Multifrequency spectrum analysis using fully digital G Mode-Kelvin probe force microscopy

International Nuclear Information System (INIS)

Collins, Liam; Belianinov, Alex; Somnath, Suhas; Balke, Nina; Kalinin, Sergei V; Jesse, Stephen; Rodriguez, Brian J

2016-01-01

Since its inception over two decades ago, Kelvin probe force microscopy (KPFM) has become the standard technique for characterizing electrostatic, electrochemical and electronic properties at the nanoscale. In this work, we present a purely digital, software-based approach to KPFM utilizing big data acquisition and analysis methods. General mode (G-Mode) KPFM works by capturing the entire photodetector data stream, typically at the sampling rate limit, followed by subsequent de-noising, analysis and compression of the cantilever response. We demonstrate that the G-Mode approach allows simultaneous multi-harmonic detection, combined with on-the-fly transfer function correction—required for quantitative CPD mapping. The KPFM approach outlined in this work significantly simplifies the technique by avoiding cumbersome instrumentation optimization steps (i.e. lock in parameters, feedback gains etc), while also retaining the flexibility to be implemented on any atomic force microscopy platform. We demonstrate the added advantages of G-Mode KPFM by allowing simultaneous mapping of CPD and capacitance gradient (C′) channels as well as increased flexibility in data exploration across frequency, time, space, and noise domains. G-Mode KPFM is particularly suitable for characterizing voltage sensitive materials or for operation in conductive electrolytes, and will be useful for probing electrodynamics in photovoltaics, liquids and ionic conductors. (paper)

Noise performance of frequency modulation Kelvin force microscopy

Directory of Open Access Journals (Sweden)

Heinrich Diesinger

2014-01-01

Full Text Available Noise performance of a phase-locked loop (PLL based frequency modulation Kelvin force microscope (FM-KFM is assessed. Noise propagation is modeled step by step throughout the setup using both exact closed loop noise gains and an approximation known as “noise gain” from operational amplifier (OpAmp design that offers the advantage of decoupling the noise performance study from considerations of stability and ideal loop response. The bandwidth can be chosen depending on how much noise is acceptable and it is shown that stability is not an issue up to a limit that will be discussed. With thermal and detector noise as the only sources, both approaches yield PLL frequency noise expressions equal to the theoretical value for self-oscillating circuits and in agreement with measurement, demonstrating that the PLL components neither modify nor contribute noise. Kelvin output noise is then investigated by modeling the surrounding bias feedback loop. A design rule is proposed that allows choosing the AC modulation frequency for optimized sharing of the PLL bandwidth between Kelvin and topography loops. A crossover criterion determines as a function of bandwidth, temperature and probe parameters whether thermal or detector noise is the dominating noise source. Probe merit factors for both cases are then established, suggesting how to tackle noise performance by probe design. Typical merit factors of common probe types are compared. This comprehensive study is an encouraging step toward a more integral performance assessment and a remedy against focusing on single aspects and optimizing around randomly chosen key values.

Self-assembled monolayers of alkyl-thiols on InAs: A Kelvin probe force microscopy study

Science.gov (United States)

Szwajca, A.; Wei, J.; Schukfeh, M. I.; Tornow, M.

2015-03-01

We report on the preparation and characterization of self-assembled monolayers from aliphatic thiols with different chain length and termination on InAs (100) planar surfaces. This included as first step the development and investigation of a thorough chemical InAs surface preparation step using a dedicated bromine/NH4OH-based etching process. Ellipsometry, contact angle measurements and atomic force microscopy (AFM) indicated the formation of smooth, surface conforming monolayers. The molecular tilt angles were obtained as 30 ± 10° with respect to the surface normal. Kelvin probe force microscopy (KPFM) measurements in hand with Parameterized Model number 5 (PM5) calculations of the involved molecular dipoles allowed for an estimation of the molecular packing densities on the surface. We obtained values of up to n = 1014 cm- 2 for the SAMs under study. These are close to what is predicted from a simple geometrical model that would calculate a maximum density of about n = 2.7 × 1014 cm- 2. We take this as additional conformation of the substrate smoothness and quality of our InAs-SAM hybrid layer systems.

The importance of cantilever dynamics in the interpretation of Kelvin probe force microscopy.

Science.gov (United States)

Satzinger, Kevin J; Brown, Keith A; Westervelt, Robert M

2012-09-15

A realistic interpretation of the measured contact potential difference (CPD) in Kelvin probe force microscopy (KPFM) is crucial in order to extract meaningful information about the sample. Central to this interpretation is a method to include contributions from the macroscopic cantilever arm, as well as the cone and sharp tip of a KPFM probe. Here, three models of the electrostatic interaction between a KPFM probe and a sample are tested through an electrostatic simulation and compared with experiment. In contrast with previous studies that treat the KPFM cantilever as a rigid object, we allow the cantilever to bend and rotate; accounting for cantilever bending provides the closest agreement between theory and experiment. We demonstrate that cantilever dynamics play a major role in CPD measurements and provide a simulation technique to explore this phenomenon.

Microstructure influence on corrosion behavior of a Fe–Cr–V–N tool alloy studied by SEM/EDS, scanning Kelvin force microscopy and electrochemical measurement

International Nuclear Information System (INIS)

Sababi, Majid; Ejnermark, Sebastian; Andersson, Jörgen; Claesson, Per M.; Pan, Jinshan

2013-01-01

Highlights: ► Localized corrosion of a new N-based tool alloy (Fe–Cr–V–N) has been studied. ► One-pass mode of scanning Kelvin force microscopy (KFM) was used in the study. ► The focus was on correlation between microstructure and localized corrosion. - Abstract: Microstructure influence on corrosion behavior of an N-based tool alloy (Fe–Cr–V–N) has been studied. Electron microscopy analysis showed two types of hard phases in the alloy. One-pass mode scanning Kelvin force microscopy (KFM) was used to investigate relative nobility of the hard phases. Volta potential mapping indicates higher nobility for the hard phases than the alloy matrix, and, the V- and N-rich particles exhibit the highest Volta potential. Post-polarization analysis by SEM revealed localized dissolution initiated in matrix regions adjacent to hard phase particles, and the boundary region surrounding the Cr- and Mo-rich particles is more prone to localized corrosion.

Nanoscale Surface Photovoltage Mapping of 2D Materials and Heterostructures by Illuminated Kelvin Probe Force Microscopy

KAUST Repository

Shearer, Melinda J.

2018-02-01

Nanomaterials are interesting for a variety of applications, such as optoelectronics and photovoltaics. However, they often have spatial heterogeneity, i.e. composition change or physical change in the topography or structure, which can lead to varying properties that would influence their applications. New techniques must be developed to understand and correlate spatial heterogeneity with changes in electronic properties. Here we highlight the technique of surface photovoltage-Kelvin probe force microscopy (SPV-KFM), which is a modified version of non-contact atomic force microscopy capable of imaging not only the topography and surface potential, but also the surface photovoltage on the nanoscale. We demonstrate its utility in probing monolayer WSe2-MoS2 lateral heterostructures, which form an ultrathin p-n junction promising for photovoltaic and optoelectronic applications. We show surface photovoltage maps highlighting the different photoresponse of the two material regions as a result of the effective charge separation across this junction. Additionally, we study the variations between different heterostructure flakes and emphasize the importance of controlling the synthesis and transfer of these materials to obtain consistent properties and measurements.

Nanoscale Surface Photovoltage Mapping of 2D Materials and Heterostructures by Illuminated Kelvin Probe Force Microscopy

KAUST Repository

Shearer, Melinda J.; Li, Ming-yang; Li, Lain-Jong; Jin, Song; Hamers, Robert J

2018-01-01

Nanomaterials are interesting for a variety of applications, such as optoelectronics and photovoltaics. However, they often have spatial heterogeneity, i.e. composition change or physical change in the topography or structure, which can lead to varying properties that would influence their applications. New techniques must be developed to understand and correlate spatial heterogeneity with changes in electronic properties. Here we highlight the technique of surface photovoltage-Kelvin probe force microscopy (SPV-KFM), which is a modified version of non-contact atomic force microscopy capable of imaging not only the topography and surface potential, but also the surface photovoltage on the nanoscale. We demonstrate its utility in probing monolayer WSe2-MoS2 lateral heterostructures, which form an ultrathin p-n junction promising for photovoltaic and optoelectronic applications. We show surface photovoltage maps highlighting the different photoresponse of the two material regions as a result of the effective charge separation across this junction. Additionally, we study the variations between different heterostructure flakes and emphasize the importance of controlling the synthesis and transfer of these materials to obtain consistent properties and measurements.

Microscopic investigation of InGaN/GaN heterostructure laser diode degradation using Kelvin probe force microscopy

International Nuclear Information System (INIS)

Lochthofen, A; Mertin, W; Bacher, G; Furitsch, M; Bruederl, G; Strauss, U; Haerle, V

2008-01-01

We report on Kelvin probe force microscopy (KPFM) measurements on fresh and artificially aged InGaN/GaN laser test structures. In the case of an unbiased laser diode, a comparison of the surface potential between a fresh and a stressed laser diode shows a pronounced modification of the laser facet due to the aging process. Performing KPFM measurements under forward bias, a correlation between the macroscopic I-V characteristics and the microscopic voltage drop across the heterostructure layer sequence is found. This clearly demonstrates the potential of KPFM for investigating InGaN/GaN laser diode degradation

High-resolution noncontact AFM and Kelvin probe force microscopy investigations of self-assembled photovoltaic donor–acceptor dyads

Directory of Open Access Journals (Sweden)

Benjamin Grévin

2016-06-01

Full Text Available Self-assembled donor–acceptor dyads are used as model nanostructured heterojunctions for local investigations by noncontact atomic force microscopy (nc-AFM and Kelvin probe force microscopy (KPFM. With the aim to probe the photo-induced charge carrier generation, thin films deposited on transparent indium tin oxide substrates are investigated in dark conditions and upon illumination. The topographic and contact potential difference (CPD images taken under dark conditions are analysed in view of the results of complementary transmission electron microscopy (TEM experiments. After in situ annealing, it is shown that the dyads with longer donor blocks essentially lead to standing acceptor–donor lamellae, where the acceptor and donor groups are π-stacked in an edge-on configuration. The existence of strong CPD and surface photo-voltage (SPV contrasts shows that structural variations occur within the bulk of the edge-on stacks. SPV images with a very high lateral resolution are achieved, which allows for the resolution of local photo-charging contrasts at the scale of single edge-on lamella. This work paves the way for local investigations of the optoelectronic properties of donor–acceptor supramolecular architectures down to the elementary building block level.

Low-Temperature Reduction of Graphene Oxide: Electrical Conductance and Scanning Kelvin Probe Force Microscopy

Science.gov (United States)

Slobodian, Oleksandr M.; Lytvyn, Peter M.; Nikolenko, Andrii S.; Naseka, Victor M.; Khyzhun, Oleg Yu.; Vasin, Andrey V.; Sevostianov, Stanislav V.; Nazarov, Alexei N.

2018-05-01

Graphene oxide (GO) films were formed by drop-casting method and were studied by FTIR spectroscopy, micro-Raman spectroscopy (mRS), X-ray photoelectron spectroscopy (XPS), four-points probe method, atomic force microscopy (AFM), and scanning Kelvin probe force (SKPFM) microscopy after low-temperature annealing at ambient conditions. It was shown that in temperature range from 50 to 250 °C the electrical resistivity of the GO films decreases by seven orders of magnitude and is governed by two processes with activation energies of 6.22 and 1.65 eV, respectively. It was shown that the first process is mainly associated with water and OH groups desorption reducing the thickness of the film by 35% and causing the resistivity decrease by five orders of magnitude. The corresponding activation energy is the effective value determined by desorption and electrical connection of GO flakes from different layers. The second process is mainly associated with desorption of oxygen epoxy and alkoxy groups connected with carbon located in the basal plane of GO. AFM and SKPFM methods showed that during the second process, first, the surface of GO plane is destroyed forming nanostructured surface with low work function and then at higher temperature a flat carbon plane is formed that results in an increase of the work function of reduced GO.

Electronic properties of dioctylterthiophene-based organic thin-film transistors: A Kelvin probe force microscopy study

International Nuclear Information System (INIS)

Afsharimani, N.; Nysten, B.

2013-01-01

It appeared in the past decades that semi-conducting organic liquid crystals could be used as the active layer in organic thin film transistors (OTFTs). They can be processed by simple methods such as inkjet printing, which paves the way to applications for cheap plastic electronics such as electronic tags, biosensors, and flexible screens. However, the measured field-effect mobility in these OTFTs is relatively low compared to inorganic devices. Generally, such low field-effect mobility values result from extrinsic effects such as grain boundaries or imperfect interfaces with source and drain electrodes. It has been shown that reducing the number of grain boundaries between the source and drain electrodes improves the field effect mobility. Therefore, it is important to understand the transport mechanisms by studying the local structure and electronic properties of organic thin films within the channel and at the interfaces with source and drain electrodes in order to improve the field-effect mobility in OTFTs. Kelvin probe force microscopy (KPFM) is an ideal tool for that purpose since it allows to simultaneously investigate the local structure and the electrical potential distribution in electronic devices. In this work, the structure and the electrical properties of OTFTs based on dioctylterthiophene (DOTT) were studied. The transistors were fabricated by spin-coating DOTT on the transistor structures with untreated and treated (silanized) channel silicon oxide. The potential profiles across the channel and at the metal-electrode interfaces were measured by KPFM. The effect of surface treatment on the electrical properties, charge trapping phenomenon and hysteresis effects is demonstrated and analyzed. - Highlights: • Kelvin probe force microscopy study of organic thin film transistors. • Cost and time savings by using solution processable molecules as active layers. • Smaller crystals and less charge trapping effects in silanized devices. • Decrement

Distinction between magnesium diboride and tetraboride by kelvin probe force microscopy; Unterscheidung von Magnesiumdiborid und Magnesiumtetraborid durch Kelvinsondenkraftmikroskopie

Energy Technology Data Exchange (ETDEWEB)

Kim, Du-Na; Caron, Arnaud; Park, Hai Woong [KoreaTech - Korea Univ. of Technology and Education, Chungnam (Korea, Republic of). School of Energy, Materials and Chemical Engineering

2016-08-15

We analyze mixtures of magnesium diboride and tetraboride synthesized with magnesium powders of different shapes. To distinguish between magnesium diboride and tetraboride we use the contrast of kelvin probe force microscopy. The microstructural morphology strongly depends on the shape of the magnesium powders used in the reaction between magnesium and magnesium tetraboride to form magnesium diboride. With spherical magnesium powder an equiaxed microstructure of magnesium diboride is formed with residual magnesium tetraboride at the grain boundaries. With plate-like magnesium powders elongated magnesium diboride grains are formed. In this case, residual magnesium tetraboride is found to agglomerate.

Investigation of surface potentials in reduced graphene oxide flake by Kelvin probe force microscopy

Science.gov (United States)

Negishi, Ryota; Takashima, Kai; Kobayashi, Yoshihiro

2018-06-01

The surface potential (SP) of reduced graphene oxide (rGO) flakes prepared by thermal treatments of GO under several conditions was analyzed by Kelvin probe force microscopy. The low-crystalline rGO flakes in which a significant amount of oxygen functional groups and structural defects remain have a much lower SP than mechanically exfoliated graphene free from oxygen and defects. On the other hand, the highly crystalline rGO flake after a thermal treatment for the efficient removal of oxygen functional groups and healing of structural defects except for domain boundary shows SP equivalent to that of the mechanically exfoliated graphene. These results indicate that the work function of rGO is sensitively modulated by oxygen functional groups and structural defects remaining after the thermal reduction process, but is not affected significantly by the domain boundary remaining after the healing of structural defects through the thermal treatment at high temperature.

Sample preparation method for scanning force microscopy

CERN Document Server

Jankov, I R; Szente, R N; Carreno, M N P; Swart, J W; Landers, R

2001-01-01

We present a method of sample preparation for studies of ion implantation on metal surfaces. The method, employing a mechanical mask, is specially adapted for samples analysed by Scanning Force Microscopy. It was successfully tested on polycrystalline copper substrates implanted with phosphorus ions at an acceleration voltage of 39 keV. The changes of the electrical properties of the surface were measured by Kelvin Probe Force Microscopy and the surface composition was analysed by Auger Electron Spectroscopy.

Polarity analysis of GaN nanorods by photo-assisted Kelvin probe force microscopy

Energy Technology Data Exchange (ETDEWEB)

Wei, Jiandong; Neumann, Richard; Wang, Xue; Li, Shunfeng; Fuendling, Soenke; Merzsch, Stephan; Al-Suleiman, Mohamed A.M.; Soekmen, Uensal; Wehmann, Hergo-H.; Waag, Andreas [Institut fuer Halbleitertechnik, TU Braunschweig (Germany)

2011-07-15

Polarity dependence (N-polar (000-1) and Ga-polar (0001)) of surface photovoltage of epitaxially grown, vertically aligned GaN nanorods has been investigated by photo-assisted Kelvin probe force microscopy (KPFM). Commercial GaN substrates with known polarities are taken as reference samples. The polarity of GaN substrates can be well distinguished by the change in surface photovoltage upon UV illumination in air ambient. These different behaviors of Ga- and N-polar surfaces are attributed to the polarity-related surface-bound charges and photochemical reactivity. GaN nanorods were grown on patterned SiO{sub 2}/sapphire templates by metal-organic vapor phase epitaxy (MOVPE). In order to analyze the bottom surface of the grown GaN nanorods, a technique known from high power electronics and joining techniques is applied to remove the substrate. The top and bottom surfaces of the GaN nanorods are identified to be N-polar and Ga-polar according to the KPFM results, respectively. Our experiments demonstrate that KPFM is a simple and suitable method capable to identify the polarity of GaN nanorods. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Kelvin probe force microscopy studies of the charge effects upon adsorption of carbon nanotubes and C60 fullerenes on hydrogen-terminated diamond

Science.gov (United States)

Kölsch, S.; Fritz, F.; Fenner, M. A.; Kurch, S.; Wöhrl, N.; Mayne, A. J.; Dujardin, G.; Meyer, C.

2018-01-01

Hydrogen-terminated diamond is known for its unusually high surface conductivity that is ascribed to its negative electron affinity. In the presence of acceptor molecules, electrons are expected to transfer from the surface to the acceptor, resulting in p-type surface conductivity. Here, we present Kelvin probe force microscopy (KPFM) measurements on carbon nanotubes and C60 adsorbed onto a hydrogen-terminated diamond(001) surface. A clear reduction in the Kelvin signal is observed at the position of the carbon nanotubes and C60 molecules as compared with the bare, air-exposed surface. This result can be explained by the high positive electron affinity of carbon nanotubes and C60, resulting in electron transfer from the surface to the adsorbates. When an oxygen-terminated diamond(001) is used instead, no reduction in the Kelvin signal is obtained. While the presence of a charged adsorbate or a difference in work function could induce a change in the KPFM signal, a charge transfer effect of the hydrogen-terminated diamond surface, by the adsorption of the carbon nanotubes and the C60 fullerenes, is consistent with previous theoretical studies.

Potential profile and photovoltaic effect in nanoscale lateral pn junction observed by Kelvin probe force microscopy

International Nuclear Information System (INIS)

Nowak, Roland; Moraru, Daniel; Mizuno, Takeshi; Jablonski, Ryszard; Tabe, Michiharu

2014-01-01

Nanoscale pn junctions have been investigated by Kelvin probe force microscopy and several particular features were found. Within the depletion region, a localized noise area is observed, induced by temporal fluctuations of dopant states. Electronic potential landscape is significantly affected by dopants with ground-state energies deeper than in bulk. Finally, the effects of light illumination were studied and it was found that the depletion region shifts its position as a function of light intensity. This is ascribed to charge redistribution within the pn junction as a result of photovoltaic effect and due to the impact of deepened-level dopants. - Highlights: • In pn nano-junctions, temporal potential fluctuations are found in depletion layer. • Fluctuations are due to frequent capture and emission of free carriers by dopants. • Depletion layer position shifts as a function of the intensity of irradiated light. • The depletion layer shifts are due to changes of deep-level dopants' charge states

Quantitative dopant profiling in semiconductors. A new approach to Kelvin probe force microscopy

Energy Technology Data Exchange (ETDEWEB)

Baumgart, Christine

2012-07-01

Failure analysis and optimization of semiconducting devices request knowledge of their electrical properties. To meet the demands of today's semiconductor industry, an electrical nanometrology technique is required which provides quantitative information about the doping profile and which enables scans with a lateral resolution in the sub-10 nm range. In the presented work it is shown that Kelvin probe force microscopy (KPFM) is a very promising electrical nanometrology technique to face this challenge. The technical and physical aspects of KPFM measurements on semiconductors required for the correct interpretation of the detected KPFM bias are discussed. A new KPFM model is developed which enables the quantitative correlation between the probed KPFM bias and the dopant concentration in the investigated semiconducting sample. Quantitative dopant profiling by means of the new KPFM model is demonstrated by the example of differently structured, n- and p-type doped silicon. Additionally, the transport of charge carriers during KPFM measurements, in particular in the presence of intrinsic electric fields due to vertical and horizontal pn junctions as well as due to surface space charge regions, is discussed. Detailed investigations show that transport of charge carriers in the semiconducting sample is a crucial aspect and has to be taken into account when aiming for a quantitative evaluation of the probed KPFM bias.

Direct observation of crosssectional potential distribution in GaN-based MIS structures by Kelvin-probe force microscopy

Energy Technology Data Exchange (ETDEWEB)

Kaneko, Masamitsu; Kikawa, Junjiroh [Research Organization of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577 (Japan); Fujishima, Tatsuya; Chikamatsu, Kentaro; Yamaguchi, Atsushi; Otake, Hirotaka [Research and Development Headquarters, ROHM Co., Ltd., 21 Saiin Mizosaki-Cho, Ukyo-ku, Kyoto 615-8585 (Japan); Nanishi, Yasushi [Department of Photonics, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577 (Japan)

2009-06-15

Cross-sectional potential distribution in GaN-based trench gate metal-insulator-semiconductor field-effect transistors (MISFET) at off- and operating-state has been investigated by using Kelvin-probe force microscopy to clarify the actual operating situation of trench gate MISFET. The potential distribution reflecting the wafer structure, n/p/n{sup -}/n{sup +}, is observed as shown in the right figure. At the off-state (the gate voltage is fixed to 0 V), it is found that the electric field at the internal p/n{sup -} interface become strong, on the contrary to that at top n/p interface is almost unchanged by the stepwise increase of the drain bias from 0 to 15 V. From the analysis of results obtained at operating state, we can confirm the situation how the channel forms by increasing the gate voltage. This information is useful for designing devices and improving their characteristics (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Direct assessment of p-n junctions in single GaN nanowires by Kelvin probe force microscopy

Science.gov (United States)

Minj, Albert; Cros, Ana; Auzelle, Thomas; Pernot, Julien; Daudin, Bruno

2016-09-01

Making use of Kelvin probe force microscopy, in dark and under ultraviolet illumination, we study the characteristics of p-n junctions formed along the axis of self-organized GaN nanowires (NWs). We map the contact potential difference of the single NW p-n junctions to locate the space charge region and directly measure the depletion width and the junction voltage. Simulations indicate a shrinkage of the built-in potential for NWs with small diameter due to surface band bending, in qualitative agreement with the measurements. The photovoltage of the NW/substrate contact is studied by analyzing the response of NW segments with p- and n-type doping under illumination. Our results show that the shifts of the Fermi levels, and not the changes in surface band bending, are the most important effects under above band-gap illumination. The quantitative electrical information obtained here is important for the use of NW p-n junctions as photovoltaic or rectifying devices at the nanoscale, and is especially relevant since the technique does not require the formation of ohmic contacts to the NW junction.

Detection of secondary phases in duplex stainless steel by magnetic force microscopy and scanning Kelvin probe force microscopy

Energy Technology Data Exchange (ETDEWEB)

Ramírez-Salgado, J. [Instituto Mexicano del Petróleo, Dirección de Investigación y Posgrado, Eje Central Norte Lázaro Cárdenas, No. 152, 07730 D.F., México (Mexico); Domínguez-Aguilar, M.A., E-mail: madoming@imp.mx [Instituto Mexicano del Petróleo, Dirección de Investigación y Posgrado, Eje Central Norte Lázaro Cárdenas, No. 152, 07730 D.F., México (Mexico); Castro-Domínguez, B. [University of Tokyo, Department of Chemical System Engineering, Faculty of Engineering Bldg. 5, 7F 722, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113–8656 (Japan); Hernández-Hernández, P. [Instituto Mexicano del Petróleo, Dirección de Investigación y Posgrado, Eje Central Norte Lázaro Cárdenas, No. 152, 07730 D.F., México (Mexico); Newman, R.C. [University of Toronto, Department of Chemical Engineering and Applied Chemistry, 200 College Street, Toronto M5S 3E5 (Canada)

2013-12-15

The secondary phase transformations in a commercial super duplex stainless steel were investigated by micro-chemical analyses and high resolution scanning probe microscopy. Energy dispersive X-ray and electron probe detected ferrite and austenite as well as secondary phases in unetched aged duplex stainless steel type 25Cr-7Ni-3Mo. Volta potential indicated that nitride and sigma appeared more active than ferrite, while secondary austenite and austenite presented a nobler potential. Reversal order in nobility is thought to be attributable to the potential ranking provided by oxide nature diversity as a result of secondary phase surface compositions on steel. After eutectoid transformation, secondary austenite was detected by electron probe microanalysis, whereas atomic force microscopy distinguished this phase from former austenite by image contrast. Magnetic force microscopy revealed a “ghosted” effect on the latter microstructure probably derived from metal memory reminiscence of mechanical polishing at passivity and long range magnetic forces of ferrite phase. - Highlights: • Nobility detection of secondary phases by SKPFM in DSS particles is not a straightforward procedure. • As Volta potential and contrast are not always consistent SKPFM surface oxides is thought played an important role in detection. • AFM distinguished secondary austenite from former austenite by image contrast though SEM required EPMA.

Experimental determination of conduction and valence bands of semiconductor nanoparticles using Kelvin probe force microscopy

International Nuclear Information System (INIS)

Zhang Wen; Chen Yongsheng

2013-01-01

The ability to determine a semiconductor’s band edge positions is important for the design of new photocatalyst materials. In this paper, we introduced an experimental method based on Kelvin probe force microscopy to determine the conduction and valence band edge energies of semiconductor nanomaterials, which has rarely been demonstrated. We tested the method on six semiconductor nanoparticles (α-Fe 2 O 3 , CeO 2 , Al 2 O 3 , CuO, TiO 2 , and ZnO) with known electronic structures. The experimentally determined band edge positions for α-Fe 2 O 3 , Al 2 O 3 , and CuO well matched the literature values with no statistical difference. Except CeO 2 , all other metal oxides had a consistent upward bias in the experimental measurements of band edge positions because of the shielding effect of the adsorbed surface water layer. This experimental approach may outstand as a unique alternative way of probing the band edge energy positions of semiconductor materials to complement the current computational methods, which often find limitations in new synthetic or complex materials. Ultimately, this work provides scientific foundation for developing experimental tools to probe nanoscale electronic properties of photocatalytic materials, which will drive breakthroughs in the design of novel photocatalytic systems and advance the fundamental understanding of material properties.

Investigation of the surface potential of TiO2 (110) by frequency-modulation Kelvin probe force microscopy

Science.gov (United States)

Kou, Lili; Li, Yan Jun; Kamijyo, Takeshi; Naitoh, Yoshitaka; Sugawara, Yasuhiro

2016-12-01

We investigate the surface potential distribution on a TiO2 (110)-1 × 1 surface by Kelvin probe force microscopy (KPFM) and atom-dependent bias-distance spectroscopic mapping. The experimental results demonstrate that the local contact potential difference increases on twofold-coordinated oxygen sites, and decreases on OH defects and fivefold-coordinated Ti sites. We propose a qualitative model to explain the origin of the surface potential of TiO2 (110). We qualitatively calculate the surface potential induced by chemical potential and permanent surface dipole. The calculated results agree with our experimental ones. Therefore, we suggest that the surface potential of TiO2 (110) is dominated not only by the permanent surface dipole between the tip apex atom and surface, but also by the dipoles induced by the chemical interaction between the tip and sample. The KPFM technique demonstrate the possibility of investigation of the charge transfer phenomenon on TiO2 surface under gas conditions. It is useful for the elucidation of the mechanism of the catalytic reactions.

Effect of dopant density on contact potential difference across n-type GaAs homojunctions using Kelvin Probe Force Microscopy

Science.gov (United States)

Boumenou, C. Kameni; Urgessa, Z. N.; Djiokap, S. R. Tankio; Botha, J. R.; Nel, J.

2018-04-01

In this study, cross-sectional surface potential imaging of n+/semi-insulating GaAs junctions is investigated by using amplitude mode kelvin probe force microscopy. The measurements have shown two different potential profiles, related to the difference in surface potential between the semi-insulating (SI) substrate and the epilayers. It is shown that the contact potential difference (CPD) between the tip and the sample is higher on the semi-insulating substrate side than on the n-type epilayer side. This change in CPD across the interface has been explained by means of energy band diagrams indicating the relative Fermi level positions. In addition, it has also been found that the CPD values across the interface are much smaller than the calculated values (on average about 25% of the theoretical values) and increase with the electron density. Therefore, the results presented in study are only in qualitative agreement with the theory.

Electrical characterization of grain boundaries of CZTS thin films using conductive atomic force microscopy techniques

Energy Technology Data Exchange (ETDEWEB)

Muhunthan, N.; Singh, Om Pal [Compound Semiconductor Solar Cell, Physics of Energy Harvesting Division, New Delhi 110012 (India); Toutam, Vijaykumar, E-mail: toutamvk@nplindia.org [Quantum Phenomena and Applications Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Singh, V.N., E-mail: singhvn@nplindia.org [Compound Semiconductor Solar Cell, Physics of Energy Harvesting Division, New Delhi 110012 (India)

2015-10-15

Graphical abstract: Experimental setup for conducting AFM (C-AFM). - Highlights: • Cu{sub 2}ZnSnS{sub 4} (CZTS) thin film was grown by reactive co-sputtering. • The electronic properties were probed using conducting atomic force microscope, scanning Kelvin probe microscopy and scanning capacitance microscopy. • C-AFM current flow mainly through grain boundaries rather than grain interiors. • SKPM indicated higher potential along the GBs compared to grain interiors. • The SCM explains that charge separation takes place at the interface of grain and grain boundary. - Abstract: Electrical characterization of grain boundaries (GB) of Cu-deficient CZTS (Copper Zinc Tin Sulfide) thin films was done using atomic force microscopic (AFM) techniques like Conductive atomic force microscopy (CAFM), Kelvin probe force microscopy (KPFM) and scanning capacitance microscopy (SCM). Absorbance spectroscopy was done for optical band gap calculations and Raman, XRD and EDS for structural and compositional characterization. Hall measurements were done for estimation of carrier mobility. CAFM and KPFM measurements showed that the currents flow mainly through grain boundaries (GB) rather than grain interiors. SCM results showed that charge separation mainly occurs at the interface of grain and grain boundaries and not all along the grain boundaries.

Measuring minority-carrier diffusion length using a Kelvin probe force microscope

International Nuclear Information System (INIS)

Shikler, R.; Fried, N.; Meoded, T.; Rosenwaks, Y.

2000-01-01

A method based on Kelvin probe force microscopy for measuring minority-carrier diffusion length in semiconductors is described. The method is based on measuring the surface photovoltage between the tip of an atomic force microscope and the surface of an illuminated semiconductor junction. The photogenerated carriers diffuse to the junction and change the contact potential difference between the tip and the sample, as a function of the distance from the junction. The diffusion length L is then obtained by fitting the measured contact potential difference using the minority-carrier continuity equation. The method was applied to measurements of electron diffusion length in GaP pn and Schottky junctions. The measured diffusion length was found to be ∼2 μm, in good agreement with electron beam induced current measurements

Enhancing dynamic scanning force microscopy in air: as close as possible

International Nuclear Information System (INIS)

Palacios-Lidon, E; Perez-Garcia, B; Colchero, J

2009-01-01

Frequency modulation dynamic scanning force microscopy has been implemented in ambient conditions using low oscillation amplitudes (<1 nm) to simultaneously record not only topographic but also additional channels of information, in particular contact potential images. The performance of this mode as compared to the conventional amplitude modulation mode is analyzed in detail using a biological molecule, turning yellow mosaic virus RNA, as the model sample. On the basis of scanning force microscopy imaging as well as spectroscopy experiments, we find that for such very small samples the frequency modulation mode is superior since it can be operated with smaller tip-sample interaction, smaller effective tip-sample distance and lower forces. Combined with Kelvin probe microscopy it results not only in considerably higher electrostatic resolution, but also in correct quantitative values for the contact potential as compared to traditional amplitude modulation scanning force microscopy.

Surface potential measurement on contact resistance of amorphous-InGaZnO thin film transistors by Kelvin probe force microscopy

Science.gov (United States)

Han, Zhiheng; Xu, Guangwei; Wang, Wei; Lu, Congyan; Lu, Nianduan; Ji, Zhuoyu; Li, Ling; Liu, Ming

2016-07-01

Contact resistance plays an important role in amorphous InGaZnO (a-IGZO) thin film transistors (TFTs). In this paper, the surface potential distributions along the channel have been measured by using Kelvin probe force microscopy (KPFM) on operating a-IGZO TFTs, and sharp potential drops at the edges of source and drain were observed. The source and drain contact resistances can be extracted by dividing sharp potential drops with the corresponding drain to source current. It is found that the contact resistances could not be neglected compared with the whole channel resistances in the a-IGZO TFT, and the contact resistances decrease remarkably with increasing gate biased voltage. Our results suggest that the contact resistances can be controlled by tuning the gate biased voltage. Moreover, a transition from gradual channel approximation to space charge region was observed through the surface potential map directly when TFT operating from linear regime to saturation regime.

Observations of Convectively Coupled Kelvin Waves forced by Extratropical Wave Activity

Science.gov (United States)

Kiladis, G. N.; Biello, J. A.; Straub, K. H.

2012-12-01

It is well established by observations that deep tropical convection can in certain situations be forced by extratropical Rossby wave activity. Such interactions are a well-known feature of regions of upper level westerly flow, and in particular where westerlies and equatorward wave guiding by the basic state occur at low enough latitudes to interact with tropical and subtropical moisture sources. In these regions convection is commonly initiated ahead of upper level troughs, characteristic of forcing by quasi-geostrophic dynamics. However, recent observational evidence indicates that extratropical wave activity is also associated with equatorial convection even in regions where there is a "critical line" to Rossby wave propagation at upper levels, that is, where the zonal phase speed of the wave is equal to the zonal flow speed. A common manifestation of this type of interaction involves the initiation of convectively coupled Kelvin waves, as well as mixed Rossby-gravity (MRG) waves. These waves are responsible for a large portion of the convective variability within the ITCZ over the Indian, Pacific, and Atlantic sectors, as well as within the Amazon Basin of South America. For example, Kelvin waves originating within the western Pacific ITCZ are often triggered by Rossby wave activity propagating into the Australasian region from the South Indian Ocean extratropics. At other times, Kelvin waves are seen to originate along the eastern slope of the Andes. In the latter case the initial forcing is sometimes linked to a low-level "pressure surge," initiated by wave activity propagating equatorward from the South Pacific storm track. In yet other cases, such as over Africa, the forcing appears to be related to wave activity in the extratropics which is not necessarily propagating into low latitudes, but appears to "project" onto the Kelvin structure, in line with past theoretical and modeling studies. Observational evidence for extratropical forcing of Kelvin and MRG

Comparative study of donor-induced quantum dots in Si nano-channels by single-electron transport characterization and Kelvin probe force microscopy

International Nuclear Information System (INIS)

Tyszka, K.; Moraru, D.; Samanta, A.; Mizuno, T.; Tabe, M.; Jabłoński, R.

2015-01-01

We comparatively study donor-induced quantum dots in Si nanoscale-channel transistors for a wide range of doping concentration by analysis of single-electron tunneling transport and surface potential measured by Kelvin probe force microscopy (KPFM). By correlating KPFM observations of donor-induced potential landscapes with simulations based on Thomas-Fermi approximation, it is demonstrated that single-electron tunneling transport at lowest gate voltages (for smallest coverage of screening electrons) is governed most frequently by only one dominant quantum dot, regardless of doping concentration. Doping concentration, however, primarily affects the internal structure of the quantum dot. At low concentrations, individual donors form most of the quantum dots, i.e., “donor-atom” quantum dots. In contrast, at high concentrations above metal-insulator transition, closely placed donors instead of individual donors form more complex quantum dots, i.e., “donor-cluster” quantum dots. The potential depth of these “donor-cluster” quantum dots is significantly reduced by increasing gate voltage (increasing coverage of screening electrons), leading to the occurrence of multiple competing quantum dots

Scanning Kelvin probe force microscopy as a means of predicting the electrochemical characteristics of the surface of a modified AA4xxx/AA3xxx (Al alloys) brazing sheet

International Nuclear Information System (INIS)

Afshar, F. Norouzi; Wit, J.H.W. de; Terryn, H.; Mol, J.M.C.

2013-01-01

Highlights: ► Macro- and micro-electrochemical surface properties of an aluminium brazing sheet were investigated. ► Electrochemical surface properties before and after brazing were studied and compared. ► Scanning Kelvin probe force microscopy and potentiodynamic polarization measurements were performed. ► The electrochemical responses were correlated to the pre- and post-brazing treatment microstructure. -- Abstract: Macro- and micro-electrochemical properties of clad and core surfaces of a modified AA4xxx/AA3xxx brazing sheet material, before and after brazing, have been evaluated and compared. By scanning Kelvin probe force microscopy (SKPFM), the Volta potential distribution over the brazed and non-brazed clad surfaces was measured. The changes in the Volta potential maps were correlated to the macro-electrochemical responses of the surfaces and the microstructural features that evolve as a result of brazing. By performing potentiodynamic polarization experiments and microscopic analysis of the corroded surfaces and cross sections, the suitability of SKPFM analysis for corrosion performance prediction of the aluminium brazing sheet material in a sea water acidified accelerated test (SWAAT) environment was confirmed. Considering the purity of Si phase in the structures of both brazed and non-brazed material, it is suggested that Si can be applied as a reliable local reference in both structures to compare the changes in Volta potential differences as the result of different heat treatments of aluminium brazing sheet. Increasing the copper content of the re-solidified clad material as a result of brazing treatment was found to increase the Volta potential of the matrix which in turn reduces the cathodic protection power of the re-solidified clad material towards the core material

Detection of charge storage on molecular thin films of tris(8-hydroxyquinoline) aluminum (Alq3) by Kelvin force microscopy: a candidate system for high storage capacity memory cells.

Science.gov (United States)

Paydavosi, Sarah; Aidala, Katherine E; Brown, Patrick R; Hashemi, Pouya; Supran, Geoffrey J; Osedach, Timothy P; Hoyt, Judy L; Bulović, Vladimir

2012-03-14

Retention and diffusion of charge in tris(8-hydroxyquinoline) aluminum (Alq(3)) molecular thin films are investigated by injecting electrons and holes via a biased conductive atomic force microscopy tip into the Alq(3) films. After the charge injection, Kelvin force microscopy measurements reveal minimal changes with time in the spatial extent of the trapped charge domains within Alq(3) films, even for high hole and electron densities of >10(12) cm(-2). We show that this finding is consistent with the very low mobility of charge carriers in Alq(3) thin films (<10(-7) cm(2)/(Vs)) and that it can benefit from the use of Alq(3) films as nanosegmented floating gates in flash memory cells. Memory capacitors using Alq(3) molecules as the floating gate are fabricated and measured, showing durability over more than 10(4) program/erase cycles and the hysteresis window of up to 7.8 V, corresponding to stored charge densities as high as 5.4 × 10(13) cm(-2). These results demonstrate the potential for use of molecular films in high storage capacity nonvolatile memory cells. © 2012 American Chemical Society

Multimodal Kelvin Probe Force Microscopy Investigations of a Photovoltaic WSe2/MoS2 Type-II Interface.

Science.gov (United States)

Almadori, Yann; Bendiab, Nedjma; Grévin, Benjamin

2018-01-10

Atomically thin transition-metal dichalcogenides (TMDC) have become a new platform for the development of next-generation optoelectronic and light-harvesting devices. Here, we report a Kelvin probe force microscopy (KPFM) investigation carried out on a type-II photovoltaic heterojunction based on WSe 2 monolayer flakes and a bilayer MoS 2 film stacked in vertical configuration on a Si/SiO 2 substrate. Band offset characterized by a significant interfacial dipole is pointed out at the WSe 2 /MoS 2 vertical junction. The photocarrier generation process and phototransport are studied by applying a differential technique allowing to map directly two-dimensional images of the surface photovoltage (SPV) over the vertical heterojunctions (vHJ) and in its immediate vicinity. Differential SPV reveals the impact of chemical defects on the photocarrier generation and that negative charges diffuse in the MoS 2 a few hundreds of nanometers away from the vHJ. The analysis of the SPV data confirms unambiguously that light absorption results in the generation of free charge carriers that do not remain coulomb-bound at the type-II interface. A truly quantitative determination of the electron-hole (e-h) quasi-Fermi levels splitting (i.e., the open-circuit voltage) is achieved by measuring the differential vacuum-level shift over the WSe 2 flakes and the MoS 2 layer. The dependence of the energy-level splitting as a function of the optical power reveals that Shockley-Read-Hall processes significantly contribute to the interlayer recombination dynamics. Finally, a newly developed time-resolved mode of the KPFM is applied to map the SPV decay time constants. The time-resolved SPV images reveal the dynamics of delayed recombination processes originating from photocarriers trapping at the SiO 2 /TMDC interfaces.

The kelvin redefined

Science.gov (United States)

Machin, Graham

2018-02-01

On 20 May 2019 it is anticipated that the most radical revision of the International System of Units (the SI), since its inception, will come into force. From that point, all the SI units will be based on defined values of fundamental constants of nature. In this paper the redefinition of the kelvin and its implications are considered. The topic will be introduced by discussing how the wording of the new definition of the kelvin developed. The kelvin redefinition is reliant on a secure low-uncertainty value of the Boltzmann constant; its determination by different physical methods and how the final definitive value for the kelvin redefinition was arrived at is discussed. The redefined kelvin will be implemented through a document known as the mise en pratique (i.e. the ‘practical realisation’) for the definition of the kelvin (MeP-K). The development and contents of the MeP-K will be described. There follows a discussion of contemporary primary thermometry, which is the bedrock on which a secure kelvin redefinition will be founded. Finally the paper ends with a discussion of the implications of the redefinition, for traceability, and, more widely, the practice of thermometry in general.

Numerical study of the lateral resolution in electrostatic force microscopy for dielectric samples

International Nuclear Information System (INIS)

Riedel, C; AlegrIa, A; Colmenero, J; Schwartz, G A; Saenz, J J

2011-01-01

We present a study of the lateral resolution in electrostatic force microscopy for dielectric samples in both force and gradient modes. Whereas previous studies have reported expressions for metallic surfaces having potential heterogeneities (Kelvin probe force microscopy), in this work we take into account the presence of a dielectric medium. We introduce a definition of the lateral resolution based on the force due to a test particle being either a point charge or a polarizable particle on the dielectric surface. The behaviour has been studied over a wide range of typical experimental parameters: tip-sample distance (1-20) nm, sample thickness (0-5) μm and dielectric constant (1-20), using the numerical simulation of the equivalent charge method. For potential heterogeneities on metallic surfaces expressions are in agreement with the bibliography. The lateral resolution of samples having a dielectric constant of more than 10 tends to metallic behaviour. We found a characteristic thickness of 100 nm, above which the lateral resolution measured on the dielectric surface is close to that of an infinite medium. As previously reported, the lateral resolution is better in the gradient mode than in the force mode. Finally, we showed that for the same experimental conditions, the lateral resolution is better for a polarizable particle than for a charge, i.e. dielectric heterogeneities should always look 'sharper' (better resolved) than inhomogeneous charge distributions. This fact should be taken into account when interpreting images of heterogeneous samples.

Numerical study of the lateral resolution in electrostatic force microscopy for dielectric samples

Energy Technology Data Exchange (ETDEWEB)

Riedel, C; AlegrIa, A; Colmenero, J [Departamento de Fisica de Materiales UPV/EHU, Facultad de Quimica, Apartado 1072, 20080 San Sebastian (Spain); Schwartz, G A [Centro de Fisica de Materiales CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, 20018 San Sebastian (Spain); Saenz, J J, E-mail: riedel@ies.univ-montp2.fr [Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastian (Spain)

2011-07-15

We present a study of the lateral resolution in electrostatic force microscopy for dielectric samples in both force and gradient modes. Whereas previous studies have reported expressions for metallic surfaces having potential heterogeneities (Kelvin probe force microscopy), in this work we take into account the presence of a dielectric medium. We introduce a definition of the lateral resolution based on the force due to a test particle being either a point charge or a polarizable particle on the dielectric surface. The behaviour has been studied over a wide range of typical experimental parameters: tip-sample distance (1-20) nm, sample thickness (0-5) {mu}m and dielectric constant (1-20), using the numerical simulation of the equivalent charge method. For potential heterogeneities on metallic surfaces expressions are in agreement with the bibliography. The lateral resolution of samples having a dielectric constant of more than 10 tends to metallic behaviour. We found a characteristic thickness of 100 nm, above which the lateral resolution measured on the dielectric surface is close to that of an infinite medium. As previously reported, the lateral resolution is better in the gradient mode than in the force mode. Finally, we showed that for the same experimental conditions, the lateral resolution is better for a polarizable particle than for a charge, i.e. dielectric heterogeneities should always look 'sharper' (better resolved) than inhomogeneous charge distributions. This fact should be taken into account when interpreting images of heterogeneous samples.

Observations of Confinement of a Paramagnetic Liquid in Model Propellant Tanks in Microgravity by the Kelvin Force

Science.gov (United States)

Kuhlman, John; Gray, Donald D.; Barnard, Austin; Hazelton, Jennifer; Lechliter, Matthew; Starn, Andrew; Battleson, Charles; Glaspell, Shannon; Kreitzer, Paul; Leichliter, Michelle

2002-11-01

The magnetic Kelvin force has been proposed as an artificial gravity to control the orientation of paramagnetic liquid propellants such as liquid oxygen in a microgravity environment. This paper reports experiments performed in the NASA "Weightless Wonder" KC-135 aircraft, through the Reduced Gravity Student Flight Opportunities Program. The aircraft flies through a series of parabolic arcs providing about 25 s of microgravity in each arc. The experiment was conceived, designed, constructed, and performed by the undergraduate student team and their two faculty advisors. Two types of tanks were tested: square-base prismatic tanks 5 cm x 5 cm x 8.6 cm and circular cylinders 5 cm in diameter and 8.6 cm tall. The paramagnetic liquid was a 3.3 molar solution of MnCl2 in water. Tests were performed with each type of tank filled to depths of 1 cm and 4 cm. Each test compared a pair of tanks that were identical except that the base of one was a pole face of a 0.6 Tesla permanent magnet. The Kelvin force attracts paramagnetic materials toward regions of higher magnetic field. It was hypothesized that the Kelvin force would hold the liquid in the bottom of the tanks during the periods of microgravity. The tanks were installed in a housing that could slide on rails transverse to the flight direction. By manually shoving the housing, an identical impulse could be provided to each tank at the beginning of each period of microgravity. The resulting fluid motions were videotaped for later analysis.

Study of Perylenetetracarboxylic Acid Dimethylimide Films by Cyclic Thermal Desorption and Scanning Probe Microscopy

Science.gov (United States)

Pochtennyi, A. E.; Lappo, A. N.; Il'yushonok, I. P.

2018-02-01

Some results of studying the direct-current (DC) conductivity of perylenetetracarboxylic acid dimethylimide films by cyclic oxygen thermal desorption are presented. The microscopic parameters of hopping electron transport over localized impurity and intrinsic states were determined. The bandgap width and the sign of major current carriers were determined by scanning probe microscopy methods (atomic force microscopy, scanning probe spectroscopy, and photoassisted Kelvin probe force microscopy). The possibility of the application of photoassisted scanning tunneling microscopy for the nanoscale phase analysis of photoconductive films is discussed.

Photo-assisted Kelvin probe force microscopy investigation of three dimensional GaN structures with various crystal facets, doping types, and wavelengths of illumination

Science.gov (United States)

Ali Deeb, Manal; Ledig, Johannes; Wei, Jiandong; Wang, Xue; Wehmann, Hergo-Heinrich; Waag, Andreas

2017-08-01

Three dimensional GaN structures with different crystal facets and doping types have been investigated employing the surface photo-voltage (SPV) method to monitor illumination-induced surface charge behavior using Kelvin probe force microscopy. Various photon energies near and below the GaN bandgap were used to modify the generation of electron-hole pairs and their motion under the influence of the electric field near the GaN surface. Fast and slow processes for Ga-polar c-planes on both Si-doped n-type as well as Mg-doped p-type GaN truncated pyramid micro-structures were found and their origin is discussed. The immediate positive (for n-type) and negative (for p-type) SPV response dominates at band-to-band and near-bandgap excitation, while only the slow process is present at sub-bandgap excitation. The SPV behavior for the semi-polar facets of the p-type GaN truncated pyramids has a similar characteristic to that on its c-plane, which indicates that it has a comparable band bending and no strong influence of the polarity-induced charges is detectable. The SPV behavior of the non-polar m-facets of the Si-doped n-type part of a transferred GaN column is similar to that of a clean c-plane GaN surface during illumination. However, the SPV is smaller in magnitude, which is attributed to intrinsic surface states of m-plane surfaces and their influence on the band bending. The SPV behavior of the non-polar m-facet of the slightly Mg-doped part of this GaN column is found to behave differently. Compared to c- and r-facets of p-type surfaces of GaN-light-emitting diode micro-structures, the m-plane is more chemically stable.

Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques.

Science.gov (United States)

Bolker, Asaf; Saguy, Cecile; Kalish, Rafi

2014-09-26

The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND's size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques.

Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques

Science.gov (United States)

Bolker, Asaf; Saguy, Cecile; Kalish, Rafi

2014-09-01

The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND’s size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques.

Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques

International Nuclear Information System (INIS)

Bolker, Asaf; Kalish, Rafi; Saguy, Cecile

2014-01-01

The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND’s size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques. (paper)

Magnetoelectric force microscopy based on magnetic force microscopy with modulated electric field.

Science.gov (United States)

Geng, Yanan; Wu, Weida

2014-05-01

We present the realization of a mesoscopic imaging technique, namely, the Magnetoelectric Force Microscopy (MeFM), for visualization of local magnetoelectric effect. The basic principle of MeFM is the lock-in detection of local magnetoelectric response, i.e., the electric field-induced magnetization, using magnetic force microscopy. We demonstrate MeFM capability by visualizing magnetoelectric domains on single crystals of multiferroic hexagonal manganites. Results of several control experiments exclude artifacts or extrinsic origins of the MeFM signal. The parameters are tuned to optimize the signal to noise ratio.

Scanning-probe-microscopy of polyethylene terephthalate surface treatment by argon ion beam

Energy Technology Data Exchange (ETDEWEB)

Espinoza-Beltran, Francisco [Polymer & Biopolymer Group, Libramiento Norponiente no. 2000, Cinvestav Queretaro, Queretaro 76230 (Mexico); Sanchez, Isaac C. [Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); España-Sánchez, Beatriz L.; Mota-Morales, Josué D.; Carrillo, Salvador; Enríquez-Flores, C.I. [Polymer & Biopolymer Group, Libramiento Norponiente no. 2000, Cinvestav Queretaro, Queretaro 76230 (Mexico); Poncin-Epaillard, Fabienne, E-mail: epaill@univ-lemans.fr [Institute for Molecules and Materials, UMR CNRS 6283, Av. O. Messiaen, Universitè du Maine, Le Mans 72085 (France); Luna-Barcenas, Gabriel, E-mail: gluna@qro.cinvestav.mx [Polymer & Biopolymer Group, Libramiento Norponiente no. 2000, Cinvestav Queretaro, Queretaro 76230 (Mexico)

2015-11-01

Highlights: • Kelvin-probe-force microscopy helps study of PET surface treated by Ar ion beam. • Ar ion beam surface treatment promotes chain scission and N insertion. • Surface roughness and work function increases as intensity of ion energy increases. • Adhesive force of PET decrease due to the surface changes by ion bombardment. - Abstract: The effect of argon (Ar{sup +}) ion beam treatment on the surface of polyethylene terephthalate (PET) samples was studied by scanning probe microscopy (SPM) and the changes in surface topography were assessed by atomic force microscopy (AFM). Kelvin probe force microscopy (KPFM) sheds light of adhesion force between treated polymer films and a Pt/Cr probe under dry conditions, obtaining the contact potential difference of material. As a result of Ar{sup +} ion bombardment, important surface chemical changes were detected by X-ray photoelectron spectroscopy (XPS) measurements such as chains scission and incorporation of nitrogen species. Ion beam treatment increases the surface roughness from 0.49 ± 0.1 nm to 7.2 ± 0.1 nm and modify the surface potential of PET samples, decreasing the adhesive forces from 12.041 ± 2.1 nN to 5.782 ± 0.06 nN, and producing a slight increase in the electronic work function (Φ{sub e}) from 5.1 V (untreated) to 5.2 V (treated). Ar{sup +} ion beam treatment allows to potentially changing the surface properties of PET, modifying surface adhesion, improving surface chemical changes, wetting properties and surface potential of polymers.

Interfacial force measurements using atomic force microscopy

NARCIS (Netherlands)

Chu, L.

2018-01-01

Atomic Force Microscopy (AFM) can not only image the topography of surfaces at atomic resolution, but can also measure accurately the different interaction forces, like repulsive, adhesive and lateral existing between an AFM tip and the sample surface. Based on AFM, various extended techniques have

Force modulation for improved conductive-mode atomic force microscopy

NARCIS (Netherlands)

Koelmans, W.W.; Sebastian, Abu; Despont, Michel; Pozidis, Haris

We present an improved conductive-mode atomic force microscopy (C-AFM) method by modulating the applied loading force on the tip. Unreliable electrical contact and tip wear are the primary challenges for electrical characterization at the nanometer scale. The experiments show that force modulation

Minimizing tip-sample forces in jumping mode atomic force microscopy in liquid

Energy Technology Data Exchange (ETDEWEB)

Ortega-Esteban, A. [Departamento de Fisica de la Materia Condensada, C-3, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Horcas, I. [Nanotec Electronica S.L., Centro Empresarial Euronova 3, Ronda de Poniente 12, 28760 Tres Cantos, Madrid (Spain); Hernando-Perez, M. [Departamento de Fisica de la Materia Condensada, C-3, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Ares, P. [Nanotec Electronica S.L., Centro Empresarial Euronova 3, Ronda de Poniente 12, 28760 Tres Cantos, Madrid (Spain); Perez-Berna, A.J.; San Martin, C.; Carrascosa, J.L. [Centro Nacional de Biotecnologia (CNB-CSIC), Darwin 3, 28049 Madrid (Spain); Pablo, P.J. de [Departamento de Fisica de la Materia Condensada, C-3, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Gomez-Herrero, J., E-mail: julio.gomez@uam.es [Departamento de Fisica de la Materia Condensada, C-3, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

2012-03-15

Control and minimization of tip-sample interaction forces are imperative tasks to maximize the performance of atomic force microscopy. In particular, when imaging soft biological matter in liquids, the cantilever dragging force prevents identification of the tip-sample mechanical contact, resulting in deleterious interaction with the specimen. In this work we present an improved jumping mode procedure that allows detecting the tip-sample contact with high accuracy, thus minimizing the scanning forces ({approx}100 pN) during the approach cycles. To illustrate this method we report images of human adenovirus and T7 bacteriophage particles which are prone to uncontrolled modifications when using conventional jumping mode. -- Highlights: Black-Right-Pointing-Pointer Improvement in atomic force microscopy in buffer solution. Black-Right-Pointing-Pointer Peak force detection. Black-Right-Pointing-Pointer Subtracting the cantilever dragging force. Black-Right-Pointing-Pointer Forces in the 100 pN range. Black-Right-Pointing-Pointer Imaging of delicate viruses with atomic force microscopy.

Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

Directory of Open Access Journals (Sweden)

Thomas König

2011-01-01

Full Text Available 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.

Application of scanning Kelvin probe microscopy for the electrical characterization of microcrystalline silicon for photovoltaics

International Nuclear Information System (INIS)

Breymesser, A.

2000-05-01

In the last years microcrystalline silicon thin films have attracted great attention as a new photovoltaic material. With this material it is possible to combine simple and cheap low temperature deposition techniques known from amorphous silicon with the long-term stability of the photovoltaic performance like in bulk crystalline silicon solar cells. The critical point is the deposition procedure with numerous tunable parameters influencing the quality and character of the produced diode structures. Additionally there is a great uncertainty about unintentionally incorporated defects, which is not affected by the deposition parameters. Extended investigation of the material, diode and solar cell characteristics is essential in order to correlate the impact of deposition conditions with the quality of the devices. The situation is complicated due to the anisotropic and inhomogeneous character of microcrystalline silicon. Scanning Kelvin probe microscopy (SKPM) is a work function measurement method based on a scanning force microscope (SFM) and a modified Kelvin probe technique. Due to the excellent lateral resolution of the SFM work function measurements with resolutions far below the micrometer level can be carried out. Applied on doped microcrystalline silicon structures it is possible to visualize the position of the Fermi level within the band gap and the influence of the deposition conditions on it. Within this work a SKPM based on a commercially available SFM was constructed and built. Great effort was concentrated on the characterization of the SKPM experiment. On the basis of an extended knowledge about the performance investigations concentrated on cross sections of microcrystalline silicon diode structures produced by hot-wire chemical vapor deposition (HW-CVD). A pin structure for the diodes was chosen due to the low diffusion lengths within this rather defective material. The evolution of the built-in electric drift field within the intrinsic absorber is

Magnetic force microscopy : Quantitative issues in biomaterials

NARCIS (Netherlands)

Passeri, D.; Dong, C.; Reggente, M.; Angeloni, L.; Barteri, M.; Scaramuzzo, F.A.; De Angelis, F.; Marinelli, F.; Antonelli, F.; Rinaldi, F.; Marianecci, C.; Carafa, M.; Sorbo, A.; Sordi, D.; Arends, I.W.C.E.; Rossi, M.

2014-01-01

Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples

Kelvin probe microscopy and electronic transport measurements in reduced graphene oxide chemical sensors

Science.gov (United States)

Kehayias, Christopher E.; MacNaughton, Samuel; Sonkusale, Sameer; Staii, Cristian

2013-06-01

Reduced graphene oxide (RGO) is an electronically hybrid material that displays remarkable chemical sensing properties. Here, we present a quantitative analysis of the chemical gating effects in RGO-based chemical sensors. The gas sensing devices are patterned in a field-effect transistor geometry, by dielectrophoretic assembly of RGO platelets between gold electrodes deposited on SiO2/Si substrates. We show that these sensors display highly selective and reversible responses to the measured analytes, as well as fast response and recovery times (tens of seconds). We use combined electronic transport/Kelvin probe microscopy measurements to quantify the amount of charge transferred to RGO due to chemical doping when the device is exposed to electron-acceptor (acetone) and electron-donor (ammonia) analytes. We demonstrate that this method allows us to obtain high-resolution maps of the surface potential and local charge distribution both before and after chemical doping, to identify local gate-susceptible areas on the RGO surface, and to directly extract the contact resistance between the RGO and the metallic electrodes. The method presented is general, suggesting that these results have important implications for building graphene and other nanomaterial-based chemical sensors.

Kelvin probe microscopy and electronic transport measurements in reduced graphene oxide chemical sensors.

Science.gov (United States)

Kehayias, Christopher E; MacNaughton, Samuel; Sonkusale, Sameer; Staii, Cristian

2013-06-21

Reduced graphene oxide (RGO) is an electronically hybrid material that displays remarkable chemical sensing properties. Here, we present a quantitative analysis of the chemical gating effects in RGO-based chemical sensors. The gas sensing devices are patterned in a field-effect transistor geometry, by dielectrophoretic assembly of RGO platelets between gold electrodes deposited on SiO2/Si substrates. We show that these sensors display highly selective and reversible responses to the measured analytes, as well as fast response and recovery times (tens of seconds). We use combined electronic transport/Kelvin probe microscopy measurements to quantify the amount of charge transferred to RGO due to chemical doping when the device is exposed to electron-acceptor (acetone) and electron-donor (ammonia) analytes. We demonstrate that this method allows us to obtain high-resolution maps of the surface potential and local charge distribution both before and after chemical doping, to identify local gate-susceptible areas on the RGO surface, and to directly extract the contact resistance between the RGO and the metallic electrodes. The method presented is general, suggesting that these results have important implications for building graphene and other nanomaterial-based chemical sensors.

Electrochemical force microscopy

Energy Technology Data Exchange (ETDEWEB)

Kalinin, Sergei V.; Jesse, Stephen; Collins, Liam F.; Rodriguez, Brian J.

2017-01-10

A system and method for electrochemical force microscopy are provided. The system and method are based on a multidimensional detection scheme that is sensitive to forces experienced by a biased electrode in a solution. The multidimensional approach allows separation of fast processes, such as double layer charging, and charge relaxation, and slow processes, such as diffusion and faradaic reactions, as well as capturing the bias dependence of the response. The time-resolved and bias measurements can also allow probing both linear (small bias range) and non-linear (large bias range) electrochemical regimes and potentially the de-convolution of charge dynamics and diffusion processes from steric effects and electrochemical reactivity.

Magnetic Resonance Force Microscopy System

Data.gov (United States)

Federal Laboratory Consortium — The Magnetic Resonance Force Microscopy (MRFM) system, developed by ARL, is the world's most sensitive nuclear magnetic resonance (NMR) spectroscopic analysis tool,...

Thermally oxidized Inconel 600 and 690 nickel-based alloys characterizations by combination of global photoelectrochemistry and local near-field microscopy techniques (STM, STS, AFM, SKPFM)

Science.gov (United States)

Mechehoud, F.; Benaioun, N. E.; Hakiki, N. E.; Khelil, A.; Simon, L.; Bubendorff, J. L.

2018-03-01

Thermally oxidized nickel-based alloys are studied by scanning tunnelling microscopy (STM), scanning tunnelling spectroscopy (STS), atomic force microscopy (AFM), scanning kelvin probe force microscopy (SKPFM) and photoelectro-chemical techniques as a function of oxidation time at a fixed temperature of 623 K. By photoelectrochemistry measurements we identify the formation of three oxides NiO, Fe2O3, Cr2O3 and determine the corresponding gap values. We use these values as parameter for imaging the surface at high bias voltage by STM allowing the spatial localization and identification of both NiO, Fe2O3 oxide phases using STS measurements. Associated to Kelvin probe measurements we show also that STS allow to distinguished NiO from Cr2O3 and confirm that the Cr2O3 is not visible at the surface and localized at the oxide/steel interface.

Scanning probe microscopy for the analysis of composite Ti/hydrocarbon plasma polymer thin films

Science.gov (United States)

Choukourov, A.; Grinevich, A.; Slavinska, D.; Biederman, H.; Saito, N.; Takai, O.

2008-03-01

Composite Ti/hydrocarbon plasma polymer films with different Ti concentration were deposited on silicon by dc magnetron sputtering of titanium in an atmosphere of argon and hexane. As measured by Kelvin force microscopy and visco-elastic atomic force microscopy, respectively, surface potential and hardness increase with increasing Ti content. Adhesion force to silicon and to fibrinogen molecules was stronger for the Ti-rich films as evaluated from the AFM force-distance curves. Fibrinogen forms a very soft layer on these composites with part of the protein molecules embedded in the outermost region of the plasma polymer. An increase of the surface charge due to fibrinogen adsorption has been observed and attributed to positively charged αC domains of fibrinogen molecule.

Nanoscale electrical property studies of individual GeSi quantum rings by conductive scanning probe microscopy.

Science.gov (United States)

Lv, Yi; Cui, Jian; Jiang, Zuimin M; Yang, Xinju

2012-11-29

The nanoscale electrical properties of individual self-assembled GeSi quantum rings (QRs) were studied by scanning probe microscopy-based techniques. The surface potential distributions of individual GeSi QRs are obtained by scanning Kelvin microscopy (SKM). Ring-shaped work function distributions are observed, presenting that the QRs' rim has a larger work function than the QRs' central hole. By combining the SKM results with those obtained by conductive atomic force microscopy and scanning capacitance microscopy, the correlations between the surface potential, conductance, and carrier density distributions are revealed, and a possible interpretation for the QRs' conductance distributions is suggested.

Calcite biomineralization in coccoliths: Evidence from atomic force microscopy (AFM)

DEFF Research Database (Denmark)

Henriksen, Karen; Stipp, S.L.S.

2002-01-01

geochemistry, crystal orientation, coccolith function, biomineralization, biological calcite, atomic force microscopy......geochemistry, crystal orientation, coccolith function, biomineralization, biological calcite, atomic force microscopy...

Polarization contrast in photon scanning tunnelling microscopy combined with atomic force microscopy

NARCIS (Netherlands)

Propstra, K.; Propstra, K.; van Hulst, N.F.

1995-01-01

Photon scanning tunnelling microscopy combined with atomic force microscopy allows simultaneous acquisition and direct comparison of optical and topographical images, both with a lateral resolution of about 30 nm, far beyond the optical diffraction limit. The probe consists of a modified

Fidelity imaging for atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Ghosal, Sayan, E-mail: ghos0087@umn.edu; Salapaka, Murti, E-mail: murtis@umn.edu [Nanodynamics Systems Laboratory, Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2015-01-05

Atomic force microscopy is widely employed for imaging material at the nanoscale. However, real-time measures on image reliability are lacking in contemporary atomic force microscopy literature. In this article, we present a real-time technique that provides an image of fidelity for a high bandwidth dynamic mode imaging scheme. The fidelity images define channels that allow the user to have additional authority over the choice of decision threshold that facilitates where the emphasis is desired, on discovering most true features on the sample with the possible detection of high number of false features, or emphasizing minimizing instances of false detections. Simulation and experimental results demonstrate the effectiveness of fidelity imaging.

Force reconstruction from tapping mode force microscopy experiments

International Nuclear Information System (INIS)

Payam, Amir F; Martin-Jimenez, Daniel; Garcia, Ricardo

2015-01-01

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. (paper)

Corrected direct force balance method for atomic force microscopy lateral force calibration

International Nuclear Information System (INIS)

Asay, David B.; Hsiao, Erik; Kim, Seong H.

2009-01-01

This paper reports corrections and improvements of the previously reported direct force balance method (DFBM) developed for lateral calibration of atomic force microscopy. The DFBM method employs the lateral force signal obtained during a force-distance measurement on a sloped surface and relates this signal to the applied load and the slope of the surface to determine the lateral calibration factor. In the original publication [Rev. Sci. Instrum. 77, 043903 (2006)], the tip-substrate contact was assumed to be pinned at the point of contact, i.e., no slip along the slope. In control experiments, the tip was found to slide along the slope during force-distance curve measurement. This paper presents the correct force balance for lateral force calibration.

Single-molecule force spectroscopy: optical tweezers, magnetic tweezers and atomic force microscopy

Science.gov (United States)

Neuman, Keir C.; Nagy, Attila

2012-01-01

Single-molecule force spectroscopy has emerged as a powerful tool to investigate the forces and motions associated with biological molecules and enzymatic activity. The most common force spectroscopy techniques are optical tweezers, magnetic tweezers and atomic force microscopy. These techniques are described and illustrated with examples highlighting current capabilities and limitations. PMID:18511917

Progress in the Correlative Atomic Force Microscopy and Optical Microscopy

Directory of Open Access Journals (Sweden)

Lulu Zhou

2017-04-01

Full Text Available Atomic force microscopy (AFM has evolved from the originally morphological imaging technique to a powerful and multifunctional technique for manipulating and detecting the interactions between molecules at nanometer resolution. However, AFM cannot provide the precise information of synchronized molecular groups and has many shortcomings in the aspects of determining the mechanism of the interactions and the elaborate structure due to the limitations of the technology, itself, such as non-specificity and low imaging speed. To overcome the technical limitations, it is necessary to combine AFM with other complementary techniques, such as fluorescence microscopy. The combination of several complementary techniques in one instrument has increasingly become a vital approach to investigate the details of the interactions among molecules and molecular dynamics. In this review, we reported the principles of AFM and optical microscopy, such as confocal microscopy and single-molecule localization microscopy, and focused on the development and use of correlative AFM and optical microscopy.

Pressure-driven ballistic Kelvin's water dropper for energy harvesting

NARCIS (Netherlands)

Xie, Yanbo; de Boer, Hans L.; van den Berg, Albert; Sprenkels, A.J.; Eijkel, Jan C.T.

2014-01-01

In this paper, we introduce a microfluidic-based self-excited energy conversion system inspired by Kelvin's water dropper but driven by inertia instead of gravity. Two micro water jets are produced by forcing water through two micropores by overpressure. The jets break up into microdroplets which

Intermittent contact atomic force microscopy in electrochemical environment

Energy Technology Data Exchange (ETDEWEB)

Haering, P; Koetz, R [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Siegenthaler, H [Bern Univ., Bern (Switzerland)

1997-06-01

In situ measurements with Atomic Force Microscopy may cause surface modifications due to the tip-surface interactions. As an alternative and less destructive method, Intermittent Contact Atomic Force Microscopy (ICAFM) has been tested in an electrolytic environment. In the ICAFM mode the tip is not constantly in contact with the surface under investigation but is tapping onto the surface with a certain frequency. A commercial Park Scientific Instruments Microscopy has been modified to enable in situ experiment with ICAFM. It was possible to image iridium oxide films with ICAFM in the electrolytic environment without any noticeable surface modifications. (author) 3 figs., 4 refs.

Contact resistance asymmetry of amorphous indium-gallium-zinc-oxide thin-film transistors by scanning Kelvin probe microscopy

Science.gov (United States)

Chen-Fei, Wu; Yun-Feng, Chen; Hai, Lu; Xiao-Ming, Huang; Fang-Fang, Ren; Dun-Jun, Chen; Rong, Zhang; You-Dou, Zheng

2016-05-01

In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain (S/D) series resistance in operating amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. The asymmetry behavior of S/D contact resistance is deduced and the underlying physics is discussed. The present results suggest that the asymmetry of S/D contact resistance is caused by the difference in bias conditions of the Schottky-like junction at the contact interface induced by the parasitic reaction between contact metal and a-IGZO. The overall contact resistance should be determined by both the bulk channel resistance of the contact region and the interface properties of the metal-semiconductor junction. Project supported by the Key Industrial R&D Program of Jiangsu Province, China (Grant No. BE2015155), the Priority Academic Program Development of Higher Education Institutions of Jiangsu Province, China, and the Fundamental Research Funds for the Central Universities, China (Grant No. 021014380033).

Atomic resolution scanning tunneling microscopy in a cryogen free dilution refrigerator at 15 mK

International Nuclear Information System (INIS)

Haan, A. M. J. den; Wijts, G. H. C. J.; Galli, F.; Oosterkamp, T. H.; Usenko, O.; Baarle, G. J. C. van; Zalm, D. J. van der

2014-01-01

Pulse tube refrigerators are becoming more common, because they are cost efficient and demand less handling than conventional (wet) refrigerators. However, a downside of a pulse tube system is the vibration level at the cold-head, which is in most designs several micrometers. We implemented vibration isolation techniques which significantly reduced vibration levels at the experiment. These optimizations were necessary for the vibration sensitive magnetic resonance force microscopy experiments at milli-kelvin temperatures for which the cryostat is intended. With these modifications we show atomic resolution scanning tunneling microscopy on graphite. This is promising for scanning probe microscopy applications at very low temperatures

Quantitative measurements of shear displacement using atomic force microscopy

International Nuclear Information System (INIS)

Wang, Wenbo; Wu, Weida; Sun, Ying; Zhao, Yonggang

2016-01-01

We report a method to quantitatively measure local shear deformation with high sensitivity using atomic force microscopy. The key point is to simultaneously detect both torsional and buckling motions of atomic force microscopy (AFM) cantilevers induced by the lateral piezoelectric response of the sample. This requires the quantitative calibration of torsional and buckling response of AFM. This method is validated by measuring the angular dependence of the in-plane piezoelectric response of a piece of piezoelectric α-quartz. The accurate determination of the amplitude and orientation of the in-plane piezoelectric response, without rotation, would greatly enhance the efficiency of lateral piezoelectric force microscopy.

Atomic force microscopy and confocal laser scanning microscopy on the cytoskeleton of permeabilised and embedded cells

International Nuclear Information System (INIS)

Meller, Karl; Theiss, Carsten

2006-01-01

We describe a technical method of cell permeabilisation and embedding to study the organisation and distribution of intracellular proteins with aid of atomic force microscopy and confocal laser scanning microscopy in identical areas. While confocal laser scanning microscopy is useful for the identification of certain proteins subsequent labelling with markers or antibodies, atomic force microscopy allows the observation of macromolecular structures in fixed and living cells. To demonstrate the field of application of this preparatory technique, cells were permeabilised, fixed, and the actin cytoskeleton was stained with phalloidin-rhodamine. Confocal laser scanning microscopy was used to show the organisation of these microfilaments, e.g. geodesic dome structures. Thereafter, cells were embedded in Durcupan water-soluble resin, followed by UV-polymerisation of resin at 4 o C. This procedure allowed intracellular visualisation of the cell nucleus or cytoskeletal elements by atomic force microscopy, for instance to analyse the globular organisation of actin filaments. Therefore, this method offers a great potential to combine both microscopy techniques in order to understand and interpret intracellular protein relations, for example, the biochemical and morphological interaction of the cytoskeleton

Direct measurements of intermolecular forces by chemical force microscopy

Science.gov (United States)

Vezenov, Dmitri Vitalievich

1999-12-01

Detailed description of intermolecular forces is key to understanding a wide range of phenomena from molecular recognition to materials failure. The unique features of atomic force microscopy (AFM) to make point contact force measurements with ultra high sensitivity and to generate spatial maps of surface topography and forces have been extended to include measurements between well-defined organic molecular groups. Chemical modification of AFM probes with self-assembled monolayers (SAMs) was used to make them sensitive to specific molecular interactions. This novel chemical force microscopy (CFM) technique was used to probe forces between different molecular groups in a range of environments (vacuum, organic liquids and aqueous solutions); measure surface energetics on a nanometer scale; determine pK values of the surface acid and base groups; measure forces to stretch and unbind a short synthetic DNA duplex and map the spatial distribution of specific functional groups and their ionization state. Studies of adhesion forces demonstrated the important contribution of hydrogen bonding to interactions between simple organic functionalities. The chemical identity of the tip and substrate surfaces as well as the medium had a dramatic effect on adhesion between model monolayers. A direct correlation between surface free energy and adhesion forces was established. The adhesion between epoxy polymer and model mixed SAMs varied with the amount of hydrogen bonding component in the monolayers. A consistent interpretation of CFM measurements in polar solvents was provided by contact mechanics models and intermolecular force components theory. Forces between tips and surfaces functionalized with SAMs terminating in acid or base groups depended on their ionization state. A novel method of force titration was introduced for highly local characterization of the pK's of surface functional groups. The pH-dependent changes in friction forces were exploited to map spatially the

Synchronizing atomic force microscopy force mode and fluorescence microscopy in real time for immune cell stimulation and activation studies

Energy Technology Data Exchange (ETDEWEB)

Cazaux, Séverine; Sadoun, Anaïs; Biarnes-Pelicot, Martine; Martinez, Manuel; Obeid, Sameh [Aix Marseille Université, LAI UM 61, Marseille F-13288 (France); Inserm, UMR-S 1067, Marseille F-13288 (France); CNRS, UMR 7333, Marseille F-13288 (France); Bongrand, Pierre [Aix Marseille Université, LAI UM 61, Marseille F-13288 (France); Inserm, UMR-S 1067, Marseille F-13288 (France); CNRS, UMR 7333, Marseille F-13288 (France); APHM, Hôpital de la Conception, Laboratoire d’Immunologie, Marseille F-13385 (France); Limozin, Laurent [Aix Marseille Université, LAI UM 61, Marseille F-13288 (France); Inserm, UMR-S 1067, Marseille F-13288 (France); CNRS, UMR 7333, Marseille F-13288 (France); Puech, Pierre-Henri, E-mail: pierre-henri.puech@inserm.fr [Aix Marseille Université, LAI UM 61, Marseille F-13288 (France); Inserm, UMR-S 1067, Marseille F-13288 (France); CNRS, UMR 7333, Marseille F-13288 (France)

2016-01-15

A method is presented for combining atomic force microscopy (AFM) force mode and fluorescence microscopy in order to (a) mechanically stimulate immune cells while recording the subsequent activation under the form of calcium pulses, and (b) observe the mechanical response of a cell upon photoactivation of a small G protein, namely Rac. Using commercial set-ups and a robust signal coupling the fluorescence excitation light and the cantilever bending, the applied force and activation signals were very easily synchronized. This approach allows to control the entire mechanical history of a single cell up to its activation and response down to a few hundreds of milliseconds, and can be extended with very minimal adaptations to other cellular systems where mechanotransduction is studied, using either purely mechanical stimuli or via a surface bound specific ligand. - Highlights: • A signal coupling AFM and fluorescence microscopy was characterized for soft cantilevers. • It can be used as an intrinsic timer to synchronize images and forces. • Mechanical stimulation of single immune cells while recording calcium fluxes was detailed. • Light-induced mechanical modifications of lymphocytes using a PA-Rac protein were demonstrated. • The precautions and limitations of use of this effect were presented.

Simultaneous differential spinning disk fluorescence optical sectioning microscopy and nanomechanical mapping atomic force microscopy

International Nuclear Information System (INIS)

Miranda, Adelaide; De Beule, Pieter A. A.; Martins, Marco

2015-01-01

Combined microscopy techniques offer the life science research community a powerful tool to investigate complex biological systems and their interactions. Here, we present a new combined microscopy platform based on fluorescence optical sectioning microscopy through aperture correlation microscopy with a Differential Spinning Disk (DSD) and nanomechanical mapping with an Atomic Force Microscope (AFM). The illumination scheme of the DSD microscope unit, contrary to standard single or multi-point confocal microscopes, provides a time-independent illumination of the AFM cantilever. This enables a distortion-free simultaneous operation of fluorescence optical sectioning microscopy and atomic force microscopy with standard probes. In this context, we discuss sample heating due to AFM cantilever illumination with fluorescence excitation light. Integration of a DSD fluorescence optical sectioning unit with an AFM platform requires mitigation of mechanical noise transfer of the spinning disk. We identify and present two solutions to almost annul this noise in the AFM measurement process. The new combined microscopy platform is applied to the characterization of a DOPC/DOPS (4:1) lipid structures labelled with a lipophilic cationic indocarbocyanine dye deposited on a mica substrate

Simultaneous differential spinning disk fluorescence optical sectioning microscopy and nanomechanical mapping atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Miranda, Adelaide; De Beule, Pieter A. A., E-mail: pieter.de-beule@inl.int [Applied Nano-Optics Laboratory, International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, s/n, 4715-330 Braga (Portugal); Martins, Marco [Nano-ICs Group, International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, s/n, 4715-330 Braga (Portugal)

2015-09-15

Combined microscopy techniques offer the life science research community a powerful tool to investigate complex biological systems and their interactions. Here, we present a new combined microscopy platform based on fluorescence optical sectioning microscopy through aperture correlation microscopy with a Differential Spinning Disk (DSD) and nanomechanical mapping with an Atomic Force Microscope (AFM). The illumination scheme of the DSD microscope unit, contrary to standard single or multi-point confocal microscopes, provides a time-independent illumination of the AFM cantilever. This enables a distortion-free simultaneous operation of fluorescence optical sectioning microscopy and atomic force microscopy with standard probes. In this context, we discuss sample heating due to AFM cantilever illumination with fluorescence excitation light. Integration of a DSD fluorescence optical sectioning unit with an AFM platform requires mitigation of mechanical noise transfer of the spinning disk. We identify and present two solutions to almost annul this noise in the AFM measurement process. The new combined microscopy platform is applied to the characterization of a DOPC/DOPS (4:1) lipid structures labelled with a lipophilic cationic indocarbocyanine dye deposited on a mica substrate.

Investigation of graphite composite anodes surfaces by atomic force microscopy and related techniques

Energy Technology Data Exchange (ETDEWEB)

Hirasawa, Karen Akemi; Nishioka, Keiko; Sato, Tomohiro; Yamaguchi, Shoji; Mori, Shoichiro [Mitsubishi Chemical Corp., Tsukuba Research Center, Ibaraki (Japan)

1997-11-01

The surface of a synthetic graphite (KS-44) and polyvinylidene difluoride binder (PVDF) anode for lithium-ion secondary batteries is imaged using atomic force microscopy (AFM) and several related scanning probe microscope (SPM) instruments including: dynamic force microscopy (DFM), friction force microscopy (FFM), laterally-modulated friction force microscopy (LM-FFM), visco-elasticity atomic force microscopy (VE-AFM), and AFM/simultaneous current measurement mode (SCM). DFM is found to be an exceptional mode for topographic imaging while FFM results in the clearest contrast distinction between PVDF binder and KS-44 graphite regions. (orig.)

System analysis of force feedback microscopy

International Nuclear Information System (INIS)

Rodrigues, Mario S.; Costa, Luca; Chevrier, Joël; Comin, Fabio

2014-01-01

It was shown recently that the Force Feedback Microscope (FFM) can avoid the jump-to-contact in Atomic force Microscopy even when the cantilevers used are very soft, thus increasing force resolution. In this letter, we explore theoretical aspects of the associated real time control of the tip position. We take into account lever parameters such as the lever characteristics in its environment, spring constant, mass, dissipation coefficient, and the operating conditions such as controller gains and interaction force. We show how the controller parameters are determined so that the FFM functions at its best and estimate the bandwidth of the system under these conditions

System analysis of force feedback microscopy

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Mario S. [CFMC/Dep. de Física, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Costa, Luca [European Synchrotron Radiation Facility, 6 rue Jules Horowitz BP 220, 38043 Grenoble Cedex (France); Université Joseph Fourier BP 53, 38041 Grenoble Cedex 9 (France); Chevrier, Joël [European Synchrotron Radiation Facility, 6 rue Jules Horowitz BP 220, 38043 Grenoble Cedex (France); Université Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Comin, Fabio [European Synchrotron Radiation Facility, 6 rue Jules Horowitz BP 220, 38043 Grenoble Cedex (France)

2014-02-07

It was shown recently that the Force Feedback Microscope (FFM) can avoid the jump-to-contact in Atomic force Microscopy even when the cantilevers used are very soft, thus increasing force resolution. In this letter, we explore theoretical aspects of the associated real time control of the tip position. We take into account lever parameters such as the lever characteristics in its environment, spring constant, mass, dissipation coefficient, and the operating conditions such as controller gains and interaction force. We show how the controller parameters are determined so that the FFM functions at its best and estimate the bandwidth of the system under these conditions.

Spectroscopy and atomic force microscopy of biomass.

Science.gov (United States)

Tetard, L; Passian, A; Farahi, R H; Kalluri, U C; Davison, B H; Thundat, T

2010-05-01

Scanning probe microscopy has emerged as a powerful approach to a broader understanding of the molecular architecture of cell walls, which may shed light on the challenge of efficient cellulosic ethanol production. We have obtained preliminary images of both Populus and switchgrass samples using atomic force microscopy (AFM). The results show distinctive features that are shared by switchgrass and Populus. These features may be attributable to the lignocellulosic cell wall composition, as the collected images exhibit the characteristic macromolecular globule structures attributable to the lignocellulosic systems. Using both AFM and a single case of mode synthesizing atomic force microscopy (MSAFM) to characterize Populus, we obtained images that clearly show the cell wall structure. The results are of importance in providing a better understanding of the characteristic features of both mature cells as well as developing plant cells. In addition, we present spectroscopic investigation of the same samples.

Comparing the photocatalytic activity of TiO2 at macro- and microscopic scales

DEFF Research Database (Denmark)

Torras-Rosell, Antoni; Johannsen, Sabrina Rostgaard; Dirscherl, Kai

2016-01-01

. The photocatalytic properties of TiO2 at macro- and microscopic scales are investigated by comparing photocatalytic degradation of acetone and electrochemical experiments to Kelvin probe force microscopy. The good agreement between the macro- and microscopic experiments suggests that Kelvin probe force microscopy...

Electrostatic Force Microscopy of Self Assembled Peptide Structures

DEFF Research Database (Denmark)

Clausen, Casper Hyttel; Dimaki, Maria; Pantagos, Spyros P.

2011-01-01

In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures, such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures. In partic......In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures, such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures...

Identification and ultrastructural imaging of photodynamic therapy-induced microfilaments by atomic force microscopy

International Nuclear Information System (INIS)

Jung, Se-Hui; Park, Jin-Young; Yoo, Je-Ok; Shin, Incheol; Kim, Young-Myeong; Ha, Kwon-Soo

2009-01-01

Atomic force microscopy (AFM) is an emerging technique for imaging biological samples at subnanometer resolution; however, the method is not widely used for cell imaging because it is limited to analysis of surface topology. In this study, we demonstrate identification and ultrastructural imaging of microfilaments using new approaches based on AFM. Photodynamic therapy (PDT) with a new chlorin-based photosensitizer DH-II-24 induced cell shrinkage, membrane blebbing, and reorganization of cytoskeletons in bladder cancer J82 cells. We investigated cytoskeletal changes using confocal microscopy and atomic force microscopy. Extracellular filaments formed by PDT were analyzed with a tandem imaging approach based on confocal microscopy and atomic force microscopy. Ultrathin filaments that were not visible by confocal microscopy were identified as microfilaments by on-stage labeling/imaging using atomic force microscopy. Furthermore, ultrastructural imaging revealed that these microfilaments had a stranded helical structure. Thus, these new approaches were useful for ultrastructural imaging of microfilaments at the molecular level, and, moreover, they may help to overcome the current limitations of fluorescence-based microscopy and atomic force microscopy in cell imaging.

The contribution of the electrostatic proximity force to atomic force microscopy with insulators

International Nuclear Information System (INIS)

Stanley Czarnecki, W.; Schein, L.B.

2005-01-01

Measurements, using atomic force microscopy, of the force and force derivative on a charged insulating micron sized sphere as a function of gap between the sphere and a conductive plane have revealed attractive forces at finite gaps that are larger than predicted by either van der Waals or conventional electrostatic forces. We suggest that these observations may be due to an electrostatic force that we have identified theoretically and call the proximity force. This proximity force is due to the discrete charges on the surface of the sphere in close proximity to the plane

The contribution of the electrostatic proximity force to atomic force microscopy with insulators

Energy Technology Data Exchange (ETDEWEB)

Stanley Czarnecki, W. [Aetas Technology Corporation, P.O. Box 53398, Irvine, CA 92619-3398 (United States); IBM Corporation, 5600 Cottle Rd., Building 13, San Jose, CA 95193 (United States); Schein, L.B. [Aetas Technology Corporation, P.O. Box 53398, Irvine, CA 92619-3398 (United States)]. E-mail: schein@prodigy.net

2005-05-16

Measurements, using atomic force microscopy, of the force and force derivative on a charged insulating micron sized sphere as a function of gap between the sphere and a conductive plane have revealed attractive forces at finite gaps that are larger than predicted by either van der Waals or conventional electrostatic forces. We suggest that these observations may be due to an electrostatic force that we have identified theoretically and call the proximity force. This proximity force is due to the discrete charges on the surface of the sphere in close proximity to the plane.

Surface chemical reactions probed with scanning force microscopy

NARCIS (Netherlands)

Werts, M.P L; van der Vegte, E.W.; Hadziioannou, G

1997-01-01

In this letter we report the study of surface chemical reactions with scanning force microscopy (SFM) with chemical specificity. Using chemically modified SFM probes, we can determine the local surface reaction conversion during a chemical surface modification. The adhesion forces between a

Fabrication and atomic force microscopy/friction force microscopy (AFM/FFM) studies of polyacrylamide-carbon nanotubes (PAM-CNTs) copolymer thin films

International Nuclear Information System (INIS)

Li Xuefeng; Guan Wenchao; Yan Haibiao; Huang Lan

2004-01-01

A novel polyacrylamide-carbon nanotubes (PAM-CNTs) copolymer has been prepared by ultraviolet radiation initiated polymerization. The PAM-CNTs copolymer was characterized by the instruments of Fourier transform infrared spectroscopy, UV-vis absorbance spectra, fluorescence spectra and transmission electron microscope. The morphology and microtribological properties of PAM-CNTs thin films on mica were investigated by atomic force microscopy/friction force microscopy (AFM/FFM). The friction of the films was stable with the change of applied load and the friction coefficient decreased significantly as the CNTs addition. The results show that the rigid rod-like CNTs in polymer would enhance load-bearing and anti-wear properties of the thin films

Interactive forces between lignin and cellulase as determined by atomic force microscopy

OpenAIRE

Qin, Chengrong; Clarke, Kimberley; Li, Kecheng

2014-01-01

Background Lignin is a complex polymer which inhibits the enzymatic conversion of cellulose to glucose in lignocellulose biomass for biofuel production. Cellulase enzymes irreversibly bind to lignin, deactivating the enzyme and lowering the overall activity of the hydrolyzing reaction solution. Within this study, atomic force microscopy (AFM) is used to compare the adhesion forces between cellulase and lignin with the forces between cellulase and cellulose, and to study the moiety groups invo...

Mechanic-electrical transformations in the Kelvin method

Energy Technology Data Exchange (ETDEWEB)

Zharkikh, Yu. S., E-mail: yurzhar@gmail.com [Faculty of Radio Physics, Electronics and Computer Systems, Taras Shevchenko National University of Kyiv, 4G, Ave. Academician Glushkov, 03127, Kyiv (Ukraine); Lysochenko, S.V., E-mail: lys@univ.kiev.ua [Institute of High Technologies, Taras Shevchenko National University of Kyiv, 4G, Ave. Academician Glushkov, 03127, Kyiv (Ukraine)

2017-04-01

Highlights: • Used in Kelvin method dynamic capacitor is a mechanic-electrical transformer. • The oscillations of its plate are source of extraneous forces which cause the appearance of an electric current. • The signal is caused not by the contact potential difference, but by oscillation in the screening conditions of charge in the dynamic capacitor gap. • Combining the Kelvin method with electron emission methods to determine the work function may lead to incorrectness. - Abstract: To explain the initiation mechanism of alternating current in an electric circuit containing the dynamic capacitor a model of mechanic- electrical transformation is suggested to use. In such a model, electric charges disposed between the capacitor plates serve as a cause of measured signal in contrast to the contact potential difference, which is considered as the main base in the Kelvin’s model. If one of the plates moves periodically, then the conditions of the charges screening are changed and thereby the capacitor recharging current is arise. The measuring is based on compensation of the recharging current by current, which generated by a source of electromotive force (EMF). The compensation voltage depends on both the distribution of ions or dipoles over the studied surface and the charges creating the surface potential barrier. This voltage is independent on the bulk electro-physical characteristics of a solid.

Algorithms for Reconstruction of Undersampled Atomic Force Microscopy Images Supplementary Material

DEFF Research Database (Denmark)

2017-01-01

Two Jupyter Notebooks showcasing reconstructions of undersampled atomic force microscopy images. The reconstructions were obtained using a variety of interpolation and reconstruction methods.......Two Jupyter Notebooks showcasing reconstructions of undersampled atomic force microscopy images. The reconstructions were obtained using a variety of interpolation and reconstruction methods....

Kelvin Life, Labours and Legacy

CERN Document Server

Flood, Raymond; Whitaker, Andrew

2008-01-01

Lord Kelvin was one of the greatest physicists of the Victorian era. Widely known for the development of the Kelvin scale of temperature measurement, Kelvin's interests ranged across thermodynamics, the age of the Earth, the laying of the first transatlantic telegraph cable, not to mention inventions such as an improved maritime compass and a sounding device which allowed depths to be taken both quickly and while the ship was moving. He was an academic engaged in fundamentalresearch, while also working with industry and technological advances. He corresponded and collaborated with other eminen

Local adhesive surface properties studied by force microscopy

International Nuclear Information System (INIS)

Lekka, M.; Lekki, J.; Marszalek, M.; Stachura, Z.; Cleff, B.

1998-01-01

Scanning force microscopy was used in the contact mode to determine the adhesion force between a mica surface and a silicon nitride tip. The measurements were performed in an aqueous solution of sodium and calcium chlorides. The adhesion force according to the Derjaguin-Landau-Verwey-Overbeek theory depends on the competition between two kinds of forces: van der Waals and electrostatic 'double layer'. Two different curves of adhesion force versus salt concentration were obtained from the experiment with monovalent and divalent ions. The tip-surface adhesion force was determined from a statistical analysis of data obtained from the force vs. distance retracting curves. (author)

Friction of ice measured using lateral force microscopy

International Nuclear Information System (INIS)

Bluhm, Hendrik; Inoue, Takahito; Salmeron, Miquel

2000-01-01

The friction of nanometer thin ice films grown on mica substrates is investigated using atomic force microscopy (AFM). Friction was found to be of similar magnitude as the static friction of ice reported in macroscopic experiments. The possible existence of a lubricating film of water due to pressure melting, frictional heating, and surface premelting is discussed based on the experimental results using noncontact, contact, and lateral force microscopy. We conclude that AFM measures the dry friction of ice due to the low scan speed and the squeezing out of the water layer between the sharp AFM tip and the ice surface. (c) 2000 The American Physical Society

Local work function analysis of Pt/TiO2 photocatalyst by a Kelvin probe force microscope

International Nuclear Information System (INIS)

Hiehata, K; Sasahara, A; Onishi, H

2007-01-01

Nanometre-sized Pt clusters were prepared on a TiO 2 (110)-(1 x 1) surface, and the lateral distribution of work function was examined by using a Kelvin probe force microscope. Local work function on the Pt clusters was smaller than that on the surrounding TiO 2 surface. Assuming that the dipole moments which perturb the work function are produced by uneven electron distribution, the decrease of the work function indicates electron transfer from the clusters to the TiO 2 surface. After decomposition of pivalate anions on the surfaces by UV irradiation, the work function increased on some Pt clusters. It is known that holes photoexcited in TiO 2 attach to pivalate anions to cause a decomposition reaction. Hence the increase of the observed work function by UV irradiation can be ascribed to the trapping of the accompanying electrons to the Pt clusters

Resolving amorphous solid-liquid interfaces by atomic force microscopy

International Nuclear Information System (INIS)

Burson, Kristen M.; Gura, Leonard; Kell, Burkhard; Büchner, Christin; Lewandowski, Adrian L.; Heyde, Markus; Freund, Hans-Joachim

2016-01-01

Recent advancements in liquid atomic force microscopy make it an ideal technique for probing the structure of solid-liquid interfaces. Here, we present a structural study of a two-dimensional amorphous silica bilayer immersed in an aqueous solution utilizing liquid atomic force microscopy with sub-nanometer resolution. Structures show good agreement with atomically resolved ultra-high vacuum scanning tunneling microscopy images obtained on the same sample system, owing to the structural stability of the silica bilayer and the imaging clarity from the two-dimensional sample system. Pair distance histograms of ring center positions are utilized to develop quantitative metrics for structural comparison, and the physical origin of pair distance histogram peaks is addressed by direct assessment of real space structures.

Magnetic elements for switching magnetization magnetic force microscopy tips

International Nuclear Information System (INIS)

Cambel, V.; Elias, P.; Gregusova, D.; Martaus, J.; Fedor, J.; Karapetrov, G.; Novosad, V.

2010-01-01

Using combination of micromagnetic calculations and magnetic force microscopy (MFM) imaging we find optimal parameters for novel magnetic tips suitable for switching magnetization MFM. Switching magnetization MFM is based on two-pass scanning atomic force microscopy with reversed tip magnetization between the scans. Within the technique the sum of the scanned data with reversed tip magnetization depicts local atomic forces, while their difference maps the local magnetic forces. Here we propose the design and calculate the magnetic properties of tips suitable for this scanning probe technique. We find that for best performance the spin-polarized tips must exhibit low magnetic moment, low switching fields, and single-domain state at remanence. The switching field of such tips is calculated and optimum shape of the Permalloy elements for the tips is found. We show excellent correspondence between calculated and experimental results for Py elements.

PREFACE: Kelvin and Ireland

Science.gov (United States)

Flood, Raymond; McCartney, Mark; Whitaker, Andrew

2009-07-01

Sir Joseph Larmor unveiling the Kelvin memorial in the Botanic Gardens, Belfast on a rainy day in 1913 Sir Joseph Larmor unveiling the Kelvin memorial in the Botanic Gardens, Belfast on a rainy day in 1913 © The Ulster Museum: Hogg collection William Thomson, later Lord Kelvin, was born in Belfast in 1824, and his family had lived near Ballynahinch in the north of Ireland, quite close to Belfast, from the seventeenth century. At the time of Kelvin's birth, James Thomson, his father, was Professor of Mathematics at the Belfast Royal Academical Institution (Inst). However, following the death of his wife in 1830, James took up a new position as Professor at the University of Glasgow, and he and his children moved there in 1832. Apart from three years studying at Cambridge, and a very brief period immediately afterwards travelling and teaching in Cambridge, Kelvin was to spend the rest of his life in Glasgow, where he occupied the Chair of Natural Philosophy (or Physics) for 53 years. The natural assumption might be that his birth in Ireland was irrelevant to Kelvin's life and work, and that the fine monument erected in his honour in Belfast's Botanic Gardens, which is pictured on the front cover of this volume, was more a demonstration of civic pride than a recognition of an aspect of Kelvin's life which was important to him. The purpose of the meeting was to demon strate that this was not the case, that, great Glaswegian as he undoubtedly became, Kelvin always delighted in the title of Irishman. The influence of his father, very much an Ulsterman, was immense, and Kelvin and his siblings were to follow his non-sectarian and reforming approach. Also important for Kelvin was his Christian upbringing, which began in Belfast, and his beliefs were to play a role of importance in his life and indeed in much of his most important work, in particular that on thermodynamics. Two of his siblings returned to Belfast and spent much of their lives there, and Kelvin was a

Automated force controller for amplitude modulation atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Miyagi, Atsushi, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr; Scheuring, Simon, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr [U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, 13009 Marseille (France)

2016-05-15

Atomic Force Microscopy (AFM) is widely used in physics, chemistry, and biology to analyze the topography of a sample at nanometer resolution. Controlling precisely the force applied by the AFM tip to the sample is a prerequisite for faithful and reproducible imaging. In amplitude modulation (oscillating) mode AFM, the applied force depends on the free and the setpoint amplitudes of the cantilever oscillation. Therefore, for keeping the applied force constant, not only the setpoint amplitude but also the free amplitude must be kept constant. While the AFM user defines the setpoint amplitude, the free amplitude is typically subject to uncontrollable drift, and hence, unfortunately, the real applied force is permanently drifting during an experiment. This is particularly harmful in biological sciences where increased force destroys the soft biological matter. Here, we have developed a strategy and an electronic circuit that analyzes permanently the free amplitude of oscillation and readjusts the excitation to maintain the free amplitude constant. As a consequence, the real applied force is permanently and automatically controlled with picoNewton precision. With this circuit associated to a high-speed AFM, we illustrate the power of the development through imaging over long-duration and at various forces. The development is applicable for all AFMs and will widen the applicability of AFM to a larger range of samples and to a larger range of (non-specialist) users. Furthermore, from controlled force imaging experiments, the interaction strength between biomolecules can be analyzed.

Detection of the fast Kelvin wave teleconnection due to El Niño-Southern Oscillation

Science.gov (United States)

Meyers, Steven D.; Melsom, Arne; Mitchum, Gary T.; O'Brien, James J.

1998-11-01

Previous analyses of the ocean state along the western American coast have often indicated unexpectedly slow and limited propagation of coastally trapped Kelvin waves associated with the El Niño-Southern Oscillation. In contrast, theoretical and numerical ocean models demonstrate that these Kelvin waves are a rapid and long-range teleconnection between the low- and high-latitude Pacific Ocean, strongly impacting both the surface coastal currents and nutrient upwelling. Sea level variations along the western coast of North America are reexamined under the assumption that tropically forced Kelvin waves are produced in bursts of several months duration. A cross-correlation analysis, restricted to mid-1982 to mid-1983, is performed between Galapagos Island and stations along western Central and North America. A coastally trapped Kelvin wave is revealed to propagate at a speed of 2-3 m s-1 from the tropical Pacific to the Aleutian Island Chain. The observed phase speed agrees with the estimated speed of a Kelvin wave based on the average density profile of the ocean near the coast. Weaker El Niño events in 1986/1987 and 1991/1992 appear to contain a combination of this remote signal and local wind forcing. The wave propagation speed calculated from the spectral phase is shown to be sensitive to the presence of other (noise) processes in the observations. This is demonstrated through an analysis of a synthetic sea level data set that contains many of the essential features of the real sea level data. A relatively small level of red noise can give a 100% expected error in the estimated propagation speed. This suggests a new explanation for this important inconsistency within dynamical oceanography.

Photoinduced force microscopy: A technique for hyperspectral nanochemical mapping

Science.gov (United States)

Murdick, Ryan A.; Morrison, William; Nowak, Derek; Albrecht, Thomas R.; Jahng, Junghoon; Park, Sung

2017-08-01

Advances in nanotechnology have intensified the need for tools that can characterize newly synthesized nanomaterials. A variety of techniques has recently been shown which combines atomic force microscopy (AFM) with optical illumination including tip-enhanced Raman spectroscopy (TERS), scattering-type scanning near-field optical microscopy (sSNOM), and photothermal induced resonance microscopy (PTIR). To varying degrees, these existing techniques enable optical spectroscopy with the nanoscale spatial resolution inherent to AFM, thereby providing nanochemical interrogation of a specimen. Here we discuss photoinduced force microscopy (PiFM), a recently developed technique for nanoscale optical spectroscopy that exploits image forces acting between an AFM tip and sample to detect wavelength-dependent polarization within the sample to generate absorption spectra. This approach enables ∼10 nm spatial resolution with spectra that show correlation with macroscopic optical absorption spectra. Unlike other techniques, PiFM achieves this high resolution with virtually no constraints on sample or substrate properties. The applicability of PiFM to a variety of archetypal systems is reported here, highlighting the potential of PiFM as a useful tool for a wide variety of industrial and academic investigations, including semiconducting nanoparticles, nanocellulose, block copolymers, and low dimensional systems, as well as chemical and morphological mixing at interfaces.

CFD simulation of Kelvin-Helmholtz instability

International Nuclear Information System (INIS)

Strubelj, L.; Tiselj, I.

2005-01-01

Kelvin-Helmholtz instability appears in stratified two-fluid flow at surface. When the relative velocity is higher than the critical relative velocity, the growth of waves occurs. The experiment of Thorpe [1] used as a benchmark in the present paper, is made in a rectangular glass tube filled with two immiscible fluids of various densities. We simulated the growth of instability with CFX-5.7 code and compared simulation with analytical solution. It was found that surface tension force, which stabilizes growth of waves, actually has a destabilizing effect in simulation, unless very small timestep and residual is used. In CFX code system of nonlinear Navier-Stokes equations is linearised and solved iterative in each timestep, until prescribed residual is achieved. On the other hand, simulation without surface tension force is more stable than analytical result predicts. (author)

Atomic force microscopy as a tool for the investigation of living cells.

Science.gov (United States)

Morkvėnaitė-Vilkončienė, Inga; Ramanavičienė, Almira; Ramanavičius, Arūnas

2013-01-01

Atomic force microscopy is a valuable and useful tool for the imaging and investigation of living cells in their natural environment at high resolution. Procedures applied to living cell preparation before measurements should be adapted individually for different kinds of cells and for the desired measurement technique. Different ways of cell immobilization, such as chemical fixation on the surface, entrapment in the pores of a membrane, or growing them directly on glass cover slips or on plastic substrates, result in the distortion or appearance of artifacts in atomic force microscopy images. Cell fixation allows the multiple use of samples and storage for a prolonged period; it also increases the resolution of imaging. Different atomic force microscopy modes are used for the imaging and analysis of living cells. The contact mode is the best for cell imaging because of high resolution, but it is usually based on the following: (i) image formation at low interaction force, (ii) low scanning speed, and (iii) usage of "soft," low resolution cantilevers. The tapping mode allows a cell to behave like a very solid material, and destructive shear forces are minimized, but imaging in liquid is difficult. The force spectroscopy mode is used for measuring the mechanical properties of cells; however, obtained results strongly depend on the cell fixation method. In this paper, the application of 3 atomic force microscopy modes including (i) contact, (ii) tapping, and (iii) force spectroscopy for the investigation of cells is described. The possibilities of cell preparation for the measurements, imaging, and determination of mechanical properties of cells are provided. The applicability of atomic force microscopy to diagnostics and other biomedical purposes is discussed.

Probing stem cell differentiation using atomic force microscopy

International Nuclear Information System (INIS)

Liang, Xiaobin; Shi, Xuetao; Ostrovidov, Serge; Wu, Hongkai; Nakajima, Ken

2016-01-01

Graphical abstract: - Highlights: • Atomic force microscopy (AFM) was developed to probe stem cell differentiation. • The mechanical properties of stem cells and their ECMs can be used to clearly distinguish specific stem cell-differentiated lineages. • AFM is a facile and useful tool for monitoring stem cell differentiation in a non-invasive manner. - Abstract: A real-time method using atomic force microscopy (AFM) was developed to probe stem cell differentiation by measuring the mechanical properties of cells and the extracellular matrix (ECM). The mechanical properties of stem cells and their ECMs can be used to clearly distinguish specific stem cell-differentiated lineages. It is clear that AFM is a facile and useful tool for monitoring the differentiation of stem cells in a non-invasive manner.

Probing stem cell differentiation using atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Liang, Xiaobin [Graduate School of Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8550 (Japan); Shi, Xuetao, E-mail: mrshixuetao@gmail.com [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Ostrovidov, Serge [WPI-Advanced Institute for Materials Research, Tohoku University, Sendai (Japan); Wu, Hongkai, E-mail: chhkwu@ust.hk [Department of Chemistry & Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Nakajima, Ken [Graduate School of Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8550 (Japan)

2016-03-15

Graphical abstract: - Highlights: • Atomic force microscopy (AFM) was developed to probe stem cell differentiation. • The mechanical properties of stem cells and their ECMs can be used to clearly distinguish specific stem cell-differentiated lineages. • AFM is a facile and useful tool for monitoring stem cell differentiation in a non-invasive manner. - Abstract: A real-time method using atomic force microscopy (AFM) was developed to probe stem cell differentiation by measuring the mechanical properties of cells and the extracellular matrix (ECM). The mechanical properties of stem cells and their ECMs can be used to clearly distinguish specific stem cell-differentiated lineages. It is clear that AFM is a facile and useful tool for monitoring the differentiation of stem cells in a non-invasive manner.

Drive frequency dependent phase imaging in piezoresponse force microscopy

International Nuclear Information System (INIS)

Bo Huifeng; Kan Yi; Lu Xiaomei; Liu Yunfei; Peng Song; Wang Xiaofei; Cai Wei; Xue Ruoshi; Zhu Jinsong

2010-01-01

The drive frequency dependent piezoresponse (PR) phase signal in near-stoichiometric lithium niobate crystals is studied by piezoresponse force microscopy. It is clearly shown that the local and nonlocal electrostatic forces have a great contribution to the PR phase signal. The significant PR phase difference of the antiparallel domains are observed at the contact resonances, which is related to the electrostatic dominated electromechanical interactions of the cantilever and tip-sample system. Moreover, the modulation voltage induced frequency shift at higher eigenmodes could be attributed to the change of indention force depending on the modulation amplitude with a piezoelectric origin. The PR phase of the silicon wafer is also measured for comparison. It is certificated that the electrostatic interactions are universal in voltage modulated scanning probe microscopy and could be extended to other phase imaging techniques.

Immunogold labels: cell-surface markers in atomic force microscopy

NARCIS (Netherlands)

Putman, Constant A.J.; Putman, C.A.J.; de Grooth, B.G.; Hansma, Paul K.; van Hulst, N.F.; Greve, Jan

1993-01-01

The feasibility of using immunogold labels as cell-surface markers in atomic force microscopy is shown in this paper. The atomic force microscope (AFM) was used to image the surface of immunogold-labeled human lymphocytes. The lymphocytes were isolated from whole blood and labeled by an indirect

Atomic force microscopy. A new method for atom identification and manipulation

International Nuclear Information System (INIS)

Abe, Masayuki; Sugimoto, Yoshiaki; Morita, Seizo

2007-01-01

Frequency modulation atomic force microscopy (FM-AFM) is a scanning probe technique that detects the interaction forces between the outermost atom of a sharp tip and the atoms at a surface to image the sample surface. It is expected that the FM-AFM can cover the research field which scanning tunneling microscopy does not provide. In this article, we would introduce FM-AFM experiments applied to site-specific force measurements and atom manipulation, including how to solve the problems to achieve precise FM-AFM measurements. (author)

Imaging stability in force-feedback high-speed atomic force microscopy

International Nuclear Information System (INIS)

Kim, Byung I.; Boehm, Ryan D.

2013-01-01

We studied the stability of force-feedback high-speed atomic force microscopy (HSAFM) by imaging soft, hard, and biological sample surfaces at various applied forces. The HSAFM images showed sudden topographic variations of streaky fringes with a negative applied force when collected on a soft hydrocarbon film grown on a grating sample, whereas they showed stable topographic features with positive applied forces. The instability of HSAFM images with the negative applied force was explained by the transition between contact and noncontact regimes in the force–distance curve. When the grating surface was cleaned, and thus hydrophilic by removing the hydrocarbon film, enhanced imaging stability was observed at both positive and negative applied forces. The higher adhesive interaction between the tip and the surface explains the improved imaging stability. The effects of imaging rate on the imaging stability were tested on an even softer adhesive Escherichia coli biofilm deposited onto the grating structure. The biofilm and planktonic cell structures in HSAFM images were reproducible within the force deviation less than ∼0.5 nN at the imaging rate up to 0.2 s per frame, suggesting that the force-feedback HSAFM was stable for various imaging speeds in imaging softer adhesive biological samples. - Highlights: ► We investigated the imaging stability of force-feedback HSAFM. ► Stable–unstable imaging transitions rely on applied force and sample hydrophilicity. ► The stable–unstable transitions are found to be independent of imaging rate

Sensing the facet orientation in silver nano-plates using scanning Kelvin probe microscopy in air

Energy Technology Data Exchange (ETDEWEB)

Abdellatif, M.H. [Department of Nanostructures, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); Physics Department, National Research Center, Elbehoos st., 12622, Dokki, Giza (Egypt); Salerno, M., E-mail: marco.salerno@iit.it [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); Polovitsyn, Anatolii [Department of Nanochemistry, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); Dipartimentodi Fisica, Università di Genova, via Dodecaneso 33, I-16146 Genova (Italy); Marras, Sergio [Department of Nanochemistry, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); De Angelis, Francesco [Department of Nanostructures, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy)

2017-05-01

Highlights: • The surface potential of drop cast nanocrystals was measured by SKPM in ambient air. • The nanocrystal facet work function was derived by theory. • By comparing theory and experiment we distinguished the nanocrystal facets. • Nanocrystal facet control is of practical interest for optoelectronic devices. - Abstract: The work function of nano-materials is important for a full characterization of their electronic properties. Because the band alignment, band bending and electronic noise are very sensitive to work function fluctuations, the dependence of the work function of nano-scale crystals on facet orientation can be a critical issue in optimizing optoelectronic devices based on these materials. We used scanning Kelvin probe microscopy to assess the local work function on samples of silver nano-plates at sub-micrometric spatial resolution. With the appropriate choice of the substrate and based on statistical analysis, it was possible to distinguish the surface potential of the different facets of silver nano-plates even if the measurements were done in ambient conditions without the use of vacuum. A phenomenological model was used to calculate the differences of facet work function of the silver nano-plates and the corresponding shift in Fermi level. This theoretical prediction and the experimentally observed difference in surface potential on the silver nano-plates were in good agreement. Our results show the possibility to sense the nano-crystal facets by appropriate choice of the substrate in ambient conditions.

Sensing the facet orientation in silver nano-plates using scanning Kelvin probe microscopy in air

International Nuclear Information System (INIS)

Abdellatif, M.H.; Salerno, M.; Polovitsyn, Anatolii; Marras, Sergio; De Angelis, Francesco

2017-01-01

Highlights: • The surface potential of drop cast nanocrystals was measured by SKPM in ambient air. • The nanocrystal facet work function was derived by theory. • By comparing theory and experiment we distinguished the nanocrystal facets. • Nanocrystal facet control is of practical interest for optoelectronic devices. - Abstract: The work function of nano-materials is important for a full characterization of their electronic properties. Because the band alignment, band bending and electronic noise are very sensitive to work function fluctuations, the dependence of the work function of nano-scale crystals on facet orientation can be a critical issue in optimizing optoelectronic devices based on these materials. We used scanning Kelvin probe microscopy to assess the local work function on samples of silver nano-plates at sub-micrometric spatial resolution. With the appropriate choice of the substrate and based on statistical analysis, it was possible to distinguish the surface potential of the different facets of silver nano-plates even if the measurements were done in ambient conditions without the use of vacuum. A phenomenological model was used to calculate the differences of facet work function of the silver nano-plates and the corresponding shift in Fermi level. This theoretical prediction and the experimentally observed difference in surface potential on the silver nano-plates were in good agreement. Our results show the possibility to sense the nano-crystal facets by appropriate choice of the substrate in ambient conditions.

Lord Kelvin's atmospheric electricity measurements

Science.gov (United States)

Aplin, Karen; Harrison, R. Giles; Trainer, Matthew; Hough, James

2013-04-01

Lord Kelvin (William Thomson), one of the greatest Victorian scientists, made a substantial but little-recognised contribution to geophysics through his work on atmospheric electricity. He developed sensitive instrumentation for measuring the atmospheric electric field, including invention of a portable electrometer, which made mobile measurements possible for the first time. Kelvin's measurements of the atmospheric electric field in 1859, made during development of the portable electrometer, can be used to deduce the substantial levels of particulate pollution blown over the Scottish island of Arran from the industrial mainland. Kelvin was also testing the electrometer during the largest solar flare ever recorded, the "Carrington event" in the late summer of 1859. Subsequently, Lord Kelvin also developed a water dropper sensor, and employed photographic techniques for "incessant recording" of the atmospheric electric field, which led to the long series of measurements recorded at UK observatories for the remainder of the 19th and much of the 20th century. These data sets have been valuable in both studies of historical pollution and cosmic ray effects on atmospheric processes.

Tapping mode atomic force microscopy in liquid

NARCIS (Netherlands)

Putman, Constant A.J.; Putman, C.A.J.; van der Werf, Kees; de Grooth, B.G.; van Hulst, N.F.; Greve, Jan

1994-01-01

We show that standard silicon nitride cantilevers can be used for tapping mode atomic force microscopy (AFM) in air, provided that the energy of the oscillating cantilever is sufficiently high to overcome the adhesion of the water layer. The same cantilevers are successfully used for tapping mode

Microparticle adhesion studies by atomic force microscopy

NARCIS (Netherlands)

Segeren, L.H.G.J.; Siebum, B.; Karssenberg, F.G.; Berg, van den J.W.A.; Vancso, G.J.

2002-01-01

Atomic force microscopy (AFM) is one of the most flexible and simple techniques for probing surface interactions. This article reviews AFM studies on particle adhesion. Special attention is paid to the characterization of roughness and its effect on adhesion. This is of importance when comparing the

Subsurface measurement of nanostructures on GaAs by electrostatic force microscopy

International Nuclear Information System (INIS)

Yamada, Fumihiko; Kamiya, Itaru

2013-01-01

The size of surface buried oxide nanostructures are measured by electrostatic force microscopy (EFM). In contrast to atomic force microscopy that cannot probe subsurface structures and thickness, we show that EFM data include information about the thickness of individual nanostructures, consequently allowing us to determine the thickness of buried nanostructures on semiconductor substrates. We further show that this measurement can be performed simultaneously with AFM using EFM modulation spectroscopy.

Micro-fabricated mechanical sensors for lateral molecular-force microscopy

Energy Technology Data Exchange (ETDEWEB)

Vicary, J.A., E-mail: james.vicary@bristol.ac.uk [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Ulcinas, A. [Research Centre for Microsystems and Nanotechnology, Kaunas University of Technology, LT-51369 Kaunas (Lithuania); Hoerber, J.K.H.; Antognozzi, M. [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Centre for Nanoscience and Quantum Information, University of Bristol, Tyndall Avenue, Bristol BS8 1FD (United Kingdom)

2011-11-15

Atomic force microscopy (AFM) has been very successful in measuring forces perpendicular to the sample plane. Here, we present the advantages of turning the AFM cantilever 90 Degree-Sign in order for it to be perpendicular to the sample. This rotation leads naturally to the detection of in-plane forces with some extra advantages with respect to the AFM orientation. In particular, the use of extremely small (1 {mu}m wide) and soft (k{approx_equal}10{sup -5} N/m) micro-fabricated cantilevers is demonstrated by recording their thermal power spectral density in ambient conditions and in liquid. These measurements lead to the complete characterisation of the sensors in terms of their stiffness and resonant frequency. Future applications, which will benefit from the use of this force microscopy technique, are also described. -- Highlights: Black-Right-Pointing-Pointer Micro-fabrication of ultra-soft silicon nitride sensors. Black-Right-Pointing-Pointer SEW detection system enables the use of extremely small cantilevers. Black-Right-Pointing-Pointer Choice of sensor geometry permits control of thermal excitations and axial rotations. Black-Right-Pointing-Pointer LMFM can be used in a force regime not previously associated with AFM.

High-speed atomic force microscopy combined with inverted optical microscopy for studying cellular events.

OpenAIRE

Suzuki, Yuki; Sakai, Nobuaki; Yoshida, Aiko; Uekusa, Yoshitsugu; Yagi, Akira; Imaoka, Yuka; Ito, Shuichi; Karaki, Koichi; Takeyasu, Kunio

2013-01-01

A hybrid atomic force microscopy (AFM)-optical fluorescence microscopy is a powerful tool for investigating cellular morphologies and events. However, the slow data acquisition rates of the conventional AFM unit of the hybrid system limit the visualization of structural changes during cellular events. Therefore, high-speed AFM units equipped with an optical/fluorescence detection device have been a long-standing wish. Here we describe the implementation of high-speed AFM coupled with an optic...

Nanoscale electrowetting effects observed by using friction force microscopy.

Science.gov (United States)

Revilla, Reynier; Guan, Li; Zhu, Xiao-Yang; Yang, Yan-Lian; Wang, Chen

2011-06-21

We report the study of electrowetting (EW) effects under strong electric field on poly(methyl methacrylate) (PMMA) surface by using friction force microscopy (FFM). The friction force dependence on the electric field at nanometer scale can be closely related to electrowetting process based on the fact that at this scale frictional behavior is highly affected by capillary phenomena. By measuring the frictional signal between a conductive atomic force microscopy (AFM) tip and the PMMA surface, the ideal EW region (Young-Lippmann equation) and the EW saturation were identified. The change in the interfacial contact between the tip and the PMMA surface with the electric field strength is closely associated with the transition from the ideal EW region to the EW saturation. In addition, a reduction of the friction coefficient was observed when increasing the applied electric field in the ideal EW region. © 2011 American Chemical Society

Nanoparticle sizing: a comparative study using atomic force microscopy, transmission electron microscopy, and ferromagnetic resonance

International Nuclear Information System (INIS)

Lacava, L.M.; Lacava, B.M.; Azevedo, R.B.; Lacava, Z.G.M.; Buske, N.; Tronconi, A.L.; Morais, P.C.

2001-01-01

Atomic force microscopy (AFM), transmission electron microscopy (TEM), and ferromagnetic resonance (FMR) were used to unfold the nanoparticle size of a ferrofluid sample. Compared to TEM, the AFM method showed a nanoparticle diameter (D m ) reduction of 20% and standard deviation (σ) increase of 15%. The differences in D m and σ were associated with the AFM tip and the nanoparticle concentration on the substrate

Capillary force between wetted nanometric contacts and its application to atomic force microscopy.

Science.gov (United States)

Crassous, Jérôme; Ciccotti, Matteo; Charlaix, Elisabeth

2011-04-05

We extend to the case of perfect wetting the exact calculation of Orr et al. (J. Fluid. Mech. 1975, 67, 723) for a pendular ring connecting two dry surfaces. We derive an approximate analytical expression for the capillary force between two highly curved surfaces covered by a wetting liquid film. The domain of validity of this expression is assessed and extended by a custom-made numerical simulation based on the full exact mathematical description. In the case of attractive liquid-solid van der Waals interactions, the capillary force increases monotonically with decreasing vapor pressure up to several times its saturation value. This accurate description of the capillary force makes it possible to estimate the adhesion force between wet nanoparticles; it can also be used to quantitatively interpret pull-off forces measured by atomic force microscopy.

Growth and structure of water on SiO2 films on Si investigated byKelvin probe microscopy and in situ X-ray Spectroscopies

Energy Technology Data Exchange (ETDEWEB)

Verdaguer, A.; Weis, C.; Oncins, G.; Ketteler, G.; Bluhm, H.; Salmeron, M.

2007-06-14

The growth of water on thin SiO{sub 2} films on Si wafers at vapor pressures between 1.5 and 4 torr and temperatures between -10 and 21 C has been studied in situ using Kelvin Probe Microscopy and X-ray photoemission and absorption spectroscopies. From 0 to 75% relative humidity (RH) water adsorbs forming a uniform film 4-5 layers thick. The surface potential increases in that RH range by about 400 mV and remains constant upon further increase of the RH. Above 75% RH the water film grows rapidly, reaching 6-7 monolayers at around 90% RH and forming a macroscopic drop near 100%. The O K-edge near-edge X-ray absorption spectrum around 75% RH is similar to that of liquid water (imperfect H-bonding coordination) at temperatures above 0 C and ice-like below 0 C.

The SAO and Kelvin waves in the EuroGRIPS GCMS and the UK Met. Office analyses

Directory of Open Access Journals (Sweden)

M. Amodei

Full Text Available We compare the tropical oscillations and planetary scale Kelvin waves in four troposphere-stratosphere climate models and the assimilated dataset produced by the United Kingdom Meteorological Office (UKMO. The comparison has been made in the GRIPS framework "GCM-Reality Intercomparison Project for SPARC", where SPARC is Stratospheric Processes and their Role in Climate, a project of the World Climate Research Program. The four models evaluated are European members of GRIPS: the UKMO Unified Model (UM, the model of the Free University in Berlin (FUB–GCM, the ARPEGE-climat model of the French National Centre for Meteorological Research (CNRM, and the Extended UGAMP GCM (EUGCM of the Centre for Global Atmospheric Modelling (CGAM. The integrations were performed with different, but annually periodic external conditions (e.g., sea-surface temperature, sea ice, and incoming solar radiation. The structure of the tropical winds and the strengths of the Kelvin waves are examined. In the analyses where the SAO (Semi-Annual Oscillation and the QBO (Quasi-Biennal Oscillation are reasonably well captured, the amplitude of these analysed Kelvin waves is close to that observed in independent data from UARS (Upper Atmosphere Research Satellite. In agreement with observations, the Kelvin waves generated in the models propagate into the middle atmosphere as wave packets, consistent with a convective forcing origin. In three of the models, slow Kelvin waves propagate too high and their amplitudes are overestimated in the upper stratosphere and in the mesosphere, the exception is the UM which has weaker waves. None of the modelled waves are sufficient to force realistic eastward phases of the QBO or SAO. Although the SAO is represented by all models, only two of them are able to generate westerlies between 10 hPa and 50 hPa. The importance of the role played in the SAO by unresolved gravity waves is emphasized. Although it exhibits some unrealistic features, the

The SAO and Kelvin waves in the EuroGRIPS GCMS and the UK Met. Office analyses

Directory of Open Access Journals (Sweden)

M. Amodei

2001-01-01

Full Text Available We compare the tropical oscillations and planetary scale Kelvin waves in four troposphere-stratosphere climate models and the assimilated dataset produced by the United Kingdom Meteorological Office (UKMO. The comparison has been made in the GRIPS framework "GCM-Reality Intercomparison Project for SPARC", where SPARC is Stratospheric Processes and their Role in Climate, a project of the World Climate Research Program. The four models evaluated are European members of GRIPS: the UKMO Unified Model (UM, the model of the Free University in Berlin (FUB–GCM, the ARPEGE-climat model of the French National Centre for Meteorological Research (CNRM, and the Extended UGAMP GCM (EUGCM of the Centre for Global Atmospheric Modelling (CGAM. The integrations were performed with different, but annually periodic external conditions (e.g., sea-surface temperature, sea ice, and incoming solar radiation. The structure of the tropical winds and the strengths of the Kelvin waves are examined. In the analyses where the SAO (Semi-Annual Oscillation and the QBO (Quasi-Biennal Oscillation are reasonably well captured, the amplitude of these analysed Kelvin waves is close to that observed in independent data from UARS (Upper Atmosphere Research Satellite. In agreement with observations, the Kelvin waves generated in the models propagate into the middle atmosphere as wave packets, consistent with a convective forcing origin. In three of the models, slow Kelvin waves propagate too high and their amplitudes are overestimated in the upper stratosphere and in the mesosphere, the exception is the UM which has weaker waves. None of the modelled waves are sufficient to force realistic eastward phases of the QBO or SAO. Although the SAO is represented by all models, only two of them are able to generate westerlies between 10 hPa and 50 hPa. The importance of the role played in the SAO by unresolved gravity waves is emphasized. Although it exhibits some unrealistic features, the

Characterization of electronic charged states of P-doped Si quantum dots using AFM/Kelvin probe

International Nuclear Information System (INIS)

Makihara, Katsunori; Xu, Jun; Ikeda, Mitsuhisa; Murakami, Hideki; Higashi, Seiichiro; Miyazaki, Seiichi

2006-01-01

Phosphorous doping to Si quantum dots was performed by a pulse injection of 1% PH 3 diluted with He during the dot formation on thermally grown SiO 2 from thermal decomposition of pure SiH 4 , and electron charging to and discharging from P-doped Si dots were studied to characterize their electronic charged states using a Kelvin probe technique in atomic force microscopy (AFM). The potential change corresponding to the extraction of one electron from each of the P-doped Si dots was observed after applying a tip bias as low as + 0.2 V while for undoped Si dots, with almost the same size as P-doped Si dots, almost the same amount of the potential change was detectable only when the tip bias was increased to ∼ 1 V. It is likely that, for P-doped Si dots, the electron extraction from the conduction band occurs and results in a positively charged state with ionized P donor

Microstructural and micromechanical characterisation of TiAl alloys using atomic force microscopy and nanoindentation

International Nuclear Information System (INIS)

Gebhard, S.; Pyczak, F.; Goeken, M.

2009-01-01

Different microstructures were generated in the Ti-45Al-4.6Nb-0.2B-0.2C and Ti-45Al-1Cr alloys (at.%) by heat treatment. The microstructures were investigated using nanoindentation and atomic force microscopy which was compared with transmission electron microscopy. Topographic contrast is usually used for phase identification in the atomic force microscope. However, it was found that the topographic order of the phases changes with different microstructures and specimen preparations. Nanoindentation measurements provided local hardness values not obtainable by other methods and enabled clear distinction of the phases. The hardness values can give information on surrounding microstructure and solid solution hardening. The mean lamellar spacing of the colonies was measured using both atomic force microscopy and transmission electron microscopy. Atomic force microscopy was found to be suitable to determine the spacing between α 2 /γ-interfaces offering the advantages of easier sample preparation and fewer specimens compared to evaluation by TEM analysis.

Structural analysis of γ radiation-induced chromosomal aberrations observed by atomic force microscopy

International Nuclear Information System (INIS)

Qu Shuang; Chen Ying; Ge Shili; Liu Xiulin; Zhou Pingkun; Zhang Sa; Zhang Detian

2003-01-01

Objective: To find a new method for the measurement of radiation-induced damage, the structures of normal chromosomes and 60 Co γ-ray-induced chromosomal aberration were analyzed by atomic force microscopy. Methods: Normal and irradiated chromosomes of human peripheral blood lymphocytes were prepared, then three-dimensional structure and height of chromosomes were analyzed by atomic force microscopy. Results: Three-dimensional structures of normal chromosomes and dicentric aberration in irradiated chromosomes were observed clearly. The data of chromosome height were helpful to recognizing the dicentric aberrations. Conclusion: Atomic force microscopy providing three-dimension image and linear measurement is a new and valuable tool for structural analysis of radiation-induced chromosomal aberrations

Kelvin, thermodynamics and the natural world

CERN Document Server

Collins, MW; Koenig, C; Dougal, R C; Koenig, C; Ruddock, I

2015-01-01

This volume looks afresh at the life and works of Lord Kelvin including his standing and relationships with Charles Darwin, T. S Huxley and the X-club, thereby throwing new light on the nineteenth-century conflict between the British energy and biology specialists. Useful to scientists and engineers interested in thermodynamics and Lord Kelvin.

FEATURES OF MEASURING IN LIQUID MEDIA BY ATOMIC FORCE MICROSCOPY

Directory of Open Access Journals (Sweden)

Mikhail V. Zhukov

2016-11-01

Full Text Available Subject of Research.The paper presents results of experimental study of measurement features in liquids by atomic force microscope to identify the best modes and buffered media as well as to find possible image artifacts and ways of their elimination. Method. The atomic force microscope Ntegra Aura (NT-MDT, Russia with standard prism probe holder and liquid cell was used to carry out measurements in liquids. The calibration lattice TGQ1 (NT-MDT, Russia was chosen as investigated structure with a fixed shape and height. Main Results. The research of probe functioning in specific pH liquids (distilled water, PBS - sodium phosphate buffer, Na2HPO4 - borate buffer, NaOH 0.1 M, NaOH 0.5 M was carried out in contact and semi-contact modes. The optimal operating conditions and the best media for the liquid measurements were found. Comparison of atomic force microscopy data with the results of lattice study by scanning electron microscopy was performed. The features of the feedback system response in the «probe-surface» interaction were considered by the approach/retraction curves in the different environments. An artifact of image inversion was analyzed and recommendation for its elimination was provided. Practical Relevance. These studies reveal the possibility of fine alignment of research method for objects of organic and inorganic nature by atomic force microscopy in liquid media.

Kelvin-Helmholtz instability in solar spicules

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H Ebadi

2016-12-01

Full Text Available Magneto hydrodynamic waves, propagating along spicules, may become unstable and the expected instability is of Kelvin-Helmholtz type. Such instability can trigger the onset of wave turbulence leading to an effective plasma heating and particle acceleration. In present study, two-dimensional magneto hydrodynamic simulations performed on a Cartesian grid is presented in spicules with different densities, moving at various speeds depending on their environment. Simulations being applied in this study show the onset of Kelvin-Helmholtz type instability and transition to turbulent flow in spicules. Development of Kelvin-Helmholtz instability leads to momentum and energy transport, dissipation, and mixing of fluids. When magnetic fields are involved, field amplification is also possible to take place

Model-based traction force microscopy reveals differential tension in cellular actin bundles.

Science.gov (United States)

Soiné, Jérôme R D; Brand, Christoph A; Stricker, Jonathan; Oakes, Patrick W; Gardel, Margaret L; Schwarz, Ulrich S

2015-03-01

Adherent cells use forces at the cell-substrate interface to sense and respond to the physical properties of their environment. These cell forces can be measured with traction force microscopy which inverts the equations of elasticity theory to calculate them from the deformations of soft polymer substrates. We introduce a new type of traction force microscopy that in contrast to traditional methods uses additional image data for cytoskeleton and adhesion structures and a biophysical model to improve the robustness of the inverse procedure and abolishes the need for regularization. We use this method to demonstrate that ventral stress fibers of U2OS-cells are typically under higher mechanical tension than dorsal stress fibers or transverse arcs.

Ferritin protein imaging and detection by magnetic force microscopy.

Science.gov (United States)

Hsieh, Chiung-Wen; Zheng, Bin; Hsieh, Shuchen

2010-03-14

Magnetic force microscopy was used to image and detect ferritin proteins and the strength of the magnetic signal is discussed, revealing a large workable lift height between the magnetic tip and the ferritin sample.

Taking Nanomedicine Teaching into Practice with Atomic Force Microscopy and Force Spectroscopy

Science.gov (United States)

Carvalho, Filomena A.; Freitas, Teresa; Santos, Nuno C.

2015-01-01

Atomic force microscopy (AFM) is a useful and powerful tool to study molecular interactions applied to nanomedicine. The aim of the present study was to implement a hands-on atomic AFM course for graduated biosciences and medical students. The course comprises two distinct practical sessions, where students get in touch with the use of an atomic…

Force and Compliance Measurements on Living Cells Using Atomic Force Microscopy (AFM

Directory of Open Access Journals (Sweden)

Wojcikiewicz Ewa P.

2004-01-01

Full Text Available We describe the use of atomic force microscopy (AFM in studies of cell adhesion and cell compliance. Our studies use the interaction between leukocyte function associated antigen-1 (LFA-1/intercellular adhesion molecule-1 (ICAM-1 as a model system. The forces required to unbind a single LFA-1/ICAM-1 bond were measured at different loading rates. This data was used to determine the dynamic strength of the LFA-1/ICAM-1 complex and characterize the activation potential that this complex overcomes during its breakage. Force measurements acquired at the multiple- bond level provided insight about the mechanism of cell adhesion. In addition, the AFM was used as a microindenter to determine the mechanical properties of cells. The applications of these methods are described using data from a previous study.

Depletion interaction measured by colloidal probe atomic force microscopy

NARCIS (Netherlands)

Wijting, W.K.; Knoben, W.; Besseling, N.A.M.; Leermakers, F.A.M.; Cohen Stuart, M.A.

2004-01-01

We investigated the depletion interaction between stearylated silica surfaces in cyclohexane in the presence of dissolved polydimethylsiloxane by means of colloidal probe atomic force microscopy. We found that the range of the depletion interaction decreases with increasing concentration.

Cellulose fibril aggregation studies of eucalyptus dissolving pulps using atomic force microscopy

CSIR Research Space (South Africa)

Chunilall, Viren

2006-11-01

Full Text Available STUDIES OF Eucalyptus DISSOLVING PULPS USING ATOMIC FORCE MICROSCOPY V. Chunilall1, J.Wesley-Smith2, T. Bush1 1CSIR, Forestry and Forest Product Research Centre, P.O. Box 17001, Congella, 4013, South Africa. 2Electron Microscope Unit, University of Kwa... pulp using atomic force microscopy (AFM) have reported increased cellulose fibril aggregation during processing, and a concomitant decrease in surface area available for chemical reaction1,2. These findings were subsequently confirmed...

Kelvin Wave Influence on the Shallow-to-Deep Transition Over the Amazon

Science.gov (United States)

Rowe, A.; Serra, Y. L.

2017-12-01

over the Central Amazon in both global and regional model simulations with differing resolution and choice of convective parameterization. This work will test the hypothesis that when the environment is strongly modified by a Kelvin wave, model shallow-to-deep transition will be better simulated than when this forcing is not present.

A sub-Kelvin cryogen-free EPR system.

Science.gov (United States)

Melhuish, Simon J; Stott, Chloe; Ariciu, Ana-Maria; Martinis, Lorenzo; McCulloch, Mark; Piccirillo, Lucio; Collison, David; Tuna, Floriana; Winpenny, Richard

2017-09-01

We present an EPR instrument built for operation at Q band below 1K. Our cryogen-free Dewar integrates with a commercial electro-magnet and bridge. A description of the cryogenic and RF systems is given, along with the adaptations to the standard EPR experiment for operation at sub-Kelvin temperatures. As a first experiment, the EPR spectra of powdered Cr 12 O 9 (OH) 3 [Formula: see text] were measured. The sub-Kelvin EPR spectra agree well with predictions, and the performance of the sub-Kelvin system at 5K is compared to that of a commercial spectrometer. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

VEDA: a web-based virtual environment for dynamic atomic force microscopy.

Science.gov (United States)

Melcher, John; Hu, Shuiqing; Raman, Arvind

2008-06-01

We describe here the theory and applications of virtual environment dynamic atomic force microscopy (VEDA), a suite of state-of-the-art simulation tools deployed on nanoHUB (www.nanohub.org) for the accurate simulation of tip motion in dynamic atomic force microscopy (dAFM) over organic and inorganic samples. VEDA takes advantage of nanoHUB's cyberinfrastructure to run high-fidelity dAFM tip dynamics computations on local clusters and the teragrid. Consequently, these tools are freely accessible and the dAFM simulations are run using standard web-based browsers without requiring additional software. A wide range of issues in dAFM ranging from optimal probe choice, probe stability, and tip-sample interaction forces, power dissipation, to material property extraction and scanning dynamics over hetereogeneous samples can be addressed.

Atomic Force Microscopy Based Nanorobotics Modelling, Simulation, Setup Building and Experiments

CERN Document Server

Xie, Hui; Régnier, Stéphane; Sitti, Metin

2012-01-01

The atomic force microscope (AFM) has been successfully used to perform nanorobotic manipulation operations on nanoscale entities such as particles, nanotubes, nanowires, nanocrystals, and DNA since 1990s. There have been many progress on modeling, imaging, teleoperated or automated control, human-machine interfacing, instrumentation, and applications of AFM based nanorobotic manipulation systems in literature. This book aims to include all of such state-of-the-art progress in an organized, structured, and detailed manner as a reference book and also potentially a textbook in nanorobotics and any other nanoscale dynamics, systems and controls related research and education. Clearly written and well-organized, this text introduces designs and prototypes of the nanorobotic systems in detail with innovative principles of three-dimensional manipulation force microscopy and parallel imaging/manipulation force microscopy.

Quantitative 3D-KPFM imaging with simultaneous electrostatic force and force gradient detection

International Nuclear Information System (INIS)

Collins, L; Rodriguez, B J; Okatan, M B; Li, Q; Kravenchenko, I I; Lavrik, N V; Kalinin, S V; Jesse, S

2015-01-01

Kelvin probe force microscopy (KPFM) is a powerful characterization technique for imaging local electrochemical and electrostatic potential distributions and has been applied across a broad range of materials and devices. Proper interpretation of the local KPFM data can be complicated, however, by convolution of the true surface potential under the tip with additional contributions due to long range capacitive coupling between the probe (e.g. cantilever, cone, tip apex) and the sample under test. In this work, band excitation (BE)-KPFM is used to negate such effects. In contrast to traditional single frequency KPFM, multifrequency BE-KPFM is shown to afford dual sensitivity to both the electrostatic force and the force gradient detection, analogous to simultaneous amplitude modulated and frequency modulated KPFM imaging. BE-KPFM is demonstrated on a Pt/Au/SiO x test structure and electrostatic force gradient detection is found to lead to an improved lateral resolution compared to electrostatic force detection. Finally, a 3D-KPFM imaging technique is developed. Force volume (FV) BE-KPFM allows the tip–sample distance dependence of the electrostatic interactions (force and force gradient) to be recorded at each point across the sample surface. As such, FVBE-KPFM provides a much needed pathway towards complete tip–sample capacitive de-convolution in KPFM measurements and will enable quantitative surface potential measurements with nanoscale resolution. (paper)

Energy dissipation in multifrequency atomic force microscopy

Directory of Open Access Journals (Sweden)

Valentina Pukhova

2014-04-01

Full Text Available The instantaneous displacement, velocity and acceleration of a cantilever tip impacting onto a graphite surface are reconstructed. The total dissipated energy and the dissipated energy per cycle of each excited flexural mode during the tip interaction is retrieved. The tip dynamics evolution is studied by wavelet analysis techniques that have general relevance for multi-mode atomic force microscopy, in a regime where few cantilever oscillation cycles characterize the tip–sample interaction.

Atomic force microscopy of torus-bearing pit membranes

Science.gov (United States)

Roland R. Dute; Thomas Elder

2011-01-01

Atomic force microscopy was used to compare the structures of dried, torus-bearing pit membranes from four woody species, three angiosperms and one gymnosperm. Tori of Osmanthus armatus are bipartite consisting of a pustular zone overlying parallel sets of microfibrils that form a peripheral corona. Microfibrils of the corona form radial spokes as they traverse the...

High resolution magnetic force microscopy using focused ion beam modified tips

NARCIS (Netherlands)

Phillips, G.N.; Siekman, Martin Herman; Abelmann, Leon; Lodder, J.C.

2002-01-01

Atomic force microscope tips coated by the thermal evaporation of a magnetic 30 nm thick Co film have been modified by focused ion beam milling with Ga+ ions to produce tips suitable for magnetic force microscopy. Such tips possess a planar magnetic element with high magnetic shape anisotropy, an

Observation of multicellular spinning behavior of Proteus mirabilis by atomic force microscopy and multifunctional microscopy.

Science.gov (United States)

Liu, Yanxia; Deng, Yuanxin; Luo, Shuxiu; Deng, Yu; Guo, Linming; Xu, Weiwei; Liu, Lei; Liu, Junkang

2014-01-01

This study aimed to observe the multicellular spinning behavior of Proteus mirabilis by atomic force microscopy (AFM) and multifunctional microscopy in order to understand the mechanism underlying this spinning movement and its biological significance. Multifunctional microscopy with charge-coupled device (CCD) and real-time AFM showed changes in cell structure and shape of P. mirabilis during multicellular spinning movement. Specifically, the morphological characteristics of P. mirabilis, multicellular spinning dynamics, and unique movement were observed. Our findings indicate that the multicellular spinning behavior of P. mirabilis may be used to collect nutrients, perform colonization, and squeeze out competitors. The movement characteristics of P. mirabilis are vital to the organism's biological adaptability to the surrounding environment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Microscopy studies on pronton exchange membrane fuel cell electrodes with different ionomer contents

DEFF Research Database (Denmark)

Ma, Shuang; Solterbeck, Claus Henning; Odgaard, Madeleine

2009-01-01

of the electrode was well displayed in the topography and phase images. The particle and pore size (Z) distributions showed the most frequent values at 30-40 nm and 20-30 nm, respectively. The particle size corresponds to the size of the carbon support for the platinum catalyst. Catalyst agglomeration was observed......Proton Exchange Membrane (PEM) fuel cell electrodes with different ionomer contents were studied with various microscopic techniques. The morphology and surface potential were examined by Atomic Force Microscopy (AFM) and Kelvin Probe Microscopy (KPM), respectively. The particulate nature...... in high ionomer content electrodes. The surface potential images showed distinct difference to the topography images. The overall grain size was seen to increase, the pore volume to decrease, the surface roughness to decrease, and the surface potential variation to increase with the increase of ionomer...

Ultrasonic force microscopy: detection and imaging of ultra-thin molecular domains.

Science.gov (United States)

Dinelli, Franco; Albonetti, Cristiano; Kolosov, Oleg V

2011-03-01

The analysis of the formation of ultra-thin organic films is a very important issue. In fact, it is known that the properties of organic light emitting diodes and field effect transistors are strongly affected by the early growth stages. For instance, in the case of sexithiophene, the presence of domains made of molecules with the backbone parallel to the substrate surface has been indirectly evidenced by photoluminescence spectroscopy and confocal microscopy. On the contrary, conventional scanning force microscopy both in contact and intermittent contact modes have failed to detect such domains. In this paper, we show that Ultrasonic Force Microscopy (UFM), sensitive to nanomechanical properties, allows one to directly identify the structure of sub-monolayer thick films. Sexithiophene flat domains have been imaged for the first time with nanometer scale spatial resolution. A comparison with lateral force and intermittent contact modes has been carried out in order to explain the origins of the UFM contrast and its advantages. In particular, it indicates that UFM is highly suitable for investigations where high sensitivity to material properties, low specimen damage and high spatial resolution are required. Copyright © 2010 Elsevier B.V. All rights reserved.

Evidence of Boundary Reflection of Kelvin and First-Mode Rossby Waves from Topex/Poseidon Sea Level Data

Science.gov (United States)

Boulanger, Jean-Philippe; Fu, Lee-Lueng

1996-01-01

The TOPEX/POSEIDON sea level data lead to new opportunities to investigate some theoretical mechanisms suggested to be involved in the El Nino-Southern Oscillation phenomenon in the tropical Pacific ocean. In particular, we are interested in studying the western boundary reflection, a process crucial for the delayed action oscillator theory, by using the TOPEX/POSEIDON data from November 1992 to May 1995. We first projected the sea level data onto Kelvin and first-mode Ross waves. Then we estimated the contribution of wind forcing to these waves by using a single baroclinic mode simple wave model forced by the ERS-1 wind data. Wave propagation was clearly observed with amplitudes well explained by the wind forcing in the ocean interior. Evidence of wave reflection was detected at both the western and eastern boundaries of the tropical Pacific ocean. At the eastern boundary, Kelvin waves were seen to reflect as first-mode Rossby waves during the entire period. The reflection efficiency (in terms of wave amplitude) of the South American coasts was estimated to be 80% of that of an infinite meridional wall. At the western boundary, reflection was observed in April-August 1993, in January-June 1994, and, later, in December 1994 to February 1995. Although the general roles of these reflection events in the variability observed in the equatorial Pacific ocean are not clear, the data suggest that the reflections in January-June 1994 have played a role in the onset of the warm conditions observed in late 1994 to early 1995. Indeed, during the January-June 1994 period, as strong downwelling first-mode Rossby waves reflected into downwelling Kelvin waves, easterly wind and cold sea surface temperature anomalies located near the date line weakened and eventually reversed in June-July 1994. The presence of the warm anomalies near the date line then favored convection and westerly wind anomalies that triggered strong downwelling Kelvin waves propagating throughout the basin

Uncertainties in forces extracted from non-contact atomic force microscopy measurements by fitting of long-range background forces

Directory of Open Access Journals (Sweden)

Adam Sweetman

2014-04-01

Full Text Available In principle, non-contact atomic force microscopy (NC-AFM now readily allows for the measurement of forces with sub-nanonewton precision on the atomic scale. In practice, however, the extraction of the often desired ‘short-range’ force from the experimental observable (frequency shift is often far from trivial. In most cases there is a significant contribution to the total tip–sample force due to non-site-specific van der Waals and electrostatic forces. Typically, the contribution from these forces must be removed before the results of the experiment can be successfully interpreted, often by comparison to density functional theory calculations. In this paper we compare the ‘on-minus-off’ method for extracting site-specific forces to a commonly used extrapolation method modelling the long-range forces using a simple power law. By examining the behaviour of the fitting method in the case of two radically different interaction potentials we show that significant uncertainties in the final extracted forces may result from use of the extrapolation method.

Metal layer mask patterning by force microscopy lithography

International Nuclear Information System (INIS)

Filho, H.D. Fonseca; Mauricio, M.H.P.; Ponciano, C.R.; Prioli, R.

2004-01-01

The nano-lithography of a metallic surface in air by atomic force microscopy while operated in contact mode and equipped with a diamond tip is presented. The aluminum mask was prepared by thermal deposition on arsenic sulfide films. The analysis of the scratches performed by the tip on the metallic mask show that the depth of the lithographed pattern increases with the increase of the applied normal force. The scanning velocity is also shown to influence the AFM patterning process. As the scanning velocity increases, the scratch depth and width decreases. Nano-indentations performed with the diamond tip show that the plastically deformed surface increases with the increase of the duration of the applied force. The use of the nano-lithography method to create nano-structures is discussed

[Comparison of cell elasticity analysis methods based on atomic force microscopy indentation].

Science.gov (United States)

Wang, Zhe; Hao, Fengtao; Chen, Xiaohu; Yang, Zhouqi; Ding, Chong; Shang, Peng

2014-10-01

In order to investigate in greater detail the two methods based on Hertz model for analyzing force-distance curve obtained by atomic force microscopy, we acquired the force-distance curves of Hela and MCF-7 cells by atomic force microscopy (AFM) indentation in this study. After the determination of contact point, Young's modulus in different indentation depth were calculated with two analysis methods of "two point" and "slope fitting". The results showed that the Young's modulus of Hela cell was higher than that of MCF-7 cell,which is in accordance with the F-actin distribution of the two types of cell. We found that the Young's modulus of the cells was decreased with increasing indentation depth and the curve trends by "slope fitting". This indicated that the "slope fitting" method could reduce the error caused by the miscalculation of contact point. The purpose of this study was to provide a guidance for researcher to choose an appropriate method for analyzing AFM indentation force-distance curve.

Atomic force microscopy applied to study macromolecular content of embedded biological material

Energy Technology Data Exchange (ETDEWEB)

Matsko, Nadejda B. [Electron Microscopy Centre, Institute of Applied Physics, HPM C 15.1, ETH-Hoenggerberg, CH-8093, Zurich (Switzerland)]. E-mail: matsko@iap.phys.ethz.ch

2007-02-15

We demonstrate that atomic force microscopy represents a powerful tool for the estimation of structural preservation of biological samples embedded in epoxy resin, in terms of their macromolecular distribution and architecture. The comparison of atomic force microscopy (AFM) and transmission electron microscopy (TEM) images of a biosample (Caenorhabditis elegans) prepared following to different types of freeze-substitution protocols (conventional OsO{sub 4} fixation, epoxy fixation) led to the conclusion that high TEM stainability of the sample results from a low macromolecular density of the cellular matrix. We propose a novel procedure aimed to obtain AFM and TEM images of the same particular organelle, which strongly facilitates AFM image interpretation and reveals new ultrastructural aspects (mainly protein arrangement) of a biosample in addition to TEM data.

Imaging latex–carbon nanotube composites by subsurface electrostatic force microscopy

International Nuclear Information System (INIS)

Patel, Sajan; Petty, Clayton W.; Krafcik, Karen Lee

2016-01-01

Electrostatic modes of atomic force microscopy have shown to be non-destructive and relatively simple methods for imaging conductors embedded in insulating polymers. Here we use electrostatic force microscopy to image the dispersion of carbon nanotubes in a latex-based conductive composite, which brings forth features not observed in previously studied systems employing linear polymer films. A fixed-potential model of the probe-nanotube electrostatics is presented which in principle gives access to the conductive nanoparticle's depth and radius, and the polymer film dielectric constant. Comparing this model to the data results in nanotube depths that appear to be slightly above the film–air interface. Furthermore, this result suggests that water-mediated charge build-up at the film–air interface may be the source of electrostatic phase contrast in ambient conditions.

Nonlinear Dynamics of Cantilever-Sample Interactions in Atomic Force Microscopy

Science.gov (United States)

Cantrell, John H.; Cantrell, Sean A.

2010-01-01

The interaction of the cantilever tip of an atomic force microscope (AFM) with the sample surface is obtained by treating the cantilever and sample as independent systems coupled by a nonlinear force acting between the cantilever tip and a volume element of the sample surface. The volume element is subjected to a restoring force from the remainder of the sample that provides dynamical equilibrium for the combined systems. The model accounts for the positions on the cantilever of the cantilever tip, laser probe, and excitation force (if any) via a basis set of set of orthogonal functions that may be generalized to account for arbitrary cantilever shapes. The basis set is extended to include nonlinear cantilever modes. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a matrix iteration procedure. The effects of oscillatory excitation forces applied either to the cantilever or to the sample surface (or to both) are obtained from the solution set and applied to the to the assessment of phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) modalities. The influence of bistable cantilever modes of on AFM signal generation is discussed. The effects on the cantilever-sample surface dynamics of subsurface features embedded in the sample that are perturbed by surface-generated oscillatory excitation forces and carried to the cantilever via wave propagation are accounted by the Bolef-Miller propagating wave model. Expressions pertaining to signal generation and image contrast in A-AFM are obtained and applied to amplitude modulation (intermittent contact) atomic force microscopy and resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM). The influence of phase accumulation in A-AFM on image contrast is discussed, as is the effect of hard contact and maximum nonlinearity regimes of A-AFM operation.

Variations of Kelvin waves around the TTL region during the stratospheric sudden warming events in the Northern Hemisphere winter

Directory of Open Access Journals (Sweden)

Y. Jia

2016-03-01

Full Text Available Spatial and temporal variabilities of Kelvin waves during stratospheric sudden warming (SSW events are investigated by the ERA-Interim reanalysis data, and the results are validated by the COSMIC temperature data. A case study on an exceptionally large SSW event in 2009, and a composite analysis comprising 18 events from 1980 to 2013 are presented. During SSW events, the average temperature increases by 20 K in the polar stratosphere, while the temperature in the tropical stratosphere decreases by about 4 K. Kelvin wave with wave numbers 1 and 2, and periods 10–20 days, clearly appear around the tropical tropopause layer (TTL during SSWs. The Kelvin wave activity shows obvious coupling with the convection localized in the India Ocean and western Pacific (Indo-Pacific region. Detailed analysis suggests that the enhanced meridional circulation driven by the extratropical planetary wave forcing during SSW events leads to tropical upwelling, which further produces temperature decrease in the tropical stratosphere. The tropical upwelling and cooling consequently result in enhancement of convection in the equatorial region, which excites the strong Kelvin wave activity. In addition, we investigated the Kelvin wave acceleration to the eastward zonal wind anomalies in the equatorial stratosphere during SSW events. The composite analysis shows that the proportion of Kelvin wave contribution ranges from 5 to 35 % during SSWs, much larger than in the non-SSW mid-winters (less than 5 % in the stratosphere. However, the Kelvin wave alone is insufficient to drive the equatorial eastward zonal wind anomalies during the SSW events, which suggests that the effects of other types of equatorial waves may not be neglected.

Probing living bacterial adhesion by single cell force spectroscopy using atomic force microscopy

DEFF Research Database (Denmark)

Zeng, Guanghong; Ogaki, Ryosuke; Regina, Viduthalai R.

be considered. We have therefore developed a simple and versatile method to make single-cell bacterial probes for measuring single cell adhesion with atomic force microscopy (AFM).[1] A single-cell probe was readily made by picking up a bacterial cell from a glass surface using a tipless AFM cantilever coated...... random immobilization is obtained by submerging the cantilever in a bacterial suspension. The reported method provides a general platform for investigating single cell interactions of bacteria with different surfaces and other cells by AFM force spectroscopy, thus improving our understanding....... The strain-dependent susceptibility to bacterial colonization on conventional PLL-g-PEG illustrates how bacterial diversity challenges development of “universal” antifouling coatings, and AFM single-cell force spectroscopy was proven to be a powerful tool to provide insights into the molecular mechanisms...

Magnetohydrodynamic Kelvin-Helmholtz instability; Magnetohydrodynamische Kelvin-Helmholtz-Instabilitaet

Energy Technology Data Exchange (ETDEWEB)

Brett, Walter

2014-07-21

In the presented work the Kelvin-Helmholtz-Instability in magnetohydrodynamic flows is analyzed with the methods of Multiple Scales. The concerned fluids are incompressible or have a varying density perpendicular to the vortex sheet, which is taken into account using a Boussinesq-Approximation and constant Brunt-Vaeisaelae-Frequencies. The Multiple Scale Analysis leads to nonlinear evolution equations for the amplitude of the perturbations. Special solutions to these equations are presented and the effects of the magnetic fields are discussed.

Silicon Nano fabrication by Atomic Force Microscopy-Based Mechanical Processing

International Nuclear Information System (INIS)

Miyake, Sh.; Wang, M.; Kim, J.

2014-01-01

This paper reviews silicon nano fabrication processes using atomic force microscopy (AFM). In particular, it summarizes recent results obtained in our research group regarding AFM-based silicon nano fabrication through mechanochemical local oxidation by diamond tip sliding, as well as mechanical, electrical, and electromechanical processing using an electrically conductive diamond tip. Microscopic three-dimensional manufacturing mainly relies on etching, deposition, and lithography. Therefore, a special emphasis was placed on nano mechanical processes, mechanochemical reaction by potassium hydroxide solution etching, and mechanical and electrical approaches. Several important surface characterization techniques consisting of scanning tunneling microscopy and related techniques, such as scanning probe microscopy and AFM, were also discussed.

Atomic Force Microscopy for Soil Analysis

Science.gov (United States)

gazze, andrea; doerr, stefan; dudley, ed; hallin, ingrid; matthews, peter; quinn, gerry; van keulen, geertje; francis, lewis

2016-04-01

Atomic Force Microscopy (AFM) is a high-resolution surface-sensitive technique, which provides 3-dimensional topographical information and material properties of both stiff and soft samples in their natural environments. Traditionally AFM has been applied to samples with low roughness: hence its use for soil analysis has been very limited so far. Here we report the optimization settings required for a standardization of high-resolution and artefact-free analysis of natural soil with AFM: soil immobilization, AFM probe selection, artefact recognition and minimization. Beyond topography, AFM can be used in a spectroscopic mode to evaluate nanomechanical properties, such as soil viscosity, stiffness, and deformation. In this regards, Bruker PeakForce-Quantitative NanoMechanical (QNM) AFM provides a fast and convenient way to extract physical properties from AFM force curves in real-time to obtain soil nanomechanical properties. Here we show for the first time the ability of AFM to describe the topography of natural soil at nanometre resolution, with observation of micro-components, such as clays, and of nano-structures, possibly of biotic origin, the visualization of which would prove difficult with other instrumentations. Finally, nanomechanical profiling has been applied to different wettability states in soil and the respective physical patterns are discussed.

Electrowetting Using a Microfluidic Kelvin Water Dropper

Directory of Open Access Journals (Sweden)

Elias Yazdanshenas

2018-02-01

Full Text Available The Kelvin water dropper is an electrostatic generator that can generate high voltage electricity through water dripping. A conventional Kelvin water dropper converts the gravitational potential energy of water into electricity. Due to its low current output, Kelvin water droppers can only be used in limited cases that demand high voltage. In the present study, microfluidic Kelvin water droppers (MKWDs were built in house to demonstrate a low-cost but accurately controlled miniature device for high voltage generation. The performance of the MKWDs was characterized using different channel diameters and flow rates. The best performed MKWD was then used to conduct experiments of the electrowetting of liquid on dielectric surfaces. Electrowetting is a process that has been widely used in manipulating the wetting properties of a surface using an external electric field. Usually electrowetting requires an expensive DC power supply that outputs high voltage. However, in this research, it was demonstrated that electrowetting can be conducted by simply using an MKWD. Additionally, an analytic model was developed to simulate the electrowetting process. Finally, the model’s ability to well predict the liquid deformation during electrowetting using MKWDs was validated.

Friction force microscopy study of annealed diamond-like carbon film

International Nuclear Information System (INIS)

Choi, Won Seok; Joung, Yeun-Ho; Heo, Jinhee; Hong, Byungyou

2012-01-01

In this paper we introduce mechanical and structural characteristics of diamond-like carbon (DLC) films which were prepared on silicon substrates by radio frequency (RF) plasma enhanced chemical vapor deposition (PECVD) method using methane (CH 4 ) and hydrogen (H 2 ) gas. The films were annealed at various temperatures ranging from 300 to 900 °C in steps of 200 °C using rapid thermal processor (RTP) in nitrogen ambient. Tribological properties of the DLC films were investigated by atomic force microscopy (AFM) in friction force microscopy (FFM) mode. The structural properties of the films were obtained by high resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The wettability of the films was obtained using contact angle measurement. XPS analysis showed that the sp 3 content is decreased from 75.2% to 24.1% while the sp 2 content is increased from 24.8% to 75.9% when the temperature is changed from 300 to 900 °C. The contact angles of DLC films were higher than 70°. The FFM measurement results show that the highest friction coefficient value was achieved at 900 °C annealing temperature.

Friction force microscopy study of annealed diamond-like carbon film

Energy Technology Data Exchange (ETDEWEB)

Choi, Won Seok; Joung, Yeun-Ho [School of Electrical Engineering, Hanbat National University, Daejeon 305-719 (Korea, Republic of); Heo, Jinhee [Materials Safety Evaluation Group, Korea Institute of Materials Science, Changwon 641-831 (Korea, Republic of); Hong, Byungyou, E-mail: byhong@skku.edu [School of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2012-10-15

In this paper we introduce mechanical and structural characteristics of diamond-like carbon (DLC) films which were prepared on silicon substrates by radio frequency (RF) plasma enhanced chemical vapor deposition (PECVD) method using methane (CH{sub 4}) and hydrogen (H{sub 2}) gas. The films were annealed at various temperatures ranging from 300 to 900 °C in steps of 200 °C using rapid thermal processor (RTP) in nitrogen ambient. Tribological properties of the DLC films were investigated by atomic force microscopy (AFM) in friction force microscopy (FFM) mode. The structural properties of the films were obtained by high resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The wettability of the films was obtained using contact angle measurement. XPS analysis showed that the sp{sup 3} content is decreased from 75.2% to 24.1% while the sp{sup 2} content is increased from 24.8% to 75.9% when the temperature is changed from 300 to 900 °C. The contact angles of DLC films were higher than 70°. The FFM measurement results show that the highest friction coefficient value was achieved at 900 °C annealing temperature.

Imaging three-dimensional surface objects with submolecular resolution by atomic force microscopy

Czech Academy of Sciences Publication Activity Database

Moreno, C.; Stetsovych, Oleksandr; Shimizu, T.K.; Custance, O.

2015-01-01

Roč. 15, č. 4 (2015), s. 2257-2262 ISSN 1530-6984 Institutional support: RVO:68378271 Keywords : noncontact atomic force microscopy (NC- AFM ) * submolecular resolution * three-dimensional dynamic force spectroscopy * high-resolution imaging Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 13.779, year: 2015

Atomic force microscopy of starch systems.

Science.gov (United States)

Zhu, Fan

2017-09-22

Atomic force microscopy (AFM) generates information on topography, adhesion, and elasticity of sample surface by touching with a tip. Under suitable experimental settings, AFM can image biopolymers of few nanometers. Starch is a major food and industrial component. AFM has been used to probe the morphology, properties, modifications, and interactions of starches from diverse botanical origins at both micro- and nano-structural levels. The structural information obtained by AFM supports the blocklet structure of the granules, and provides qualitative and quantitative basis for some physicochemical properties of diverse starch systems. It becomes evident that AFM can complement other microscopic techniques to provide novel structural insights for starch systems.

Studying the Adhesion Force and Glass Transition of Thin Polystyrene Films by Atomic Force Microscopy

DEFF Research Database (Denmark)

Kang, Hua; Qian, Xiaoqin; Guan, Li

2018-01-01

microscopy (AFM)-based forcedistance curve to study the relaxation dynamics and the film thickness dependence of glass transition temperature (T-g) for normal thin polystyrene (PS) films supported on silicon substrate. The adhesion force (F-ad) between AFM tip and normal thin PS film surfaces...

Stacking it up: Exploring the limits of ultra-high resolution atomic force microscopy

NARCIS (Netherlands)

van der Heijden, N.J.

2017-01-01

Atomic force microscopy (AFM) is a technique wherein an atomically sharp needle raster scans across a surface, detecting forces between it and the sample. In state-of-the-art AFM experiments the measured forces are typically on the order of pico-Newtons, and the lateral resolution is on the order of

Atomic force and scanning near-field optical microscopy study of carbocyanine dye J-aggregates

Czech Academy of Sciences Publication Activity Database

Prokhorov, V.V.; Petrova, M.G.; Kovaleva, Natalia; Demikhov, E.I.

2014-01-01

Roč. 10, č. 5 (2014), s. 700-704 ISSN 1573-4137 Institutional support: RVO:68378271 Keywords : carbocyanine dye * elementary fibri * high-resolution atomic force microscopy * J-aggregate * probe microscopy * scanning near-field optical microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.096, year: 2014

Electrostatic characteristics of nanostructures investigated using electric force microscopy

International Nuclear Information System (INIS)

Qiu, X.H.; Qi, G.C.; Yang, Y.L.; Wang, C.

2008-01-01

Nanosized materials possess many interesting physical and chemical properties that differ significantly from their macroscopic counterparts. Understanding the size- and shape-dependent properties of nanostructures are of great value to rational design of nanomaterials with desired functionality. Electric force microscopy (EFM) and its variations offer unique opportunities to deepen our insights into the electrical characteristics of nanostructures. In this paper, we review recent progress of this versatile technique and its applications in studying the electrical properties of nanosized materials. A variety of important issues in EFM experimentation and theoretical modeling are discussed, with an emphasis on the ongoing efforts to improve the precision in quantitative measurements of charge density and dielectric properties of nanostructures. - Graphical abstract: We review recent progress of electric force microscopy (EFM) and its applications in studying the electrical properties of nanostructures. A variety of important issues in EFM experimentation and theoretical modeling are discussed, with an emphasis on the ongoing efforts to improve the precision in quantitative measurements of charge density and dielectric properties of nanostructures

Kelvin and industry in Ireland

Science.gov (United States)

Crossland, Bernard; Whitaker, Andrew

2009-04-01

Kelvin was a great mathematician, theoretical and experimental physicist, and educator, founding the first physical laboratory. He worked tirelessly for the creation of a reproducible set of physical units, and he was also an experienced and enthusiastic sailor. All these talents were linked to his extensive technological work, of which the most important examples were the laying of the Atlantic cable, and the marine compass. In Ireland his most important contributions were the occulting nature of the Holywood lighthouse, and his connection with the Giant's Causeway tramway. Kelvin's work on cabling and national maritime projects may have stimulated his later strong support of the British Empire and opposition to Home Rule in Ireland.

Kelvin and industry in Ireland

Energy Technology Data Exchange (ETDEWEB)

Crossland, Bernard [Department of Mechanical Engineering, Queen' s University, Belfast BT7 1NN, Northern Ireland (United Kingdom); Whitaker, Andrew, E-mail: b.crossland@qub.ac.u, E-mail: a.whitaker@qub.ac.u [Department of Physics, Queen' s University, Belfast BT7 1NN, Northern Ireland (United Kingdom)

2009-04-01

Kelvin was a great mathematician, theoretical and experimental physicist, and educator, founding the first physical laboratory. He worked tirelessly for the creation of a reproducible set of physical units, and he was also an experienced and enthusiastic sailor. All these talents were linked to his extensive technological work, of which the most important examples were the laying of the Atlantic cable, and the marine compass. In Ireland his most important contributions were the occulting nature of the Holywood lighthouse, and his connection with the Giant's Causeway tramway. Kelvin's work on cabling and national maritime projects may have stimulated his later strong support of the British Empire and opposition to Home Rule in Ireland.

Kelvin and industry in Ireland

International Nuclear Information System (INIS)

Crossland, Bernard; Whitaker, Andrew

2009-01-01

Kelvin was a great mathematician, theoretical and experimental physicist, and educator, founding the first physical laboratory. He worked tirelessly for the creation of a reproducible set of physical units, and he was also an experienced and enthusiastic sailor. All these talents were linked to his extensive technological work, of which the most important examples were the laying of the Atlantic cable, and the marine compass. In Ireland his most important contributions were the occulting nature of the Holywood lighthouse, and his connection with the Giant's Causeway tramway. Kelvin's work on cabling and national maritime projects may have stimulated his later strong support of the British Empire and opposition to Home Rule in Ireland.

Imaging and manipulation of single viruses by atomic force microscopy

NARCIS (Netherlands)

Baclayon, M.; Wuite, G. J. L.; Roos, W. H.

2010-01-01

The recent developments in virus research and the application of functional viral particles in nanotechnology and medicine rely on sophisticated imaging and manipulation techniques at nanometre resolution in liquid, air and vacuum. Atomic force microscopy (AFM) is a tool that combines these

Sub-Angstrom oscillation amplitude non-contact atomic force microscopy for lateral force gradient measurement

International Nuclear Information System (INIS)

Atabak, Mehrdad; Unverdi, Ozhan; Ozer, H. Ozguer; Oral, Ahmet

2009-01-01

We report the first results from novel sub-Angstrom oscillation amplitude non-contact atomic force microscopy developed for lateral force gradient measurements. Quantitative lateral force gradients between a tungsten tip and Si(1 1 1)-(7 x 7) surface can be measured using this microscope. Simultaneous lateral force gradient and scanning tunnelling microscope images of single and multi atomic steps are obtained. In our measurement, tunnel current is used as feedback. The lateral stiffness contrast has been observed to be 2.5 N/m at single atomic step, in contrast to 13 N/m at multi atomic step on Si(1 1 1) surface. We also carried out a series of lateral stiffness-distance spectroscopy. We observed lateral stiffness-distance curves exhibit sharp increase in the stiffness as the sample is approached towards the surface. We usually observed positive stiffness and sometimes going into slightly negative region.

Force microscopy of layering and friction in an ionic liquid

International Nuclear Information System (INIS)

Hoth, Judith; Hausen, Florian; Bennewitz, Roland; Müser, Martin H

2014-01-01

The mechanical properties of the ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate ([Py 1,4 ][FAP]) in confinement between a SiO x and a Au(1 1 1) surface are investigated by means of atomic force microscopy (AFM) under electrochemical control. Up to 12 layers of ion pairs can be detected through force measurements while approaching the tip of the AFM to the surface. The particular shape of the force versus distance curve is explained by a model for the interaction between tip, gold surface and ionic liquid, which assumes an exponentially decaying oscillatory force originating from bulk liquid density correlations. Jumps in the tip–sample distance upon approach correspond to jumps of the compliant force sensor between branches of the oscillatory force curve. Frictional force between the laterally moving tip and the surface is detected only after partial penetration of the last double layer between tip and surface. (paper)

The effects of atomic force microscopy upon nominated living cells

Energy Technology Data Exchange (ETDEWEB)

O' Hagan, Barry Michael Gerard [School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, County Londonderry, BT52 1SA (United Kingdom)]. E-mail: bmg.ohagan@ulstser.ac.uk; Doyle, Peter [Unilever Research, Port Sunlight, The Wirral, Merseyside (United Kingdom); Allen, James M. [School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, County Londonderry, BT52 1SA (United Kingdom); Sutton, Kerry [School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, County Londonderry, BT52 1SA (United Kingdom); McKerr, George [School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, County Londonderry, BT52 1SA (United Kingdom)

2004-12-15

This work describes a system for precise re-location of cells within a monolayer after atomic force imaging. As we know little about probe interaction with soft biological surfaces any corroborative evidence is of great importance. For example, it is of paramount importance in living cell force microscopy that interrogated cells can be re-located and imaged by other corroborative technologies. Methodologies expressed here have shown that non-invasive force parameters can be established for specific cell types. Additionally, we show that the same sample can be transferred reliably to an SEM. Results here indicate that further work with live cells should initially establish appropriate prevailing force parameters and that cell damage should be checked for before and after an imaging experiment.

The effects of atomic force microscopy upon nominated living cells

International Nuclear Information System (INIS)

O'Hagan, Barry Michael Gerard; Doyle, Peter; Allen, James M.; Sutton, Kerry; McKerr, George

2004-01-01

This work describes a system for precise re-location of cells within a monolayer after atomic force imaging. As we know little about probe interaction with soft biological surfaces any corroborative evidence is of great importance. For example, it is of paramount importance in living cell force microscopy that interrogated cells can be re-located and imaged by other corroborative technologies. Methodologies expressed here have shown that non-invasive force parameters can be established for specific cell types. Additionally, we show that the same sample can be transferred reliably to an SEM. Results here indicate that further work with live cells should initially establish appropriate prevailing force parameters and that cell damage should be checked for before and after an imaging experiment

Observation of self-assembled fluorescent beads by scanning near-field optical microscopy and atomic force microscopy

International Nuclear Information System (INIS)

Oh, Y.J.; Jo, W.; Kim, Min-Gon; Kyu Park, Hyun; Hyun Chung, Bong

2006-01-01

Optical response and topography of fluorescent latex beads both on flat self-assembled monolayer and on a micron-patterned surface with poly(dimethylsiloxane) are studied. Scanning near-field optical microscopy and atomic force microscopy were utilized together for detecting fluorescence and imaging topography of the patterned latex beads, respectively. As a result, the micro-patterned latex beads where a specific chemical binding occurred show a strong signal, whereas no signals are observed in the case of nonspecific binding. With fluorescein isothiocyanate (FITC), it is convenient to measure fluorescence signal from the patterned beads allowing us to monitor the small balls of fluorescent latex

A dark mode in scanning thermal microscopy

Science.gov (United States)

Ramiandrisoa, Liana; Allard, Alexandre; Joumani, Youssef; Hay, Bruno; Gomés, Séverine

2017-12-01

The need for high lateral spatial resolution in thermal science using Scanning Thermal Microscopy (SThM) has pushed researchers to look for more and more tiny probes. SThM probes have consequently become more and more sensitive to the size effects that occur within the probe, the sample, and their interaction. Reducing the tip furthermore induces very small heat flux exchanged between the probe and the sample. The measurement of this flux, which is exploited to characterize the sample thermal properties, requires then an accurate thermal management of the probe-sample system and to reduce any phenomenon parasitic to this system. Classical experimental methodologies must then be constantly questioned to hope for relevant and interpretable results. In this paper, we demonstrate and estimate the influence of the laser of the optical force detection system used in the common SThM setup that is based on atomic-force microscopy equipment on SThM measurements. We highlight the bias induced by the overheating due to the laser illumination on the measurements performed by thermoresistive probes (palladium probe from Kelvin Nanotechnology). To face this issue, we propose a new experimental procedure based on a metrological approach of the measurement: a SThM "dark mode." The comparison with the classical procedure using the laser shows that errors between 14% and 37% can be reached on the experimental data exploited to determine the heat flux transferred from the hot probe to the sample.

High-frequency multimodal atomic force microscopy

Directory of Open Access Journals (Sweden)

Adrian P. Nievergelt

2014-12-01

Full Text Available Multifrequency atomic force microscopy imaging has been recently demonstrated as a powerful technique for quickly obtaining information about the mechanical properties of a sample. Combining this development with recent gains in imaging speed through small cantilevers holds the promise of a convenient, high-speed method for obtaining nanoscale topography as well as mechanical properties. Nevertheless, instrument bandwidth limitations on cantilever excitation and readout have restricted the ability of multifrequency techniques to fully benefit from small cantilevers. We present an approach for cantilever excitation and deflection readout with a bandwidth of 20 MHz, enabling multifrequency techniques extended beyond 2 MHz for obtaining materials contrast in liquid and air, as well as soft imaging of delicate biological samples.

A novel self-sensing technique for tapping-mode atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Ruppert, Michael G.; Moheimani, S. O. Reza [The University of Newcastle, University Drive, Callaghan NSW 2308 (Australia)

2013-12-15

This work proposes a novel self-sensing tapping-mode atomic force microscopy operation utilizing charge measurement. A microcantilever coated with a single piezoelectric layer is simultaneously used for actuation and deflection sensing. The cantilever can be batch fabricated with existing micro electro mechanical system processes. The setup enables the omission of the optical beam deflection technique which is commonly used to measure the cantilever oscillation amplitude. Due to the high amount of capacitive feedthrough in the measured charge signal, a feedforward control technique is employed to increase the dynamic range from less than 1 dB to approximately 35 dB. Experiments show that the conditioned charge signal achieves excellent signal-to-noise ratio and can therefore be used as a feedback signal for atomic force microscopy imaging.

Electrostatic force microscopy: imaging DNA and protein polarizations one by one

International Nuclear Information System (INIS)

Mikamo-Satoh, Eriko; Yamada, Fumihiko; Takagi, Akihiko; Matsumoto, Takuya; Kawai, Tomoji

2009-01-01

We present electrostatic force microscopy images of double-stranded DNA and transcription complex on an insulating mica substrate obtained with molecular resolution using a frequency-mode noncontact atomic force microscope. The electrostatic potential images show that both DNA and transcription complexes are polarized with an upward dipole moment. Potential differences of these molecules from the mica substrate enabled us to estimate dipole moments of isolated DNA and transcription complex in zero external field to be 0.027 D/base and 0.16 D/molecule, respectively. Scanning capacitance microscopy demonstrates characteristic contrast inversion between DNA and transcription complex images, indicating the difference in electric polarizability of these molecules. These findings indicate that the electrostatic properties of individual biological molecules can be imaged on an insulator substrate while retaining complex formation.

Imaging of RNA in situ hybridization by atomic force microscopy

NARCIS (Netherlands)

Kalle, W.H.J.; Macville, M.V.E.; van de Corput, M.P.C.; de Grooth, B.G.; Tanke, H.J.; Raap, A.K.

In this study we investigated the possibility of imaging internal cellular molecules after cytochemical detection with atomic force microscopy (AFM). To this end, rat 9G and HeLa cells were hybridized with haptenized probes for 28S ribosomal RNA, human elongation factor mRNA and cytomegalovirus

Effectiveness of Modal Decomposition for Tapping Atomic Force Microscopy Microcantilevers in Liquid Environment.

Science.gov (United States)

Kim, Il Kwang; Lee, Soo Il

2016-05-01

The modal decomposition of tapping mode atomic force microscopy microcantilevers in liquid environments was studied experimentally. Microcantilevers with different lengths and stiffnesses and two sample surfaces with different elastic moduli were used in the experiment. The response modes of the microcantilevers were extracted as proper orthogonal modes through proper orthogonal decomposition. Smooth orthogonal decomposition was used to estimate the resonance frequency directly. The effects of the tapping setpoint and the elastic modulus of the sample under test were examined in terms of their multi-mode responses with proper orthogonal modes, proper orthogonal values, smooth orthogonal modes and smooth orthogonal values. Regardless of the stiffness of the microcantilever under test, the first mode was dominant in tapping mode atomic force microscopy under normal operating conditions. However, at lower tapping setpoints, the flexible microcantilever showed modal distortion and noise near the tip when tapping on a hard sample. The stiff microcantilever had a higher mode effect on a soft sample at lower tapping setpoints. Modal decomposition for tapping mode atomic force microscopy can thus be used to estimate the characteristics of samples in liquid environments.

Role of interannual Kelvin wave propagations in the equatorial Atlantic on the Angola Benguela Current system

Science.gov (United States)

Imbol Koungue, Rodrigue Anicet; Illig, Serena; Rouault, Mathieu

2017-06-01

The link between equatorial Atlantic Ocean variability and the coastal region of Angola-Namibia is investigated at interannual time scales from 1998 to 2012. An index of equatorial Kelvin wave activity is defined based on Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). Along the equator, results show a significant correlation between interannual PIRATA monthly dynamic height anomalies, altimetric monthly Sea Surface Height Anomalies (SSHA), and SSHA calculated with an Ocean Linear Model. This allows us to interpret PIRATA records in terms of equatorial Kelvin waves. Estimated phase speed of eastward propagations from PIRATA equatorial mooring remains in agreement with the linear theory, emphasizing the dominance of the second baroclinic mode. Systematic analysis of all strong interannual equatorial SSHA shows that they precede by 1-2 months extreme interannual Sea Surface Temperature Anomalies along the African coast, which confirms the hypothesis that major warm and cold events in the Angola-Benguela current system are remotely forced by ocean atmosphere interactions in the equatorial Atlantic. Equatorial wave dynamics is at the origin of their developments. Wind anomalies in the Western Equatorial Atlantic force equatorial downwelling and upwelling Kelvin waves that propagate eastward along the equator and then poleward along the African coast triggering extreme warm and cold events, respectively. A proxy index based on linear ocean dynamics appears to be significantly more correlated with coastal variability than an index based on wind variability. Results show a seasonal phasing, with significantly higher correlations between our equatorial index and coastal SSTA in October-April season.

Some image artefacts in non-contact mode force microscopy

International Nuclear Information System (INIS)

Dinte, B.P.; Watson, G.S.; Dobson, J.F.; Myhra, S.

1996-01-01

Full text: Non-contact mode Atomic Force Microscopy (AFM), performed in air, of two-dimensional hexagonal close-packed (2DHCP) layers of 200 nm diameter polystyrene spheres yields images containing artefacts ('ghost spheres') at layer edges and vacancy sites. The origin of these artefacts is clearly not the simple convolution of the tip and sample geometries, but must be the interaction between them. A computer program was written to simulate the experimental contours, assuming that the only force between the tip and the sample is the van der Waals (dispersion) force, and that the contours traced by the AFM tip are those of constant force derivative. The energy was calculated by integrating R -6 over the volumes of the tip and the sample, with a (constant) arbitrary scaling factor. The experimental contours were reproduced by the simulations, except for the 'ghost' artefacts. The assumption that there is only a dispersion force is thus incorrect. The experiments were performed in air, so that all surfaces were coated by a layer of adsorbed moisture. It is proposed that meniscus forces may be the origin of the artefacts

Application of atomic force microscopy to the study of natural and model soil particles.

Science.gov (United States)

Cheng, S; Bryant, R; Doerr, S H; Rhodri Williams, P; Wright, C J

2008-09-01

The structure and surface chemistry of soil particles has extensive impact on many bulk scale properties and processes of soil systems and consequently the environments that they support. There are a number of physiochemical mechanisms that operate at the nanoscale which affect the soil's capability to maintain native vegetation and crops; this includes soil hydrophobicity and the soil's capacity to hold water and nutrients. The present study used atomic force microscopy in a novel approach to provide unique insight into the nanoscale properties of natural soil particles that control the physiochemical interaction of material within the soil column. There have been few atomic force microscopy studies of soil, perhaps a reflection of the heterogeneous nature of the system. The present study adopted an imaging and force measurement research strategy that accounted for the heterogeneity and used model systems to aid interpretation. The surface roughness of natural soil particles increased with depth in the soil column a consequence of the attachment of organic material within the crevices of the soil particles. The roughness root mean square calculated from ten 25 microm(2) images for five different soil particles from a Netherlands soil was 53.0 nm, 68.0 nm, 92.2 nm and 106.4 nm for the respective soil depths of 0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm. A novel analysis method of atomic force microscopy phase images based on phase angle distribution across a surface was used to interpret the nanoscale distribution of organic material attached to natural and model soil particles. Phase angle distributions obtained from phase images of model surfaces were found to be bimodal, indicating multiple layers of material, which changed with the concentration of adsorbed humic acid. Phase angle distributions obtained from phase images of natural soil particles indicated a trend of decreasing surface coverage with increasing depth in the soil column. This was consistent with

Simple test system for single molecule recognition force microscopy

International Nuclear Information System (INIS)

Riener, Christian K.; Stroh, Cordula M.; Ebner, Andreas; Klampfl, Christian; Gall, Alex A.; Romanin, Christoph; Lyubchenko, Yuri L.; Hinterdorfer, Peter; Gruber, Hermann J.

2003-01-01

We have established an easy-to-use test system for detecting receptor-ligand interactions on the single molecule level using atomic force microscopy (AFM). For this, avidin-biotin, probably the best characterized receptor-ligand pair, was chosen. AFM sensors were prepared containing tethered biotin molecules at sufficiently low surface concentrations appropriate for single molecule studies. A biotin tether, consisting of a 6 nm poly(ethylene glycol) (PEG) chain and a functional succinimide group at the other end, was newly synthesized and covalently coupled to amine-functionalized AFM tips. In particular, PEG 800 diamine was glutarylated, the mono-adduct NH 2 -PEG-COOH was isolated by ion exchange chromatography and reacted with biotin succinimidylester to give biotin-PEG-COOH which was then activated as N-hydroxysuccinimide (NHS) ester to give the biotin-PEG-NHS conjugate which was coupled to the aminofunctionalized AFM tip. The motional freedom provided by PEG allows for free rotation of the biotin molecule on the AFM sensor and for specific binding to avidin which had been adsorbed to mica surfaces via electrostatic interactions. Specific avidin-biotin recognition events were discriminated from nonspecific tip-mica adhesion by their typical unbinding force (∼40 pN at 1.4 nN/s loading rate), unbinding length (<13 nm), the characteristic nonlinear force-distance relation of the PEG linker, and by specific block with excess of free d-biotin. The convenience of the test system allowed to evaluate, and compare, different methods and conditions of tip aminofunctionalization with respect to specific binding and nonspecific adhesion. It is concluded that this system is well suited as calibration or start-up kit for single molecule recognition force microscopy

Taking nanomedicine teaching into practice with atomic force microscopy and force spectroscopy.

Science.gov (United States)

Carvalho, Filomena A; Freitas, Teresa; Santos, Nuno C

2015-12-01

Atomic force microscopy (AFM) is a useful and powerful tool to study molecular interactions applied to nanomedicine. The aim of the present study was to implement a hands-on atomic AFM course for graduated biosciences and medical students. The course comprises two distinct practical sessions, where students get in touch with the use of an atomic force microscope by performing AFM scanning images of human blood cells and force spectroscopy measurements of the fibrinogen-platelet interaction. Since the beginning of this course, in 2008, the overall rating by the students was 4.7 (out of 5), meaning a good to excellent evaluation. Students were very enthusiastic and produced high-quality AFM images and force spectroscopy data. The implementation of the hands-on AFM course was a success, giving to the students the opportunity of contact with a technique that has a wide variety of applications on the nanomedicine field. In the near future, nanomedicine will have remarkable implications in medicine regarding the definition, diagnosis, and treatment of different diseases. AFM enables students to observe single molecule interactions, enabling the understanding of molecular mechanisms of different physiological and pathological processes at the nanoscale level. Therefore, the introduction of nanomedicine courses in bioscience and medical school curricula is essential. Copyright © 2015 The American Physiological Society.

Microcontroller-driven fluid-injection system for atomic force microscopy.

Science.gov (United States)

Kasas, S; Alonso, L; Jacquet, P; Adamcik, J; Haeberli, C; Dietler, G

2010-01-01

We present a programmable microcontroller-driven injection system for the exchange of imaging medium during atomic force microscopy. Using this low-noise system, high-resolution imaging can be performed during this process of injection without disturbance. This latter circumstance was exemplified by the online imaging of conformational changes in DNA molecules during the injection of anticancer drug into the fluid chamber.

Use of atomic force microscopy and transmission electron microscopy for correlative studies of bacterial capsules.

Science.gov (United States)

Stukalov, Oleg; Korenevsky, Anton; Beveridge, Terry J; Dutcher, John R

2008-09-01

Bacteria can possess an outermost assembly of polysaccharide molecules, a capsule, which is attached to their cell wall. We have used two complementary, high-resolution microscopy techniques, atomic force microscopy (AFM) and transmission electron microscopy (TEM), to study bacterial capsules of four different gram-negative bacterial strains: Escherichia coli K30, Pseudomonas aeruginosa FRD1, Shewanella oneidensis MR-4, and Geobacter sulfurreducens PCA. TEM analysis of bacterial cells using different preparative techniques (whole-cell mounts, conventional embeddings, and freeze-substitution) revealed capsules for some but not all of the strains. In contrast, the use of AFM allowed the unambiguous identification of the presence of capsules on all strains used in the present study, including those that were shown by TEM to be not encapsulated. In addition, the use of AFM phase imaging allowed the visualization of the bacterial cell within the capsule, with a depth sensitivity that decreased with increasing tapping frequency.

Reconstruction of Undersampled Atomic Force Microscopy Images

DEFF Research Database (Denmark)

Jensen, Tobias Lindstrøm; Arildsen, Thomas; Østergaard, Jan

2013-01-01

Atomic force microscopy (AFM) is one of the most advanced tools for high-resolution imaging and manipulation of nanoscale matter. Unfortunately, standard AFM imaging requires a timescale on the order of seconds to minutes to acquire an image which makes it complicated to observe dynamic processes....... Moreover, it is often required to take several images before a relevant observation region is identified. In this paper we show how to significantly reduce the image acquisition time by undersampling. The reconstruction of an undersampled AFM image can be viewed as an inpainting, interpolating problem...... should be reconstructed using interpolation....

Invited Article: VEDA: A web-based virtual environment for dynamic atomic force microscopy

Science.gov (United States)

Melcher, John; Hu, Shuiqing; Raman, Arvind

2008-06-01

We describe here the theory and applications of virtual environment dynamic atomic force microscopy (VEDA), a suite of state-of-the-art simulation tools deployed on nanoHUB (www.nanohub.org) for the accurate simulation of tip motion in dynamic atomic force microscopy (dAFM) over organic and inorganic samples. VEDA takes advantage of nanoHUB's cyberinfrastructure to run high-fidelity dAFM tip dynamics computations on local clusters and the teragrid. Consequently, these tools are freely accessible and the dAFM simulations are run using standard web-based browsers without requiring additional software. A wide range of issues in dAFM ranging from optimal probe choice, probe stability, and tip-sample interaction forces, power dissipation, to material property extraction and scanning dynamics over hetereogeneous samples can be addressed.

INVESTIGATION OF POLYMER SURFACES USING SCANNING FORCE MICROSCOPY (SFM) - A NEW DIRECT LOOK ON OLD POLYMER PROBLEMS

NARCIS (Netherlands)

GRIM, PCM; BROUWER, HJ; SEYGER, RM; OOSTERGETEL, GT; BERGSMASCHUTTER, WG; ARNBERG, AC; GUTHNER, P; DRANSFELD, K; HADZIIOANNOU, G

In this contribution, the general concepts of force microscopy will be presented together with its application to polymer surfaces (Ref.1). Several examples will be presented to illustrate that force microscopy is a powerful and promising tool for investigation of (polymer) surfaces, such as the

Single molecule atomic force microscopy and force spectroscopy of chitosan.

Science.gov (United States)

Kocun, Marta; Grandbois, Michel; Cuccia, Louis A

2011-02-01

Atomic force microscopy (AFM) and AFM-based force spectroscopy was used to study the desorption of individual chitosan polymer chains from substrates with varying chemical composition. AFM images of chitosan adsorbed onto a flat mica substrate show elongated single strands or aggregated bundles. The aggregated state of the polymer is consistent with the high level of flexibility and mobility expected for a highly positively charged polymer strand. Conversely, the visualization of elongated strands indicated the presence of stabilizing interactions with the substrate. Surfaces with varying chemical composition (glass, self-assembled monolayer of mercaptoundecanoic acid/decanethiol and polytetrafluoroethylene (PTFE)) were probed with chitosan modified AFM tips and the corresponding desorption energies, calculated from plateau-like features, were attributed to the desorption of individual polymer strands. Desorption energies of 2.0±0.3×10(-20)J, 1.8±0.3×10(-20)J and 3.5±0.3×10(-20)J were obtained for glass, SAM of mercaptoundecanoic/dodecanethiol and PTFE, respectively. These single molecule level results can be used as a basis for investigating chitosan and chitosan-based materials for biomaterial applications. Copyright © 2010 Elsevier B.V. All rights reserved.

Atomic Force Microscopy Based Cell Shape Index

Science.gov (United States)

Adia-Nimuwa, Usienemfon; Mujdat Tiryaki, Volkan; Hartz, Steven; Xie, Kan; Ayres, Virginia

2013-03-01

Stellation is a measure of cell physiology and pathology for several cell groups including neural, liver and pancreatic cells. In the present work, we compare the results of a conventional two-dimensional shape index study of both atomic force microscopy (AFM) and fluorescent microscopy images with the results obtained using a new three-dimensional AFM-based shape index similar to sphericity index. The stellation of astrocytes is investigated on nanofibrillar scaffolds composed of electrospun polyamide nanofibers that has demonstrated promise for central nervous system (CNS) repair. Recent work by our group has given us the ability to clearly segment the cells from nanofibrillar scaffolds in AFM images. The clear-featured AFM images indicated that the astrocyte processes were longer than previously identified at 24h. It was furthermore shown that cell spreading could vary significantly as a function of environmental parameters, and that AFM images could record these variations. The new three-dimensional AFM-based shape index incorporates the new information: longer stellate processes and cell spreading. The support of NSF PHY-095776 is acknowledged.

A new image correction method for live cell atomic force microscopy

International Nuclear Information System (INIS)

Shen, Y; Sun, J L; Zhang, A; Hu, J; Xu, L X

2007-01-01

During live cell imaging via atomic force microscopy (AFM), the interactions between the AFM probe and the membrane yield distorted cell images. In this work, an image correction method was developed based on the force-distance curve and the modified Hertzian model. The normal loading and lateral forces exerted on the cell membrane by the AFM tip were both accounted for during the scanning. Two assumptions were made in modelling based on the experimental measurements: (1) the lateral force on the endothelial cells was linear to the height; (2) the cell membrane Young's modulus could be derived from the displacement measurement of a normal force curve. Results have shown that the model could be used to recover up to 30% of the actual cell height depending on the loading force. The accuracy of the model was also investigated with respect to the loading force and mechanical property of the cell membrane

Automated setpoint adjustment for biological contact mode atomic force microscopy imaging

International Nuclear Information System (INIS)

Casuso, Ignacio; Scheuring, Simon

2010-01-01

Contact mode atomic force microscopy (AFM) is the most frequently used AFM imaging mode in biology. It is about 5-10 times faster than oscillating mode imaging (in conventional AFM setups), and provides topographs of biological samples with sub-molecular resolution and at a high signal-to-noise ratio. Unfortunately, contact mode imaging is sensitive to the applied force and intrinsic force drift: inappropriate force applied by the AFM tip damages the soft biological samples. We present a methodology that automatically searches for and maintains high resolution imaging forces. We found that the vertical and lateral vibrations of the probe during scanning are valuable signals for the characterization of the actual applied force by the tip. This allows automated adjustment and correction of the setpoint force during an experiment. A system that permanently performs this methodology steered the AFM towards high resolution imaging forces and imaged purple membrane at molecular resolution and live cells at high signal-to-noise ratio for hours without an operator.

Analytical Model of the Nonlinear Dynamics of Cantilever Tip-Sample Surface Interactions for Various Acoustic-Atomic Force Microscopies

Science.gov (United States)

Cantrell, John H., Jr.; Cantrell, Sean A.

2008-01-01

A comprehensive analytical model of the interaction of the cantilever tip of the atomic force microscope (AFM) with the sample surface is developed that accounts for the nonlinearity of the tip-surface interaction force. The interaction is modeled as a nonlinear spring coupled at opposite ends to linear springs representing cantilever and sample surface oscillators. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a standard iteration procedure. Solutions are obtained for the phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) techniques including force modulation microscopy, atomic force acoustic microscopy, ultrasonic force microscopy, heterodyne force microscopy, resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), and the commonly used intermittent contact mode (TappingMode) generally available on AFMs. The solutions are used to obtain a quantitative measure of image contrast resulting from variations in the Young modulus of the sample for the amplitude and phase images generated by the A-AFM techniques. Application of the model to RDF-AFUM and intermittent soft contact phase images of LaRC-cp2 polyimide polymer is discussed. The model predicts variations in the Young modulus of the material of 24 percent from the RDF-AFUM image and 18 percent from the intermittent soft contact image. Both predictions are in good agreement with the literature value of 21 percent obtained from independent, macroscopic measurements of sheet polymer material.

Hole-doping of mechanically exfoliated graphene by confined hydration layers

NARCIS (Netherlands)

Bollmann, Tjeerd Rogier Johannes; Antipina, L.Y.; Temmen, M.; Reichling, M.; Sorokin, P.B.

2015-01-01

By the use of non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM), we measure the local surface potential of mechanically exfoliated graphene on the prototypical insulating hydrophilic substrate of CaF2(111). Hydration layers confined between the graphene and the

The use of atomic force microscopy to evaluate warm mix asphalt.

Science.gov (United States)

2013-01-01

The main objective of this study was to use the Atomic Force Microscopy (AFM) to examine the moisture susceptibility : and healing characteristics of Warm Mix Asphalt (WMA) and compare it with those of conventional Hot Mix Asphalt (HMA). To : this en...

High resolution magnetic force microscopy using focussed ion beam modified tips

NARCIS (Netherlands)

Phillips, G.N.; Siekman, Martin Herman; Abelmann, Leon; Lodder, J.C.

2002-01-01

Summary form only given. Magnetic force microscopy (MFM) is well established for imaging surface magnetic stray fields. With commercial microscopes and magnetic tips, images with 50 nm resolution are quite routine; however, obtaining higher resolutions is experimentally more demanding. Higher

The Occurrence of Tidal Hybrid Kelvin-Edge Waves in the Global Ocean

Science.gov (United States)

Kaur, H.; Buijsman, M. C.; Yankovsky, A. E.; Zhang, T.; Jeon, C. H.

2017-12-01

This study presents the analysis of hybrid Kelvin-edge waves on the continental shelves in a global ocean model. Our objective is to find areas where the transition occurs from Kelvin waves to hybrid Kelvin-edge waves. The change in continental shelf width may convert a Kelvin wave into a hybrid Kelvin-edge wave. In this process the group velocity reaches a minimum and tidal energy is radiated on and/or offshore [Zhang 2016]. We extract M2 SSH (Sea Surface Height) and velocity from the Hybrid Coordinate Ocean Model (HYCOM) and calculate barotropic energy fluxes. We analyze these three areas: the Bay of Biscay, the Amazon Shelf and North West Africa. In these three regions, the continental shelf widens in the propagation direction and the alongshore flux changes its direction towards the coast. A transect is taken at different points in these areas to compute the dispersion relations of the waves on the continental shelf. In model simulations, we change the bathymetry of the Bay of Biscay to study the behavior of the hybrid Kelvin-edge waves. BibliographyZhang, T., and A. E Yankovsky. (2016), On the nature of cross-isobath energy fluxes in topographically modified barotropic semidiurnal Kelvin waves, J. Geophys. Res. Oceans, 121, 3058-3074, doi:10.1002/2015JC011617.

Compensator design for improved counterbalancing in high speed atomic force microscopy

OpenAIRE

Bozchalooi, I. S.; Youcef-Toumi, K.; Burns, D. J.; Fantner, G. E.

2011-01-01

High speed atomic force microscopy can provide the possibility of many new scientific observations and applications ranging from nano-manufacturing to the study of biological processes. However, the limited imaging speed has been an imperative drawback of the atomic force microscopes. One of the main reasons behind this limitation is the excitation of the AFM dynamics at high scan speeds, severely undermining the reliability of the acquired images. In this research, we propose a piezo based, ...

Ultrasound estimation and FE analysis of elastic modulus of Kelvin foam

International Nuclear Information System (INIS)

Kim, Nohyu; Yang, Seung Yong

2016-01-01

The elastic modulus of a 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam with 3 mm unit cell is designed and printed layer upon layer to fabricate a Kelvin foam plate of 14 mm thickness with a 3D CAD/printer using ABS plastic. The Kelvin foam plate is completely filled with paraffin wax for impedance matching, so that the acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF) method and is used to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity. Finite element method (FEM) and micromechanics is applied to the Kelvin foam plate to calculate the theoretical elastic modulus using a non-isotropic tetrakaidecahedron model. The predicted elastic modulus of the Kelvin foam plate from FEM and micromechanics model is similar, which is only 3-4% of the bulk material. The experimental value of the elastic modulus from the ultrasonic method is approximately twice as that of the numerical and theoretical methods because of the flexural deformation of the cell edges neglected in the ultrasonic method

Ultrasound estimation and FE analysis of elastic modulus of Kelvin foam

Energy Technology Data Exchange (ETDEWEB)

Kim, Nohyu; Yang, Seung Yong [School of Mechatronics Engineering, Korea University of Technology and Education, Cheonan (Korea, Republic of)

2016-02-15

The elastic modulus of a 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam with 3 mm unit cell is designed and printed layer upon layer to fabricate a Kelvin foam plate of 14 mm thickness with a 3D CAD/printer using ABS plastic. The Kelvin foam plate is completely filled with paraffin wax for impedance matching, so that the acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF) method and is used to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity. Finite element method (FEM) and micromechanics is applied to the Kelvin foam plate to calculate the theoretical elastic modulus using a non-isotropic tetrakaidecahedron model. The predicted elastic modulus of the Kelvin foam plate from FEM and micromechanics model is similar, which is only 3-4% of the bulk material. The experimental value of the elastic modulus from the ultrasonic method is approximately twice as that of the numerical and theoretical methods because of the flexural deformation of the cell edges neglected in the ultrasonic method.

Structure of ordered polyelectrolyte films from atomic-force microscopy and X-ray reflectivity data

International Nuclear Information System (INIS)

Belyaev, V.V.; Tolstikhina, A.L.; Stepina, N.D.; Kayushina, R.L.

1998-01-01

The possible application of atomic-force microscopy and X-ray reflectometry methods to structural studies of polyelectrolyte films obtained due to alternating adsorption of oppositely charged polyanion [sodium polysterenesulfonate (PSS)] and polycation [poly(allylamine) hydrochloride (PAA)] layers on solid substrates has been considered. The atomic-force microscopy study has revealed the characteristic features of the surface topography of samples consisting of different numbers of polyelectrolyte layers deposited from solutions characterized by different ionic strength values. It is shown that the shape of the reflectivity curves obtained from thin polyelectrolyte films depends on their surface structure

Dynamic tunneling force microscopy for characterizing electronic trap states in non-conductive surfaces

Energy Technology Data Exchange (ETDEWEB)

Wang, R.; Williams, C. C., E-mail: clayton@physics.utah.edu [Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112 (United States)

2015-09-15

Dynamic tunneling force microscopy (DTFM) is a scanning probe technique for real space mapping and characterization of individual electronic trap states in non-conductive films with atomic scale spatial resolution. The method is based upon the quantum mechanical tunneling of a single electron back and forth between a metallic atomic force microscopy tip and individual trap states in completely non-conducting surface. This single electron shuttling is measured by detecting the electrostatic force induced on the probe tip at the shuttling frequency. In this paper, the physical basis for the DTFM method is unfolded through a physical model and a derivation of the dynamic tunneling signal as a function of several experimental parameters is shown. Experimental data are compared with the theoretical simulations, showing quantitative consistency and verifying the physical model used. The experimental system is described and representative imaging results are shown.

Langmuir- Blodgett layers of amphiphilic molecules investigated by Atomic Force Microscopy

NARCIS (Netherlands)

Zdravkova, Aneliya Nikolova

2007-01-01

Langmuir - Blodgett technique and Atomic Force Microscopy were used to study the phase behaviour of organic molecules (fatty alcohols and monoacid saturated triglycerides) at air-water and air-solid interfaces. The structure of binary mixed LB monolayers of fatty alcohols was reported. The

Localization and force analysis at the single virus particle level using atomic force microscopy

International Nuclear Information System (INIS)

Liu, Chih-Hao; Horng, Jim-Tong; Chang, Jeng-Shian; Hsieh, Chung-Fan; Tseng, You-Chen; Lin, Shiming

2012-01-01

Highlights: ► Localization of single virus particle. ► Force measurements. ► Force mapping. -- Abstract: Atomic force microscopy (AFM) is a vital instrument in nanobiotechnology. In this study, we developed a method that enables AFM to simultaneously measure specific unbinding force and map the viral glycoprotein at the single virus particle level. The average diameter of virus particles from AFM images and the specificity between the viral surface antigen and antibody probe were integrated to design a three-stage method that sets the measuring area to a single virus particle before obtaining the force measurements, where the influenza virus was used as the object of measurements. Based on the purposed method and performed analysis, several findings can be derived from the results. The mean unbinding force of a single virus particle can be quantified, and no significant difference exists in this value among virus particles. Furthermore, the repeatability of the proposed method is demonstrated. The force mapping images reveal that the distributions of surface viral antigens recognized by antibody probe were dispersed on the whole surface of individual virus particles under the proposed method and experimental criteria; meanwhile, the binding probabilities are similar among particles. This approach can be easily applied to most AFM systems without specific components or configurations. These results help understand the force-based analysis at the single virus particle level, and therefore, can reinforce the capability of AFM to investigate a specific type of viral surface protein and its distributions.

A new image correction method for live cell atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Shen, Y; Sun, J L; Zhang, A; Hu, J; Xu, L X [College of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200030 (China)

2007-04-21

During live cell imaging via atomic force microscopy (AFM), the interactions between the AFM probe and the membrane yield distorted cell images. In this work, an image correction method was developed based on the force-distance curve and the modified Hertzian model. The normal loading and lateral forces exerted on the cell membrane by the AFM tip were both accounted for during the scanning. Two assumptions were made in modelling based on the experimental measurements: (1) the lateral force on the endothelial cells was linear to the height; (2) the cell membrane Young's modulus could be derived from the displacement measurement of a normal force curve. Results have shown that the model could be used to recover up to 30% of the actual cell height depending on the loading force. The accuracy of the model was also investigated with respect to the loading force and mechanical property of the cell membrane.

Dynamic force microscopy with quartz tuning forks at high oscillation amplitudes

International Nuclear Information System (INIS)

Labardi, M

2007-01-01

Dynamic force microscopy (DFM) with the self-oscillator (SO) method allows reasonably high scanning rates even with high Q-factors of the resonant force sensor, typical of cantilevers in ultra-high vacuum and of quartz tuning forks. However, due to simpler interpretation of force spectroscopy measurements, small oscillation amplitudes (sub-nm level) are generally preferred. In applications like 'apertureless' scanning near-field optical microscopy (SNOM), oscillation amplitudes of the order of 5-10 nm are needed to increase optical sensitivity and to apply standard optical artefact suppression methods. This motivates the study of the behaviour of tuning forks driven at such high amplitudes, as compared to usual air-operated cantilevers. Both constant-excitation-amplitude (CE) and constant-oscillation-amplitude (CA) modes of SO-DFM are analysed, since the CA mode is more convenient for SNOM applications, denoting remarkable differences. In particular, possible instability effects, previously found in CE mode, are not anticipated for CA mode. It is shown how resonance and approach ('isophase') curves in both modes can be conveniently described in terms of the usual 'normalized frequency shift' γ and of a 'normalized gain' η, defined as a measurement of surface dissipation

Distinguishing ferritin from apoferritin using magnetic force microscopy

International Nuclear Information System (INIS)

Nocera, Tanya M; Zeng, Yuzhi; Agarwal, Gunjan

2014-01-01

Estimating the amount of iron-replete ferritin versus iron-deficient apoferritin proteins is important in biomedical and nanotechnology applications. This work introduces a simple and novel approach to quantify ferritin by using magnetic force microscopy (MFM). We demonstrate how high magnetic moment probes enhance the magnitude of MFM signal, thus enabling accurate quantitative estimation of ferritin content in ferritin/apoferritin mixtures in vitro. We envisage MFM could be adapted to accurately determine ferritin content in protein mixtures or in small aliquots of clinical samples. (fast track communication)

Distinguishing ferritin from apoferritin using magnetic force microscopy

Science.gov (United States)

Nocera, Tanya M.; Zeng, Yuzhi; Agarwal, Gunjan

2014-11-01

Estimating the amount of iron-replete ferritin versus iron-deficient apoferritin proteins is important in biomedical and nanotechnology applications. This work introduces a simple and novel approach to quantify ferritin by using magnetic force microscopy (MFM). We demonstrate how high magnetic moment probes enhance the magnitude of MFM signal, thus enabling accurate quantitative estimation of ferritin content in ferritin/apoferritin mixtures in vitro. We envisage MFM could be adapted to accurately determine ferritin content in protein mixtures or in small aliquots of clinical samples.

Atomic force microscopy imaging to measure precipitate volume fraction in nickel-based superalloys

International Nuclear Information System (INIS)

Bourhettar, A.; Troyon, M.; Hazotte, A.

1995-01-01

In nickel-based superalloys, quantitative analysis of scanning electron microscopy images fails in providing accurate microstructural data, whereas more efficient techniques are very time-consuming. As an alternative approach, the authors propose to perform quantitative analysis of atomic force microscopy images of polished/etched surfaces (quantitative microprofilometry). This permits the measurement of microstructural parameters and the depth of etching, which is the main source of measurement bias. Thus, nonbiased estimations can be obtained by extrapolation of the measurements up to zero etching depth. In this article, the authors used this approach to estimate the volume fraction of γ' precipitates in a nickel-based superalloy single crystal. Atomic force microscopy images of samples etched for different times show definition, homogeneity, and contrast high enough to perform image analysis. The result after extrapolation is in very good agreement with volume fraction values available from published reports

Investigating biomolecular recognition at the cell surface using atomic force microscopy.

Science.gov (United States)

Wang, Congzhou; Yadavalli, Vamsi K

2014-05-01

Probing the interaction forces that drive biomolecular recognition on cell surfaces is essential for understanding diverse biological processes. Force spectroscopy has been a widely used dynamic analytical technique, allowing measurement of such interactions at the molecular and cellular level. The capabilities of working under near physiological environments, combined with excellent force and lateral resolution make atomic force microscopy (AFM)-based force spectroscopy a powerful approach to measure biomolecular interaction forces not only on non-biological substrates, but also on soft, dynamic cell surfaces. Over the last few years, AFM-based force spectroscopy has provided biophysical insight into how biomolecules on cell surfaces interact with each other and induce relevant biological processes. In this review, we focus on describing the technique of force spectroscopy using the AFM, specifically in the context of probing cell surfaces. We summarize recent progress in understanding the recognition and interactions between macromolecules that may be found at cell surfaces from a force spectroscopy perspective. We further discuss the challenges and future prospects of the application of this versatile technique. Copyright © 2014 Elsevier Ltd. All rights reserved.

Topographic and electronic contrast of the graphene moir´e on Ir(111) probed by scanning tunneling microscopy and noncontact atomic force microscopy

NARCIS (Netherlands)

Sun, Z.; Hämäläinen, K.; Sainio, K.; Lahtinen, J.; Vanmaekelbergh, D.A.M.; Liljeroth, P.

2011-01-01

Epitaxial graphene grown on transition-metal surfaces typically exhibits a moir´e pattern due to the lattice mismatch between graphene and the underlying metal surface. We use both scanning tunneling microscopy (STM) and atomic force microscopy (AFM) to probe the electronic and topographic contrast

Influence of Oxygen Pressure on the Domain Dynamics and Local Electrical Properties of BiFe0.95Mn0.05O3 Thin Films Studied by Piezoresponse Force Microscopy and Conductive Atomic Force Microscopy

Directory of Open Access Journals (Sweden)

Kunyu Zhao

2017-11-01

Full Text Available In this work, we have studied the microstructures, nanodomains, polarization preservation behaviors, and electrical properties of BiFe0.95Mn0.05O3 (BFMO multiferroic thin films, which have been epitaxially created on the substrates of SrRuO3, SrTiO3, and TiN-buffered (001-oriented Si at different oxygen pressures via piezoresponse force microscopy and conductive atomic force microscopy. We found that the pure phase state, inhomogeneous piezoresponse force microscopy (PFM response, low leakage current with unidirectional diode-like properties, and orientation-dependent polarization reversal properties were found in BFMO thin films deposited at low oxygen pressure. Meanwhile, these films under high oxygen pressures resulted in impurities in the secondary phase in BFMO films, which caused a greater leakage that hindered the polarization preservation capability. Thus, this shows the important impact of the oxygen pressure on modulating the physical effects of BFMO films.

High-speed atomic force microscopy combined with inverted optical microscopy for studying cellular events.

Science.gov (United States)

Suzuki, Yuki; Sakai, Nobuaki; Yoshida, Aiko; Uekusa, Yoshitsugu; Yagi, Akira; Imaoka, Yuka; Ito, Shuichi; Karaki, Koichi; Takeyasu, Kunio

2013-01-01

A hybrid atomic force microscopy (AFM)-optical fluorescence microscopy is a powerful tool for investigating cellular morphologies and events. However, the slow data acquisition rates of the conventional AFM unit of the hybrid system limit the visualization of structural changes during cellular events. Therefore, high-speed AFM units equipped with an optical/fluorescence detection device have been a long-standing wish. Here we describe the implementation of high-speed AFM coupled with an optical fluorescence microscope. This was accomplished by developing a tip-scanning system, instead of a sample-scanning system, which operates on an inverted optical microscope. This novel device enabled the acquisition of high-speed AFM images of morphological changes in individual cells. Using this instrument, we conducted structural studies of living HeLa and 3T3 fibroblast cell surfaces. The improved time resolution allowed us to image dynamic cellular events.

Magnetic force microscopy and simulation studies on Co 50 Fe 50 ...

Indian Academy of Sciences (India)

We studied the magnetization reversal mechanism of single-layered Co50Fe50 nanomagnets by measuring the magnetization reversal and using the micromagnetic simulations. The magnetization reversal strongly depends on the thickness of the nanomagnets. In the remanent state, the magnetic force microscopy studies ...

Magnetic resonance force microscopy quantum computer with tellurium donors in silicon.

Science.gov (United States)

Berman, G P; Doolen, G D; Hammel, P C; Tsifrinovich, V I

2001-03-26

We propose a magnetic resonance force microscopy (MRFM)-based nuclear spin quantum computer using tellurium impurities in silicon. This approach to quantum computing combines well-developed silicon technology and expected advances in MRFM. Our proposal does not use electrostatic gates to realize quantum logic operations.

Magnetic Resonance Force Microscopy Quantum Computer with Tellurium Donors in Silicon

International Nuclear Information System (INIS)

Berman, G. P.; Doolen, G. D.; Hammel, P. C.; Tsifrinovich, V. I.

2001-01-01

We propose a magnetic resonance force microscopy (MRFM)-based nuclear spin quantum computer using tellurium impurities in silicon. This approach to quantum computing combines well-developed silicon technology and expected advances in MRFM. Our proposal does not use electrostatic gates to realize quantum logic operations

Atomic Force Microscopy - A Tool to Unveil the Mystery of Biological ...

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Atomic Force Microscopy - A Tool to Unveil the Mystery of Biological Systems ... Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 ...

Humidity effects on scanning polarization force microscopy imaging

Energy Technology Data Exchange (ETDEWEB)

Shen, Yue, E-mail: shenyue@isl.ac.cn [Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai 810008 (China); Key Laboratory of Interfacial Physics and Technology of Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhou, Yuan, E-mail: zhouy@isl.ac.cn [Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai 810008 (China); Sun, Yanxia; Zhang, Lijuan [Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai 810008 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Ying; Hu, Jun; Zhang, Yi [Key Laboratory of Interfacial Physics and Technology of Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

2017-08-01

Highlights: • The humidity dramatically affects the contrast of scanning polarization force microscopy (SPFM) imaging on mica surface. • This influence roots in the sensitive dielectric constant of mica surface to the humidity change. • A strategy of controllable and repeatable imaging the local dielectric properties of nanomaterials with SPFM is proposed. - Abstract: Scanning polarization force microscopy (SPFM) is a useful surface characterization technique to visually characterize and distinguish nanomaterial with different local dielectric properties at nanometer scale. In this paper, taking the individual one-atom-thick graphene oxide (GO) and reduced graphene oxide (rGO) sheets on mica as examples, we described the influences of environmental humidity on SPFM imaging. We found that the apparent heights (AHs) or contrast of SPFM imaging was influenced significantly by relative humidity (RH) at a response time of a few seconds. And this influence rooted in the sensitive dielectric constant of mica surface to the RH change. While dielectric properties of GO and rGO sheets were almost immune to the humidity change. In addition, we gave the method to determine the critical humidity at which the contrast conversion happened under different conditions. And this is important to the contrast control and repeatable imaging of SPFM through RH adjusting. These findings suggest a strategy of controllable and repeatable imaging the local dielectric properties of nanomaterials with SPFM, which is critically important for further distinguishment, manipulation, electronic applications, etc.

Scanning Surface Potential Microscopy of Spore Adhesion on Surfaces

Energy Technology Data Exchange (ETDEWEB)

Lee, Ida [University of Tennessee, Knoxville (UTK); Chung, Eunhyea [Georgia Institute of Technology; Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Tsouris, Costas [ORNL

2012-01-01

The adhesion of spores of Bacillus anthracis - the cause of anthrax and a likely biological threat - to solid surfaces is an important consideration in cleanup after an accidental or deliberate release. However, because of safety concerns, directly studying B. anthracis spores with advanced instrumentation is problematic. As a first step, we are examining the electrostatic potential of Bacillus thuringiensis (Bt), which is a closely related species that is often used as a simulant to study B. anthracis. Scanning surface potential microscopy (SSPM), also known as Kelvin probe force microscopy (KPFM), was used to investigate the influence of relative humidity (RH) on the surface electrostatic potential of Bt that had adhered to silica, mica, or gold substrates. AFM/SSPM side-by-side images were obtained separately in air, at various values of RH, after an aqueous droplet with spores was applied on each surface and allowed to dry before measurements. In the SSPM images, a negative potential on the surface of the spores was observed compared with that of the substrates. The surface potential decreased as the humidity increased. Spores were unable to adhere to a surface with an extremely negative potential, such as mica.

3D Viscoelastic Traction Force Microscopy

Science.gov (United States)

Toyjanova, Jennet; Hannen, Erin; Bar-Kochba, Eyal; Darling, Eric M.; Henann, David L.; Franck, Christian

2014-01-01

Native cell-material interactions occur on materials differing in their structural composition, chemistry, and physical compliance. While the last two decades have shown the importance of traction forces during cell-material interactions, they have been almost exclusively presented on purely elastic in-vitro materials. Yet, most bodily tissue materials exhibit some level of viscoelasticity, which could play an important role in how cells sense and transduce tractions. To expand the realm of cell traction measurements and to encompass all materials from elastic to viscoelastic, this paper presents a general, and comprehensive approach for quantifying 3D cell tractions in viscoelastic materials. This methodology includes the experimental characterization of the time-dependent material properties for any viscoelastic material with the subsequent mathematical implementation of the determined material model into a 3D traction force microscopy (3D TFM) framework. Utilizing this new 3D viscoelastic TFM (3D VTFM) approach, we quantify the influence of viscosity on the overall material traction calculations and quantify the error associated with omitting time-dependent material effects, as is the case for all other TFM formulations. We anticipate that the 3D VTFM technique will open up new avenues of cell-material investigations on even more physiologically relevant time-dependent materials including collagen and fibrin gels. PMID:25170569

A Magnetic Resonance Force Microscopy Quantum Computer with Tellurium Donors in Silicon

OpenAIRE

Berman, G. P.; Doolen, G. D.; Tsifrinovich, V. I.

2000-01-01

We propose a magnetic resonance force microscopy (MRFM)-based nuclear spin quantum computer using tellurium impurities in silicon. This approach to quantum computing combines the well-developed silicon technology with expected advances in MRFM.

Higher order structure of short immunostimulatory oligonucleotides studied by atomic force microscopy

International Nuclear Information System (INIS)

Klein, Dionne C.G.; Latz, Eicke; Espevik, Terje; Stokke, Bjorn T.

2010-01-01

Immunostimulatory CpG-DNA activates the innate immune system by binding to Toll-like receptor 9. Structurally different CpG-containing oligonucleotides trigger a different type of immune response while activating the same receptor. We therefore investigated the higher order structure of two different classes of immunostimulatory CpG-DNA. Class A, which contains a partly self-complementary sequence and poly-G ends, forms duplexes and nanoparticles in salt solution, while class B, which does not contain these features and is purely linear, does not form a duplex or nanoparticles. Results obtained here by high-resolution atomic force microscopy of classes A and B CpG-DNA, reflect these differences in secondary structure. Detailed structural analysis of the atomic force microscopy topographs is presented for two different sample preparation methods.

Higher order structure of short immunostimulatory oligonucleotides studied by atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Klein, Dionne C.G., E-mail: dionne.c.g.klein@ntnu.no [Department of Physics, Norwegian University of Science and Technology, N-7491, Trondheim (Norway); Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7489, Trondheim (Norway); Latz, Eicke [Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7489, Trondheim (Norway); Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605 (United States); Institute of Innate Immunity, University Hospitals, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn (Germany); Espevik, Terje [Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, N-7489, Trondheim (Norway); Stokke, Bjorn T. [Department of Physics, Norwegian University of Science and Technology, N-7491, Trondheim (Norway)

2010-05-15

Immunostimulatory CpG-DNA activates the innate immune system by binding to Toll-like receptor 9. Structurally different CpG-containing oligonucleotides trigger a different type of immune response while activating the same receptor. We therefore investigated the higher order structure of two different classes of immunostimulatory CpG-DNA. Class A, which contains a partly self-complementary sequence and poly-G ends, forms duplexes and nanoparticles in salt solution, while class B, which does not contain these features and is purely linear, does not form a duplex or nanoparticles. Results obtained here by high-resolution atomic force microscopy of classes A and B CpG-DNA, reflect these differences in secondary structure. Detailed structural analysis of the atomic force microscopy topographs is presented for two different sample preparation methods.

Probing the interactions between lignin and inorganic oxides using atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Wang, Jingyu; Qian, Yong, E-mail: qianyong86@163.com; Deng, Yonghong; Liu, Di; Li, Hao; Qiu, Xueqing, E-mail: xueqingqiu66@163.com

2016-12-30

Graphical abstract: The interactions between lignin and inorganic oxides are quantitatively probed by atomic force microscopy, which is fundamental but beneficial for understanding and optimizing the absorption-dispersion and catalytic degradation processes of lignin. - Highlights: • The interactions between lignin and inorganic oxides are measured using AFM. • The adhesion forces between lignin and metal oxides are larger than that in nonmetal systems. • Hydrogen bond plays an important role in lignin-inorganic oxides system. - Abstract: Understanding the interactions between lignin and inorganic oxides has both fundamental and practical importance in industrial and energy fields. In this work, the specific interactions between alkali lignin (AL) and three inorganic oxide substrates in aqueous environment are quantitatively measured using atomic force microscopy (AFM). The results show that the average adhesion force between AL and metal oxide such as Al{sub 2}O{sub 3} or MgO is nearly two times bigger than that between AL and nonmetal oxide such as SiO{sub 2} due to the electrostatic difference and cation-π interaction. When 83% hydroxyl groups of AL is blocked by acetylation, the adhesion forces between AL and Al{sub 2}O{sub 3}, MgO and SiO{sub 2} decrease 43, 35 and 75% respectively, which indicate hydrogen bonds play an important role between AL and inorganic oxides, especially in AL-silica system.

Force microscopy on insulators: imaging of organic molecules

International Nuclear Information System (INIS)

Pfeiffer, O; Gnecco, E; Zimmerli, L; Maier, S; Meyer, E; Nony, L; Bennewitz, R; Diederich, F; Fang, H; Bonifazi, D

2005-01-01

So far, most of the high resolution scanning probe microscopy studies of organic molecules were restricted to metallic substrates. Insulating substrates are mandatory when the molecules need to be electrically decoupled in a electronic circuit. In such a case, atomic force microscopy is required. In this paper we will discuss our recent studies on different organic molecules deposited on KBr surfaces in ultra-high vacuum, and then imaged by AFM at room temperature. The distance between tip and surface was controlled either by the frequency-shift of the cantilever resonance or by the excitation signal required to keep the oscillation amplitude constant. Advantages and drawbacks of both techniques are discussed. The high mobility of the molecules, due to their weak interaction with the substrate, hinders the formation of regular self assembled structures. To overcome this problem we created artificial structures on the surface by annealing and by electron irradiation, which made possible the growth of the molecules onto step edges and their confinement into rectangular pits

Radical Chemistry and Charge Manipulation with an Atomic Force Microscope

Science.gov (United States)

Gross, Leo

The fuctionalization of tips by atomic manipulation dramatically increased the resolution of atomic force microscopy (AFM). The combination of high-resolution AFM with atomic manipulation now offers the unprecedented possibility to custom-design individual molecules by making and breaking bonds with the tip of the microscope and directly characterizing the products on the atomic scale. We recently applied this technique to generate and study reaction intermediates and to investigate chemical reactions trigged by atomic manipulation. We formed diradicals by dissociating halogen atoms and then reversibly triggered ring-opening and -closing reactions via atomic manipulation, allowing us to switch and control the molecule's reactivity, magnetic and optical properties. Additional information about charge states and charge distributions can be obtained by Kelvin probe force spectroscopy. On multilayer insulating films we investigated single-electron attachment, detachment and transfer between individual molecules. EU ERC AMSEL (682144), EU project PAMS (610446).

High-speed atomic force microscopy coming of age

International Nuclear Information System (INIS)

Ando, Toshio

2012-01-01

High-speed atomic force microscopy (HS-AFM) is now materialized. It allows direct visualization of dynamic structural changes and dynamic processes of functioning biological molecules in physiological solutions, at high spatiotemporal resolution. Dynamic molecular events unselectively appear in detail in an AFM movie, facilitating our understanding of how biological molecules operate to function. This review describes a historical overview of technical development towards HS-AFM, summarizes elementary devices and techniques used in the current HS-AFM, and then highlights recent imaging studies. Finally, future challenges of HS-AFM studies are briefly discussed. (topical review)

High-speed atomic force microscopy coming of age

Science.gov (United States)

Ando, Toshio

2012-02-01

High-speed atomic force microscopy (HS-AFM) is now materialized. It allows direct visualization of dynamic structural changes and dynamic processes of functioning biological molecules in physiological solutions, at high spatiotemporal resolution. Dynamic molecular events unselectively appear in detail in an AFM movie, facilitating our understanding of how biological molecules operate to function. This review describes a historical overview of technical development towards HS-AFM, summarizes elementary devices and techniques used in the current HS-AFM, and then highlights recent imaging studies. Finally, future challenges of HS-AFM studies are briefly discussed.

Physical mechanisms of megahertz vibrations and nonlinear detection in ultrasonic force and related microscopies

Energy Technology Data Exchange (ETDEWEB)

Bosse, J. L.; Huey, B. D. [Department of Materials Science and Engineering, 97 North Eagleville Road, Unit 3136, Storrs, Connecticut 06269-3136 (United States); Tovee, P. D.; Kolosov, O. V., E-mail: o.kolosov@lancaster.ac.uk [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

2014-04-14

Use of high frequency (HF) vibrations at MHz frequencies in Atomic Force Microscopy (AFM) advanced nanoscale property mapping to video rates, allowed use of cantilever dynamics for mapping nanomechanical properties of stiff materials, sensing μs time scale phenomena in nanostructures, and enabled detection of subsurface features with nanoscale resolution. All of these methods critically depend on the generally poor characterized HF behaviour of AFM cantilevers in contact with a studied sample, spatial and frequency response of piezotransducers, and transfer of ultrasonic vibrations between the probe and a specimen. Focusing particularly on Ultrasonic Force Microscopy (UFM), this work is also applicable to waveguide UFM, heterodyne force microscopy, and near-field holographic microscopy, all methods that exploit nonlinear tip-surface force interactions at high frequencies. Leveraging automated multidimensional measurements, spectroscopic UFM (sUFM) is introduced to investigate a range of common experimental parameters, including piezotransducer excitation frequency, probed position, ultrasonic amplitude, cantilever geometry, spring constant, and normal force. Consistent with studies of influence of each of these factors, the data-rich sUFM signatures allow efficient optimization of ultrasonic-AFM based measurements, leading to best practices recommendations of using longer cantilevers with lower fundamental resonance, while at the same time increasing the central frequency of HF piezo-actuators, and only comparing results within areas on the order of few μm{sup 2} unless calibrated directly or compared with in-the-imaged area standards. Diverse materials such as Si, Cr, and photoresist are specifically investigated. This work thereby provides essential insight into the reliable use of MHz vibrations with AFM and provides direct evidence substantiating phenomena such as sensitivity to adhesion, diminished friction for certain ultrasonic conditions, and the

Physical mechanisms of megahertz vibrations and nonlinear detection in ultrasonic force and related microscopies

International Nuclear Information System (INIS)

Bosse, J. L.; Huey, B. D.; Tovee, P. D.; Kolosov, O. V.

2014-01-01

Use of high frequency (HF) vibrations at MHz frequencies in Atomic Force Microscopy (AFM) advanced nanoscale property mapping to video rates, allowed use of cantilever dynamics for mapping nanomechanical properties of stiff materials, sensing μs time scale phenomena in nanostructures, and enabled detection of subsurface features with nanoscale resolution. All of these methods critically depend on the generally poor characterized HF behaviour of AFM cantilevers in contact with a studied sample, spatial and frequency response of piezotransducers, and transfer of ultrasonic vibrations between the probe and a specimen. Focusing particularly on Ultrasonic Force Microscopy (UFM), this work is also applicable to waveguide UFM, heterodyne force microscopy, and near-field holographic microscopy, all methods that exploit nonlinear tip-surface force interactions at high frequencies. Leveraging automated multidimensional measurements, spectroscopic UFM (sUFM) is introduced to investigate a range of common experimental parameters, including piezotransducer excitation frequency, probed position, ultrasonic amplitude, cantilever geometry, spring constant, and normal force. Consistent with studies of influence of each of these factors, the data-rich sUFM signatures allow efficient optimization of ultrasonic-AFM based measurements, leading to best practices recommendations of using longer cantilevers with lower fundamental resonance, while at the same time increasing the central frequency of HF piezo-actuators, and only comparing results within areas on the order of few μm 2 unless calibrated directly or compared with in-the-imaged area standards. Diverse materials such as Si, Cr, and photoresist are specifically investigated. This work thereby provides essential insight into the reliable use of MHz vibrations with AFM and provides direct evidence substantiating phenomena such as sensitivity to adhesion, diminished friction for certain ultrasonic conditions, and the particular

Atomic force microscopy and force spectroscopy on the assessment of protein folding and functionality.

Science.gov (United States)

Carvalho, Filomena A; Martins, Ivo C; Santos, Nuno C

2013-03-01

Atomic force microscopy (AFM) applied to biological systems can, besides generating high-quality and well-resolved images, be employed to study protein folding via AFM-based force spectroscopy. This approach allowed remarkable advances in the measurement of inter- and intramolecular interaction forces with piconewton resolution. The detection of specific interaction forces between molecules based on the AFM sensitivity and the manipulation of individual molecules greatly advanced the understanding of intra-protein and protein-ligand interactions. Apart from the academic interest in the resolution of basic scientific questions, this technique has also key importance on the clarification of several biological questions of immediate biomedical relevance. Force spectroscopy is an especially appropriate technique for "mechanical proteins" that can provide crucial information on single protein molecules and/or domains. Importantly, it also has the potential of combining in a single experiment spatial and kinetic measurements. Here, the main principles of this methodology are described, after which the ability to measure interactions at the single-molecule level is discussed, in the context of relevant protein-folding examples. We intend to demonstrate the potential of AFM-based force spectroscopy in the study of protein folding, especially since this technique is able to circumvent some of the difficulties typically encountered in classical thermal/chemical denaturation studies. Copyright © 2012 Elsevier Inc. All rights reserved.

Nuclear order in silver at pico-Kelvin temperature

DEFF Research Database (Denmark)

Siemensmeyer, K.; Clausen, K.N.; Lefmann, K.

1997-01-01

Nuclear order in silver is observed by neutron diffraction at pico-Kelvin temperatures. The structure is a type-I antiferromagnet with critical field of 100 mu T. The entropy-field phase diagram was determined using the spin-dependent absorption.......Nuclear order in silver is observed by neutron diffraction at pico-Kelvin temperatures. The structure is a type-I antiferromagnet with critical field of 100 mu T. The entropy-field phase diagram was determined using the spin-dependent absorption....

High resolution magnetic force microscopy: instrumentation and application for recording media

NARCIS (Netherlands)

Porthun, Steffen; Porthun, S.

This thesis describes aspects of the use of magnetic force microscopy for the study of magnetic recording media. The maximum achievable storage density in magnetic recording is limited by the magnetic reversal behaviour of the medium and by the stability of the written information. The shape and

Tip radius preservation for high resolution imaging in amplitude modulation atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Ramos, Jorge R., E-mail: jorge.rr@cea.cu [Instituto de Ciencia de Materiales de Madrid, Sor Juana Inés de la Cruz 3, Canto Blanco, 28049 Madrid, España (Spain)

2014-07-28

The acquisition of high resolution images in atomic force microscopy (AFM) is correlated to the cantilever's tip shape, size, and imaging conditions. In this work, relative tip wear is quantified based on the evolution of a direct experimental observable in amplitude modulation atomic force microscopy, i.e., the critical amplitude. We further show that the scanning parameters required to guarantee a maximum compressive stress that is lower than the yield/fracture stress of the tip can be estimated via experimental observables. In both counts, the optimized parameters to acquire AFM images while preserving the tip are discussed. The results are validated experimentally by employing IgG antibodies as a model system.

Modeling noncontact atomic force microscopy resolution on corrugated surfaces

Directory of Open Access Journals (Sweden)

Kristen M. Burson

2012-03-01

Full Text Available Key developments in NC-AFM have generally involved atomically flat crystalline surfaces. However, many surfaces of technological interest are not atomically flat. We discuss the experimental difficulties in obtaining high-resolution images of rough surfaces, with amorphous SiO2 as a specific case. We develop a quasi-1-D minimal model for noncontact atomic force microscopy, based on van der Waals interactions between a spherical tip and the surface, explicitly accounting for the corrugated substrate (modeled as a sinusoid. The model results show an attenuation of the topographic contours by ~30% for tip distances within 5 Å of the surface. Results also indicate a deviation from the Hamaker force law for a sphere interacting with a flat surface.

Localization and force analysis at the single virus particle level using atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Liu, Chih-Hao [Institute of Applied Mechanics, Nation Taiwan University, Roosevelt Road, Taipei 10617, Taiwan (China); Horng, Jim-Tong [Department of Biochemistry, Chang Gung University, 259 Wen-Hwa First Road, Kweishan, Taoyuan 333, Taiwan (China); Chang, Jeng-Shian [Institute of Applied Mechanics, Nation Taiwan University, Roosevelt Road, Taipei 10617, Taiwan (China); Hsieh, Chung-Fan [Graduate Institute of Biomedical Sciences, Chang Gung University, Kweishan, Taoyuan 333, Taiwan (China); Tseng, You-Chen [Institute of Applied Mechanics, Nation Taiwan University, Roosevelt Road, Taipei 10617, Taiwan (China); Lin, Shiming, E-mail: til@ntu.edu.tw [Institute of Applied Mechanics, Nation Taiwan University, Roosevelt Road, Taipei 10617, Taiwan (China); Center for Optoelectronic Biomedicine, College of Medicine, Nation Taiwan University, 1-1 Jen-Ai Road, Taipei 10051, Taiwan (China)

2012-01-06

Highlights: Black-Right-Pointing-Pointer Localization of single virus particle. Black-Right-Pointing-Pointer Force measurements. Black-Right-Pointing-Pointer Force mapping. -- Abstract: Atomic force microscopy (AFM) is a vital instrument in nanobiotechnology. In this study, we developed a method that enables AFM to simultaneously measure specific unbinding force and map the viral glycoprotein at the single virus particle level. The average diameter of virus particles from AFM images and the specificity between the viral surface antigen and antibody probe were integrated to design a three-stage method that sets the measuring area to a single virus particle before obtaining the force measurements, where the influenza virus was used as the object of measurements. Based on the purposed method and performed analysis, several findings can be derived from the results. The mean unbinding force of a single virus particle can be quantified, and no significant difference exists in this value among virus particles. Furthermore, the repeatability of the proposed method is demonstrated. The force mapping images reveal that the distributions of surface viral antigens recognized by antibody probe were dispersed on the whole surface of individual virus particles under the proposed method and experimental criteria; meanwhile, the binding probabilities are similar among particles. This approach can be easily applied to most AFM systems without specific components or configurations. These results help understand the force-based analysis at the single virus particle level, and therefore, can reinforce the capability of AFM to investigate a specific type of viral surface protein and its distributions.

Probing the compressibility of tumor cell nuclei by combined atomic force-confocal microscopy

Science.gov (United States)

Krause, Marina; te Riet, Joost; Wolf, Katarina

2013-12-01

The cell nucleus is the largest and stiffest organelle rendering it the limiting compartment during migration of invasive tumor cells through dense connective tissue. We here describe a combined atomic force microscopy (AFM)-confocal microscopy approach for measurement of bulk nuclear stiffness together with simultaneous visualization of the cantilever-nucleus contact and the fate of the cell. Using cantilevers functionalized with either tips or beads and spring constants ranging from 0.06-10 N m-1, force-deformation curves were generated from nuclear positions of adherent HT1080 fibrosarcoma cell populations at unchallenged integrity, and a nuclear stiffness range of 0.2 to 2.5 kPa was identified depending on cantilever type and the use of extended fitting models. Chromatin-decondensating agent trichostatin A (TSA) induced nuclear softening of up to 50%, demonstrating the feasibility of our approach. Finally, using a stiff bead-functionalized cantilever pushing at maximal system-intrinsic force, the nucleus was deformed to 20% of its original height which after TSA treatment reduced further to 5% remaining height confirming chromatin organization as an important determinant of nuclear stiffness. Thus, combined AFM-confocal microscopy is a feasible approach to study nuclear compressibility to complement concepts of limiting nuclear deformation in cancer cell invasion and other biological processes.

Role of tip chemical reactivity on atom manipulation process in dynamic force microscopy

Czech Academy of Sciences Publication Activity Database

Sugimoto, Y.; Yurtsever, A.; Abe, M.; Morita, S.; Ondráček, Martin; Pou, P.; Perez, R.; Jelínek, Pavel

2013-01-01

Roč. 7, č. 8 (2013), s. 7370-7376 ISSN 1936-0851 R&D Projects: GA ČR(CZ) GPP204/11/P578 Grant - others:GA AV ČR(CZ) M100101207 Institutional support: RVO:68378271 Keywords : noncontact atomic force microscopy * atomic manipulation * force spectroscopy * chemical interaction force * DFT simulations * nudged elastic band Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 12.033, year: 2013 http://pubs.acs.org/doi/abs/10.1021/nn403097p

Detection of magnetic-labeled antibody specific recognition events by combined atomic force and magnetic force microscopy

International Nuclear Information System (INIS)

Hong Xia; Liu Yanmei; Li Jun; Guo Wei; Bai Yubai

2009-01-01

Atomic force (AFM) and magnetic force microscopy (MFM) were developed to detect biomolecular specific interaction. Goat anti-mouse immunoglobulin (anti-IgG) was covalently attached onto gold substrate modified by a self-assembly monolayer of thioctic acid via 1-ethyl-3-[3-(dimethylamino) propyl] carbodiimide (EDC) activation. Magnetic-labeled IgG then specifically adsorbed onto anti-IgG surface. The morphological variation was identified by AFM. MFM was proved to be a fine assistant tool to distinguish the immunorecognized nanocomposites from the impurities by detection of the magnetic signal from magnetic-labeled IgG. It would enhance the understanding of biomolecular recognition process.

Detection of magnetic-labeled antibody specific recognition events by combined atomic force and magnetic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Hong Xia [Center for Advanced Optoelectronic Functional Materials Research, Key Laboratory of UV Light-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun 130024 (China); College of Chemistry, Jilin University, Changchun 130023 (China)], E-mail: xiahong@nenu.edu.cn; Liu Yanmei; Li Jun; Guo Wei; Bai Yubai [College of Chemistry, Jilin University, Changchun 130023 (China)

2009-09-15

Atomic force (AFM) and magnetic force microscopy (MFM) were developed to detect biomolecular specific interaction. Goat anti-mouse immunoglobulin (anti-IgG) was covalently attached onto gold substrate modified by a self-assembly monolayer of thioctic acid via 1-ethyl-3-[3-(dimethylamino) propyl] carbodiimide (EDC) activation. Magnetic-labeled IgG then specifically adsorbed onto anti-IgG surface. The morphological variation was identified by AFM. MFM was proved to be a fine assistant tool to distinguish the immunorecognized nanocomposites from the impurities by detection of the magnetic signal from magnetic-labeled IgG. It would enhance the understanding of biomolecular recognition process.

Stern potential and Debye length measurements in dilute ionic solutions with electrostatic force microscopy.

Science.gov (United States)

Kumar, Bharat; Crittenden, Scott R

2013-11-01

We demonstrate the ability to measure Stern potential and Debye length in dilute ionic solution with atomic force microscopy. We develop an analytic expression for the second harmonic force component of the capacitive force in an ionic solution from the linearized Poisson-Boltzmann equation. This allows us to calibrate the AFM tip potential and, further, obtain the Stern potential of sample surfaces. In addition, the measured capacitive force is independent of van der Waals and double layer forces, thus providing a more accurate measure of Debye length.

Ultrasonically synthesized organic liquid-filled chitosan microcapsules: part 2: characterization using AFM (atomic force microscopy) and combined AFM-confocal laser scanning fluorescence microscopy.

Science.gov (United States)

Mettu, Srinivas; Ye, Qianyu; Zhou, Meifang; Dagastine, Raymond; Ashokkumar, Muthupandian

2018-04-25

Atomic Force Microscopy (AFM) is used to measure the stiffness and Young's modulus of individual microcapsules that have a chitosan cross-linked shell encapsulating tetradecane. The oil filled microcapsules were prepared using a one pot synthesis via ultrasonic emulsification of tetradecane and crosslinking of the chitosan shell in aqueous solutions of acetic acid. The concentration of acetic acid in aqueous solutions of chitosan was varied from 0.2% to 25% v/v. The effect of acetic acid concentration and size of the individual microcapsules on the strength was probed. The deformations and forces required to rupture the microcapsules were also measured. Three dimensional deformations of microcapsules under large applied loads were obtained by the combination of Laser Scanning Confocal Microscopy (LSCM) with Atomic Force Microscopy (AFM). The stiffness, and hence the modulus, of the microcapsules was found to decrease with an increase in size with the average stiffness ranging from 82 to 111 mN m-1 and average Young's modulus ranging from 0.4 to 6.5 MPa. The forces required to rupture the microcapsules varied from 150 to 250 nN with deformations of the microcapsules up to 62 to 110% relative to their radius, respectively. Three dimensional images obtained using laser scanning confocal microscopy showed that the microcapsules retained their structure and shape after being subjected to large deformations and subsequent removal of the loads. Based on the above observations, the oil filled chitosan crosslinked microcapsules are an ideal choice for use in the food and pharmaceutical industries as they would be able to withstand the process conditions encountered.

Polarizability of DNA Block Copolymer Nanoparticles Observed by Electrostatic Force Microscopy

NARCIS (Netherlands)

Sowwan, Mukhles; Faroun, Maryam; Mentovich, Elad; Ibrahim, Imad; Haboush, Shayma; Alemdaroglu, Fikri Emrah; Kwak, Minseok; Richter, Shachar; Herrmann, Andreas

2010-01-01

In this study, DNA block copolymer (DBC) micelles with a polystyrene (PS) core and a single-stranded (ss) DNA shell were doped with ferrocene (Fc) molecules. Tapping mode atomic force microscopy (AFM) was used to study the morphology of the doped and undoped block copolymer aggregates. We show that

Characterization of gold nanoparticle films: Rutherford backscattering spectroscopy, scanning electron microscopy with image analysis, and atomic force microscopy

Directory of Open Access Journals (Sweden)

Pia C. Lansåker

2014-10-01

Full Text Available Gold nanoparticle films are of interest in several branches of science and technology, and accurate sample characterization is needed but technically demanding. We prepared such films by DC magnetron sputtering and recorded their mass thickness by Rutherford backscattering spectroscopy. The geometric thickness dg—from the substrate to the tops of the nanoparticles—was obtained by scanning electron microscopy (SEM combined with image analysis as well as by atomic force microscopy (AFM. The various techniques yielded an internally consistent characterization of the films. In particular, very similar results for dg were obtained by SEM with image analysis and by AFM.

Free-standing biomimetic polymer membrane imaged with atomic force microscopy

DEFF Research Database (Denmark)

Rein, Christian; Pszon-Bartosz, Kamila Justyna; Jensen, Karin Bagger Stibius

2011-01-01

Fluid polymeric biomimetic membranes are probed with atomic force microscopy (AFM) using probes with both normal tetrahedrally shaped tips and nanoneedle-shaped Ag2Ga rods. When using nanoneedle probes, the collected force volume data show three distinct membrane regions which match the expected...... membrane structure when spanning an aperture in a hydrophobic scaffold. The method used provides a general method for mapping attractive fluid surfaces. In particular, the nanoneedle probing allows for characterization of free-standing biomimetic membranes with thickness on the nanometer scale suspended...... over 300-μm-wide apertures, where the membranes are stable toward hundreds of nanoindentations without breakage. © 2010 American Chemical Society....

Atomic force microscopy for university students: applications in biomaterials

International Nuclear Information System (INIS)

Kontomaris, S V; Stylianou, A

2017-01-01

Atomic force microscopy (AFM) is a powerful tool used in the investigation of the structural and mechanical properties of a wide range of materials including biomaterials. It provides the ability to acquire high resolution images of biomaterials at the nanoscale. It also provides information about the response of specific areas under controlled applied force, which leads to the mechanical characterization of the sample at the nanoscale. The wide range of information provided by AFM has established it as a powerful research tool. In this paper, we present a general overview of the basic operation and functions of AFM applications in biomaterials. The basic operation of AFM is explained in detail with a focus on the real interactions that take place at the nanoscale level during imaging. AFM’s ability to provide the mechanical characterization (force curves) of specific areas at the nanoscale is also explained. The basic models of applied mechanics that are used for processing the data obtained by the force curves are presented. The aim of this paper is to provide university students and young scientists in the fields of biophysics and nanotechnology with a better understanding of AFM. (review)

A Study of Electrostatic Charge on Insulating Film by Electrostatic Force Microscopy

International Nuclear Information System (INIS)

Kikunaga, K; Toosaka, K; Kamohara, T; Sakai, K; Nonaka, K

2011-01-01

Electrostatic charge properties on polypropylene film have been characterized by atomic force microscopy and electrostatic force microscopy. The measurements have been carried out after the polypropylene film was electrified by contact and separation process in an atmosphere of controlled humidity. The negative and positive charge in concave surface has been observed. The correlation between concave surface and charge position suggests that the electrostatic charges could be caused by localized contact. On the other hand, positive charge on a flat surface has been observed. The absence of a relationship between surface profile and charge position suggests that the electrostatic charge should be caused by discharge during the separation process. The spatial migration of other positive charges through surface roughness has been observed. The results suggest that there could be some electron traps on the surface roughness and some potentials on the polypropylene film.

Competition of elastic and adhesive properties of carbon nanotubes anchored to atomic force microscopy tips

International Nuclear Information System (INIS)

Bernard, Charlotte; Marsaudon, Sophie; Boisgard, Rodolphe; Aime, Jean-Pierre

2008-01-01

In this paper we address the mechanical properties of carbon nanotubes anchored to atomic force microscopy (AFM) tips in a detailed analysis of experimental results and exhaustive description of a simple model. We show that volume elastic and surface adhesive forces both contribute to the dynamical AFM experimental signals. Their respective weights depend on the nanotube properties and on an experimental parameter: the oscillation amplitude. To quantify the elastic and adhesive contributions, a simple analytical model is used. It enables analytical expressions of the resonance frequency shift and dissipation that can be measured in the atomic force microscopy dynamical frequency modulation mode. It includes the nanotube adhesive contribution to the frequency shift. Experimental data for single-wall and multi-wall carbon nanotubes compare well to the model predictions for different oscillation amplitudes. Three parameters can be extracted: the distance necessary to unstick the nanotube from the surface and two spring constants corresponding to tube compression and to the elastic force required to overcome the adhesion force

Stern potential and Debye length measurements in dilute ionic solutions with electrostatic force microscopy

International Nuclear Information System (INIS)

Kumar, Bharat; Crittenden, Scott R

2013-01-01

We demonstrate the ability to measure Stern potential and Debye length in dilute ionic solution with atomic force microscopy. We develop an analytic expression for the second harmonic force component of the capacitive force in an ionic solution from the linearized Poisson–Boltzmann equation. This allows us to calibrate the AFM tip potential and, further, obtain the Stern potential of sample surfaces. In addition, the measured capacitive force is independent of van der Waals and double layer forces, thus providing a more accurate measure of Debye length. (paper)

Kelvin-Helmholtz instability as a possible cause of edge localized modes

International Nuclear Information System (INIS)

Strauss, H.R.

1992-01-01

Edge localized modes may be a Kelvin-Helmholtz instability caused by the sheared rotation of H-mode plasmas. The Kelvin-Helmholtz instability is stabilized by coupling to Alfven waves. There is a critical velocity gradient, of the order of the Alfven velocity divided by the magnetic shear length. This is verified in a numerical simulation. The critical velocity shear is consistent with experiment. A non-linear simulation shows how the Kelvin-Helmholtz mode can cause oscillations of the velocity profile. (author). Letter-to-the-editor. 13 refs, 6 figs

The development of the spatially correlated adjustment wavelet filter for atomic force microscopy data

Energy Technology Data Exchange (ETDEWEB)

Sikora, Andrzej, E-mail: sikora@iel.wroc.pl [Electrotechnical Institute, Division of Electrotechnology and Materials Science, M. Skłodowskiej-Curie 55/61, 50-369 Wrocław (Poland); Rodak, Aleksander [Faculty of Electronics, Wrocław University of Technology, Janiszewskiego 11/17, 50-372 Wrocław (Poland); Unold, Olgierd [Institute of Computer Engineering, Control and Robotics, Faculty of Electronics, Wrocław University of Technology, Janiszewskiego 11/17, 50-372 Wrocław (Poland); Klapetek, Petr [Czech Metrology Institute, Okružní 31, 638 00 Brno (Czech Republic)

2016-12-15

In this paper a novel approach for the practical utilization of the 2D wavelet filter in terms of the artifacts removal from atomic force microscopy measurements results is presented. The utilization of additional data such as summary photodiode signal map is implemented in terms of the identification of the areas requiring the data processing, filtering settings optimization and the verification of the process performance. Such an approach allows to perform the filtering parameters adjustment by average user, while the straightforward method requires an expertise in this field. The procedure was developed as the function of the Gwyddion software. The examples of filtering the phase imaging and Electrostatic Force Microscopy measurement result are presented. As the wavelet filtering feature may remove a local artifacts, its superior efficiency over similar approach with 2D Fast Fourier Transformate based filter (2D FFT) can be noticed. - Highlights: • A novel approach to 2D wavelet-based filter for atomic force microscopy is shown. • The additional AFM measurement signal is used to adjust the filter. • Efficient removal of the local interference phenomena caused artifacts is presented.

The development of the spatially correlated adjustment wavelet filter for atomic force microscopy data

International Nuclear Information System (INIS)

Sikora, Andrzej; Rodak, Aleksander; Unold, Olgierd; Klapetek, Petr

2016-01-01

In this paper a novel approach for the practical utilization of the 2D wavelet filter in terms of the artifacts removal from atomic force microscopy measurements results is presented. The utilization of additional data such as summary photodiode signal map is implemented in terms of the identification of the areas requiring the data processing, filtering settings optimization and the verification of the process performance. Such an approach allows to perform the filtering parameters adjustment by average user, while the straightforward method requires an expertise in this field. The procedure was developed as the function of the Gwyddion software. The examples of filtering the phase imaging and Electrostatic Force Microscopy measurement result are presented. As the wavelet filtering feature may remove a local artifacts, its superior efficiency over similar approach with 2D Fast Fourier Transformate based filter (2D FFT) can be noticed. - Highlights: • A novel approach to 2D wavelet-based filter for atomic force microscopy is shown. • The additional AFM measurement signal is used to adjust the filter. • Efficient removal of the local interference phenomena caused artifacts is presented.

Molecular structure of dipalmitoylphospatidylcholine Langmuir-Blodgett monolayers studied by atomic force microscopy.

NARCIS (Netherlands)

Zhai, X.; Kleijn, J.M.

1997-01-01

Monolayers of dipalmitoylphosphatidylcholine (DPPC) on the air-water interface have been transferred at various surface pressures onto quartz substrates using the Langmuir-Blodgett (LB) technique. The topography of these layers, on a molecular scale, has been examined by atomic force microscopy

Influence of Surface Adsorption on Work Function Measurements on Gold-Platinum Interface Using Scanning Kelvin Probe Microscopy

International Nuclear Information System (INIS)

Mugo, Simon; Yuan Jun

2012-01-01

Surface potential difference (SPD) on freshly coated gold and platinum electrodes have been found to be much smaller than bulk work functions consideration and to be dependent on time. We show these discrepancies arise due to formation of surface dipoles caused by adsorbed contaminants in ambient environments. The process is reversible by gentle annealing consistent with contaminant hypothesis. Examination of potential changes on individual electrodes suggest that the Pt surface is more sensitive to ambient conditions than the Au surface in accordance with their relative chemical activities. The result has great implication for interpretation of Kelvin probe measurements obtained on practical devices exposed to ambient environments.

Atomic force microscopy imaging and single molecule recognition force spectroscopy of coat proteins on the surface of Bacillus subtilis spore.

Science.gov (United States)

Tang, Jilin; Krajcikova, Daniela; Zhu, Rong; Ebner, Andreas; Cutting, Simon; Gruber, Hermann J; Barak, Imrich; Hinterdorfer, Peter

2007-01-01

Coat assembly in Bacillus subtilis serves as a tractable model for the study of the self-assembly process of biological structures and has a significant potential for use in nano-biotechnological applications. In the present study, the morphology of B. subtilis spores was investigated by magnetically driven dynamic force microscopy (MAC mode atomic force microscopy) under physiological conditions. B. subtilis spores appeared as prolate structures, with a length of 0.6-3 microm and a width of about 0.5-2 microm. The spore surface was mainly covered with bump-like structures with diameters ranging from 8 to 70 nm. Besides topographical explorations, single molecule recognition force spectroscopy (SMRFS) was used to characterize the spore coat protein CotA. This protein was specifically recognized by a polyclonal antibody directed against CotA (anti-CotA), the antibody being covalently tethered to the AFM tip via a polyethylene glycol linker. The unbinding force between CotA and anti-CotA was determined as 55 +/- 2 pN. From the high-binding probability of more than 20% in force-distance cycles it is concluded that CotA locates in the outer surface of B. subtilis spores. Copyright (c) 2007 John Wiley & Sons, Ltd.

Impact of thermal frequency drift on highest precision force microscopy using quartz-based force sensors at low temperatures

Directory of Open Access Journals (Sweden)

Florian Pielmeier

2014-04-01

Full Text Available In frequency modulation atomic force microscopy (FM-AFM the stability of the eigenfrequency of the force sensor is of key importance for highest precision force measurements. Here, we study the influence of temperature changes on the resonance frequency of force sensors made of quartz, in a temperature range from 4.8–48 K. The sensors are based on the qPlus and length extensional principle. The frequency variation with temperature T for all sensors is negative up to 30 K and on the order of 1 ppm/K, up to 13 K, where a distinct kink appears, it is linear. Furthermore, we characterize a new type of miniaturized qPlus sensor and confirm the theoretically predicted reduction in detector noise.

Nanostructure and force spectroscopy analysis of human peripheral blood CD4+ T cells using atomic force microscopy

International Nuclear Information System (INIS)

Hu Mingqian; Wang Jiongkun; Cai Jiye; Wu Yangzhe; Wang Xiaoping

2008-01-01

To date, nanoscale imaging of the morphological changes and adhesion force of CD4 + T cells during in vitro activation remains largely unreported. In this study, we used atomic force microscopy (AFM) to study the morphological changes and specific binding forces in resting and activated human peripheral blood CD4 + T cells. The AFM images revealed that the volume of activated CD4 + T cells increased and the ultrastructure of these cells also became complex. Using a functionalized AFM tip, the strength of the specific binding force of the CD4 antigen-antibody interaction was found to be approximately three times that of the unspecific force. The adhesion forces were not randomly distributed over the surface of a single activated CD4 + T cell, indicated that the CD4 molecules concentrated into nanodomains. The magnitude of the adhesion force of the CD4 antigen-antibody interaction did not change markedly with the activation time. Multiple bonds involved in the CD4 antigen-antibody interaction were measured at different activation times. These results suggest that the adhesion force involved in the CD4 antigen-antibody interaction is highly selective and of high affinity

Nanostructure and force spectroscopy analysis of human peripheral blood CD4+ T cells using atomic force microscopy.

Science.gov (United States)

Hu, Mingqian; Wang, Jiongkun; Cai, Jiye; Wu, Yangzhe; Wang, Xiaoping

2008-09-12

To date, nanoscale imaging of the morphological changes and adhesion force of CD4(+) T cells during in vitro activation remains largely unreported. In this study, we used atomic force microscopy (AFM) to study the morphological changes and specific binding forces in resting and activated human peripheral blood CD4(+) T cells. The AFM images revealed that the volume of activated CD4(+) T cells increased and the ultrastructure of these cells also became complex. Using a functionalized AFM tip, the strength of the specific binding force of the CD4 antigen-antibody interaction was found to be approximately three times that of the unspecific force. The adhesion forces were not randomly distributed over the surface of a single activated CD4(+) T cell, indicated that the CD4 molecules concentrated into nanodomains. The magnitude of the adhesion force of the CD4 antigen-antibody interaction did not change markedly with the activation time. Multiple bonds involved in the CD4 antigen-antibody interaction were measured at different activation times. These results suggest that the adhesion force involved in the CD4 antigen-antibody interaction is highly selective and of high affinity.

Backscattering position detection for photonic force microscopy

International Nuclear Information System (INIS)

Volpe, Giovanni; Kozyreff, Gregory; Petrov, Dmitri

2007-01-01

An optically trapped particle is an extremely sensitive probe for the measurement of pico- and femto-Newton forces between the particle and its environment in microscopic systems (photonic force microscopy). A typical setup comprises an optical trap, which holds the probe, and a position sensing system, which uses the scattering of a beam illuminating the probe. Usually the position is accurately determined by measuring the deflection of the forward-scattered light transmitted through the probe. However, geometrical constraints may prevent access to this side of the trap, forcing one to make use of the backscattered light instead. A theory is presented together with numerical results that describes the use of the backscattered light for position detection. With a Mie-Debye approach, we compute the total (incident plus scattered) field and follow its evolution as it is collected by the condenser lenses and projected onto the position detectors and the responses of position sensitive detectors and quadrant photodetectors to the displacement of the probe in the optical trap, both in forward and backward configurations. We find out that in the case of backward detection, for both types of detectors the displacement sensitivity can change sign as a function of the probe size and is null for some critical sizes. In addition, we study the influence of the numerical aperture of the detection system, polarization, and the cross talk between position measurements in orthogonal directions. We finally discuss how these features should be taken into account in experimental designs

Electron beam fabrication and characterization of high- resolution magnetic force microscopy tips

NARCIS (Netherlands)

Ruhrig, M.; Rührig, M.; Porthun, S.; Porthun, S.; Lodder, J.C.; Mc vitie, S.; Heyderman, L.J.; Johnston, A.B.; Chapman, J.N.

1996-01-01

The stray field, magnetic microstructure, and switching behavior of high‐resolution electron beam fabricated thin film tips for magnetic force microscopy (MFM) are investigated with different imaging modes in a transmission electron microscope (TEM). As the tiny smooth carbon needles covered with a

Acoustic Imaging Frequency Dynamics of Ferroelectric Domains by Atomic Force Microscopy

International Nuclear Information System (INIS)

Kun-Yu, Zhao; Hua-Rong, Zeng; Hong-Zhang, Song; Sen-Xing, Hui; Guo-Rong, Li; Qing-Rui, Yin; Shimamura, Kiyoshi; Kannan, Chinna Venkadasamy; Villora, Encarnacion Antonia Garcia; Takekawa, Shunji; Kitamura, Kenji

2008-01-01

We report the acoustic imaging frequency dynamics of ferroelectric domains by low-frequency acoustic probe microscopy based on the commercial atomic force microscopy It is found that ferroelectric domain could be firstly visualized at lower frequency down to 0.5 kHz by AFM-based acoustic microscopy The frequency-dependent acoustic signal revealed a strong acoustic response in the frequency range from 7kHz to 10kHz, and reached maximum at 8.1kHz. The acoustic contrast mechanism can be ascribed to the different elastic response of ferroelectric microstructures to local elastic stress fields, which is induced by the acoustic wave transmitting in the sample when the piezoelectric transducer is vibrating and exciting acoustic wave under ac electric fields due to normal piezoelectric effects. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Noncontact atomic force microscopy in liquid environment with quartz tuning fork and carbon nanotube probe

DEFF Research Database (Denmark)

Kageshima, M.; Jensenius, Henriette; Dienwiebel, M.

2002-01-01

A force sensor for noncontact atomic force microscopy in liquid environment was developed by combining a multiwalled carbon nanotube (MWNT) probe with a quartz tuning fork. Solvation shells of octamethylcyclotetrasiloxane surface were detected both in the frequency shift and dissipation. Due to t...

Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

International Nuclear Information System (INIS)

Morawski, Ireneusz; Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert

2015-01-01

A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations

Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

Energy Technology Data Exchange (ETDEWEB)

Morawski, Ireneusz [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany); Institute of Experimental Physics, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław (Poland); Spiegelberg, Richard; Korte, Stefan; Voigtländer, Bert [Peter Grünberg Institut (PGI-3) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich (Germany)

2015-12-15

A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. The high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations.

Fast time-resolved electrostatic force microscopy: Achieving sub-cycle time resolution

Energy Technology Data Exchange (ETDEWEB)

Karatay, Durmus U.; Harrison, Jeffrey S.; Glaz, Micah S.; Giridharagopal, Rajiv; Ginger, David S., E-mail: ginger@chem.washington.edu [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States)

2016-05-15

The ability to measure microsecond- and nanosecond-scale local dynamics below the diffraction limit with widely available atomic force microscopy hardware would enable new scientific studies in fields ranging from biology to semiconductor physics. However, commercially available scanning-probe instruments typically offer the ability to measure dynamics only on time scales of milliseconds to seconds. Here, we describe in detail the implementation of fast time-resolved electrostatic force microscopy using an oscillating cantilever as a means to measure fast local dynamics following a perturbation to a sample. We show how the phase of the oscillating cantilever relative to the perturbation event is critical to achieving reliable sub-cycle time resolution. We explore how noise affects the achievable time resolution and present empirical guidelines for reducing noise and optimizing experimental parameters. Specifically, we show that reducing the noise on the cantilever by using photothermal excitation instead of piezoacoustic excitation further improves time resolution. We demonstrate the discrimination of signal rise times with time constants as fast as 10 ns, and simultaneous data acquisition and analysis for dramatically improved image acquisition times.

Step-edge calibration of torsional sensitivity for lateral force microscopy

International Nuclear Information System (INIS)

Sul, Onejae; Jang, Seongjin; Yang, Eui-Hyeok

2009-01-01

A novel calibration technique has been developed for lateral force microscopy (LFM). Typically, special preparation of the atomic force microscope (AFM) cantilever or a substrate is required for LFM calibration. The new calibration technique reported in this paper greatly reduces the required preparation processes by simply scanning over a rigid step and measuring the response of the AFM photodiode in the normal and lateral directions. When an AFM tip touches a step while scanning, the tip experiences a reaction force from the step edge, and the amount of torsion can be estimated based on the ratio of the normal and torsional spring constants of an AFM cantilever. Therefore, the torsion can be calibrated using the measured response of the photodiode from the lateral movement of the AFM tip. This new calibration technique has been tested and confirmed by measuring Young's modulus of a nickel (Ni) nanowire

Study of equatorial Kelvin waves using the MST radar and radiosonde observations

Directory of Open Access Journals (Sweden)

P. Kishore

2005-06-01

Full Text Available In this paper an attempt has been made to study equatorial Kelvin waves using a high power coherent VHF radar located at Gadanki (13.5° N, 79.2° E, a tropical station in the Indian sub-continent. Simultaneous radiosonde observations taken from a nearby meteorological station located in Chennai (13.04° N, 80.17° E were also used to see the coherence in the observed structures. These data sets were analyzed to study the mean winds and equatorial waves in the troposphere and lower stratosphere. Equatorial waves with different periodicities were identified. In the present study, particular attention has been given to the fast Kelvin wave (6.5-day and slow Kelvin wave (16-day. Mean zonal wind structures were similar at both locations. The fast Kelvin wave amplitudes were somewhat similar in both observations and the maximum amplitude is about 8m/s. The phase profiles indicated a slow downward progression. The slow Kelvin wave (16-day amplitudes shown by the radiosonde measurements are a little larger than the radar derived amplitudes. The phase profiles showed downward phase progression and it translates into a vertical wavelength of ~10-12km. The radar and radiosonde derived amplitudes of fast and slow Kelvin waves are larger at altitudes near the tropopause (15-17km, where the mean wind attains westward maximum.

Nanomechanical properties of lithiated Si nanowires probed with atomic force microscopy

International Nuclear Information System (INIS)

Lee, Hyunsoo; Shin, Weonho; Choi, Jang Wook; Park, Jeong Young

2012-01-01

The nanomechanical properties of fully lithiated and pristine Si nanowires (NWs) deposited on a Si substrate were studied with atomic force microscopy (AFM). Si NWs were synthesized using the vapour-liquid-solid process on stainless-steel substrates using an Au catalyst. Fully lithiated Si NWs were obtained using the electrochemical method, followed by drop-casting on a Si substrate. The roughness of the Si NWs, which was derived from AFM images, is greater for the lithiated Si NWs than for the pristine Si NWs. Force spectroscopy was used to study the influence of lithiation on the tip-surface adhesion force. The lithiated Si NWs revealed a smaller tip-surface adhesion force than the Si substrate by a factor of two, while the adhesion force of the Si NWs is similar to that of the Si substrate. Young's modulus, obtained from the force-distance curve, also shows that the pristine Si NWs have a relatively higher value than the lithiated Si NWs due to the elastically soft and amorphous structures of the lithiated region. These results suggest that force spectroscopy can be used to probe the degree of lithiation at nanometer scale during the charging and discharging processes. (paper)

Bimodal atomic force microscopy imaging of isolated antibodies in air and liquids

International Nuclear Information System (INIS)

MartInez, N F; Lozano, J R; Herruzo, E T; Garcia, F; Garcia, R; Richter, C; Sulzbach, T

2008-01-01

We have developed a dynamic atomic force microscopy (AFM) method based on the simultaneous excitation of the first two flexural modes of the cantilever. The instrument, called a bimodal atomic force microscope, allows us to resolve the structural components of antibodies in both monomer and pentameric forms. The instrument operates in both high and low quality factor environments, i.e., air and liquids. We show that under the same experimental conditions, bimodal AFM is more sensitive to compositional changes than amplitude modulation AFM. By using theoretical and numerical methods, we study the material contrast sensitivity as well as the forces applied on the sample during bimodal AFM operation

Wave resistance calculation method combining Green functions based on Rankine and Kelvin source

Directory of Open Access Journals (Sweden)

LI Jingyu

2017-12-01

Full Text Available [Ojectives] At present, the Boundary Element Method(BEM of wave-making resistance mostly uses a model in which the velocity distribution near the hull is solved first, and the pressure integral is then calculated using the Bernoulli equation. However,the process of this model of wave-making resistance is complex and has low accuracy.[Methods] To address this problem, the present paper deduces a compound method for the quick calculation of ship wave resistance using the Rankine source Green function to solve the hull surface's source density, and combining the Lagally theorem concerning source point force calculation based on the Kelvin source Green function so as to solve the wave resistance. A case for the Wigley model is given.[Results] The results show that in contrast to the thin ship method of the linear wave resistance theorem, this method has higher precision, and in contrast to the method which completely uses the Kelvin source Green function, this method has better computational efficiency.[Conclusions] In general, the algorithm in this paper provides a compromise between precision and efficiency in wave-making resistance calculation.

Chemical bond imaging using higher eigenmodes of tuning fork sensors in atomic force microscopy

Science.gov (United States)

Ebeling, Daniel; Zhong, Qigang; Ahles, Sebastian; Chi, Lifeng; Wegner, Hermann A.; Schirmeisen, André

2017-05-01

We demonstrate the ability of resolving the chemical structure of single organic molecules using non-contact atomic force microscopy with higher normal eigenmodes of quartz tuning fork sensors. In order to achieve submolecular resolution, CO-functionalized tips at low temperatures are used. The tuning fork sensors are operated in ultrahigh vacuum in the frequency modulation mode by exciting either their first or second eigenmode. Despite the high effective spring constant of the second eigenmode (on the order of several tens of kN/m), the force sensitivity is sufficiently high to achieve atomic resolution above the organic molecules. This is observed for two different tuning fork sensors with different tip geometries (small tip vs. large tip). These results represent an important step towards resolving the chemical structure of single molecules with multifrequency atomic force microscopy techniques where two or more eigenmodes are driven simultaneously.

Restoration the domain structure from magnetic force microscopy image

Science.gov (United States)

Wu, Dongping; Lou, Yuanfu; Wei, Fulin; Wei, Dan

2012-04-01

This contribution gives an approximation method to calculate the stray field of the scanning plane from the magnetic force microscopy (MFM) force gradient image. Before calculation, a Butterworth low-pass filter has been used to remove a part of the noise of the image. The discrete Fourier transform (DFT) method has been used to calculate the magnetic potential of the film surface. It shows that the potential is not correct because the low-frequency noise has been enlarged. The approximation method gives a better result of the potential and proves that the MFM force gradient of the perpendicular component image also gives the perpendicular component of the stray field. Supposing that the distance between the tip and the sample is as small as near zero, the force gradient image also gives the magnetic charge distribution of the film surface. So if the orientation of the film from hysteresis loop is known, then the domain structure of the film can be determined. For perpendicular orientation, the absolution value of the perpendicular component of stray field gives the domain and domain wall position. For in-plane orientation, the absolution value of in-plane component of stray field gives the domain and domain wall position.

Concept for room temperature single-spin tunneling force microscopy with atomic spatial resolution

Science.gov (United States)

Payne, Adam

A study of a force detected single-spin magnetic resonance measurement concept with atomic spatial resolution is presented. The method is based upon electrostatic force detection of spin-selection rule controlled single electron tunneling between two electrically isolated paramagnetic states. Single-spin magnetic resonance detection is possible by measuring the force detected tunneling charge noise on and off spin resonance. Simulation results of this charge noise, based upon physical models of the tunneling and spin physics, are directly compared to measured atomic force microscopy (AFM) system noise. The results show that the approach could provide single-spin measurement of electrically isolated defect states with atomic spatial resolution at room temperature.

Atomic-resolution single-spin magnetic resonance detection concept based on tunneling force microscopy

Science.gov (United States)

Payne, A.; Ambal, K.; Boehme, C.; Williams, C. C.

2015-05-01

A study of a force detected single-spin magnetic resonance measurement concept with atomic spatial resolution is presented. The method is based upon electrostatic force detection of spin-selection rule controlled single-electron tunneling between two electrically isolated paramagnetic states. Single-spin magnetic resonance detection is possible by measuring the force detected tunneling charge noise on and off spin resonance. Simulation results of this charge noise, based upon physical models of the tunneling and spin physics, are directly compared to measured atomic force microscopy system noise. The results show that the approach could provide single-spin measurement of electrically isolated qubit states with atomic spatial resolution at room temperature.

Atomic force microscopy and transmission electron microscopy analyses of low-temperature laser welding of the cornea.

Science.gov (United States)

Matteini, Paolo; Sbrana, Francesca; Tiribilli, Bruno; Pini, Roberto

2009-07-01

Low-temperature laser welding of the cornea is a technique used to facilitate the closure of corneal cuts. The procedure consists of staining the wound with a chromophore (indocyanine green), followed by continuous wave irradiation with an 810 nm diode laser operated at low power densities (12-16 W/cm(2)), which induces local heating in the 55-65 degrees C range. In this study, we aimed to investigate the ultrastructural modifications in the extracellular matrix following laser welding of corneal wounds by means of atomic force microscopy and transmission electron microscopy. The results evidenced marked disorganization of the normal fibrillar assembly, although collagen appeared not to be denatured under the operating conditions we employed. The mechanism of low-temperature laser welding may be related to some structural modifications of the nonfibrillar extracellular components of the corneal stroma.

Magnetic force microscopy of thin film media for high density magnetic recording

NARCIS (Netherlands)

Porthun, Steffen; Porthun, S.; Abelmann, Leon; Lodder, J.C.

1998-01-01

This paper discusses various aspect of magnetic force microscopy (MFM) for use in the field of high density magnetic recording. After an introduction of the most important magnetic imaging techniques, an overview is given of the operation and theory of MFM. The developments in instrumentation, MFM

Elastic-properties measurement at high temperatures through contact resonance atomic force microscopy

DEFF Research Database (Denmark)

Marinello, Francesco; Pezzuolo, Andrea; Carmignato, Simone

2015-01-01

fast direct and non-destructive measurement of Young's modulus and related surface parameters.In this work an instrument set up for Contact Resonance Atomic Force Microscopy is proposed, where the sample with is coupled to a heating stage and a piezoelectric transducer directly vibrate the cantilever...

Attachment of trianglamines to silicon wafers, chiral recognition by chemical force microscopy

Czech Academy of Sciences Publication Activity Database

Hlinka, J.; Hodačová, Jana; Raehm, L.; Granier, M.; Ramonda, M.; Durand, J. O.

2010-01-01

Roč. 13, č. 4 (2010), s. 481-485 ISSN 1631-0748 R&D Projects: GA MŠk MEB020748 Institutional research plan: CEZ:AV0Z40550506 Keywords : trianglamines * chemical force microscopy * chiral recognition Subject RIV: CC - Organic Chemistry Impact factor: 1.600, year: 2010

Atomic force microscopy employed as the final imaging stage for soft x-ray contact microscopy

International Nuclear Information System (INIS)

Cotton, R.A.; Stead, A.D.; Ford, T.W.; Fletcher, J.H.

1993-01-01

Soft X-ray contact microscopy (SXCM) enables a high resolution image of a living biological specimen to be recorded in an X-ray sensitive photoresist at unity magnification. Until recently scanning electron microscopes (SEM) have been employed to obtain the final magnified image. Although this has been successful in producing many high resolution images, this method of viewing the resist has several disadvantages. Firstly, a metallic coating has to be applied to the resist surface to provide electrical conductivity, rendering further development of the resist impossible. Also, electron beam damage to the resist surface can occur, in addition to poor resolution and image quality. Atomic force microscopy (AFM) allows uncoated resists to be imaged at a superior resolution, without damage to the surface. The use of AFM is seen as a major advancement in SXCM. The advantages and disadvantages of the two technologies are discussed, with illustrations from recent studies of a wide variety of hydrated biological specimens imaged using SXCM

Magnetic anisotropy considerations in magnetic force microscopy studies of single superparamagnetic nanoparticles

International Nuclear Information System (INIS)

Nocera, Tanya M; Agarwal, Gunjan; Chen Jun; Murray, Christopher B

2012-01-01

In recent years, superparamagnetic nanoparticles (SPNs) have become increasingly important in applications ranging from solid state memory devices to biomedical diagnostic and therapeutic tools. However, detection and characterization of the small and unstable magnetic moment of an SPN at the single particle level remains a challenge. Further, depending on their physical shape, crystalline structure or orientation, SPNs may also possess magnetic anisotropy, which can govern the extent to which their magnetic moments can align with an externally applied magnetic field. Here, we demonstrate how we can exploit the magnetic anisotropy of SPNs to enable uniform, highly-sensitive detection of single SPNs using magnetic force microscopy (MFM) in ambient air. Superconducting quantum interference device magnetometry and analytical transmission electron microscopy techniques are utilized to characterize the collective magnetic behavior, morphology and composition of the SPNs. Our results show how the consideration of magnetic anisotropy can enhance the ability of MFM to detect single SPNs at ambient room temperature with high force sensitivity and spatial resolution. (paper)

Electron microscopy of intermediate filaments: teaming up with atomic force and confocal laser scanning microscopy.

Science.gov (United States)

Kreplak, Laurent; Richter, Karsten; Aebi, Ueli; Herrmann, Harald

2008-01-01

Intermediate filaments (IFs) were originally discovered and defined by electron microscopy in myoblasts. In the following it was demonstrated and confirmed that they constitute, in addition to microtubules and microfilaments, a third independent, general filament system in the cytoplasm of most metazoan cells. In contrast to the other two systems, IFs are present in cells in two principally distinct cytoskeletal forms: (i) extended and free-running filament arrays in the cytoplasm that are integrated into the cytoskeleton by associated proteins of the plakin type; and (ii) a membrane- and chromatin-bound thin 'lamina' of a more or less regular network of interconnected filaments made from nuclear IF proteins, the lamins, which differ in several important structural aspects from cytoplasmic IF proteins. In man, more than 65 genes code for distinct IF proteins that are expressed during embryogenesis in various routes of differentiation in a tightly controlled manner. IF proteins exhibit rather limited sequence identity implying that the different types of IFs have distinct biochemical properties. Hence, to characterize the structural properties of the various IFs, in vitro assembly regimes have been developed in combination with different visualization methods such as transmission electron microscopy of fixed and negatively stained samples as well as methods that do not use staining such as scanning transmission electron microscopy (STEM) and cryoelectron microscopy as well as atomic force microscopy. Moreover, with the generation of both IF-type specific antibodies and chimeras of fluorescent proteins and IF proteins, it has become possible to investigate the subcellular organization of IFs by correlative fluorescence and electron microscopic methods. The combination of these powerful methods should help to further develop our understanding of nuclear architecture, in particular how nuclear subcompartments are organized and in which way lamins are involved.

Stratum corneum lipid organization as observed by atomic force, confocal and two-photon excitation fluorescence microscopy

DEFF Research Database (Denmark)

Norlén, Lars; Plasencia Gil, Maria Inés; Bagatolli, Luis

2008-01-01

-related biophysical techniques (e.g. atomic force microscopy and confocal/two-photon excitation fluorescence microscopy), it was recently shown that reconstituted membranes composed of extracted decontaminated human stratum corneum lipids do not form a fluid phase, but exclusively a single-gel phase that segregates...

Mechanical properties of cellulose nanomaterials studied by contact resonance atomic force microscopy

Science.gov (United States)

Ryan Wagner; Robert J. Moon; Arvind Raman

2016-01-01

Quantification of the mechanical properties of cellulose nanomaterials is key to the development of new cellulose nanomaterial based products. Using contact resonance atomic force microscopy we measured and mapped the transverse elastic modulus of three types of cellulosic nanoparticles: tunicate cellulose nanocrystals, wood cellulose nanocrystals, and wood cellulose...

Nanophotonic force microscopy: characterizing particle-surface interactions using near-field photonics.

Science.gov (United States)

Schein, Perry; Kang, Pilgyu; O'Dell, Dakota; Erickson, David

2015-02-11

Direct measurements of particle-surface interactions are important for characterizing the stability and behavior of colloidal and nanoparticle suspensions. Current techniques are limited in their ability to measure pico-Newton scale interaction forces on submicrometer particles due to signal detection limits and thermal noise. Here we present a new technique for making measurements in this regime, which we refer to as nanophotonic force microscopy. Using a photonic crystal resonator, we generate a strongly localized region of exponentially decaying, near-field light that allows us to confine small particles close to a surface. From the statistical distribution of the light intensity scattered by the particle we are able to map out the potential well of the trap and directly quantify the repulsive force between the nanoparticle and the surface. As shown in this Letter, our technique is not limited by thermal noise, and therefore, we are able to resolve interaction forces smaller than 1 pN on dielectric particles as small as 100 nm in diameter.

Accurate spring constant calibration for very stiff atomic force microscopy cantilevers

Energy Technology Data Exchange (ETDEWEB)

Grutzik, Scott J.; Zehnder, Alan T. [Field of Theoretical and Applied Mechanics, Cornell University, Ithaca, New York 14853 (United States); Gates, Richard S.; Gerbig, Yvonne B.; Smith, Douglas T.; Cook, Robert F. [Nanomechanical Properties Group, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2013-11-15

There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is required. In most cases, the forces of interest are very small, thus compliant cantilevers are used. A number of methods have been developed that are well suited to measuring low stiffness values. However, in some cases a cantilever with much greater stiffness is required. Thus, a direct, traceable method for calibrating very stiff (approximately 200 N/m) cantilevers is presented here. The method uses an instrumented and calibrated nanoindenter to determine the stiffness of a reference cantilever. This reference cantilever is then used to measure the stiffness of a number of AFM test cantilevers. This method is shown to have much smaller uncertainty than previously proposed methods. An example application to fracture testing of nanoscale silicon beam specimens is included.

Accurate spring constant calibration for very stiff atomic force microscopy cantilevers

International Nuclear Information System (INIS)

Grutzik, Scott J.; Zehnder, Alan T.; Gates, Richard S.; Gerbig, Yvonne B.; Smith, Douglas T.; Cook, Robert F.

2013-01-01

There are many atomic force microscopy (AFM) applications that rely on quantifying the force between the AFM cantilever tip and the sample. The AFM does not explicitly measure force, however, so in such cases knowledge of the cantilever stiffness is required. In most cases, the forces of interest are very small, thus compliant cantilevers are used. A number of methods have been developed that are well suited to measuring low stiffness values. However, in some cases a cantilever with much greater stiffness is required. Thus, a direct, traceable method for calibrating very stiff (approximately 200 N/m) cantilevers is presented here. The method uses an instrumented and calibrated nanoindenter to determine the stiffness of a reference cantilever. This reference cantilever is then used to measure the stiffness of a number of AFM test cantilevers. This method is shown to have much smaller uncertainty than previously proposed methods. An example application to fracture testing of nanoscale silicon beam specimens is included

Lipid domain formation and ligand-receptor distribution in lipid bilayer membranes investigated by atomic force microscopy

DEFF Research Database (Denmark)

Kaasgaard, Thomas; Mouritsen, O.G.; Jørgensen, K.

2002-01-01

A novel experimental technique, based on atomic force microscopy (AFM), is proposed to visualize the lateral organization of membrane systems in the nanometer range. The technique involves the use of a ligand-receptor pair, biotin-avidin, which introduces a height variation on a solid-supported l......A novel experimental technique, based on atomic force microscopy (AFM), is proposed to visualize the lateral organization of membrane systems in the nanometer range. The technique involves the use of a ligand-receptor pair, biotin-avidin, which introduces a height variation on a solid...

Influence of Poisson's ratio variation on lateral spring constant of atomic force microscopy cantilevers

International Nuclear Information System (INIS)

Yeh, M.-K.; Tai, N.-Ha; Chen, B.-Y.

2008-01-01

Atomic force microscopy (AFM) can be used to measure the surface morphologies and the mechanical properties of nanostructures. The force acting on the AFM cantilever can be obtained by multiplying the spring constant of AFM cantilever and the corresponding deformation. To improve the accuracy of force experiments, the spring constant of AFM cantilever must be calibrated carefully. Many methods, such as theoretical equations, the finite element method, and the use of reference cantilever, were reported to obtain the spring constant of AFM cantilevers. For the cantilever made of single crystal, the Poisson's ratio varies with different cantilever-crystal angles. In this paper, the influences of Poisson's ratio variation on the lateral spring constant and axial spring constant of rectangular and V-shaped AFM cantilevers, with different tilt angles and normal forces, were investigated by the finite element analysis. When the cantilever's tilt angle is 20 deg. and the Poisson's ratio varies from 0.02 to 0.4, the finite element results show that the lateral spring constants decrease 11.75% for the rectangular cantilever with 1 μN landing force and decrease 18.60% for the V-shaped cantilever with 50 nN landing force, respectively. The influence of Poisson's ratio variation on axial spring constant is less than 3% for both rectangular and V-shaped cantilevers. As the tilt angle increases, the axial spring constants for rectangular and V-shaped cantilevers decrease substantially. The results obtained can be used to improve the accuracy of the lateral force measurement when using atomic force microscopy

Electrostatic force microscopy with a self-sensing piezoresistive cantilever

International Nuclear Information System (INIS)

Pi, U. H.; Kye, J. I.; Shin, S.; Khim, Z. G.; Hong, J. W.; Yoon, S.

2003-01-01

We present a new method for electrostatic force microscopy (EFM) using a piezoresistive cantilever instead of the conventional cantilever with an optical detector. In EFM with a piezoresistive cantilever, the electrostatic force between the tip and the sample is monitored by sensing the change in the resistance of the piezoresistive cantilever at a frequency of several tens of kHz. A large stray capacitance effect can be rejected by using an appropriate phase tuning of the phase-sensitive detection. We observed the ferroelectric domain images of a triglycine sulfate single crystal. We could also write fine patterns on a lead-zirconate-titanate (PZT) thin film through domain reversal by applying various dc voltages between the tip and the sample. We suggest that the EFM technique using a self-sensing and self-actuating piezoresistive cantilever can be applied to a high-density data storage field

Atomic force microscopy-based repeated machining theory for nanochannels on silicon oxide surfaces

Energy Technology Data Exchange (ETDEWEB)

Wang, Z.Q., E-mail: wangzhiqian@sia.cn [State Key Laboratory of Robotics, Shenyang Institute of Automation, CAS, Shenyang 110016 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Jiao, N.D. [State Key Laboratory of Robotics, Shenyang Institute of Automation, CAS, Shenyang 110016 (China); Tung, S. [Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Dong, Z.L. [State Key Laboratory of Robotics, Shenyang Institute of Automation, CAS, Shenyang 110016 (China)

2011-02-01

The atomic force microscopy (AFM)-based repeated nanomachining of nanochannels on silicon oxide surfaces is investigated both theoretically and experimentally. The relationships of the initial nanochannel depth vs. final nanochannel depth at a normal force are systematically studied. Using the derived theory and simulation results, the final nanochannel depth can be predicted easily. Meanwhile, if a nanochannel with an expected depth needs to be machined, a right normal force can be selected simply and easily in order to decrease the wear of the AFM tip. The theoretical analysis and simulation results can be effectively used for AFM-based fabrication of nanochannels.

Robust operation and performance of integrated carbon nanotubes atomic force microscopy probes

International Nuclear Information System (INIS)

Rius, G; Clark, I T; Yoshimura, M

2013-01-01

We present a complete characterization of carbon nanotubes-atomic force microscopy (CNT-AFM) probes to evaluate the cantilever operation and advanced properties originating from the CNTs. The fabrication consists of silicon probes tip-functionalized with multiwalled CNTs by microwave plasma enhanced chemical vapor deposition. A dedicated methodology has been defined to evaluate the effect of CNT integration into the Si cantilevers. The presence of the CNTs provides enhanced capability for sensing and durability, as demonstrated using dynamic and static modes, e.g. imaging, indentation and force/current characterization.

Combined short scale roughness and surface dielectric function gradient effects on the determination of tip-sample force in atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Gusso, André, E-mail: gusso@metal.eeimvr.uff.br [Departamento de Ciências Exatas-EEIMVR, Universidade Federal Fluminense, Volta Redonda, RJ 27255-125 (Brazil)

2013-11-11

The contribution of tip roughness to the van der Waals force between an atomic force microscopy probe tip and the sample is calculated using the multilayer effective medium model, which allows us to consider the relevant case of roughness characterized by correlation length and amplitude in the nanometer scale. The effect of the surface dielectric function gradient is incorporated in the tip-sample force model. It is concluded that for rms roughness in the few nanometers range the effect of short scale tip roughness is quite significant.

Optimizing atomic force microscopy for characterization of diamond-protein interfaces

Czech Academy of Sciences Publication Activity Database

Rezek, Bohuslav; Ukraintsev, Egor; Kromka, Alexander

2011-01-01

Roč. 6, Apr. (2011), 337/1-337/10 ISSN 1931-7573 R&D Projects: GA MŠk(CZ) LC06040; GA ČR(CZ) GAP108/11/0794; GA AV ČR KAN400100701; GA MŠk LC510 Institutional research plan: CEZ:AV0Z10100521 Keywords : atomic force microscopy (AFM) * nanocrystalline diamond * oxygen-terminated diamond * hydrogen-terminated diamond * proteins * fetal bovine serum (FBS) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.726, year: 2011

Molecular magnetic hysteresis at 60 kelvin in dysprosocenium

Science.gov (United States)

Goodwin, Conrad A. P.; Ortu, Fabrizio; Reta, Daniel; Chilton, Nicholas F.; Mills, David P.

2017-08-01

Lanthanides have been investigated extensively for potential applications in quantum information processing and high-density data storage at the molecular and atomic scale. Experimental achievements include reading and manipulating single nuclear spins, exploiting atomic clock transitions for robust qubits and, most recently, magnetic data storage in single atoms. Single-molecule magnets exhibit magnetic hysteresis of molecular origin—a magnetic memory effect and a prerequisite of data storage—and so far lanthanide examples have exhibited this phenomenon at the highest temperatures. However, in the nearly 25 years since the discovery of single-molecule magnets, hysteresis temperatures have increased from 4 kelvin to only about 14 kelvin using a consistent magnetic field sweep rate of about 20 oersted per second, although higher temperatures have been achieved by using very fast sweep rates (for example, 30 kelvin with 200 oersted per second). Here we report a hexa-tert-butyldysprosocenium complex—[Dy(Cpttt)2][B(C6F5)4], with Cpttt = {C5H2tBu3-1,2,4} and tBu = C(CH3)3—which exhibits magnetic hysteresis at temperatures of up to 60 kelvin at a sweep rate of 22 oersted per second. We observe a clear change in the relaxation dynamics at this temperature, which persists in magnetically diluted samples, suggesting that the origin of the hysteresis is the localized metal-ligand vibrational modes that are unique to dysprosocenium. Ab initio calculations of spin dynamics demonstrate that magnetic relaxation at high temperatures is due to local molecular vibrations. These results indicate that, with judicious molecular design, magnetic data storage in single molecules at temperatures above liquid nitrogen should be possible.

Brown algal morphogenesis: Atomic Force Microscopy as a tool to study the role of mechanical forces

Directory of Open Access Journals (Sweden)

Benoit eTesson

2014-09-01

Full Text Available Over the last few years, a growing interest has been directed toward the use of macroalgae as a source of energy, food and molecules for the cosmetic and pharmaceutical industries. Besides this, macroalgal development remains poorly understood compared to other multicellular organisms. Brown algae (Phaeophyceae form a monophyletic lineage of usually large multicellular algae which evolved independently from land plants. In their environment, they are subjected to strong mechanical forces (current, waves and tide, in response to which they modify rapidly and reversibly their morphology. Because of their specific cellular features (cell wall composition, cytoskeleton organization, deciphering how they cope with these forces might help discover new control mechanisms of cell wall softening and cellulose synthesis. Despite the current scarcity in knowledge on brown algal cell wall dynamics and protein composition, we will illustrate, in the light of methods adapted to Ectocarpus siliculosus, to what extent atomic force microscopy can contribute to advance this field of investigation.

Surface structure investigations using noncontact atomic force microscopy

International Nuclear Information System (INIS)

Kolodziej, J.J.; Such, B.; Goryl, M.; Krok, F.; Piatkowski, P.; Szymonski, M.

2006-01-01

Surfaces of several A III B V compound semiconductors (InSb, GaAs, InP, InAs) of the (0 0 1) orientation have been studied with noncontact atomic force microscopy (NC-AFM). Obtained atomically resolved patterns have been compared with structural models available in the literature. It is shown that NC-AFM is an efficient tool for imaging complex surface structures in real space. It is also demonstrated that the recent structural models of III-V compound surfaces provide a sound base for interpretation of majority of features present in recorded patterns. However, there are also many new findings revealed by the NC-AFM method that is still new experimental technique in the context of surface structure determination

Photolithographic Polymerization of Diacetylene-Containing Phospholipid Bilayers Studied by Multimode Atomic Force Microscopy

NARCIS (Netherlands)

Morigaki, Kenichi; Schönherr, Holger; Frank, Curtis W.; Knoll, Wolfgang

2003-01-01

Photopolymerization of the diacetylene-containing phospholipid 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (1) in substrate-supported planar lipid bilayers (SPBs) has been studied by using multimode atomic force microscopy (AFM). Monolayers and bilayers of 1 have been transferred onto

Multifarious applications of atomic force microscopy in forensic science investigations.

Science.gov (United States)

Pandey, Gaurav; Tharmavaram, Maithri; Rawtani, Deepak; Kumar, Sumit; Agrawal, Y

2017-04-01

Forensic science is a wide field comprising of several subspecialties and uses methods derived from natural sciences for finding criminals and other evidence valid in a legal court. A relatively new area; Nano-forensics brings a new era of investigation in forensic science in which instantaneous results can be produced that determine various agents such as explosive gasses, biological agents and residues in different crime scenes and terrorist activity investigations. This can be achieved by applying Nanotechnology and its associated characterization techniques in forensic sciences. Several characterization techniques exist in Nanotechnology and nano-analysis is one such technique that is used in forensic science which includes Electron microscopes (EM) like Transmission (TEM) and Scanning (SEM), Raman microscopy (Micro -Raman) and Scanning Probe Microscopes (SPMs) like Atomic Force Microscope (AFM). Atomic force microscopy enables surface characterization of different materials by examining their morphology and mechanical properties. Materials that are immeasurable such as hair, body fluids, textile fibers, documents, polymers, pressure sensitive adhesives (PSAs), etc. are often encountered during forensic investigations. This review article will mainly focus on the use of AFM in the examination of different evidence such as blood stains, forged documents, human hair samples, ammunitions, explosives, and other such applications in the field of Forensic Science. Copyright © 2017 Elsevier B.V. All rights reserved.

Atomic Force Microscopy: A Powerful Tool to Address Scaffold Design in Tissue Engineering.

Science.gov (United States)

Marrese, Marica; Guarino, Vincenzo; Ambrosio, Luigi

2017-02-13

Functional polymers currently represent a basic component of a large range of biological and biomedical applications including molecular release, tissue engineering, bio-sensing and medical imaging. Advancements in these fields are driven by the use of a wide set of biodegradable polymers with controlled physical and bio-interactive properties. In this context, microscopy techniques such as Atomic Force Microscopy (AFM) are emerging as fundamental tools to deeply investigate morphology and structural properties at micro and sub-micrometric scale, in order to evaluate the in time relationship between physicochemical properties of biomaterials and biological response. In particular, AFM is not only a mere tool for screening surface topography, but may offer a significant contribution to understand surface and interface properties, thus concurring to the optimization of biomaterials performance, processes, physical and chemical properties at the micro and nanoscale. This is possible by capitalizing the recent discoveries in nanotechnologies applied to soft matter such as atomic force spectroscopy to measure surface forces through force curves. By tip-sample local interactions, several information can be collected such as elasticity, viscoelasticity, surface charge densities and wettability. This paper overviews recent developments in AFM technology and imaging techniques by remarking differences in operational modes, the implementation of advanced tools and their current application in biomaterials science, in terms of characterization of polymeric devices in different forms (i.e., fibres, films or particles).

Atomic Force Microscopy: A Powerful Tool to Address Scaffold Design in Tissue Engineering

Directory of Open Access Journals (Sweden)

Marica Marrese

2017-02-01

Full Text Available Functional polymers currently represent a basic component of a large range of biological and biomedical applications including molecular release, tissue engineering, bio-sensing and medical imaging. Advancements in these fields are driven by the use of a wide set of biodegradable polymers with controlled physical and bio-interactive properties. In this context, microscopy techniques such as Atomic Force Microscopy (AFM are emerging as fundamental tools to deeply investigate morphology and structural properties at micro and sub-micrometric scale, in order to evaluate the in time relationship between physicochemical properties of biomaterials and biological response. In particular, AFM is not only a mere tool for screening surface topography, but may offer a significant contribution to understand surface and interface properties, thus concurring to the optimization of biomaterials performance, processes, physical and chemical properties at the micro and nanoscale. This is possible by capitalizing the recent discoveries in nanotechnologies applied to soft matter such as atomic force spectroscopy to measure surface forces through force curves. By tip-sample local interactions, several information can be collected such as elasticity, viscoelasticity, surface charge densities and wettability. This paper overviews recent developments in AFM technology and imaging techniques by remarking differences in operational modes, the implementation of advanced tools and their current application in biomaterials science, in terms of characterization of polymeric devices in different forms (i.e., fibres, films or particles.

Imaging of Au nanoparticles deeply buried in polymer matrix by various atomic force microscopy techniques

International Nuclear Information System (INIS)

Kimura, Kuniko; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

2013-01-01

Recently, some papers reported successful imaging of subsurface features using atomic force microscopy (AFM). Some theoretical studies have also been presented, however the imaging mechanisms are not fully understood yet. In the preceeding papers, imaging of deeply buried nanometer-scale features has been successful only if they were buried in a soft matrix. In this paper, subsurface features (Au nanoparticles) buried in a soft polymer matrix were visualized. To elucidate the imaging mechanisms, various AFM techniques; heterodyne force microscopy, ultrasonic atomic force microscopy (UAFM), 2nd-harmonic UAFM and force modulation microscopy (FMM) were employed. The particles buried under 960 nm from the surface were successfully visualized which has never been achieved. The results elucidated that it is important for subsurface imaging to choose a cantilever with a suitable stiffness range for a matrix. In case of using the most suitable cantilever, the nanoparticles were visualized using every technique shown above except for FMM. The experimental results suggest that the subsurface features buried in a soft matrix with a depth of at least 1 µm can affect the local viscoelasticity (mainly viscosity) detected as the variation of the amplitude and phase of the tip oscillation on the surface. This phenomenon presumably makes it possible to visualize such deeply buried nanometer-scale features in a soft matrix. - Highlights: • We visualized subsurface features buried in soft matrix, and investigated its imaging mechanism. • AFM techniques; UAFM, FMM, HFM and 2nd-harmonic UAFM were applied to elucidate the mechanism. • Au nanoparticles buried under 960 nm from surface were visualized, which has never been achieved. • Imaging at contact resonance using a cantilever of suitable stiffness is important. • Subsurface features in a soft matrix affect surface viscoelasticity, which are detected by AFM

Molecular Processes Studied at a Single-Molecule Level Using DNA Origami Nanostructures and Atomic Force Microscopy

Directory of Open Access Journals (Sweden)

Ilko Bald

2014-09-01

Full Text Available DNA origami nanostructures allow for the arrangement of different functionalities such as proteins, specific DNA structures, nanoparticles, and various chemical modifications with unprecedented precision. The arranged functional entities can be visualized by atomic force microscopy (AFM which enables the study of molecular processes at a single-molecular level. Examples comprise the investigation of chemical reactions, electron-induced bond breaking, enzymatic binding and cleavage events, and conformational transitions in DNA. In this paper, we provide an overview of the advances achieved in the field of single-molecule investigations by applying atomic force microscopy to functionalized DNA origami substrates.

Quantitative assessment of contact and non-contact lateral force calibration methods for atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Tran Khac, Bien Cuong; Chung, Koo-Hyun, E-mail: khchung@ulsan.ac.kr

2016-02-15

Atomic Force Microscopy (AFM) has been widely used for measuring friction force at the nano-scale. However, one of the key challenges faced by AFM researchers is to calibrate an AFM system to interpret a lateral force signal as a quantifiable force. In this study, five rectangular cantilevers were used to quantitatively compare three different lateral force calibration methods to demonstrate the legitimacy and to establish confidence in the quantitative integrity of the proposed methods. The Flat-Wedge method is based on a variation of the lateral output on a surface with flat and changing slopes, the Multi-Load Pivot method is based on taking pivot measurements at several locations along the cantilever length, and the Lateral AFM Thermal-Sader method is based on determining the optical lever sensitivity from the thermal noise spectrum of the first torsional mode with a known torsional spring constant from the Sader method. The results of the calibration using the Flat-Wedge and Multi-Load Pivot methods were found to be consistent within experimental uncertainties, and the experimental uncertainties of the two methods were found to be less than 15%. However, the lateral force sensitivity determined by the Lateral AFM Thermal-Sader method was found to be 8–29% smaller than those obtained from the other two methods. This discrepancy decreased to 3–19% when the torsional mode correction factor for an ideal cantilever was used, which suggests that the torsional mode correction should be taken into account to establish confidence in Lateral AFM Thermal-Sader method. - Highlights: • Quantitative assessment of three lateral force calibration methods for AFM. • Advantages and disadvantages of three different lateral force calibration method. • Implementation of Multi-Load Pivot method as non-contact calibration technique. • The torsional mode correction for Lateral AFM Thermal-Sader method.

Quantitative assessment of contact and non-contact lateral force calibration methods for atomic force microscopy

International Nuclear Information System (INIS)

Tran Khac, Bien Cuong; Chung, Koo-Hyun

2016-01-01

Atomic Force Microscopy (AFM) has been widely used for measuring friction force at the nano-scale. However, one of the key challenges faced by AFM researchers is to calibrate an AFM system to interpret a lateral force signal as a quantifiable force. In this study, five rectangular cantilevers were used to quantitatively compare three different lateral force calibration methods to demonstrate the legitimacy and to establish confidence in the quantitative integrity of the proposed methods. The Flat-Wedge method is based on a variation of the lateral output on a surface with flat and changing slopes, the Multi-Load Pivot method is based on taking pivot measurements at several locations along the cantilever length, and the Lateral AFM Thermal-Sader method is based on determining the optical lever sensitivity from the thermal noise spectrum of the first torsional mode with a known torsional spring constant from the Sader method. The results of the calibration using the Flat-Wedge and Multi-Load Pivot methods were found to be consistent within experimental uncertainties, and the experimental uncertainties of the two methods were found to be less than 15%. However, the lateral force sensitivity determined by the Lateral AFM Thermal-Sader method was found to be 8–29% smaller than those obtained from the other two methods. This discrepancy decreased to 3–19% when the torsional mode correction factor for an ideal cantilever was used, which suggests that the torsional mode correction should be taken into account to establish confidence in Lateral AFM Thermal-Sader method. - Highlights: • Quantitative assessment of three lateral force calibration methods for AFM. • Advantages and disadvantages of three different lateral force calibration method. • Implementation of Multi-Load Pivot method as non-contact calibration technique. • The torsional mode correction for Lateral AFM Thermal-Sader method.

Analysis of dynamic cantilever behavior in tapping mode atomic force microscopy.

Science.gov (United States)

Deng, Wenqi; Zhang, Guang-Ming; Murphy, Mark F; Lilley, Francis; Harvey, David M; Burton, David R

2015-10-01

Tapping mode atomic force microscopy (AFM) provides phase images in addition to height and amplitude images. Although the behavior of tapping mode AFM has been investigated using mathematical modeling, comprehensive understanding of the behavior of tapping mode AFM still poses a significant challenge to the AFM community, involving issues such as the correct interpretation of the phase images. In this paper, the cantilever's dynamic behavior in tapping mode AFM is studied through a three dimensional finite element method. The cantilever's dynamic displacement responses are firstly obtained via simulation under different tip-sample separations, and for different tip-sample interaction forces, such as elastic force, adhesion force, viscosity force, and the van der Waals force, which correspond to the cantilever's action upon various different representative computer-generated test samples. Simulated results show that the dynamic cantilever displacement response can be divided into three zones: a free vibration zone, a transition zone, and a contact vibration zone. Phase trajectory, phase shift, transition time, pseudo stable amplitude, and frequency changes are then analyzed from the dynamic displacement responses that are obtained. Finally, experiments are carried out on a real AFM system to support the findings of the simulations. © 2015 Wiley Periodicals, Inc.

Lateral force calibration in atomic force microscopy: A new lateral force calibration method and general guidelines for optimization

International Nuclear Information System (INIS)

Cannara, Rachel J.; Eglin, Michael; Carpick, Robert W.

2006-01-01

Proper force calibration is a critical step in atomic and lateral force microscopies (AFM/LFM). The recently published torsional Sader method [C. P. Green et al., Rev. Sci. Instrum. 75, 1988 (2004)] facilitates the calculation of torsional spring constants of rectangular AFM cantilevers by eliminating the need to obtain information or make assumptions regarding the cantilever's material properties and thickness, both of which are difficult to measure. Complete force calibration of the lateral signal in LFM requires measurement of the lateral signal deflection sensitivity as well. In this article, we introduce a complete lateral force calibration procedure that employs the torsional Sader method and does not require making contact between the tip and any sample. In this method, a colloidal sphere is attached to a 'test' cantilever of the same width, but different length and material as the 'target' cantilever of interest. The lateral signal sensitivity is calibrated by loading the colloidal sphere laterally against a vertical sidewall. The signal sensitivity for the target cantilever is then corrected for the tip length, total signal strength, and in-plane bending of the cantilevers. We discuss the advantages and disadvantages of this approach in comparison with the other established lateral force calibration techniques, and make a direct comparison with the 'wedge' calibration method. The methods agree to within 5%. The propagation of errors is explicitly considered for both methods and the sources of disagreement discussed. Finally, we show that the lateral signal sensitivity is substantially reduced when the laser spot is not centered on the detector

Imaging modes of atomic force microscopy for application in molecular and cell biology

NARCIS (Netherlands)

Dufrêne, Yves F.; Ando, Toshio; Garcia, Ricardo; Alsteens, David; Martinez-Martin, David; Engel, A.H.; Gerber, Christoph; Müller, Daniel J.

2017-01-01

Atomic force microscopy (AFM) is a powerful, multifunctional imaging platform that allows biological samples, from single molecules to living cells, to be visualized and manipulated. Soon after the instrument was invented, it was recognized that in order to maximize the opportunities of AFM

Determination of electrostatic force and its characteristics based on phase difference by amplitude modulation atomic force microscopy

Science.gov (United States)

Wang, Kesheng; Cheng, Jia; Yao, Shiji; Lu, Yijia; Ji, Linhong; Xu, Dengfeng

2016-12-01

Electrostatic force measurement at the micro/nano scale is of great significance in science and engineering. In this paper, a reasonable way of applying voltage is put forward by taking an electrostatic chuck in a real integrated circuit manufacturing process as a sample, applying voltage in the probe and the sample electrode, respectively, and comparing the measurement effect of the probe oscillation phase difference by amplitude modulation atomic force microscopy. Based on the phase difference obtained from the experiment, the quantitative dependence of the absolute magnitude of the electrostatic force on the tip-sample distance and applied voltage is established by means of theoretical analysis and numerical simulation. The results show that the varying characteristics of the electrostatic force with the distance and voltage at the micro/nano scale are similar to those at the macroscopic scale. Electrostatic force gradually decays with increasing distance. Electrostatic force is basically proportional to the square of applied voltage. Meanwhile, the applicable conditions of the above laws are discussed. In addition, a comparison of the results in this paper with the results of the energy dissipation method shows the two are consistent in general. The error decreases with increasing distance, and the effect of voltage on the error is small.

Investigation of integrin expression on the surface of osteoblast-like cells by atomic force microscopy

International Nuclear Information System (INIS)

Caneva Soumetz, Federico; Saenz, Jose F.; Pastorino, Laura; Ruggiero, Carmelina; Nosi, Daniele; Raiteri, Roberto

2010-01-01

The transforming growth factor β1 (TGF-β1) is a human cytokine which has been demonstrated to modulate cell surface integrin repertoire. In this work integrin expression in response to TGF-β1 stimulation has been investigated on the surface of human osteoblast-like cells. We used atomic force microscopy (AFM) and confocal laser scanning microscopy to assess integrin expression and to evaluate their distribution over the dorsal side of the plasma membrane. AFM probes have been covalently functionalised with monoclonal antibodies specific to the β1 integrin subunit. Force curves have been collected in order to obtain maps of the interaction between the immobilized antibody and the respective cell membrane receptors. Adhesion peaks have been automatically detected by means of an ad hoc developed data analysis software. The specificity of the detected interactions has been assessed by adding free antibody in the solution and monitoring the dramatic decrease in the recorded interactions. In addition, the effect of TGF-β1 treatment on both the fluorescence signal and the adhesion events has been tested. The level of expression of the β1 integrin subunit was enhanced by TGF-β1. As a further analysis, the adhesion force of the single living cells to the substrate was measured by laterally pushing the cell with the AFM tip and measuring the force necessary to displace it. The treatment with TGF-β1 resulted in a decrease of the cell/substrate adhesion force. Results obtained by AFM have been validated by confocal laser scanning microscopy thus demonstrating the high potential of the AFM technique for the investigation of cell surface receptors distribution and trafficking at the nanoscale.

Investigation of integrin expression on the surface of osteoblast-like cells by atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Caneva Soumetz, Federico [Department of Communication, Computer and System Sciences, University of Genova, Via Opera Pia, 13-16145 Genova (Italy); Saenz, Jose F. [Biophysical and Electronic Engineering Department, University of Genova, Via All' Opera Pia 11a, 16145 Genova (Italy); Pastorino, Laura; Ruggiero, Carmelina [Department of Communication, Computer and System Sciences, University of Genova, Via Opera Pia, 13-16145 Genova (Italy); Nosi, Daniele [Department of Anatomy, Histology and Forensic Medicine, Bio-photonic Laboratory, University of Florence, viale Morgagni, 85 Firenze, CAP 50134 Florence (Italy); Raiteri, Roberto, E-mail: rr@unige.it [Biophysical and Electronic Engineering Department, University of Genova, Via All' Opera Pia 11a, 16145 Genova (Italy)

2010-03-15

The transforming growth factor {beta}1 (TGF-{beta}1) is a human cytokine which has been demonstrated to modulate cell surface integrin repertoire. In this work integrin expression in response to TGF-{beta}1 stimulation has been investigated on the surface of human osteoblast-like cells. We used atomic force microscopy (AFM) and confocal laser scanning microscopy to assess integrin expression and to evaluate their distribution over the dorsal side of the plasma membrane. AFM probes have been covalently functionalised with monoclonal antibodies specific to the {beta}1 integrin subunit. Force curves have been collected in order to obtain maps of the interaction between the immobilized antibody and the respective cell membrane receptors. Adhesion peaks have been automatically detected by means of an ad hoc developed data analysis software. The specificity of the detected interactions has been assessed by adding free antibody in the solution and monitoring the dramatic decrease in the recorded interactions. In addition, the effect of TGF-{beta}1 treatment on both the fluorescence signal and the adhesion events has been tested. The level of expression of the {beta}1 integrin subunit was enhanced by TGF-{beta}1. As a further analysis, the adhesion force of the single living cells to the substrate was measured by laterally pushing the cell with the AFM tip and measuring the force necessary to displace it. The treatment with TGF-{beta}1 resulted in a decrease of the cell/substrate adhesion force. Results obtained by AFM have been validated by confocal laser scanning microscopy thus demonstrating the high potential of the AFM technique for the investigation of cell surface receptors distribution and trafficking at the nanoscale.

Atomic force microscopy characterization of the surface wettability of natural fibres

International Nuclear Information System (INIS)

Pietak, Alexis; Korte, Sandra; Tan, Emelyn; Downard, Alison; Staiger, Mark P.

2007-01-01

Natural fibres represent a readily available source of ecologically friendly and inexpensive reinforcement in composites with degradable thermoplastics, however chemical treatments of fibres are required to prepare feasible composites. It is desirable to characterize the surface wettability of fibres after chemical treatment as the polarity of cellulose-based fibres influences compatibility with a polymer matrix. Assessment of the surface wettability of natural fibres using conventional methods presents a challenge as the surfaces are morphologically and chemically heterogeneous, rough, and can be strongly wicking. In this work it is shown that under atmospheric conditions the adhesion force between an atomic force microscopy (AFM) tip and the fibre surface can estimate the water contact angle and surface wettability of the fibre. AFM adhesion force measurements are suitable for the more difficult surfaces of natural fibres and in addition allow for correlations between microstructural features and surface wettability characteristics

Cellular Force Microscopy for in Vivo Measurements of Plant Tissue Mechanics1[W][OA

Science.gov (United States)

Routier-Kierzkowska, Anne-Lise; Weber, Alain; Kochova, Petra; Felekis, Dimitris; Nelson, Bradley J.; Kuhlemeier, Cris; Smith, Richard S.

2012-01-01

Although growth and morphogenesis are controlled by genetics, physical shape change in plant tissue results from a balance between cell wall loosening and intracellular pressure. Despite recent work demonstrating a role for mechanical signals in morphogenesis, precise measurement of mechanical properties at the individual cell level remains a technical challenge. To address this challenge, we have developed cellular force microscopy (CFM), which combines the versatility of classical microindentation techniques with the high automation and resolution approaching that of atomic force microscopy. CFM’s large range of forces provides the possibility to map the apparent stiffness of both plasmolyzed and turgid tissue as well as to perform micropuncture of cells using very high stresses. CFM experiments reveal that, within a tissue, local stiffness measurements can vary with the level of turgor pressure in an unexpected way. Altogether, our results highlight the importance of detailed physically based simulations for the interpretation of microindentation results. CFM’s ability to be used both to assess and manipulate tissue mechanics makes it a method of choice to unravel the feedbacks between mechanics, genetics, and morphogenesis. PMID:22353572

Nanoscale observation of local bound charges of patterned protein arrays by scanning force microscopy

International Nuclear Information System (INIS)

Oh, Y J; Jo, W; Kim, S; Park, S; Kim, Y S

2008-01-01

A protein patterned surface using micro-contact printing methods has been investigated by scanning force microscopy. Electrostatic force microscopy (EFM) was utilized for imaging the topography and detecting the electrical properties such as the local bound charge distribution of the patterned proteins. It was found that the patterned IgG proteins are arranged down to 1 μm, and the 90 deg. rotation of patterned anti-IgG proteins was successfully undertaken. Through the estimation of the effective areas, it was possible to determine the local bound charges of patterned proteins which have opposite electrostatic force behaviors. Moreover, we studied the binding probability between IgG and anti-IgG in a 1 μm 2 MIMIC system by topographic and electrostatic signals for applicable label-free detections. We showed that the patterned proteins can be used for immunoassay of proteins on the functional substrate, and that they can also be used for bioelectronics device application, indicating distinct advantages with regard to accuracy and a label-free detection

Theoretical study of the effect of probe shape on adhesion force between probe and substrate in atomic force microscope experiment

OpenAIRE

Yang, Li; Hu, Junhui; Kong, Lingjiang

2017-01-01

The quantitative description of adhesion force dependence on the probe shapes are of importance in many scientific and industrial fields. In order to elucidate how the adhesion force varied with the probe shape in atomic force microscope manipulation experiment, we performed a theoretical study of the influences of the probe shape (the sphere and parabolic probe) on the adhesion force at different humidity. We found that the combined action of the triple point and the Kelvin radius guiding th...

The Use of Contact Mode Atomic Force Microscopy in Aqueous Medium for Structural Analysis of Spinach Photosynthetic Complexes

Energy Technology Data Exchange (ETDEWEB)

Phuthong, Witchukorn; Huang, Zubin; Wittkopp, Tyler M.; Sznee, Kinga; Heinnickel, Mark L.; Dekker, Jan P.; Frese, Raoul N.; Prinz, Fritz B.; Grossman, Arthur R.

2015-07-28

To investigate the dynamics of photosynthetic pigment-protein complexes in vascular plants at high resolution in an aqueous environment, membrane-protruding oxygen-evolving complexes (OECs) associated with photosystem II (PSII) on spinach (Spinacia oleracea) grana membranes were examined using contact mode atomic force microscopy. This study represents, to our knowledge, the first use of atomic force microscopy to distinguish the putative large extrinsic loop of Photosystem II CP47 reaction center protein (CP47) from the putative oxygen-evolving enhancer proteins 1, 2, and 3 (PsbO, PsbP, and PsbQ) and large extrinsic loop of Photosystem II CP43 reaction center protein (CP43) in the PSII-OEC extrinsic domains of grana membranes under conditions resulting in the disordered arrangement of PSII-OEC particles. Moreover, we observed uncharacterized membrane particles that, based on their physical characteristics and electrophoretic analysis of the polypeptides associated with the grana samples, are hypothesized to be a domain of photosystem I that protrudes from the stromal face of single thylakoid bilayers. Our results are interpreted in the context of the results of others that were obtained using cryo-electron microscopy (and single particle analysis), negative staining and freeze-fracture electron microscopy, as well as previous atomic force microscopy studies.

Specific heats of lunar surface materials from 90 to 350 degrees Kelvin

Science.gov (United States)

Robie, R.A.; Hemingway, B.S.; Wilson, W.H.

1970-01-01

The specific heats of lunar samples 10057 and 10084 returned by the Apollo 11 mission have been measured between 90 and 350 degrees Kelvin by use of an adiabatic calorimeter. The samples are representative of type A vesicular basalt-like rocks and of finely divided lunar soil. The specific heat of these materials changes smoothly from about 0.06 calorie per gram per degree at 90 degrees Kelvin to about 0.2 calorie per gram per degree at 350 degrees Kelvin. The thermal parameter ??=(k??C)-1/2 for the lunar surface will accordingly vary by a factor of about 2 between lunar noon and midnight.

The effect of drive frequency and set point amplitude on tapping forces in atomic force microscopy: simulation and experiment

International Nuclear Information System (INIS)

Legleiter, Justin

2009-01-01

In tapping mode atomic force microscopy (AFM), a sharp probe tip attached to an oscillating cantilever is allowed to intermittently strike a surface. By raster scanning the probe while monitoring the oscillation amplitude of the cantilever via a feedback loop, topographical maps of surfaces with nanoscale resolution can be acquired. While numerous studies have employed numerical simulations to elucidate the time-resolved tapping force between the probe tip and surface, until recent technique developments, specific read-outs from such models could not be experimentally verified. In this study, we explore, via numerical simulation, the impact of imaging parameters, i.e. set point ratio and drive frequency as a function of resonance, on time-varying tip-sample force interactions, which are directly compared to reconstructed tapping forces from real AFM experiments. As the AFM model contains a feedback loop allowing for the simulation of the entire scanning process, we further explore the impact that various tip-sample force have on the entire imaging process.

Detection of stiff nanoparticles within cellular structures by contact resonance atomic force microscopy subsurface nanomechanical imaging.

Science.gov (United States)

Reggente, Melania; Passeri, Daniele; Angeloni, Livia; Scaramuzzo, Francesca Anna; Barteri, Mario; De Angelis, Francesca; Persiconi, Irene; De Stefano, Maria Egle; Rossi, Marco

2017-05-04

Detecting stiff nanoparticles buried in soft biological matrices by atomic force microscopy (AFM) based techniques represents a new frontier in the field of scanning probe microscopies, originally developed as surface characterization methods. Here we report the detection of stiff (magnetic) nanoparticles (NPs) internalized in cells by using contact resonance AFM (CR-AFM) employed as a potentially non-destructive subsurface characterization tool. Magnetite (Fe 3 O 4 ) NPs were internalized in microglial cells from cerebral cortices of mouse embryos of 18 days by phagocytosis. Nanomechanical imaging of cells was performed by detecting the contact resonance frequencies (CRFs) of an AFM cantilever held in contact with the sample. Agglomerates of NPs internalized in cells were visualized on the basis of the local increase in the contact stiffness with respect to the surrounding biological matrix. A second AFM-based technique for nanomechanical imaging, i.e., HarmoniX™, as well as magnetic force microscopy and light microscopy were used to confirm the CR-AFM results. Thus, CR-AFM was demonstrated as a promising technique for subsurface imaging of nanomaterials in biological samples.

Investigation of the structure of nanocrystalline refractory oxides by X-ray diffraction, electron microscopy, and atomic force microscopy

International Nuclear Information System (INIS)

Ulyanova, T. M.; Titova, L. V.; Medichenko, S. V.; Zonov, Yu. G.; Konstantinova, T. E.; Glazunova, V. A.; Doroshkevich, A. S.; Kuznetsova, T. A.

2006-01-01

The structures of nanocrystalline fibrous powders of refractory oxides have been investigated by different methods: determination of coherent-scattering regions, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic-force microscopy (AFM). The sizes of nanograins of different crystalline phases of refractory metal oxides have been determined during the formation of these nanograins and the dynamics of their growth during heat treatment in the temperature range 600-1600 deg. C has been studied. The data on the structure of nanocrystalline refractory oxide powders, obtained by different methods, are in good agreement. According to the data on coherent-scattering regions, the sizes of the ZrO 2 (Y 2 O 3 ) and Al 2 O 3 grains formed are in the range 4-6 nm, and the particle sizes determined according to the TEM and AFM data are in the ranges 5-7 and 2-10 nm, respectively. SEM analysis made it possible to investigate the dynamics of nanoparticle growth at temperatures above 1000 deg. C and establish the limiting temperatures of their consolidation in fibers

High resolution, large deformation 3D traction force microscopy.

Directory of Open Access Journals (Sweden)

Jennet Toyjanova

Full Text Available Traction Force Microscopy (TFM is a powerful approach for quantifying cell-material interactions that over the last two decades has contributed significantly to our understanding of cellular mechanosensing and mechanotransduction. In addition, recent advances in three-dimensional (3D imaging and traction force analysis (3D TFM have highlighted the significance of the third dimension in influencing various cellular processes. Yet irrespective of dimensionality, almost all TFM approaches have relied on a linear elastic theory framework to calculate cell surface tractions. Here we present a new high resolution 3D TFM algorithm which utilizes a large deformation formulation to quantify cellular displacement fields with unprecedented resolution. The results feature some of the first experimental evidence that cells are indeed capable of exerting large material deformations, which require the formulation of a new theoretical TFM framework to accurately calculate the traction forces. Based on our previous 3D TFM technique, we reformulate our approach to accurately account for large material deformation and quantitatively contrast and compare both linear and large deformation frameworks as a function of the applied cell deformation. Particular attention is paid in estimating the accuracy penalty associated with utilizing a traditional linear elastic approach in the presence of large deformation gradients.

In-situ piezoresponse force microscopy cantilever mode shape profiling

International Nuclear Information System (INIS)

Proksch, R.

2015-01-01

The frequency-dependent amplitude and phase in piezoresponse force microscopy (PFM) measurements are shown to be a consequence of the Euler-Bernoulli (EB) dynamics of atomic force microscope (AFM) cantilever beams used to make the measurements. Changes in the cantilever mode shape as a function of changes in the boundary conditions determine the sensitivity of cantilevers to forces between the tip and the sample. Conventional PFM and AFM measurements are made with the motion of the cantilever measured at one optical beam detector (OBD) spot location. A single OBD spot location provides a limited picture of the total cantilever motion, and in fact, experimentally observed cantilever amplitude and phase are shown to be strongly dependent on the OBD spot position for many measurements. In this work, the commonly observed frequency dependence of PFM response is explained through experimental measurements and analytic theoretical EB modeling of the PFM response as a function of both frequency and OBD spot location on a periodically poled lithium niobate sample. One notable conclusion is that a common choice of OBD spot location—at or near the tip of the cantilever—is particularly vulnerable to frequency dependent amplitude and phase variations stemming from dynamics of the cantilever sensor rather than from the piezoresponse of the sample

Active voltage contrast imaging of cross-sectional surface of multilayer ceramic capacitor using helium ion microscopy

Energy Technology Data Exchange (ETDEWEB)

Sakai, C., E-mail: SAKAI.Chikako@nims.go.jp; Ishida, N.; Masuda, H.; Nagano, S.; Kitahara, M.; Fujita, D. [National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Ogata, Y. [TAIYO YUDEN CO., LTD., Takasaki-shi, Gunma 370-3347 (Japan)

2016-08-01

We studied active voltage contrast (AVC) imaging using helium ion microscopy (HIM). We observed secondary electron (SE) images of the cross-sectional surface of multilayer ceramic capacitors (MLCCs) with and without a voltage applied to the internal electrodes. When no voltage was applied, we obtained an image reflecting the material contrast between the Ni internal electrode region and the BaTiO{sub 3} dielectric region of the cross-sectional surface of the MLCC. When a voltage was applied, the electrical potential difference between the grounded and the positively biased internal electrodes affected the contrast (voltage contrast). Moreover, attenuation of the SE intensity from the grounded to the positively biased internal electrodes was observed in the dielectric region. Kelvin probe force microscopy (KPFM) measurements of the contact potential difference (CPD) were performed on the same sample. By using the AVC image from the HIM observation and the CPD image from the KPFM measurement, we could quantitatively evaluate the electrical potential. We think that the results of this study will lead to an expansion in the number of applications of HIM.

Surface adhesion properties of graphene and graphene oxide studied by colloid-probe atomic force microscopy

International Nuclear Information System (INIS)

Ding Yanhuai; Zhang Ping; Ren Huming; Zhuo Qin; Yang Zhongmei; Jiang Xu; Jiang Yong

2011-01-01

Surface adhesion properties are important to various applications of graphene-based materials. Atomic force microscopy is powerful to study the adhesion properties of samples by measuring the forces on the colloidal sphere tip as it approaches and retracts from the surface. In this paper we have measured the adhesion force between the colloid probe and the surface of graphene (graphene oxide) nanosheet. The results revealed that the adhesion force on graphene and graphene oxide surface were 66.3 and 170.6 nN, respectively. It was found the adhesion force was mainly determined by the water meniscus, which was related to the surface contact angle of samples.

Characterization of nanoparticles using Atomic Force Microscopy

International Nuclear Information System (INIS)

Rao, A; Schoenenberger, M; Gnecco, E; Glatzel, Th; Meyer, E; Braendlin, D; Scandella, L

2007-01-01

Nanoparticles are becoming increasingly important in many areas, including catalysis, biomedical applications, and information storage. Their unique size-dependent properties make these materials superior. Using the Atomic Force Microscope (AFM), individual particles and groups of particles can be resolved and unlike other microscopy techniques, the AFM offers visualization and analysis in three dimensions. We prepared titanium oxide, zirconium oxide and alumina nanoparticles and/or agglomerates on different surfaces and characterized them by AFM in the dynamic mode. The goal was to determine the shape, size and/or size distribution of nanoparticles. Different dilutions of nanoparticles were applied on various substrates e.g. clean silicon, mica and chemically treated silicon and imaged at ambient conditions. Nanoparticles deposited on mica appeared to be coagulated as compared to those on silicon. Whereas, on a chemically treated surface the density of the nanoparticles was very low because of the increased hydrophobicity of the surface

STRUCTURE CONTROL FOR DIFFERENT TYPES OF PAPER BY ATOMIC FORCE MICROSCOPY

Directory of Open Access Journals (Sweden)

M. V. Zhukov

2014-01-01

Full Text Available The paper deals with the precision control for the parameters of manufactured paper production, such as various kinds of paper and photo paper for printing. Research of untreated, matte, glossy and laminated paper is conducted by atomic force microscopy by means of educational and scientific scanning probe microscope NanoEducator LE in the framework of this paper. Visualization of characteristic structure for each type of studied paper was conducted, histogram of roughness was obtained, and average roughness of height differences was defined. A laminated paper has got the lowest roughness (Ra of about 70 nm and glossy paper has got Ra of about 170 nm; roughness of untreated paper with cellulose fibers is about 530- 540 nm, and matte paper has got the highest roughness parameters (Ra about 670-680 nm. Scanning probe microscopy application for parameters monitoring of cellulosic paper production is shown to give the possibility of such microscopy type application in the production of paper products and high-precision control of its parameters.

Interfacing 3D magnetic twisting cytometry with confocal fluorescence microscopy to image force responses in living cells.

Science.gov (United States)

Zhang, Yuejin; Wei, Fuxiang; Poh, Yeh-Chuin; Jia, Qiong; Chen, Junjian; Chen, Junwei; Luo, Junyu; Yao, Wenting; Zhou, Wenwen; Huang, Wei; Yang, Fang; Zhang, Yao; Wang, Ning

2017-07-01

Cells and tissues can undergo a variety of biological and structural changes in response to mechanical forces. Only a few existing techniques are available for quantification of structural changes at high resolution in response to forces applied along different directions. 3D-magnetic twisting cytometry (3D-MTC) is a technique for applying local mechanical stresses to living cells. Here we describe a protocol for interfacing 3D-MTC with confocal fluorescence microscopy. In 3D-MTC, ferromagnetic beads are bound to the cell surface via surface receptors, followed by their magnetization in any desired direction. A magnetic twisting field in a different direction is then applied to generate rotational shear stresses in any desired direction. This protocol describes how to combine magnetic-field-induced mechanical stimulation with confocal fluorescence microscopy and provides an optional extension for super-resolution imaging using stimulated emission depletion (STED) nanoscopy. This technology allows for rapid real-time acquisition of a living cell's mechanical responses to forces via specific receptors and for quantifying structural and biochemical changes in the same cell using confocal fluorescence microscopy or STED. The integrated 3D-MTC-microscopy platform takes ∼20 d to construct, and the experimental procedures require ∼4 d when carried out by a life sciences graduate student.

¿Qué es una onda ecuatorial de Kelvin?

OpenAIRE

Ripa, P.

1980-01-01

La importancia del estudio de las ondas de Kelvin (ecuatoriales o costeras) radica, en parte, en el hecho de que éstas proveen un mecanismo eficaz para el transporte de energía (en la forma de perturbaciones de densidad y corriente) en una dirección particular. Estas señales se trasladan sin dispersión, es decir, sin cambiar de forma. Por otra parte, una onda de Kelvin provee un ejemplo muy sencillo de dos fenómenos fundamentales de la Oceanografía Física de frecuencias: el balance geostrófic...

Micropatterning of bacteria on two-dimensional lattice protein surface observed by atomic force microscopy

International Nuclear Information System (INIS)

Oh, Y.J.; Jo, W.; Lim, J.; Park, S.; Kim, Y.S.; Kim, Y.

2008-01-01

In this study, we characterized the two-dimensional lattice of bovine serum albumin (BSA) as a chemical and physical barrier against bacterial adhesion, using fluorescence microscopy and atomic force microscopy (AFM). The lattice of BSA on glass surface was fabricated by micro-contact printing (μCP), which is a useful way to pattern a wide range of molecules into microscale features on different types of substrates. The contact-mode AFM measurements showed that the average height of the printed BSA monolayer was 5-6 nm. Escherichia coli adhered rapidly on bare glass slide, while the bacterial adhesion was minimized on the lattices in the range of 1-3 μm 2 . Especially, the bacterial adhesion was completely inhibited on a 1 μm 2 lattice. The results suggest that the anti-adhesion effects are due by the steric repulsion forces exerted by BSA

Chiral Asymmetric Structures in Aspartic Acid and Valine Crystals Assessed by Atomic Force Microscopy.

Science.gov (United States)

Teschke, Omar; Soares, David Mendez

2016-03-29

Structures of crystallized deposits formed by the molecular self-assembly of aspartic acid and valine on silicon substrates were imaged by atomic force microscopy. Images of d- and l-aspartic acid crystal surfaces showing extended molecularly flat sheets or regions separated by single molecule thick steps are presented. Distinct orientation surfaces were imaged, which, combined with the single molecule step size, defines the geometry of the crystal. However, single molecule step growth also reveals the crystal chirality, i.e., growth orientations. The imaged ordered lattice of aspartic acid (asp) and valine (val) mostly revealed periodicities corresponding to bulk terminations, but a previously unreported molecular hexagonal lattice configuration was observed for both l-asp and l-val but not for d-asp or d-val. Atomic force microscopy can then be used to identify the different chiral forms of aspartic acid and valine crystals.

Imaging contrast and tip-sample interaction of non-contact amplitude modulation atomic force microscopy with Q -control

International Nuclear Information System (INIS)

Shi, Shuai; Guo, Dan; Luo, Jianbin

2017-01-01

Active quality factor ( Q ) exhibits many promising properties in dynamic atomic force microscopy. Energy dissipation and image contrasts are investigated in the non-contact amplitude modulation atomic force microscopy (AM-AFM) with an active Q -control circuit in the ambient air environment. Dissipated power and virial were calculated to compare the highly nonlinear interaction of tip-sample and image contrasts with different Q gain values. Greater free amplitudes and lower effective Q values show better contrasts for the same setpoint ratio. Active quality factor also can be employed to change tip-sample interaction force in non-contact regime. It is meaningful that non-destructive and better contrast images can be realized in non-contact AM-AFM by applying an active Q -control to the dynamic system. (paper)

Imaging surface nanobubbles at graphite–water interfaces with different atomic force microscopy modes

International Nuclear Information System (INIS)

Yang, Chih-Wen; Lu, Yi-Hsien; Hwang, Ing-Shouh

2013-01-01

We have imaged nanobubbles on highly ordered pyrolytic graphite (HOPG) surfaces in pure water with different atomic force microscopy (AFM) modes, including the frequency-modulation, the tapping, and the PeakForce techniques. We have compared the performance of these modes in obtaining the surface profiles of nanobubbles. The frequency-modulation mode yields a larger height value than the other two modes and can provide more accurate measurement of the surface profiles of nanobubbles. Imaging with PeakForce mode shows that a nanobubble appears smaller and shorter with increasing peak force and disappears above a certain peak force, but the size returns to the original value when the peak force is reduced. This indicates that imaging with high peak forces does not cause gas removal from the nanobubbles. Based on the presented findings and previous AFM observations, the existing models for nanobubbles are reviewed and discussed. The model of gas aggregate inside nanobubbles provides a better explanation for the puzzles of the high stability and the contact angle of surface nanobubbles. (paper)

Acid-base properties and the chemical imaging of surface-bound functional groups studied with scanning force microscopy

NARCIS (Netherlands)

van der Vegte, E.W.; Hadziioannou, G

1997-01-01

In this paper we present a scanning force microscopy (SFM) study on electrostatic and hydrogen-bonding interactions between chemically modified SFM probes and surface functional groups. pH-dependent adhesion force measurements in aqueous media between various ionizable functional groups showed a

Quantitative measurement of solvation shells using frequency modulated atomic force microscopy

Science.gov (United States)

Uchihashi, T.; Higgins, M.; Nakayama, Y.; Sader, J. E.; Jarvis, S. P.

2005-03-01

The nanoscale specificity of interaction measurements and additional imaging capability of the atomic force microscope make it an ideal technique for measuring solvation shells in a variety of liquids next to a range of materials. Unfortunately, the widespread use of atomic force microscopy for the measurement of solvation shells has been limited by uncertainties over the dimensions, composition and durability of the tip during the measurements, and problems associated with quantitative force calibration of the most sensitive dynamic measurement techniques. We address both these issues by the combined use of carbon nanotube high aspect ratio probes and quantifying the highly sensitive frequency modulation (FM) detection technique using a recently developed analytical method. Due to the excellent reproducibility of the measurement technique, additional information regarding solvation shell size as a function of proximity to the surface has been obtained for two very different liquids. Further, it has been possible to identify differences between chemical and geometrical effects in the chosen systems.

CO tip functionalization in subatomic resolution atomic force microscopy

International Nuclear Information System (INIS)

Kim, Minjung; Chelikowsky, James R.

2015-01-01

Noncontact atomic force microscopy (nc-AFM) employing a CO-functionalized tip displays dramatically enhanced resolution wherein covalent bonds of polycyclic aromatic hydrocarbon can be imaged. Employing real-space pseudopotential first-principles calculations, we examine the role of CO in functionalizing the nc-AFM tip. Our calculations allow us to simulate full AFM images and ascertain the enhancement mechanism of the CO molecule. We consider two approaches: one with an explicit inclusion of the CO molecule and one without. By comparing our simulations to existing experimental images, we ascribe the enhanced resolution of the CO functionalized tip to the special orbital characteristics of the CO molecule

Reverse engineering of an affinity-switchable molecular interaction characterized by atomic force microscopy single-molecule force spectroscopy.

Science.gov (United States)

Anselmetti, Dario; Bartels, Frank Wilco; Becker, Anke; Decker, Björn; Eckel, Rainer; McIntosh, Matthew; Mattay, Jochen; Plattner, Patrik; Ros, Robert; Schäfer, Christian; Sewald, Norbert

2008-02-19

Tunable and switchable interaction between molecules is a key for regulation and control of cellular processes. The translation of the underlying physicochemical principles to synthetic and switchable functional entities and molecules that can mimic the corresponding molecular functions is called reverse molecular engineering. We quantitatively investigated autoinducer-regulated DNA-protein interaction in bacterial gene regulation processes with single atomic force microscopy (AFM) molecule force spectroscopy in vitro, and developed an artificial bistable molecular host-guest system that can be controlled and regulated by external signals (UV light exposure and thermal energy). The intermolecular binding functionality (affinity) and its reproducible and reversible switching has been proven by AFM force spectroscopy at the single-molecule level. This affinity-tunable optomechanical switch will allow novel applications with respect to molecular manipulation, nanoscale rewritable molecular memories, and/or artificial ion channels, which will serve for the controlled transport and release of ions and neutral compounds in the future.

Electrostatic force microscopy on oriented graphite surfaces: coexistence of insulating and conducting behaviors.

Science.gov (United States)

Lu, Yonghua; Muñoz, M; Steplecaru, C S; Hao, Cheng; Bai, Ming; Garcia, N; Schindler, K; Esquinazi, P

2006-08-18

We present measurements of the electric potential fluctuations on the surface of highly oriented pyrolytic graphite using electrostatic force and atomic force microscopy. Micrometric domainlike potential distributions are observed even when the sample is grounded. Such potential distributions are unexpected given the good metallic conductivity of graphite because the surface should be an equipotential. Our results indicate the coexistence of regions with "metalliclike" and "insulatinglike" behaviors showing large potential fluctuations of the order of 0.25 V. In lower quality graphite, this effect is not observed. Experiments are performed in Ar and air atmospheres.

Binding activity of patterned concanavalin A studied by atomic force microscopy

International Nuclear Information System (INIS)

Lebed, Kateryna; Pyka-Fosciak, Grazyna; Raczkowska, Joanna; Lekka, Malgorzata; Styczen, Jan

2005-01-01

The mode of protein immobilization plays a crucial role in the preparation of protein microarrays used for a wide spectrum of applications in analytical biochemistry. The microcontact printing technique was used to form a protein pattern using concanavalin A (Con A) since Con A belongs to a group of proteins widely used in analytical assays due to their selectivity as regards different kinds of carbohydrates. Atomic force microscopy was used to image surface topography, delivering information about the quality of the protein pattern. The force spectroscopy mode was used to verify the functional activity of deposited proteins via determination of the forces of interaction between Con A and carboxypeptidase Y bearing carbohydrate structure recognized by Con A. The calculated binding force between Con A and CaY was 105 ± 2 pN and it was compared with that measured for Con A deposited directly from the protein solution. The similarity of the value obtained for the interaction force was independent of the mode of protein deposition, thereby verifying that the microcontact printing technique did not influence the carbohydrate binding activity of Con A. The correlation between the surface topography of patterned samples and adhesion maps obtained showed the possible use of AFM for studying the chemical properties of different regions of the micropatterns produced

DNA adsorption and desorption on mica surface studied by atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Sun Lanlan [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Graduate school of the Chinese Academy of Sciences, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022 (China); Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Zhao Dongxu [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Zhang Yue; Xu Fugang [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Graduate school of the Chinese Academy of Sciences, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022 (China); Li Zhuang, E-mail: zli@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Graduate school of the Chinese Academy of Sciences, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022 (China)

2011-05-15

The adsorption of DNA molecules on mica surface and the following desorption of DNA molecules at ethanol-mica interface were studied using atomic force microscopy. By changing DNA concentration, different morphologies on mica surface have been observed. A very uniform and orderly monolayer of DNA molecules was constructed on the mica surface with a DNA concentration of 30 ng/{mu}L. When the samples were immersed into ethanol for about 15 min, various desorption degree of DNA from mica (0-99%) was achieved. It was found that with the increase of DNA concentration, the desorption degree of DNA from the mica at ethanol-mica interface decreased. And when the uniform and orderly DNA monolayers were formed on the mica surface, almost no DNA molecule desorbed from the mica surface in this process. The results indicated that the uniform and orderly DNA monolayer is one of the most stable DNA structures formed on the mica surface. In addition, we have studied the structure change of DNA molecules after desorbed from the mica surface with atomic force microscopy, and found that the desorption might be ascribed to the ethanol-induced DNA condensation.

DNA adsorption and desorption on mica surface studied by atomic force microscopy

International Nuclear Information System (INIS)

Sun Lanlan; Zhao Dongxu; Zhang Yue; Xu Fugang; Li Zhuang

2011-01-01

The adsorption of DNA molecules on mica surface and the following desorption of DNA molecules at ethanol-mica interface were studied using atomic force microscopy. By changing DNA concentration, different morphologies on mica surface have been observed. A very uniform and orderly monolayer of DNA molecules was constructed on the mica surface with a DNA concentration of 30 ng/μL. When the samples were immersed into ethanol for about 15 min, various desorption degree of DNA from mica (0-99%) was achieved. It was found that with the increase of DNA concentration, the desorption degree of DNA from the mica at ethanol-mica interface decreased. And when the uniform and orderly DNA monolayers were formed on the mica surface, almost no DNA molecule desorbed from the mica surface in this process. The results indicated that the uniform and orderly DNA monolayer is one of the most stable DNA structures formed on the mica surface. In addition, we have studied the structure change of DNA molecules after desorbed from the mica surface with atomic force microscopy, and found that the desorption might be ascribed to the ethanol-induced DNA condensation.

Enhanced efficiency in the excitation of higher modes for atomic force microscopy and mechanical sensors operated in liquids

Energy Technology Data Exchange (ETDEWEB)

Penedo, M., E-mail: mapenedo@imm.cnm.csic.es; Hormeño, S.; Fernández-Martínez, I.; Luna, M.; Briones, F. [IMM-Instituto de Microelectrónica de Madrid (CNM-CSIC), Isaac Newton 8, PTM, E-28760 Tres Cantos, Madrid (Spain); Raman, A. [Birck Nanotechnology Center and School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47904 (United States)

2014-10-27

Recent developments in dynamic Atomic Force Microscopy where several eigenmodes are simultaneously excited in liquid media are proving to be an excellent tool in biological studies. Despite its relevance, the search for a reliable, efficient, and strong cantilever excitation method is still in progress. Herein, we present a theoretical modeling and experimental results of different actuation methods compatible with the operation of Atomic Force Microscopy in liquid environments: ideal acoustic, homogeneously distributed force, distributed applied torque (MAC Mode™), photothermal and magnetostrictive excitation. From the analysis of the results, it can be concluded that magnetostriction is the strongest and most efficient technique for higher eigenmode excitation when using soft cantilevers in liquid media.

Parametric Amplification Protocol for Frequency-Modulated Magnetic Resonance Force Microscopy Signals

Science.gov (United States)

Harrell, Lee; Moore, Eric; Lee, Sanggap; Hickman, Steven; Marohn, John

2011-03-01

We present data and theoretical signal and noise calculations for a protocol using parametric amplification to evade the inherent tradeoff between signal and detector frequency noise in force-gradient magnetic resonance force microscopy signals, which are manifested as a modulated frequency shift of a high- Q microcantilever. Substrate-induced frequency noise has a 1 / f frequency dependence, while detector noise exhibits an f2 dependence on modulation frequency f . Modulation of sample spins at a frequency that minimizes these two contributions typically results in a surface frequency noise power an order of magnitude or more above the thermal limit and may prove incompatible with sample spin relaxation times as well. We show that the frequency modulated force-gradient signal can be used to excite the fundamental resonant mode of the cantilever, resulting in an audio frequency amplitude signal that is readily detected with a low-noise fiber optic interferometer. This technique allows us to modulate the force-gradient signal at a sufficiently high frequency so that substrate-induced frequency noise is evaded without subjecting the signal to the normal f2 detector noise of conventional demodulation.

Surprising volume change in PPy(DBS): An atomic force microscopy study

DEFF Research Database (Denmark)

Smela, E.; Gadegaard, N.

1999-01-01

Communication: Conjugated polymers such as polypyrrole (PPy) have potential use as artificial muscles or in microsystems such as valves for micro-fluid handling. One of the most important parameters in such uses is the magnitude of volume change during associated redox processes; however, until now...... estimates have varied greatly. Atomic force microscopy is reported here as allowing direct measurement of the in situ thickness change during oxidation and reduction of thin films of PPy doped with dodecylbenzenesulfonate....

Investigating bioconjugation by atomic force microscopy

Science.gov (United States)

2013-01-01

Nanotechnological applications increasingly exploit the selectivity and processivity of biological molecules. Integration of biomolecules such as proteins or DNA into nano-systems typically requires their conjugation to surfaces, for example of carbon-nanotubes or fluorescent quantum dots. The bioconjugated nanostructures exploit the unique strengths of both their biological and nanoparticle components and are used in diverse, future oriented research areas ranging from nanoelectronics to biosensing and nanomedicine. Atomic force microscopy imaging provides valuable, direct insight for the evaluation of different conjugation approaches at the level of the individual molecules. Recent technical advances have enabled high speed imaging by AFM supporting time resolutions sufficient to follow conformational changes of intricately assembled nanostructures in solution. In addition, integration of AFM with different spectroscopic and imaging approaches provides an enhanced level of information on the investigated sample. Furthermore, the AFM itself can serve as an active tool for the assembly of nanostructures based on bioconjugation. AFM is hence a major workhorse in nanotechnology; it is a powerful tool for the structural investigation of bioconjugation and bioconjugation-induced effects as well as the simultaneous active assembly and analysis of bioconjugation-based nanostructures. PMID:23855448

Conductive atomic force microscopy studies on the transformation of GeSi quantum dots to quantum rings.

Science.gov (United States)

Zhang, S L; Xue, F; Wu, R; Cui, J; Jiang, Z M; Yang, X J

2009-04-01

Conductive atomic force microscopy has been employed to study the topography and conductance distribution of individual GeSi quantum dots (QDs) and quantum rings (QRs) during the transformation from QDs to QRs by depositing an Si capping layer on QDs. The current distribution changes significantly with the topographic transformation during the Si capping process. Without the capping layer, the QDs are dome-shaped and the conductance is higher at the ring region between the center and boundary than that at the center. After capping with 0.32 nm Si, the shape of the QDs changes to pyramidal and the current is higher at both the center and the arris. When the Si capping layer increases to 2 nm, QRs are formed and the current of individual QRs is higher at the rim than that at the central hole. By comparing the composition distributions obtained by scanning Auger microscopy and atomic force microscopy combined with selective chemical etching, the origin of the current distribution change is discussed.

Multi-MHz micro-electro-mechanical sensors for atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Legrand, Bernard, E-mail: bernard.legrand@laas.fr [LAAS-CNRS, Université de Toulouse, CNRS, 7 avenue du colonel Roche, F-31400 Toulouse (France); Salvetat, Jean-Paul [CRPP, 115 avenue Schweitzer, F-33600 Pessac (France); Walter, Benjamin; Faucher, Marc; Théron, Didier [IEMN, avenue Henri Poincaré, F-59652 Villeneuve d’Ascq (France); Aimé, Jean-Pierre [CBMN, allée Geoffroy Saint Hilaire, Bât. B14, F-33600 Pessac (France)

2017-04-15

Silicon ring-shaped micro-electro-mechanical resonators have been fabricated and used as probes for dynamic atomic force microscopy (AFM) experiments. They offer resotnance frequency above 10 MHz, which is notably greater than that of usual cantilevers and quartz-based AFM probes. On-chip electrical actuation and readout of the tip oscillation are obtained by means of built-in capacitive transducers. Displacement and force resolutions have been determined from noise analysis at 1.5 fm/√Hz and 0.4 pN/√Hz, respectively. Despite the high effective stiffness of the probes, the tip-surface interaction force is kept below 1 nN by using vibration amplitude significantly below 100 pm and setpoint close to the free vibration conditions. Imaging capabilities in amplitude- and frequency-modulation AFM modes have been demonstrated on block copolymer surfaces. Z-spectroscopy experiments revealed that the tip is vibrating in permanent contact with the viscoelastic material, with a pinned contact line. Results are compared to those obtained with commercial AFM cantilevers driven at large amplitudes (>10 nm). - Highlights: • Silicon MEMS resonators are used as AFM probes above 10 MHz. • Integrated capacitive transducers drive and sense sub-nanometer tip oscillation. • Force resolution is below 1 pN/√Hz. • Block copolymer surface is imaged using AM and FM AFM modes. • Probes are operated at small vibration amplitude in permanent viscoelastic contact.

Multi-MHz micro-electro-mechanical sensors for atomic force microscopy

International Nuclear Information System (INIS)

Legrand, Bernard; Salvetat, Jean-Paul; Walter, Benjamin; Faucher, Marc; Théron, Didier; Aimé, Jean-Pierre

2017-01-01

Silicon ring-shaped micro-electro-mechanical resonators have been fabricated and used as probes for dynamic atomic force microscopy (AFM) experiments. They offer resotnance frequency above 10 MHz, which is notably greater than that of usual cantilevers and quartz-based AFM probes. On-chip electrical actuation and readout of the tip oscillation are obtained by means of built-in capacitive transducers. Displacement and force resolutions have been determined from noise analysis at 1.5 fm/√Hz and 0.4 pN/√Hz, respectively. Despite the high effective stiffness of the probes, the tip-surface interaction force is kept below 1 nN by using vibration amplitude significantly below 100 pm and setpoint close to the free vibration conditions. Imaging capabilities in amplitude- and frequency-modulation AFM modes have been demonstrated on block copolymer surfaces. Z-spectroscopy experiments revealed that the tip is vibrating in permanent contact with the viscoelastic material, with a pinned contact line. Results are compared to those obtained with commercial AFM cantilevers driven at large amplitudes (>10 nm). - Highlights: • Silicon MEMS resonators are used as AFM probes above 10 MHz. • Integrated capacitive transducers drive and sense sub-nanometer tip oscillation. • Force resolution is below 1 pN/√Hz. • Block copolymer surface is imaged using AM and FM AFM modes. • Probes are operated at small vibration amplitude in permanent viscoelastic contact.

Current mapping of low-energy (120 eV) helium and hydrogen irradiated tungsten by conductive atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Fan, Hongyu [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China); Endo, Takashi [Nano-micro Materials Analysis Laboratory, Hokkaido University, Sapporo (Japan); Bi, Zhenghua; Yan, Weibin [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China); Ohnuki, Somei [Nano-micro Materials Analysis Laboratory, Hokkaido University, Sapporo (Japan); Yang, Qi; Ni, Weiyuan [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China); Liu, Dongping, E-mail: dongping.liu@dlnu.edu.cn [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China)

2017-04-01

Both conductive atomic force microscopy (CAFM) and transmission electron microscopy have been used to characterize the defects or He bubbles in low-energy (120 eV) H and He irradiated tungsten (W). By a comparative study, we find that the current mapping from CAFM is very sensitive in the detection of nanometer-sized defects in low-energy H and He irradiated W. Our calculation confirms that the resistance change in H and He irradiated W is strongly affected by the distance between atomic force microscopy tip and defects/He bubbles. CAFM can accurately detect defects/He bubbles in the W surface layer, however, it is infeasible to measure them in the deep layer (>20 nm), especially due to the existence of defects in the surface layer.

Automatic kelvin probe compatible with ultrahigh vacuum

NARCIS (Netherlands)

Baikie, I.D.; van der Werf, Kees; Oerbekke, H.; Broeze, J.; van Silfhout, Arend

1989-01-01

This article describes a new type of in situ ultrahigh‐vacuum compatible kelvin probe based on a voice‐coil driving mechanism. This design exhibits several advantages over conventional mechanical feed‐through and (in situ) piezoelectric devices in regard to the possibility of multiple probe

Identification of 6H-SiC polar faces with pull-off force of atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Gan, Di; Song, Youting; Yang, Junwei; Chen, Hongxiang [Research & development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Guo, Liwei, E-mail: lwguo@iphy.ac.cn [Research & development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Xiaolong, E-mail: chenx29@iphy.ac.cn [Research & development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

2016-12-30

Highlights: • A new method is proposed and demonstrated to distinguish the polar faces of 6H-SiC by pull-off forces which are clearly different on the Si-face and the C-face of 6H-SiC. • The reliability of this method is confirmed on 6H-SiC samples treated with different surface processing procedures. • The essence of different pull-off forces on different polar faces of 6H-SiC is that the surface energies between them are obviously different. • Theoretical calculations are consistent with our experimental results. - Abstract: Distinguishing SiC (0001) Si-face from SiC (000-1) C-face without any damages is extremely important because the two polar faces have different physical and chemical properties which seriously influence the quality of a homoepitaxy or heteroepitaxy thin film on it. Here, a convenient and nondestructive detection method is developed to distinguish the Si-face and C-face of a (0001) oriented SiC wafer by employing a pull-off force measurement using atomic force microscopy. It is found that the pull-off force from a Si-face of 6H-SiC is about two times of that from a C-face, no matter it is a two-face chemical mechanical polishing or etched 6H-SiC wafer. The method developed here is suitable to identify polar faces of materials only if the two polar faces having different surface energy.

Nanoscale investigation on Pseudomonas aeruginosa biofilm formed on porous silicon using atomic force microscopy.

Science.gov (United States)

Kannan, Ashwin; Karumanchi, Subbalakshmi Latha; Krishna, Vinatha; Thiruvengadam, Kothai; Ramalingam, Subramaniam; Gautam, Pennathur

2014-01-01

Colonization of surfaces by bacterial cells results in the formation of biofilms. There is a need to study the factors that are important for formation of biofilms since biofilms have been implicated in the failure of semiconductor devices and implants. In the present study, the adhesion force of biofilms (formed by Pseudomonas aeruginosa) on porous silicon substrates of varying surface roughness was quantified using atomic force microscopy (AFM). The experiments were carried out to quantify the effect of surface roughness on the adhesion force of biofilm. The results show that the adhesion force increased from 1.5 ± 0.5 to 13.2 ± 0.9 nN with increase in the surface roughness of silicon substrate. The results suggest that the adhesion force of biofilm is affected by surface roughness of substrate. © 2014 Wiley Periodicals, Inc.

Atomic force microscopy and mechanical testing of bovine pericardium irradiated to radiotherapy doses

International Nuclear Information System (INIS)

Daar, Eman; Kaabar, W.; Woods, E.; Lei, C.; Nisbet, A.; Bradley, D.A.

2014-01-01

Within the context of radiotherapy our work investigates the feasibility of identifying changes in structural and biomechanical properties of pericardium resulting from exposure to penetrating photon irradiation. Collagen fibres extracted from bovine pericardium were chosen as a model of pericardium extracellular matrix as these form the main fibrous component of the medium. Tests of mechanical properties, controlled by the various structural elements of the tissues, were performed on frontal pericardium, including uni-axial tests and atomic force microscopy (AFM). While the irradiated collagen fibres showed no significant change in D-band spacing up to doses of 80 Gy, the fibre width was found to increase by 34±9% at 80 Gy when compared with that for un-irradiated samples. - Highlights: • Methods for identifying changes in tissue biophysical properties following photon irradiation. • Tests made using collagen fibres extracted from bovine pericardium. • Sensitivity of uni-axial tests and atomic force microscopy (AFM) investigated. • Radiotherapy doses investigated up to 80 Gy, delivered by 6 MV photons

Visualising the Micro World of Chemical/Geochemical Interactions Using Atomic Force Microscopy (AFM)

Energy Technology Data Exchange (ETDEWEB)

Graham, G M; Sorbie, K S

1997-12-31

Scanning force microscopy, in particular AFM (Atomic Force Microscopy), provides a particular useful and interesting tool for the examination of surface structure at the near-atomic level. AFM is particularly well suited to the study of interactions at the surface in aqueous solutions using real time in-situ measurements. In this paper there is presented AFM images showing in situ crystal growth from supersaturated BaSO{sub 4} solutions onto the surface of barite. Growth structures in the form of spiral crystal growth features, presumably originating from screw dislocations, are illustrated. AFM images of novel scale crystal growth inhibition experiments are presented. Examination of the manner in which generically different species adsorb onto growth structures may help to explain mechanistic differences in the way which different inhibitor species perform against barium sulphate scale formation. Adsorption of polyacrylamide species onto mica surfaces have been viewed. The general utility of AFM to a number of other common surface interactions in oil field chemistry will be discussed. 17 refs., 3 figs.

Characterization of virus-like particles by atomic force microscopy in ambient conditions

International Nuclear Information System (INIS)

Oropesa, Reinier; Ramos, Jorge R; Falcón, Viviana; Felipe, Ariel

2013-01-01

Recombinant virus-like particles (VLPs) are attractive candidates for vaccine design since they resemble native viroids in size and morphology, but they are non-infectious due to the absence of a viral genome. The visualization of surface morphologies and structures can be used to deepen the understanding of physical, chemical, and biological phenomena. Atomic force microscopy (AFM) is a useful tool for the visualization of soft biological samples in a nanoscale resolution. In this work we have investigated the morphology of recombinant surface antigens of hepatitis B (rHBsAg) VLPs from Cuban vaccine against hepatitis B. The rHBsAg VLPs sizes estimated by AFM between 15 and 30 nm are similar to those reported on previous transmission electron microscopy (TEM) studies. (paper)

Molecular recognition of DNA-protein complexes: A straightforward method combining scanning force and fluorescence microscopy

NARCIS (Netherlands)

H. Sanchez (Humberto); R. Kanaar (Roland); C. Wyman (Claire)

2010-01-01

textabstractCombining scanning force and fluorescent microscopy allows simultaneous identification of labeled biomolecules and analysis of their nanometer level architectural arrangement. Fluorescent polystyrene nano-spheres were used as reliable objects for alignment of optical and topographic

Modeling and simulation of viscoelastic biological particles' 3D manipulation using atomic force microscopy

Science.gov (United States)

Korayem, M. H.; Habibi Sooha, Y.; Rastegar, Z.

2018-05-01

Manipulation of the biological particles by atomic force microscopy is used to transfer these particles inside body's cells, diagnosis and destruction of the cancer cells and drug delivery to damaged cells. According to the impossibility of simultaneous observation of this process, the importance of modeling and simulation can be realized. The contact of the tip with biological particle is important during manipulation, therefore, the first step of the modeling is choosing appropriate contact model. Most of the studies about contact between atomic force microscopy and biological particles, consider the biological particle as an elastic material. This is not an appropriate assumption because biological cells are basically soft and this assumption ignores loading history. In this paper, elastic and viscoelastic JKR theories were used in modeling and simulation of the 3D manipulation for three modes of tip-particle sliding, particle-substrate sliding and particle-substrate rolling. Results showed that critical force and time in motion modes (sliding and rolling) for two elastic and viscoelastic states are very close but these magnitudes were lower in the viscoelastic state. Then, three friction models, Coulomb, LuGre and HK, were used for tip-particle sliding mode in the first phase of manipulation to make results closer to reality. In both Coulomb and LuGre models, critical force and time are very close for elastic and viscoelastic states but in general critical force and time prediction of HK model was higher than LuGre and the LuGre model itself had higher prediction than Coulomb.

The effect of adhesion on the contact radius in atomic force microscopy indentation

International Nuclear Information System (INIS)

Sirghi, L; Rossi, F

2009-01-01

The effect of adhesion on nanoscale indentation experiments makes the interpretation of force-displacement curves acquired in these experiments very difficult. The indentation force results from the addition of adhesive and elastic forces at the indenter-sample contact. The evolution of the two forces during the indentation is determined by the variation of the indenter-sample contact radius. In the present work the variation of contact radius during atomic force microscopy (AFM) indentation of elastic and adhesive samples with conical indenters (AFM tips) is indirectly determined by measurements of the contact dynamic stiffness. For weak sample deformations, the contact radius is determined mainly by the adhesion force and indenter apex radius. For strong sample deformations, the contact radius increases linearly with the increase of the indenter displacement, the slope of this linear dependence being in agreement with Sneddon's theory of indentation (Sneddon 1965 Int. J. Eng. Sci. 3 47). Based on these results, a theoretical expression of indentation force dependence on displacement is found. This expression allows for determination of the thermodynamic work of adhesion at the indenter-sample interface and the sample elasticity modulus.

Probing the stiffness of isolated nucleoli by atomic force microscopy.

Science.gov (United States)

Louvet, Emilie; Yoshida, Aiko; Kumeta, Masahiro; Takeyasu, Kunio

2014-04-01

In eukaryotic cells, ribosome biogenesis occurs in the nucleolus, a membraneless nuclear compartment. Noticeably, the nucleolus is also involved in several nuclear functions, such as cell cycle regulation, non-ribosomal ribonucleoprotein complex assembly, aggresome formation and some virus assembly. The most intriguing question about the nucleolus is how such dynamics processes can occur in such a compact compartment. We hypothesized that its structure may be rather flexible. To investigate this, we used atomic force microscopy (AFM) on isolated nucleoli. Surface topography imaging revealed the beaded structure of the nucleolar surface. With the AFM's ability to measure forces, we were able to determine the stiffness of isolated nucleoli. We could establish that the nucleolar stiffness varies upon drastic morphological changes induced by transcription and proteasome inhibition. Furthermore, upon ribosomal proteins and LaminB1 knockdowns, the nucleolar stiffness was increased. This led us to propose a model where the nucleolus has steady-state stiffness dependent on ribosome biogenesis activity and requires LaminB1 for its flexibility.

Atomic force microscopy on chromosomes, chromatin and DNA: a review.

Science.gov (United States)

Kalle, Wouter; Strappe, Padraig

2012-12-01

The purpose of this review is to discuss the achievements and progress that has been made in the use of atomic force microscopy in DNA related research in the last 25 years. For this review DNA related research is split up in chromosomal-, chromatin- and DNA focused research to achieve a logical flow from large- to smaller structures. The focus of this review is not only on the AFM as imaging tool but also on the AFM as measuring tool using force spectroscopy, as therein lays its greatest advantage and future. The amazing technological and experimental progress that has been made during the last 25 years is too extensive to fully cover in this review but some key developments and experiments have been described to give an overview of the evolution of AFM use from 'imaging tool' to 'measurement tool' on chromosomes, chromatin and DNA. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Piezo-generated charge mapping revealed through direct piezoelectric force microscopy.

Science.gov (United States)

Gomez, A; Gich, M; Carretero-Genevrier, A; Puig, T; Obradors, X

2017-10-24

While piezoelectric and ferroelectric materials play a key role in many everyday applications, there are still a number of open questions related to their physics. To enhance our understanding of piezoelectrics and ferroelectrics, nanoscale characterization is essential. Here, we develop an atomic force microscopy based mode that obtains a direct quantitative analysis of the piezoelectric coefficient d 33 . We report nanoscale images of piezogenerated charge in a thick single crystal of periodically poled lithium niobate (PPLN), a bismuth ferrite (BiFO 3 ) thin film, and lead zirconate titanate (PZT) by applying a force and recording the current produced by these materials. The quantification of d 33 coefficients for PPLN (14 ± 3 pC per N) and BFO (43 ± 6 pC per N) is in agreement with the values reported in the literature. Even stronger evidence of the reliability of the method is provided by an equally accurate measurement of the significantly larger d 33 of PZT.

Structure and stability of semiconductor tip apexes for atomic force microscopy

International Nuclear Information System (INIS)

Pou, P; Perez, R; Ghasemi, S A; Goedecker, S; Jelinek, P; Lenosky, T

2009-01-01

The short range force between the tip and the surface atoms, that is responsible for atomic-scale contrast in atomic force microscopy (AFM), is mainly controlled by the tip apex. Thus, the ability to image, manipulate and chemically identify single atoms in semiconductor surfaces is ultimately determined by the apex structure and its composition. Here we present a detailed and systematic study of the most common structures that can be expected at the apex of the Si tips used in experiments. We tackle the determination of the structure and stability of Si tips with three different approaches: (i) first principles simulations of small tip apexes; (ii) simulated annealing of a Si cluster; and (iii) a minima hopping study of large Si tips. We have probed the tip apexes by making atomic contacts between the tips and then compared force-distance curves with the experimental short range forces obtained with dynamic force spectroscopy. The main conclusion is that although there are multiple stable solutions for the atomically sharp tip apexes, they can be grouped into a few types with characteristic atomic structures and properties. We also show that the structure of the last atomic layers in a tip apex can be both crystalline and amorphous. We corroborate that the atomically sharp tips are thermodynamically stable and that the tip-surface interaction helps to produce the atomic protrusion needed to get atomic resolution.

Nanoindentation of Pseudomonas aeruginosa bacterial biofilm using atomic force microscopy

International Nuclear Information System (INIS)

Baniasadi, Mahmoud; Xu, Zhe; Du, Yingjie; Lu, Hongbing; Minary-Jolandan, Majid; Gandee, Leah; Zimmern, Philippe

2014-01-01

Bacterial biofilms are a source of many chronic infections. Biofilms and their inherent resistance to antibiotics are attributable to a range of health issues including affecting prosthetic implants, hospital-acquired infections, and wound infection. Mechanical properties of biofilm, in particular, at micro- and nano-scales, are governed by microstructures and porosity of the biofilm, which in turn may contribute to their inherent antibiotic resistance. We utilize atomic force microscopy (AFM)-based nanoindentation and finite element simulation to investigate the nanoscale mechanical properties of Pseudomonas aeruginosa bacterial biofilm. This biofilm was derived from human samples and represents a medically relevant model. (paper)

Characterization of the magnetic micro- and nanostructure in unalloyed steels by magnetic force microscopy

Science.gov (United States)

Batista, L.; Rabe, U.; Hirsekorn, S.

2013-01-01

The formation of a cementite phase influences significantly the macroscopic mechanical and magnetic properties of steels. Based on a correlation between mechanical and magnetic properties, mechanical properties as well as the morphology and content of the cementite phase can be inspected by electromagnetic non-destructive testing methods. The influence of the carbon content on bulk magnetic properties of unalloyed steels is studied on a macroscopic scale by hysteresis loop and Barkhausen noise measurements. The micro- and nanostructure is investigated by atomic force microscopy and magnetic force microscopy. Surface topography images and magnetic images of globular cementite precipitates embedded in a ferrite matrix are presented. The size, shape, and orientation of the precipitates influence the domain configuration. Applied external magnetic fields cause magnetization processes mainly in the ferrite matrix: Bloch walls move and are pinned by the cementite precipitates. The correlation between the microscopic observations and macroscopic magnetic properties of the material is discussed.

Quantitative measurement of local elasticity of SiOx film by atomic force acoustic microscopy

International Nuclear Information System (INIS)

Cun-Fu, He; Gai-Mei, Zhang; Bin, Wu

2010-01-01

In this paper the elastic properties of SiO x film are investigated quantitatively for local fixed point and qualitatively for overall area by atomic force acoustic microscopy (AFAM) in which the sample is vibrated at the ultrasonic frequency while the sample surface is touched and scanned with the tip contacting the sample respectively for fixed point and continuous measurements. The SiO x films on the silicon wafers are prepared by the plasma enhanced chemical vapour deposition (PECVD). The local contact stiffness of the tip-SiO x film is calculated from the contact resonance spectrum measured with the atomic force acoustic microscopy. Using the reference approach, indentation modulus of SiO x film for fixed point is obtained. The images of cantilever amplitude are also visualized and analysed when the SiO x surface is excited at a fixed frequency. The results show that the acoustic amplitude images can reflect the elastic properties of the sample. (classical areas of phenomenology)

The development of the spatially correlated adjustment wavelet filter for atomic force microscopy data.

Science.gov (United States)

Sikora, Andrzej; Rodak, Aleksander; Unold, Olgierd; Klapetek, Petr

2016-12-01

In this paper a novel approach for the practical utilization of the 2D wavelet filter in terms of the artifacts removal from atomic force microscopy measurements results is presented. The utilization of additional data such as summary photodiode signal map is implemented in terms of the identification of the areas requiring the data processing, filtering settings optimization and the verification of the process performance. Such an approach allows to perform the filtering parameters adjustment by average user, while the straightforward method requires an expertise in this field. The procedure was developed as the function of the Gwyddion software. The examples of filtering the phase imaging and Electrostatic Force Microscopy measurement result are presented. As the wavelet filtering feature may remove a local artifacts, its superior efficiency over similar approach with 2D Fast Fourier Transformate based filter (2D FFT) can be noticed. Copyright © 2016 Elsevier B.V. All rights reserved.

Identification by force modulation microscopy of nanoparticles generated in vacuum arcs Identification by force modulation microscopy of nanoparticles generated in vacuum arcs

Directory of Open Access Journals (Sweden)

M. Arroyave Franco

2006-06-01

Full Text Available An alternative method based on force modulation microscopy (FMM for identification of nanoparticles produced in the plasma generated by the cathode spots of vacuum arcs is presented. FMM technique is enabled for the detection of variations in the mechanical properties of a surface with high sensitiveness. Titanium nitride (TiN coatings deposited on oriented silicon by pulsed vacuum arc process have been analyzed. AFM (Atomic Force Microscopy and FMM images were simultaneously obtained, and in all cases it was possible to identify nanoparticle presence. Further X-ray Diffraction spectra of sample coating were taken. Existence of contaminant particles of 47 nanometers in diameter was reported.En este trabajo se presenta un método alternativo basado en microscopia de modulación de fuerza (FMM, para la identificación de nanogotas producidas en el plasma generado por los spots catódicos de los arcos en vacío. La técnica FMM esta habilitada para la detección de variaciones en las propiedades mecánicas de una superficie, con alta sensibilidad. Se han analizado recubrimientos de nitruro de titanio (TiN depositados sobre Silicio orientado por el proceso de arco en vacío pulsado. Se han obtenido simultáneamente imágenes de microscopia de fuerza atómica (AFM y de microscopia FMM mediante las cuales se ha podido identificar la presencia de nanogotas. Adicionalmente se han tomado espectros de difracción de rayos X (XRD de las muestras recubiertas. Se ha reportado la existencia de partículas contaminantes de 47 nanómetros de diámetro sobre los recubrimientos.

Enhanced quality factors and force sensitivity by attaching magnetic beads to cantilevers for atomic force microscopy in liquid

Science.gov (United States)

Hoof, Sebastian; Nand Gosvami, Nitya; Hoogenboom, Bart W.

2012-12-01

Dynamic-mode atomic force microscopy (AFM) in liquid remains complicated due to the strong viscous damping of the cantilever resonance. Here, we show that a high-quality resonance (Q >20) can be achieved in aqueous solution by attaching a microgram-bead at the end of the nanogram-cantilever. The resulting increase in cantilever mass causes the resonance frequency to drop significantly. However, the force sensitivity—as expressed via the minimum detectable force gradient—is hardly affected, because of the enhanced quality factor. Through the enhancement of the quality factor, the attached bead also reduces the relative importance of noise in the deflection detector. It can thus yield an improved signal-to-noise ratio when this detector noise is significant. We describe and analyze these effects for a set-up that includes magnetic actuation of the cantilevers and that can be easily implemented in any AFM system that is compatible with an inverted optical microscope.

Piezoelectric properties of PbTiO(3) thin films characterized with piezoresponse force and high resolution transmission electron microscopy

NARCIS (Netherlands)

Morelli, A.; Venkatesan, Sriram; Kooi, B. J.; Palasantzas, G.; De Hosson, J. Th. M.

2009-01-01

In this paper we investigate the piezoelectric properties of PbTiO(3) thin films grown by pulsed laser deposition with piezoresponse force microscopy and transmission electron microscopy. The as-grown films exhibit an upward polarization, inhomogeneous distribution of piezoelectric characteristics

Investigation of Kelvin wave periods during Hai-Tang typhoon using Empirical Mode Decomposition

Science.gov (United States)

Kishore, P.; Jayalakshmi, J.; Lin, Pay-Liam; Velicogna, Isabella; Sutterley, Tyler C.; Ciracì, Enrico; Mohajerani, Yara; Kumar, S. Balaji

2017-11-01

Equatorial Kelvin waves (KWs) are fundamental components of the tropical climate system. In this study, we investigate Kelvin waves (KWs) during the Hai-Tang typhoon of 2005 using Empirical Mode Decomposition (EMD) of regional precipitation, zonal and meridional winds. For the analysis, we use daily precipitation datasets from the Global Precipitation Climatology Project (GPCP) and wind datasets from the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-analysis (ERA-Interim). As an additional measurement, we use in-situ precipitation datasets from rain-gauges over the Taiwan region. The maximum accumulated precipitation was approximately 2400 mm during the period July 17-21, 2005 over the southwestern region of Taiwan. The spectral analysis using the wind speed at 950 hPa found in the 2nd, 3rd, and 4th intrinsic mode functions (IMFs) reveals prevailing Kelvin wave periods of ∼3 days, ∼4-6 days, and ∼6-10 days, respectively. From our analysis of precipitation datasets, we found the Kelvin waves oscillated with periods between ∼8 and 20 days.

A resolution study for electrostatic force microscopy on bimetallic samples using the boundary element method

International Nuclear Information System (INIS)

Shen Yongxing; Lee, Minhwan; Lee, Wonyoung; Barnett, David M; Pinsky, Peter M; Prinz, Friedrich B

2008-01-01

Electrostatic force microscopy (EFM) is a special design of non-contact atomic force microscopy used for detecting electrostatic interactions between the probe tip and the sample. Its resolution is limited by the finite probe size and the long-range characteristics of electrostatic forces. Therefore, quantitative analysis is crucial to understanding the relationship between the actual local surface potential distribution and the quantities obtained from EFM measurements. To study EFM measurements on bimetallic samples with surface potential inhomogeneities as a special case, we have simulated such measurements using the boundary element method and calculated the force component and force gradient component that would be measured by amplitude modulation (AM) EFM and frequency modulation (FM) EFM, respectively. Such analyses have been performed for inhomogeneities of various shapes and sizes, for different tip-sample separations and tip geometries, for different applied voltages, and for different media (e.g., vacuum or water) in which the experiment is performed. For a sample with a surface potential discontinuity, the FM-EFM resolution expression agrees with the literature; however, the simulation for AM-EFM suggests the existence of an optimal tip radius of curvature in terms of resolution. On the other hand, for samples with strip- and disk-shaped surface potential inhomogeneities, we have obtained quantitative expressions for the detectability size requirements as a function of experimental conditions for both AM- and FM-EFMs, which suggest that a larger tip radius of curvature is moderately favored for detecting the presence of such inhomogeneities

Specialized probes based on hydroxyapatite calcium for heart tissues research by atomic force microscopy

International Nuclear Information System (INIS)

Zhukov, Mikhail; Golubok, Alexander; Gulyaev, Nikolai

2016-01-01

The new specialized AFM-probes with hydroxyapatite structures for atomic force microscopy of heart tissues calcification were created and studied. A process of probe fabrication is demonstrated. The adhesive forces between specialized hydroxyapatite probe and endothelium/subendothelial layers were investigated. It was found that the adhesion forces are significantly higher for the subendothelial layers. We consider that it is connected with the formation and localization of hydroxyapatite in the area of subendothelial layers of heart tissues. In addition, the roughness analysis and structure visualization of the endothelial surface of the heart tissue were carried out. The results show high efficiency of created specialized probes at study a calcinations process of the aortic heart tissues.

Single molecule imaging of RNA polymerase II using atomic force microscopy

International Nuclear Information System (INIS)

Rhodin, Thor; Fu Jianhua; Umemura, Kazuo; Gad, Mohammed; Jarvis, Suzi; Ishikawa, Mitsuru

2003-01-01

An atomic force microscopy (AFM) study of the shape, orientation and surface topology of RNA polymerase II supported on silanized freshly cleaved mica was made. The overall aim is to define the molecular topology of RNA polymerase II in appropriate fluids to help clarify the relationship of conformational features to biofunctionality. A Nanoscope III atomic force microscope was used in the tapping mode with oxide-sharpened (8-10 nm) Si 3 N 4 probes in aqueous zinc chloride buffer. The main structural features observed by AFM were compared to those derived from electron-density plots based on X-ray crystallographic studies. The conformational features included a bilobal silhouette with an inverted umbrella-shaped crater connected to a reaction site. These studies provide a starting point for constructing a 3D-AFM profiling analysis of proteins such as RNA polymerase complexes

Subharmonic Oscillations and Chaos in Dynamic Atomic Force Microscopy

Science.gov (United States)

Cantrell, John H.; Cantrell, Sean A.

2015-01-01

The increasing use of dynamic atomic force microscopy (d-AFM) for nanoscale materials characterization calls for a deeper understanding of the cantilever dynamics influencing scan stability, predictability, and image quality. Model development is critical to such understanding. Renormalization of the equations governing d- AFM provides a simple interpretation of cantilever dynamics as a single spring and mass system with frequency dependent cantilever stiffness and damping parameters. The renormalized model is sufficiently robust to predict the experimentally observed splitting of the free-space cantilever resonance into multiple resonances upon cantilever-sample contact. Central to the model is the representation of the cantilever sample interaction force as a polynomial expansion with coefficients F(sub ij) (i,j = 0, 1, 2) that account for the effective interaction stiffness parameter, the cantilever-to-sample energy transfer, and the amplitude of cantilever oscillation. Application of the Melnikov method to the model equation is shown to predict a homoclinic bifurcation of the Smale horseshoe type leading to a cascade of period doublings with increasing drive displacement amplitude culminating in chaos and loss of image quality. The threshold value of the drive displacement amplitude necessary to initiate subharmonic generation depends on the acoustic drive frequency, the effective damping coefficient, and the nonlinearity of the cantilever-sample interaction force. For parameter values leading to displacement amplitudes below threshold for homoclinic bifurcation other bifurcation scenarios can occur, some of which lead to chaos.

Solid-state nuclear-spin quantum computer based on magnetic resonance force microscopy

International Nuclear Information System (INIS)

Berman, G. P.; Doolen, G. D.; Hammel, P. C.; Tsifrinovich, V. I.

2000-01-01

We propose a nuclear-spin quantum computer based on magnetic resonance force microscopy (MRFM). It is shown that an MRFM single-electron spin measurement provides three essential requirements for quantum computation in solids: (a) preparation of the ground state, (b) one- and two-qubit quantum logic gates, and (c) a measurement of the final state. The proposed quantum computer can operate at temperatures up to 1 K. (c) 2000 The American Physical Society

Nanoscale liquid interfaces wetting, patterning and force microscopy at the molecular scale

CERN Document Server

Ondarçuhu, Thierry

2013-01-01

This book addresses the recent developments in the investigation and manipulation of liquids at the nanoscale. This new field has shown important breakthroughs on the basic understanding of physical mechanisms involving liquid interfaces, which led to applications in nanopatterning. It has also consequences in force microscopy imaging in liquid environment. The book proposes is a timely review of these various aspects. It is co-authored by 25 among the most prominent scientists in the field.

Going Vertical To Improve the Accuracy of Atomic Force Microscopy Based Single-Molecule Force Spectroscopy.

Science.gov (United States)

Walder, Robert; Van Patten, William J; Adhikari, Ayush; Perkins, Thomas T

2018-01-23

Single-molecule force spectroscopy (SMFS) is a powerful technique to characterize the energy landscape of individual proteins, the mechanical properties of nucleic acids, and the strength of receptor-ligand interactions. Atomic force microscopy (AFM)-based SMFS benefits from ongoing progress in improving the precision and stability of cantilevers and the AFM itself. Underappreciated is that the accuracy of such AFM studies remains hindered by inadvertently stretching molecules at an angle while measuring only the vertical component of the force and extension, degrading both measurements. This inaccuracy is particularly problematic in AFM studies using double-stranded DNA and RNA due to their large persistence length (p ≈ 50 nm), often limiting such studies to other SMFS platforms (e.g., custom-built optical and magnetic tweezers). Here, we developed an automated algorithm that aligns the AFM tip above the DNA's attachment point to a coverslip. Importantly, this algorithm was performed at low force (10-20 pN) and relatively fast (15-25 s), preserving the connection between the tip and the target molecule. Our data revealed large uncorrected lateral offsets for 100 and 650 nm DNA molecules [24 ± 18 nm (mean ± standard deviation) and 180 ± 110 nm, respectively]. Correcting this offset yielded a 3-fold improvement in accuracy and precision when characterizing DNA's overstretching transition. We also demonstrated high throughput by acquiring 88 geometrically corrected force-extension curves of a single individual 100 nm DNA molecule in ∼40 min and versatility by aligning polyprotein- and PEG-based protein-ligand assays. Importantly, our software-based algorithm was implemented on a commercial AFM, so it can be broadly adopted. More generally, this work illustrates how to enhance AFM-based SMFS by developing more sophisticated data-acquisition protocols.

Atomic force microscopy analysis of synthetic membranes applied in release studies

Energy Technology Data Exchange (ETDEWEB)

Olejnik, Anna, E-mail: annamar@amu.edu.pl; Nowak, Izabela

2015-11-15

Graphical abstract: - Highlights: • We compare eight synthetic membranes by atomic force microscopy. • We predict the behavior of membranes in the release experiments. • The polymeric synthetic membranes varied in shape and size. • We detect substructures in pores of cellulose esters and nylon membranes. • Substructures limit the release rate of active compound. - Abstract: Synthetic membranes are commonly used in drug release studies and are applied mostly in quality control. They contain pores through which the drug can be diffused directly into the receptor fluid. Investigation of synthetic membranes permits determination of their structure and characterization of their properties. We suggest that the preliminary characterization of the membranes can be relevant to the interpretation of the release results. The aim of this study was to compare eight synthetic membranes by using atomic force microscopy in order to predict and understand their behavior in the release experiments. The results proved that polytetrafluoroethylene membrane was not suitable for the release study of tetrapeptide due to its hydrophobic nature, thickness and the specific structure with high trapezoid shaped blocks. The additional substructures in pores of mixed cellulose esters and nylon membranes detected by AFM influenced the diffusion rate of the active compound. These findings indicate that the selection of the membrane for the release studies should be performed cautiously by taking into consideration the membrane properties and by analyzing them prior the experiment.

Atomic force microscopy analysis of synthetic membranes applied in release studies

International Nuclear Information System (INIS)

Olejnik, Anna; Nowak, Izabela

2015-01-01

Graphical abstract: - Highlights: • We compare eight synthetic membranes by atomic force microscopy. • We predict the behavior of membranes in the release experiments. • The polymeric synthetic membranes varied in shape and size. • We detect substructures in pores of cellulose esters and nylon membranes. • Substructures limit the release rate of active compound. - Abstract: Synthetic membranes are commonly used in drug release studies and are applied mostly in quality control. They contain pores through which the drug can be diffused directly into the receptor fluid. Investigation of synthetic membranes permits determination of their structure and characterization of their properties. We suggest that the preliminary characterization of the membranes can be relevant to the interpretation of the release results. The aim of this study was to compare eight synthetic membranes by using atomic force microscopy in order to predict and understand their behavior in the release experiments. The results proved that polytetrafluoroethylene membrane was not suitable for the release study of tetrapeptide due to its hydrophobic nature, thickness and the specific structure with high trapezoid shaped blocks. The additional substructures in pores of mixed cellulose esters and nylon membranes detected by AFM influenced the diffusion rate of the active compound. These findings indicate that the selection of the membrane for the release studies should be performed cautiously by taking into consideration the membrane properties and by analyzing them prior the experiment.

Observations of crystallization and melting in poly(ethylene oxide)/poly(methyl methacrylate) blends by hot-stage atomic-force microscopy

NARCIS (Netherlands)

Pearce, R.; Vancso, Gyula J.

1998-01-01

The binary blend of poly(ethylene oxide)/atactic poly(methyl methacrylate) is examined using hot-stage atomic-force microscopy (AFM) in conjunction with differential scanning calorimetry and optical microscopy. It was found possible to follow in real time the melting process, which reveals itself to

Conductive scanning probe microscopy of the semicontinuous gold film and its SERS enhancement toward two-step photo-induced charge transfer and effect of the supportive layer

Science.gov (United States)

Sinthiptharakoon, K.; Sapcharoenkun, C.; Nuntawong, N.; Duong, B.; Wutikhun, T.; Treetong, A.; Meemuk, B.; Kasamechonchung, P.; Klamchuen, A.

2018-05-01

The semicontinuous gold film, enabling various electronic applications including development of surface-enhanced Raman scattering (SERS) substrate, is investigated using conductive atomic force microscopy (CAFM) and Kelvin probe force microscopy (KPFM) to reveal and investigate local electronic characteristics potentially associated with SERS generation of the film material. Although the gold film fully covers the underlying silicon surface, CAFM results reveal that local conductivity of the film is not continuous with insulating nanoislands appearing throughout the surface due to incomplete film percolation. Our analysis also suggests the two-step photo-induced charge transfer (CT) play the dominant role in the enhancement of SERS intensity with strong contribution from free electrons of the silicon support. Silicon-to-gold charge transport is illustrated by KPFM results showing that Fermi level of the gold film is slightly inhomogeneous and far below the silicon conduction band. We propose that inhomogeneity of the film workfunction affecting chemical charge transfer between gold and Raman probe molecule is associated with the SERS intensity varying across the surface. These findings provide deeper understanding of charge transfer mechanism for SERS which can help in design and development of the semicontinuous gold film-based SERS substrate and other electronic applications.

Modeling and boundary force control of microcantilevers utilized in atomic force microscopy for cellular imaging and characterization

Science.gov (United States)

Eslami, Sohrab

This dissertation undertakes the theoretical and experimental developments microcantilevers utilized in Atomic Force Microscopy (AFM) with applications to cellular imaging and characterization. The capability of revealing the inhomogeneties or interior of ultra-small materials has been of most interest to many researchers. However, the fundamental concept of signal and image formation remains unexplored and not fully understood. For his, a semi-empirical nonlinear force model is proposed to show that virtual frequency generation, regarded as the simplest synthesized subsurface probe, occurs optimally when the force is tuned to the van der Waals form. This is the first-time observation of a novel theoretical dynamic multi-frequency force microscopy that has not been already reported. Owing to the broad applications of microcantilevers in the nanoscale imaging and microscopic techniques, there is an essential feeling to study and propose a comprehensive model of such systems. Therefore, in the theoretical part of this dissertation, a distributed-parameters representation modeling of the microcantilever along with a general interaction force comprising of two attractive and repulsive components with general amplitude and power terms is studied. This model is investigated in a general 2D Cartesian coordinate to consider the motions of the probe with a tip mass. There is an excitation at the microcantilever's base such that the end of the beam is subject to the proposed general force. These forces are very sensitive to the amplitude and power terms of these parts; on the other hand, atomic intermolecular force is a function of the distance such that this distance itself is also a function of the interaction force that will result in a nonlinear implicit equation. From a parametric study in the probe-sample excitation, it is shown that the predicted behavior of the generated difference-frequency oscillation amplitude agrees well with experimental measurements. Following

Characterization of polyethersulfone-polyimide hollow fiber membranes by atomic force microscopy and contact angle goniometery

NARCIS (Netherlands)

Khulbe, K.C.; Feng, C.; Matsuura, T.; Kapantaidakis, G.; Wessling, Matthias; Koops, G.H.

2003-01-01

Asymmetric blend polyethersulfone-polyimide (PES-PI) hollow fiber membranes prepared at different air gap and used for gas separation are characterized by atomic force microscopy (inside and out side surfaces) and by measuring the contact angle of out side surface. The outer surface was entirely

Magnetic resonance force microscopy of paramagnetic electron spins at millikelvin temperatures.

Science.gov (United States)

Vinante, A; Wijts, G; Usenko, O; Schinkelshoek, L; Oosterkamp, T H

2011-12-06

Magnetic resonance force microscopy (MRFM) is a powerful technique to detect a small number of spins that relies on force detection by an ultrasoft magnetically tipped cantilever and selective magnetic resonance manipulation of the spins. MRFM would greatly benefit from ultralow temperature operation, because of lower thermomechanical noise and increased thermal spin polarization. Here we demonstrate MRFM operation at temperatures as low as 30 mK, thanks to a recently developed superconducting quantum interference device (SQUID)-based cantilever detection technique, which avoids cantilever overheating. In our experiment, we detect dangling bond paramagnetic centres on a silicon surface down to millikelvin temperatures. Fluctuations of such defects are supposedly linked to 1/f magnetic noise and decoherence in SQUIDs, as well as in several superconducting and single spin qubits. We find evidence that spin diffusion has a key role in the low-temperature spin dynamics.

Theoretical atomic-force-microscopy study of a stepped surface: Nonlocal effects in the probe

International Nuclear Information System (INIS)

Girard, C.

1991-01-01

The interaction force between a metallic tip and a nonplanar dielectric surface is derived from a nonlocal formalism. A general formulation is given for the case of a spherical tip of nanometer size and for surfaces of arbitrary shapes (stepped surfaces and single crystals adsorbed on a planar surface). The dispersion part of the attractive force is obtained from a nonlocal theory expressed in terms of generalized electric susceptibilities of the two constituents. Implications for atomic force microscopy in attractive modes are discussed. In this context, the present model indicates two different forms of corrugation: those due to the protuberance present on the tip leading to atomic corrugations; nanometer-sized corrugations detected in the attractive region by the spherical part of the tip

Charging effects and surface potential variations of Cu-based nanowires

Energy Technology Data Exchange (ETDEWEB)

Nunes, D., E-mail: daniela.gomes@fct.unl.pt [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica (Portugal); Calmeiro, T.R.; Nandy, S.; Pinto, J.V.; Pimentel, A.; Barquinha, P. [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica (Portugal); Carvalho, P.A. [SINTEF Materials and Chemistry, PB 124 Blindern, NO-0314, Oslo (Norway); CeFEMA, Instituto Superior Técnico, Universidade de Lisboa, 1049-001, Lisboa (Portugal); Walmsley, J.C. [SINTEF Materials and Chemistry, Materials and Nanotechnology, Høgskoleringen 5, 7034 Trondheim (Norway); Fortunato, E., E-mail: emf@fct.unl.pt [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica (Portugal); Martins, R., E-mail: rm@uninova.pt [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica (Portugal)

2016-02-29

The present work reports charging effects and surface potential variations in pure copper, cuprous oxide and cupric oxide nanowires observed by electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). The copper nanowires were produced by wet synthesis, oxidation into cuprous oxide nanowires was achieved through microwave irradiation and cupric oxide nanowires were obtained via furnace annealing in atmospheric conditions. Structural characterization of the nanowires was carried out by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. During the EFM experiments the electrostatic field of the positive probe charged negatively the Cu-based nanowires, which in turn polarized the SiO{sub 2} dielectric substrate. Both the probe/nanowire capacitance as well as the substrate polarization increased with the applied bias. Cu{sub 2}O and CuO nanowires behaved distinctively during the EFM measurements in accordance with their band gap energies. The work functions (WF) of the Cu-based nanowires, obtained by KPFM measurements, yielded WF{sub CuO} > WF{sub Cu} > WF{sub Cu{sub 2O}}. - Highlights: • Charge distribution study in Cu, Cu{sub 2}O and CuO nanowires through electrostatic force microscopy • Structural/surface defect role on the charge distribution along the Cu nanowires • Determination of the nanowire work functions by Kelvin probe force microscopy • Three types of nanowires give a broad idea of charge behavior on Cu based-nanowires.

Comparison between magnetic force microscopy and electron back-scatter diffraction for ferrite quantification in type 321 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Warren, A.D., E-mail: Xander.Warren@bristol.ac.uk [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); Harniman, R.L. [School of Chemistry, University of Bristol, Bristol BS8 1 TS (United Kingdom); Collins, A.M. [School of Chemistry, University of Bristol, Bristol BS8 1 TS (United Kingdom); Bristol Centre for Functional Nanomaterials, Nanoscience and Quantum Information Centre, University of Bristol, Bristol BS8 1FD (United Kingdom); Davis, S.A. [School of Chemistry, University of Bristol, Bristol BS8 1 TS (United Kingdom); Younes, C.M. [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); Flewitt, P.E.J. [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); School of Physics, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); Scott, T.B. [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom)

2015-01-15

Several analytical techniques that are currently available can be used to determine the spatial distribution and amount of austenite, ferrite and precipitate phases in steels. The application of magnetic force microscopy, in particular, to study the local microstructure of stainless steels is beneficial due to the selectivity of this technique for detection of ferromagnetic phases. In the comparison of Magnetic Force Microscopy and Electron Back-Scatter Diffraction for the morphological mapping and quantification of ferrite, the degree of sub-surface measurement has been found to be critical. Through the use of surface shielding, it has been possible to show that Magnetic Force Microscopy has a measurement depth of 105–140 nm. A comparison of the two techniques together with the depth of measurement capabilities are discussed. - Highlights: • MFM used to map distribution and quantify ferrite in type 321 stainless steels. • MFM results compared with EBSD for same region, showing good spatial correlation. • MFM gives higher area fraction of ferrite than EBSD due to sub-surface measurement. • From controlled experiments MFM depth sensitivity measured from 105 to 140 nm. • A correction factor to calculate area fraction from MFM data is estimated.

Decay characteristics of electronic charged states of Si quantum dots as evaluated by an AFM/Kelvin probe technique

International Nuclear Information System (INIS)

Nishitani, Junichiro; Makihara, Katsunori; Ikeda, Mitsuhisa; Murakami, Hideki; Higashi, Seiichiro; Miyazaki, Seiichi

2006-01-01

Si quantum dots (Si-QDs) with an areal dot density of 8 x 10 11 cm -2 on SiO 2 have been prepared by the thermal decomposition of monosilane to characterize charged states of Si-QDs using AFM/Kelvin probe force microscopy (KFM). The temporal changes in the surface potential induced by electron charging and discharging at Si-QDs covered with a ∼ 2-nm-thick oxide layer have been measured. In electron charging and discharging at Si-QDs, a Rh-coated AFM tip was electrically biased in the range of - 5 to 5 V and scanned on the sample surface in a tapping mode. The surface potential changes on Si-QDs by electron injection and extraction were observable, while no potential change was detected elsewhere. The surface potential of charged Si-QDs decays with time at rates depending on charge injection conditions. The observed decay characteristics can be interpreted in terms of discharging of stored electrons in Si-QDs due to electron tunneling through the bottom oxide to the substrate and neutralization of stored holes due to recombination with electrons tunneling from the substrates. The defect generation in oxide is likely to be responsible for a fairly slow decay as observed in the case of electron extraction by the tip bias as high as + 4.8 V with respect to p-Si(100)

Progress towards a new definition of the kelvin

Science.gov (United States)

Fischer, Joachim

2015-10-01

At its 24th meeting (2011) the General Conference on Weights and Measures noted the CIPM’s intention to express new definitions of the kilogram, ampere, kelvin, and mole in terms of fixed numerical values of the Planck constant, elementary charge, Boltzmann constant, and Avogadro constant, respectively. The changes proposed for the International System of Units will not actually be adopted until the experimental results on the new definitional constants that are proposed have reached a further stage of refinement. This paper provides an overview of the activities and progress of the research groups who are carrying out experiments to determine the Boltzmann constant. The most promising methods, acoustic gas thermometry, dielectric-constant gas thermometry, Johnson noise thermometry and Doppler-broadening thermometry, are reviewed. The prospects for meeting the requirements of the Consultative Committee for Thermometry for a new definition of the kelvin are discussed.

Nanometer-Scale Dissection of Chromosomes by Atomic Force Microscopy Combined with Heat-Denaturing Treatment

Science.gov (United States)

Tsukamoto, Kazumi; Kuwazaki, Seigo; Yamamoto, Kimiko; Shichiri, Motoharu; Yoshino, Tomoyuki; Ohtani, Toshio; Sugiyama, Shigeru

2006-03-01

We have developed a method for dissecting chromosome fragments with a size of a few hundred nanometers by atomic force microscopy (AFM). By using this method, we demonstrated reproducible dissections of silkworm chromosomes in the pachytene phase. The dissected fragments were successfully recovered on the cantilever tips, as confirmed by fluorescent microscopy using fluorescent stained chromosomes. To recover dissected chromosome fragments from a larger chromosome, such as the human metaphase chromosome of a somatic cell, heat denaturation was found to be effective. Further improvements in this method may lead to a novel tool for isolating valuable genes and/or investigating local genome structures in the near future.

Diameter measurements of polystyrene particles with atomic force microscopy

International Nuclear Information System (INIS)

Garnaes, J

2011-01-01

The size of (nano) particles is a key parameter used in controlling their function. The particle size is also important in order to understand their physical and chemical properties and regulate their number in health and safety issues. In this work, the geometric diameters of polystyrene spheres of nominal diameter 100 nm are measured using atomic force microscopy. The measurements are based on the apex height and on the average distance between neighbouring spheres when they form a close-packed monolayer on a flat mica substrate. The most important influence parameters for the determination of the geometric diameter are the lateral air gaps and deformation of the spheres. The lateral air gaps are caused by significant size variations of the individual spheres, and a correction is calculated based on the simulation of packing of spheres. The deformation of the spheres is caused mainly by capillary forces acting when they are in contact with each other or with the mica substrate. Based on calculated capillary forces and the literature values of the elastic properties of the polystyrene and mica, the deformation is estimated to be 2 nm with a standard uncertainty of 2 nm. The geometric diameter of the polystyrene spheres was measured with a combined standard uncertainty of ≈3 nm. The measured vertical diameter of 92.3 nm and the certified mobility equivalent diameter measured by differential mobility analysis (DMA) are marginally consistent at a confidence level of 95%. However, the measured lateral geometric diameter was 98.9 nm and is in good agreement with DMA

Characterization of local hydrophobicity on sapphire (0001) surfaces in aqueous environment by colloidal probe atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Wada, Tomoya; Yamazaki, Kenji; Isono, Toshinari; Ogino, Toshio, E-mail: ogino-toshio-rx@ynu.ac.jp

2017-02-28

Highlights: • Local hydrophobicity of phase-separated sapphire (0001) surfaces was investigated. • These surfaces are featured by coexistence of hydrophilic and hydrophobic domains. • Each domain was characterized by colloidal probe atomic force microscopy in water. • Both domains can be distinguished by adhesive forces of the probe to the surfaces. • Characterization in aqueous environment is important in bio-applications of sapphire. - Abstract: Sapphire (0001) surfaces exhibit a phase-separation into hydrophobic and hydrophilic domains upon high-temperature annealing, which were previously distinguished by the thickness of adsorbed water layers in air using atomic force microscopy (AFM). To characterize their local surface hydrophobicity in aqueous environment, we used AFM equipped with a colloidal probe and measured the local adhesive force between each sapphire domain and a hydrophilic SiO{sub 2} probe surface, or a hydrophobic polystyrene one. Two data acquisition modes for statistical analyses were used: one is force measurements at different positions of the surface and the other repeated measurement at a fixed position. We found that adhesive force measurements using the polystyrene probe allow us to distinctly separate the hydrophilic and hydrophobic domains. The dispersion in the force measurement data at different positions of the surface is larger than that in the repeated measurements at a fixed position. It indicates that the adhesive force measurement is repeatable although their data dispersion for the measurement positions is relatively large. From these results, we can conclude that the hydrophilic and hydrophobic domains on the sapphire (0001) surfaces are distinguished by a difference in their hydration degrees.

Two-dimensional dopant profiling by electrostatic force microscopy using carbon nanotube modified cantilevers

International Nuclear Information System (INIS)

Chin, S.-C.; Chang, Y.-C.; Chang, C.-S.; Tsong, T T; Hsu, Chen-Chih; Wu, Chih-I; Lin, W-H; Woon, W-Y; Lin, L-T; Tao, H-J

2008-01-01

A two-dimensional (2D) dopant profiling technique is demonstrated in this work. We apply a unique cantilever probe in electrostatic force microscopy (EFM) modified by the attachment of a multiwalled carbon nanotube (MWNT). Furthermore, the tip apex of the MWNT was trimmed to the sharpness of a single-walled carbon nanotube (SWNT). This ultra-sharp MWNT tip helps us to resolve dopant features to within 10 nm in air, which approaches the resolution achieved by ultra-high vacuum scanning tunnelling microscopy (UHV STM). In this study, the CNT-probed EFM is used to profile 2D buried dopant distribution under a nano-scale device structure and shows the feasibility of device characterization for sub-45 nm complementary metal-oxide-semiconductor (CMOS) field-effect transistors

Artifact-free dynamic atomic force microscopy reveals monotonic dissipation for a simple confined liquid

Science.gov (United States)

Kaggwa, G. B.; Kilpatrick, J. I.; Sader, J. E.; Jarvis, S. P.

2008-07-01

We present definitive interaction measurements of a simple confined liquid (octamethylcyclotetrasiloxane) using artifact-free frequency modulation atomic force microscopy. We use existing theory to decouple the conservative and dissipative components of the interaction, for a known phase offset from resonance (90° phase shift), that has been deliberately introduced into the experiment. Further we show the qualitative influence on the conservative and dissipative components of the interaction of a phase error deliberately introduced into the measurement, highlighting that artifacts, such as oscillatory dissipation, can be readily observed when the phase error is not compensated for in the force analysis.

Quantification of the lift height for magnetic force microscopy using 3D surface parameters

International Nuclear Information System (INIS)

Nenadovic, M.; Strbac, S.; Rakocevic, Z.

2010-01-01

In this work, the quantitative conditions for the lift height for imaging of the magnetic field using magnetic force microscopy (MFM) were optimized. A thin cobalt film deposited on a monocrystalline silicon (1 0 0) substrate with a thickness of 55 nm and a thin nickel film deposited on a glass with a thickness of 600 nm were used as samples. The topography of the surface was acquired by tapping mode atomic force microscopy (AFM), while MFM imaging was performed in the lift mode for various lift heights. It was determined that the sensitivity of the measurements was about 10% higher for images obtained at a scan angle of 90 o compared to a scan angle of 0 deg. Therefore, the three-dimensional surface texture parameters, i.e., average roughness, skewness, kurtosis and the bearing ratio, were determined in dependence on the lift height for a scan angle of 90 deg. The results of the analyses of the surface parameters showed that the influence of the substrate and its texture on the magnetic force image could be neglected for lift heights above 40 nm and that the upper lift height limit is 100 nm. It was determined that the optimal values of the lift heights were in the range from 60 to 80 nm, depending on the nature of the sample and on the type of the tip used.

Effect of plasma density profile of tokamak on Kelvin-Helmholtz instability

International Nuclear Information System (INIS)

Tang Fulin

1984-01-01

The purpose of this paper is to study the effect of radial distribution of plasma density profile of tokamak on Kelvin-Helmholtz instability caused by toroidal rotation. The effect of radial distribution of plasma rotational velocity on stability is also examine for comparison. It is found that within the range of tokamak parameters the only radial distribution of plasma rotational velocity cannot induce Kelvin-Helmholtz instability. On the contrary, when there is a radial distribution of plasma density, i.e. P 01 =P 0 e -tx and V 0 1 = const, plasma becomes unstable, and instability will increase proportionally to the value of t. Meanwhile when the value of t remains constant, the instability growth rate will decrease if P 0 grows or the distance between plasma and wall of container decreases too. It shows that the Kelvin-Helmoltz instability is not only influenced by the steepness of density profile but also by the inertia of plasma in central region, which is helpful for depressing the instability. (author). 5 refs, 4 figs, 2 tabs

Atomic Force Microscopy Application in Biological Research: A Review Study

Directory of Open Access Journals (Sweden)

Surena Vahabi

2013-06-01

Full Text Available Atomic force microscopy (AFM is a three-dimensional topographic technique with a high atomic resolution to measure surface roughness. AFM is a kind of scanning probe microscope, and its near-field technique is based on the interaction between a sharp tip and the atoms of the sample surface. There are several methods and many ways to modify the tip of the AFM to investigate surface properties, including measuring friction, adhesion forces and viscoelastic properties as well as determining the Young modulus and imaging magnetic or electrostatic properties. The AFM technique can analyze any kind of samples such as polymers, adsorbed molecules, films or fibers, and powders in the air whether in a controlled atmosphere or in a liquid medium. In the past decade, the AFM has emerged as a powerful tool to obtain the nanostructural details and biomechanical properties of biological samples, including biomolecules and cells. The AFM applications, techniques, and -in particular- its ability to measure forces, are not still familiar to most clinicians. This paper reviews the literature on the main principles of the AFM modality and highlights the advantages of this technique in biology, medicine, and- especially- dentistry. This literature review was performed through E-resources, including Science Direct, PubMed, Blackwell Synergy, Embase, Elsevier, and Scholar Google for the references published between 1985 and 2010.

Evaluation of preparation methods for suspended nano-objects on substrates for dimensional measurements by atomic force microscopy

OpenAIRE

Fiala, Petra; G?hler, Daniel; Wessely, Benno; Stintz, Michael; Lazzerini, Giovanni Mattia; Yacoot, Andrew

2017-01-01

Dimensional measurements on nano-objects by atomic force microscopy (AFM) require samples of safely fixed and well individualized particles with a suitable surface-specific particle number on flat and clean substrates. Several known and proven particle preparation methods, i.e., membrane filtration, drying, rinsing, dip coating as well as electrostatic and thermal precipitation, were performed by means of scanning electron microscopy to examine their suitability for preparing samples for dime...

Improved controlled atmosphere high temperature scanning probe microscope

DEFF Research Database (Denmark)

Hansen, Karin Vels; Wu, Yuehua; Jacobsen, Torben

2013-01-01

fuel cells and electrolyzer cells. Here, we report on advanced improvements of our original controlled atmosphere high temperature scanning probe microscope, CAHT-SPM. The new microscope can employ a broad range of the scanning probe techniques including tapping mode, scanning tunneling microscopy......, scanning tunneling spectroscopy, conductive atomic force microscopy, and Kelvin probe force microscopy. The temperature of the sample can be as high as 850 °C. Both reducing and oxidizing gases such as oxygen, hydrogen, and nitrogen can be added in the sample chamber and the oxygen partial pressure (pO2...

On the origin of amplitude reduction mechanism in tapping mode atomic force microscopy

Science.gov (United States)

Keyvani, Aliasghar; Sadeghian, Hamed; Goosen, Hans; van Keulen, Fred

2018-04-01

The origin of amplitude reduction in Tapping Mode Atomic Force Microscopy (TM-AFM) is typically attributed to the shift in resonance frequency of the cantilever due to the nonlinear tip-sample interactions. In this paper, we present a different insight into the same problem which, besides explaining the amplitude reduction mechanism, provides a simple reasoning for the relationship between tip-sample interactions and operation parameters (amplitude and frequency). The proposed formulation, which attributes the amplitude reduction to an interference between the tip-sample and dither force, only deals with the linear part of the system; however, it fully agrees with experimental results and numerical solutions of the full nonlinear model of TM-AFM.

Mapping of Proteomic Composition on the Surfaces of Bacillus spores by Atomic Force Microscopy-based Immunolabeling

Energy Technology Data Exchange (ETDEWEB)

Plomp, M; Malkin, A J

2008-06-02

Atomic force microscopy provides a unique capability to image high-resolution architecture and structural dynamics of pathogens (e.g. viruses, bacteria and bacterial spores) at near molecular resolution in native conditions. Further development of atomic force microscopy in order to enable the correlation of pathogen protein surface structures with specific gene products is essential to understand the mechanisms of the pathogen life cycle. We have applied an AFM-based immunolabeling technique for the proteomic mapping of macromolecular structures through the visualization of the binding of antibodies, conjugated with nanogold particles, to specific epitopes on Bacillus spore surfaces. This information is generated while simultaneously acquiring the surface morphology of the pathogen. The immunospecificity of this labeling method was established through the utilization of specific polyclonal and monoclonal antibodies that target spore coat and exosporium epitopes of Bacillus atrophaeus and Bacillus anthracis spores.

Measurements of stiff-material compliance on the nanoscale using ultrasonic force microscopy

Science.gov (United States)

Dinelli, F.; Biswas, S. K.; Briggs, G. A. D.; Kolosov, O. V.

2000-05-01

Ultrasonic force microscopy (UFM) was introduced to probe nanoscale mechanical properties of stiff materials. This was achieved by vibrating the sample far above the first resonance of the probing atomic force microscope cantilever where the cantilever becomes dynamically rigid. By operating UFM at different set force values, it is possible to directly measure the absolute values of the tip-surface contact stiffness. From this an evaluation of surface elastic properties can be carried out assuming a suitable solid-solid contact model. In this paper we present curves of stiffness as a function of the normal load in the range of 0-300 nN. The dependence of stiffness on the relative humidity has also been investigated. Materials with different elastic constants (such as sapphire lithium fluoride, and silicon) have been successfully differentiated. Continuum mechanics models cannot however explain the dependence of stiffness on the normal force and on the relative humidity. In this high-frequency regime, it is likely that viscous forces might play an important role modifying the tip-surface interaction. Plastic deformation might also occur due to the high strain rates applied when ultrasonically vibrating the sample. Another possible cause of these discrepancies might be the presence of water in between the two bodies in contact organizing in a solidlike way and partially sustaining the load.

Novel operation mode for eliminating influence of inclination angle and friction in atomic force microscopy

International Nuclear Information System (INIS)

Wang, Fei; Wang, Yueyu; Zhou, Faquan; Zhao, Xuezeng

2010-01-01

The accuracy of topography imaging in contact force mode of atomic force microscopy (AFM) depends on the one-to-one corresponding relationship between the cantilever deflection and the tip-sample distance, whereas such a relationship cannot be always achieved in the presence of friction and incline angle of sample surface. Recently, we have developed a novel operation mode in which we keep the van der Waals force as constant instead of the applied normal force, to eliminate the effect of inclination angle and friction on topography imaging in the contact force mode. We have improved our AFM to enable the new operation mode for validation. Comparative experiments have been performed and the results have shown that the effect of friction and inclination angle on topography imaging in contact mode of AFM can be eliminated or at least decreased effectively by working in the new operation mode we present.

Effects of substrates on biofilm formation observed by atomic force microscopy

International Nuclear Information System (INIS)

Oh, Y.J.; Lee, N.R.; Jo, W.; Jung, W.K.; Lim, J.S.

2009-01-01

Formation of biofilm is known to be strongly dependent on substrates including topography, materials, and chemical treatment. In this study, a variety of substrates are tested for understanding biofilm formation. Sheets of aluminum, steel, rubber, and polypropylene have been used to examine their effects on formation of Pseudomonas aeruginosa biofilm. In particular, the morphological variation, transition, and adhesiveness of biofilm were investigated through local measurement by atomic force microscopy (AFM). Mechanism of removing biofilm from adhering to substrate is also analyzed, thus the understanding of the mechanism can be potentially useful to prevent the biofilm formation. The results reveal that formation of biofilm can remain on rough surface regardless of substrates in hot water, which may easily induce extra-polymeric substances detachment from bacterial surface. By probing using AFM, local force-distance characterization of extra-cellular materials extracted from the bacteria can exhibit the progress of the biofilm formation and functional complexities.

Atomic force microscopy observation of lipopolysaccharide-induced cardiomyocyte cytoskeleton reorganization.

Science.gov (United States)

Wang, Liqun; Chen, Tangting; Zhou, Xiang; Huang, Qiaobing; Jin, Chunhua

2013-08-01

We applied atomic force microscopy (AFM) to observe lipopolysaccharide (LPS)-induced intracellular cytoskeleton reorganization in primary cardiomyocytes from neonatal mouse. The nonionic detergent Triton X-100 was used to remove the membrane, soluble proteins, and organelles from the cell. The remaining cytoskeleton can then be directly visualized by AFM. Using three-dimensional technique of AFM, we were able to quantify the changes of cytoskeleton by the "density" and total "volume" of the cytoskeleton fibers. Compared to the control group, the density of cytoskeleton was remarkably decreased and the volume of cytoskeleton was significantly increased after LPS treatment, which suggests that LPS may induce the cytoskeleton reorganization and change the cardiomyocyte morphology. Copyright © 2013 Elsevier Ltd. All rights reserved.

Measuring the elasticity of plant cells with atomic force microscopy.

Science.gov (United States)

Braybrook, Siobhan A

2015-01-01

The physical properties of biological materials impact their functions. This is most evident in plants where the cell wall contains each cell's contents and connects each cell to its neighbors irreversibly. Examining the physical properties of the plant cell wall is key to understanding how plant cells, tissues, and organs grow and gain the shapes important for their respective functions. Here, we present an atomic force microscopy-based nanoindentation method for examining the elasticity of plant cells at the subcellular, cellular, and tissue level. We describe the important areas of experimental design to be considered when planning and executing these types of experiments and provide example data as illustration. Copyright © 2015 Elsevier Inc. All rights reserved.

Simulated non-contact atomic force microscopy for GaAs surfaces based on real-space pseudopotentials

International Nuclear Information System (INIS)

Kim, Minjung; Chelikowsky, James R.

2014-01-01

We simulate non-contact atomic force microscopy (AFM) with a GaAs(1 1 0) surface using a real-space ab initio pseudopotential method. While most ab initio simulations include an explicit model for the AFM tip, our method does not introduce the tip modeling step. This approach results in a considerable reduction of computational work, and also provides complete AFM images, which can be directly compared to experiment. By analyzing tip-surface interaction forces in both our results and previous ab initio simulations, we find that our method provides very similar force profile to the pure Si tip results. We conclude that our method works well for systems in which the tip is not chemically active.

Length-extension resonator as a force sensor for high-resolution frequency-modulation atomic force microscopy in air.

Science.gov (United States)

Beyer, Hannes; Wagner, Tino; Stemmer, Andreas

2016-01-01

Frequency-modulation atomic force microscopy has turned into a well-established method to obtain atomic resolution on flat surfaces, but is often limited to ultra-high vacuum conditions and cryogenic temperatures. Measurements under ambient conditions are influenced by variations of the dew point and thin water layers present on practically every surface, complicating stable imaging with high resolution. We demonstrate high-resolution imaging in air using a length-extension resonator operating at small amplitudes. An additional slow feedback compensates for changes in the free resonance frequency, allowing stable imaging over a long period of time with changing environmental conditions.

Dissipative and electrostatic force spectroscopy of indium arsenide quantum dots by non-contact atomic force microscopy

Science.gov (United States)

Stomp, Romain-Pierre

This thesis is devoted to the studies of self-assembled InAs quantum dots (QD) by low-temperature Atomic Force Microscopy (AFM) in frequency modulation mode. Several spectroscopic methods are developed to investigate single electron charging from a two-dimensional electron gas (2DEG) to an individual InAs QD. Furthermore, a new technique to measure the absolute tip-sample capacitance is also demonstrated. The main observables are the electrostatic force between the metal-coated AFM tip and sample as well as the sample-induced energy dissipation, and therefore no tunneling current has to be collected at the AFM tip. Measurements were performed by recording simultaneously the shift in the resonant frequency and the Q-factor degradation of the oscillating cantilever either as a function of tip-sample voltage or distance. The signature of single electron charging was detected as an abrupt change in the frequency shift as well as corresponding peaks in the dissipation. The main experimental features in the force agree well with the semi-classical theory of Coulomb blockade by considering the free energy of the system. The observed dissipation peaks can be understood as a back-action effect on the oscillating cantilever beam due to the fluctuation in time of electrons tunneling back and forth between the 2DEG and the QD. It was also possible to extract the absolute value of the tip-sample capacitance, as a consequence of the spectroscopic analysis of the electrostic force as a function of tip-sample distance for different values of the applied voltage. At the same time, the contact potential difference and the residual non-capacitive force could also be determined as a function of tip-sample distance.

Rayleigh-Taylor and Kelvin-Helmholtz instabilities in targets accelerated by laser ablation

International Nuclear Information System (INIS)

Emery, M.H.; Gardner, J.H.; Boris, J.P.

1982-01-01

With use of the fast2d laser-shell model, the acceleration of a 20-μm-thick plastic foil up to 160 km/s has been simulated. It is possible to follow the Rayleigh-Taylor bubble-and-spike development far into the nonlinear regime and beyond the point of foil fragmentation. Strong shear flow develops which evolves into the Kelvin-Helmholtz instability. The Kelvin-Helmholtz instability causes the tips of the spikes to widen and as a result reduce their rate of ''fall.''

Convergent Inquiry in Science & Engineering: The Use of Atomic Force Microscopy in a Biology Class

Science.gov (United States)

Lee, Il-Sun; Byeon, Jung-Ho; Kwon, Yong-Ju

2013-01-01

The purpose of this study was to design a teaching method suitable for science high school students using atomic force microscopy. During their scientific inquiry procedure, high school students observed a micro-nanostructure of a biological sample, which is unobservable via an optical microscope. The developed teaching method enhanced students'…

The Use of Atomic Force Microscopy as a Technique for the Identification of Cancerous Cells

International Nuclear Information System (INIS)

Lekka, M.

2007-11-01

The monograph presents the use of atomic force microscopy (AFM) as a tool for the identification of cancerous cells by studies of the expression of different types of molecules directly on the surface of living cells. The full quantitative description (that is not accessible by other techniques) performed for a given type of molecular interactions has been obtained by using the following quantities: an unbinding force, probability, rupture length and the effective spring constant taking into account the stiffness of a single complex. All, these parameters were extracted from AFM measurements The analysis of the interaction forces performed by AFM allows the quantitative determination of: i) the static properties of a single molecular complex where its strength of interaction and stiffness of the studied complex can be obtained, ii) dynamic properties, on the basis of which the kinetic properties of the unbinding process can be delivered, and iii) properties of adhesion clusters, where the interrelation between single complexes can be characterized, in particular the mechanism of the unbinding can be obtained. The presented characterization of the interaction force between single molecules demonstrates that atomic force microscopy can be used as exceptional technique to study the expression of molecules on a cell surface. Such measurements are not limited to a typical interactions occurring between single molecules but also it is possible to study the interactions between parts of molecules. The results presented in this monograph point to a novel approach to identify cancer-related changes in a quantitative way what can be used for describing and confirming the pathological state of a single cell. (author)

Investigation into local cell mechanics by atomic force microscopy mapping and optical tweezer vertical indentation.

Science.gov (United States)

Coceano, G; Yousafzai, M S; Ma, W; Ndoye, F; Venturelli, L; Hussain, I; Bonin, S; Niemela, J; Scoles, G; Cojoc, D; Ferrari, E

2016-02-12

Investigating the mechanical properties of cells could reveal a potential source of label-free markers of cancer progression, based on measurable viscoelastic parameters. The Young's modulus has proved to be the most thoroughly studied so far, however, even for the same cell type, the elastic modulus reported in different studies spans a wide range of values, mainly due to the application of different experimental conditions. This complicates the reliable use of elasticity for the mechanical phenotyping of cells. Here we combine two complementary techniques, atomic force microscopy (AFM) and optical tweezer microscopy (OTM), providing a comprehensive mechanical comparison of three human breast cell lines: normal myoepithelial (HBL-100), luminal breast cancer (MCF-7) and basal breast cancer (MDA-MB-231) cells. The elastic modulus was measured locally by AFM and OTM on single cells, using similar indentation approaches but different measurement parameters. Peak force tapping AFM was employed at nanonewton forces and high loading rates to draw a viscoelastic map of each cell and the results indicated that the region on top of the nucleus provided the most meaningful results. OTM was employed at those locations at piconewton forces and low loading rates, to measure the elastic modulus in a real elastic regime and rule out the contribution of viscous forces typical of AFM. When measured by either AFM or OTM, the cell lines' elasticity trend was similar for the aggressive MDA-MB-231 cells, which were found to be significantly softer than the other two cell types in both measurements. However, when comparing HBL-100 and MCF-7 cells, we found significant differences only when using OTM.

Magni: A Python Package for Compressive Sampling and Reconstruction of Atomic Force Microscopy Images

DEFF Research Database (Denmark)

Oxvig, Christian Schou; Pedersen, Patrick Steffen; Arildsen, Thomas

2014-01-01

Magni is an open source Python package that embraces compressed sensing and Atomic Force Microscopy (AFM) imaging techniques. It provides AFM-specific functionality for undersampling and reconstructing images from AFM equipment and thereby accelerating the acquisition of AFM images. Magni also pr...... as a convenient platform for researchers in compressed sensing aiming at obtaining a high degree of reproducibility of their research....

Atomic force microscopy studies on molybdenum disulfide flakes as sodium-ion anodes.

Science.gov (United States)

Lacey, Steven D; Wan, Jiayu; von Wald Cresce, Arthur; Russell, Selena M; Dai, Jiaqi; Bao, Wenzhong; Xu, Kang; Hu, Liangbing

2015-02-11

A microscale battery comprised of mechanically exfoliated molybdenum disulfide (MoS2) flakes with copper connections and a sodium metal reference was created and investigated as an intercalation model using in situ atomic force microscopy in a dry room environment. While an ethylene carbonate-based electrolyte with a low vapor pressure allowed topographical observations in an open cell configuration, the planar microbattery was used to conduct in situ measurements to understand the structural changes and the concomitant solid electrolyte interphase (SEI) formation at the nanoscale. Topographical observations demonstrated permanent wrinkling behavior of MoS2 electrodes upon sodiation at 0.4 V. SEI formation occurred quickly on both flake edges and planes at voltages before sodium intercalation. Force spectroscopy measurements provided quantitative data on the SEI thickness for MoS2 electrodes in sodium-ion batteries for the first time.

Tunable atomic force microscopy bias lithography on electron beam induced carbonaceous platforms

Directory of Open Access Journals (Sweden)

Narendra Kurra

2013-09-01

Full Text Available Tunable local electrochemical and physical modifications on the carbonaceous platforms are achieved using Atomic force microscope (AFM bias lithography. These carbonaceous platforms are produced on Si substrate by the technique called electron beam induced carbonaceous deposition (EBICD. EBICD is composed of functionalized carbon species, confirmed through X-ray photoelectron spectroscopy (XPS analysis. AFM bias lithography in tapping mode with a positive tip bias resulted in the nucleation of attoliter water on the EBICD surface under moderate humidity conditions (45%. While the lithography in the contact mode with a negative tip bias caused the electrochemical modifications such as anodic oxidation and etching of the EBICD under moderate (45% and higher (60% humidity conditions respectively. Finally, reversible charge patterns are created on these EBICD surfaces under low (30% humidity conditions and investigated by means of electrostatic force microscopy (EFM.

Technique to measure contact angle of micro/nanodroplets using atomic force microscopy

International Nuclear Information System (INIS)

Jung, Yong Chae; Bhushan, Bharat

2008-01-01

Contact angle is the primary parameter that characterizes wetting; however, the measurement techniques have been limited to droplets with a diameter as low as about 50 μm. The authors developed an atomic force microscopy-based technique to measure the contact angle of micro- and nanodroplets deposited using a modified nanoscale dispensing tip. The obtained contact angle results were compared with those of a macrodroplet (2.1 mm diameter). It was found that the contact angle on various surfaces decreases with decreasing the droplet size

Implementing atomic force microscopy (AFM) for studying kinetics of gold nanoparticle's growth

DEFF Research Database (Denmark)

Georgiev, P.; Bojinova, A.; Kostova, B.

2013-01-01

In a novel experimental approach Atomic Force Microscopy (AFM) was applied as a tool for studying the kinetics of gold nanoparticle growth. The gold nanoparticles were obtained by classical Turkevich citrate synthesis at two different temperatures. From the analysis of AFM images during...... the synthesis process the nanoparticle s' sizes were obtained. To demonstrate the applicability and the reliability of the proposed experimental approach we studied the nanoparticles growth at two different temperatures by spectrophotometric measurements and compared them with the results from AFM experimental...

Molecular dynamics simulation of amplitude modulation atomic force microscopy

International Nuclear Information System (INIS)

Hu, Xiaoli; Martini, Ashlie; Egberts, Philip; Dong, Yalin

2015-01-01

Molecular dynamics (MD) simulations were used to model amplitude modulation atomic force microscopy (AM-AFM). In this novel simulation, the model AFM tip responds to both tip–substrate interactions and to a sinusoidal excitation signal. The amplitude and phase shift of the tip oscillation observed in the simulation and their variation with tip–sample distance were found to be consistent with previously reported trends from experiments and theory. These simulation results were also fit to an expression enabling estimation of the energy dissipation, which was found to be smaller than that in a corresponding experiment. The difference was analyzed in terms of the effects of tip size and substrate thickness. Development of this model is the first step toward using MD to gain insight into the atomic-scale phenomena that occur during an AM-AFM measurement. (paper)

Detecting onset of chain scission and crosslinking of γ-ray irradiated elastomer surfaces using frictional force microscopy

International Nuclear Information System (INIS)

Banerjee, S; Sinha, N K; Gayathri, N; Ponraju, D; Dash, S; Tyagi, A K; Raj, Baldev

2007-01-01

We report here that atomic force microscopy (AFM) in frictional force mode can be used to detect the onset of chain scission and crosslinking in polymeric and macromolecular samples upon irradiation. A systematic investigation to detect chain scission and crosslinking of two elastomers (1) ethylene-propylene-diene monomer rubber and (2) fluorocarbon rubber, upon γ-ray irradiation has been carried out using frictional force microscopy (FFM). From the AFM results we observed that both the elastomers show a systematic smoothening of its surfaces, as the γ-ray dose rate increases. However, the frictional property studied using FFM of the sample surfaces show an initial increase and then a decrease as a function of dose rate. This behaviour of increase in its frictional property has been attributed to the onset of chain scission, and the subsequent decrease in friction has been attributed to the onset of crosslinking of the polymer chains. The evaluated qualitative and semi-quantitative changes observed in the overall frictional property as a function of the γ-ray dose rate for the two elastomers are presented in this paper

Detecting onset of chain scission and crosslinking of {gamma}-ray irradiated elastomer surfaces using frictional force microscopy

Energy Technology Data Exchange (ETDEWEB)

Banerjee, S [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 TN (India); Sinha, N K [Innovative Design Engineering and Synthesis Section, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 TN (India); Gayathri, N [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 TN (India); Ponraju, D [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 TN (India); Dash, S [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 TN (India); Tyagi, A K [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 TN (India); Raj, Baldev [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 TN (India)

2007-02-07

We report here that atomic force microscopy (AFM) in frictional force mode can be used to detect the onset of chain scission and crosslinking in polymeric and macromolecular samples upon irradiation. A systematic investigation to detect chain scission and crosslinking of two elastomers (1) ethylene-propylene-diene monomer rubber and (2) fluorocarbon rubber, upon {gamma}-ray irradiation has been carried out using frictional force microscopy (FFM). From the AFM results we observed that both the elastomers show a systematic smoothening of its surfaces, as the {gamma}-ray dose rate increases. However, the frictional property studied using FFM of the sample surfaces show an initial increase and then a decrease as a function of dose rate. This behaviour of increase in its frictional property has been attributed to the onset of chain scission, and the subsequent decrease in friction has been attributed to the onset of crosslinking of the polymer chains. The evaluated qualitative and semi-quantitative changes observed in the overall frictional property as a function of the {gamma}-ray dose rate for the two elastomers are presented in this paper.

G-mode magnetic force microscopy: Separating magnetic and electrostatic interactions using big data analytics

Energy Technology Data Exchange (ETDEWEB)

Collins, Liam; Belianinov, Alex; Kalinin, Sergei V.; Jesse, Stephen [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Institute for Functional Imaging of Materials, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Proksch, Roger [Asylum Research, An Oxford Instruments Company, Santa Barbara, California 93117 (United States); Zuo, Tingting [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Deptarment of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996-2200 (United States); Zhang, Yong [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Liaw, Peter K. [Deptarment of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996-2200 (United States)

2016-05-09

In this work, we develop a full information capture approach for Magnetic Force Microscopy (MFM), referred to as generalized mode (G-Mode) MFM. G-Mode MFM acquires and stores the full data stream from the photodetector, captured at sampling rates approaching the intrinsic photodiode limit. The data can be subsequently compressed, denoised, and analyzed, without information loss. Here, G-Mode MFM is implemented and compared to the traditional heterodyne-based MFM on model systems, including domain structures in ferromagnetic Yttrium Iron Garnet and the electronically and magnetically inhomogeneous high entropy alloy, CoFeMnNiSn. We investigate the use of information theory to mine the G-Mode MFM data and demonstrate its usefulness for extracting information which may be hidden in traditional MFM modes, including signatures of nonlinearities and mode-coupling phenomena. Finally, we demonstrate detection and separation of magnetic and electrostatic tip-sample interactions from a single G-Mode image, by analyzing the entire frequency response of the cantilever. G-Mode MFM is immediately implementable on any atomic force microscopy platform and as such is expected to be a useful technique for probing spatiotemporal cantilever dynamics and mapping material properties, as well as their mutual interactions.

Investigating the crystal growth behavior of biodegradable polymer blend thin films using in situ atomic force microscopy

CSIR Research Space (South Africa)

Malwela, T

2014-01-01

Full Text Available This article reports the crystal growth behavior of biodegradable polylactide (PLA)/poly[(butylene succinate)-co-adipate] (PBSA) blend thin films using atomic force microscopy (AFM). Currently, polymer thin films have received increased research...

Dual-tip magnetic force microscopy with suppressed influence on magnetically soft samples

International Nuclear Information System (INIS)

Precner, Marián; Fedor, Ján; Šoltýs, Ján; Cambel, Vladimír

2015-01-01

Standard magnetic force microscopy (MFM) is considered as a powerful tool used for magnetic field imaging at nanoscale. The method consists of two passes realized by the magnetic tip. Within the first one, the topography pass, the magnetic tip directly touches the magnetic sample. Such contact perturbs the magnetization of the sample explored. To avoid the sample touching the magnetic tip, we present a new approach to magnetic field scanning by segregating the topological and magnetic scans with two different tips located on a cut cantilever. The approach minimizes the disturbance of sample magnetization, which could be a major problem in conventional MFM images of soft magnetic samples. By cutting the cantilever in half using the focused ion beam technique, we create one sensor with two different tips—one tip is magnetized, and the other one is left non-magnetized. The non-magnetized tip is used for topography and the magnetized one for the magnetic field imaging. The method developed we call dual-tip magnetic force microscopy (DT-MFM). We describe in detail the dual-tip fabrication process. In the experiments, we show that the DT-MFM method reduces significantly the perturbations of the magnetic tip as compared to the standard MFM method. The present technique can be used to investigate microscopic magnetic domain structures in a variety of magnetic samples and is relevant in a wide range of applications, e.g., data storage and biomedicine. (paper)

Nano-contact microscopy of supracrystals

Directory of Open Access Journals (Sweden)

Adam Sweetman

2015-05-01

Full Text Available Background: Highly ordered three-dimensional colloidal crystals (supracrystals comprised of 7.4 nm diameter Au nanocrystals (with a 5% size dispersion have been imaged and analysed using a combination of scanning tunnelling microscopy and dynamic force microscopy.Results: By exploring the evolution of both the force and tunnel current with respect to tip–sample separation, we arrive at the surprising finding that single nanocrystal resolution is readily obtained in tunnelling microscopy images acquired more than 1 nm into the repulsive (i.e., positive force regime of the probe–nanocrystal interaction potential. Constant height force microscopy has been used to map tip–sample interactions in this regime, revealing inhomogeneities which arise from the convolution of the tip structure with the ligand distribution at the nanocrystal surface.Conclusion: Our combined STM–AFM measurements show that the contrast mechanism underpinning high resolution imaging of nanoparticle supracrystals involves a form of nanoscale contact imaging, rather than the through-vacuum tunnelling which underpins traditional tunnelling microscopy and spectroscopy.

Evidence of the no-slip boundary condition of water flow between hydrophilic surfaces using atomic force microscopy.

Science.gov (United States)

Maali, Abdelhamid; Wang, Yuliang; Bhushan, Bharat

2009-10-20

In this study we present measurements of the hydrodynamic force exerted on a glass sphere glued to an atomic force microscopy (AFM) cantilever approaching a mica surface in water. A large sphere was used to reduce the impact of the cantilever beam on the measurement. An AFM cantilever with large stiffness was used to accurately determine the actual contact position between the sphere and the sample surface. The measured hydrodynamic force with different approach velocities is in good agreement with the Taylor force calculated in the lubrication theory with the no-slip boundary conditions, which verifies that there is no boundary slip on the glass and mica surfaces. Moreover, a detailed procedure of how to subtract the electrostatic double-layer force is presented.

Deflection-voltage curve modelling in atomic force microscopy and its use in DC electrostatic manipulation of gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Toset, J; Casuso, I; Samitier, J; Gomila, G [Departament d' Electronica, Universitat de Barcelona and Laboratori de Nanobioenginyeria-CREBEC, Parc CientIfic de Barcelona, C/Josep Samitier 1-5, 08028 Barcelona (Spain)

2007-01-10

A model of deflection-voltage curves in atomic force microscopy and its use in DC electrostatic nanomanipulation experiments are presented. The proposed model predicts the deflection of the atomic force microscope probe as a function of the applied probe-substrate voltage, as well as the distance and voltage at which the tip collapses irreversibly onto the substrate due to electrostatic forces. The model is verified experimentally and its use in DC electrostatic manipulation of 25 nm radius gold nanoparticles is demonstrated.

KELVIN rare gas time-of-flight program

International Nuclear Information System (INIS)

Vernon, M.

1981-03-01

The purpose of this appendix is to explain in detail the procedure for performing time-of-flight (TOF) calibration measurements. The result of the calibration measurements is to assign a correct length (L) to the path the molecules travel in a particular experimental configuration. In conjunction with time information (t) a velocity distribution (L/t) can then be determined. The program KELVIN is listed

A serial-kinematic nanopositioner for high-speed atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Wadikhaye, Sachin P., E-mail: sachin.wadikhaye@uon.edu.au; Yong, Yuen Kuan; Reza Moheimani, S. O. [School of Electrical Engineering and Computer Science, The University of Newcastle, Callaghan, NSW (Australia)

2014-10-15

A flexure-guided serial-kinematic XYZ nanopositioner for high-speed Atomic Force Microscopy is presented in this paper. Two aspects influencing the performance of serial-kinematic nanopositioners are studied in this work. First, mass reduction by using tapered flexures is proposed to increased the natural frequency of the nanopositioner. 25% increase in the natural frequency is achieved due to reduced mass with tapered flexures. Second, a study of possible sensor positioning in a serial-kinematic nanopositioner is presented. An arrangement of sensors for exact estimation of cross-coupling is incorporated in the proposed design. A feedforward control strategy based on phaser approach is presented to mitigate the dynamics and nonlinearity in the system. Limitations in design approach and control strategy are discussed in the Conclusion.

A serial-kinematic nanopositioner for high-speed atomic force microscopy

International Nuclear Information System (INIS)

Wadikhaye, Sachin P.; Yong, Yuen Kuan; Reza Moheimani, S. O.

2014-01-01

A flexure-guided serial-kinematic XYZ nanopositioner for high-speed Atomic Force Microscopy is presented in this paper. Two aspects influencing the performance of serial-kinematic nanopositioners are studied in this work. First, mass reduction by using tapered flexures is proposed to increased the natural frequency of the nanopositioner. 25% increase in the natural frequency is achieved due to reduced mass with tapered flexures. Second, a study of possible sensor positioning in a serial-kinematic nanopositioner is presented. An arrangement of sensors for exact estimation of cross-coupling is incorporated in the proposed design. A feedforward control strategy based on phaser approach is presented to mitigate the dynamics and nonlinearity in the system. Limitations in design approach and control strategy are discussed in the Conclusion

Improving tapping mode atomic force microscopy with piezoelectric cantilevers

International Nuclear Information System (INIS)