CNR-Istituto di Struttura della Materia, via del Fosso del Cavaliere 100, I-00133 Roma, Italy.
J Phys Condens Matter. 2010 Jul 7;22(26):264003. doi: 10.1088/0953-8984/22/26/264003. Epub 2010 Jun 14.
After almost three decades since the invention of the scanning tunnelling microscope (STM) its application to the study of dynamic processes at surfaces is attracting a great deal of interest due to its unique capacity to observe such processes at the atomic level. The α-phase of group IV adatoms on Ge(111) and Si(111) is the ideal playground for the analysis of critical phenomena and represents a prototype of a two-dimensional electron system exhibiting thermally activated peculiar Sn adatom dynamics. This paper will relate the study of adatom dynamics at the α-Sn/Ge(111) and α-Sn/Si(111) surfaces, discussing in detail the methods we used for such kinds of time-resolved measurements. The microscope tip was used to record the tunnelling current on top of an oscillating Sn adatom, keeping the feedback loop turned off. The dynamics of the adatoms is detected as telegraph noise present in the tunnelling versus time curves. With this method it is possible to increase the acquisition rate to the actual limit of the instrument electronics, excluding piezo movement and feedback circuitry response time. We put emphasis on the statistical data analysis which allows the localization of the sample areas that are involved in dynamical processes.
自扫描隧道显微镜（STM）发明以来，将近三十年过去了，由于其独特的能力，可以在原子水平上观察到这些过程，因此其在表面动态过程研究方面的应用引起了极大的兴趣。Ge(111) 和 Si(111) 上 IV 族原子的 α 相是分析临界现象的理想场所，它代表了一个二维电子系统的原型，表现出热激活的独特 Sn 原子动力学。本文将介绍在α-Sn/Ge(111) 和 α-Sn/Si(111) 表面上研究原子动力学的情况，详细讨论了我们用于这种时间分辨测量的方法。使用显微镜针尖在振荡的 Sn 原子上记录隧穿电流，同时关闭反馈回路。通过隧穿电流与时间曲线中的电报噪声来检测原子的动力学。通过这种方法，可以将采集率提高到仪器电子学的实际极限，而不考虑压电运动和反馈电路的响应时间。我们重点介绍了统计数据分析，该方法允许对涉及动态过程的样品区域进行定位。
