Low temperature ultrahigh vacuum scanning tunneling/ atomic force microscope with tuning fork sensor

在LOEWE Schwerpunkt“PriOSS - on - surface synthesis Principles”的框架下，有机分子在表面上的反应将被研究。这些研究的一项基本技术是用原子力显微镜对分子进行成像，在一定条件下，可以看到分子间和分子内的单个化学键。扫描原子力显微镜与音叉传感器是合适的，在超高真空5 K下工作。这种极好的分辨率的关键是用一氧化碳分子的探测尖端功能化，一氧化碳分子通常在高分辨率扫描之前从表面拾取。尖端功能化过程和分子的高分辨率成像都只能在样品温度5 K左右的低温下工作。此外，扫描过程必须由一个非常灵活的、可编程的电子系统控制，以便能够可视化三维结构，也称为三维光谱学。PriOSS项目框架中的另一个重要特征是同时激发传感器光束的不同谐波振荡。这些多频方法允许（几乎）独立但同时记录不同的力信号，从而实现新的扫描程序，并对分子力相互作用有更深入的了解。为了能够对分子进行长时间的测量，非常重要的是温度和漂移稳定性。控制电子设备必须是可编程的，并允许复杂的3D光谱测量。

In the frame of the LOEWE Schwerpunkt „PriOSS – Principles of On-Surface Synbthesis“ the reactions of organic molecules on surface will be investigated. An essential technique for these investigations is imaging the molecules with an atomic force microscope, which, under certain conditions, allows the visualization of individual chemical bonds, inter- as well as intra-molecular. For this a scanning atomic force microscope with tuning fork sensor is suitable, working at 5 K in ultrahigh vacuum. The key for this extremely good resolution is functionalization of the probing tip with a carbon monoxide molecule, which is usually picked-up with the tip from the surface before the high resolution scan. Both, the process of the tip functionalization as well as the high resolution imaging of the molecules only work at sample temperatures at low cryogenic temperatures around 5 K. Furthermore, the scan process must be controlled by a very flexible, programmable electronic system, in order to be able to visualize 3-dimensional structures, also called 3D spectroscopy. A further important feature in the frame of the PriOSS projects is the simultaneous excitation of different harmonic oscillation of the sensor beam. These multi-frequency methods allow the (almost) independent but simultaneous recording of different force signals, which enables novel scanning procedures and gives deeper insight into the molecular force interactions. Very important are temperature and drift stability, in order to be able to perform long time scale measurements on molecules. The control electronics must be programmable, and allow for complex 3D spectroscopy measurements.