Rahe Philipp, Heile Daniel, Olbrich Reinhard, Reichling Michael
Fachbereich Physik, Universität Osnabrück, Barbarastrasse 7, 49076 Osnabrück, Germany.
Beilstein J Nanotechnol. 2022 Jul 6;13:610-619. doi: 10.3762/bjnano.13.53. eCollection 2022.
In the mathematical description of dynamic atomic force microscopy (AFM), the relation between the tip-surface normal interaction force, the measurement observables, and the probe excitation parameters is defined by an average of the normal force along the sampling path over the oscillation cycle. Usually, it is tacitly assumed that tip oscillation and force data recording follows the same path perpendicular to the surface. Experimentally, however, the sampling path representing the tip oscillating trajectory is often inclined with respect to the surface normal and the data recording path. Here, we extend the mathematical description of dynamic AFM to include the case of an inclined sampling path. We find that the inclination of the tip movement can have critical consequences for data interpretation, especially for measurements on nanostructured surfaces exhibiting significant lateral force components. Inclination effects are illustrated by simulation results that resemble the representative experimental conditions of measuring a heterogeneous atomic surface. We propose to measure the AFM observables along a path parallel to the oscillation direction in order to reliably recover the force along this direction.
在动态原子力显微镜（AFM）的数学描述中，针尖 - 表面法向相互作用力、测量可观测量与探针激发参数之间的关系是通过沿振荡周期内采样路径的法向力平均值来定义的。通常，人们默认针尖振荡和力数据记录沿着垂直于表面的同一路径进行。然而，在实验中，代表针尖振荡轨迹的采样路径往往相对于表面法线和数据记录路径是倾斜的。在此，我们扩展了动态AFM的数学描述，以纳入倾斜采样路径的情况。我们发现，针尖运动的倾斜度可能对数据解释产生关键影响，特别是对于在具有显著横向力分量的纳米结构表面上进行的测量。通过类似于测量异质原子表面代表性实验条件的模拟结果说明了倾斜效应。我们建议沿着与振荡方向平行的路径测量AFM可观测量，以便可靠地恢复沿该方向的力。
