Kirpal Dominik, Qiu Jinglan, Pürckhauer Korbinian, Weymouth Alfred J, Metz Michael, Giessibl Franz J
Institute of Experimental and Applied Physics, University of Regensburg, D-93053 Regensburg, Germany.
Rev Sci Instrum. 2021 Apr 1;92(4):043703. doi: 10.1063/5.0041369.
Frequency-modulation atomic force microscopy (AFM) with a qPlus sensor allows one to atomically resolve surfaces in a variety of environments ranging from low-temperature in ultra-high vacuum to ambient and liquid conditions. Typically, the tip is driven to oscillate vertically, giving a measure of the vertical force component. However, for many systems, the lateral force component provides valuable information about the sample. Measuring lateral and vertical force components simultaneously by oscillating vertically and laterally has so far only been demonstrated with relatively soft silicon cantilevers and optical detection. Here, we show that the qPlus sensor can be used in a biaxial mode with electrical detection by making use of the first flexural mode and the length extensional mode. We describe the necessary electrode configuration as well as the electrical detection circuit and compare the length extensional mode to the needle sensor. Finally, we show atomic resolution in ambient conditions of a mica surface and in ultra-high vacuum of a silicon surface. In addition to this, we show how any qPlus AFM setup can be modified to work as a biaxial sensor, allowing two independent force components to be recorded.
采用qPlus传感器的调频原子力显微镜（AFM）能够在从超高真空低温到环境及液体条件等多种环境下对表面进行原子级分辨。通常，针尖被驱动垂直振荡，以测量垂直力分量。然而，对于许多系统而言，横向力分量能提供有关样品的有价值信息。到目前为止，通过垂直和横向振荡同时测量横向和垂直力分量仅在相对较软的硅悬臂梁和光学检测中得到证实。在此，我们表明通过利用第一弯曲模式和长度拉伸模式，qPlus传感器可用于双轴模式并进行电学检测。我们描述了必要的电极配置以及电学检测电路，并将长度拉伸模式与针状传感器进行比较。最后，我们展示了在环境条件下云母表面以及在超高真空下硅表面的原子分辨率。除此之外，我们还展示了如何对任何qPlus AFM装置进行修改以用作双轴传感器，从而能够记录两个独立的力分量。
