Dagdeviren Omur E, Miyahara Yoichi, Mascaro Aaron, Grütter Peter
Department of Physics, McGill University, Montréal, Québec H3A 2T8, Canada.
Rev Sci Instrum. 2019 Jan;90(1):013703. doi: 10.1063/1.5061831.
Atomic force microscopy (AFM) is an analytical surface characterization tool which can reveal a sample's topography with high spatial resolution while simultaneously probing tip-sample interactions. Local measurement of chemical properties with high-resolution has gained much popularity in recent years with advances in dynamic AFM methodologies. A calibration factor is required to convert the electrical readout to a mechanical oscillation amplitude in order to extract quantitative information about the surface. We propose a new calibration technique for the oscillation amplitude of electrically driven probes using the principle of energy balance. Our technique relies on the measurement of the energy input to maintain the oscillation amplitude constant. With the measurement of the energy input to the probe, a mechanical oscillation amplitude is calculated and a calibration factor to convert the electrical readout in volts to a mechanical oscillation amplitude in Ångströms is obtained. We demonstrate the application of the new technique with a quartz tuning fork including the qPlus configuration, while the same principle can be applied to other piezoelectric resonators such as length extension resonators or piezoelectric cantilevers. The calibration factor obtained by this technique is found to be in agreement with using the thermal noise spectrum method for capsulated and decapsulated tuning forks and tuning forks in the qPlus configuration.
原子力显微镜（AFM）是一种分析表面表征工具，它能够以高空间分辨率揭示样品的形貌，同时探测针尖与样品之间的相互作用。近年来，随着动态原子力显微镜方法的进展，高分辨率化学性质的局部测量变得非常流行。为了提取有关表面的定量信息，需要一个校准因子将电读数转换为机械振荡幅度。我们提出了一种利用能量平衡原理对电驱动探针振荡幅度进行校准的新技术。我们的技术依赖于对维持振荡幅度恒定所需的能量输入进行测量。通过测量输入到探针的能量，计算出机械振荡幅度，并获得将以伏特为单位的电读数转换为以埃为单位的机械振荡幅度的校准因子。我们展示了这种新技术在包括qPlus配置的石英音叉上的应用，而相同的原理也可应用于其他压电谐振器，如长度延伸谐振器或压电悬臂梁。通过该技术获得的校准因子与使用热噪声谱方法对封装和解封装的音叉以及qPlus配置的音叉所得到的结果一致。
