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Auswahl der wissenschaftlichen Literatur zum Thema „Non-Contact mode Atomic Force Microscopy (nc-AFM)“
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Zeitschriftenartikel zum Thema "Non-Contact mode Atomic Force Microscopy (nc-AFM)"
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Hosaka, Sumio, Takayuki Takizawa, Daisuke Terauchi, You Yin und Hayato Sone. „Pico-Newton Controlled Step-in Mode NC-AFM Using a Quadrature Frequency Demodulator and a Slim Probe in Air for CD-AFM“. Key Engineering Materials 497 (Dezember 2011): 95–100. http://dx.doi.org/10.4028/www.scientific.net/kem.497.95.
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We have studied a step-in mode non-contact atomic force microscopy (NC-AFM) for precise measurement of fine and steep structure with nanometer resolution in air. When a high aspect structure is measured using step-in mode AFM with the sharpened and slim probe, it is required that AFM control has to be performed at a force of <1 nN in pico-Newton range to suppress the bending and slipping of the probe on slop. Using a home-made step-in mode NC-AFM using a quadrature frequency demodulator for resonant frequency shift of the cantilever, the NC-AFM demonstrated that Si steep structure was faithfully observed at about 2 pN in air.
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König, Thomas, Georg H. Simon, Lars Heinke, Leonid Lichtenstein und Markus Heyde. „Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy“. Beilstein Journal of Nanotechnology 2 (03.01.2011): 1–14. http://dx.doi.org/10.3762/bjnano.2.1.
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Surfaces of thin oxide films were investigated by means of a dual mode NC-AFM/STM. Apart from imaging the surface termination by NC-AFM with atomic resolution, point defects in magnesium oxide on Ag(001) and line defects in aluminum oxide on NiAl(110), respectively, were thoroughly studied. The contact potential was determined by Kelvin probe force microscopy (KPFM) and the electronic structure by scanning tunneling spectroscopy (STS). On magnesium oxide, different color centers, i.e., F0, F+, F2+ and divacancies, have different effects on the contact potential. These differences enabled classification and unambiguous differentiation by KPFM. True atomic resolution shows the topography at line defects in aluminum oxide. At these domain boundaries, STS and KPFM verify F2+-like centers, which have been predicted by density functional theory calculations. Thus, by determining the contact potential and the electronic structure with a spatial resolution in the nanometer range, NC-AFM and STM can be successfully applied on thin oxide films beyond imaging the topography of the surface atoms.
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Chernoff, Ellen A. G., Donald A. Chernoff und Kevin Kjoller. „Contact and non-contact atomic-force microscopy of type I collagen“. Proceedings, annual meeting, Electron Microscopy Society of America 51 (01.08.1993): 518–19. http://dx.doi.org/10.1017/s0424820100148423.
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Introduction. Type I collagen was examined using two types of atomic force microscopes (AFM) in a continuing effort to refine the process of obtaining molecular information from biological materials using scanning probe microscopy. Operating in air, a contact mode (Nanoscope II) and a non-contact mode AFM (Nanoscope III) were used to image collagen fibrils polymerized from pepsin-extracted type I bovine skin collagen adsorbed onto mica substrates. AFM is a practical method for high resolution examination of extracellular matrix material without the time consuming preparative techniques required for electron microscopy.Methods. For fibrillar collagen samples, Vitrogen 100 (Collagen Corporation, Palo Alto, CA) was prepared according to a modification of the procedure provided by Collagen Corp. for neutralized isotonic collagen gels. Monomeric collagen samples were prepared by diluting the vitrogen in 0.012M HCl.Images captured with the Nanoscope II AFM (Digital Instruments, Santa Barbara, CA) used a “J” scanner (horizontal range of 120 um).
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Carmichael, Stephen W. „Atomic Force Microscopy for Biologists“. Microscopy Today 5, Nr. 3 (April 1997): 3–4. http://dx.doi.org/10.1017/s1551929500060193.
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Atomic force microscopy (AFM) has proven to be very useful to material scientists and physicists. Biologists are only beginning to utilize the potential of this methodology. In a recent article, Tatsuo Ushiki, Jiro Hitomi, Shigeaki Ogura, Takeshi Umemoto, and Masatsugu Shigeno reviewed the applications of AFM to biologic studies.They began by reviewing the basic principles of AFM, emphasizing the value of the non-contact mode for visualizing the relatively “soft” surface of biologic specimens. They presented some examples of biologic images: DNA, chromosomes, and collagen fibrils. The specimens examined with the AFM did not need to be coated, theoretically offering a view with a smaller potential for artifacts. AFM images have the advantage of containing quantitative information about the sample height.
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Jalili, Nader, Mohsen Dadfarnia und Darren M. Dawson. „A Fresh Insight Into the Microcantilever-Sample Interaction Problem in Non-Contact Atomic Force Microscopy“. Journal of Dynamic Systems, Measurement, and Control 126, Nr. 2 (01.06.2004): 327–35. http://dx.doi.org/10.1115/1.1767852.
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The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements of intermolecular forces with atomic-resolution characterization that can be employed in a broad spectrum of applications. The non-contact AFM offers unique advantages over other contemporary scanning probe techniques such as contact AFM and scanning tunneling microscopy, especially when utilized for reliable measurements of soft samples (e.g., biological species). Current AFM imaging techniques are often based on a lumped-parameters model and ordinary differential equation (ODE) representation of the micro-cantilevers coupled with an adhoc method for atomic interaction force estimation (especially in non-contact mode). Since the magnitude of the interaction force lies within the range of nano-Newtons to pica-Newtons, precise estimation of the atomic force is crucial for accurate topographical imaging. In contrast to the previously utilized lumped modeling methods, this paper aims at improving current AFM measurement technique through developing a general distributed-parameters base modeling approach that reveals greater insight into the fundamental characteristics of the microcantilever-sample interaction. For this, the governing equations of motion are derived in the global coordinates via the Hamilton’s Extended Principle. An interaction force identification scheme is then designed based on the original infinite dimensional distributed-parameters system which, in turn, reveals the unmeasurable distance between AFM tip and sample surface. Numerical simulations are provided to support these claims.
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Yoo, Ryan YK. „The Story behind the First Automatic Atomic Force Microscope“. Microscopy Today 30, Nr. 2 (März 2022): 40–45. http://dx.doi.org/10.1017/s1551929522000463.
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Abstract:Over the past three decades, atomic force microscopy (AFM) has undergone a series of design changes to attain a flat XY scan and stable non-contact mode in ambient atmosphere. AFM has evolved into an ideal method for non-destructive scanning of samples with longer probe tip life, high accuracy, repeatability, and automation. Together with self-optimizing algorithms for scan parameters in the non-contact mode, AFM can become as widely adopted as other microscopies such as optical or scanning electron microscopy (SEM). Even full automation of AFM probe tip exchange is now possible with probe type recognition software and laser beam alignment on the cantilever and position-sensitive photo diode (PSPD). By separating the optics stage from the Z stage, an AFM system can be made with low mechanical noise and improved optical vision.
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Laflör, Linda, Michael Reichling und Philipp Rahe. „Protruding hydrogen atoms as markers for the molecular orientation of a metallocene“. Beilstein Journal of Nanotechnology 11 (22.09.2020): 1432–38. http://dx.doi.org/10.3762/bjnano.11.127.
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A distinct dumbbell shape is observed as the dominant contrast feature in the experimental data when imaging 1,1’-ferrocene dicarboxylic acid (FDCA) molecules on bulk and thin film CaF2(111) surfaces with non-contact atomic force microscopy (NC-AFM). We use NC-AFM image calculations with the probe particle model to interpret this distinct shape by repulsive interactions between the NC-AFM tip and the top hydrogen atoms of the cyclopentadienyl (Cp) rings. Simulated NC-AFM images show an excellent agreement with experimental constant-height NC-AFM data of FDCA molecules at several tip–sample distances. By measuring this distinct dumbbell shape together with the molecular orientation, a strategy is proposed to determine the conformation of the ferrocene moiety, herein on CaF2(111) surfaces, by using the protruding hydrogen atoms as markers.
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Ho, Huddee J. „Near Contact Mode AFM: Overcoming Surface Fluid Layer In Air And Achieve Ultra-High Resolution“. Microscopy Today 6, Nr. 8 (Oktober 1998): 12–15. http://dx.doi.org/10.1017/s1551929500069170.
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A major goal of Atomic Force Microscopy (AFM) is to achieve nanometer resolution on surface topography, Vibrating cantilever mode (VCM) is an important configuration of an AFU instrument, It was proposed in the first AFM paper.VCM in ultra-high vacuum (UHV) results in true AFM atomic resolution, which reveals atomic scale surface defects such as a single missing atom in a lattice. However, the VCM operation in air has many difficulties due to the surface contamination on the sample and the AFM tip. The most popular operation modes of the VCM are the non-contact mode and the Tapping mode. Both of these have limited lateral resolution in air.
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Rius, Gemma, Matteo Lorenzoni, Soichiro Matsui, Masaki Tanemura und Francesc Perez-Murano. „Boosting the local anodic oxidation of silicon through carbon nanofiber atomic force microscopy probes“. Beilstein Journal of Nanotechnology 6 (19.01.2015): 215–22. http://dx.doi.org/10.3762/bjnano.6.20.
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Many nanofabrication methods based on scanning probe microscopy have been developed during the last decades. Local anodic oxidation (LAO) is one of such methods: Upon application of an electric field between tip and surface under ambient conditions, oxide patterning with nanometer-scale resolution can be performed with good control of dimensions and placement. LAO through the non-contact mode of atomic force microscopy (AFM) has proven to yield a better resolution and tip preservation than the contact mode and it can be effectively performed in the dynamic mode of AFM. The tip plays a crucial role for the LAO-AFM, because it regulates the minimum feature size and the electric field. For instance, the feasibility of carbon nanotube (CNT)-functionalized tips showed great promise for LAO-AFM, yet, the fabrication of CNT tips presents difficulties. Here, we explore the use of a carbon nanofiber (CNF) as the tip apex of AFM probes for the application of LAO on silicon substrates in the AFM amplitude modulation dynamic mode of operation. We show the good performance of CNF-AFM probes in terms of resolution and reproducibility, as well as demonstration that the CNF apex provides enhanced conditions in terms of field-induced, chemical process efficiency.
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Lübbe, Jannis, Matthias Temmen, Philipp Rahe und Michael Reichling. „Noise in NC-AFM measurements with significant tip–sample interaction“. Beilstein Journal of Nanotechnology 7 (01.12.2016): 1885–904. http://dx.doi.org/10.3762/bjnano.7.181.
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The frequency shift noise in non-contact atomic force microscopy (NC-AFM) imaging and spectroscopy consists of thermal noise and detection system noise with an additional contribution from amplitude noise if there are significant tip–sample interactions. The total noise power spectral density D Δ f (f m) is, however, not just the sum of these noise contributions. Instead its magnitude and spectral characteristics are determined by the strongly non-linear tip–sample interaction, by the coupling between the amplitude and tip–sample distance control loops of the NC-AFM system as well as by the characteristics of the phase locked loop (PLL) detector used for frequency demodulation. Here, we measure D Δ f (f m) for various NC-AFM parameter settings representing realistic measurement conditions and compare experimental data to simulations based on a model of the NC-AFM system that includes the tip–sample interaction. The good agreement between predicted and measured noise spectra confirms that the model covers the relevant noise contributions and interactions. Results yield a general understanding of noise generation and propagation in the NC-AFM and provide a quantitative prediction of noise for given experimental parameters. We derive strategies for noise-optimised imaging and spectroscopy and outline a full optimisation procedure for the instrumentation and control loops.
Dissertationen zum Thema "Non-Contact mode Atomic Force Microscopy (nc-AFM)"
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Para, Franck. „Nanostructures organiques en régimes supra-moléculaire et covalent sur substrats diélectriques : propriétés structurales et optiques“. Electronic Thesis or Diss., Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0289.
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Cette thèse porte sur l’étude de l’influence de la structure de la matière à l’échelle atomique sur ses propriétés macroscopiques. Dans ce contexte, l’équipe Nanostructuration de l’IM2NP s’attache à synthétiser et à caractériser des nano-matériaux organiques fonctionnalisés sur surfaces solides. Ce travail se concentre spécifiquement sur l’étude des propriétés structurales et optiques de nanostructures organiques obtenues par croissance sur des substrats diélectriques d’halogénures alcalins mono-cristallins, sous ultra-vide et à température ambiante. Les caractérisations expérimentales sont menées en Microscopie à Force Atomique en mode non-contact (propriétés structurales) et en Spectroscopie de Réflectivité Différentielle (propriétés optiques d’absorption UV-visible). Deux régimes très distincts de croissance ont été étudiés, avec, pour chacun d’eux, des molécules différentes. Le premier système concerne des nanostructures supra-moléculaires de bis-pyrènes sur KCl(001) et NaCl(001). L’étude combinée de leurs propriétés structurales et optiques, depuis le régime sous mono-couche jusqu’au régime multi-couches, permet d’extraire quantitativement la fonction diélectrique des couches aux différents stades de leur croissance. Le second système concerne une thématique plus récemment découverte dans la communauté : la synthèse sur surface (ou polymérisation sur surface), pour laquelle après adsorption, les molécules se lient entre elles de manière covalente, formant ainsides nanostructures plus cohésives qu’en régime supramoléculaire. Nous avons ainsi démontré la formation de structures covalentes par polymérisation radicalaire de dimaléimides sur KCl(001) sous illumination UVThis thesis deals with the study of the influence of the structure of matter at the atomic scale on its macroscopic properties. Thereto, the IM2NP Nanostructuration team masters the synthesis and characterization of functionalized organic nanostructureson solid surfaces. Specifically, this work focuses on the study of the structural and optical properties of organic nanostructures grown on dielectric single-crystalline alkaly halides substrates under ultra-high vacuum and ambient temperature. Experiments are carried out by non-contact Atomic Force Microscopy (structural properties) and by Differential Reflectance Spectroscopy (optical properties of UV-visible absorption). Two distinct growth regimes have been investigated, with different molecules each. The first system involves supramolecular nanostructures of bis-pyrenes molecules grown on KCl(001) and NaCl(001). The combined study of their structural and optical properties, from the sub-monolayer to the multilayer regime, allows us to quantitatively extract the dielectric function of the layers at the different stages of their growth. The second system deals with a more recent topic in the surface science community, namely on-surface synthesis. In this case, upon adsorption, the molecules bind together covalently, which results in nanostructures that are more cohesive than in the supramolecular regime. We have evidenced the formation of covalent structures by free-radical polymers of dimaleimide on KCl(001) under UV illumination
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Spadafora, Evan. „Etude par microscopie à force atomique en mode non contact et microscopie à sonde de Kelvin, de matériaux modèles pour le photovoltaïque organique“. Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00647312.
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La nanostructure et les propriétés électroniques de matériaux modèles pour le photovoltaïque organique, ont été étudiées en utilisant la Microscopie à Force Atomique en mode non contact sous ultra-vide (NC-AFM) et la Microscopie à sonde de Kelvin (KPFM). En utilisant le mode modulation d'amplitude (AM-KPFM), le potentiel de surface photo- généré dans des mélanges donneur-accepteur présentant une ségrégation de phase optimale a pu être visualisé à l'échelle du nanomètre. Afin de préciser la nature des forces mises en jeu dans le processus d'imagerie KPFM, des oligomères π-conjugués auto-assemblés ont ensuite été étudiés. Une transition entre régimes à longue et à courte portée a ainsi été mise en évidence en combinant l'imagerie en haute résolution aux mesures de spectroscopie en distance. Ces mesures ont également démontré que l'influence des forces électrostatiques à courte portée peut être minimisée en travaillant au seuil du contraste de dissipation. Enfin cette procédure a été utilisée, en combinaison avec les mesures de spectroscopie de photoélectrons UV, pour analyser la fonction de sortie locale d'électrodes transparentes à base de nanotubes de carbone fonctionnalisés.
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Vecchiola, Aymeric. „Développement d’une imagerie de résistance électrique locale par AFM à pointe conductrice en mode contact intermittent“. Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112058/document.
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Le microscope à force atomique (AFM) permet de caractériser avec une excellente résolution spatiale les surfaces d’échantillons de différentes natures et peut être mis en œuvre dans des milieux variés. Cette versatilité a favorisé le développement d’un grand nombre de techniques dérivées, destinées à investiguer diverses propriétés physiques locales. Le LGEP a ainsi réalisé un module, le Résiscope, capable de mesurer la résistance électrique locale à la surface d’un échantillon polarisé en continu, sur une gamme de 11 décades. Mise au point en mode contact, où la pointe exerce en permanence une force sur l’échantillon, cette technique fonctionne très bien sur des matériaux durs, mais trouve ses limites sur des échantillons mous ou fragiles puisque dans certaines conditions, la pointe peut altérer leur surface. Pour de tels échantillons, un mode contact intermittent, dans lequel la pointe vient à intervalles réguliers toucher très brièvement la surface, est plus approprié, mais complique la réalisation des mesures électriques. Le but de la thèse consistait à lever cette difficulté en modifiant le Résiscope pour pouvoir l’associer au « Pulsed Force Mode », mode intermittent où la pointe oscille à une fréquence de 100Hz à 2000Hz.Différentes évolutions matérielles et logicielles ont été apportées pour permettre le suivi temporel détaillé du signal de résistance électrique à chaque établissement/rupture de contact (indispensable pour passer en revue les phénomènes liés à l’intermittence), de même que pour pouvoir travailler à des vitesses de balayage acceptables. Pour l’imagerie, les meilleurs contrastes ont été obtenus grâce à une électronique de synchronisation et de traitement prenant en compte les valeurs de résistance électrique à des moments bien précis. Pour tester ce nouveau système, nous avons dans un premier temps comparé les courbes de résistance et de déflexion que nous obtenons par ce mode avec celles considérées classiquement dans le mode approche-retrait. Nous avons ensuite étudié l’influence des principaux paramètres (fréquence et amplitude d’oscillation, force d’appui, type de pointe, etc.) sur les mesures topographiques et électriques, en utilisant le HOPG comme matériau de référence. Ces essais ont notamment permis de mettre en évidence un retard quasi systématique du signal électrique par rapport au signal de déflexion (autre que le temps de mesure propre au Résiscope), dont nous n’avons pu élucider l’origine. Une fois ces connaissances acquises, nous avons étudié deux types d’échantillons organiques, l’un à caractère académique – des monocouches auto-assemblées d’alcanethiols (SAMs), l’autre à finalité plus applicative – des couches minces formées d’un réseau interpénétré de deux constituants (P3HT:PCBM) destinées aux cellules photovoltaïques. Dans les deux cas nous avons montré la pertinence de l’outil Résiscope en mode intermittent pour obtenir des informations qualitatives et quantitatives. Parallèlement à ces travaux sur matériaux fragiles, nous avons mené une étude annexe sur un phénomène de croissance de matière à caractère isolant constaté dans des conditions particulières sur différents matériaux durs, qui a été interprété comme la formation de polymère de friction sous l’effet des nano-glissements répétés associés à la déflexion du levier.Ces travaux ont été réalisés dans le cadre d’une convention CIFRE avec la société Concept Scientifique Instruments, adossée au projet ANR « MELAMIN » (P2N 2011)The atomic force microscope (AFM) allows to characterize with excellent spatial resolution samples of different types of surfaces and can be implemented in various environments. This versatility has encouraged the development of a large number of derivative technics, intended to investigate various local physical properties. The LGEP thus achieved a module, the Résiscope, capable of measuring the local electrical resistance on the surface of a sample polarized continuously, on a range of 11 decades. Developed in contact mode, where the tip continuously exerts a force on the sample, this technic works well on hard materials, but finds its limits on soft or fragile samples since under certain conditions, the tip can alter the surface. For such samples, an intermittent contact mode, in which the tip comes at regular intervals touch very briefly the surface, is more appropriate, but complicates the achievement of electrical measurements. The aim of this thesis was to overcome this difficulty by changing the Résiscope to be able to join the "Pulsed Force Mode", intermittent mode where the tip oscillates at a frequency of 100Hz to 2000Hz. Different hardware and software changes have been made to permit the detailed temporal monitoring of the electrical resistance signal to each make / break contact (necessary to review the phenomena related to intermittency), as well as to be able to work in acceptable scan speeds. For imaging, the best contrasts were obtained through an electronic timing and treatment taking into account the electrical resistance values at specific times.To test this new system, we have initially compared resistance and deflection curves we get by this mode with those considered classically in the force-distance curves mode. We then investigated the influence of main parameters (frequency and amplitude of oscillation, setpoint, coating of the tips, etc.) on the topographical and electrical measurements, using the HOPG as reference material. These tests resulted to highlight a nearly systematic delay of the electrical signal relative to the deflection signal (other than the Resiscope measure time), which we were not able to elucidate the origin. Once these knowledge acquired, we studied two types of organic samples, one in academic nature - Self-Assembled Monolayers of alkanethiols (SAMs), the other more applicative purpose – formed of thin layers of an interpenetrating network of two components (P3HT:PCBM) for photovoltaic cells. In both cases we have shown the relevance of the Resiscope tool in intermittent mode to obtain qualitative and quantitative information. In addition to these work on fragile materials, we conducted an annex study on a phenomenon of growth material of insulating nature found in special conditions on various hard materials, which has been interpreted as the friction polymer formation as a result of repeatedly nano-sliding associated with the deflection of the cantilever. These investigations were conducted under a CIFRE agreement with the Concept Scientific Instruments company, backed by the ANR MELAMIN» (P2N 2011) project
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Siry, Pierre. „Développement d'un dispositif d'acoustique picoseconde en microscopie optique de champ proche pour l'étude des propriétés élastiques de nano-objets“. Paris 6, 2002. http://www.theses.fr/2002PA066339.
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Olbrich, Reinhard. „NC-AFM studies on CeO2 film and CeO2 crystal surfaces“. Doctoral thesis, 2018. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2018053017217.
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Cerium oxide has become an outstanding material in catalytic applications over the last decades. In this thesis, the morphology and atomic structure of thick cerium oxide films and ceria single crystals is investigated by non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM). The ceria films are prepared by annealing cycles from room temperature up to 1100K in ultra high vacuum (UHV) and in an oxygen atmosphere. The films exhibit large smooth terraces separated predominantly by O-Ce-O triple layer height step edges but in contrast to the ceria single crystals some inhomogeneities are observed on the terraces. By annealing the film at 1020K to 1070K in UHV several intermediate phases can be stabilized ranging from the fully oxidized phase CeO2 to the fully reduced phase Ce2O3. These phases have a unique stoichiometry with regular arranged vacancies in the surface and subsurface as revealed by density functional theory (DFT) calculations. The film can be reoxidized by annealing in an oxygen atmosphere as shown by X-ray spectroscopy (XPS). The annealing in oxygen atmosphere also results in a surface with less inhomogeneities. This makes the ceria films an excellent model system for catalytic applications.
Further in this thesis a measurement series exhibiting absorbed water on the film surface is presented and discussed. Also line defects observed on the film and on the single crystal are analyzed.
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Lübbe, Jannis Ralph Ulrich. „Cantilever properties and noise figures in high-resolution non-contact atomic force microscopy“. Doctoral thesis, 2013. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2013040310741.
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Different methods for the determination of cantilever properties in non-contact atomic force microscopy (NC-AFM) are under investigation. A key aspect is the determination of the cantilever stiffness being essential for a quantitative NC-AFM data analysis including the extraction of the tip-surface interaction force and potential. Furthermore, a systematic analysis of the displacement noise in the cantilever oscillation detection is performed with a special focus on the thermally excited cantilever oscillation. The propagation from displacement noise to frequency shift noise is studied under consideration of the frequency response of the PLL demodulator.
The effective Q-factor of cantilevers depends on the internal damping of the cantilever as well as external influences like the ambient pressure and the quality of the cantilever fixation.
While the Q-factor has a strong dependence on the ambient pressure between vacuum and ambient pressure yielding a decrease by several orders of magnitude, the pressure dependence of the resonance frequency is smaller than 1% for the same pressure range.
On the other hand, the resonance frequency highly depends on the mass of the tip at the end of the cantilever making its reliable prediction from known cantilever dimensions difficult.
The cantilever stiffness is determined with a high-precision static measurement method and compared to dimensional and dynamic methods. Dimensional methods suffer from the uncertainty of the measured cantilever dimensions and require a precise knowledge its material properties. A dynamic method utilising the measurement of the thermally excited cantilever displacement noise to obtain cantilever properties allows to characterise unknown cantilevers but requires an elaborative measurement equipment for spectral displacement noise analysis.
Having the noise propagation in the NC-AFM system fully characterised, a proposed method allows for spring constant determination from the frequency shift noise at the output of the PLL demodulator with equipment already being available in most NC-AFM setups.
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(11013732), Devin M. Kalafut. „Multistability in microbeams: Numerical simulations and experiments in capacitive switches and resonant atomic force microscopy systems“. Thesis, 2021.
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Microelectromechanical systems (MEMS) depend on mechanical deformation to sense their environment, enhance electrical circuitry, or store data. Nonlinear forces arising from multiphysics phenomena at the micro- and nanoscale -- van der Waals forces, electrostatic fields, dielectric charging, capillary forces, surface roughness, asperity interactions -- lead to challenging problems for analysis, simulation, and measurement of the deforming device elements. Herein, a foundation for the study of mechanical deformation is provided through computational and experimental studies of MEMS microcantilever capacitive switches. Numerical techniques are built to capture deformation equilibria expediently. A compact analytical model is developed from principle multiphysics governing operation. Experimental measurements support the phenomena predicted by the analytical model, and finite element method (FEM) simulations confirm device-specific performance. Altogether, the static multistability and quasistatic performance of the electrostatically-actuated switches are confirmed across analysis, simulation, and experimentation.
The nonlinear multiphysics forces present in the devices are critical to the switching behavior exploited for novel applications, but are also a culprit in a common failure mode when the attractive forces overcome the restorative and repulsive forces to result in two elements sticking together. Quasistatic operation is functional for switching between multistable states during normal conditions, but is insufficient under such stiction-failure. Exploration of dynamic methods for stiction release is often the only option for many system configurations. But how and when is release achieved? To investigate the fundamental mechanism of dynamic release, an atomic force microscopy (AFM) system -- a microcantilever with a motion-controlled base and a single-asperity probe tip, measured and actuated via lasers -- is configured to replicate elements of a stiction-failed MEMS device. Through this surrogate, observable dynamic signatures of microcantilever deflection indicate the onset of detachment between the probe and a sample.
Bücher zum Thema "Non-Contact mode Atomic Force Microscopy (nc-AFM)"
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Chen, C. Julian. Introduction to Scanning Tunneling Microscopy. 3. Aufl. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198856559.001.0001.
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The scanning tunnelling microscope (STM) was invented by Binnig and Rohrer and received a Nobel Prize of Physics in 1986. Together with the atomic force microscope (AFM), it enables non-destructive observing and mapping atoms and molecules on solid surfaces down to a picometer resolution. A recent development is the non-destructive observation of wavefunctions in individual atoms and molecules, including nodal structures inside the wavefunctions. STM and AFM have become indespensible instruments for scientists of various disciplines, including physicists, chemists, engineers, and biologists to visualize and utilize the microscopic world around us. Since the publication of the first edition in 1993, this book has been recognized as a standard introduction for everyone that starts working with scanning probe microscopes, and a useful reference book for those more advanced in the field. After an Overview chapter accessible for newcomers at an entry level presenting the basic design, scientific background, and illustrative applications, the book has three Parts. Part I, Principles, provides the most systematic and detailed theory of its scientific bases from basic quantum mechancis and condensed-metter physics in all available literature. Quantitative analysis of its imaging mechanism for atoms, molecules, and wavefunctions is detailed. Part II, Instrumentation, provides down to earth descriptions of its building components, including piezoelectric scanners, vibration isolation, electronics, software, probe tip preparation, etc. Part III, Related methods, presenting two of its most important siblings, scanning tunnelling specgroscopy and atomic force miscsoscopy. The book has five appendices for background topics, and 405 references for further readings.
Buchteile zum Thema "Non-Contact mode Atomic Force Microscopy (nc-AFM)"
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Chen, C. Julian. „Atomic Force Microscopy“. In Introduction to Scanning Tunneling Microscopy, 379–400. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198856559.003.0016.
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This chapter discusses atomic force microscopy (AFM), focusing on the methods for atomic force detection. Although the force detection always requires a cantilever, there are two types of modes: the static mode and the dynamic mode. The general design and the typical method of manufacturing of the cantilevers are discussed. Two popular methods of static force detection are presented. The popular dynamic-force detection method, the tapping mode is described, especially the methods in liquids. The non-contact AFM, which has achieved atomic resolution in the weak attractive force regime, is discussed in detail. An elementary and transparent analysis of the principles, including the frequency shift, the second harmonics, and the average tunneling current, is presented. It requires only Newton’s equation and Fourier analysis, and the final results are analyzed over the entire range of vibrational amplitude. The implementation is briefly discussed.
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Sanders, Wesley C. „Contact Mode AFM“. In Atomic Force Microscopy, 61–72. CRC Press, 2019. http://dx.doi.org/10.1201/9780429266553-5.
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„Contact Mode AFM“. In Fundamentals of Atomic Force Microscopy, 229–59. WORLD SCIENTIFIC, 2015. http://dx.doi.org/10.1142/9789814630368_0008.
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Souier, Tewfik. „Conductive Probe Microscopy Investigation of Electrical and Charge Transport in Advanced Carbon Nanotubes and Nanofibers-Polymer Nanocomposites“. In Handbook of Research on Nanoscience, Nanotechnology, and Advanced Materials, 343–75. IGI Global, 2014. http://dx.doi.org/10.4018/978-1-4666-5824-0.ch014.
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In this chapter, the main scanning probe microscopy-based methods to measure the transport properties in advanced polymer-Carbon Nanotubes (CNT) nanocomposites are presented. The two major approaches to investigate the electrical and charge transport (i.e., Electrostatic Force Microscopy [EFM] and Current-Sensing Atomic Force Microscopy [CS-AFM]) are illustrated, starting from their basic principles. First, the authors show how the EFM-related techniques can be used to provide, at high spatial resolution, a three-dimensional representation CNT networks underneath the surface. This allows the studying of the role of nanoscopic features such as CNTs, CNT-CNT direct contact, and polymer-CNT junctions in determining the overall composite properties. Complementary, CS-AFM can bring insight into the transport mechanism by imaging the spatial distribution of currents percolation paths within the nanocomposite. Finally, the authors show how the CS-AFM can be used to quantify the surface/bulk percolation probability and the nanoscopic electrical conductivity, which allows one to predict the macroscopic percolation model.
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Chen, C. Julian. „Nanomechanical Effects“. In Introduction to Scanning Tunneling Microscopy, 253–72. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198856559.003.0009.
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This chapter discusses the effect of force and deformation of the tip apex and the sample surface in the operation and imaging mechanism of STM and AFM. Because the contact area is of atomic dimension, a very small force and deformation would generate a large measurable effect. Three effects are discussed. First is the stability of the STM junction, which depends on the rigidity of the material. For soft materials, hysterisis is more likely. For rigid materials, the approaching and retraction cycles are continuous and reproducible. Second is the effect of force and deformation to the STM imaging mechanism. For soft material such as graphite, force and deformation can amplify the observed corrugation. For hard materials as most metals, force and deformation can decrease the observed corrugation. Finally, the effect of force and deformation on tunneling barrier height measurements is discussed.
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El Dakkony, Saly R., Mahmoud F. Mubarak und Adel A. H. Abdel-Rahman. „Nanocellulose-based Membranes for Water Purification: Multifunctional Nanocellulose Extraction, Characterization, Modification Strategies, and Current Release in Water Treatment and Environmental Remediation“. In Novel Materials and Water Purification, 101–25. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/9781837671663-00101.
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The environment is a top priority in the 21st century. Much research has focused on renewable water desalination membranes and eco-friendly, sustainable materials from natural sources are being studied more due to their recyclability, biodegradability, compatibility, and benign behavior. Due to its availability, green credentials, and glucose residue chains, nanocellulose (NC) is a potential cellulose-based water-filtering material. NC is a promising sustainable nanomaterial due to its unique structure. Researchers are interested in NC-based green composites because they are lightweight, low cost, low density, of high specific modulus, stable in most solvents, non-toxic adsorbents, abundant, and have outstanding mechanical and physical properties. These materials also guarantee water purification. Fourier-transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and thermogravimetric analysis can reveal the thermal properties, chemical structure, and overall morphology of these materials, which are crucial for their future application. The properties of NC depend on the fiber, environment, production method, and surface modification. NC layer-by-layer coated membranes are particularly promising for their dual-cross-linked, self-healing, and antibacterial properties. Finally, this chapter will discuss the many uses of smart nanocellulosic materials and their challenges and potential.
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Mark, James E., Dale W. Schaefer und Gui Lin. „Some Characterization Techniques Useful for Polysiloxanes“. In The Polysiloxanes. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780195181739.003.0006.
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The general approach used in choosing a polymer suitable for a particular application is: . . . Polymerization ↔ Structure ↔ Properties ↔ Application . . . For example, if one wants a polymer for fire-resistant fabrics, then a polymer with good high-temperature properties is required, which implies aromatic structures, which suggest condensation polymerizations. More relevant here, however, would be that a polymer remains elastomeric at low temperatures. This requirement evokes a polymer with high flexibility (low glass transition temperature), which indicates use of the polymerization techniques used with the polysiloxanes. An example of a relevant optical property is the birefringence of a deformed polymer network. This strain-induced birefringence can be used to characterize segmental orientation, and both Gaussian and non-Gaussian elasticity. Infrared dichroism has also been helpful in this regard. In the case of the crystallizable polysiloxane elastomers, orientation is of critical importance with regard to strain-induced crystallization and the tremendous reinforcement it provides. Segmental orientation has also been characterized by fluorescence polarization, deuterium nuclear magnetic resonance (NMR), and polarized infrared spectroscopy. Infrared spectroscopy has been used to characterize the structures of silica-filled polydimethylsiloxane (PDMS). Other optical and spectroscopic techniques are also important, including positron annihilation lifetime spectroscopy, spectroscopic ellipsometry, confocal Raman spectroscopy, and photoluminescence spectroscopy. Surface-enhanced Raman spectroscopy has been made tunable using gold nanorods and strain control on elastomeric PDMS substrates. A great deal of information is now being obtained on filler dispersion and other aspects of elastomer structure and morphology through the use of scanning probe microscopy, which consists of several approaches. One approach is that of scanning tunneling microscopy (STM), in which an extremely sharp metal tip on a cantilever is passed along the surface while measuring the electric current flowing through quantum mechanical tunneling. Monitoring the current then permits maintaining the probe at a fixed height above the surface. Display of probe height as a function of surface coordinates then gives the desired topographic map. One limitation of this approach is the requirement that the sample be electrically conductive. Atomic force microscopy (AFM), on the other hand, does not require a conducting Surface.
Konferenzberichte zum Thema "Non-Contact mode Atomic Force Microscopy (nc-AFM)"
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Belardinelli, Pierpaolo, Abhilash Chandrashekar, Farbod Alijani und Stefano Lenci. „Non-Smooth Dynamics of Tapping Mode Atomic Force Microscopy“. In ASME 2022 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/detc2022-88005.
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Abstract This paper investigates the nonlinear dynamics in tapping-mode atomic force microscopy (AFM) with tip-surface interactions that include Van der Waals and Derjaguin-Müller-Toporov contact forces. We study the periodic solutions of the hybrid system by performing numerical pseudo-arclength continuation. The overall dynamical response scenario is evaluated via bifurcation loci maps in the set of parameters of the discontinuous model. We showcase the influence of different dissipation mechanisms activated when the AFM is in contact or out-of contact with the sample. The robustness of the stable solution in the repulsive regime is studied via local and global analyses. The impacting non-smooth dynamics framed within a higher-mode Galerkin discretization is able to capture windows of irregular and complex motion.
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Laxminarayana, Karthik, und Nader Jalili. „A Review of Recent Developments in Atomic Force Microscopy Systems With Application to Manufacturing and Biological Processes“. In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41170.
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The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements of microstructural parameters and intermolecular forces at nanoscale level with atomic-resolution characterization. Typically, these microcantilever systems are operated in three open-loop modes; non-contact mode, contact mode, and tapping mode. In order to probe electric, magnetic, and/or atomic forces of a selected sample, the non-contact mode is utilized by moving the cantilever slightly away from the sample surface and oscillating the cantilever at or near its natural resonance frequency. Alternatively, the contact mode acquires sample attributes by monitoring interaction forces while the cantilever tip remains in contact with the target sample. The tapping mode of operation combines qualities of both the contact and non-contact modes by gleaning sample data and oscillating the cantilever tip at or near its natural resonance frequency while allowing the cantilever tip to impact the target sample for a minimal amount of time. Recent research on AFM systems has focused on many fabrication and manufacturing processes at molecular levels due to its tremendous surface microscopic capabilities. This paper provides a review of such recent developments in AFM imaging systems with emphasis on operational modes, microcantilever dynamic modeling and control. Due to the important contributions of AFM systems to manufacturing, this paper also provides a comprehensive review of recent applications of different AFM systems in these important areas.
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Jalili, Nader, Mohsen Dadfarnia und Darren M. Dawson. „Distributed-Parameters Base Modeling and Vibration Analysis of Micro-Cantilevers Used in Atomic Force Microscopy“. In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/vib-48502.
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The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements of intermolecular forces with atomic-resolution characterization that can be employed in a broad spectrum of applications such as electronics, semi-conductors, materials, manufacturing, polymers, biological analysis, and biomaterials. The noncontact AFM offers unique advantages over other contemporary scanning probe techniques such as contact AFM and scanning tunneling microscopy. Current AFM imaging techniques are often based on a lumped-parameters model and ordinary differential equation (ODE) representation of the micro-cantilevers coupled with an ad-hoc method for atomic interaction force estimation (especially in non-contact mode). Since the magnitude of the interaction force lies within the range of nano-Newtons to pica-Newtons, precise estimation of the atomic force is crucial for accurate topographical imaging. In contrast to the previously utilized lumped modeling methods, this paper aims at improving current AFM measurement technique through developing a general distributed-parameters base modeling approach that reveals greater insight into the fundamental characteristics of the microcantilever-sample interaction. For this, the governing equations of motion are derived in the global coordinates via the Hamilton’s Extended Principle. By properly selecting a set of general coordinates, the resulting non-homogenous boundary value problem is then converted to a homogenous one, and hence, analytically solvable. The AFM controller can then be designed based on the original infinite dimensional distributed-parameters system which, in turn, removes some of the disadvantages associated with the truncated-model base controllers such as control spillovers, residual oscillations and increased order of the control. Numerical simulations are provided to support these claims.
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Pishkenari, H. N., Nader Jalili und A. Meghdari. „Acquisition of High Precision Images for Non-Contact Atomic Force Microscopy via Direct Identification of Sample Height“. In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81627.
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Atomic force microscopes (AFM) can image and manipulate sample properties at the atomic scale. The non-contact mode of AFM offers unique advantages over other contemporary scanning probe techniques, especially when utilized for reliable measurements of soft samples (e.g., biological species). The distance between cantilever tip and sample surface is a time varying parameter even for a fixed sample height, and hence, difficult to identify. A remedy to this problem is to directly identify the sample height in order to generate high precision, atomic-resolution images. For this, the microcantilever is modeled by a single mode approximation and the interaction between the sample and cantilever is derived from a van der Waals potential. Since in most practical applications only the microcantilever deflection is accessible, this measurement is utilized to identify the sample height in each point. Using the proposed approach for identification of the sample height, the scanning speed can be increased significantly. Furthermore, for taking atomic-scale images of atomically flat samples, there is no need to use the feedback loop to achieve setpoint amplitude. Simulation results are provided to demonstrate the effectiveness of the approach and suggest the most suitable technique for the sample height identification.
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Burson, Kristen M., Mahito Yamamoto und William G. Cullen. „High Resolution Microscopy of SiO2 and the Structure of SiO2-Supported Graphene“. In ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-48737.
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Graphene has attracted great interest due to its exceptional electrical, mechanical, and chemical properties since its discovery in 2004. Since its first realization, the substrate of choice for graphene exfoliation has been Si wafer with approximately 300 nm thick SiO2 dielectric layer, because it allows 1) direct optical detection of monolayer flakes, and 2) a convenient back gate with dielectric for controlling carrier density in the graphene. However, the amorphous structure of SiO2 and its associated surface roughness has led to ongoing controversy in determining the structure of SiO2-supported graphene. The conductivity of graphene allows scanning tunneling microscopy (STM) to be used to measure its topography, generally allowing its structure to be atomically resolved. In contrast, the insulating SiO2 must be probed with atomic force microscopy (AFM), and this is often done using ambient tapping-mode AFM. STM measurements of graphene on SiO2 generally show greater roughness and finer corrugation than is seen in AFM measurements of SiO2, and this has been interpreted as evidence for “intrinsic” corrugation of the graphene. However, when the energetics of adhesion and elasticity are considered, the idea of intrinsic structure becomes quite controversial for graphene supported on a substrate. Here we show that UHV non-contact AFM (NC-AFM) measurement of SiO2 reveals structure unresolved in previous measurements, and shows both greater roughness and smaller lateral feature size than seen for graphene measured by STM. High-resolution measurement of the SiO2 topography enables an analysis based on the energetics of graphene bending and adhesion, showing that the graphene structure is highly conformal to the SiO2 beneath it. The topographies reported here contrast the atomically-flat crystalline surfaces used in benchmark NC-AFM measurements. They pose unique challenges for measurement resolution, and highlight the very different physical mechanisms which determine resolution in STM vs. NC-AFM. We discuss these issues and our recent efforts at quantitative modeling of the imaging process, with particular focus on the role of van der Waals forces and their contribution to the image signal.
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Magonov, Sergei, und John D. Alexander. „Multifrequency Approaches in Characterization of Materials With Single-Pass Kelvin Force Microscopy“. In ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-29225.
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This article presents an implementation of high-resolution imaging in Kelvin force microscopy (KFM) using the multi-frequency approach in the intermittent contact mode. The basic function of atomic force microscopy – high resolution imaging of surface topography is usually performed in the resonant oscillatory modes: amplitude modulation or frequency modulation. When a conducting probe is applied in the AFM-related electric modes it senses also the electrostatic tip-sample forces. Simultaneous and separate detection of the mechanical and electrostatic forces can be realized by using the probe response at different resonant and non-resonant frequencies. In KFM, a nullification of the electrostatic force is applied for detection of a local surface potential. The described experimental set-up and procedures help us to reveal the surface potential variations with high sensitivity and spatial resolution. The examples of KFM studies of metals, semiconductors and molecular systems with dipole moments demonstrate how this technique can be applied for advanced and quantitative characterization of heterogeneous systems.
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Nikooienejad, Nastaran, Mohammad Maroufi und S. O. Reza Moheimani. „A Novel Non-Raster Scan Method for AFM Imaging“. In ASME 2018 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/dscc2018-9049.
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We report a new non-raster scan method based on a rosette pattern for high-speed atomic force microscopy (AFM). In this method, the lateral axes of the scanner are driven by the sum of two sinusoids with identical amplitudes and different frequencies. We formulate the problem so as to generate the rosette pattern and calculate scan parameters and resolution. To achieve high performance tracking, a controller is designed based on the internal model principle. The controller includes the dynamic modes of the reference signals and higher harmonics to cope with the system nonlinearities. We conduct an experiment employing the proposed method and a two degree of freedom microelectromechanical system nanopositioner to scan a circular-shaped area with a diameter of 6μm in 0.2 sec. The steady state tracking error is less than 4.48nm, i.e. only 9% of the selected resolution. AFM scanning is performed in contact mode constant height and high quality images are obtained.
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Pishkenari, Hossein Nejat, und Ali Meghdari. „The Atomic-Scale Hysteresis in Non Contact Atomic Force Microscopy“. In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24683.
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In this research, the hysteresis in the tip-sample interaction force in noncontact force microscopy (NC-AFM) is measured with the aid of atomistic dynamics simulations. The observed hystersis in the interaction force and displacement of the system atoms leads to the loss of energy during imaging of the sample surface. Using molecular dynamics simulations it is shown that the mechanism of the energy dissipation occurs due to bistabilities caused by atomic jumps of the surface and tip atoms in the contact region. The conducted simulations demonstrate that when a gold coated nano probe is brought close to the Au (001) surface, the tip apex atom jumps to the surface; and instantaneously, four surface atoms jump away from the surface toward the tip apex atom. Along this line, particular attention is dedicated to the dependency of the energy loss to different parameters such as the environment temperature, the tip orientation, the surface plane direction, the system size, the distance of the closest approach and the tip oscillation frequency.
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Arafat, Haider N., Ali H. Nayfeh und Elihab M. Abdel-Rahman. „Modal Interactions in Contact-Mode Atomic Force Microscopes“. In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14938.
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Atomic force microscopes (AFM) are used to estimate material and surface properties. When using contact-mode AFM, the specimen or the probe is excited near a natural frequency of the system to estimate the linear coefficient of the contact stiffness. Because higher modes offer lower thermal noise, higher quality factors, and higher sensitivity to stiff samples, their use in this procedure is more desirable. However, these modes are candidates for internal resonances, where the energy being fed into one mode may be channeled to another mode. If such interactions are ignored, the results obtained from the probe may be distorted. The method of multiple scales is used to derive an approximate analytical expression to the probe response in the presence of two-to-one autoparametric resonance between the second and third modes. We examine characteristics of this solution in relation to a single-mode response and consider its implications in AFM measurements.
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Stark, R. W. „Force Feedback in Dynamic Atomic Force Microscopy“. In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81264.
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The feedback perspective of dynamic AFM provides a powerful tool to investigate the non-linear system dynamics from a system theoretic point of view. Including the higher order dynamics of the extended cantilever beam in the model the contact resonances can be reproduced faithfully without the need to solve the partial differential equation of motion directly. The investigation of the non-linear dynamics provides valuable insight into the generation of higher harmonics in dynamic AFM. However, the light lever detection scheme is widely used in dynamic AFM. This means that — strictly speaking — the tip-deflection is not a measurable quantity: the local deflection angle is measured but not the deflection itself. Additionally, time-delays may be introduced into the system influencing the dynamic behavior. Apart from system inherent time delays, a delayed force feedback is often used in order manipulate the system’s resonance characteristics (quality factor). Such an active control of the oscillatory behavior of the cantilever used in atomic force microscopy (AFM) allows one to tune the quality factor to purpose. For experiments requiring a high force sensitivity an enhancement of the quality factor is desirable whereas in time critical experiments additional damping may be needed. In order to control the quality factor a feedback signal is used that approximates the time derivative of the system state within the bandwidth of interest.