防止在从 FIM 转移到 SPM 的过程中由于气体杂质而导致针尖尖端的原子结构发生蚀刻，并就由于超高真空残余气体的污染而对这种实验的时间限制进行了估计。在避免任何电流设定点过冲以保持针尖完整性的同时，我们展示了从原子定义的钨针尖到金（111）、高定向热解石墨（HOPG）和硅（111）表面的隧道区域的接近方法的结果，在室温下。我们从这些实验中得出结论，在室温下进行隧道实验时，为了保持针尖完整性，表面的吸附原子迁移率和物理吸附气体限制了表面的选择。只有在隧穿到高反应性的硅（111）表面后，FIM 针尖尖端的原子结构才保持不变。
