Atomic Force Microscopy (AFM) is no longer used as a nanotechnology tool responsible for topography imaging. However, it is widely used in different fields to measure various types of material properties, such as mechanical, electrical, magnetic, or chemical properties. One of the recently developed characterization techniques is known as loss tangent. In loss tangent AFM, the AFM cantilever is excited, similar to amplitude modulation AFM (also known as tapping mode); however, the observable aspects are used to extract dissipative and conservative energies per cycle of oscillation. The ratio of dissipation to stored energy is defined as $\tan \delta$. This value can provide useful information about the sample under study, such as how viscoelastic or elastic the material is. One of the main advantages of the technique is the fact that it can be carried out by any AFM equipped with basic dynamic AFM characterization. However, this technique lacks some important experimental guidelines. Although there have been many studies in the past years on the effect of oscillation amplitude, tip radius, or environmental factors during the loss tangent measurements, there is still a need to investigate the effect of excitation frequency during measurements. In this paper, we studied four different sets of samples, performing loss tangent measurements with both first and second eigenmode frequencies. It is found that performing these measurements with higher eigenmode is advantageous, minimizing the tip penetration through the surface and therefore minimizing the error in loss tangent measurements due to humidity or artificial dissipations that are not dependent on the actual sample surface.

中文翻译：

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本征模频率对损耗角正切原子力显微镜测量的影响

原子力显微镜 (AFM) 不再用作负责地形成像的纳米技术工具。然而，它被广泛应用于不同领域以测量各种类型的材料特性，例如机械、电、磁或化学特性。最近开发的表征技术之一被称为损耗角正切。在损耗角正切AFM中，AFM悬臂被激发，类似于调幅AFM（也称为敲击模式）；然而，可观察的方面用于提取每个振荡周期的耗散和保守能量。耗散与储存能量之比定义为$\mathrm{棕褐色}\delta$. 该值可以提供有关所研究样品的有用信息，例如材料的粘弹性或弹性。该技术的主要优点之一是它可以由配备基本动态 AFM 表征的任何 AFM 执行。然而，这种技术缺乏一些重要的实验指南。尽管在过去的几年里已经有很多关于损耗角正切测量过程中振荡幅度、尖端半径或环境因素的影响的研究，但仍然需要研究测量过程中激励频率的影响。在本文中，我们研究了四组不同的样本，使用第一和第二本征模式频率执行损耗角正切测量。发现以更高的本征模式执行这些测量是有利的，