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- Keyword
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- Atomic force microscopy (1)
- Atomic force microscopy; liquid environments; energy dissipation; higher eigenmodes; momentary excitation (1)
- ELASTIC-MODULUS; MICROCRYSTALLINE CELLULOSE; POLYMER NANOCOMPOSITES; NATIVE CELLULOSE; CRYSTALLINE REGIONS; BACTERIAL CELLULOSE; CANTILEVER DYNAMICS; I-ALPHA; WHISKERS; FIBERS (1)
- Force spectroscopy (1)
- NANOSCALE PROPERTY VARIATIONS; MECHANICAL-PROPERTIES; CANTILEVERS; INTERPHASE; LIQUID (1)
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Articles 1 - 6 of 6
Full-Text Articles in Nanoscience and Nanotechnology
Multiscale Contact Mechanics Model For Rf-Mems Switches With Quantified Uncertainties, Hojin Kim, Nurul Shaik, Xin Xu, Arvind Raman, Alejandro Strachan
Multiscale Contact Mechanics Model For Rf-Mems Switches With Quantified Uncertainties, Hojin Kim, Nurul Shaik, Xin Xu, Arvind Raman, Alejandro Strachan
Xin Xu
We introduce a multiscale model for contact mechanics between rough surfaces and apply it to characterize the force-displacement relationship for a metal-dielectric contact relevant for radio frequency micro-electromechanicl system (MEMS) switches. We propose a mesoscale model to describe the history-dependent force-displacement relationships in terms of the surface roughness, the long-range attractive interaction between the two surfaces, and the repulsive interaction between contacting asperities (including elastic and plastic deformation). The inputs to this model are the experimentally determined surface topography and the Hamaker constant as well as the mechanical response of individual asperities obtained from density functional theory calculations and large-scale …
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 …
Atomic Force Microscopy Characterization Of Cellulose Nanocrystals, Roya Lahiji, Xin Xu, R. Reifenberger, Arvind Raman, Alan Rudie, Robert Moon
Atomic Force Microscopy Characterization Of Cellulose Nanocrystals, Roya Lahiji, Xin Xu, R. Reifenberger, Arvind Raman, Alan Rudie, Robert Moon
Xin Xu
Cellulose nanocrystals (CNCs) are gaining interest as a "green" nanomaterial with superior mechanical and chemical properties for high-performance nanocomposite materials; however, there is a lack of accurate material property characterization of individual CNCs. Here, a detailed Study of the topography, elastic and adhesive properties of individual wood-derived CNCs is performed using atomic force microscopy (AFM). AFM experiments involving high-resolution dynamic mode imaging and jump-mode measurements were performed on individual CNCs under ambient conditions with 30% relative humidity (RH) and under a N-2 atmosphere with 0.1% RH. A procedure was also developed to calculate the CNC transverse elastic modulus (E-T) by …
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 …