Visualizing the Subsurface of Soft Matter: Simultaneous Topographical Imaging, Depth Modulation, and Compositional Mapping with Triple Frequency Atomic Force Microscopy
Visualizing the Subsurface of Soft Matter: Simultaneous Topographical Imaging, Depth Modulation, and Compositional Mapping with Triple Frequency Atomic Force Microscopy
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DOI：
10.1021/nn404845q
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发表时间：
2013-11-01
期刊：
影响因子：
17.1
通讯作者：
Solares, Santiago De Jesus
中科院分区：
文献类型：
--
作者：
Ebeling, Daniel;Eslami, Babak;Solares, Santiago De Jesus
具有纳米级分辨率和深度控制的表面下形态和机械性能的表征在软物质领域如生物学、聚合物科学甚至在未来的应用如纳米制造中具有重要意义，其中埋藏的结构和成分特征对系统的功能性很重要。然而，可控地“感觉”地下是一项具有挑战性的任务，可用的成像工具相对有限。在本文中，我们提出了一个三模态原子力显微镜（AFM）成像方案，从而三个本征模式的微悬臂梁探针被用作单独的控制“旋钮”，同时测量的地形，调制样品压痕的尖端在尖端样品的影响，和地图的成分对比度，分别。我们说明了这种多频成像方法，通过计算模拟和实验进行嵌入式玻璃纳米粒子在环境空气中的聚合物薄膜。通过使用悬臂梁的更高本征模主动增加尖端样品压痕，我们能够逐渐且可控地揭示埋在表面下数十纳米深的玻璃纳米颗粒，同时仍然能够重新聚焦在表面上。
Characterization of subsurface morphology and mechanical properties with nanoscale resolution and depth control is of significant interest in soft matter fields like biology, polymer science, and even in future applications like nanomanufacturing, where buried structural and compositional features are important to the functionality of the system. However, controllably "feeling" the subsurface is a challenging task for which the available imaging tools are relatively limited. In this paper, we propose a trimodal atomic force microscopy (AFM) imaging scheme, whereby three eigenmodes of the microcantilever probe are used as separate control "knobs" to simultaneously measure the topography, modulate sample indentation by the tip during tip-sample impact, and map compositional contrast, respectively. We illustrate this multifrequency imaging approach through computational simulation and experiments conducted on ultrathin polymer films with embedded glass nanoparticles in ambient air. By actively increasing the tip-sample indentation using a higher eigenmode of the cantilever, we are able to gradually and controllably reveal glass nanoparticles which are buried tens of nanometers deep under the surface, while still being able to refocus on the surface.