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Ricardo Garcia - One of the best experts on this subject based on the ideXlab platform.
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force reconstruction from Tapping Mode force microscopy experiments
Nanotechnology, 2015Co-Authors: Amir Farokh Payam, Daniel Martinjimenez, Ricardo GarciaAbstract:Fast, accurate, and robust nanomechanical measurements are intensely studied in materials science, applied physics, and molecular biology. Amplitude modulation force microscopy (Tapping Mode) is the most established nanoscale characterization technique of surfaces for air and liquid environments. However, its quantitative capabilities lag behind its high spatial resolution and robustness. We develop a general method to transform the observables into quantitative force measurements. The force reconstruction algorithm has been deduced on the assumption that the observables (amplitude and phase shift) are slowly varying functions of the tip–surface separation. The accuracy and applicability of the method is validated by numerical simulations and experiments. The method is valid for liquid and air environments, small and large free amplitudes, compliant and rigid materials, and conservative and non-conservative forces.
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unifying theory of Tapping Mode atomic force microscopy
Physical Review B, 2002Co-Authors: Alvaro San Paulo, Ricardo GarciaAbstract:We propose a general method for describing Tapping-Mode atomic-force microscopy. The combined participation of attractive and repulsive interactions determines the multivalued nature of the resonance curve. This, in turn, implies the coexistence of two different stable oscillations for some excitation frequencies. The coexistence of two stable oscillations depends on the driving force and tip-surface separation. Increasing the driving force inhibits the low-amplitude oscillation state. Because resolution depends on the oscillation state, we propose that the absence of the low amplitude solution is responsible for the inconsistencies observed in high-resolution imaging of biomolecules.
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phase contrast and surface energy hysteresis in Tapping Mode scanning force microsopy
Surface and Interface Analysis, 1999Co-Authors: Ricardo Garcia, Javier Tamayo, Alvaro San PauloAbstract:Phase imaging is one of the most attractive features of Tapping Mode scanning force microscopy operation. In this paper we analyse the relationship between phase contrast imaging and the energy loss due to tip-sample interaction forces. An analytical relationship is obtained between the phase shift and the energy loss. Experiments performed on graphite are in agreement with the analytical expression.
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effects of elastic and inelastic interactions on phase contrast images in Tapping Mode scanning force microscopy
Applied Physics Letters, 1997Co-Authors: Javier Tamayo, Ricardo GarciaAbstract:The dependence of phase contrast in Tapping-Mode scanning force microscopy on elastic and inelastic interactions is studied. The cantilever–tip ensemble is simulated as a driven, damped harmonic oscillator. It is found that for tip–sample elastic interactions, phase contrast is independent of the sample’s elastic properties. However, phase contrast associated with elastic modulus variations are observed if viscous damping or adhesion energy hysteresis is considered during tip–sample contact. The phase shift versus tip–sample equilibrium separation was measured for a compliant material (polypropylene) and for a stiff sample (mica). The agreement obtained between theory and experiment supports the conclusions derived from the Model. These results emphasize the relevance of energy dissipating processes at the nanometer scale to explain phase contrast imaging in Tapping-Mode force microscopy.
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deformation contact time and phase contrast in Tapping Mode scanning force microscopy
Langmuir, 1996Co-Authors: Ricardo GarciaAbstract:The general features of Tapping Mode operation of a scanning force microscope are presented. Relevant factors of Tapping Mode such as forces, deformation, and contact times can be calculated as functions of Tapping frequency, amplitude damping, and sample elastic and viscoelastic properties. Typical contact times per oscillation are about 10-7 s for hard samples and 6 × 10-7 s for soft materials, i.e., between one and two orders of magnitude smaller than their equivalents in contact Mode force microscopy. The Model proposed allows the determination of the phase lag between excitation signal and cantilever response. Major factors to phase contrast are viscoelastic properties and adhesion forces with little participation from elastic properties. Experiments performed on droplets of glycerin deposited on graphite illustrate the ability to image them by recording phase changes.
Din Ping Tsai - One of the best experts on this subject based on the ideXlab platform.
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Implementation of a short‐tip Tapping‐Mode tuning fork near‐field scanning optical microscope
Journal of Microscopy, 2003Co-Authors: N H Lu, C W Huang, C Y Chen, C F Yu, Y H Fu, Din Ping TsaiAbstract:Summary We present the implementation of a short-tip Tapping-Modetuning fork near-field scanning optical microscope. Tappingfrequency dependences of the piezoelectric signal amplitudesfor a bare tuning fork fixed on the ceramic plate, a short-tipTapping-Mode tuning fork scheme and an ordinary Tapping-Mode tuning fork configuration with an 80-cm optical fibreattached are demonstrated and compared. Our experimentalresults show that this new short-tip Tapping-Mode tuning forkscheme provides a stable and high Q factor at the Tappingfrequency of the tuning fork and will be very helpful when longoptical fibre probes have to be used in an experiment. Bothcollection and excitation Modes of short-tip Tapping-Mode tun-ing fork near-field scanning optical microscope are appliedto study the near-field optical properties of a single-Modetelecommunication optical fibre and a green InGaN/GaNmultiquantum well light-emitting diode. Introduction Advances in nanoscience and nanotechnology advocate rapidprogress in new techniques and instruments which have theability to perform nanoscale fabrication or to offer high spatialresolution characterization down to the nanometre dimen-sion. Owing to its versatile applications in nanostructurefabrication (Massanell
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DESIGN AND CONSTRUCTION OF A SHORT-TIP Tapping-Mode TUNING FORK NEAR-FIELD SCANNING OPTICAL MICROSCOPE
International Journal of Nanoscience, 2003Co-Authors: C W Huang, Din Ping Tsai, N H Lu, C Y Chen, C F Yu, Y H Fu, Pei WangAbstract:The design and construction of a Tapping-Mode tuning fork with a short fiber probe as the force sensing element for near-field scanning optical microscopy is reported. This type of near-field scanning optical microscopy provides a stable and high Q factor at the Tapping frequency of the tuning fork, and thus gives high quality NSOM and AFM images of samples. We present results obtained by using the short tip Tapping-Mode tuning fork near-field scanning optical microscopy measurements performed on the endfaces of a single Mode telecommunication optical fiber and a silica-based buried channel waveguide.
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Short fiber probe scheme for Tapping-Mode tuning fork near-field scanning optical microscopy
Nano-Optics and Nano-Structures, 2002Co-Authors: C W Huang, Din Ping Tsai, N H Lu, C Y Chen, C F Yu, Pei WangAbstract:Construction of a Tapping-Mode tuning fork with a short fiber probe as the force sensing element for near-field scanning optical microscopy is reported. This type of near-field scanning optical microscopy provides stable and high Q factor at the Tapping frequency of the tuning fork, and thus gives high quality NSOM and AFM images of samples. We present results obtained by using the short tip Tapping-Mode tuning fork near-field scanning optical microscopy measurements performed on a single Mode telecommunication optical fiber and a silica based buried channel waveguide.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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Tapping Mode tuning fork force sensing for near field scanning optical microscopy
Applied Physics Letters, 1998Co-Authors: Din Ping Tsai, Yuan Ying LuAbstract:A Tapping-Mode tuning fork force-sensing method for near-field scanning optical microscope is reported. Use of the Tapping-Mode tuning fork with mechanically asymmetric excitation generates better stability and sensitivity than in the shear force Mode. Comparison of force curves for the two methods demonstrate that the Tapping-Mode tuning fork method provides a simpler and more sensitive method for near-field measurements. The method is demonstrated by imaging a sample consisting of 500 nm standard polystyrene spheres on silica in both air and water.
J P Cleveland - One of the best experts on this subject based on the ideXlab platform.
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high speed Tapping Mode imaging with active q control for atomic force microscopy
Applied Physics Letters, 2000Co-Authors: Todd Sulchek, J D Adams, J P Cleveland, Stephen C. Minne, Abdullah Atalar, Goksen G Yaralioglu, C F Quate, Robert W Hsieh, Dennis M Adderton, E GutierrezAbstract:The speed of Tapping Mode imaging with the atomic force microscope (AFM) has been increased by over an order of magnitude. The enhanced operation is achieved by (1) increasing the instrument’s mechanical bandwidth and (2) actively controlling the cantilever’s dynamics. The instrument’s mechanical bandwidth is increased by an order of magnitude by replacing the piezotube z-axis actuator with an integrated zinc oxide (ZnO) piezoelectric cantilever. The cantilever’s dynamics are optimized for high-speed operation by actively damping the quality factor (Q) of the cantilever. Active damping allows the amplitude of the oscillating cantilever to respond to topography changes more quickly. With these two advancements, 80μm×80 μm high-speed Tapping Mode images have been obtained with a scan frequency of 15 Hz. This corresponds to a tip velocity of 2.4 mm/s.
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linearity of amplitude and phase in Tapping Mode atomic force microscopy
Physical Review B, 2000Co-Authors: Murti V Salapaka, Degang J Chen, J P ClevelandAbstract:In this article Tapping-Mode atomic force microscope dynamics is studied. The existence of a periodic orbit at the forcing frequency is shown under unrestrictive conditions. The dynamics is further analyzed using the impact Model for the tip-sample interaction and a spring-mass-damper Model of the cantilever. Stability of the periodic orbit is established. Closed-form expressions for various variables important in Tapping-Mode imaging are obtained. The linear relationship of the amplitude and the sine of the phase of the first harmonic of the periodic orbit with respect to cantilever-sample offset is shown. The study reinforces gentleness of the TappingMode on the sample. Experimental results are in excellent qualitative agreement with the theoretical predictions. The linear relationship of the sine of the phase and the amplitude can be used to infer sample properties. The comparison between the theory and the experiments indicates essential features that are needed in a more refined Model.
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Harmonic analysis based Modeling of Tapping-Mode AFM
Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999Co-Authors: A. Sebastian, M.v. Salapaka, D.j. Chen, J P ClevelandAbstract:In this paper we use harmonic balance and averaging techniques to analyze the Tapping Mode dynamics of the atomic force microscope (AFM). A Model for the cantilever sample interaction is developed. Experimental results show that the analysis and the Model predict the behavior of the Tapping cantilever.
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energy dissipation in Tapping Mode atomic force microscopy
Applied Physics Letters, 1998Co-Authors: J P Cleveland, B Anczykowski, A E Schmid, Virgil B ElingsAbstract:A method is presented to measure the energy dissipated by the tip–sample interaction in Tapping-Mode atomic force microscopy (AFM). The results show that if the amplitude of the cantilever is held constant, the sine of the phase angle of the driven vibration is then proportional to changes in the tip–sample energy dissipation. This means that images of the cantilever phase in Tapping-Mode AFM are closely related to maps of dissipation. The maximum dissipation observed for a 4 N/m cantilever with an initial amplitude of 25 nm Tapping on a hard substrate at 74 kHz is about 0.3 pW.
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Tapping Mode atomic force microscopy in liquids
Applied Physics Letters, 1994Co-Authors: Paul K Hansma, J P Cleveland, Manfred Radmacher, Deron Walters, P E Hillner, Magdalena Bezanilla, Monika Fritz, Helen G Hansma, Craig Prater, J MassieAbstract:Tapping Mode atomic force microscopy in liquids gives a substantial improvement in imaging quality and stability over standard contact Mode. In Tapping Mode the probe‐sample separation is modulated as the probe scans over the sample. This modulation causes the probe to tap on the surface only at the extreme of each modulation cycle and therefore minimizes frictional forces that are present when the probe is constantly in contact with the surface. This imaging Mode increases resolution and reduces sample damage on soft samples. For our initial experiments we used a Tapping frequency of 17 kHz to image deoxyribonucleic acid plasmids on mica in water. When we imaged the same sample region with the same cantilever, the plasmids appeared 18 nm wide in contact Mode and 5 nm in Tapping Mode.
Todd Sulchek - One of the best experts on this subject based on the ideXlab platform.
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improving Tapping Mode atomic force microscopy with piezoelectric cantilevers
Ultramicroscopy, 2004Co-Authors: B. Rogers, Todd Sulchek, L. Manning, Jesse AdamsAbstract:Abstract This article summarizes improvements to the speed, simplicity and versatility of Tapping Mode atomic force microscopy (AFM). Improvements are enabled by a piezoelectric microcantilever with a sharp silicon tip and a thin, low-stress zinc oxide (ZnO) film to both actuate and sense deflection. First, we demonstrate self-sensing Tapping Mode without laser detection. Similar previous work has been limited by unoptimized probe tips, cantilever thicknesses, and stress in the piezoelectric films. Tests indicate self-sensing amplitude resolution is as good or better than optical detection, with double the sensitivity, using the same type of cantilever. Second, we demonstrate self-oscillating Tapping Mode AFM. The cantilever's integrated piezoelectric film serves as the frequency-determining component of an oscillator circuit. The circuit oscillates the cantilever near its resonant frequency by applying positive feedback to the film. We present images and force-distance curves using both self-sensing and self-oscillating techniques. Finally, high-speed Tapping Mode imaging in liquid, where electric components of the cantilever require insulation, is demonstrated. Three cantilever coating schemes are tested. The insulated microactuator is used to simultaneously vibrate and actuate the cantilever over topographical features. Preliminary images in water and saline are presented, including one taken at 75.5 μm/s—a threefold improvement in bandwidth versus conventional piezotube actuators.
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Improving Tapping Mode atomic force microscopy with piezoelectric cantilevers
Ultramicroscopy, 2004Co-Authors: B. Rogers, Todd Sulchek, L. Manning, J D AdamsAbstract:This article summarizes improvements to the speed, simplicity and versatility of Tapping Mode atomic force microscopy (AFM). Improvements are enabled by a piezoelectric microcantilever with a sharp silicon tip and a thin, low-stress zinc oxide (ZnO) film to both actuate and sense deflection. First, we demonstrate self-sensing Tapping Mode without laser detection. Similar previous work has been limited by unoptimized probe tips, cantilever thicknesses, and stress in the piezoelectric films. Tests indicate self-sensing amplitude resolution is as good or better than optical detection, with double the sensitivity, using the same type of cantilever. Second, we demonstrate self-oscillating Tapping Mode AFM. The cantilever's integrated piezoelectric film serves as the frequency-determining component of an oscillator circuit. The circuit oscillates the cantilever near its resonant frequency by applying positive feedback to the film. We present images and force-distance curves using both self-sensing and self-oscillating techniques. Finally, high-speed Tapping Mode imaging in liquid, where electric components of the cantilever require insulation, is demonstrated. Three cantilever coating schemes are tested. The insulated microactuator is used to simultaneously vibrate and actuate the cantilever over topographical features. Preliminary images in water and saline are presented, including one taken at 75.5μm/s - a threefold improvement in bandwidth versus conventional piezotube actuators. © 2004 Elsevier B.V. All rights reserved.
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high speed Tapping Mode atomic force microscopy in liquid using an insulated piezoelectric cantilever
Review of Scientific Instruments, 2003Co-Authors: B. Rogers, S. Malekos, David York, B Beneschott, Todd Sulchek, K. Murray, J D Adams, L. Manning, M. Jones, H CavazosAbstract:Quicker imaging times for Tapping Mode atomic force microscopy in liquid could provide a real-time imaging tool for studying dynamic phenomena in physiological conditions. We demonstrate faster imaging speed using microcantilevers with integrated piezoelectric actuators. The exposed electric components of the cantilever necessitate an insulation scheme for use in liquid; three coating schemes have been tested. Preliminary Tapping Mode images have been taken using the insulated microactuator to simultaneously vibrate and actuate the cantilever over topographical features in liquid, including a high speed image of steps on a mica surface in water and an image of two e coli bacteria taken in saline solution at 75.5 μm/s, a threefold improvement in bandwidth versus conventional piezotube actuators.
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High speed Tapping Mode atomic force microscopy in liquid using an insulated piezoelectric cantilever
Review of Scientific Instruments, 2003Co-Authors: B. Rogers, S. Malekos, David York, B Beneschott, Todd Sulchek, K. Murray, J D Adams, L. Manning, H CavazosAbstract:Quicker imaging times for Tapping Mode atomic force microscopy in liquid could provide a real-time imaging tool for studying dynamic phenomena in physiological conditions. We demonstrate faster imaging speed using microcantilevers with integrated piezoelectric actuators. The exposed electric components of the cantilever necessitate an insulation scheme for use in liquid; three coating schemes have been tested. Preliminary Tapping Mode images have been taken using the insulated microactuator to simultaneously vibrate and actuate the cantilever over topographical features in liquid, including a high speed image of steps on a mica surface in water and an image of two e coli bacteria taken in saline solution at 75.5 μm/s, a threefold improvement in bandwidth versus conventional piezotube actuators. © 2003 American Institute of Physics.
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characterization and optimization of scan speed for Tapping Mode atomic force microscopy
Review of Scientific Instruments, 2002Co-Authors: Todd Sulchek, Goksen G Yaralioglu, C F Quate, Stephen C. MinneAbstract:Increasing the imaging speed of Tapping Mode atomic force microscopy (AFM) has important practical and scientific applications. The scan speed of Tapping-Mode AFMs is limited by the speed of the feedback loop that maintains a constant Tapping amplitude. This article seeks to illuminate these limits to scanning speed. The limits to the feedback loop are: (1) slow transient response of probe; (2) instability limitations of high-quality factor (Q) systems; (3) feedback actuator bandwidth; (4) error signal saturation; and the (5) rms-to-dc converter. The article will also suggest solutions to mitigate these limitations. These limitations can be addressed through integrating a faster feedback actuator as well as active control of the dynamics of the cantilever.
Stephen C. Minne - One of the best experts on this subject based on the ideXlab platform.
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self sensing Tapping Mode atomic force microscopy
Sensors and Actuators A-physical, 2005Co-Authors: Jesse Adams, B. Rogers, L. Manning, M. Jones, Stephen C. MinneAbstract:We demonstrate self-sensing Tapping Mode using commercially available, low-stress, piezoelectric cantilevers with sharp, integrated, silicon tips. Previous work has been limited by stress in the cantilevers, thickness and size of the cantilevers, un-optimized electrical trace design, and/or a lack of a probing tip. Tests indicate amplitude resolution with self-sensing to be as good or better than optical detection, and sensitivities up to twice as good, with the same type cantilever. A Tapping Mode image of an evaporated gold film and force curves that compare optical and self-sensing detection methods are presented.
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Self-oscillating Tapping Mode atomic force microscopy
Review of Scientific Instruments, 2003Co-Authors: L. Manning, B. Rogers, M. Jones, Jesse Adams, J. L. Fuste, Stephen C. MinneAbstract:A piezoelectric microcantilever probe is demonstrated as a self-oscillator used for Tapping Mode atomic force microscopy. The integrated piezoelectric film on the cantilever serves as the frequency-determining component of an oscillator circuit; oscillation near the cantilever’s resonant frequency is maintained by applying positive feedback to the film via this circuit. This new Mode, which is a step towards more compact and parallel Tapping Mode AFM imaging, is demonstrated by imaging an evaporated gold film on a silicon substrate. A self-oscillating frequency spectrum and a force–distance curve are also presented.
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characterization and optimization of scan speed for Tapping Mode atomic force microscopy
Review of Scientific Instruments, 2002Co-Authors: Todd Sulchek, Goksen G Yaralioglu, C F Quate, Stephen C. MinneAbstract:Increasing the imaging speed of Tapping Mode atomic force microscopy (AFM) has important practical and scientific applications. The scan speed of Tapping-Mode AFMs is limited by the speed of the feedback loop that maintains a constant Tapping amplitude. This article seeks to illuminate these limits to scanning speed. The limits to the feedback loop are: (1) slow transient response of probe; (2) instability limitations of high-quality factor (Q) systems; (3) feedback actuator bandwidth; (4) error signal saturation; and the (5) rms-to-dc converter. The article will also suggest solutions to mitigate these limitations. These limitations can be addressed through integrating a faster feedback actuator as well as active control of the dynamics of the cantilever.
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high speed Tapping Mode imaging with active q control for atomic force microscopy
Applied Physics Letters, 2000Co-Authors: Todd Sulchek, J D Adams, J P Cleveland, Stephen C. Minne, Abdullah Atalar, Goksen G Yaralioglu, C F Quate, Robert W Hsieh, Dennis M Adderton, E GutierrezAbstract:The speed of Tapping Mode imaging with the atomic force microscope (AFM) has been increased by over an order of magnitude. The enhanced operation is achieved by (1) increasing the instrument’s mechanical bandwidth and (2) actively controlling the cantilever’s dynamics. The instrument’s mechanical bandwidth is increased by an order of magnitude by replacing the piezotube z-axis actuator with an integrated zinc oxide (ZnO) piezoelectric cantilever. The cantilever’s dynamics are optimized for high-speed operation by actively damping the quality factor (Q) of the cantilever. Active damping allows the amplitude of the oscillating cantilever to respond to topography changes more quickly. With these two advancements, 80μm×80 μm high-speed Tapping Mode images have been obtained with a scan frequency of 15 Hz. This corresponds to a tip velocity of 2.4 mm/s.
