The Experts below are selected from a list of 13896 Experts worldwide ranked by ideXlab platform
Angela M. Belcher - One of the best experts on this subject based on the ideXlab platform.
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label free and high resolution protein dna nanoarray analysis using Kelvin Probe force microscopy
Nature Nanotechnology, 2007Co-Authors: Asher K. Sinensky, Angela M. BelcherAbstract:Using the scanning Probe technique known as Kelvin Probe force microscopy it is possible to successfully devise a sensor for charged biomolecules. The Kelvin Probe force microscope is a tool for measuring local variations in surface potential across a substrate of interest. Because many biological molecules have a native state that includes the presence of charge centres (such as the negatively charged backbone of DNA), the formation of highly specific complexes between biomolecules will often be accompanied by local changes in charge density. By spatially resolving this variation in surface potential it is possible to measure the presence of a specific bound target biomolecule on a surface without the aid of special chemistries or any form of labelling. The Kelvin Probe force microscope presented here is based on an atomic force microscopy nanoProbe offering high resolution ( 1,100 microm s(-1)), and the ability to resolve as few as three nucleotide mismatches.
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Label-free and high-resolution protein/DNA nanoarray analysis using Kelvin Probe force microscopy.
Nature Nanotechnology, 2007Co-Authors: Asher K. Sinensky, Angela M. BelcherAbstract:Using the scanning Probe technique known as Kelvin Probe force microscopy it is possible to successfully devise a sensor for charged biomolecules. The Kelvin Probe force microscope is a tool for measuring local variations in surface potential across a substrate of interest. Because many biological molecules have a native state that includes the presence of charge centres (such as the negatively charged backbone of DNA), the formation of highly specific complexes between biomolecules will often be accompanied by local changes in charge density. By spatially resolving this variation in surface potential it is possible to measure the presence of a specific bound target biomolecule on a surface without the aid of special chemistries or any form of labelling. The Kelvin Probe force microscope presented here is based on an atomic force microscopy nanoProbe offering high resolution ( 1,100 microm s(-1)), and the ability to resolve as few as three nucleotide mismatches.
Michael Rohwerder - One of the best experts on this subject based on the ideXlab platform.
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interfacial hydrogen localization in austenite martensite dual phase steel visualized through optimized silver decoration and scanning Kelvin Probe force microscopy
Materials and Corrosion-werkstoffe Und Korrosion, 2017Co-Authors: Tatsuya Nagashima, Asif Bashir, Motomichi Koyama, Eiji Akiyama, Dierk Raabe, Cemal Cem Tasan, Michael Rohwerder, Kaneaki TsuzakiAbstract:The hydrogen distribution in an austenite–martensite dual-phase steel was investigated using silver decoration and scanning Kelvin Probe force microscopy. The silver decoration technique optimized for spacial resolution reveals interfacial segregation of hydrogen along the plate-type martensite–martensite grain boundaries. In addition, the scanning Kelvin Probe force microscopy kinetically elucidates that hydrogen preferentially diffused out from the martensite–martensite grain boundaries. These preferential sites of hydrogen desorption correspond to the regions of hydrogen-assisted damage.
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Investigation of the Interaction between H2 and trap sites in Duplex Steel by Scanning Kelvin Probe Force Microscopy
2012Co-Authors: Stefan Evers, Ceylan Senöz, Michael RohwerderAbstract:Even very low concentrations of hydrogen can give rise to hydrogen embrittlement. However, suitable high resolution techniques which provide high sensitivity for hydrogen detection, if possible also with spatial information, are missing. Recently it was shown by us that scanning Probe microscopy techniques such as scanning Kelvin Probe (SKP) and scanning Kelvin Probe force microscopy (SKPFM) may find applications as well as in this field where they can both be utilized for the detection of very low levels of hydrogen with high lateral resolution [1].
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high resolution Kelvin Probe microscopy in corrosion science scanning Kelvin Probe force microscopy skpfm versus classical scanning Kelvin Probe skp
Electrochimica Acta, 2007Co-Authors: Michael Rohwerder, Florin TurcuAbstract:With the introduction of a Kelvin Probe mode to atomic force microscopy, the so called scanning Kelvin Probe force microscopy (SKPFM), the Kelvin Probe technique finds application in a steadily increasing number of different fields, from corrosion science to microelectronics and biosciences. For many of these applications, high resolution is required as the relevant information lies in the sub-microscopic distribution of work functions or potentials, which explains the increasing interest in SKPFM. However, compared to the standard scanning Kelvin Probe (SKP) technique SKPFM is prone to much more artefacts, which are often not taken into account in the interpretation of the results, as is also the case with the real physical nature of the measured data. A critical discussion of possible artefacts and on the interpretation of the data is presented in this paper, with the main focus on application in corrosion science.
Lukas M. Eng - One of the best experts on this subject based on the ideXlab platform.
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Tracking speed bumps in organic field-effect transistors via pump-Probe Kelvin-Probe force microscopy
Journal of Applied Physics, 2015Co-Authors: J. Murawski, Peter Milde, U. Zerweck-trogisch, Tobias Mönch, M. P. Hein, S. Nicht, Lukas M. EngAbstract:One of the great challenges in designing modern organic field-effect transistors is lowering the injection barriers that arise at the interfaces between the metallic electrodes and the semiconducting transport channel. Currently, these barriers are quantified mostly by time-independent and external inspection, techniques lacking temporal insight into the most relevant switching dynamics. We address this problem here by pump-Probe Kelvin-Probe force microscopy, which combines the high spatial resolution of standard Kelvin-Probe force microscopy with a pump-Probe, enabling time resolution down to nanoseconds. When investigating a dynamically operated pentacene-based organic field-effect transistor, pump-Probe Kelvin-Probe force microscopy is capable of in-situ probing the temporal charge evolution at any sample spot within the device. Thus, Schottky-barriers arising at the boundaries between electrodes and transport channel are identified as speed bumps for high-speed organic field-effect transistor operation, manifested by residual charges that are retained within the organic film upon switching the device.
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Pump-Probe Kelvin-Probe force microscopy: Principle of operation and resolution limits
Journal of Applied Physics, 2015Co-Authors: J. Murawski, T. Graupner, Peter Milde, R. Raupach, U. Zerweck-trogisch, Lukas M. EngAbstract:Knowledge on surface potential dynamics is crucial for understanding the performance of modern-type nanoscale devices. We describe an electrical pump-Probe approach in Kelvin-Probe force microscopy that enables a quantitative measurement of dynamic surface potentials at nanosecond-time and nanometer-length scales. Also, we investigate the performance of pump-Probe Kelvin-Probe force microscopy with respect to the relevant experimental parameters. We exemplify a measurement on an organic field effect transistor that verifies the undisturbed functionality of our pump-Probe approach in terms of simultaneous and quantitative mapping of topographic and electronic information at a high lateral and temporal resolution.
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Kelvin Probe force microscopy of C60 on metal substrates : towards molecular resolution
Nanotechnology, 2007Co-Authors: Ulrich Zerweck, Ch. Loppacher, Tobias Otto, Stefan Grafström, Lukas M. EngAbstract:Surface workfunction changes upon C60 adsorption onto different metal single crystals are investigated by Kelvin Probe force microscopy (KPFM). Literature values for similar metal/organic systems, showing a broad variation for both the measured metal workfunction and workfunction change, are compared to the acquired KPFM values. Good agreement is found between nanoscopic KPFM results and macroscopic photoelectron spectroscopy or Kelvin Probe literature data. The model of a linear dependence between the metal substrate workfunction and the C60-induced workfunction change is confirmed. Former numerical simulations predicted a lateral quantitative KPFM resolution in the range of 10 nm, in this work results are published that show the achievement of this resolution with Cr coated, sharp tips. Furthermore, numerical simulations are presented that show the possibility of molecular contrast for KPFM.
Geraint Williams - One of the best experts on this subject based on the ideXlab platform.
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Latent Fingerprint Visualization using a Scanning Kelvin Probe in Conjunction with Vacuum Metal Deposition
Journal of Forensic Sciences, 2013Co-Authors: Hefin Ap Llwyd Dafydd, Geraint Williams, Stephen M. BleayAbstract:The application of vacuum metal deposition before scanning Kelvin Probe visualization of fingerprints is investigated. The potential contrast between fingerprint ridges and furrows is maximized by the use of silver deposition for non-noble metals and gold-zinc deposition for noble metals. The higher susceptibility of eccrine fingerprints to vacuum metal overdeposition is confirmed. Additionally, fingerprints are best developed individually and by building the metal deposition slowly to protect against overdevelopment and variation in the rate of metal condensation. The progress of the metal deposition can be monitored using the scanning Kelvin Probe by reference to the change in potential and continuity of the new potential on the surface. The use of acetic acid solution for the recovery of overVMD-developed samples is shown not to be useful. Applying the metal deposition has the additional prospect of increasing surface conductivity and homogeneity and both can aid fingerprint visualization using the scanning Kelvin Probe.
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calibration of the scanning Kelvin Probe force microscope under controlled environmental conditions
Electrochimica Acta, 2012Co-Authors: Anthony Cook, Zak Barrett, S B Lyon, H N Mcmurray, J Walton, Geraint WilliamsAbstract:Abstract Local Volta potential differences (Δ ψ ) between a platinum coated AFM tip and various pure metal specimens with a thin humidity induced surface electrolyte layer have been determined via scanning Kelvin Probe force microscopy (SKPFM). SKPFM derived Δ ψ display a linear correlation with the same quantities obtained under nominally identical environmental conditions using a scanning Kelvin Probe (SKP); the slope is within experimental error one. By exploiting this correlation and using a SKP previously calibrated versus a series of metal/aqueous metal ion redox couples it is possible to indirectly calibrate atmospheric SKPFM derived Δ ψ with electrochemical potential. Good correlation is also obtained between immersion corrosion potential ( E corr ) in NaCl electrolyte and SKP determined Δ ψ in the presence of a NaCl dosed humidity layer. This implies that SKPFM may be calibrated directly against immersion E corr provided SKPFM measurements are performed under suitably controlled conditions of atmospheric relative humidity and surface electrolyte dosing.
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Latent fingermark visualisation using a scanning Kelvin Probe.
Forensic Science International, 2006Co-Authors: Geraint Williams, Neil McmurrayAbstract:The current state of the art in fingermark visualisation on metallic surfaces by a scanning Kelvin Probe (SKP) technique is described. Latent eccrine fingermarks deposited on a range of polished and roughened metallic surfaces can be effectively imaged. Results are presented which show that the SKP technique is able to visualise fingermarks obscured beneath optically opaque soot films and retrieve ridge detail in instances where fingermarks have been physically removed (e.g. by rubbing with a tissue) from a metal surface. SKP Volta potential mapping of small, severely non-planar metal objects such as fired brass cartridge cases is demonstrated.
Asher K. Sinensky - One of the best experts on this subject based on the ideXlab platform.
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label free and high resolution protein dna nanoarray analysis using Kelvin Probe force microscopy
Nature Nanotechnology, 2007Co-Authors: Asher K. Sinensky, Angela M. BelcherAbstract:Using the scanning Probe technique known as Kelvin Probe force microscopy it is possible to successfully devise a sensor for charged biomolecules. The Kelvin Probe force microscope is a tool for measuring local variations in surface potential across a substrate of interest. Because many biological molecules have a native state that includes the presence of charge centres (such as the negatively charged backbone of DNA), the formation of highly specific complexes between biomolecules will often be accompanied by local changes in charge density. By spatially resolving this variation in surface potential it is possible to measure the presence of a specific bound target biomolecule on a surface without the aid of special chemistries or any form of labelling. The Kelvin Probe force microscope presented here is based on an atomic force microscopy nanoProbe offering high resolution ( 1,100 microm s(-1)), and the ability to resolve as few as three nucleotide mismatches.
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Label-free and high-resolution protein/DNA nanoarray analysis using Kelvin Probe force microscopy.
Nature Nanotechnology, 2007Co-Authors: Asher K. Sinensky, Angela M. BelcherAbstract:Using the scanning Probe technique known as Kelvin Probe force microscopy it is possible to successfully devise a sensor for charged biomolecules. The Kelvin Probe force microscope is a tool for measuring local variations in surface potential across a substrate of interest. Because many biological molecules have a native state that includes the presence of charge centres (such as the negatively charged backbone of DNA), the formation of highly specific complexes between biomolecules will often be accompanied by local changes in charge density. By spatially resolving this variation in surface potential it is possible to measure the presence of a specific bound target biomolecule on a surface without the aid of special chemistries or any form of labelling. The Kelvin Probe force microscope presented here is based on an atomic force microscopy nanoProbe offering high resolution ( 1,100 microm s(-1)), and the ability to resolve as few as three nucleotide mismatches.
