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Graphite–castor oil polyurethane composite electrode surfaces – AFM morphological and electrochemical characterisation

Chiorcea-Paquim, Ana-Maria; Diculescu, Victor Constantin; Cervini, Priscila; Cavalheiro, Eder Tadeu Gomes; Brett, Ana Maria Oliveira
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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Graphite–castor oil polyurethane composite electrodes with different graphite weight percentages, 30–70% graphite–polyurethane w w−1, were morphologically studied by atomic force microscopy (AFM) and voltammetry. AFM images and r.m.s. roughness measurements demonstrated that the polyurethane roughness decreased with increasing the graphite content, composites of 50% and 60% graphite–polyurethane w w−1 showing the smother electrode surface. The electrochemical characterisation was performed in solutions of K4Fe(CN)6 by cyclic voltammetry and impedance spectroscopy. For compositions of 60% and 70% graphite–polyurethane w w−1, the cyclic voltammetry results showed the K4Fe(CN)6 system reversibility. The charge transfer resistance, determined from the EIS spectra, decreased significantly with increasing the graphite/polyurethane ratio, and the capacitance increased for higher graphite percentages. AFM and voltammetric results enable to conclude that 60% graphite–polyurethane w w−1 was the optimal composition for the preparation of the graphite–polyurethane composite electrodes.

Deposition of selenium thin layers on gold surfaces from sulphuric acid media: Studies using electrochemical quartz crystal microbalance, cyclic voltammetry and AFM

CABRAL, Murilo Feitosa; PEDROSA, Valber A.; MACHADO, Sergio Antonio Spinola
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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In this paper we report here new considerations about the relationship between the mass and charge variations (m/z relationship) in underpotential deposition (UPD), bulk deposition and also in the H(2)Se formation reaction. Nanogravimetric experiments were able to show the adsorption of H(2)SeO(3) on the AuO surface prior to the voltammetric sweep and that, after the AuO reduction, 0.40 monolayer of H(2)SeO(3) remains adsorbed on the newly reduced Au surface, which was enough to gives rise to the UPD layer. The UPD results indicate that the maximum coverage with Se(ads) on polycrystalline gold surface corresponds to approximately 0.40 monolayer, in good agreement with charge density results. The cyclic voltammetry experiments demonstrated that the amount of bulk Se obtained during the potential scan to approximately 2 Se monolayers, which was further confirmed by electrochemical quartz crystal microbalance (EQCM) measurements that pointed out a mass variation corresponding of 3 monolayers of Se. In addition, the Se thin films were obtained by chronoamperometric experiments, where the Au electrode was polarized at +0.10V during different times in 1.0 M H(2)SO(4) + 1.0 mM SeO(2). The topologic aspects of the electrodeposits were observed in Atomic Force Microscope (AFM) measurements. Finally...

XRD, AFM, IR and TGA study of nanostructured hydroxyapatite

Mir, Mirta; Leite, Fabio Lima; Herrmann Junior, Paulo Sérgio de Paula; Pissetti, Fabio Luiz; Rossi, Alexandre Malta; Moreira, Elizabeth Lima; Mascarenhas, Yvonne Primerano
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.683052%
In this work, the synthetic hydroxyapatite (HAP) was studied using different preparation routes to decrease the crystal size and to study the temperature effect on the HAP nano-sized hydroxyapatite crystallization. X-ray diffraction (XRD) analysis indicated that all samples were composed by crystalline and amorphous phases . The sample with greater quantity of amorphous phase (40% of total mass) was studied. The nano-sized hydroxyapatite powder was heated and studied at 300, 500, 700, 900 and 1150 °C. All samples were characterized by XRD and their XRD patterns refined using the Rietveld method. The crystallites presented an anisotropic form, being larger in the [001] direction. It was observed that the crystallite size increased continuously with the heating temperature and the eccentricity of the ellipsoidal shape changed from 2.75 at 300 °C to 1.94, 1.43, 1.04 and 1.00 respectively at 500, 700, 900 and 1150 °C. In order to better characterize the morphology of the HAP the samples were also examined using atomic force microscopy (AFM), infrared spectrometry (IR) and thermogravimetric analysis (TGA).

Nano-oxidação do silício utilizando sonda de AFM.; Silicon nano-oxidation using AFM tips.

Pinto, Diego Kops
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 12/07/2007 PT
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A oxidação anódica local utilizando o Microscópio de Força Atômica (AFM - Atomic Force Microscopy) foi investigada aplicando-se uma tensão negativa entre sonda de nitreto de silício e superfícies de Si. Todas as amostras foram limpas em uma solução de 1 NH4OH (30%): 1H2O2 (38%): 4H2O(DI) a 80ºC conhecida na literatura como SC1 (Standard Cleaning 1) ou, alternativamente, uma imersão em solução diluída de ácido hidrofluorídrico seguido de SC1 ou fervura em álcool isopropílico. As nano-oxidações consistiram de padrões quadrados localizados de óxido com área de 0,25 µm² e foram obtidos através do crescimento de linhas paralelas com espaço e comprimento interlinear constante (<2 nm) e várias varreduras dos quadrados em uma mesma área. Das análises de AFM, foram obtidos perfis transversais e 3D, os quais foram empregados na obtenção da espessura do óxido como função da tensão aplicada, número de varreduras e intervalo de tempo após a limpeza SC1. Foi observado que a espessura aumenta com a tensão negativa aplicada e com o número de varreduras. Também foram realizadas simulações para levantar as distribuições de tensão e de campo elétrico no sistema sonda-ar-silício ou sonda-ar-óxido-silício(substrato). Observou-se uma oxidação local assistida por um alto campo elétrico capaz de induzir difusão iônica local finita na extremidade da sonda. Foi simulado também o efeito das diferentes terminações de sonda do AFM...

Síntese de nanotubos de carbono orientados e aplicação na produção de pontas de AFM; Oriented growth of carbon nanotubes and application in production of afm Tips

Fernandes, Fernando Massa
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 09/05/2008 PT
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Neste trabalho foram obtidos nanotubos de carbono de paredes múltiplas (MWNT). O crescimento apresentou alta densidade de nanotubos orientados perpendicularmente à superfície do substrato, com cerca de 20 m de comprimento e diâmetros entre cerca de 20 e 60 nm. Foram utilizados filmes catalisadores contendo ferro, depositados a partir de solução de nitrato de ferro (Fe(NO3)3.9H2O) em álcool etílico com concentrações que variaram entre 37 mmol/L e 1,2 mmol/L. Não foram notadas diferenças significativas entre os nanotubos crescidos com diferentes concentrações, com exceção da solução de 0,6 mmol/L onde não foi observado o crescimento de nanotubos. Os crescimentos de nanotubos de carbono foram efetuados em um reator CVD a plasma de microonda. Os resultados de espectroscopia Raman sugerem que os nanotubos de carbono obtidos neste trabalho correspondem a MWNT, apresentando alto grau de desordem estrutural. Foram realizados crescimentos diretos de nanotubos de carbono sobre as pontas comerciais de AFM, utilizando filmes de nitrato de ferro. Os nanotubos crescidos nas pontas apresentaram tendência em formarem aglomerados. Não foram obtidas pontas de AFM satisfatórias com este método. Outro método consistiu no crescimento de nanotubos de carbono em amostras planas de silício...

On a control design to an AFM microcantilever beam, operating in a tapping-mode, with irregular behavior

Dos Santos Rodrigues, Kleber; Balthazar, José Manoel; Tusset, Angelo Marcelo; Pontes Jr., Bento Rodrigues
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 491-500
ENG
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In last decades, control of nonlinear dynamic systems became an important and interesting problem studied by many authors, what results the appearance of lots of works about this subject in the scientific literature. In this paper, an Atomic Force Microscope micro cantilever operating in tapping mode was modeled, and its behavior was studied using bifurcation diagrams, phase portraits, time history, Poincare maps and Lyapunov exponents. Chaos was detected in an interval of time; those phenomena undermine the achievement of accurate images by the sample surface. In the mathematical model, periodic and chaotic motion was obtained by changing parameters. To control the chaotic behavior of the system were implemented two control techniques. The SDRE control (State Dependent Riccati Equation) and Time-delayed feedback control. Simulation results show the feasibility of the bothmethods, for chaos control of an AFM system. Copyright © 2011 by ASME.

Tm-afm nonlinear motion control with robustness analysis to parametric errors in the control signal determination

Balthazar, Jose Manoel; Tusset, Angelo Marcelo; Bueno, Atila Madureira
Fonte: Polish Soc Theoretical & Applied Mechanics Publicador: Polish Soc Theoretical & Applied Mechanics
Tipo: Artigo de Revista Científica Formato: 93-106
ENG
Relevância na Pesquisa
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Processo FAPESP: 13/04101-6; Nonlinear motion of the microcantilever probe in the Atomic Force Microscope (AFM) has been extensively studied considering mainly the van der Waals forces. Since the behavior of the microcantilever is vital to quality of generated images, the study of control strategies that force the probe to avoid undesired behavior such as chaotic motion, is also of significant importance. A number of published works has shown that the microcantilever is subject to chaotic motion for a certain combination of parameters. For such a parameter combination, the control system must suppress the chaotic motion. Here, an study of the AFM mathematical model is presented, aiming to find a region of operation of the AFM where the motion is chaotic. In order to suppress the chaotic motion, a periodic orbit of the system is obtained, and the controller forces the system to that periodic orbit. Two control strategies are used, namely: The State Dependent Riccati Equation (SDRE) and the Optimal Linear Feedback Control (OLFC). Both control strategies consider the complete nonlinearities of the system...

AFM study of morphology and mechanical properties of a chimeric 2 spider silk and bone sialoprotein protein for bone regeneration

Gomes, Sílvia C.; Numata, Keiji; Leonor, I. B.; Mano, J. F.; Reis, R. L.; Kaplan, David
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Artigo de Revista Científica
Publicado em /05/2011 ENG
Relevância na Pesquisa
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Atomic force microscopy (AFM) was used to assess a new chimeric protein consisting of a fusion protein of the consensus repeat for Nephila clavipes spider dragline protein and bone sialoprotein (6merþBSP). The elastic modulus of this protein in film form was assessed through force curves, and film surface roughness was also determined. The results showed a significant difference among the elastic modulus of the chimeric silk protein, 6merþBSP, and control films consisting of only the silk component (6mer). The behavior of the 6merþBSP and 6mer proteins in aqueous solution in the presence of calcium (Ca) ions was also assessed to determine interactions between the inorganic and organic components related to bone interactions, anchoring, and biomaterial network formation. The results demonstrated the formation of protein networks in the presence of Ca2þ ions, characteristics that may be important in the context of controlling materials assembly and properties related to bone formation with this new chimeric silk-BSP protein.

Morphological analysis of polymers on hair fibers by SEM and AFM

Monteiro,Valéria Fernandes; Natal,Aline Martins Duboc; Soledade,Luís Edmundo Bastos; Longo,Elson
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2003 EN
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The polyquaternium 7® polymer is widely used in cosmetic formulations. Morphologic alterations in hair fibers were observed after the application of the polyquaternium 7® polymer, using SEM and AFM. Continuous applications of this product indicated that it accumulates on the fibers, improving the aspect of the hair surface. Quantitative analysis of the images obtained by AFM was undertaken. The data obtained for the hair surface roughness indicates that the fibers treated with the polymer presented higher roughness than the untreated hair fibers.

XRD, AFM, IR and TGA study of nanostructured hydroxyapatite

Mir,Mirta; Leite,Fabio Lima; Herrmann Junior,Paulo Sérgio de Paula; Pissetti,Fabio Luiz; Rossi,Alexandre Malta; Moreira,Elizabeth Lima; Mascarenhas,Yvonne Primerano
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2012 EN
Relevância na Pesquisa
36.683052%
In this work, the synthetic hydroxyapatite (HAP) was studied using different preparation routes to decrease the crystal size and to study the temperature effect on the HAP nano-sized hydroxyapatite crystallization. X-ray diffraction (XRD) analysis indicated that all samples were composed by crystalline and amorphous phases . The sample with greater quantity of amorphous phase (40% of total mass) was studied. The nano-sized hydroxyapatite powder was heated and studied at 300, 500, 700, 900 and 1150 °C. All samples were characterized by XRD and their XRD patterns refined using the Rietveld method. The crystallites presented an anisotropic form, being larger in the [001] direction. It was observed that the crystallite size increased continuously with the heating temperature and the eccentricity of the ellipsoidal shape changed from 2.75 at 300 °C to 1.94, 1.43, 1.04 and 1.00 respectively at 500, 700, 900 and 1150 °C. In order to better characterize the morphology of the HAP the samples were also examined using atomic force microscopy (AFM), infrared spectrometry (IR) and thermogravimetric analysis (TGA).

Measuring bacterial cells size with AFM

Osiro,Denise; Bernardes Filho,Rubens; Assis,Odilio Benedito Garrido; Jorge,Lúcio André de Castro; Colnago,Luiz Alberto
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2012 EN
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Atomic Force Microscopy (AFM) can be used to obtain high-resolution topographical images of bacteria revealing surface details and cell integrity. During scanning however, the interactions between the AFM probe and the membrane results in distortion of the images. Such distortions or artifacts are the result of geometrical effects related to bacterial cell height, specimen curvature and the AFM probe geometry. The most common artifact in imaging is surface broadening, what can lead to errors in bacterial sizing. Several methods of correction have been proposed to compensate for these artifacts and in this study we describe a simple geometric model for the interaction between the tip (a pyramidal shaped AFM probe) and the bacterium (Escherichia coli JM-109 strain) to minimize the enlarging effect. Approaches to bacteria immobilization and examples of AFM images analysis are also described.

Chemical functionalization of AFM cantilevers; Chemical functionalization of atomic force microscopy cantilevers

Lee, Sunyoung, S.M. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 52 p.; 3055388 bytes; 3056447 bytes; application/pdf; application/pdf
ENG
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Atomic force microscopy (AFM) has been a powerful instrument that provides nanoscale imaging of surface features, mainly of rigid metal or ceramic surfaces that can be insulators as well as conductors. Since it has been demonstrated that AFM could be used in aqueous environment such as in water or various buffers from which physiological condition can be maintained, the scope of the application of this imaging technique has been expanded to soft biological materials. In addition, the main usage of AFM has been to image the material and provide the shape of surface, which has also been diversified to molecular-recognition imaging - functional force imaging through force spectroscopy and modification of AFM cantilevers. By immobilizing of certain molecules at the end of AFM cantilever, specific molecules or functionalities can be detected by the combination of intrinsic feature of AFM and chemical modification technique of AFM cantilever. The surface molecule that is complementary to the molecule at the end of AFM probe can be investigated via specificity of molecule-molecule interaction.; (cont.) Thus, this AFM cantilever chemistry, or chemical functionalization of AFM cantilever for the purpose of chemomechanical surface characterization...

Charakterisierung bio- und chemosensitiver Schichten mit Ellipsometrie und AFM; Characterization of bio- and chemosensitive layers by ellipsometry and AFM

Mutschler, Tina
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
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In dieser Dissertation wurden bio- und chemosensitive Schichten mit Ellipsometrie und AFM charakterisiert. Ellipsometrie ist eine Messmethode, um Schichtdicke und Brechungsindex von dünnen Schichten und Schichtsystemen im Nanometer bis Mikrometerbereich unabhängig voneinander zu bestimmen. Die Atomkraftmikroskopie (AFM) ist eine Methode, um Oberflächentopographien abzubilden. Mit diesen Methoden wurde Makrolon, als chemosensitive Schicht, charakterisiert und anschließend wurde die größenselektive Eigenschaft des mikroporösen Makrolons anhand von ellipsometrischen Messungen unter Analyteinfluss bestimmt und bestätigt. Des Weiteren wurden Polyethylengklykolschichten (PEG) und Amindodextranschichten (AMD) auf ihre Oberflächenbelegungseigenschaften und ihr Quellverhalten in flüssigem Medium charakterisiert. Auf diesen PEG- und AMD-Schichten wurden dann anschließend DNA-Hybridisierungen und Biotin-Streptavidin-Wechselwirkungen charakterisiert. Als weiterer Themenschwerpunkt innerhalb dieser Dissertation stand die Charakterisierung einer bioaktiven dentalen Implantatoberfläche. Diese Implantatoberfläche wurde mit einem Protein modifiziert, das das Anheftungs- und Wachstumsverhalten von Zellen begünstigt. Dieses Schichtsystem wurde ebenfalls mit Ellipsometrie und AFM charakterisiert.; The task of this dissertation was the characterization of bio- and chemosensitive layersystems by ellipsometry and AFM. Ellipsometry is a method of measurement to determine layer thickness and refractive index of thin layers or layer systems within the nanaometer to micrometer scale independently from each other. Atomic force microscopy (AFM) is a method to image surface topographies. Makrolon as a chemosensitive layer was characterized with these methods and subsequently its microporous attribute was validated by ellipsometric measurements under the influence of analyte. Furthermore Polyethyleneglycole and Aminodextrane layers were characterized concerning their surface occupation and their swelling behavior in liquid medium. On these PEG- and AMD-layers DNA-hybridizations and Biotin-Streptavidin interactions were determined. As a further focal point stood the characterization of a bioactive dental implant layer system. This implant surface was modified with a protein that assists cell adhesion and spreading. This layersystem was also characterized with ellipsometry and AFM.

Modeling peak interaction forces of soft matter with dynamic AFM in liquid

Vargas Guzmán, Horacio Andrés
Fonte: Universidade Autônoma de Madrid Publicador: Universidade Autônoma de Madrid
Tipo: Tese de Doutorado
SPA; ENG
Relevância na Pesquisa
27.256003%
Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica de la Materia Condensada. Fecha de lectura: 23-10-2014; The atomic force microscope (AFM) is an instrument that has revolutionized the field of nanoscience and nanotechnology by enabling the characterization and manipulation of materials with nanometer (one billionth of a meter), molecular and atomic resolution. In the last 28 years a variety of experimental AFM techniques have been developed that go from contact to dynamic AFM modes or from working in air to liquid environments. A relevant research avenue within dynamic AFM modes is devoted to the generation of atomic and molecular resolution images of soft materials 1 in liquid environments. Whereby different applications are envisioned into areas of medicine (nanomedicine) and advanced materials. The research presented here focus on two dynamic AFM methods: amplitude modulation AFM (AM-AFM) and Bimodal AM. This thesis describes the study of the peak interaction forces of soft materials under low-Q environments imaged with AM-AFM and Bimodal AM. The peak/maximum interaction forces have been chosen because it rapidly enables tracking into the degree of invasiveness on the sample...

Deformation and nano-rheology of red blood cells: An AFM investigation

Bremmell, Kristin Elizabeth; Evans, Allan Mark; Prestidge, Clive Allan
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
36.683052%
Interaction forces, deformation and nano-rheology of individual red blood cells in physiologically relevant solution conditions have been determined by colloid probe atomic force microscopy (AFM). On approach of the physically immobilised cell and silica glass spherical probe surfaces, deformation of the red blood cell was observed in the force curves. At low levels of deformation, spring constants were determined in the range 3–6 mN m⁻¹, whereas for higher levels of deformation, the forces increase non-linearly and on retraction, significant force curve hysteresis is observed (i.e. lower forces upon retraction). The extent of force curve hysteresis was dependent on both the drive velocity and loading force, typical of a viscoelastic system. The response of the red blood cell has been described by viscoelastic theory, where the short and long time scale elastic moduli and relaxation times are determined, i.e. the cell's nano-rheological properties elucidated. In addition to a time independent elastic modulus of 4.0 × 10³ Nm⁻² at low levels of deformation, time-dependent elastic moduli ranges are observed (3.5 × 10⁴ to 5.5 × 104 Nm⁻² at intermediate levels of deformation and 1.5 × 10⁵ to 3.0 × 10⁵ Nm⁻² at higher levels of deformation). That is...

Towards CNC Automation in AFM Probe-Based Nano Machining

BROUSSEAU, Emmanuel; ARNAL, Benoit; THIERY, Stéphane; NYIRI, Eric; GIBARU, Olivier; MAYOR, J.Rhett
Fonte: University of Wisconsin-Madison Publicador: University of Wisconsin-Madison
EN
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This paper presents a feasibility study, which aims to demonstrate the applicability of the CNC automation philosophy for the process of AFM probe-based nano machining conducted on commercial AFM instruments. In particular, it is proposed to machine in this way nanostructures generated with any CAD software via the representation of tip path trajectories with G-code instructions. Such a representation can then be interpreted with a post processor at the interface of an AFM instrument. To demonstrate the validity of the proposed approach, it was implemented on a complex pattern. The results obtained open further research perspectives with respect to minimizing the sources of machining errors observed.

Crecimiento selectivo de InAs sobre substratos grabados de GaAs(001) mediante litografía de oxidación local por AFM

Martín-Sánchez, Javier
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Tesis Formato: 14834629 bytes; application/pdf
SPA
Relevância na Pesquisa
36.683052%
Tesis leída el 29 de mayo de 2009 en el Departamento de Física de la Materia Condensada de la Universidad Autónoma de Madrid.; Los puntos cuánticos (QDs) de material semiconductor presentan una distribución en su densidad de niveles de energía accesibles tipo delta de Dirac, de modo similar al espectro de niveles energéticos discretos que presenta un átomo, por lo que también se les conoce con la denominación de átomos artificiales. Esta peculiar característica junto con el desarrollo de avanzadas técnicas de fabricación, han permitido la mejora de dispositivos opto-electrónicos, así como el desarrollo de nuevos dispositivos, mediante la inserción en su zona activa bien de capas con QDs, o bien de QDs aislados. Entre los dispositivos basados en QDs aislados, se encuentran los dispositivos emisores de fotones individuales, los cuales están englobados fundamentalmente dentro del campo de la óptica cuántica, y tienen aplicaciones en criptografía cuántica o para el procesamiento de información cuántica. Para integrar de una manera eficiente estas nanoestructuras de punto cuántico en dispositivos emisores de fotones individuales reales es esencial controlar tanto el tamaño (longitud de onda de emisión) como la posición de los QDs. En este trabajo de tesis se presenta una aproximación tecnológica mediante la cual pueden obtenerse QDs de InAs sobre substratos grabados de GaAs(001) con control en los lugares de formación de dichos QDs...

Confining Electrochemical Reactions with an AFM

Martínez Garrido, Ramsés Valentín
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Vídeo Formato: 30547972 bytes; video/mpeg
ENG
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Video didáctico que complementa la Tesis leída el 22 de julio de 2009 en el Departamento de Física de la Materia Condensada de la Facultad de Ciencias de la Universidad Autónoma de Madrid. Para visualizar la tesis completa haga clic en la url de la versión del editor.; Uno de los retos científicos y tecnológicos actuales consiste en el diseño, la fabricación y la operación de dispositivos formados por unos pocos átomos. Para convertir este reto en una realidad es necesario desarrollar técnicas de litografía que permitan la fabricación de dispositivos con dimensiones inferiores a 10nm. El Microscopio de Fuerzas Atómicas (AFM) basa su funcionamiento en la detección de fuerzas a escala atómica mediante la medida óptica de la deflexión de una micropalanca muy sensible, que tiene situada una punta de forma piramidal en su extremo. Aunque la principal aplicación de este microscopio consiste en la caracterización topográfica de superficies, su versatilidad y precisión le han convertido en una importante herramienta para la fabricación de nanoestructuras. En esta tesis se desarrolla y optimiza una técnica de nanofabricación basada en el confinamiento de reacciones químicas que permite la fabricación de motivos de tamaño inferior a los 10nm. Estas nanoestructuras fabricadas con el AFM se utilizarán como centros de atracción electrostática para diferentes tipos de moléculas permitiendo su deposición preferencial. Finalmente...

Nanomask Fabrication by Local oxidation AFM

Martínez Garrido, Ramsés Valentín
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Vídeo Formato: 13912068 bytes; video/mpeg
ENG
Relevância na Pesquisa
36.812517%
Video didáctico que complementa la Tesis leída el 22 de julio de 2009 en el Departamento de Física de la Materia Condensada de la Facultad de Ciencias de la Universidad Autónoma de Madrid. Para visualizar la tesis completa haga clic en la url de la versión del editor; Uno de los retos científicos y tecnológicos actuales consiste en el diseño, la fabricación y la operación de dispositivos formados por unos pocos átomos. Para convertir este reto en una realidad es necesario desarrollar técnicas de litografía que permitan la fabricación de dispositivos con dimensiones inferiores a 10nm. El Microscopio de Fuerzas Atómicas (AFM) basa su funcionamiento en la detección de fuerzas a escala atómica mediante la medida óptica de la deflexión de una micropalanca muy sensible, que tiene situada una punta de forma piramidal en su extremo. Aunque la principal aplicación de este microscopio consiste en la caracterización topográfica de superficies, su versatilidad y precisión le han convertido en una importante herramienta para la fabricación de nanoestructuras. En esta tesis se desarrolla y optimiza una técnica de nanofabricación basada en el confinamiento de reacciones químicas que permite la fabricación de motivos de tamaño inferior a los 10nm. Estas nanoestructuras fabricadas con el AFM se utilizarán como centros de atracción electrostática para diferentes tipos de moléculas permitiendo su deposición preferencial. Finalmente...

AFM Observations of Latent Fission Tracks on Surfaces: Amorphous SiO 2 and Quartz

Espinosa, G.; Golzarri, J I; Vazquez, C; Fragoso, R.; Chadderton, Lewis; Cruz, S.A.
Fonte: Pergamon-Elsevier Ltd Publicador: Pergamon-Elsevier Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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Preliminary results of a systematic AFM experimental investigation of the surface 'track' effects produced by the passage of fission fragments from a californium (252Cf) source into amorphous SiO2 and quartz are described. Fission fragments from the source were collimated using a 10 μm thick aluminum foil and comprised fragments with the usual binary distribution of energies - light and heavy - 79.4 and 103.8 MeV. Irradiations and AFM measurements were carried out in air at normal room temperature and pressure. Remarkably high sputtering yields/fragment were discovered, and in the case of crystalline quartz the ejecta was found to be arranged in an ordered manner. A brief discussion is given of a part likely to be played by electronic energy loss induced Coulomb explosion of target atoms for each point of fragment entry.