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Full-Text Articles in Nanoscience and Nanotechnology
Origins Of Phase Contrast In The Atomic Force Microscope In Liquids, John Melcher, Carolina Carrasco, Xin Xu, Jose L. Carrascosa, Julio Gomez-Herrero, Pedro Jose De Pablo, Arvind Raman
Origins Of Phase Contrast In The Atomic Force Microscope In Liquids, John Melcher, Carolina Carrasco, Xin Xu, Jose L. Carrascosa, Julio Gomez-Herrero, Pedro Jose De Pablo, Arvind Raman
Xin Xu
We study the physical origins of phase contrast in dynamic atomic force microscopy (dAFM) in liquids where low-stiffness microcantilever probes are often used for nanoscale imaging of soft biological samples with gentle forces. Under these conditions, we show that the phase contrast derives primarily from a unique energy flow channel that opens up in liquids due to the momentary excitation of higher eigenmodes. Contrary to the common assumption, phase-contrast images in liquids using soft microcantilevers are often maps of short-range conservative interactions, such as local elastic response, rather than tip-sample dissipation. The theory is used to demonstrate variations in local …
Compositional Contrast Of Biological Materials In Liquids Using The Momentary Excitation Of Higher Eigenmodes In Dynamic Atomic Force Microscopy, Xin Xu, John Melcher, Sudipta Basak, R. Reifenberger, Arvind Raman
Compositional Contrast Of Biological Materials In Liquids Using The Momentary Excitation Of Higher Eigenmodes In Dynamic Atomic Force Microscopy, Xin Xu, John Melcher, Sudipta Basak, R. Reifenberger, Arvind Raman
Xin Xu
Atomic Force microscope (AFM) cantilevers commonly used for imaging soft biological samples in liquids experience a momentary excitation of the higher eigenmodes at each tap. This transient response is very sensitive to the local sample elasticity under gentle imaging conditions because the higher eigenmode time period is comparable to the tip-sample contact time. By mapping the momentary excitation response, we demonstrate a new scanning probe spectroscopy capable of resolving with high sensitivity the variations in the elasticity of soft biological materials in liquids.
Dynamics Of Surface-Coupled Microcantilevers In Force Modulation Atomic Force Microscopy - Magnetic Vs. Dither Piezo Excitation, Xin Xu, Marisol Koslowski, Arvind Raman
Dynamics Of Surface-Coupled Microcantilevers In Force Modulation Atomic Force Microscopy - Magnetic Vs. Dither Piezo Excitation, Xin Xu, Marisol Koslowski, Arvind Raman
Xin Xu
Force modulation atomic force microscopy is widely used for mapping the nanoscale mechanical properties of heterogeneous or composite materials using low frequency excitation of a microcantilever scanning the surface. Here we show that the excitation mode - magnetic or dither piezo, has a major influence on the surface-coupled microcantilever dynamics. Not only is the observed material property contrast inverted between these excitation modes but also the frequency response of the surface-coupled cantilever in the magnetic mode is near-ideal with a clear resonance peak and little phase distortion thus enabling quantitative mapping of the local mechanical properties. (C) 2012 American Institute …
Accurate Force Spectroscopy In Tapping Mode Atomic Force Microscopy In Liquids, Xin Xu, John Melcher, Arvind Raman
Accurate Force Spectroscopy In Tapping Mode Atomic Force Microscopy In Liquids, Xin Xu, John Melcher, Arvind Raman
Xin Xu
Existing force spectroscopy methods in tapping mode atomic force microscopy (AFM) such as higher harmonic inversion [M. Stark, R. W. Stark, W. M. Heckl, and R. Guckenberger, Proc. Natl. Acad. Sci. U. S. A. 99, 8473 (2002)] or scanning probe acceleration microscopy [J. Legleiter, M. Park, B. Cusick, and T. Kowalewski, Proc. Natl. Acad. Sci. U. S. A. 103, 4813 (2006)] or integral relations [M. Lee and W. Jhe, Phys. Rev. Lett. 97, 036104 (2006); S. Hu and A. Raman, Nanotechnology 19, 375704 (2008); H. Holscher, Appl. Phys. Lett. 89, 123109 (2006); A. J. Katan, Nanotechnology 20, 165703 (2009)] require …