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Microscopic Analysis of Current and Mechanical Properties of Nafion? Studied by Atomic Force Microscopy  [PDF]
Renate Hiesgen,Stefan Helmly,Ines Galm,Tobias Morawietz,Michael Handl,K. Andreas Friedrich
Membranes , 2012, DOI: 10.3390/membranes2040783
Abstract: The conductivity of fuel cell membranes as well as their mechanical properties at the nanometer scale were characterized using advanced tapping mode atomic force microscopy (AFM) techniques. AFM produces high-resolution images under continuous current flow of the conductive structure at the membrane surface and provides some insight into the bulk conducting network in Nafion membranes. The correlation of conductivity with other mechanical properties, such as adhesion force, deformation and stiffness, were simultaneously measured with the current and provided an indication of subsurface phase separations and phase distribution at the surface of the membrane. The distribution of conductive pores at the surface was identified by the formation of water droplets. A comparison of nanostructure models with high-resolution current images is discussed in detail.
Atomic force microscopy in cell biology
Zhexue Lu,Zhiling Zhang,Daiwen Pang
Chinese Science Bulletin , 2005, DOI: 10.1360/982004-843
Abstract: The history, characteristic, operation modes and coupling techniques of atomic force microscopy (AFM) are introduced. Then the application in cell biology is reviewed in four aspects: cell immobilization methods, cell imaging, force spectrum study and cell manipulation. And the prospect of AFM application in cell biology is discussed.
Advances in atomic force microscopy  [PDF]
Franz J. Giessibl
Physics , 2003, DOI: 10.1103/RevModPhys.75.949
Abstract: This article reviews the progress of atomic force microscopy (AFM) in ultra-high vacuum, starting with its invention and covering most of the recent developments. Today, dynamic force microscopy allows to image surfaces of conductors \emph{and} insulators in vacuum with atomic resolution. The mostly used technique for atomic resolution AFM in vacuum is frequency modulation AFM (FM-AFM). This technique, as well as other dynamic AFM methods, are explained in detail in this article. In the last few years many groups have expanded the empirical knowledge and deepened the theoretical understanding of FM-AFM. Consequently, the spatial resolution and ease of use have been increased dramatically. Vacuum AFM opens up new classes of experiments, ranging from imaging of insulators with true atomic resolution to the measurement of forces between individual atoms.
A learning-control system for advanced atomic-force-microscopy scanning mode

FANG Yong-chun,ZHANG Yu-dong,JIA Ning,

控制理论与应用 , 2010,
Abstract: Atomic-force-microscopy(AFM) is an important instrument for nanoscale measurement and manipulation. This paper proposes a learning-control advanced scanning mode for an AFM system. Specifically, a learning-control scheme is designed for the AFM system, which consists of an optimal inverse compensator for the AFM scanner dynamics and a learning algorithm dealing with the surface profile of the detected sample. Based on the observation of the offset among neighboring scanning lines, the aforementioned learning-control scheme combined with a conventional proportional-integral(PI) controller realizes the advanced AFM scanning mode. The designed scanning mode is then utilized for periodic samples to test its performance. As demonstrated by simulation and experimental results, this scanning mode can greatly increase the measurement speed and precision, and simultaneously keep the distance between the cantilever tip and the detected sample within a reasonable range to avoid possible harm to them. Therefore, the proposed advanced scanning mode can be employed for online inspection of fast biologic processes, and it can also be utilized to implement such nanomanipulation as repetitive writing.
Application of dynamic impedance spectroscopy to atomic force microscopy
Kazimierz Darowicki, Artur Zieliński and Krzysztof J Kurzyd?owski
Science and Technology of Advanced Materials , 2008,
Abstract: Atomic force microscopy (AFM) is a universal imaging technique, while impedance spectroscopy is a fundamental method of determining the electrical properties of materials. It is useful to combine those techniques to obtain the spatial distribution of an impedance vector. This paper proposes a new combining approach utilizing multifrequency scanning and simultaneous AFM scanning of an investigated surface.
Uncertainty of atomic force microscopy measurements  [PDF]
Teodor P. Gotszalk,Pawel Janus,Andrzej Marendziak,Roman F. Szeloch
Optica Applicata , 2007,
Abstract: We consider the problem of uncertainty in geometrically linear measurements in scanning probe microscopy (SPM) represented by atomic force microscopy (AFM). The uncertainties under consideration are associated both with quantum phenomena in the space cantilever tip–sample surfaces and with effects of dynamic behavior of electronic and optic measurement and control systems. In our experiment, we have analyzed uncertainty of calibrated atomic force microscopy (C-AFM) measurement in two dimensions. Uncertainty of measurements has been estimated according to GUM procedure.
Prior Surface Integrity Assessment of Coated and Uncoated Carbide Inserts Using Atomic Force Microscopy  [PDF]
Samy Oraby,Ayman Alaskari,Abdulla Almazrouee
Materials , 2011, DOI: 10.3390/ma4040633
Abstract: Coated carbide inserts are considered vital components in machining processes and advanced functional surface integrity of inserts and their coating are decisive factors for tool life. Atomic Force Microscopy (AFM) implementation has gained acceptance over a wide spectrum of research and science applications. When used in a proper systematic manner, the AFM features can be a valuable tool for assessment of tool surface integrity. The aim of this paper is to assess the integrity of coated and uncoated carbide inserts using AFM analytical parameters. Surface morphology of as-received coated and uncoated carbide inserts is examined, analyzed, and characterized through the determination of the appropriate scanning setting, the suitable data type imaging techniques and the most representative data analysis parameters using the MultiMode AFM microscope in contact mode. The results indicate that it is preferable to start with a wider scan size in order to get more accurate interpretation of surface topography. Results are found credible to support the idea that AFM can be used efficiently in detecting flaws and defects of coated and uncoated carbide inserts using specific features such as “Roughness” and “Section” parameters. A recommended strategy is provided for surface examination procedures of cutting inserts using various AFM controlling parameters.
Polynomial force approximations and multifrequency atomic force microscopy  [PDF]
Daniel Platz,Daniel Forchheimer,Erik A. Tholen,David B. Haviland
Physics , 2013,
Abstract: We present polynomial force reconstruction from experimental intermodulation atomic force microscopy (ImAFM) data. We study the tip-surface force during a slow surface approach and compare the results with amplitude-dependence force spectroscopy. Based on polynomial force reconstruction we generate high-resolution surface property maps of polymer blend samples. The polynomial method is described as a special example of a more general approximataive force reconstruction, where the aim is to determine model parameters which best approximate the measured force spectrum. This approximative approach is not limited to spectral data and we demonstrate how is can adapted to a force quadrature picture.
Nanoscale Structure and Energy Dissipation Behaviour of Tungsten Disulphide and Gold Nanoparticles and Nanoclusters Investigated by Advanced Microscopy Techniques  [PDF]
D. Devaprakasam
Physics , 2013,
Abstract: In this study nanoscale structure and associated energy dissipation behavior of nanoparticulates of tungsten disulphide (WS2) and nanoparticles of gold (Au) were investigated by advanced scanning probe and electron microscopy techniques. WS2 nanoparticulates were deposited on silicon substrate by van der Waals adhesion transfer-deposition mechanisms. The templates of three size variants of Au nanoparticles, close packed (4-6nm), well dispersed (120-150nm) and clusters of (120-150 nm) nanoparticles were prepared on silicon substrates. Nano-microstructure, morphology, topography and phase shift of both WS2 and Au nanoparticles and nanoparticulates were characterized by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). SEM and TEM observations showed that the nanoparticulates of WS2 are atomically oriented lamellar-hexagonal structure or inorganic graphite like structure. In the tapping mode AFM imaging, repeated scanning of nanoparticulates of WS2 resulted in inter layer movement of nanolayers. It was observed that cluster of Au nanoparticles caused more phase shift and high energy dissipation compared to that of well dispersed Au nanoparticles, however close packed Au nanoparticles caused lowest phase shift and energy dissipation. Nano-microstructure, morphology, topography and phase shift were analyzed by SXM software. The nanoscale studies showed that the phase shift and the energy dissipation were influenced by the geometrical and mechanical gradient of the samples.
Anharmonicity in multifrequency atomic force microscopy  [PDF]
Sergio Santos,Victor Barcons
Physics , 2014,
Abstract: In multifrequency atomic force microscopy higher eigenmodes are externally excited to enhance resolution and contrast while simultaneously increasing the number of experimental observables with the use of gentle forces. Here, the implications of externally exciting multiple frequencies are discussed in terms of cantilever anharmonicity, fundamental period and the onset of subharmonic and superharmonic components. Cantilever anharmonicity is shown to affect and control both the observables, that is, the monitored amplitudes and phases, and the main expressions quantified via these observables, that is, the virial and energy transfer expressions which form the basis of the theory.
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