Nanomechanical mapping in air or vacuum using multi-harmonic signals in tapping mode atomic force microscopy
Nanomechanical mapping in air or vacuum using multi-harmonic signals in tapping mode atomic force microscopy
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DOI：
10.1088/1361-6528/ab9390
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发表时间：
2020-11-06
期刊：
影响因子：
3.5
通讯作者：
Raman, Arvind
中科院分区：
文献类型：
--
作者：
Huda Shaik, Nurul;Reifenberger, Ronald G.;Raman, Arvind
我们提出了一种方法，通过该方法，在正常的轻敲模式（调幅）AFM扫描的样品在空气中或真空中与标准的microbellevers获得的多谐波信号可以用来定量映射的局部机械性能的样品，如弹性模量，粘附力，和压痕。该方法是基于观察，在轻敲模式操作在空气或真空中，0次和2次谐波信号的微悬臂梁振动遇到在大多数操作条件下，可以映射到足够的信噪比。通过测量驱动谐波的振幅和相位以及0次和2次谐波观测量，我们发现解析/半解析公式，这些多谐波观测量与几个经典的尖端-样品相互作用模型的局部力学性质。局部机械性能的最小二乘估计逐像素执行。该方法是通过计算以及实验数据上获得的聚苯乙烯和聚烯烃弹性体的聚合物共混物进行验证。
We present a method by which multi-harmonic signals acquired during a normal tapping mode (amplitude modulated) AFM scan of a sample in air or vacuum with standard microcantilevers can be used to map quantitatively the local mechanical properties of the sample such as elastic modulus, adhesion, and indentation. The approach is based on the observation that during the tapping mode operation in air or vacuum, the 0th and 2nd harmonic signals of microcantilever vibration are encountered under most operating conditions and can be mapped with sufficient signal to noise ratio. By measuring the amplitude and phase of the driven harmonic as well as the 0th and 2nd harmonic observables, we find analytical/semi-analytical formulas that relate these multi-harmonic observables to local mechanical properties for several classical tip-sample interaction models. Least squares estimation of the local mechanical properties is performed pixel by pixel. The method is validated through computations as well as experimental data acquired on a polymer blend made of Polystyrene and Polyolefin elastomer.