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Sample records for scanning tunneling microscopy

  1. Introduction to scanning tunneling microscopy

    CERN Document Server

    Chen, C Julian

    2008-01-01

    The scanning tunneling and the atomic force microscope, both capable of imaging individual atoms, were crowned with the Physics Nobel Prize in 1986, and are the cornerstones of nanotechnology today. This is a thoroughly updated version of this 'bible' in the field.

  2. Investigation into scanning tunnelling luminescence microscopy

    CERN Document Server

    Manson-Smith, S K

    2001-01-01

    This work reports on the development of a scanning tunnelling luminescence (STL) microscope and its application to the study of Ill-nitride semiconductor materials used in the production of light emitting devices. STL microscopy is a technique which uses the high resolution topographic imaging capabilities of the scanning tunnelling microscope (STM) to generate high resolution luminescence images. The STM tunnelling current acts as a highly localised source of electrons (or holes) which generates luminescence in certain materials. Light generated at the STM tunnelling junction is collected concurrently with the height variation of the tunnelling probe as it is scanned across a sample surface, producing simultaneous topographic and luminescence images. Due to the very localised excitation source, high resolution luminescence images can be obtained. Spectroscopic resolution can be obtained by using filters. Additionally, the variation of luminescence intensity with tunnel current and with bias voltage can provi...

  3. Towards high-speed scanning tunneling microscopy

    NARCIS (Netherlands)

    Tabak, Femke Chantal

    2013-01-01

    In this thesis, two routes towards high-speed scanning tunneling microscopy (STM) are described. The first possibility for high-speed scanning that is discussed is the use of MEMS (Micro-Electro Mechanical Systems) devices as high-speed add-ons in STM microscopes. The functionality of these devices

  4. Spin-polarized scanning tunnelling microscopy

    CERN Document Server

    Bode, M

    2003-01-01

    The recent experimental progress in spin-polarized scanning tunnelling microscopy (SP-STM) - a magnetically sensitive imaging technique with ultra-high resolution - is reviewed. The basics of spin-polarized electron tunnelling are introduced as they have been investigated in planar tunnel junctions for different electrode materials, i.e. superconductors, optically excited GaAs, and ferromagnets. It is shown that ferromagnets and antiferromagnets are suitable tip materials for the realization of SP-STM. Possible tip designs and modes of operations are discussed for both classes of materials. The results of recent spatially resolved measurements as performed with different magnetic probe tips and using different modes of operation are reviewed and discussed in terms of applicability to surfaces, thin films, and nanoparticles. The limits of spatial resolution, and the impact of an external magnetic field on the imaging process.

  5. Scanning tunneling microscopy II further applications and related scanning techniques

    CERN Document Server

    Güntherodt, Hans-Joachim

    1995-01-01

    Scanning Tunneling Microscopy II, like its predecessor, presents detailed and comprehensive accounts of the basic principles and broad range of applications of STM and related scanning probe techniques. The applications discussed in this volume come predominantly from the fields of electrochemistry and biology. In contrast to those described in STM I, these studies may be performed in air and in liquids. The extensions of the basic technique to map other interactions are described in chapters on scanning force microscopy, magnetic force microscopy, and scanning near-field optical microscopy, together with a survey of other related techniques. Also described here is the use of a scanning proximal probe for surface modification. Together, the two volumes give a comprehensive account of experimental aspects of STM. They provide essential reading and reference material for all students and researchers involved in this field. In this second edition the text has been updated and new methods are discussed.

  6. Scanning tunneling microscopy II further applications and related scanning techniques

    CERN Document Server

    Güntherodt, Hans-Joachim

    1992-01-01

    Scanning Tunneling Microscopy II, like its predecessor, presents detailed and comprehensive accounts of the basic principles and broad range of applications of STM and related scanning probe techniques. The applications discussed in this volume come predominantly from the fields of electrochemistry and biology. In contrast to those described in Vol. I, these sudies may be performed in air and in liquids. The extensions of the basic technique to map other interactions are described inchapters on scanning force microscopy, magnetic force microscopy, scanning near-field optical microscopy, together with a survey of other related techniques. Also described here is the use of a scanning proximal probe for surface modification. Togehter, the two volumes give a comprehensive account of experimental aspcets of STM. They provide essentialreading and reference material for all students and researchers involvedin this field.

  7. New Applications of Scanning Tunneling Microscopy

    Science.gov (United States)

    Smith, Douglas Philip Edward

    This dissertation describes the application of the scanning tunneling microscope (STM) technique to four new fields of study: thin organic films, phonon spectroscopy of bulk surfaces, the vibrational spectroscopy of molecules, and the tribological forces which occur between STM tip and sample. Images with atomic resolution were obtained with speeds approaching video rates. Two types of microscopes were used: one operated at room temperature in air, another at 4.2K in liquid helium. At room temperature, the STM was able to image molecules of cadmium arachidate deposited onto graphite by the Langmuir-Blodgett technique. The packing of molecules in the lipid bilayer was found to be partially ordered, with density of 1 molecule per 19.4 square angstroms. At liquid-helium temperature, inelastic electron processes were detected, and it was possible to determine within an area of a few square angstroms where the vibrational excitations occurred. On a bare graphite substrate, phonons of the sample and tip caused step increases in the tunneling conductivity at the phonon energies. Molecules of sorbic acid could be resolved when deposited onto graphite, and these molecules caused spatially localized peaks in conductivity at the energies of the bond vibrations. Although the STM is usually considered a non-contact instrument, under certain circumstances the tip and sample exerted strong forces on each other. With a tungsten tip and a graphite sample, friction and mechanical deformations on the atomic scale were observed.

  8. Ultrafast terahertz scanning tunneling microscopy with atomic resolution

    DEFF Research Database (Denmark)

    Jelic, Vedran; Iwaszczuk, Krzysztof; Nguyen, Peter H.

    2016-01-01

    We demonstrate that ultrafast terahertz scanning tunneling microscopy (THz-STM) can probe single atoms on a silicon surface with simultaneous sub-nanometer and sub-picosecond spatio-temporal resolution. THz-STM is established as a new technique for exploring high-field non-equilibrium tunneling...

  9. Surface Analysis by Scanning Tunneling Microscopy

    Science.gov (United States)

    Coury, Louis A., Jr.; Johnson, Mario; Murphy, Tammy J.

    1995-12-01

    In both student projects a Burleigh Instruments ARIS-2200E STM was employed to image polycrystalline gold electrodes before and after deposition of a second metal onto the surface. Students prepared their own tungsten STM tips using an A.C.-etching procedure in 5% NaNO2. The electrodes used were available commercailly (AAI-AbTech, Yardley, PA) and consisted of 1000 of Au over a 100 adhesion layer of Ti on electronics-grade borosilicate glass. Electrodes were affixed to the STM sample holder using conductive carbon tape (SPI, West Chester, PA) and imaged in air. Modified electrodes were prepared by sonochemical deposition of 300 nm-Cu particles onto the Au surface in a procedure described elsewhere (2) or by the electrolytic deposition of various metals used in dental amalgams from acidic media using a Cypress Systems CS-1087 potentiostat. ResultsIn a typical image obtained for an unmodified Au surface (see image below), small crystallites (~500 to 1000 in diameter) of Au formed during the sputtering process during electrode fabrication are clearly visible. Images of modified electrodes (not shown) always show a markedly different morphology, with visible characteristic surface features ranging in size from hundreds of nanometers to several microns. The concepts students learn in these studies include electron tunneling, electroplating, nucleation phenomena, and amalgam chemistry. Although primarily touted as a method for atomic resolution imaging, STM clearly has utility for examining surfaces with features in the 100-nm to 1-micrometer size regime. Because of the recent availability of inexpensive instruments with user-friendly software, we encourage others to consider incorporating STM into the undergraduate curriculum. AcknowledgmentThis project was supported partially by a grant, DUE-9351426, from the National Science Foundation Division of Undergraduate Education Instrumentation and Laboratory Improvement Program. Literature Cited Lederman, L. Science 1991

  10. Sub-Kelvin scanning tunneling microscopy on magnetic molecules

    OpenAIRE

    Zhang, Lei

    2012-01-01

    Magnetic molecules have attracted lots interest. In this work, an ultra-stable and low noise scanning tunneling microscopy operating at 400 mK using He-3 (930 mK using He-4) has been developed. The magnetic behavior of different magnetic molecules on substrates, especially the exchange interaction between the magnetic ions, the magnetic anisotropy on the surface, the magnetic excitations as well as the Kondo effect, were studied by using STM.

  11. 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

  12. Scanning tunneling microscopy III theory of STM and related scanning probe methods

    CERN Document Server

    Güntherodt, Hans-Joachim

    1996-01-01

    Scanning Tunneling Microscopy III provides a unique introduction to the theoretical foundations of scanning tunneling microscopy and related scanning probe methods. The different theoretical concepts developed in the past are outlined, and the implications of the theoretical results for the interpretation of experimental data are discussed in detail. Therefore, this book serves as a most useful guide for experimentalists as well as for theoreticians working in the filed of local probe methods. In this second edition the text has been updated and new methods are discussed.

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

    Science.gov (United States)

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

    2015-12-01

    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.

  14. Probing the surface chemistry of polycrystalline ZnO with scanning tunneling microscopy and tunneling spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rohrer, G.S.; Bonnell, D.A. (Univ. of Pennsylvania, Philadelphia (United States))

    This paper describes the use of scanning tunneling microscopy and spatially resolved tunneling spectroscopy to examine polycrystalline ZnO surface in ultrahigh vacuum after bake-out, after a low temperature anneal that cleaned the surface, after a high temperature anneal, which segregated bismuth to the surface, after being dosed with O{sub 2} and H{sub 2}O, and after exposure to air. The tunneling spectra depend both on the proximity to structural features, such as grain boundaries, and on the chemical composition of the surface. For example, the segregation of bismuth to the surface causes the tunneling spectra to have a p-type rectification. Our results also indicate that the rectification of tunneling spectra acquired in air is caused by surface hydration and that images of surfaces that have not been heated in vacuum have inferior resolution due to a reduction in the height of the apparent tunnel barrier. Spatially resolved tunneling spectroscopy has been used to demonstrate that surface hydration has a greater effect on the crystallite surfaces than on the grain boundary surfaces.

  15. Apparent Barrier Height in Scanning Tunneling Microscopy Revisited

    DEFF Research Database (Denmark)

    Olesen, L.; Brandbyge, Mads; Sørensen, Mads Reinholdt

    1996-01-01

    The apparent barrier height phi(ap), that is, the rate of change of the logarithm of the conductance with tip-sample separation in a scanning tunneling microscope (STM), has been measured for Ni, Pt, and Au single crystal surfaces. The results show that phi(ap) is constant until point contact is ...

  16. Observation of diamond turned OFHC copper using Scanning Tunneling Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Grigg, D.A.; Russell, P.E.; Dow, T.A.

    1988-12-01

    Diamond turned OFHC copper samples have been observed within the past few months using the Scanning Tunneling Microscope. Initial results have shown evidence of artifacts which may be used to better understand the diamond turning process. The STM`s high resolution capability and three dimensional data representation allows observation and study of surface features unobtainable with conventional profilometry systems. Also, the STM offers a better quantitative means by which to analyze surface structures than the SEM. This paper discusses findings on several diamond turned OFHC copper samples having different cutting conditions. Each sample has been cross referenced using STM and SEM.

  17. Optical characterication of probes for photon scanning tunnelling microscopy

    DEFF Research Database (Denmark)

    Vohnsen, Brian; Bozhevolnyi, Sergey I.

    1999-01-01

    The photon scanning tunnelling microscope is a well-established member of the family of scanning near-field optical microscopes used for optical imaging at the sub-wavelength scale. The quality of the probes, typically pointed uncoated optical fibres, used is however difficult to evaluate...... in a direct manner and has most often been inferred from the apparent quality of recorded optical images. Complicated near-field optical imaging characteristics, together with the possibility of topographically induced artefacts, however, has increased demands for a more reliable probe characterization...... technique. Here we present experimental results obtained for optical characterization of two different probes by imaging of a well-specified near-field intensity distribution at various spatial frequencies. In particular, we observe that a sharply pointed dielectric probe can be highly suitable for imaging...

  18. Sequencing of adenine in DNA by scanning tunneling microscopy

    Science.gov (United States)

    Tanaka, Hiroyuki; Taniguchi, Masateru

    2017-08-01

    The development of DNA sequencing technology utilizing the detection of a tunnel current is important for next-generation sequencer technologies based on single-molecule analysis technology. Using a scanning tunneling microscope, we previously reported that dI/dV measurements and dI/dV mapping revealed that the guanine base (purine base) of DNA adsorbed onto the Cu(111) surface has a characteristic peak at V s = -1.6 V. If, in addition to guanine, the other purine base of DNA, namely, adenine, can be distinguished, then by reading all the purine bases of each single strand of a DNA double helix, the entire base sequence of the original double helix can be determined due to the complementarity of the DNA base pair. Therefore, the ability to read adenine is important from the viewpoint of sequencing. Here, we report on the identification of adenine by STM topographic and spectroscopic measurements using a synthetic DNA oligomer and viral DNA.

  19. Active current-noise cancellation for Scanning Tunneling Microscopy

    Science.gov (United States)

    Pabbi, Lavish; Shoop, Conner; Banerjee, Riju; Dusch, Bill; Hudson, E. W.

    The high sensitivity of the scanning tunneling microscope (STM) poses a barrier to its use in a noisy environment. Vibrational noise, whether structural or acoustic in source, manifests as relative motion between the probe tip and the sample, then appearing in the Z feedback that tries to cancel it. Here we describe an active noise cancellation process that nullifies this motion by adding a drive signal into the existing Z feedback loop. The drive is digitally calculated by actively monitoring vibrations measured by an accelerometer placed in-situ close to the STM head. By transferring the vibration cancellation effort to this drive signal, vibration-created noise in the Z-feedback (during topography) or current (during spectroscopy) is significantly reduced. This inexpensive and easy solution, requiring no major instrumental modifications, is ideal for those looking to place their STM in a noisier environment, for example in the presence of active refrigeration systems (e.g. pulse tube cryocoolers) or coupled to high-vibration instrumentation. This material is based upon work supported by the National Science Foundation under Grant No. 1229138.

  20. Scanning tunneling microscopy I general principles and applications to clean and adsorbate-covered surfaces

    CERN Document Server

    Wiesendanger, Roland

    1992-01-01

    Scanning Tunneling Microscopy I provides a unique introduction to a novel and fascinating technique that produces beautiful images of nature on an atomic scale. It is the first of three volumes that together offer a comprehensive treatment of scanning tunneling microscopy, its diverse applications, and its theoretical treatment. In this volume the reader will find a detailed description of the technique itself and of its applications to metals, semiconductors, layered materials, adsorbed molecules and superconductors. In addition to the many representative results reviewed, extensive references to original work will help to make accessible the vast body of knowledge already accumulated in this field.

  1. Scanning tunneling microscopy III theory of STM and related scanning probe methods

    CERN Document Server

    Güntherodt, Hans-Joachim

    1993-01-01

    While the first two volumes on Scanning Tunneling Microscopy (STM) and its related scanning probe (SXM) methods have mainly concentrated on intro­ ducing the experimental techniques, as well as their various applications in different research fields, this third volume is exclusively devoted to the theory of STM and related SXM methods. As the experimental techniques including the reproducibility of the experimental results have advanced, more and more theorists have become attracted to focus on issues related to STM and SXM. The increasing effort in the development of theoretical concepts for STM/SXM has led to considerable improvements in understanding the contrast mechanism as well as the experimental conditions necessary to obtain reliable data. Therefore, this third volume on STM/SXM is not written by theorists for theorists, but rather for every scientist who is not satisfied by just obtaining real­ space images of surface structures by STM/SXM. After a brief introduction (Chap. 1), N. D. Lang first co...

  2. Preparation of Chemically Etched Tips for Ambient Instructional Scanning Tunneling Microscopy

    Science.gov (United States)

    Zaccardi, Margot J.; Winkelmann, Kurt; Olson, Joel A.

    2010-01-01

    A first-year laboratory experiment that utilizes concepts of electrochemical tip etching for scanning tunneling microscopy (STM) is described. This experiment can be used in conjunction with any STM experiment. Students electrochemically etch gold STM tips using a time-efficient method, which can then be used in an instructional grade STM that…

  3. Covalently Immobilised Cytochrome C Imaged by In Situ Scanning Tunnelling Microscopy

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Olesen, Klaus G.; Danilov, Alexey I.

    1997-01-01

    In situ scanning tunnelling microscopy (STM) imaging of cytochrome c (cyt c) on polycrystalline Pt surfaces and on Au(lll) was achieved first by covalent immobilisation of 3-aminopropyltriethoxysilane (3-APTS) brought to react with oxide present on the Pt surfaces. Covalently bound 3-APTS forms a...

  4. Scanning Tunneling Microscopy Studies of Topological Insulators Grown by Molecular Beam Epitaxy

    Directory of Open Access Journals (Sweden)

    Xue Qikun

    2012-03-01

    Full Text Available We summarize our recent scanning tunneling microscopy (STM study of topological insulator thin films grown by molecular beam epitaxy (MBE, which includes the observation of electron standing waves on topological insulator surface and the Landau quantization of topological surface states. The work has provided valuable information to the understanding of intriguing properties of topological insulators, as predicted by theory.

  5. Adsorption of Cu phthalocyanine on Pt modified Ge(001): A scanning tunneling microscopy study

    NARCIS (Netherlands)

    Saedi, A.; Berkelaar, Robin P.; Kumar, Avijit; Poelsema, Bene; Zandvliet, Henricus J.W.

    2010-01-01

    The adsorption configurations of copper phthalocyanine (CuPc) molecules on platinum-modified Ge(001) have been studied using scanning tunneling microscopy. After deposition at room temperature and cooling down to 77 K the CuPc molecules are still dynamic. However, after annealing at 550±50 K, the

  6. EDITORIAL: Three decades of scanning tunnelling microscopy that changed the course of surface science Three decades of scanning tunnelling microscopy that changed the course of surface science

    Science.gov (United States)

    Ramachandra Rao, M. S.; Margaritondo, Giorgio

    2011-11-01

    Three decades ago, with a tiny tip of platinum, the scientific world saw the real space imaging of single atoms with unprecedented spatial resolution. This signalled the birth of one of the most versatile surface probes, based on the physics of quantum mechanical tunnelling: the scanning tunnelling microscope (STM). Invented in 1981 by Gerd Binnig and Heinrich Rohrer of IBM, Zurich, it led to their award of the 1986 Nobel Prize. Atoms, once speculated to be abstract entities used by theoreticians for mere calculations, can be seen to exist for real with the nano-eye of an STM tip that also gives real-space images of molecules and adsorbed complexes on surfaces. From a very fundamental perspective, the STM changed the course of surface science and engineering. STM also emerged as a powerful tool to study various fundamental phenomena relevant to the properties of surfaces in technological applications such as tribology, medical implants, catalysis, sensors and biology—besides elucidating the importance of local bonding geometries and defects, non-periodic structures and the co-existence of nano-scale phases. Atom-level probing, once considered a dream, has seen the light with the evolution of STM. An important off-shoot of STM was the atomic force microscope (AFM) for surface mapping of insulating samples. Then followed the development of a flurry of techniques under the general name of scanning probe microscopy (SPM). These techniques (STM, AFM, MFM, PFM etc) designed for atomic-scale-resolution imaging and spectroscopy, have led to brand new developments in surface analysis. All of these novel methods enabled researchers in recent years to image and analyse complex surfaces on microscopic and nanoscopic scales. All of them utilize a small probe for sensing the surface. The invention of AFM by Gerd Binnig, Calvin Quate and Christopher Gerber opened up new opportunities for characterization of a variety of materials, and various industrial applications could be

  7. Dopant migration in silicon during implantation/annealing measured by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hessel, H.E.; Memmert, U.; Behm, R.J. (Univ. Muenchen (West Germany)); Cerva, H. (Siemens Research Lab., Muenchen (West Germany))

    In this paper spatial correlation between the lateral distribution of the doping type and the former implantation mask edge was investigated by scanning tunneling microscopy (STM) measurements. The position of the former mask edge was determined from surface steps resolved by STM topography measurements. Current imaging tunneling spectroscopy (CITS) data recorded simultaneously allowed to detect the transition from a high doping level with an ohmic I-V curve to a lower doping level displaying a Schottky barrier behavior. The influence of different annealing treatments on the position of this transition was investigated.

  8. Pulse Plating on Gold Surfaces Studied by In Situ Scanning Tunneling Microscopy

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Bech-Nielsen, Gregers; Møller, Per

    1994-01-01

    Deposition of bulk copper on thin film gold surfaces is carried out by computer-aided pulse plating. It is demonstrated that the morphology of the copper deposit can be studied by in situ scanning tunnelling microscopy both in potentiostatic experiments and in galvanostatic experiments. Optimized...... procedures for obtaining smooth deposits by pulse plating are explained in terms of a levelling effect. Possible non-faradaic processes observed in measurements with high frequency pulse plating are discussed....

  9. Simultaneous scanning tunneling microscopy and synchrotron X-ray measurements in a gas environment.

    Science.gov (United States)

    Mom, Rik V; Onderwaater, Willem G; Rost, Marcel J; Jankowski, Maciej; Wenzel, Sabine; Jacobse, Leon; Alkemade, Paul F A; Vandalon, Vincent; van Spronsen, Matthijs A; van Weeren, Matthijs; Crama, Bert; van der Tuijn, Peter; Felici, Roberto; Kessels, Wilhelmus M M; Carlà, Francesco; Frenken, Joost W M; Groot, Irene M N

    2017-11-01

    A combined X-ray and scanning tunneling microscopy (STM) instrument is presented that enables the local detection of X-ray absorption on surfaces in a gas environment. To suppress the collection of ion currents generated in the gas phase, coaxially shielded STM tips were used. The conductive outer shield of the coaxial tips can be biased to deflect ions away from the tip core. When tunneling, the X-ray-induced current is separated from the regular, 'topographic' tunneling current using a novel high-speed separation scheme. We demonstrate the capabilities of the instrument by measuring the local X-ray-induced current on Au(1 1 1) in 800 mbar Ar. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Scanning tunneling microscopy investigation of different porphynoids on a Ni-prestructured Cu(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Roeckert, Michael; Buchner, Florian; Zillner, Elisabeth; Glaessel, Stefanie; Steinrueck, Hans-Peter; Marbach, Hubertus [Lehrstuhl fuer Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Universitaet Erlangen-Nuernberg, Egerlandstrasse 3, D-91058 Erlangen (Germany)

    2010-07-01

    The assembly of organic molecules on single-crystal surfaces is an approach towards the creation of novel materials with outstanding properties. Porphyrins appear to be ideal candidates to generate functional molecular devices, due to their self-assembly properties and their versatile functionality. In the present work we study the possibility to locally anchor or functionalize porphyrins on a prestructured surface, namely a composite Ni/Cu(111) surface, by scanning tunneling microscopy (STM) in ultra-high vacuum at room temperature. Based on scanning tunneling micrographs and movies the dynamics, assembly and intramolecular conformation of the corresponding porphyrins (2HTPP,CoTPP,OEP) as well as the role of molecule-molecule and molecule-substrate interactions are discussed. The obtained findings indeed indicate the possibility to locally anchor and/or functionalize (e.g. metalate) the porphyrins on a Cu(111) surface prestructured either with atomically flat Ni- or oxygen-islands.

  11. Plasmons and Electrons as Nanosecond-Fast Sensors for Scanning Tunneling Microscopy

    Science.gov (United States)

    Loth, Sebastian

    2014-03-01

    The ability to measure the fast dynamical evolution of atomic-scale systems often holds the key to their understanding. We combine fast pump-probe spectroscopy tools with low-temperature scanning tunneling microscopy to study atomically assembled arrays of magnetic atoms. The dynamical information quantifies spin lifetimes, magnetic stability and even allows identifying the cross-over between quantum spins and classical magnetism. The spin relaxation times of transition metal atoms can be measured by all-electronic pump probe spectroscopy in which nanosecond-fast voltage pulses excite the spins and probe the average time-dependent response by variations in the spin-polarized tunnel current. In addition, the fast evolution of the local electrostatic potential can be mapped by detecting plasmonic light emission from the STM tunnel junction with time correlating single photon counting. The combination of electrical stimulus and optical detection provides precise control of the excitation process of individual atoms enabling new experiments to probe charge and spin dynamics in the scanning tunneling microscope.

  12. Submonolayer growth of Pd on Cu(111) studied by scanning tunneling microscopy

    DEFF Research Database (Denmark)

    Lægsgaard, E.; Ruban, Andrei; Stensgaard, I.

    1998-01-01

    The growth mode of sub-monolayer amounts of Pd on Cu(111) in the temperature range - 80-300 degrees C has been investigated by scanning tunneling microscopy (STM), Rutherford backscattering spectroscopy (RBS) and Auger electron spectroscopy (AES). Below approximate to 100 degrees C, the Pd induced...... is dug out from the surface in extended, monolayer deep pits, and concurrently, the brims and islands increase in height by one layer. High-resolution STM images of brims and islands in this phase are interpreted as evidence for Cu capping. For Pd evaporation at temperatures of 220-300 degrees C...

  13. Structure and Reactions of Carbon and Hydrogen on Ru(0001): A Scanning Tunneling Microscopy Study

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Tomoko K.; Mugarza, Aitor; Cerda, Jorge; Salmeron, Miquel

    2008-09-09

    The interaction between carbon and hydrogen atoms on a Ru(0001) surface was studied using scanning tunneling microscopy (STM), Density Functional Theory (DFT) and STM image calculations. Formation of CH species by reaction between adsorbed H and C was observed to occur readily at 100 K. When the coverage of H increased new complexes of the form CH+nH (n = 1, 2 and 3) were observed. These complexes, never observed before, might be precursors for further hydrogenation reactions. DFT analysis reveals that a considerable energy barrier exists for the CH+H {yields} CH{sub 2} reaction.

  14. Cytochrome C Dynamics at Gold and Glassy Carbon Surfaces Monitored by in Situ Scanning Tunnel Microscopy

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Møller, Per; Pedersen, Marianne Vind

    1995-01-01

    We have investigated the absorption of cytochrome c on gold and glassy carbon substrates by in situ scanning tunnel microscopy under potentiostatic control of both substrate and tip. Low ionic strength and potential ranges where no Faradaic current flows were used. Cyt c aggregates into flat...... composite structures of about 50 nm lateral extension at gold surfaces. The aggregates evolve in time, and structures resembling individual cyt c molecules can be distinguished in the space between the 50 nm structures. Cyt c aggregates also form at glassy carbon but have a different, unbroken character...

  15. Atomic-scale structure of dislocations revealed by scanning tunneling microscopy and molecular dynamics

    DEFF Research Database (Denmark)

    Christiansen, Jesper; Morgenstern, K.; Schiøtz, Jakob

    2002-01-01

    The intersection between dislocations and a Ag(111) surface has been studied using an interplay of scanning tunneling microscopy (STM) and molecular dynamics. Whereas the STM provides atomically resolved information about the surface structure and Burgers vectors of the dislocations......, the simulations can be used to determine dislocation structure and orientation in the near-surface region. In a similar way, the subsurface structure of other extended defects can be studied. The simulations show dislocations to reorient the partials in the surface region leading to an increased splitting width...

  16. Creating Nanoscale Pits on Solid Surfaces in Aqueous Environment with Scanning Tunnelling Microscopy

    DEFF Research Database (Denmark)

    Chi, Qijin; Zhang, Jingdong; Friis, Esben P.

    2000-01-01

    A novel method has been developed to fabricate nanoscale pits on Au(111) in aqueous environments by in situ scanning tunnelling microscopy (STM), based on critical interactions between tip and substrate. The most striking advantages of the present method are that the dimension and position...... of the pits can be controlled well in aqueous environments, and the operations are simple. Parameters affecting the pit formation and size have been systematically characterized to show that pit formation is dominated by bias voltage. A mechanism is proposed based on local surface reconstruction induced...

  17. Identification of nitrogen dopants in single-walled carbon nanotubes by scanning tunneling microscopy.

    Science.gov (United States)

    Tison, Yann; Lin, Hong; Lagoute, Jérôme; Repain, Vincent; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Henrard, Luc; Zheng, Bing; Susi, Toma; Kauppinen, Esko I; Ducastelle, François; Loiseau, Annick

    2013-08-27

    Using scanning tunnelling microscopy and spectroscopy, we investigated the atomic and electronic structure of nitrogen-doped single walled carbon nanotubes synthesized by chemical vapor deposition. The insertion of nitrogen in the carbon lattice induces several types of point defects involving different atomic configurations. Spectroscopic measurements on semiconducting nanotubes reveal that these local structures can induce either extended shallow levels or more localized deep levels. In a metallic tube, a single doping site associated with a donor state was observed in the gap at an energy close to that of the first van Hove singularity. Density functional theory calculations reveal that this feature corresponds to a substitutional nitrogen atom in the carbon network.

  18. First-principles modelling of scanning tunneling microscopy using non-equilibrium Green's functions

    DEFF Research Database (Denmark)

    Lin, H.P.; Rauba, J.M.C.; Thygesen, Kristian Sommer

    2010-01-01

    The investigation of electron transport processes in nano-scale architectures plays a crucial role in the development of surface chemistry and nano-technology. Experimentally, an important driving force within this research area has been the concurrent refinements of scanning tunneling microscopy...... into account. As an illustrating example we apply the NEGF-STM method to the Si(001)(2x1):H surface with sub-surface P doping and discuss the results in comparison to the Bardeen and Tersoff-Hamann methods....

  19. Doppler-scanning tunneling microscopy current imaging in superconductor-ferromagnet hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Moore, S. A.; Plummer, G.; Fedor, J.; Pearson, J. E.; Novosad, V.; Karapetrov, G.; Iavarone, M.

    2016-01-25

    Mapping the distribution of currents inside a superconductor is usually performed indirectly through imaging of the stray magnetic fields above the surface. Here, we show that by direct imaging of the Doppler shift contribution to the quasiparticle excitation spectrum in the superconductor using low temperature scanning tunneling microscopy, we obtain directly the distribution of supercurrents inside the superconductor. We demonstrate the technique at the example of superconductor/ferromagnet hybrid structure that produces intricate current pattern consisting of combination Meissner shielding currents and Abrikosov vortex currents.

  20. Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Govind Mallick

    2017-08-01

    Full Text Available Due to their unique chemical, thermal, electronic and photonic properties, low -dimensional transition metal oxides, especially NiO, have attracted great deal of attention for potential applications in a wide range of technologies, such as, sensors, electrochromic coatings and self-healing materials. However, their synthesis involves multi-step complex procedures that in addition to being expensive, further introduce impurities. Here we present a low cost facile approach to synthesize uniform size NiO nanoparticles (NPs from hydrothermally grown Ni(OH2. Detailed transmission electron microscopic analysis reveal the average size of NiO NPs to be around 29 nm. The dimension of NiO NP is also corroborated by the small area scanning tunneling microscope (STM measurements. Further, we investigate electron transport characteristics of newly synthesized Ni(OH2 and NiO nanoparticles on p-type Si substrate using scanning tunneling microscopy. The conductivity of Ni(OH2 and NiO are determined to be 1.46x10-3 S/cm and 2.37x10-5 S/cm, respectively. The NiO NPs exhibit a lower voltage window (∼0.7 V electron tunneling than the parent Ni(OH2.

  1. Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

    Science.gov (United States)

    Mallick, Govind; Labh, Jyotsna; Giri, Lily; Pandey, Avinash C.; Karna, Shashi P.

    2017-08-01

    Due to their unique chemical, thermal, electronic and photonic properties, low -dimensional transition metal oxides, especially NiO, have attracted great deal of attention for potential applications in a wide range of technologies, such as, sensors, electrochromic coatings and self-healing materials. However, their synthesis involves multi-step complex procedures that in addition to being expensive, further introduce impurities. Here we present a low cost facile approach to synthesize uniform size NiO nanoparticles (NPs) from hydrothermally grown Ni(OH)2. Detailed transmission electron microscopic analysis reveal the average size of NiO NPs to be around 29 nm. The dimension of NiO NP is also corroborated by the small area scanning tunneling microscope (STM) measurements. Further, we investigate electron transport characteristics of newly synthesized Ni(OH)2 and NiO nanoparticles on p-type Si substrate using scanning tunneling microscopy. The conductivity of Ni(OH)2 and NiO are determined to be 1.46x10-3 S/cm and 2.37x10-5 S/cm, respectively. The NiO NPs exhibit a lower voltage window (˜0.7 V) electron tunneling than the parent Ni(OH)2.

  2. Bulk crystalline copper electrodeposition on polycrystalline gold surfaces observed by in-situ scanning tunneling microscopy

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Bech-Nielsen, Gregers; Møller, Per

    1994-01-01

    Bulk copper electrodeposition onto technical gold surfaces in electrolytes of 0.05 M H2SO4 and 1 mM CuSO4 was investigated by in-situ scanning tunnelling microscopy at fixed overpotentials. At potentials between -60 and -30 mV the growth of bulk copper proceeds in cycles of nucleation, agglomerat......Bulk copper electrodeposition onto technical gold surfaces in electrolytes of 0.05 M H2SO4 and 1 mM CuSO4 was investigated by in-situ scanning tunnelling microscopy at fixed overpotentials. At potentials between -60 and -30 mV the growth of bulk copper proceeds in cycles of nucleation......, agglomeration and crystallization. Crystalline copper is seen as involving an intermediate stage in the progress of growth. The final stage in the growth involves an equilibrium of copper electrochemically dissolving and precipitating. The drift velocity was measured for a gold surface subjected to flame...... annealing and subsequently installed in the cell compartment. It was found that the drift velocity decays with time in an exponential-like manner, and a 70 min waiting time before experiments with atomic resolution is recommended. Atomic resolution on Au(111) has been obtained, and an apparent surface...

  3. Atomic species identification at the (101) anatase surface by simultaneous scanning tunnelling and atomic force microscopy

    Science.gov (United States)

    Stetsovych, Oleksandr; Todorović, Milica; Shimizu, Tomoko K.; Moreno, César; Ryan, James William; León, Carmen Pérez; Sagisaka, Keisuke; Palomares, Emilio; Matolín, Vladimír; Fujita, Daisuke; Perez, Ruben; Custance, Oscar

    2015-01-01

    Anatase is a pivotal material in devices for energy-harvesting applications and catalysis. Methods for the accurate characterization of this reducible oxide at the atomic scale are critical in the exploration of outstanding properties for technological developments. Here we combine atomic force microscopy (AFM) and scanning tunnelling microscopy (STM), supported by first-principles calculations, for the simultaneous imaging and unambiguous identification of atomic species at the (101) anatase surface. We demonstrate that dynamic AFM-STM operation allows atomic resolution imaging within the material's band gap. Based on key distinguishing features extracted from calculations and experiments, we identify candidates for the most common surface defects. Our results pave the way for the understanding of surface processes, like adsorption of metal dopants and photoactive molecules, that are fundamental for the catalytic and photovoltaic applications of anatase, and demonstrate the potential of dynamic AFM-STM for the characterization of wide band gap materials. PMID:26118408

  4. Scanning tunneling microscopy and spectroscopy of iron suicide epitaxially grown on Si(111)

    Science.gov (United States)

    Raunau, Werner; Niehus, Horst; Schilling, Thomas; Comsa, George

    1993-05-01

    Epitaxial iron suicide films have been grown on Si(111) by solid phase epitaxy (SPE) in UHV. Structural and electronic properties have been investigated with scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). For initial Fe deposition up to 3 Å and annealing at 850 K, metallic γ-FeSi 2 is formed. These films exhibit a perfect (2 × 2) superstructure, which is attributed to γ-FeSi 2(111) with Si termination. SPE at higher initial iron deposition (15 Å) and annealing at 800 K results in ɛ-FeSi showing a (√3 × √3) R30° superstructure. Subsequent annealing above 900 K leads to β-FeSi 2 formation. As by STS, β-FeSi 2 films are semiconducting with Eg = 0.85 eV. STM topographs show that SPE produces rough silicide surfaces wit β-FeSi 2(101) [and not β-FeSi 2(110)] epitaxy. The atomic structure on β-FeSi 2 terraces is complex, consisting domain boundaries and defects.

  5. Scanning tunneling microscopy studies of organic monolayers adsorbed on the rhodium(111) crystal surface

    Energy Technology Data Exchange (ETDEWEB)

    Cernota, Paul Davis [Univ. of California, Berkeley, CA (United States)

    1999-08-01

    Scanning Tunneling Microscopy studies were carried out on ordered overlayers on the (111) surface of rhodium. These adsorbates include carbon monoxide (CO), cyclohexane, cyclohexene, 1,4-cyclohexadiene, para-xylene, and meta-xylene. Coadsorbate systems included: CO with ethylidyne, CO with para- and meta-xylene, and para-xylene with meta-xylene. In the case of CO, the structure of the low coverage (2x2) overlayer has been observed. The symmetry of the unit cell in this layer suggests that the CO is adsorbed in the 3-fold hollow sites. There were also two higher coverage surface structures with (√7x√7) unit cells. One of these is composed of trimers of CO and has three CO molecules in each unit cell. The other structure has an additional CO molecule, making a total of four. This extra CO sits on a top site.

  6. Hydrogen adsorption on Ru(001) studied by Scanning TunnelingMicroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tatarkhanov, Mous; Rose, Franck; Fomin, Evgeny; Ogletree, D.Frank; Salmeron, Miquel

    2008-01-18

    The adsorption of hydrogen on Ru(001) was studied by scanning tunneling microscopy at temperatures around 50 K. Hydrogen was found to adsorb dissociatively forming different ordered structures as a function of coverage. In order of increasing coverage {theta} in monolayers (ML) these were ({radical}3 x {radical}3)r30{sup o} at {theta} = 0.3 ML; (2 x 1) at {theta} = 0.50 ML, (2 x 2)-3H at {theta} = 0.75, and (1 x 1) at {theta} = 1.00. Some of these structures were observed to coexist at intermediate coverage values. Close to saturation of 1 ML, H-vacancies (unoccupied three fold fcc hollow Ru sites) were observed either as single entities or forming transient aggregations. These vacancies diffuse and aggregate to form active sites for the dissociative adsorption of hydrogen.

  7. Interfacial self-assembly of amino acids and peptides: Scanning tunneling microscopy investigation

    Science.gov (United States)

    Xu, Li-Ping; Liu, Yibiao; Zhang, Xueji

    2011-12-01

    Proteins play important roles in human daily life. To take advantage of the lessons learned from nature, it is essential to investigate the self-assembly of subunits of proteins, i.e., amino acids and polypeptides. Due to its high resolution and versatility of working environment, scanning tunneling microscopy (STM) has become a powerful tool for studying interfacial molecular assembly structures. This review is intended to reflect the progress in studying interfacial self-assembly of amino acids and peptides by STM. In particular, we focus on environment-induced polymorphism, chiral recognition, and coadsorption behavior with molecular templates. These studies would be highly beneficial to research endeavors exploring the mechanism and nanoscale-controlling molecular assemblies of amino acids and polypeptides on surfaces, understanding the origin of life, unravelling the essence of disease at the molecular level and deeming what is necessary for the ``bottom-up'' nanofabrication of molecular devices and biosensors being constructed with useful properties and desired performance.

  8. Ultra-High Vacuum Compatible Optical Chopper System for Synchrotron X-ray Scanning Tunneling Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hao; Cummings, Marvin L.; Shirato, Nozomi; Stripe, Benjamin D.; Rosenmann, Daniel; Preissner, Curt A.; Freeland, John W.; Kersell, Heath R.; Hla, Saw Wai; Rose, Volker

    2015-01-01

    High-speed beam choppers are a crucial part of time-resolved x-ray studies as well as a necessary component to enable elemental contrast in synchrotron x-ray scanning tunneling microscopy (SX-STM). However, many chopper systems are not capable of operation in vacuum, which restricts their application to x-ray studies with high photon energies, where air absorption does not present a significant problem. To overcome this limitation, we present a fully ultra-high vacuum (UHV) compatible chopper system capable of operating at variable chopping frequencies up to 4 kHz. The lightweight aluminum chopper disk is coated with Ti and Au films to provide the required beam attenuation for soft and hard x-rays with photon energies up to about 12 keV. The chopper is used for lock-in detection of x-ray enhanced signals in SX-STM.

  9. Ultra-high vacuum compatible optical chopper system for synchrotron x-ray scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hao, E-mail: hc000211@ohio.edu [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Nanoscale and Quantum Phenomena Institute, Physics & Astronomy Department, Ohio University, Athens, Ohio 45701 (United States); Cummings, Marvin; Shirato, Nozomi; Stripe, Benjamin; Preissner, Curt; Freeland, John W. [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Rosenmann, Daniel [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Kersell, Heath; Hla, Saw-Wai [Nanoscale and Quantum Phenomena Institute, Physics & Astronomy Department, Ohio University, Athens, Ohio 45701 (United States); Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Rose, Volker, E-mail: vrose@anl.gov [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

    2016-01-28

    High-speed beam choppers are a crucial part of time-resolved x-ray studies as well as a necessary component to enable elemental contrast in synchrotron x-ray scanning tunneling microscopy (SX-STM). However, many chopper systems are not capable of operation in vacuum, which restricts their application to x-ray studies with high photon energies, where air absorption does not present a significant problem. To overcome this limitation, we present a fully ultra-high vacuum (UHV) compatible chopper system capable of operating at variable chopping frequencies up to 4 kHz. The lightweight aluminum chopper disk is coated with Ti and Au films to provide the required beam attenuation for soft and hard x-rays with photon energies up to about 12 keV. The chopper is used for lock-in detection of x-ray enhanced signals in SX-STM.

  10. Atomic resolution on the (111 )B surface of mercury cadmium telluride by scanning tunneling microscopy

    Science.gov (United States)

    Zha, Fang-Xing; Hong, Feng; Pan, Bi-Cai; Wang, Yin; Shao, Jun; Shen, Xue-Chu

    2018-01-01

    The real-space atomic surface structure of mercury cadmium telluride was successfully achieved on the (111 )B surface of H g0.78C d0.22Te by ultrahigh-vacuum scanning tunneling microscopy (STM). The work casts light on the reconstructions of the (111 )B surface unraveling a (2 ×2 ) surface reconstruction induced by adatom adsorption of Cd. The other (2 ×2 ) surface reconstruction is clarified to be induced by the single Te vacancy, which is more stable than the reconstruction of multivacancies in contrast to the prevailing view. The simulated STM images are in good agreement with the experiments. We also observed an in situ morphology transition from the (1 ×1 ) structure to those (2 ×2 ) reconstructions, implying the stability of the reconstructions.

  11. High-Resolution Scanning Tunneling Microscopy Studies of Molecular Nanostructures on Surfaces

    DEFF Research Database (Denmark)

    Song, Xin

    . First, to study the role of hydrogen bonding in self-assembly, we investigate the monomolecular self-assembled system of pyrene-4,5,9,10-tetrone and phenanthrene- 9,10-dione molecules on Au(111) and HOPG surface respectively and the binary molecular self-assembled system of stearic acid and guanine...... molecules co-adsorbed on HOPG surface. Hydrogen bonding plays a key role in these self-assembled nanostructures and the substrate could also give an effect in the self-assembly. Second, to study the self-assembly across the terrace steps as a defect on surface, the chiral self-assembled supramolecular...... of nanostructures requires deeper insight into the adsorption sites, adsorption configurations, diffusion behaviour and driving forces for self-assembly of different molecules or atoms on different substrates. To study these fundamental issues, scanning tunneling microscopy (STM) has proven to be an ideal choice...

  12. Scanning tunneling microscopy on the formation of lipoamide-cyclodextrin monolayer on Au(111)

    Science.gov (United States)

    Yasuda, Satoshi; Shigekawa, Hidemi; Suzuki, Iwao; Nakamura, Tohru; Matsumoto, Mutsuyoshi; Komiyama, Makoto

    2000-01-01

    β-cyclodextrin molecules modified with lipoamide residue (LP-β-CyD) were self-assembled on an Au(111) surface in ethanol solution, and the growth process was studied by scanning tunneling microscopy. At the initial stage, adsorption sites were not only random, but also partially linear ordering, which suggests the existence of some influence by the herringbone structure of the Au(111) surface. According to the macroscopic analysis, the subsequent growth process was explained by the Elovich model, which is based on the repulsive interaction between adsorbed molecules. However, when the immersion time increased, island structures began forming. This result suggests the interaction between LP-β-CyD molecules as attractive, which in fact is more probable in consideration of the possibility of the hydrophobic and the hydrogen bonding interactions between CyD molecules. Finally, formation of a single LP-β-CyD layer was clearly confirmed.

  13. Scanning tunneling microscopy I general principles and applications to clean and absorbate-covered surfaces

    CERN Document Server

    Wiesendanger, Roland

    1994-01-01

    Since the first edition of "Scanning 'funneling Microscopy I" has been pub­ lished, considerable progress has been made in the application of STM to the various classes of materials treated in this volume, most notably in the field of adsorbates and molecular systems. An update of the most recent develop­ ments will be given in an additional Chapter 9. The editors would like to thank all the contributors who have supplied up­ dating material, and those who have provided us with suggestions for further improvements. We also thank Springer-Verlag for the decision to publish this second edition in paperback, thereby making this book affordable for an even wider circle of readers. Hamburg, July 1994 R. Wiesendanger Preface to the First Edition Since its invention in 1981 by G. Binnig, H. Rohrer and coworkers at the IBM Zurich Research Laboratory, scanning tunneling microscopy (STM) has devel­ oped into an invaluable surface analytical technique allowing the investigation of real-space surface structures at th...

  14. A scanning tunneling microscopy based potentiometry technique and its application to the local sensing of the spin Hall effect

    OpenAIRE

    Ting Xie; Michael Dreyer; David Bowen; Dan Hinkel; R. E. Butera; Charles Krafft; Isaak Mayergoyz

    2017-01-01

    A scanning tunneling microscopy based potentiometry technique for the measurements of the local surface electric potential is presented. A voltage compensation circuit based on this potentiometry technique is developed and employed to maintain a desired tunneling voltage independent of the bias current flow through the film. The application of this potentiometry technique to the local sensing of the spin Hall effect is outlined and some experimental results are reported.

  15. A scanning tunneling microscopy based potentiometry technique and its application to the local sensing of the spin Hall effect

    Science.gov (United States)

    Xie, Ting; Dreyer, Michael; Bowen, David; Hinkel, Dan; Butera, R. E.; Krafft, Charles; Mayergoyz, Isaak

    2017-12-01

    A scanning tunneling microscopy based potentiometry technique for the measurements of the local surface electric potential is presented. A voltage compensation circuit based on this potentiometry technique is developed and employed to maintain a desired tunneling voltage independent of the bias current flow through the film. The application of this potentiometry technique to the local sensing of the spin Hall effect is outlined and some experimental results are reported.

  16. Atomic structure of screw dislocations intersecting the Au(111) surface: A combined scanning tunneling microscopy and molecular dynamics study

    DEFF Research Database (Denmark)

    Engbæk, Jakob; Schiøtz, Jakob; Dahl-Madsen, Bjarke

    2006-01-01

    The atomic-scale structure of naturally occurring screw dislocations intersecting a Au(111) surface has been investigated both experimentally by scanning tunneling microscopy (STM) and theoretically using molecular dynamics (MD) simulations. The step profiles of 166 dislocations were measured using...

  17. INTER-LAYER INTERACTION IN DOUBLE-WALLED CARBON NANOTUBES EVIDENCED BY SCANNING TUNNELING MICROSCOPY AND SPECTROSCOPY

    DEFF Research Database (Denmark)

    Giusca, Cristina E; Tison, Yann; Silva, S. Ravi P.

    2008-01-01

    Scanning Tunneling Microscopy and Spectroscopy have been used in an attempt to elucidate the electronic structure of nanotube systems containing two constituent shells. Evidence for modified electronic structure due to the inter-layer interaction in double-walled carbon nanotubes is provided by t...

  18. Adsorption of human insulin on single-crystal gold surfaces investigated by in situ scanning tunnelling microscopy and electrochemistry

    DEFF Research Database (Denmark)

    Welinder, Anna Christina; Zhang, Jingdong; Steensgaard, D.B.

    2010-01-01

    We have explored the adsorption of zinc-free human insulin on the three low-index single-crystalline Au(111)-, Au(100)- and Au(110)-surfaces in aqueous buffer (KH2PO4, pH 5) by a combination of electrochemical scanning tunnelling microscopy (in situ STM) at single-molecule resolution and linear s...

  19. Preparation of scanning tunneling microscopy tips using pulsed alternating current etching

    Energy Technology Data Exchange (ETDEWEB)

    Valencia, Victor A.; Thaker, Avesh A.; Derouin, Jonathan; Valencia, Damian N.; Farber, Rachael G.; Gebel, Dana A.; Killelea, Daniel R., E-mail: dkillelea@luc.edu [Department of Chemistry and Biochemistry, Loyola University Chicago, 1068 W. Sheridan Rd., Chicago, Illinois 60660 (United States)

    2015-03-15

    An electrochemical method using pulsed alternating current etching (PACE) to produce atomically sharp scanning tunneling microscopy (STM) tips is presented. An Arduino Uno microcontroller was used to control the number and duration of the alternating current (AC) pulses, allowing for ready optimization of the procedures for both Pt:Ir and W tips using a single apparatus. W tips prepared using constant and pulsed AC power were compared. Tips fashioned using PACE were sharper than those etched with continuous AC power alone. Pt:Ir tips were prepared with an initial coarse etching stage using continuous AC power followed by fine etching using PACE. The number and potential of the finishing AC pulses was varied and scanning electron microscope imaging was used to compare the results. Finally, tip quality using the optimized procedures was verified by UHV-STM imaging. With PACE, at least 70% of the W tips and 80% of the Pt:Ir tips were of sufficiently high quality to obtain atomically resolved images of HOPG or Ni(111)

  20. An easy-to-implement filter for separating photo-excited signals from topography in scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang Kangkang; Rosenmann, Daniel; Holt, Martin; Winarski, Robert; Hla, Saw-Wai [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Rose, Volker [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

    2013-06-15

    In order to achieve elemental and chemical sensitivity in scanning tunneling microscopy (STM), synchrotron x-rays have been applied to excite core-level electrons during tunneling. The x-ray photo-excitations result in tip currents that are superimposed onto conventional tunneling currents. While carrying important physical information, the varying x-ray induced currents can destabilize the feedback loop causing it to be unable to maintain a constant tunneling current, sometimes even causing the tip to retract fully or crash. In this paper, we report on an easy-to-implement filter circuit that can separate the x-ray induced currents from conventional tunneling currents, thereby allowing simultaneous measurements of topography and chemical contrasts. The filter and the schematic presented here can also be applied to other variants of light-assisted STM such as laser STM.

  1. Electronic structure of carbon nanotube systems measured with scanning tunneling microscopy

    Science.gov (United States)

    Hornbaker, Daniel Jay

    Carbon fullerenes are unusually structured molecules with robust mechanical and electronic properties. Their versatility is astounding; envisioned applications range from field emission displays to impregnated metal composites, battery storage media, and nanoelectronic devices. The combination of simple constituency, diverse behavior, and ease of fabrication makes these materials a cornerstone topic in current research. This thesis details scanning tunneling microscopy (STM) experiments investigating how carbon nanotube fullerenes interact with and couple to their local environment. Scanning tunneling microscopy continues to be a key method for characterizing fullerenes, particularly in regards to their electronic properties. The atomic scale nature of this technique makes it uniquely suited for observing individual molecules and determining correlations between locally measured electronic properties and the particular environment of the molecule. The primary subject of this study is single-wall carbon nanotubes (SWNTs), which were observed under various perturbative influences resulting in measurable changes in the electronic structure. Additionally, fullerene heterostructures formed by the encapsulation of C60 molecules within the hollow interiors of SWNTs were characterized for the first time with STM. These novel macromolecules (dubbed "peapods") demonstrate the potential for custom engineering the properties of fullerene materials. Measurements indicate that the properties of individual nanotubes depend sensitively on local interactions. In particular, pronounced changes in electronic behavior are observed in nanotubes exhibiting mechanical distortion, interacting with extrinsic materials (including other nanotubes), and possessing intrinsic defects in the atomic lattice. In fullerene peapods, while no discernable change in the atomic ordering of the encapsulating nanotubes was evident, the presence of interior C60 molecules has a dramatic effect on the

  2. Imaging by in situ Scanning Tunnelling Microscopy and its Nanotechnological Perspectives

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    2002-01-01

    in the interpretation of the imaging procedure. Other methods of in situ Scanning Probe Microscopy (in situ SPM), such as in situ Scanning Force Microscopy (in situ AFM) are considered for the sake of comparison and they are applied to imaging of non-conducting systems. Major results include demonstration of atomic...

  3. Visualizing the interface state of PTCDA on Au(111) by scanning tunneling microscopy

    Science.gov (United States)

    Nicoara, N.; Méndez, J.; Gómez-Rodríguez, J. M.

    2016-11-01

    We have investigated by means of scanning tunneling microscopy (STM) and spectroscopy (STS) the electronic structure of PTCDA (3,4,9,10-perylene-tetracarboxylic-dianhydride) molecular monolayers grown on Au(111). Thanks to our STM/STS measurements, performed under ultra-high vacuum conditions and low temperature, an interface state directly derived from the Shockley-type surface state of pristine Au(111) has been detected. Low bias voltage STM images show the formation of standing wave patterns both on Au(111) and on Au(111) covered by a PTCDA monolayer. These patterns result from the scattering of quasi-free 2D electron surface states with surface defects. By Fourier transforming STM images, the corresponding wavevectors have been extracted. In particular, the simultaneous imaging of both pristine and PTCDA covered Au(111) areas has allowed to measure the Fermi contours and the Fermi wavevectors of both systems. These measurements show that one monolayer PTCDA on Au(111) presents an interface state with an isotropic circular Fermi contour and smaller Fermi wavector ({k}{{F}}=0.15+/- 0.01\\phantom{\\rule{thinmathspace}{0ex}}\\mathring{{{A}}}{}-1) than the corresponding Fermi wavector of pristine Au(111) ({k}{{F}}=0.17+/- 0.01\\phantom{\\rule{thinmathspace}{0ex}}\\mathring{{{A}}}{}-1). This picture is consistent with an upward shift of the Shockley-type surface state due to the presence of the molecular monolayer.

  4. Unveiling Stability Criteria of DNA-Carbon Nanotubes Constructs by Scanning Tunneling Microscopy and Computational Modeling

    Directory of Open Access Journals (Sweden)

    Svetlana Kilina

    2011-01-01

    Full Text Available We present a combined approach that relies on computational simulations and scanning tunneling microscopy (STM measurements to reveal morphological properties and stability criteria of carbon nanotube-DNA (CNT-DNA constructs. Application of STM allows direct observation of very stable CNT-DNA hybrid structures with the well-defined DNA wrapping angle of 63.4° and a coiling period of 3.3 nm. Using force field simulations, we determine how the DNA-CNT binding energy depends on the sequence and binding geometry of a single strand DNA. This dependence allows us to quantitatively characterize the stability of a hybrid structure with an optimal π-stacking between DNA nucleotides and the tube surface and better interpret STM data. Our simulations clearly demonstrate the existence of a very stable DNA binding geometry for (6,5 CNT as evidenced by the presence of a well-defined minimum in the binding energy as a function of an angle between DNA strand and the nanotube chiral vector. This novel approach demonstrates the feasibility of CNT-DNA geometry studies with subnanometer resolution and paves the way towards complete characterization of the structural and electronic properties of drug-delivering systems based on DNA-CNT hybrids as a function of DNA sequence and a nanotube chirality.

  5. Copper intercalation at the interface of graphene and Ir(111) studied by scanning tunneling microscopy

    Science.gov (United States)

    Sicot, M.; Fagot-Revurat, Y.; Kierren, B.; Vasseur, G.; Malterre, D.

    2014-11-01

    We report on the intercalation of a submonolayer of copper at 775 K underneath graphene epitaxially grown on Ir(111) studied by means of low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) at 77 K. Nucleation and growth dynamics of Cu below graphene have been investigated, and, most importantly, the intercalation mechanism has been identified. First, LEED patterns reveal the pseudomorphic growth of Cu on Ir under the topmost graphene layer resulting in a large Cu in-plane lattice parameter expansion of about 6% compared to Cu(111). Second, large-scale STM topographs as a function of Cu coverage show that Cu diffusion on Ir below graphene exhibits a low energy barrier resulting in Cu accumulation at Ir step edges. As a result, the graphene sheet undergoes a strong edges reshaping. Finally, atomically-resolved STM images reveal a damaged graphene sheet at the atomic scale after metal intercalation. Point defects in graphene were shown to be carbon vacancies. According to these results, a Cu penetration path beneath graphene is proposed to occur via metal aided defect formation with no or poor self healing of the graphene sheet. This work illustrates the fact that Cu intercalation is harmful for graphene grown on Ir(111) at the atomic scale.

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

    Science.gov (United States)

    König, Thomas; Simon, Georg H; Heinke, Lars; Lichtenstein, Leonid; Heyde, Markus

    2011-01-01

    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., F(0), F(+), F(2+) 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 F(2+)-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.

  7. Scanning tunneling microscopy and spectroscopy of finite-size twisted bilayer graphene

    Science.gov (United States)

    Wang, Wen-Xiao; Jiang, Hua; Zhang, Yu; Li, Si-Yu; Liu, Haiwen; Li, Xinqi; Wu, Xiaosong; He, Lin

    2017-09-01

    Finite-size twisted bilayer graphene (TBG, where here the TBG is of nanoscale size) is quite unstable and will change its structure to a Bernal (or A B -stacking) bilayer with a much lower energy. Therefore, the lack of finite-size TBG makes its electronic properties difficult to access in experiments. In this paper, a special confined TBG is obtained in the overlaid area of two continuous misoriented graphene sheets. The width of the confined region of the TBG changes gradually from about 22 to 0 nm. By using scanning tunneling microscopy, we study carefully the structure and the electronic properties of finite-size TBG. Our results indicate that the low-energy electronic properties, including twist-induced Van Hove singularities (VHSs) and spatial modulation of the local density of states, are strongly affected by the translational symmetry breaking of the finite-size TBG. However, the electronic properties above the energy of the VHSs are almost not influenced by quantum confinement even when the width of the TBG is reduced to only a single moiré spot.

  8. TOPICAL REVIEW: Active nanocharacterization of nanofunctional materials by scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Daisuke Fujita and Keisuke Sagisaka

    2008-01-01

    Full Text Available Recent developments in the application of scanning tunneling microscopy (STM to nanofabrication and nanocharacterization are reviewed. The main focus of this paper is to outline techniques for depositing and manipulating nanometer-scale structures using STM tips. Firstly, the transfer of STM tip material through the application of voltage pulses is introduced. The highly reproducible fabrication of metallic silver nanodots and nanowires is discussed. The mechanism is thought to be spontaneous point-contact formation caused by field-enhanced diffusion to the apex of the tip. Transfer through the application of z-direction pulses is also introduced. Sub-nanometer displacement pulses along the z-direction form point contacts that can be used for reproducible nanodot deposition. Next, the discovery of the STM structural manipulation of surface phases is discussed. It has been demonstrated that superstructures on Si(001 surfaces can be reverse-manipulated by controlling the injected carriers. Finally, the fabrication of an atomic-scale one-dimensional quantum confinement system by single-atom deposition using a controlled point contact is presented. Because of its combined nanofabrication and nanocharacterization capabilities, STM is a powerful tool for exploring the nanotechnology and nanoscience fields.

  9. Scanning Tunneling Microscopy Study of a Vicinal Anatase TiO2 Surface

    Science.gov (United States)

    Li, Shao-Chun; Dulub, Olga; Diebold, Ulrike

    2009-03-01

    Titanium dioxide finds versatile applications in various technical fields including gas sensing, coatings, pigments, heterogeneous catalysis, photocatalytic degradation of pollutants, and solar cells. TiO2 is found in three main crystallographic phases: rutile, anatase and brookite. Rutile is the thermodynamically most stable form and is considered a model system for basic research. However, anatase TiO2 is often considered to be catalytically more active than rutile for reasons not yet completely understood. In this work, using scanning tunneling microscopy (STM) and low energy electron diffraction (LEED), the structure of the anatase TiO2(5 14) surface, ˜10 vicinal to the -- lowest energy -- (101) plane, has been studied. The surface was found to facet into a structure composed of ridges with a uniform width of 5 lattice units. Based on atomically-resolved STM and electron counting rules, it is proposed that the sides of the ridges are parallel to (1 10) and (112) planes. These sides might be reconstructed to stabilize the microfaceted structure. Vapor-deposited gold shows pronounced clustering between the ridges, indicating a one-dimensional template effect of the vicinal surface, which supports denser and more uniformly sized Au clusters, as compared to the flat (101) surface.

  10. The study of transition metal surfaces and thin films with inverse photoemission and scanning tunnelling microscopy

    CERN Document Server

    Wilson, L K

    1997-01-01

    clean Cr(001) and the thick films. This suggests that hybridisation between the substrate bands and the film bands and interface induced states are significant. The spectra taken from sub-monolayer coverages of Fe show marked intensity increase at the Fermi energy, this is a feature of LDOS calculations on Fe atoms at the Fe/Cr interface. Fe growth on surfaces of Cu(100) precovered with c(2x2)N has been studied with scanning tunnelling microscopy. The images show that the Fe does not grow on areas covered with nitrogen. Two different c(2x2)N templates have been used and the shape and size of the Fe islands is seen to be altered. The unoccupied electronic states at the surface of Cr(001) have been observed using k-resolved inverse photoemission. Normal incidence IPE spectra have been taken over a range of incident electron energies (14-24 eV). The spectra show only small variation with incident energy, this is attributed to densities of states effects due to the absence of symmetry allowed initial states at th...

  11. Poor electronic screening in lightly doped Mott insulators observed with scanning tunneling microscopy

    Science.gov (United States)

    Battisti, I.; Fedoseev, V.; Bastiaans, K. M.; de la Torre, A.; Perry, R. S.; Baumberger, F.; Allan, M. P.

    2017-06-01

    The effective Mott gap measured by scanning tunneling microscopy (STM) in the lightly doped Mott insulator (Sr1-xLax) 2IrO4 differs greatly from values reported by photoemission and optical experiments. Here we show that this is a consequence of the poor electronic screening of the tip-induced electric field in this material. Such effects are well known from STM experiments on semiconductors and go under the name of tip-induced band bending (TIBB). We show that this phenomenon also exists in the lightly doped Mott insulator (Sr1-xLax) 2IrO4 and that, at doping concentrations of x ≤4 % , it causes the measured energy gap in the sample density of states to be bigger than the one measured with other techniques. We develop a model able to retrieve the intrinsic energy gap leading to a value which is in rough agreement with other experiments, bridging the apparent contradiction. At doping x ≈5 % we further observe circular features in the conductance layers that point to the emergence of a significant density of free carriers in this doping range and to the presence of a small concentration of donor atoms. We illustrate the importance of considering the presence of TIBB when doing STM experiments on correlated-electron systems and discuss the similarities and differences between STM measurements on semiconductors and lightly doped Mott insulators.

  12. 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.

  13. Dynamics of tetraphenylporphyrins on a copper (111) surface: A scanning tunneling microscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Glaessel, Stefanie; Buchner, Florian; Zillner, Elisabeth; Roeckert, Michael; Steinrueck, Hans-Peter; Marbach, Hubertus [Lehrstuhl fuer Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Universitaet Erlangen-Nuernberg, Egerlandstr. 3, D-91058 (Germany)

    2010-07-01

    The understanding of the properties of large organic molecules at surfaces is a requirement to utilize their functional properties either in single-molecule devices or in organized supramolecular architectures. Here we concentrate on the investigation of the dynamics and self-assembly of tetraphenylporphyrins (TPP) on Cu(111) using scanning tunneling microscopy (STM) in ultra-high vacuum (UHV). STM images of ordered molecular arrays and individual molecules with submolecular resolution enable to determine the supramolecular and intramolecular conformation of the porphyrins. Interestingly, 2HTPP molecules exhibit a mainly one dimensional diffusion along the main crystallographic axes of Cu(111) at room temperature, whereas CoTPP molecules form ordered arrays. Based on STM movies acquired at varying sample temperatures fundamental parameters of the molecular motion of 2HTPP on Cu(111), like the activation energy for diffusion and rotation could be estimated. These results allow a deeper understanding of the corresponding molecule-molecule and molecule-substrate interactions and thus the assembly of the observed porphyrins.

  14. Simultaneous topographic and elemental chemical and magnetic contrast in scanning tunneling microscopy

    Science.gov (United States)

    Rose, Volker; Preissner, Curt A; Hla, Saw-Wai; Wang, Kangkang; Rosenmann, Daniel

    2014-09-30

    A method and system for performing simultaneous topographic and elemental chemical and magnetic contrast analysis in a scanning, tunneling microscope. The method and system also includes nanofabricated coaxial multilayer tips with a nanoscale conducting apex and a programmable in-situ nanomanipulator to fabricate these tips and also to rotate tips controllably.

  15. Real-time scanning tunneling microscopy studies of thin film deposition and ion erosion

    NARCIS (Netherlands)

    Fokkema, Vincent

    2011-01-01

    In this thesis I present my research on the physics of some important processes in the production of thin films. I studied physical vapour deposition (PVD) and thin film modification through ion bombardment using a newly developed, high-speed scanning tunneling microscope (STM). The instrument has

  16. Scanning tunneling microscopy in TTF-TCNQ: Phase and amplitude modulated charge density waves

    DEFF Research Database (Denmark)

    Wang, Z.Z.; Gorard, J.C.; Pasquier, C.

    2003-01-01

    Charge density waves (CDWs) have been studied at the surface of a cleaved tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) single crystal using a low temperature scanning tunneling microscope (STM) under ultrahigh-vacuum conditions, between 300 and 33 K with molecular resolution. All CDW...

  17. Field-Induced Deformation as a Mechanism for Scanning Tunneling Microscopy Based Nanofabrication

    DEFF Research Database (Denmark)

    Hansen, Ole; Ravnkilde, Jan Tue; Quaade, Ulrich

    1998-01-01

    The voltage between tip and sample in a scanning tunneling microscope (STM) results in a large electric field localized near the tip apex. The mechanical stress due to this field can cause appreciable deformation of both tip and sample on the scale of the tunnel gap. We derive an approximate...... analytical expression for this deformation and confirm the validity of the result by comparison with a finite element analysis. We derive the condition for a field-induced jump to contact of tip and sample and show that this agrees well with experimental results for material transfer between tip and sample...... by voltage pulsing in ultrahigh vacuum....

  18. Cross-Sectional Scanning Tunneling Microscopy of InAsSb/InAsP Superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Allerman, A.A.; Biefeld, R.M.; Yu, E.T.; Zuo, S.L.

    1999-02-10

    Cross-sectional scanning tunneling microscopy has been used to characterize compositional structure in InAs{sub 0.87}Sb{sub 0.13}/InAs{sub 0.73}P{sub 0.27} and InAs{sub 0.83}Sb{sub 0.17}/InAs{sub 0.60}P{sub 0.40} strained-layer superlattice structures grown by metal-organic chemical vapor deposition. High-resolution STM images of the (110) cross section reveal compositional features within both the InAs{sub x}Sb{sub 1{minus}x} and InAs{sub y}P{sub 1{minus}y} alloy layers oriented along the [{bar 1}12] and [1{bar 1}2] directions--the same as those in which features would be observed for CuPt-B type ordered alloys. Typically one variant dominates in a given area, although occasionally the coexistence of both variants is observed. Furthermore, such features in the alloy layers appear to be correlated across heterojunction interfaces in a manner that provides support for III-V alloy ordering models which suggest that compositional order can arise from strain-induced order near the surface of an epitaxially growing crystal. Finally, atomically resolved (1{bar 1}0) images obtained from the InAs{sub 0.87}Sb{sub 0.13}/InAs{sub 0.73}P{sub 0.27} sample reveal compositional features in the [112] and [{bar 1}{bar 1}2] directions, i.e., those in which features would be observed for CuPt-A type ordering.

  19. A scanning tunneling microscopy based potentiometry technique and its application to the local sensing of the spin Hall effect

    OpenAIRE

    Xie, Ting; Dreyer, Michael; Bowen, David; Hinkel, Dan; Butera, R. E.; Krafft, Charles; Mayergoyz, Isaak

    2017-01-01

    A scanning tunneling microscopy based potentiometry technique for the measurements of the local surface electric potential is presented and illustrated by experiments performed on current-carrying thin tungsten films. The obtained results demonstrate a sub-millivolt resolution in the measured surface potential. The application of this potentiometry technique to the local sensing of the spin Hall effect is outlined and some experimental results are reported.

  20. Scanning tunneling microscopy study of pinning-induced vortex lattice distortion in ion-irradiated NbSe[sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Behler, S. (Inst. fuer Physik, Univ. Basel (Switzerland)); Bernasconi, M. (Inst. fuer Physik, Univ. Basel (Switzerland)); Jess, P. (Inst. fuer Physik, Univ. Basel (Switzerland)); Hofer, R. (Inst. fuer Physik, Univ. Basel (Switzerland)); Guentherodt, H.J. (Inst. fuer Physik, Univ. Basel (Switzerland)); Wirth, G. (Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany)); Wiesner, J. (Gesellschaft fuer Schwerionenforschung, Darmstadt (Germany))

    1994-04-01

    We observe vortex pinning in 2.2 GeV Au-ion irradiated NbSe[sub 2] by scanning tunneling microscopy (STM) at 3 K. The ion irradiation generates columnar defects which act as pinning sites. At various external magnetic fields the vortex arrangement is clearly resolved but shows strong distortion. The location of individual defects is extracted from STM data and compared to the vortex arrangement. (orig.)

  1. The tip-sample water bridge and light emission from scanning tunnelling microscopy

    OpenAIRE

    Boyle, Michael G; Mitra, J; Dawson, Paul

    2009-01-01

    Light emission spectrum from a scanning tunnelling microscope (LESTM) is investigated as a function of relative humidity and shown to be a novel and sensitive means for probing the growth and properties of a water meniscus in the nm-scale. An empirical model of the light emission process is formulated and applied successfully to replicate the decay in light intensity and spectral changes observed with increasing relative humidity. The modelling indicates a progressive water filling of the tip...

  2. Local analysis of semiconductor nanoobjects by scanning tunneling atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Natalia A. Lashkova

    2015-03-01

    Full Text Available The features of the current–voltage (I–V measurements in local regions of semiconductor nanostructures by conductive atomic force microscopy (AFM are discussed. The standard procedure of I–V measurements in conductive AFM leads not infrequently to the thermomechanical stresses in the sample and, as a consequence, nonreproducibility and unreliability of measurements. The technique of obtaining reproducible current–voltage characteristics is proposed. According to the technique, a series of measurements of the selected scanning area in the mode of conducting AFM should be taken, each at the certain value of the potential. According to a series of scans I–V curve at a particular point (for any point of the scan was plotted. The program is realized in the LabVIEW software. The proposed method extends the capabilities of scanning probe microscopy in the diagnosis of nanostructured semiconductor materials.

  3. Surface polymerization of (3,4-ethylenedioxythiophene) probed by in situ scanning tunneling microscopy on Au(111) in ionic liquids.

    Science.gov (United States)

    Ahmad, Shahzada; Carstens, Timo; Berger, Rüdiger; Butt, Hans-Jürgen; Endres, Frank

    2011-01-01

    The electropolymerization of 3,4-ethylenedioxythiophene (EDOT) to poly(3,4-ethylenedioxythiophene) (PEDOT) was investigated in the air and water-stable ionic liquids 1-hexyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate [HMIm]FAP and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide [EMIm]TFSA. In situ scanning tunnelling microscopy (STM) results show that the electropolymerization of EDOT in the ionic liquid can be probed on the nanoscale. In contrast to present understanding, it was observed that the EDOT can be oxidised in ionic liquids well below its oxidation potential and the under potential growth of polymer was visualized by in situ STM. These results serve as the first study to confirm the under potential growth of conducting polymers in ionic liquids. Furthermore, ex situ microscopy measurements were performed. Quite a high current of 670 nA was observed on the nanoscale by conductive scanning force microscopy (CSFM).

  4. Investigating Atomic Scale Disordered Stripes in the Cuprate Superconductors with Scanning Tunneling Microscopy

    Science.gov (United States)

    Main, Elizabeth

    The high-Tc cuprate superconductors have been studied for 25 years in the search for the mechanism underlying their superconductivity. In the process, experiments learned that the correlated electrons in these materials organize themselves in a variety of patterns. One such pattern is a type of short-range charge modulations that exist both in and outside of the superconducting phase, which has been linked to the cuprate pseudogap phase. In optimal and slightly underdoped Bi2Sr 2CuO6+delta this charge order (labeled Q*) has wavelength ˜ 5a0. A second and, I argue, related order (Q**) has wavelength of ˜1.25a0. These modulations are highly disordered and for this reason their nature is not fully understood. In this thesis I use scanning tunneling microscopy (STM) to study the disorder of these charge modulations, as an avenue to understanding the nature of the charge order itself. Locally, the charge modulations have a preferred orientation, with a wavevector pointing along one crystal axis or the other. But globally, there is no preferred direction. Our most striking finding is that the local orientation is the same for the Q* and Q** orders, strong new evidence that these two types of charge modulations have the same physical cause. Next, we find that Q* and Q** are subject to two kinds of disorder. Disorder in the optimal local wavelength competes with defect pinning of crests and troughs to produce the disordered modulations that we see. To get our final result, I view the local orientation of the charge modulations as an Ising spin, and compare the resulting Ising maps to theoretical predictions for different classes of disorder. I find the disorder to be consistent with 3D Random Field disorder. New analytical tools were necessary to carry out these measurements. I describe a new algorithm to map the local wavevector of a modulation. Then I present a second new algorithm to correct an STM image for the effects of a slightly anisotropic tip, This thesis also

  5. Co on Pt(111) studied by spin-polarized scanning tunneling microscopy and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Meier, F.K.

    2006-07-01

    In this thesis the electronic properties of the bare Pt(111) surface, the structural, electronic, and magnetic properties of monolayer and double-layer high Co nanostructures as well as the spin-averaged electronic structure of single Co atoms on Pt(111) were studied by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). The experiments on the bare Pt(111) surface and on single Co atoms have been performed in an STM facility operating at temperatures of down to 0.3 K and at magnetic fields of up to 14 T under ultra-high vacuum conditions. The facility has been taken into operation within the time period of this thesis and its specifications were tested by STS measurements. These characterization measurements show a very high stability of the tunneling junction and an energy resolution of about 100 {mu}eV, which is close to the thermal limit. The investigation of the electronic structure of the bare Pt(111) surface reveals the existence of an unoccupied surface state. By a comparison of the measured dispersion to first-principles electronic structure calculations the state is assigned to an sp-derived surface band at the lower boundary of the projected bulk band gap. The surface state exhibits a strong spin-orbit coupling induced spin splitting. The close vicinity to the bulk bands leads to a strong linear contribution to the dispersion and thus to a deviant appearance in the density of states in comparison to the surface states of the (111) surfaces of noble metals. A detailed study of Co monolayer and double-layer nanostructures on the Pt(111) surface shows that both kinds of nanostructures exhibit a highly inhomogeneous electronic structure which changes at the scale of only a few Aa due to a strong stacking dependence with respect to the Pt(111) substrate. With the help of first principles calculations the different spectroscopic appearance for Co atoms within the Co monolayer is assigned to a stacking dependent hybridization of Co states

  6. Electronic “Edge” State on Molybdenite Basal Plane Observed by Ultrahigh-Vacuum Scanning Tunneling Microscopy and Spectroscopy

    Science.gov (United States)

    Komiyama, Masaharu; Tomita, Hiroyuki; Yoda, Eisuke

    2007-09-01

    An electronic state heretofore unreported has been found on a cleaved basal plane of a natural molybdenite (MoS2) single crystal by ultrahigh-vacuum scanning tunneling microscopy (UHV-STM), and examined in detail both by STM and scanning tunneling spectroscopy (STS). The new electronic state resides on the edge of the upper terrace of MoS2(0001), manifesting itself in the form of bright ridges with a width of ca. 4 nm along the step edges in negatively sample-biased STM images. This ridge structure is nonexistent in STM images taken with positive sample biases. STS showed that the local density of states (LDOS) on such ridge structures is much higher than that on the terraces in the range of 0.2-1.2 eV below the Fermi edge. The nature and origin of this high LDOS at the step edges are discussed.

  7. Imaging by Electrochemical Scanning Tunneling Microscopy and Deconvolution Resolving More Details of Surfaces Nanomorphology

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    to crystallographic-surface structures. Within the wide range of new technologies, those images surface features, the electrochemical scanning tunneling microscope (ESTM) provides means of atomic resolution where the tip participates actively in the process of imaging. Two metallic surfaces influence ions trapped.......g., nanoelectronics and single-molecule probing. In principle, the ESTM is capable of sub-atomic resolution but many details at this level of magnification need further treatment of recorded data before real information is obtained. Deconvolution of the data according to the instrument response may explain some...

  8. Bimetallic Catalysts and Platinum Surfaces Studied by X-ray Absorption Spectroscopy and Scanning Tunnelling Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roenning, Magnus

    2000-07-01

    Bimetallic catalyst systems used in Fischer-Tropsch synthesis (Co-Re/Al{sub 2}O{sub 3}) and in the naphtha reforming process (Pt-Re/Al{sub 2}O{sub 3}) have been studied in situ using X-ray absorption spectroscopy (EXAFS). Additionally, the adsorption of ethene on platinum single crystal surfaces has been investigated using scanning tunnelling microscopy. In situ EXAFS at the cobalt K absorption edge have been carried out at 450{sup o}C on the hydrogen reduction of a rhenium-promoted Co{sub 3}O{sub 4}/Al{sub 2}O{sub 3} catalyst. Reductions carried out using 100% hydrogen and 5% hydrogen in helium gave different results. Whereas the reduction using dilute hydrogen leads to bulk-like metallic cobalt particles (hcp or fcc), reaction with pure hydrogen yields a more dispersed system with smaller cobalt metal particles (< 40 A). The results are rationalised in terms of different degrees of reoxidation of cobalt by the higher and lower concentrations of water generated during the reduction of cobalt oxide by 100% and 5% hydrogen, respectively. Additionally, in both reduction protocols a small fraction (3 -4 wt%) of the cobalt content is randomly dispersed over the tetrahedral vacancies of the alumina support. This dispersion occurs during reduction and not calcination. The cobalt in these sites cannot be reduced at 450 {sup o}C. The local environments about the rhenium atoms in Co-Re/{gamma}-A1{sub 2}O{sub 3} catalyst after different reduction periods have been studied by X-ray absorption spectroscopy. A bimetallic catalyst containing 4.6 wt% cobalt and 2 wt% rhenium has been compared with a corresponding monometallic sample with 2 wt% rhenium on the same support. The rhenium L{sub III} EXAFS analysis shows that bimetallic particles are formed after reduction at 450{sup o}C with the average particle size being 10-15 A. Rhenium is shown to be reduced at a later stage than cobalt. The fraction of cobalt atoms entering the support obstructs the access to the support for the

  9. Adsorbate structures and catalytic reactions studied in the torrpressure range by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Kevin Shao-Lin [Univ. of California, Berkeley, CA (United States)

    2003-01-01

    High-pressure, high-temperature scanning tunneling microscopy (HPHTSTM) was used to study adsorbate structures and reactions on single crystal model catalytic systems. Studies of the automobile catalytic converter reaction [CO + NO → 1/2 N2 + CO2] on Rh(111) and ethylene hydrogenation [C2H4 + H2 → C2H6] on Rh(111) and Pt(111) elucidated information on adsorbate structures in equilibrium with high-pressure gas and the relationship of atomic and molecular mobility to chemistry. STM studies of NO on Rh(111) showed that adsorbed NO forms two high-pressure structures, with the phase transformation from the (2 x 2) structure to the (3 x 3) structure occurring at 0.03 Torr. The (3 x 3) structure only exists when the surface is in equilibrium with the gas phase. The heat of adsorption of this new structure was determined by measuring the pressures and temperatures at which both (2 x 2) and (3 x 3) structures coexisted. The energy barrier between the two structures was calculated by observing the time necessary for the phase transformation to take place. High-pressure STM studies of the coadsorption of CO and NO on Rh(111) showed that CO and NO form a mixed (2 x 2) structure at low NO partial pressures. By comparing surface and gas compositions, the adsorption energy difference between topsite CO and NO was calculated. Occasionally there is exchange between top-site CO and NO, for which we have described a mechanism for. At high NO partial pressures, NO segregates into islands, where the phase transformation to the (3 x 3) structure occurs. The reaction of CO and NO on Rh(111) was monitored by mass spectrometry (MS) and HPHTSTM. From MS studies the apparent activation energy of the catalytic converter reaction was calculated and compared to theory. STM showed that under high-temperature reaction conditions, surface metal atoms become mobile. Ethylene hydrogenation and its poisoning by CO was

  10. Surface damage through grazing incidence ions investigated by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Redinger, Alex

    2009-07-10

    Surface damage, caused by grazing incidence ions, is investigated with variable temperature scanning tunneling microscopy. The experiments are carried out on a Pt(111) crystal. The kinetic energy of noble gas ions is varied between 1-15 keV and the angle of incidence can be adjusted between {theta} = 78.5 and {theta} = 90 measured with respect to the surface normal. The damage patterns of single ion impacts, on flat terraces and at step edges of monoatomic height, are investigated at low surface temperatures. Ions hitting a flat terrace are usually specular reflected. The energy transfer from the ion to the crystal atoms is small and only little damage is produced. In contrast, at ascending step edges, which are illuminated by the ion beam, large angle scattering events occur. Sputtering, adatom and vacancy production is induced. However, a significant fraction of the ions, which hit step edges, enter the crystal and are guided in between two atomic layers parallel to the surface via small angle binary collisions. This steering process is denoted as subsurface channeling. The energy loss per length scale of the channeled particles is low, which results in long ion trajectories (up to 1000A). During the steering process, the ions produce surface damage. Depending on the ion species and the ion energy, adatom and vacancies or surface vacancy trenches of monoatomic width are observed. The surface damage can be used to track the path of the ion. This makes the whole trajectory of single ions with keV energy visible. The number of sputtered atoms per incident ion at ascending step edges, i.e. the step edge sputtering yield, is measured experimentally for different irradiation conditions. For {theta} = 86 , the sputtering yield is determined from the fluence dependent retraction of pre-existing illuminated step edges. An alternative method for the step edge sputtering yield determination, is the analysis of the concentration of ascending steps and of the removed amount

  11. Chain-like structure elements in Ni40Ta60 metallic glasses observed by scanning tunneling microscopy.

    Science.gov (United States)

    Pawlak, Rémy; Marot, Laurent; Sadeghi, Ali; Kawai, Shigeki; Glatzel, Thilo; Reimann, Peter; Goedecker, Stefan; Güntherodt, Hans-Joachim; Meyer, Ernst

    2015-08-13

    The structure of metallic glasses is a long-standing question because the lack of long-range order makes diffraction based techniques difficult to be applied. Here, we used scanning tunneling microscopy with large tunneling resistance of 6 GΩ at low temperature in order to minimize forces between probe and sample and reduce thermal fluctuations of metastable structures. Under these extremely gentle conditions, atomic structures of Ni40Ta60 metallic glasses are revealed with unprecedented lateral resolution. In agreement with previous models and experiments, icosahedral-like clusters are observed. The clusters show a high degree of mobility, which explains the need of low temperatures for stable imaging. In addition to icosahedrons, chain-like structures are resolved and comparative density functional theory (DFT) calculations confirm that these structures are meta-stable. The co-existence of icosahedral and chain-like structures might be an key ingredient for the understanding of the mechanical properties of metallic glasses.

  12. In situ high-temperature scanning tunneling microscopy study of bilayer graphene growth on 6H-SiC(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Yuya [Dept. Materials Science and Engineering, University of California Los Angeles, Los Angeles, CA 90095 (United States); Petrova, V.; Petrov, I. [Frederick-Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 61801 (United States); Kodambaka, S., E-mail: kodambaka@ucla.edu [Dept. Materials Science and Engineering, University of California Los Angeles, Los Angeles, CA 90095 (United States)

    2012-06-01

    Using in situ high-temperature (1395 K), ultra-high vacuum, scanning tunneling microscopy (STM), we investigated the growth of bilayer graphene on 6H-SiC(0001). From the STM images, we measured areal coverages of SiC and graphene as a function of annealing time and found that graphene grows at the expense of SiC. Graphene domains were observed to grow, at comparable rates, at (I) graphene-free SiC step edges, (II) graphene-SiC interfaces, and (III) the existing graphene domain edges. Based upon our results, we suggest that the rate-limiting step controlling bilayer graphene growth is the desorption of Si from the substrate. - Highlights: Black-Right-Pointing-Pointer Use of scanning tunneling microscopy at temperatures as high as 1395 K. Black-Right-Pointing-Pointer Direct observation of graphene formation on SiC surfaces at the growth temperature. Black-Right-Pointing-Pointer Identification of atomic-scale pathways for bilayer graphene growth.

  13. High-Resolution Imaging of Polyethylene Glycol Coated Dendrimers via Combined Atomic Force and Scanning Tunneling Microscopy

    Directory of Open Access Journals (Sweden)

    Shawn Riechers

    2015-01-01

    Full Text Available Dendrimers have shown great promise as drug delivery vehicles in recent years because they can be synthesized with designed size and functionalities for optimal transportation, targeting, and biocompatibility. One of the most well-known termini used for biocompatibility is polyethylene glycol (PEG, whose performance is affected by its actual conformation. However, the conformation of individual PEG bound to soft materials such as dendrimers has not been directly observed. Using atomic force microscopy (AFM and scanning tunneling microscopy (STM, this work characterizes the structure adopted by PEGylated dendrimers with the highest resolution reported to date. AFM imaging enables visualization of the individual dendrimers, as well as the differentiation and characterization of the dendrimer core and PEG shell. STM provides direct imaging of the PEG extensions with high-resolution. Collectively, this investigation provides important insight into the structure of coated dendrimers, which is crucial for the design and development of better drug delivery vehicles.

  14. Analysis and Calibration of in situ scanning tunnelling microscopy Images with atomic Resolution Influenced by Surface Drift Phenomena

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Møller, Per

    1994-01-01

    The influence of surface drift velocities on in situ scanning tunnelling microscopy (STM) experiments with atomic resolution is analysed experimentally and mathematically. Constant drift velocities much smaller than the speed of scanning can in many in situ STM experiments with atomic resolution...... result in an apparent surface reconstruction. It is shown that a surface atomic structure can be distorted and observed as another atomic structure entirely owing to a constant drift velocity in the plane of the surface. The image can be resolved mathematically and the components of the drift velocity...... as well as the vectors of the non-distorted surface lattice can be determined. The calibration of distances can thus be carried out also when the image is influenced by drift. Results with gold surfaces and graphite surfaces are analysed and discussed....

  15. Scanning Tunneling Microscopy Studies of Crystalline Hydrogenation of Graphene Grown on Cu(111)

    Science.gov (United States)

    Tjung, Steven J.; Gambrel, Grady A.; Hollen, Shawna M.; Gupta, Jay A.

    Because of the sensitivity of 2D material surfaces, chemical functionalization can be exploited to tune the electronic structure of these materials. For example, hydrogen bonding to carbon atoms in graphene tunes the material from a semi-metal to a wide-gap insulator. We developed a method for a reproducible epitaxial growth of graphene on Cu(111) in the ultra-high vacuum chamber of a scanning tunneling microscope (STM). We find that hydrogen atoms can be bonded to the graphene in a nanoscale region using a novel field-emission process, whereby physisorbed H2 is cracked in situ using the STM tip. This method produced crystalline surfaces of hydrogen-terminated graphene with 4.2Å lattice, which has proven difficult to produce using conventional atomic beam methods which typically produced disordered hydrogenation. Additionally, this hydrogenation process is reversible and we are able to recover the pristine graphene by H desorption during STM imaging at a high bias. STM images after the dehydrogenation process showed the same atomic lattice and Moiré pattern as the pristine graphene, with the exception of additional point defects. STM spectra show the suppression of the Cu surface state on the hydrogenated graphene, but the opening of a wide-gap was not observed. Funded by the Center for Emergent Materials at the Ohio State University, an NSF MRSEC (Grant No. DMR-1420451 and DMR-0820414).

  16. Attractive interaction between Mn atoms on the GaAs(110) surface observed by scanning tunneling microscopy.

    Science.gov (United States)

    Taninaka, Atsushi; Yoshida, Shoji; Kanazawa, Ken; Hayaki, Eiko; Takeuchi, Osamu; Shigekawa, Hidemi

    2016-06-16

    Scanning tunneling microscopy/spectroscopy (STM/STS) was carried out to investigate the structures of Mn atoms deposited on a GaAs(110) surface at room temperature to directly observe the characteristics of interactions between Mn atoms in GaAs. Mn atoms were paired with a probability higher than the random distribution, indicating an attractive interaction between them. In fact, re-pairing of unpaired Mn atoms was observed during STS measurement. The pair initially had a new structure, which was transformed during STS measurement into one of those formed by atom manipulation at 4 K. Mn atoms in pairs and trimers were aligned in the direction, which is theoretically predicted to produce a high Curie temperature.

  17. Strongly compressed Bi (111) bilayer films on Bi{sub 2}Se{sub 3} studied by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, K. F.; Yang, Fang; Song, Y. R. [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Canhua; Qian, Dong; Gao, C. L.; Jia, Jin-Feng [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093 (China)

    2015-09-21

    Ultra-thin Bi films show exotic electronic structure and novel quantum effects, especially the widely studied Bi (111) film. Using reflection high-energy electron diffraction and scanning tunneling microscopy, we studied the structure and morphology evolution of Bi (111) thin films grown on Bi{sub 2}Se{sub 3}. A strongly compressed, but quickly released in-plane lattice of Bi (111) is found in the first three bilayers. The first bilayer of Bi shows a fractal growth mode with flat surface, while the second and third bilayer show a periodic buckling due to the strong compression of the in-plane lattice. The lattice slowly changes to its bulk value with further deposition of Bi.

  18. Mn doped InSb studied at the atomic scale by cross-sectional scanning tunneling microscopy

    Science.gov (United States)

    Mauger, S. J. C.; Bocquel, J.; Koenraad, P. M.; Feeser, C. E.; Parashar, N. D.; Wessels, B. W.

    2015-11-01

    We present an atomically resolved study of metal-organic vapor epitaxy grown Mn doped InSb. Both topographic and spectroscopic measurements have been performed by cross-sectional scanning tunneling microscopy (STM). The measurements on the Mn doped InSb samples show a perfect crystal structure without any precipitates and reveal that Mn acts as a shallow acceptor. The Mn concentration of the order of ˜1020 cm-3 obtained from the cross-sectional STM data compare well with the intended doping concentration. While the pair correlation function of the Mn atoms showed that their local distribution is uncorrelated beyond the STM resolution for observing individual dopants, disorder in the Mn ion location giving rise to percolation pathways is clearly noted. The amount of clustering that we see is thus as expected for a fully randomly disordered distribution of the Mn atoms and no enhanced clustering or second phase material was observed.

  19. GaSb/GaAs quantum dot formation and demolition studied with cross-sectional scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Smakman, E. P.; Garleff, J. K.; Rambabu, P.; Koenraad, P. M. [Department of Applied Physics, Eindhoven University of Technology, Eindhoven 5612 AZ (Netherlands); Young, R. J.; Hayne, M. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

    2012-04-02

    We present a cross-sectional scanning tunneling microscopy study of GaSb/GaAs quantum dots grown by molecular beam epitaxy. Various nanostructures are observed as a function of the growth parameters. During growth, relaxation of the high local strain fields of the nanostructures plays an important role in their formation. Pyramidal dots with a high Sb content are often accompanied by threading dislocations above them. GaSb ring formation is favored by the use of a thin GaAs first cap layer and a high growth temperature of the second cap layer. At these capping conditions, strain-driven Sb diffusion combined with As/Sb exchange and Sb segregation remove the center of a nanostructure, creating a ring. Clusters of GaSb without a well defined morphology also appear regularly, often with a highly inhomogeneous structure which is sometimes divided up in fragments.

  20. Hydrophilicity and Microsolvation of an Organic Molecule Resolved on the Sub-molecular Level by Scanning Tunneling Microscopy.

    Science.gov (United States)

    Lucht, Karsten; Loose, Dirk; Ruschmeier, Maximilian; Strotkötter, Valerie; Dyker, Gerald; Morgenstern, Karina

    2018-01-26

    Low-temperature scanning tunneling microscopy was used to follow the formation of a solvation shell around an adsorbed functionalized azo dye from the attachment of the first water molecule to a fully solvated molecule. Specific functional groups bind initially one water molecule each, which act as anchor points for additional water molecules. Further water attachment occurs in areas close to these functional groups even when the functional groups themselves are already saturated. In contrast, water molecules surround the hydrophobic parts of the molecule only when the two-dimensional solvation shell closes around them. This study thus traces hydrophilic and hydrophobic properties of an organic molecule down to a sub-molecular length scale. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Thermal Motion of Steps and Vacancies in SILICON(001) by Scanning Tunneling Microscopy

    Science.gov (United States)

    Kitamura, Nobuyoshi

    Thermal motion of steps and vacancies plays important roles in surface kinetic processes. Using a scanning tunneling microscope with the new capability to image heated samples, we have conducted direct observations of the motion of monatomic-height steps and vacancies on Si(001) at the atomic level in the temperature range of 490 to 530K. We clarify behaviors of steps and vacancies specific to the Si(001) surface. The tip-to-sample drift caused by the sample heating has been reduced to about 0.01 A/sec by applying linear voltage ramps with a precisely adjusted rate to the piezo tube scanner. The low drift rate allows detailed analyses of individual structural changes at steps and vacancies within the same region for ~ 1 hour. We find that motion of vacancies is predominantly along the dimer rows, and that creation and annihilation events occur in the terraces rather than at steps. In particular, diffusion of the single-dimer vacancy has been analyzed in detail, and an activation energy of 1.7 +/- 0.4 eV has been measured for its diffusion. Structural changes at steps are observed at the ends of dimer rows as either additions or deletions of a pair of dimers. We observe that changes mainly occur nearby kinks and those of the same sign are clustered together. It is shown that these changes involve nucleation or dissociation of dimers and long range transport of monomers, and that they are inconsistent with random nucleation and dissociation of dimers. All the observations are quantitatively reproduced by a Metropolis Monte Carlo simulation with a Hamiltonian containing only kink and corner energies. By classifying the elementary reactions at steps based on the same Hamiltonian, we find that hopping of a unit kink along the step is the predominant type of reactions. This finding leads to a simple explanation for all the observations. At our temperatures, changes at steps are governed by energy differences among local configurations, which are only on the order of 0

  2. Scanning Tunneling Microscopy of Charge Density Wave Structure in Tantalum Disulfide

    Science.gov (United States)

    Thomson, Ruth Ellen

    I have used a scanning tunneling microscope (STM) to image simultaneously the atomic lattice and the charge density wave (CDW) superstructure in tantalum disulfide (1T-TaS_2) over the temperature range of 370-77K. In the lowest temperature (commensurate) phase, present below 180K, the CDW is at an angle of 13.9 ^circ relative to the lattice and is uniformly commensurate. In the incommensurate phase, present above 353K, the CDW is aligned with the lattice. 1T-TaS_2 exhibits two other phases; the triclinic (T) phase which is present between 223K and 283K upon warming the sample, and the nearly-commensurate (NC) phase which is present between 353K and 180K upon cooling the sample and between 283K and 353K upon warming the sample. In both of these phases, discommensurate models where the CDW is arranged in small commensurate domains have been proposed. In the NC phase the CDW is rotated between 10^circ and 12.5 ^circ relative to the atomic lattice. Such a rotated CDW would create an interference pattern with the underlying atomic lattice regardless of the existence of a true domain superstructure. Previous work on 1T-TaS _2 has not adequately accounted for the possibility of the moire pattern. However, around each fundamental CDW peak in the Fourier transform of the real space STM images, several satellite spots are visible, which conclusively prove the existence of domains in the NC phase. In the T phase, STM images clearly show discommensurations and domains of the CDW which are verified by the satellite spots in the Fourier transform. However, the shape and size of these domains do not agree with those of the stretched honeycomb model proposed by Nakanishi and Shiba, but do agree with the striped model developed by my co-worker B. Burk from his new x-ray diffraction results. In addition, I report on our STM studies of two other CDW materials, blue bronze and o-TaS_3. With blue bronze we obtain STM images of the atomic structure but do not observe the CDW. With o

  3. In silico simulations of tunneling barrier measurements for molecular orbital-mediated junctions: A molecular orbital theory approach to scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Terryn, Raymond J.; Sriraman, Krishnan; Olson, Joel A., E-mail: jolson@fit.edu; Baum, J. Clayton, E-mail: cbaum@fit.edu [Department of Chemistry, Florida Institute of Technology, 150 West University Boulevard, Melbourne, Florida 32901 (United States); Novak, Mark J. [Department of Chemistry and Applied Biological Sciences, South Dakota School of Mines and Technology, 501 E. Saint Joseph Street, Rapid City, South Dakota 57701 (United States)

    2016-09-15

    A new simulator for scanning tunneling microscopy (STM) is presented based on the linear combination of atomic orbitals molecular orbital (LCAO-MO) approximation for the effective tunneling Hamiltonian, which leads to the convolution integral when applied to the tip interaction with the sample. This approach intrinsically includes the structure of the STM tip. Through this mechanical emulation and the tip-inclusive convolution model, dI/dz images for molecular orbitals (which are closely associated with apparent barrier height, ϕ{sub ap}) are reported for the first time. For molecular adsorbates whose experimental topographic images correspond well to isolated-molecule quantum chemistry calculations, the simulator makes accurate predictions, as illustrated by various cases. Distortions in these images due to the tip are shown to be in accord with those observed experimentally and predicted by other ab initio considerations of tip structure. Simulations of the tunneling current dI/dz images are in strong agreement with experiment. The theoretical framework provides a solid foundation which may be applied to LCAO cluster models of adsorbate–substrate systems, and is extendable to emulate several aspects of functional STM operation.

  4. Development and set-up of a new low temperature scanning tunneling microscope Applications on microscopy and spectroscopy of lanthanid metals

    CERN Document Server

    Mühlig, A

    2000-01-01

    Scanning tunneling microscopy and spectroscopy are suitable methods to study the physical properties of thin magnetic metal films with a thickness of a few monolayers. These systems are of current interest because they give insight into solids states physics of metals. This thesis deals with following subjects: Introduction to scanning tunneling microscopy. Set-up of a low temperatur scanning tunneling microscope. Growth of thin Co and lanthanid metal films on W(110). Interplay of morphologie and magnetism on the example of Co/W(110). Making of Gd wires which are only a few nanometers thin. Diskussion of the studied exchange splitting of a d-like surface state in a local moment magnet. Measurement of the lifetime of hot holes and hot electrons near the fermi edge.

  5. Electrochemistry and in situ scanning tunnelling microscopy of pure and redox-marked DNA- and UNA-based oligonucleotides on Au(111)-electrode surfaces

    DEFF Research Database (Denmark)

    Hansen, Allan Glargaard; Salvatore, Princia; Karlsen, K.

    2013-01-01

    We have studied adsorption and electrochemical electron transfer of several 13- and 15-base DNA and UNA (unlocked nucleic acids) oligonucleotides (ONs) linked to Au(111)-electrode surfaces via a 50-C6-SH group using cyclic voltammetry (CV) and scanning tunnelling microscopy in aqueous buffer unde...

  6. Cobalt Chemical Vapor Deposition Process on Molybdenite Basal Plane Observed by Ultrahigh-Vacuum Scanning Tunneling Microscopy

    Science.gov (United States)

    Komiyama, Masaharu; Kiyohara, Kohei; Yoda, Eisuke; Kubota, Takeshi; Okamoto, Yasuaki

    2005-07-01

    The processes of high-temperature (473 K) resulfidation and cobalt carbonyl adsorption by chemical vapor deposition (CVD) on a cleaved basal plane of a natural molybdenite (MoS2) single crystal were examined by ultrahigh-vacuum scanning tunneling microscopy (UHV-STM) on the nanometer scale. The resulfided cleaved molybdenite basal plane showed a displacement of upper terraces, and a sinusoidal structure at step edges, both of which may be caused by the electronic effect at the surface. Cobalt carbonyl appeared to be adsorbed at both the S- and Mo-terminated edges, resulting in an agglomeration at the step edges on lower terraces with a width of a few tens of nanometers. When this surface with adsorbed carbonyl was sulfided at 513 K for 1 h, most of the adsorbed carbonyl clusters appeared to be desorbed while a small part were dispersed on the terraces in small clusters of 10-20 nm in size. The obtained results are discussed in terms of the preparation of Co-Mo hydrodesulfurization (HDS) catalysts.

  7. Defect-like structures of graphene on copper foils for strain relief investigated by high-resolution scanning tunneling microscopy.

    Science.gov (United States)

    Zhang, Yanfeng; Gao, Teng; Gao, Yabo; Xie, Shubao; Ji, Qingqing; Yan, Kai; Peng, Hailin; Liu, Zhongfan

    2011-05-24

    Understanding of the continuity and the microscopic structure of as-grown graphene on Cu foils through the chemical vapor deposition (CVD) method is of fundamental significance for optimizing the growth parameters toward high-quality graphene. Because of the corrugated nature of the Cu foil surface, few experimental efforts on this issue have been made so far. We present here a high-resolution scanning tunneling microscopy (STM) study of CVD graphene directly on Cu foils. Our work indicates that graphene can be grown with a perfect continuity extending over both crystalline and noncrystalline regions, highly suggestive of weak graphene-substrate interactions. Due to thermal expansion mismatch, defect-like wrinkles and ripples tend to evolve either along the boundaries of crystalline terraces or on noncrystalline areas for strain relief. Furthermore, the strain effect arising from the conforming of perfect two-dimensional graphene to the highly corrugated surface of Cu foils is found to induce local bonding configuration change of carbon from sp(2) to sp(3), evidenced by the formation of "three-for-six" lattices.

  8. Atomic mechanism for the growth of wafer-scale single-crystal graphene: theoretical perspective and scanning tunneling microscopy investigations

    Science.gov (United States)

    Niu, Tianchao; Zhang, Jialin; Chen, Wei

    2017-12-01

    Chemical vapor deposition (CVD) is the most promising approach for producing low-cost, high-quality, and large area graphene. Revealing the graphene growth mechanism at the atomic-scale is of great importance for realizing single crystal graphene (SCG) over wafer scale. Density functional theoretical (DFT) calculations are playing an increasingly important role in revealing the structure of the most stable carbon species, understanding the evolution processes, and disclosing the active sites. Scanning tunneling microscopy (STM) is a powerful surface characterization tool to illustrate the real space distribution and atomic structures of growth intermediates during the CVD process. Combining them together can provide valuable information to improve the atomically controlled growth of SCG. Starting from a basic concept of the substrate effect on realizing SCG, this review covers the progress made in theoretical investigations on various carbon species during graphene growth on different transition metal substrates, in the STM study of the structural intermediates on transition metal surfaces, and in synthesizing graphene nanoribbons with atomic-precise width and edge structure, ending with a perspective on the future development of 2D materials beyond graphene.

  9. High resolution in situ magneto-optic Kerr effect and scanning tunneling microscopy setup with all optical components in UHV.

    Science.gov (United States)

    Lehnert, A; Buluschek, P; Weiss, N; Giesecke, J; Treier, M; Rusponi, S; Brune, H

    2009-02-01

    A surface magneto-optic Kerr effect (MOKE) setup fully integrated in an ultrahigh vacuum chamber is presented. The system has been designed to combine in situ MOKE and scanning tunneling microscopy. Magnetic fields up to 0.3 T can be applied at any angle in the transverse plane allowing the study of in-plane and out-of-plane magnetization. The setup performance is demonstrated for a continuous film of 0.9 monolayers (ML) Co/Rh(111) with in-plane easy axis and for a superlattice of nanometric double layer Co islands on Au(11,12,12) with out-of-plane easy axis. For Co/Au(11,12,12) we demonstrate that the magnetic anisotropy energies deduced from thermally induced magnetization reversal and from applying a torque onto the magnetization by turning the field are the same. For the presented setup we establish a coverage detection limit of 0.5 ML for transverse and 0.1 ML for polar MOKE. For island superlattices with the density of Co/Au(11,12,12), the latter limit corresponds to islands composed of about 50 atoms. The detection limit can be further reduced when optimizing the MOKE setup for either one of the two Kerr configurations.

  10. Scanning tunneling microscopy of epitaxial YBa2Cu3O7 - x films prepared by thermal plasma flash evaporation method

    Science.gov (United States)

    Hayasaki, Kei; Takamura, Yuzuru; Yamaguchi, Norio; Terashima, Kazuo; Yoshida, Toyonobu

    1997-02-01

    The surface morphology of epitaxial YBa2Cuoverflow="scroll">3O7-x films prepared by thermal plasma flash evaporation was extensively investigated by scanning tunneling microscopy. Under epitaxial film growth conditions with the deposition rate up to 0.42 μm/min, two-dimensional nucleus growth and spiral growth were observed. The main deposition species in this process was found to be the cluster ranging from 0.3 to 9 nm and the size of the cluster influenced the growth mode strongly. Theoretical analysis based on the two-dimensional critical radius revealed that smaller clusters became weakly bonded nuclei resulting in spiral growth and larger clusters became stable nuclei resulting in two-dimensional nucleus growth, which we named two-dimensional cluster nucleus growth. The clusters generated in the plasma boundary layer undoubtedly involve sufficient energy necessary for crystallization and show quite different characteristics from those of the clusters generated in vacuum by adiabatic expansion process. Hence, this process must be named "hot cluster epitaxy.''

  11. Scanning tunneling microscopy and spectroscopy study of the patchwork structure in Pt doped IrTe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Fujisawa, Y., E-mail: 1215702@ed.tus.ac.jp [Department of Physics, Tokyo University of Science, Shinjuku, Tokyo 162-8601 (Japan); Machida, T. [RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198 (Japan); Igarashi, K.; Kaneko, A. [Department of Physics, Tokyo University of Science, Shinjuku, Tokyo 162-8601 (Japan); Mochiku, T.; Ooi, S.; Tachiki, M.; Komori, K.; Hirata, K. [Superconducting Materials Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Sakata, H. [Department of Physics, Tokyo University of Science, Shinjuku, Tokyo 162-8601 (Japan)

    2016-11-15

    Highlights: • We performed STS measurements on patchwork structure in Ir{sub 0.93}Pt{sub 0.07}Te{sub 2}. • Patchwork structure has similar electronic features to those of IrTe{sub 2}. • Patchwork structure is caused by strain due to the dopant Pt. - Abstract: We report on the scanning tunneling microscopy (STM) and spectroscopy (STS) study on a newly discovered superconductor, Ir{sub 1−x}Pt{sub x}Te{sub 2}. We previously found that the sample which shows superconductivity forms so called “patchwork structure (PS)”. To obtain the spatial evolution of electronic structure on the PS, we performed STM/STS measurements on the PS. STS measurements revealed that an averaged spectrum shows the same energy asymmetry as that in the low temperature phase in the parent material, IrTe{sub 2}. Furthermore, the spectrum at the trough on the PS is more asymmetric than that at the crest. This tendency is similar to that observed on the supermodulation in the low temperature phase in IrTe{sub 2}.

  12. Surface structures of L10-MnGa (001) by scanning tunneling microscopy and first-principles theory

    Science.gov (United States)

    Corbett, J. P.; Guerrero-Sanchez, J.; Richard, A. L.; Ingram, D. C.; Takeuchi, N.; Smith, A. R.

    2017-11-01

    We report on the surface reconstructions of L10-ordered MnGa (001) thin films grown by molecular beam epitaxy on a 50 nm Mn3N2 (001) layer freshly grown on a magnesium oxide (001) substrate. Scanning tunneling microscopy, Auger electron spectroscopy, and reflection high energy electron diffraction are combined with first-principles density functional theory calculations to determine the reconstructions of the L10-ordered MnGa (001) surface. We find two lowest energy reconstructions of the MnGa (001) face: a 1 × 1 Ga-terminated structure and a 1 × 2 structure with a Mn replacing a Ga in the 1 × 1 Ga-terminated surface. The 1 × 2 reconstruction forms a row structure along [100]. The manganese:gallium stoichiometry within the surface based on theoretical modeling is in good agreement with experiment. Magnetic moment calculations for the two lowest energy structures reveal important surface and bulk effects leading to oscillatory total magnetization for ultra-thin MnGa (001) films.

  13. Oxidation of arsenopyrite and deposition of gold on the oxidized surfaces: A scanning probe microscopy, tunneling spectroscopy and XPS study

    Science.gov (United States)

    Mikhlin, Yuri L.; Romanchenko, Alexander S.; Asanov, Igor P.

    2006-10-01

    We have used ex situ atomic force microscopy (AFM), scanning tunneling microscopy and spectroscopy (STM/STS) and X-ray photoelectron spectroscopy (XPS) to study the surfaces of natural arsenopyrite samples that were electrochemically polarized in 1 M HCl, or leached in acidic solutions containing ferric iron salts, and then reacted with aqueous gold (III) chloride at ambient temperatures. For arsenopyrite oxidized on a positive-going potential sweep, progressively increasing amounts of surface Fe(III)-O and As-O species, and of S/Fe and S/As ratios in a non-stoichiometric sulfidic layer were found. The products formed in the sweep to a potential of 0.6 V (Ag/AgCl) of the passivity region are shaped in about 100 nm protrusions of two sorts, which are arranged in micrometer-size separate areas, while they are largely mixed at higher, "transpassive" potentials. The quantities of surface alteration substances notably decrease after leaching in ferric chloride and ferric sulfate acidic solutions. Passivation of arsenopyrite was suggested to associate with the disordered, metal-deficient surface layer having moderate excess of sulfur rather than with the products of arsenopyrite oxidation. Exposure of arsenopyrite to 10 -5-10 -3 M AuCl4- (pH 2) solutions results in the deposition of 8-50 nm gold particles; only a small fraction of the gold is present as Au(I)-S species. The electrochemical oxidation at 0.6 V or ageing of arsenopyrite in air promotes the subsequent gold deposition; in contrast, the amount of Au deposited on arsenopyrite that was treated by leaching in ferric chloride and sulfate solutions was about 10 times smaller than with polished arsenopyrite samples. It has been concluded that reducing agents formed as intermediates of arsenopyrite decomposition facilitate the Au 0 cementation although other factors related to the surface state of the arsenopyrite play a role as well. A decrease in the tunneling current magnitudes with decreasing the Au 0 particle

  14. Scanning tunneling microscopy and spectroscopy studies of the heavy-electron superconductor TlNi2Se2

    Science.gov (United States)

    Wilfert, Stefan; Schmitt, Martin; Schmidt, Henrik; Mauerer, Tobias; Sessi, Paolo; Wang, Hangdong; Mao, Qianhui; Fang, Minghu; Bode, Matthias

    2018-01-01

    We report on the structural and superconducting electronic properties of the heavy-electron superconductor TlNi2Se2 . By using a variable-temperature scanning tunneling microscopy (VT-STM) the coexistence of (√{2 }×√{2 }) R 45∘ and (2 ×1 ) surface reconstructions is observed. Similar to earlier observations on the "122" family of Fe-based superconductors, we find that their respective surface fraction strongly depends on the temperature during cleavage, the measurement temperature, and the sample's history. Cleaving at low temperature predominantly results in the (√{2 }×√{2 }) R 45∘ -reconstructed surface. A detailed analysis of the (√{2 }×√{2 }) R 45∘ -reconstructed domains identifies (2 ×1 ) -ordered dimers, tertramers, and higher order even multimers as domain walls. Higher cleaving temperatures and the warming of low-temperature-cleaved samples increases the relative weight of the (2 ×1 ) surface reconstruction. By slowly increasing the sample temperature Ts inside the VT-STM we find that the (√{2 }×√{2 }) R 45∘ surface reconstructions transforms into the (2 ×1 ) structure at Ts=123 K. We identify the polar nature of the TlNi2Se2 (001) surface as the most probable driving mechanism of the two reconstructions, as both lead to a charge density ρ =0.5 e- , thereby avoiding divergent electrostatic potentials and the resulting "polar catastrophe." Low-temperature scanning tunneling spectroscopy (STS) performed with normal metal and superconducting probe tips shows a superconducting gap which is best fit with an isotropic s wave. We could not detect any correlation between the local surface reconstruction, suggesting that the superconductivity is predominantly governed by TlNi2Se2 bulk properties. Correspondingly, temperature- and field-dependent data reveal that both the critical temperature and critical magnetic field are in good agreement with bulk values obtained earlier from transport measurements. In the superconducting state

  15. Scanning tunneling microscopy of sulfur and benzenethiol chemisorbed on Ru(0001) in 0.1 M HClO4.

    Science.gov (United States)

    Yang, Liang-Yueh Ou; Yau, Shueh-lin; Itaya, Kingo

    2004-05-25

    In situ scanning tunneling microscopy (STM) combined with linear sweep voltammetry was used to examine spatial structures of sulfur adatoms (SA) and benzenethiol (BT) molecules adsorbed on an ordered Ru(0001) electrode in 0.1 M HClO4. The Ru(0001) surface, prepared by mechanical polishing and electrochemical reduction at -1.5 V (vs RHE) in 0.1 M HClO4, contained atomically flat terraces with an average width of 20 nm. Cyclic voltammograms obtained with an as-prepared Ru(0001) electrode in 0.1 M HClO4 showed characteristics nearly identical to those of Ru(0001) treated in high vacuum. High-quality STM images were obtained for SA and BT to determine their spatial structures as a function of potential. The structure of the SA adlayer changed from (2 x mean square root of 3)rect to domain walls to (mean square root of 7 x mean square root of 7)R19.1 degrees and then to disordered as the potential was scanned from 0.3 to 0.6 V. In contrast, molecules of BT were arranged in (2 x mean square root of 3)rect between 0.1 and 0.4 V, while they were disordered at all other potentials. Adsorption of BT molecules was predominantly through the sulfur headgroup. Sulfur adatoms and adsorbed BT molecules were stable against anodic polarization up to 1.0 V (vs RHE). These two species were adsorbed so strongly that their desorption did not occur even at the onset potential for the reduction of water in 0.1 M KOH.

  16. Tunneling magnetic force microscopy

    Science.gov (United States)

    Burke, Edward R.; Gomez, Romel D.; Adly, Amr A.; Mayergoyz, Isaak D.

    1993-01-01

    We have developed a powerful new tool for studying the magnetic patterns on magnetic recording media. This was accomplished by modifying a conventional scanning tunneling microscope. The fine-wire probe that is used to image surface topography was replaced with a flexible magnetic probe. Images obtained with these probes reveal both the surface topography and the magnetic structure. We have made a thorough theoretical analysis of the interaction between the probe and the magnetic fields emanating from a typical recorded surface. Quantitative data about the constituent magnetic fields can then be obtained. We have employed these techniques in studies of two of the most important issues of magnetic record: data overwrite and maximizing data-density. These studies have shown: (1) overwritten data can be retrieved under certain conditions; and (2) improvements in data-density will require new magnetic materials. In the course of these studies we have developed new techniques to analyze magnetic fields of recorded media. These studies are both theoretical and experimental and combined with the use of our magnetic force scanning tunneling microscope should lead to further breakthroughs in the field of magnetic recording.

  17. Scanning Tunneling Microscopy

    Science.gov (United States)

    1992-03-17

    the study of surfact strain. A variety of studies were conducted on Au(in air) CdTe (in air), Hg1-xMnxTe (under glycerin), and Hg 1-xCdx Te (in air...HgCdTe and CdMnTe. (7) Scribing of adjacent parallel lines on the HgCdTe and CdMnTe surfaces. (8) Identification of a new c(4x6) reconstruction on some...tihodoluminescence spectroscopy, coupled with pulsed laser annealing-to reveal systematics between interface chemical and electronic structure. The

  18. Atomic-scale scanning tunneling microscopy study of plasma-oxidized ultrahigh-modulus carbon fiber surfaces.

    Science.gov (United States)

    Paredes, J I; Martínez-Alonso, A; Tascón, J M D

    2003-02-15

    In the present work, scanning tunneling microscopy (STM) was employed to study the surface modification of ultrahigh modulus carbon fibers at the atomic level by oxygen plasma. As detected by STM, the distinctive feature of the fresh, untreated surface was the general presence of atomic-scale arrangements in different degrees of order (from atomic-sized spots without a clearly ordered disposition to triangular patterns identical to those typical of perfect graphite). Following fiber exposure to the plasma, the STM images showed evidence of the abstraction of carbon atoms from random locations on the fiber surface, giving rise to the development of defects (i.e., structural disorder), which in turn were the places where oxygen could be introduced during and after the plasma etching. It was observed that the most effective treatments in terms of extent of surface structural modification (disordering) and uniform introduction of oxygen were those carried out for just a few ( approximately 3) minutes. Considerably shorter exposures failed to provide a homogeneous modification and many locations on the fiber surface remained unaltered, retaining their original atomic-scale order, whereas longer treatments did not bring about further structural changes to the surface and only led to fiber consumption. These results are consistent with previous X-ray photoelectron spectroscopy measurements on these fibers and provide an atomic-level understanding of the saturation effect observed in the surface oxygen concentration of this and other types of carbon fibers with plasma oxidation. Such understanding may also prove helpful for the accurate control and optimization of fiber-matrix interaction in composite materials.

  19. Scanning ultrafast electron microscopy

    OpenAIRE

    Yang, Ding-Shyue; Mohammed, Omar F.; Zewail, Ahmed H.

    2010-01-01

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for whic...

  20. Semiconductor Surface Characterization by Scanning Probe Microscopies

    Science.gov (United States)

    2001-01-01

    potentiometry (STP)8 and ballistic electron emission microscopy (BEEM)9 which allow mapping of lateral surface potential and local subsurface Schottky...A.P.Fein. "Tunneling Spectroscopy of the Si(1 1 1)2xl Surface", Surf.Sci. 181, 295- 306, 1987. 8. P.Muralt, D.W.Pohl, "Scanning tunneling potentiometry

  1. Scanning tunneling microscopy and spectroscopy on GaN and InGaN surfaces; Rastertunnelmikroskopie und -spektroskopie an GaN- und InGaN-Oberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, David

    2009-12-02

    Optelectronic devices based on gallium nitride (GaN) and indium gallium nitride (InGaN) are in the focus of research since more than 20 years and still have great potential for optical applications. In the first part of this work non-polar surfaces of GaN are investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM) and scanning tunneling microscopy (STM). In SEM and AFM, the (1 anti 100)- and especially the (anti 2110)-plane are quite corrugated. For the first time, the (anti 2110)-plane of GaN is atomically resolved in STM. In the second part InGaN quantum dot layers are investigated by X-ray photoelectron spectroscopy (XPS), scanning tunneling spectroscopy (STS) and STM. The STMmeasurements show the dependency of surface morphology on growth conditions in the metalorganic vapour phase epitaxy (MOVPE). Nucleation, a new MOVPE-strategy, is based on phase separations on surfaces. It is shown that locally varying density of states and bandgaps can be detected by STS, that means bandgap histograms and 2D-bandgap-mapping. (orig.)

  2. Scanning Tunneling Spectroscopy of Graphene on Graphite

    OpenAIRE

    Li, Guohong; Luican, Adina; Andrei, Eva Y.

    2008-01-01

    We report low temperature high magnetic field scanning tunneling microscopy and spectroscopy of graphene flakes on graphite that exhibit the structural and electronic properties of graphene decoupled from the substrate. Pronounced peaks in the tunneling spectra develop with field revealing a Landau level sequence that provides a direct way to identify graphene and to determine the degree of its coupling to the substrate. The Fermi velocity and quasiparticle lifetime, obtained from the positio...

  3. Modification by H-termination in growth process of titanium silicide on Si(0 0 1)-2 x 1 observed with scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, T., E-mail: d08gd201@ynu.ac.jp [Faculty of Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501 (Japan); Shudo, K.; Sato, K.; Ohno, S.; Nishioka, H.; Iida, T.; Toramaru, M.; Tanaka, M. [Faculty of Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501 (Japan)

    2009-11-30

    Formation processes of titanium silicide on hydrogen-terminated H/Si(0 0 1)-2 x 1 surface are studied at the atomic scale with a scanning tunneling microscopy (STM). Square-shaped nanoislands were observed on the Ti/H/Si(0 0 1) surface after annealed at 873-1073 K. These are the epitaxial nanoislands moderately grown due to the local orientation relationship between C49-TiSi{sub 2} and Si(0 0 1), because passivation by surface hydrogen on Si(0 0 1) suppresses active and complex bond formation of Ti-Si.

  4. A perfect wetting of Mg monolayer on Ag(111) under atomic scale investigation: First principles calculations, scanning tunneling microscopy, and Auger spectroscopy

    Science.gov (United States)

    Migaou, Amani; Sarpi, Brice; Guiltat, Mathilde; Payen, Kevin; Daineche, Rachid; Landa, Georges; Vizzini, Sébastien; Hémeryck, Anne

    2016-05-01

    First principles calculations, scanning tunneling microscopy, and Auger spectroscopy experiments of the adsorption of Mg on Ag(111) substrate are conducted. This detailed study reveals that an atomic scale controlled deposition of a metallic Mg monolayer perfectly wets the silver substrate without any alloy formation at the interface at room temperature. A liquid-like behavior of the Mg species on the Ag substrate is highlighted as no dot formation is observed when coverage increases. Finally a layer-by-layer growth mode of Mg on Ag(111) can be predicted, thanks to density functional theory calculations as observed experimentally.

  5. Structure determination of the indium induced Si(001)-(4X3) reconstruction by surface x-ray diffraction and scanning tunneling microscopy

    DEFF Research Database (Denmark)

    Bunk, O.; Falkenberg, G.; Seehofer, L.

    1998-01-01

    The indium-induced Si(001)-(4 X 3) reconstruction has been investigated by surface X-ray diffraction (SXRD) measurements with synchrotron radiation and scanning tunneling microscopy (STM). The Patterson function analysis enables us to exclude In dimers as a structural element in this reconstruction....... We present a new structural model which includes 6 In atoms threefold coordinated to Si atoms and 5 displaced Si atoms per unit cell. Relaxations down to the sixth layer were determined. 'Trimers' made up of In-Si-In atoms are a key structural element. (C) 1998 Elsevier Science B.V....

  6. Detecting element specific electrons from a single cobalt nanocluster with synchrotron x-ray scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kersell, Heath; Shirato, Nozomi; Cummings, Marvin; Chang, Hao; Miller, Dean; Rosenmann, Daniel; Hla, Saw-Wai; Rose, Volker

    2017-09-04

    We use a nanofabricated scanning tunneling microscope tip as a detector to investigate local X-ray induced tunneling and electron emission from a single cobalt nanocluster on a Au(111) surface. The tip-detector is positioned a few angstroms above the nanocluster, and ramping the incident X-ray energy across the Co photoabsorption K-edge enables the detection of element specific electrons. Atomic-scale spatial dependent changes in the X-ray absorption cross section are directly measured by taking the X-ray induced current as a function of X-ray energy. From the measured sample and tip currents, element specific X-ray induced current components can be separated and thereby the corresponding yields for the X-ray induced processes of the single cobalt nanocluster can be determined. The detection of element specific synchrotron X-ray induced electrons of a single nanocluster opens a new avenue for materials characterization on a one particle at-a-time basis.

  7. Investigation of Supramolecular Coordination Self-Assembly and Polymerization Confined on Metal Surfaces Using Scanning Tunneling Microscopy

    Science.gov (United States)

    Lin, Tao

    Organic molecules are envisioned as the building blocks for design and fabrication of functional devices in future, owing to their versatility, low cost and flexibility. Although some devices such as organic light-emitting diode (OLED) have been already applied in our daily lives, the field is still in its infancy and numerous challenges still remain. In particular, fundamental understanding of the process of organic material fabrication at a molecular level is highly desirable. This thesis focuses on the design and fabrication of supramolecular and macromolecular nanostructures on a Au(111) surface through self-assembly, polymerization and a combination of two. We used scanning tunneling microscopy (STM) as an experimental tool and Monte Carlo (MC) and kinetic Monte Carlo (KMC) simulations as theoretical tools to characterize the structures of these systems and to investigate the mechanisms of the self-assembly and polymerization processes at a single-molecular level. The results of this thesis consist of four parts as below: Part I addresses the mechanisms of two-dimensional multicomponent supramolecular self-assembly via pyridyl-Fe-terpyridyl coordination. Firstly, we studied four types of self-assembled metal-organic systems exhibiting different dimensionalities using specifically-designed molecular building blocks. We found that the two-dimensional system is under thermodynamic controls while the systems of lower dimension are under kinetic controls. Secondly, we studied the self-assembly of a series of cyclic supramolecular polygons. Our results indicate that the yield of on-surface cyclic polygon structures is very low independent of temperature and concentration and this phenomenon can be attributed to a subtle competition between kinetic and thermodynamic controls. These results shed light on thermodynamic and kinetic controls in on-surface coordination self-assembly. Part II addresses the two-dimensional supramolecular self-assembly of porphyrin

  8. Scanning ultrafast electron microscopy.

    Science.gov (United States)

    Yang, Ding-Shyue; Mohammed, Omar F; Zewail, Ahmed H

    2010-08-24

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability.

  9. Investigation of the structural anisotropy in a self-assembling glycinate layer on Cu(100) by scanning tunneling microscopy and density functional theory calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmin, Mikhail [Surface Science Laboratory, Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere (Finland); Ioffe Physical Technical Institute, Russian Academy of Sciences, 26 Polytekhnicheskaya, St Petersburg 194021 (Russian Federation); Lahtonen, Kimmo; Vuori, Leena [Surface Science Laboratory, Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere (Finland); Sánchez-de-Armas, Rocío [Materials Theory Division, Department of Physics and Astronomy, Uppsala University, P.O. Box 516, S75120 Uppsala (Sweden); Hirsimäki, Mika, E-mail: mikahirsi@gmail.com [Surface Science Laboratory, Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere (Finland); Valden, Mika [Surface Science Laboratory, Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere (Finland)

    2017-07-01

    Highlights: • Deprotonation reaction of glycine and self-assembly of glycinate is observed on Cu. • Bias-dependent scanning tunneling microscopy indicates two glycinate geometries. • Density functional theory calculations confirm the two non-identical configurations. • Non-identical adsorption explains the anisotropy in adlayer’s electronic structure. - Abstract: Self-assembling organic molecule-metal interfaces exhibiting free-electron like (FEL) states offers an attractive bottom-up approach to fabricating materials for molecular electronics. Accomplishing this, however, requires detailed understanding of the fundamental driving mechanisms behind the self-assembly process. For instance, it is still unresolved as to why the adsorption of glycine ([NH{sub 2}(CH{sub 2})COOH]) on isotropic Cu(100) single crystal surface leads, via deprotonation and self-assembly, to a glycinate ([NH{sub 2}(CH{sub 2})COO–]) layer that exhibits anisotropic FEL behavior. Here, we report on bias-dependent scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations for glycine adsorption on Cu(100) single crystal surface. We find that after physical vapor deposition (PVD) of glycine on Cu(100), glycinate self-assembles into an overlayer exhibiting c(2 × 4) and p(2 × 4) symmetries with non-identical adsorption sites. Our findings underscore the intricacy of electrical conductivity in nanomolecular organic overlayers and the critical role the structural anisotropy at molecule-metal interface plays in the fabrication of materials for molecular electronics.

  10. Investigation of atomic species in Pt-induced nanowires on Ge(001) surface by combined atomic force and scanning tunneling microscopy

    Science.gov (United States)

    Inami, Eiichi; Sugimoto, Yoshiaki; Shinozaki, Takuya; Gurlu, Oguzhan; Yurtsever, Ayhan

    2017-10-01

    We have studied identification of atomic species in Pt-induced nanowires self-assembled on the Ge(001) surface by combining scanning tunneling microscopy (STM) and atomic force microscopy (AFM). A small number of Sn atoms substituted in the top atomic chains were utilized as references to identify the target atomic species. Force spectroscopy data taken above single atoms on the Sn-substituted nanowires showed that the ratio between the maximum attractive forces above the Sn and the pristine chain atoms exhibited a constant value of 0.86. The obtained ratio was identical to that between Sn and Ge atoms, strongly suggestive that the top ridge of the Pt-induced nanowire was composed of Ge dimers. Our findings also demonstrate that AFM chemical identification method can be used to identify the unknown atomic species on surfaces, regardless of the homogeneity in the atomic composition, which has not been addressed so far.

  11. A scanning tunneling microscopy study of self-assembled nickel(II) octaethylporphyrin deposited from solutions on HOPG.

    Science.gov (United States)

    Ogunrinde, Ayowale; Hipps, K W; Scudiero, L

    2006-06-20

    The adsorption of nickel(II) octaethylporphyrin (NiOEP) from benzene and chloroform solutions on highly ordered pyrolytic graphite (HOPG) was investigated with a scanning tunneling microscope (STM) operated in ambient conditions. STM images show that NiOEP self-assembles on the graphite surface and that the molecules lie flat and form 2D lattices with spacings of 1.58 +/- 0.03 nm by 1.46 +/- 0.06 nm with a lattice angle of 69 degrees +/- 4 degrees averaged over both solvents. We were unable to eliminate the possibility that one unit cell distance is twice the above-reported distance. The corresponding molecular packing density, 4.5 +/- 0.3 x 10(13) molecules/cm(2), was essentially the same for benzene and chloroform solution deposition. These results differ somewhat from the structure revealed by high-resolution STM images of NiOEP on Au (111). The lack of apparent height (image intensity) in the constant current STM image of the alkane region of alkane-substituted metal porphyrins is attributed to a combination of changes in alkane configuration relative to the ring and associated changes in electronic coupling with HOMO and LUMO.

  12. Single vacancy defect spectroscopy on HfO2 using random telegraph noise signals from scanning tunneling microscopy

    Science.gov (United States)

    Thamankar, R.; Raghavan, N.; Molina, J.; Puglisi, F. M.; O'Shea, S. J.; Shubhakar, K.; Larcher, L.; Pavan, P.; Padovani, A.; Pey, K. L.

    2016-02-01

    Random telegraph noise (RTN) measurements are typically carried out at the device level using standard probe station based electrical characterization setup, where the measured current represents a cumulative effect of the simultaneous response of electron capture/emission events at multiple oxygen vacancy defect (trap) sites. To better characterize the individual defects in the high-κ dielectric thin film, we propose and demonstrate here the measurement and analysis of RTN at the nanoscale using a room temperature scanning tunneling microscope setup, with an effective area of interaction of the probe tip that is as small as 10 nm in diameter. Two-level and multi-level RTN signals due to single and multiple defect locations (possibly dispersed in space and energy) are observed on 4 nm HfO2 thin films deposited on n-Si (100) substrate. The RTN signals are statistically analyzed using the Factorial Hidden Markov Model technique to decode the noise contribution of more than one defect (if any) and estimate the statistical parameters of each RTN signal (i.e., amplitude of fluctuation, capture and emission time constants). Observation of RTN at the nanoscale presents a new opportunity for studies on defect chemistry, single-defect kinetics and their stochastics in thin film dielectric materials. This method allows us to characterize the fast traps with time constants ranging in the millisecond to tens of seconds range.

  13. Scanning tunneling spectroscopy of graphene on graphite.

    Science.gov (United States)

    Li, Guohong; Luican, Adina; Andrei, Eva Y

    2009-05-01

    We report low temperature high magnetic field scanning tunneling microscopy and spectroscopy of graphene flakes on graphite that exhibit the structural and electronic properties of graphene decoupled from the substrate. Pronounced peaks in the tunneling spectra develop with increasing field revealing a Landau level sequence that provides a direct way to identify graphene and to determine the degree of its coupling to the substrate. The Fermi velocity and quasiparticle lifetime, obtained from the positions and width of the peaks, provide access to the electron-phonon and electron-electron interactions.

  14. Structure, Mobility, and Composition of Transition Metal Catalyst Surfaces. High-Pressure Scanning Tunneling Microscopy and Ambient-Pressure X-ray Photoelectron Spectroscopy Studies

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhongwei [Univ. of California, Berkeley, CA (United States)

    2013-12-06

    Surface structure, mobility, and composition of transition metal catalysts were studied by high-pressure scanning tunneling microscopy (HP-STM) and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) at high gas pressures. HP-STM makes it possible to determine the atomic or molecular rearrangement at catalyst surfaces, particularly at the low-coordinated active surface sites. AP-XPS monitors changes in elemental composition and chemical states of catalysts in response to variations in gas environments. Stepped Pt and Cu single crystals, the hexagonally reconstructed Pt(100) single crystal, and Pt-based bimetallic nanoparticles with controlled size, shape and composition, were employed as the model catalysts for experiments in this thesis.

  15. Characterizing low-coordinated atoms at the periphery of MgO-supported Au islands using scanning tunneling microscopy and electronic structure calculations

    Science.gov (United States)

    Lin, Xiao; Nilius, Niklas; Sterrer, Martin; Koskinen, Pekka; Häkkinen, Hannu; Freund, Hans-Joachim

    2010-04-01

    The perimeter of oxide-supported metal particles is suggested to be of pivotal importance for various catalytic processes. To elucidate the underlying effects, the electronic properties of edge and corner atoms of planar Au clusters on MgO/Ag(001) thin films have been analyzed with scanning tunneling microscopy and electronic structure calculations. The low-coordinated perimeter atoms are characterized by a high density of s -derived states at the Fermi level. Those states accommodate transfer electrons from the MgO/Ag substrate, which render the perimeter atoms negatively charged. In contrast, the inner atoms of the island are not affected by the charge transfer and remain neutral. This combination of charge accumulation and high state-density explains the specific relevance of the cluster perimeter in adsorption and reaction processes.

  16. DESORPTION OF Te CAPPING LAYER FROM ZnTe (100: AUGER SPECTROSCOPY, LOW-ENERGY ELECTRON DIFFRACTION AND SCANNING TUNNELING MICROSCOPY

    Directory of Open Access Journals (Sweden)

    K. K. Sossoe

    2016-01-01

    Full Text Available The influence of the annealing temperature to desorb a protective Te capping layer of the zinc telluride (ZnTe (100 surface was investigated. The surface reconstruction of the ZnTe (100 upon the removal of a Te capping layer grown by the molecular beam epitaxy was characterized by different methods. Auger spectroscopy brought out the chemical composition of the surface before and after annealing; the Low-energy electron diffraction (LEED gave information about the crystallographic structure. The surface crystallographic configurations of tellurium Te (c (2x2 and Te (c (2x1 are confirmed by scanning tunneling microscopy (STM. Such a study reveals a phase transition from a rich-Te to a poor-Te surface as the annealing temperature increases. 

  17. Recovery and local-variation of Dirac cones in oxygen-intercalated graphene on Ru(0001) studied using scanning tunneling microscopy and spectroscopy.

    Science.gov (United States)

    Jang, Won-Jun; Kim, Howon; Jeon, Jeong Heum; Yoon, Jong Keon; Kahng, Se-Jong

    2013-10-14

    Methods to decouple epitaxial graphene from metal substrates have been extensively studied, with anticipation of observing unperturbed Dirac cone properties, but its local electronic structures were rarely studied. Here, we investigated the local variations of Dirac cones recovered using oxygen intercalation applied to epitaxial graphene on Ru(0001) using scanning tunneling microscopy and spectroscopy (STM and STS). New V-shaped features, which appear in the STS data at the oxygen-intercalated graphene regions, are attributed to the signatures of recovered Dirac cones. The Dirac point energy was observed at 0.48 eV below the Fermi level, different from previous photoemission results because of different oxygen coverages. The observed spatial variations of Dirac point energy were explained by the weakly protruding network structures caused by a small net strain in graphene. Our study shows that oxygen-intercalated graphene provides an excellent platform for further graphene research at the nano-meter scale with unperturbed Dirac cones.

  18. Voltammetry and single-molecule in situ scanning tunneling microscopy of laccases and bilirubin oxidase in electrocatalytic dioxygen reduction on Au(111) single-crystal electrodes

    DEFF Research Database (Denmark)

    Climent, Victor; Zhang, Jingdong; Friis, Esben Peter

    2012-01-01

    to elucidate the catalytic mechanism, where laccase (sub)monolayer voltammetry has been a core approach. In this report, we address voltammetry and electrocatalysis of O2 reduction of (sub)monolayers of several laccases in new ways. These are based on the use of single-crystal, atomically planar bare Au(111......)-electrode surfaces or surfaces modified by thiol-based self-assembled molecular monolayers. These well-defined surfaces enable introducing electrochemical scanning tunneling microscopy directly in aqueous biological media in which the enzymes are operative (in situ STM), to the level of resolution...... of the single enzyme molecule in electrocatalytic action. Enzyme-electrode electronic contact and intramolecular electron transfer triggered by the electrode potential or by O2-substrate binding to the enzyme, followed at the single-molecule level, are the most important observations of this study. © 2011...

  19. Observation of Supermodulation in LaO0.5F0.5BiSe2 by Scanning Tunneling Microscopy and Spectroscopy

    Science.gov (United States)

    Demura, Satoshi; Ishida, Naoki; Fujisawa, Yuita; Sakata, Hideaki

    2017-11-01

    We observed the surface and electronic structure of single-crystal LaO0.5F0.5BiSe2 by scanning tunneling microscopy/spectroscopy at 4.2 K. A square lattice composed of Bi atoms was observed at a positive sample bias voltage for the surface prepared by cleavage. At a negative sample bias voltage, a stripe structure along the Bi-Bi directions was observed as in a previous report on NdO0.7F0.3BiS2. Furthermore, we observed a supermodulation along the diagonal directions with a period of about five times the lattice constant. This seems to be indicative of the structural instability of this system rather than the electronic instability attributed to a nesting picture.

  20. Light-modulated scanning tunneling microscopy studied on photoinduced carrier generations at PbI2/perovskite interface of perovskite solar cells

    Science.gov (United States)

    Chiu, Ya-Ping; Shih, Min-Chuan; Li, Shao-Sian; Hsieh, Cheng-Hua; Wang, Ying-Chiao; Yang, Hung-Duen; Chang, Chia-Seng; Chen, Chun-Wei

    Perovskite solar devices based on CH3NH3PbX3 (X = Cl, Br, I) have recently shown tremendous efficiency enhancements up to 20% in photovoltaic applications. The presence of PbI2 in perovskite films has been found to affect the charge carrier transport behaviors and device performance of perovskite solar cells. In this work, we employed the unique ability of light-modulated scanning tunneling microscopy (LM-STM) technique to dircetly reveal the correlation of the nanoscaled compositional distributions and photo-induced interfacial electronic structures at the PbI2/perovskite interface of perovskite grains under light illumination. The result reveals the important role of the optimum PbI2 passivation layers (a thickness less than 20 nm) on the charge separation and recombination at perovskite crystal grains. The unique LM-STM technique demonstartes great potential for application in the future exploring photovoltaic systems.

  1. Iron on GaN(0001) pseudo-1 × 1 (1+1/(12) ) investigated by scanning tunneling microscopy and first-principles theory

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wenzhi; Mandru, Andrada-Oana; Smith, Arthur R., E-mail: smitha2@ohio.edu [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Takeuchi, Noboru [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico Apartado Postal 14, Ensenada Baja California, Codigo Postal 22800 (Mexico); Al-Brithen, Hamad A. H. [Physics and Astronomy Department, King Abdulah Institute for Nanotechnology, King Saud University, Riyadh, Saudi Arabia, and National Center for Nano Technology, KACST, Riyadh (Saudi Arabia)

    2014-04-28

    We have investigated sub-monolayer iron deposition on atomically smooth GaN(0001) pseudo-1 × 1 (1+1/(12) ). The iron is deposited at a substrate temperature of 360 °C, upon which reflection high energy electron diffraction shows a transformation to a √(3)×√(3)-R30° pattern. After cooling to room temperature, the pattern transforms to a 6 × 6, and scanning tunneling microscopy reveals 6 × 6 reconstructed regions decorating the GaN step edges. First-principles theoretical calculations have been carried out for a range of possible structural models, one of the best being a Ga dimer model consisting of 2/9 monolayer of Fe incorporated into 7/3 monolayer of Ga in a relaxed but distorted structure.

  2. Adsorption characteristics of Er3N@C80on W(110 and Au(111 studied via scanning tunneling microscopy and spectroscopy

    Directory of Open Access Journals (Sweden)

    Sebastian Schimmel

    2017-05-01

    Full Text Available We performed a study on the fundamental adsorption characteristics of Er3N@C80 deposited on W(110 and Au(111 via room temperature scanning tunneling microscopy and spectroscopy. Adsorbed on W(110, a comparatively strong bond to the endohedral fullerenes inhibited the formation of ordered monolayer islands. In contrast, the Au(111-surface provides a sufficiently high mobility for the molecules to arrange in monolayer islands after annealing. Interestingly, the fullerenes modify the herringbone reconstruction indicating that the molecule–substrate interaction is of considerable extent. Investigations concerning the electronic structure of Er3N@C80/Au(111 reveals spatial variations dependent on the termination of the Au(111 at the interface.

  3. Scanning Probe Microscopy of Graphene

    Science.gov (United States)

    Tautz, Pamela

    2011-10-01

    Scanning tunneling microscopy has been used to study the unusual electronic properties of graphene. In an effort to support the graphene with minimal interaction with the substrate, we used a hexagonal boron nitride (hBN) substrate. To minimize contaminants between the CVD graphene and boron nitride, the graphene samples were cleaned with distilled water and isopropanol prior to transfer to hBN substrate. We have also examined the growth of graphene flakes by chemical vapor deposition. In particular, we examined the relationship between the orientations of the first and second layer of CVD grown graphene. We found the growth mechanism preferentially resulted in rotations of 9^o or less indicating flakes with first and second layers aligned.

  4. High Pressure Scanning Tunneling Microscopy Studies of AdsorbateStructure and Mobility during Catalytic Reactions: Novel Design of anUltra High Pressure, High Temperature Scanning Tunneling MicroscopeSystem for Probing Catalytic Conversions

    Energy Technology Data Exchange (ETDEWEB)

    Tang, David Chi-Wai [Univ. of California, Berkeley, CA (United States)

    2005-05-16

    The aim of the work presented therein is to take advantage of scanning tunneling microscope’s (STM) capability for operation under a variety of environments under real time and at atomic resolution to monitor adsorbate structures and mobility under high pressures, as well as to design a new generation of STM systems that allow imaging in situ at both higher pressures (35 atm) and temperatures (350 °C).

  5. Seismic scanning tunneling macroscope - Theory

    KAUST Repository

    Schuster, Gerard T.

    2012-09-01

    We propose a seismic scanning tunneling macroscope (SSTM) that can detect the presence of sub-wavelength scatterers in the near-field of either the source or the receivers. Analytic formulas for the time reverse mirror (TRM) profile associated with a single scatterer model show that the spatial resolution limit to be, unlike the Abbe limit of λ/2, independent of wavelength and linearly proportional to the source-scatterer separation as long as the point scatterer is in the near-field region; if the sub-wavelength scatterer is a spherical impedance discontinuity then the resolution will also be limited by the radius of the sphere. Therefore, superresolution imaging can be achieved as the scatterer approaches the source. This is analogous to an optical scanning tunneling microscope that has sub-wavelength resolution. Scaled to seismic frequencies, it is theoretically possible to extract 100 Hz information from 20 Hz data by imaging of near-field seismic energy.

  6. Toward quantitative STM: Scanning tunneling microscopy study of structure and dynamics of adsorbates on transition metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Dunphy, James Christopher [Univ. of California, Berkeley, CA (United States)

    1995-05-01

    STM was applied to chemisorbed S layers on Re(000l) and Mo(100) surfaces. As function of coverage on both these surfaces, S orders into several different overlayer structures, which have been studied by dynamic LEED. STM images of all these structures were obtained. Approximate location of S atoms in the structures was determined by inspecting the images, especially the regions containing defects. Results are in agreement with LEED except for the p(2xl) overlayer of sulfur on Mo(100). The STM images were compared to calculations made with Electron Scattering Quantum Chemistry (ESQC) theory. Variation of contrast in experimental images is explained as a result of changes in STM tip termination structure. STM image contrast is a result of changes in the interference between different paths for the tunneling electrons. The simplest structure on the Mo(100) surface was used as a model for developing and testing a method of quantitative structure determination with the STM. Experimental STM images acquired under a range of tunneling conditions were compared to theoretical calculations of the images as a function of surface structure to determine the structure which best fit. Results matched within approximately 0.1 Angstroms a LEED structural determination. At lower S coverage, diffusion of S atoms over the Re(0001) surface and the lateral interaction between these atoms were investigated by application of a new image analysis technique. The interaction between the S and a coadsorbed CO layer was also studied, and CO was found to induce compression of the S overlayer. A similar result was found for Au deposited on the sulfur covered Mo(100) surface. The interaction between steps on the Mo surface was found to be influenced by S adsorption and this observation was interpreted with the theory of equilibrium crystal shape. Design of an STM instrument which operates at cryogenic and variable sample temperatures, and its future applications, are described.

  7. A unifying model for non-adiabatic coupling at metallic surfaces beyond the local harmonic approximation: from vibrational relaxation to scanning tunneling microscopy.

    Science.gov (United States)

    Tremblay, Jean Christophe

    2013-06-28

    A model for treating excitation and relaxation of adsorbates at metallic surfaces induced by non-adiabatic coupling is developed. The derivation is based on the concept of resonant electron transfer, where the adsorbate serves as a molecular bridge for the inelastic transition between an electron source and a sink. In this picture, energy relaxation and scanning tunneling microscopy (STM) at metallic surfaces are treated on an equal footing as a quasi-thermal process. The model goes beyond the local harmonic approximation and allows for an unbiased description of floppy systems with multiple potential wells. Further, the limitation of the product ansatz for the vibronic wave function to include the position-dependence of the non-adiabatic couplings is avoided by explicitly enforcing detailed balance. The theory is applied to the excitation of hydrogen on palladium, which has multiple local potential minima connected by low energy barriers. The main aspects investigated are the lifetimes of adsorbate vibrations in different adsorption sites, as well as the dependence of the excitation, response, and transfer rates on an applied potential bias. The excitation and relaxation simulations reveal intricate population dynamics that depart significantly from the simplistic tunneling model in a truncated harmonic potential. In particular, the population decay from an initially occupied local minimum induced by the contact with an STM tip is found to be better described by a double exponential. The two rates are interpreted as a response to the system perturbation and a transfer rate following the perturbation. The transfer rate is found to obey a power law, as was the case in previous experimental and theoretical work.

  8. Attempts to test an alternative electrodynamic theory of superconductors by low-temperature scanning tunneling and atomic force microscopy

    Science.gov (United States)

    Peronio, Angelo; Giessibl, Franz J.

    2016-09-01

    We perform an experiment to test between two theories of the electrodynamics of superconductors: the standard London theory and an alternative proposed by J. E. Hirsch [Phys. Rev. B 69, 214515 (2004), 10.1103/PhysRevB.69.214515]. The two alternatives give different predictions with respect to the screening of an electric field by a superconductor, and we try to detect this effect using atomic force microscopy on a niobium sample. We also perform the reverse experiment, where we demonstrate a superconductive tip mounted on a qPlus force sensor. Due to limited accuracy, we are able neither to prove nor to disprove Hirsch's hypothesis. Within our accuracy of 0.17 N/m, the superconductive transition does not alter the atomic-scale interaction between tip and sample.

  9. Mn Doping Effects on the Electronic Band Structure of PbS Quantum Dot Thin Films: A Scanning Tunneling Microscopy Analysis

    Science.gov (United States)

    Yost, Andrew J.; Rimal, Gaurab; Tang, Jinke; Chien, Teyu

    A thorough understanding of the phenomena associated with doping of transition metals in semiconductors is important for the development of semiconducting electronic technologies such as semiconducting quantum dot sensitized solar cells (QDSSC). Manganese doping is of particular interest in a PbS QD as it is potentially capable of increasing overall QDSSC performance. Here we present scanning tunneling microscopy and spectroscopy studies about the effects of Manganese doping on the energy band structures of PbS semiconducting QD thin films, grown using pulsed laser deposition. As a result of Manganese doping in the PbS QD thin films, a widening of the electronic band gap was observed, which is responsible for the observed increase in resistivity. Furthermore, a loss of long range periodicity observed by XRD, upon incorporation of Manganese, indicates that the Manganese dopants also induce a large amount of grain boundaries. This work was supported by the following: U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering, DEFG02-10ER46728 and the National Science Foundation Grant #0948027.

  10. A Scanning Tunnelling Microscopy Study on an Alloyed Topological Insulator, Bi1.5Sb0.5Te1.7Se1.3

    Science.gov (United States)

    Ko, Wonhee; Jeon, Insu; Kim, Hyo Won; Kwon, Hyeokshin; Oh, Youngtek; Kahng, Se-Jong; Park, Joonbum; Kim, Jun Sung; Hwang, Sung Woo; Suh, Hwansoo

    2015-03-01

    Efficient doping of topological insulators while protecting its topological nature is key ingredient to realize topological devices. Engineering the chemical potential in the alloyed compound Bi2-xSbxTe3-ySey has been achieved by tuning its chemical composition. However, the effect of alloying in microscopic scale has not yet been fully investigated with local probes. Here we report on the atomic and electronic structures of Bi1.5Sb0.5Te1.7Se1.3 studied using scanning tunnelling microscopy/spectroscopy (STM/STS). Although there is significant surface disorder due to the alloying of constituent atoms, cleaved surfaces of the crystals present a well-ordered hexagonal lattice in STM topographs with 1 nm high quintuple layer steps. STS results reflect the band structure and indicate that the surface state and Fermi energy are both located inside the energy gap. The surface states do not show any electron back-scattering; due to their topological nature they are extremely robust. Landau levels generated by perpendicular magnetic field follow the massless Dirac fermions. This finding demonstrates that alloying is a promising route for efficient doping of topological insulators whilst keeping the topological surface state intact.

  11. Laser-Combined Scanning Tunneling Microscopy on the Carrier Dynamics in Low-Temperature-Grown GaAs/AlGaAs/GaAs

    Directory of Open Access Journals (Sweden)

    Yasuhiko Terada

    2011-01-01

    Full Text Available We investigated carrier recombination dynamics in a low-temperature-grown GaAs (LT-GaAs/AlGaAs/GaAs heterostructure by laser-combined scanning tunneling microscopy, shaken-pulse-pair-excited STM (SPPX-STM. With the AlGaAs interlayer as a barrier against the flow of photocarriers, recombination lifetimes in LT-GaAs of 4.0 ps and GaAs of 4.8 ns were successfully observed separately. We directly demonstrated the high temporal resolution of SPPX-STM by showing the recombination lifetime of carriers in LT-GaAs (4.0 ps in the range of subpicosecond temporal resolution. In the carrier-lifetime-mapping measurement, a blurring of recombination lifetime up to 50 nm was observed at the LT-GaAs/AlGaAs boundary, which was discussed in consideration of the screening length of the electric field from the STM probe. The effect of the built-in potential on the signal, caused by the existence of LT-GaAs/AlGaAs/GaAs boundaries, was discussed in detail.

  12. Ultra-high vacuum scanning tunnelling microscopy investigation of free radical adsorption to the Si(111)-7 x 7 surface

    Energy Technology Data Exchange (ETDEWEB)

    Guisinger, Nathan P; Elder, Shaun P; Yoder, Nathan L; Hersam, Mark C [Materials Science and Engineering Department, Northwestern University, 2220 Campus Drive, Evanston, IL 60208-3108 (United States)

    2007-01-31

    Room-temperature ultra-high vacuum (UHV) scanning tunnelling microscopy (STM) has been employed to investigate free radical chemistry on the Si(111)-7 x 7 surface with atomic-scale spatial resolution. In particular, due to its single-site binding mechanism and extensive previous study on the Si(100)-2 x 1 surface, the nitroxyl free radical 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) was explored. UHV STM imaging of isolated molecules revealed that TEMPO covalently reacts with adatom dangling bonds with high affinity. By monitoring TEMPO adsorption as a function of surface coverage, TEMPO was also found to preferentially bind to centre adatom sites at the initial stages of adsorption. On the other hand, as the surface coverage increased, TEMPO molecules adsorbed to centre adatoms and corner adatoms approached a ratio of 1:1. At all surface coverage levels, TEMPO showed minimal preference for binding to either the faulted or unfaulted half of the unit cell. Consequently, upon saturation, the TEMPO adlayer exhibited long-range ordering and preserved the underlying 7 x 7 surface reconstruction. This study provides fundamental insight into free radical surface chemistry and suggests a direct pathway for forming nearly perfectly ordered organic adlayers on the Si(111)-7 x 7 surface.

  13. Spatially Resolved Imaging on Photocarrier Generations and Band Alignments at Perovskite/PbI2 Heterointerfaces of Perovskite Solar Cells by Light-Modulated Scanning Tunneling Microscopy.

    Science.gov (United States)

    Shih, Min-Chuan; Li, Shao-Sian; Hsieh, Cheng-Hua; Wang, Ying-Chiao; Yang, Hung-Duen; Chiu, Ya-Ping; Chang, Chia-Seng; Chen, Chun-Wei

    2017-02-08

    The presence of the PbI2 passivation layers at perovskite crystal grains has been found to considerably affect the charge carrier transport behaviors and device performance of perovskite solar cells. This work demonstrates the application of a novel light-modulated scanning tunneling microscopy (LM-STM) technique to reveal the interfacial electronic structures at the heterointerfaces between CH3NH3PbI3 perovskite crystals and PbI2 passivation layers of individual perovskite grains under light illumination. Most importantly, this technique enabled the first observation of spatially resolved mapping images of photoinduced interfacial band bending of valence bands and conduction bands and the photogenerated electron and hole carriers at the heterointerfaces of perovskite crystal grains. By systematically exploring the interfacial electronic structures of individual perovskite grains, enhanced charge separation and reduced back recombination were observed when an optimal design of interfacial PbI2 passivation layers consisting of a thickness less than 20 nm at perovskite crystal grains was applied.

  14. Scanning tunneling microscopy and density functional theory investigations on molecular self-assembly of graphene on Ru(0 0 0 1)

    Science.gov (United States)

    Song, Junjie; Zhang, Han-jie; Zhang, Yuxi; Cai, Yiliang; Bao, Shining; He, Pimo

    2016-03-01

    Investigations on the bottom-up fabrication of graphene with 1,3,5-triphenylbenzene as precursor on Ru(0 0 0 1) was carried out using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. Upon annealing 1,3,5-triphenylbenzene overlayer on Ru(0 0 0 1) at 550 °C, the precursors dehydrogenated and coalesced into graphitized flakes, and subsequent annealing up to 600 °C results in complete graphene conversion. The migration behavior and close-packing morphology of precursors were captured during STM measurements, and DFT calculations indicated that the inter-molecular interaction is responsible for the accumulation and close-packing of the precursors. The noticeable increment in the dehydrogenation barrier from 1.27 eV for monomer adsorption to 1.62 eV for dimer adsorption is well consistent with the observed drastic reduction of the graphitization temperature at lower precursor coverage, suggesting the crucial influence of inter-molecular vdW interaction on the dehydrogenation process.

  15. Atomistic study of comblike structure on the MoO2/Mo(110) surface by scanning tunneling microscopy and density functional theory calculations

    Science.gov (United States)

    Okada, Arifumi; Hara, Shinsuke; Yoshimura, Masamichi

    2017-09-01

    The origin of comblike step formation, which was previously observed in the initial oxidation stage of the Mo(110) surface, was investigated by comparing between scanning tunneling microscopy (STM) observations and ab initio density functional theory (DFT) calculations. The comblike steps were obtained by the formation and evaporation of cluster arrays during oxidation and thermal treatment. On the terraces surrounding the comblike steps formed by the evaporation of clusters, a characteristic “overstripe” pattern was found. On the basis of this pattern, it is assumed that a reliable unit cell with MoO2(010) placed on Mo(110) with in-plane rotation can be constructed and ab initio structural relaxations can be performed. The calculations included “small” model calculations for investigating stable interfacial oxygen sites and “large” model calculations for simulating STM images, and calculation results were compared with experimental results. The simulated STM images show good agreement with the experimental observations, indicating the relevance of the large model. From these analyses, it is pointed out that the local stresses on molybdenum in the oxide layer were important for the comblike step formation.

  16. Confocal scanning microscopy

    DEFF Research Database (Denmark)

    Bariani, Paolo

    This report is based on a metrological investigation on confocal microscopy technique carried out by Uffe Rolf Arlø Theilade and Paolo Bariani. The purpose of the experimental activity was twofold a metrological instrument characterization and application to assessment of rough PP injection moulded...... replicated topography. Confocal microscopy is seen to be a promising technique in metrology of microstructures. Some limitations with respect to surface metrology were found during the experiments. The experiments were carried out using a Zeiss LSM 5 Pascal microscope owned by the Danish Polymer Centre...

  17. Scanned probe microscopy for thin film superconductor development

    Energy Technology Data Exchange (ETDEWEB)

    Moreland, J. [National Institute of Standards and Technology, Boulder, CO (United States)

    1996-12-31

    Scanned probe microscopy is a general term encompassing the science of imaging based on piezoelectric driven probes for measuring local changes in nanoscale properties of materials and devices. Techniques like scanning tunneling microscopy, atomic force microscopy, and scanning potentiometry are becoming common tools in the production and development labs in the semiconductor industry. The author presents several examples of applications specific to the development of high temperature superconducting thin films and thin-film devices.

  18. Low Temperature Scanning Tunneling Spectroscopy

    Science.gov (United States)

    Kirk, Michael Dominic

    A scanning tunneling microscope (STM) was designed and built to operate at liquid helium temperature and was used to measure highly localized electron tunneling spectroscopy. Several instruments were built, all capable of operating in many different environments: air, vacuum, liquid helium and in a transfer gas. An adaptation of one particular design was made into an atomic force microscope capable of operating at low temperatures. Using a low temperature STM, three adsorbed molecular species (liquid crystals, sorbic acid, and carbon monoxide), deposited on a graphite substrate, have been imaged at 4.2K. The inelastic tunneling spectra of these adsorbates show strong peaks in dI/dV vs V curves at energies that correspond to known vibrational modes. The increase in conductance at the onset of inelastic tunneling was measured to be as high as 100 times. The spatial variation of the spectra was measured and was seen to change dramatically on the scale of angstroms, suggesting that individual molecular bonds could be measured. A theoretical model is presented to explain the contrast seen in the STM images of adsorbed molecules, thereby explaining why adsorbed molecules appear to be more conductive than the background. The microscope proved very useful for measuring the energy gap of high temperature superconductors. These materials often have submicron grain sizes. For LaSrCuO, YBaCuO, and BiCaSrCuO, the conductance curves showed a large energy gap suggesting a strongly coupled superconductor. The conductance curves also indicated that intergrain tunneling may occur and that the background conductance varied linearly with the applied voltage. The crystalline structure of rm Bi_2 Sr_2 CaCu_2 O_ {8 + delta} was imaged by an STM operating in air and in ultra-high vacuum. From the STM images the bulk crystal structure model for this material was refined. Finally, the STM was used to make holes reproducibly on a graphite surface with diameters less than 40A. Because the

  19. Formation and structure of p-nitrobenzoic acid adlayer on Au(111) surface in HClO4 investigated by in-situ scanning tunneling microscopy.

    Science.gov (United States)

    Yang, Liu; Chen, Ting; Wang, Dong; Wan, Li-Jun

    2011-06-01

    The adsorption and adlayer structure of p-nitrobenzoic acid (pNBA) on a Au(111) surface in 0.1 M HCIO4 are investigated by in-situ scanning tunneling microscopy (STM) and cyclic voltammetry. The pNBA adlayer is prepared by dipping Au(111) into a saturated pNBA aqueous solution. The cyclic voltammogram (CV) of the so-prepared Au(111) electrode shows an irreversible cathodic peak at 0.24 V, which corresponds to the electro-reduction reaction from pNBA to hydroxylamine, and a pair of reversible peaks at ca. 0.7 V, corresponding to redox reaction of hydroxylamine to nitrosobenzoic acid. STM is employed to investigate the pNBA adlayer structure. The molecules form ordered adlayers in (16 x 2 square root of 3), (7 x 4 square root of 3) and (9 x 6 square root of 3) structures at the double layer potential region. High resolution STM image reveals the details of the molecular arrangement in the adlayers. On the basis of the STM image and the chemical structure of pNBA, structural models for three adlayers are proposed. In all three structures, pNBA molecules adsorb perpendicularly with the carboxylic groups contacting with the Au(111) substrate. The effect of dipping time on the adlayer formation is investigated. Upon shifting the electrode potentials in negative direction to induce the electroreduction reaction, the bright dots corresponding to the molecular aggregations start emerging on the surface and selectively locate at the elbow position along Au(111) reconstruction lines. The results provide direct evidence for the adsorption and electrochemical behavior of nitro-benzene derivatives.

  20. Scanning Tunneling Microscopy Studies of Charge Density Waves in NbSe2 and muSR studies of Nickel doping in BaFe2As 2

    Science.gov (United States)

    Arguello Ortiz, Carlos Jose

    Scanning Tunneling Microscopy is a very powerful technique to study electronic properties of condensed matter systems at the nanoscale. Part I of this thesis describes my work on Charge Density Waves (CDW) in NbSe2. NbSe2 is a layered dichalcogenide that has a CDW phase below 33K. We describe our study of the phase transition from the normal phase to the CDW phase at atomic scales. This is more relevant in light of recent discoveries of charge order in cuprates. Brand new research has shed some light about the relationship between the pseudogap phase, charge order and superconductivity in cuprates. The behavior of the CDW phase in NbSe 2 described in chapter 3 is strongly reminiscent of this physics of cuprates. NbSe2 is an excellent test bed for the study of the effect of impurities in correlated phases. In chapter 4 we revisit the cause of CDW formation in NbSe2. By including a very dilute concentration of impurities, we obtain information of the electronic bands of the material in the CDW phase. Based on this information, we are able to discuss the relationship between nesting, electron-phonon coupling and CDW in NbSe2. We demonstrate that by combining quasiparticle interference data with additional knowledge of the quasiparticle band structure from angle resolved photoemission measurements, one can extract the wavevector and energy dependence of the important electronic scattering processes. Part II focuses on Muon Spin Rotation and its application to the study of high-Tc superconductors. We describe our muSR studies on Nickel doped BaFe 2As2. By analyzing several doping concentrations, we explore the phase diagram in the antiferromagnetic and in the superconducting phases. This discussion also includes a detailed discussion of a doping concentration which falls in-between the AF and the SC phase.

  1. Fiber coupled ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1997-01-01

    We report on a scanning tunneling microscope with a photoconductive gate in the tunneling current circuit. The tunneling tip is attached to a coplanar transmission line with an integrated photoconductive switch. The switch is illuminated through a fiber which is rigidly attached to the switch...

  2. Scanning quantum decoherence microscopy.

    Science.gov (United States)

    Cole, Jared H; Hollenberg, Lloyd C L

    2009-12-09

    The use of qubits as sensitive nanoscale magnetometers has been studied theoretically and recently demonstrated experimentally. In this paper we propose a new concept, in which a scanning two-state quantum system is used to probe a sample through the subtle effects of decoherence. Mapping both the Hamiltonian and decoherence properties of a qubit simultaneously provides a unique image of the magnetic (or electric) field properties at the nanoscale. The resulting images are sensitive to the temporal as well as spatial variation in the fields created by the sample. As examples we theoretically study two applications; one from condensed matter physics, the other biophysics. The individual components required to realize the simplest version of this device (characterization and measurement of qubits, nanoscale positioning) have already been demonstrated experimentally.

  3. High Pressure Scanning Tunneling Microscopy and High PressureX-ray Photoemission Spectroscopy Studies of Adsorbate Structure,Composition and Mobility during Catalytic Reactions on A Model SingleCrystal

    Energy Technology Data Exchange (ETDEWEB)

    Montano, Max O. [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    Our research focuses on taking advantage of the ability of scanning tunneling microscopy (STM) to operate at high-temperatures and high-pressures while still providing real-time atomic resolution images. We also utilize high-pressure x-ray photoelectron spectroscopy (HPXPS) to monitor systems under identical conditions thus giving us chemical information to compare and contrast with the structural and dynamic data provided by STM.

  4. The growth of epitaxial iron oxides on platinum (111) as studied by X-ray photoelectron diffraction, scanning tunneling microscopy, and low energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong -Joo [Univ. of California, Berkeley, CA (United States)

    1995-05-01

    Three complementary surface structure probes, x-ray photoelectron diffraction (XPD), scanning tunneling microscopy (STM), and low-energy electron diffraction (LEED) have been combined in a single instrument. This experimental system has been utilized to study the structure and growth mechanisms of iron oxide films on Pt(111); these films were formed by first depositing a single overlayer of Fe with a certain coverage in monolayers (ML`s), and then thermally oxidizing it in an oxygen atmosphere. For films up to ~1 ML in thickness, a bilayer of Fe and O similar to those in FeO(111) is found to form. In agreement with prior studies, STM and LEED show this to be an incommensurate oxide film forming a lateral superlattice with short- and long-range periodicities of ~3.1 Å and ~26.0 Å. XPD in addition shows a topmost oxygen layer to be relaxed inward by -0.6 Å compared to bulk FeO(111), and these are new structural conclusions. The oxygen stacking in the FeO(111) bilayer is dominated by one of two possible binding sites. For thicker iron oxide films from 1.25 ML to 3.0 ML, the growth mode is essentially Stranski-Krastanov: iron oxide islands form on top of the FeO(111) bilayer mentioned above. For iron oxide films of 3.0 ML thickness, x-ray photoelectron spectroscopy (XPS) yields an Fe 2p3/2 binding energy and an Fe:O stoichiometry consistent with the presence of Fe3O4. Our XPD data further prove this overlayer to be Fe3O4(111)-magnetite in two almost equally populated domains with a 180° rotation between them. The structural parameters for this Fe3O4 overlayer generally agree with those of a previous LEED study, except that we find a significant difference in the first Fe-O interplanar spacing. This work demonstrates the considerable benefits to be derived by using this set of complementary surface structure probes in such epitaxial growth studies.

  5. Spectroscopic Imaging Scanning Tunneling Microscopy Studies of Electronic Structure in the Superconducting and Pseudogap Phases of Cuprate High-Tc Superconductors

    Science.gov (United States)

    Fujita, Kazuhiro; Schmidt, Andrew R.; Kim, Eun-Ah; Lawler, Michael J.; Lee, Dung Hai; Davis, J. C.; Eisaki, Hiroshi; Uchida, Shin-ichi

    2012-01-01

    One of the key motivations for the development of atomically resolved spectroscopic imaging scanning tunneling microscopy (SI-STM) has been to probe the electronic structure of cuprate high temperature superconductors. In both the d-wave superconducting (dSC) and the pseudogap (PG) phases of underdoped cuprates, two distinct classes of electronic states are observed using SI-STM. The first class consists of the dispersive Bogoliubov quasiparticles of a homogeneous d-wave superconductor. These are detected below a lower energy scale |E|=Δ0 and only upon a momentum space (k-space) arc which terminates near the lines connecting k=±(π/a0,0) to k=±(0,π/a0). Below optimal doping, this ``nodal'' arc shrinks continuously with decreasing hole density. In both the dSC and PG phases, the only broken symmetries detected in the |E|≤Δ0 states are those of a d-wave superconductor. The second class of states occurs at energies near the pseudogap energy scale |E|˜ Δ1 which is associated conventionally with the ``antinodal'' states near k=±(π/a0,0) and k=±(0,π/a0). We find that these states break the expected 90°-rotational (C4) symmetry of electronic structure within CuO2 unit cells, at least down to 180°-rotational (C2) symmetry (nematic) but in a spatially disordered fashion. This intra-unit-cell C4 symmetry breaking coexists at |E|˜Δ1 with incommensurate conductance modulations locally breaking both rotational and translational symmetries (smectic). The characteristic wavevector Q of the latter is determined, empirically, by the k-space points where Bogoliubov quasiparticle interference terminates, and therefore evolves continuously with doping. The properties of these two classes of |E|˜Δ1 states are indistinguishable in the dSC and PG phases. To explain this segregation of k-space into the two regimes distinguished by the symmetries of their electronic states and their energy scales |E|˜Δ1 and |E|≤Δ0, and to understand how this impacts the electronic

  6. Scanning Tunneling Microscopy and X-Ray Diffraction of Charge Density Wave Materials and the Rubidium Isotope Effect in Superconducting RUBIDIUM(3)CARBON(60)

    Science.gov (United States)

    Burk, Brian D.

    We image the surfaces of K_ {0.3}MoO_3 and Rb_{0.3}MoO_3 with scanning tunneling microscopy (STM) above and below the charge density wave (CDW) transition temperature (T_ p). Surprisingly, below T_ p real space and Fourier transformed images show no evidence of CDW modulation, suggesting a relatively small CDW amplitude at the sample surface. Furthermore, the lattice images that we obtained below T_ p are unaffected by the sliding of the CDW. With STM and x-ray diffraction we investigate the CDW domain structure of 1T-TaS_2 in the nearly commensurate (NC), triclinic (T), and incommensurate (I) phases. Fourier transformed STM images of the NC phase show fine satellite structure surrounding CDW peaks. The satellite structure confirms that the apparent domain-like modulation seen in real space images results from a true domain structure rather than from a moire pattern. STM images of the T phase indicate a surface striped domain pattern that is contrary to the previously reported stretched -honeycomb domain structure for the crystal bulk. In the T phase our x-ray diffraction measurements of CDW wave vectors and examination of fine satellite structure surrounding CDW peaks conclusively demonstrate that the bulk domain pattern is striped. We find that the bulk and surface domain structures are identical. X-ray diffraction of the I phase reveals weak satellites near CDW peaks. The satellite structure indicates a short wavelength, periodic amplitude and phase modulation of the CDW in a case where the CDW is far from commensurability. We measure the resistive superconducting transition temperature in C_{60} single crystals intercalated with isotopically pure ^{87}Rb and ^{85 }Rb and with natural abundance rubidium. We obtain a rubidium isotope effect exponent of alpha_{Rb} = -0.028 +/- 0.036, a result which implies that the Rb-C_ {60} optic phonons play at most a minor role in the pairing mechanism of Rb_3C _{60}..

  7. Vacuum scanning capillary photoemission microscopy

    DEFF Research Database (Denmark)

    Aseyev, S.A.; Cherkun, A P; Mironov, B N

    2017-01-01

    We demonstrate the use of a conical capillary in a scanning probe microscopy for surface analysis. The probe can measure photoemission from a substrate by transmitting photoelectrons along the capillary as a function of probe position. The technique is demonstrated on a model substrate consisting...

  8. High Resolution Scanning Ion Microscopy

    NARCIS (Netherlands)

    Castaldo, V.

    2011-01-01

    The structure of the thesis is the following. The first chapter is an introduction to scanning microscopy, where the path that led to the Focused Ion Beam (FIB) is described and the main differences between electrons and ion beams are highlighted. Chapter 2 is what is normally referred to (which I

  9. Scanning electron microscopy of molluscum contagiosum*

    Science.gov (United States)

    de Almeida Jr, Hiram Larangeira; Abuchaim, Martha Oliveira; Schneider, Maiko Abel; Marques, Leandra; de Castro, Luis Antônio Suíta

    2013-01-01

    Molluscum contagiosum is a disease caused by a poxvirus. It is more prevalent in children up to 5 years of age. There is a second peak of incidence in young adults. In order to examine its ultrastructure, three lesions were curetted without disruption, cut transversely with a scalpel, and routinely processed for scanning electron microscopy (SEM). The oval structure of molluscum contagiosum could be easily identified. In its core, there was a central umbilication and just below this depression, there was a keratinized tunnel. Under higher magnification, a proliferation similar to the epidermis was seen. Moreover, there were areas of cells disposed like a mosaic. Under higher magnification, rounded structures measuring 0.4 micron could be observed at the end of the keratinized tunnel and on the surface of the lesion. PMID:23539009

  10. New approach towards imaging λ-DNA using scanning tunneling ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. A new methodology to anchor λ-DNA to silanized n-Si(111) surface using Langmuir Blodget trough was developed. The n-Si (111) was silanized by treating it with low molecular weight octyltrichlorosi- lane in toluene. Scanning tunneling microscopy (STM) image of λ-DNA on octyltrichlorosilane deposited Si.

  11. New approach towards imaging λ-DNA using scanning tunneling ...

    Indian Academy of Sciences (India)

    A new methodology to anchor -DNA to silanized -Si(111) surface using Langmuir Blodget trough was developed. The -Si (111) was silanized by treating it with low molecular weight octyltrichlorosilane in toluene. Scanning tunneling microscopy (STM) image of -DNA on octyltrichlorosilane deposited Si substrate ...

  12. Scanning tunneling spectroscopy of suspended single-wall carbon nanotubes

    NARCIS (Netherlands)

    LeRoy, B.J.; Lemay, S.G.; Kong, J.; Dekker, C.

    2004-01-01

    We have performed low-temperature scanning tunneling microscopy measurements on single-wall carbon nanotubes that are freely suspended over a trench. The nanotubes were grown by chemical vapor deposition on a Pt substrate with predefined trenches etched into it. Atomic resolution was obtained on the

  13. A Student-Built Scanning Tunneling Microscope

    Science.gov (United States)

    Ekkens, Tom

    2015-01-01

    Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

  14. Scanning tunneling spectroscopy of Pb thin films

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Michael

    2010-12-13

    The present thesis deals with the electronic structure, work function and single-atom contact conductance of Pb thin films, investigated with a low-temperature scanning tunneling microscope. The electronic structure of Pb(111) thin films on Ag(111) surfaces is investigated using scanning tunneling spectroscopy (STS). Quantum size effects, in particular, quantum well states (QWSs), play a crucial role in the electronic and physical properties of these films. Quantitative analysis of the spectra yields the QWS energies as a function of film thickness, the Pb bulk-band dispersion in {gamma}-L direction, scattering phase shifts at the Pb/Ag interface and vacuum barrier as well as the lifetime broadening at anti {gamma}. The work function {phi} is an important property of surfaces, which influences catalytic reactivity and charge injection at interfaces. It controls the availability of charge carriers in front of a surface. Modifying {phi} has been achieved by deposition of metals and molecules. For investigating {phi} at the atomic scale, scanning tunneling microscopy (STM) has become a widely used technique. STM measures an apparent barrier height {phi}{sub a}, which is commonly related to the sample work function {phi}{sub s} by: {phi}{sub a}=({phi}{sub s}+{phi}{sub t}- vertical stroke eV vertical stroke)/2, with {phi}{sub t} the work function of the tunneling tip, V the applied tunneling bias voltage, and -e the electron charge. Hence, the effect of the finite voltage in STM on {phi}{sub a} is assumed to be linear and the comparison of {phi}{sub a} measured at different surface sites is assumed to yield quantitative information about work function differences. Here, the dependence of {phi}{sub a} on the Pb film thickness and applied bias voltage V is investigated. {phi}{sub a} is found to vary significantly with V. This bias dependence leads to drastic changes and even inversion of contrast in spatial maps of {phi}{sub a}, which are related to the QWSs in the Pb

  15. QUANTITATIVE CONFOCAL LASER SCANNING MICROSCOPY

    Directory of Open Access Journals (Sweden)

    Merete Krog Raarup

    2011-05-01

    Full Text Available This paper discusses recent advances in confocal laser scanning microscopy (CLSM for imaging of 3D structure as well as quantitative characterization of biomolecular interactions and diffusion behaviour by means of one- and two-photon excitation. The use of CLSM for improved stereological length estimation in thick (up to 0.5 mm tissue is proposed. The techniques of FRET (Fluorescence Resonance Energy Transfer, FLIM (Fluorescence Lifetime Imaging Microscopy, FCS (Fluorescence Correlation Spectroscopy and FRAP (Fluorescence Recovery After Photobleaching are introduced and their applicability for quantitative imaging of biomolecular (co-localization and trafficking in live cells described. The advantage of two-photon versus one-photon excitation in relation to these techniques is discussed.

  16. Open Source Scanning Probe Microscopy Control Software Package Gxsm

    Energy Technology Data Exchange (ETDEWEB)

    Zahl P.; Wagner, T.; Moller, R.; Klust, A.

    2009-08-10

    Gxsm is a full featured and modern scanning probe microscopy (SPM) software. It can be used for powerful multidimensional image/data processing, analysis, and visualization. Connected toan instrument, it is operating many different avors of SPM, e.g., scanning tunneling microscopy(STM) and atomic force microscopy (AFM) or in general two-dimensional multi channel data acquisition instruments. The Gxsm core can handle different data types, e.g., integer and oating point numbers. An easily extendable plug-in architecture provides many image analysis and manipulation functions. A digital signal processor (DSP) subsystem runs the feedback loop, generates the scanning signals and acquires the data during SPM measurements. The programmable Gxsm vector probe engine performs virtually any thinkable spectroscopy and manipulation task, such as scanning tunneling spectroscopy (STS) or tip formation. The Gxsm software is released under the GNU general public license (GPL) and can be obtained via the Internet.

  17. Multifunctional scanning ion conductance microscopy.

    Science.gov (United States)

    Page, Ashley; Perry, David; Unwin, Patrick R

    2017-04-01

    Scanning ion conductance microscopy (SICM) is a nanopipette-based technique that has traditionally been used to image topography or to deliver species to an interface, particularly in a biological setting. This article highlights the recent blossoming of SICM into a technique with a much greater diversity of applications and capability that can be used either standalone, with advanced control (potential-time) functions, or in tandem with other methods. SICM can be used to elucidate functional information about interfaces, such as surface charge density or electrochemical activity (ion fluxes). Using a multi-barrel probe format, SICM-related techniques can be employed to deposit nanoscale three-dimensional structures and further functionality is realized when SICM is combined with scanning electrochemical microscopy (SECM), with simultaneous measurements from a single probe opening up considerable prospects for multifunctional imaging. SICM studies are greatly enhanced by finite-element method modelling for quantitative treatment of issues such as resolution, surface charge and (tip) geometry effects. SICM is particularly applicable to the study of living systems, notably single cells, although applications extend to materials characterization and to new methods of printing and nanofabrication. A more thorough understanding of the electrochemical principles and properties of SICM provides a foundation for significant applications of SICM in electrochemistry and interfacial science.

  18. Scanning tunneling microscope assembly, reactor, and system

    Science.gov (United States)

    Tao, Feng; Salmeron, Miquel; Somorjai, Gabor A

    2014-11-18

    An embodiment of a scanning tunneling microscope (STM) reactor includes a pressure vessel, an STM assembly, and three spring coupling objects. The pressure vessel includes a sealable port, an interior, and an exterior. An embodiment of an STM system includes a vacuum chamber, an STM reactor, and three springs. The three springs couple the STM reactor to the vacuum chamber and are operable to suspend the scanning tunneling microscope reactor within the interior of the vacuum chamber during operation of the STM reactor. An embodiment of an STM assembly includes a coarse displacement arrangement, a piezoelectric fine displacement scanning tube coupled to the coarse displacement arrangement, and a receiver. The piezoelectric fine displacement scanning tube is coupled to the coarse displacement arrangement. The receiver is coupled to the piezoelectric scanning tube and is operable to receive a tip holder, and the tip holder is operable to receive a tip.

  19. Optimizing qPlus sensor assemblies for simultaneous scanning tunneling and noncontact atomic force microscopy operation based on finite element method analysis

    Directory of Open Access Journals (Sweden)

    Omur E. Dagdeviren

    2017-03-01

    Full Text Available Quartz tuning forks that have a probe tip attached to the end of one of its prongs while the other prong is arrested to a holder (“qPlus” configuration have gained considerable popularity in recent years for high-resolution atomic force microscopy imaging. The small size of the tuning forks and the complexity of the sensor architecture, however, often impede predictions on how variations in the execution of the individual assembly steps affect the performance of the completed sensor. Extending an earlier study that provided numerical analysis of qPlus-style setups without tips, this work quantifies the influence of tip attachment on the operational characteristics of the sensor. The results using finite element modeling show in particular that for setups that include a metallic tip that is connected via a separate wire to enable the simultaneous collection of local forces and tunneling currents, the exact realization of this wire connection has a major effect on sensor properties such as spring constant, quality factor, resonance frequency, and its deviation from an ideal vertical oscillation.

  20. Optimizing qPlus sensor assemblies for simultaneous scanning tunneling and noncontact atomic force microscopy operation based on finite element method analysis.

    Science.gov (United States)

    Dagdeviren, Omur E; Schwarz, Udo D

    2017-01-01

    Quartz tuning forks that have a probe tip attached to the end of one of its prongs while the other prong is arrested to a holder ("qPlus" configuration) have gained considerable popularity in recent years for high-resolution atomic force microscopy imaging. The small size of the tuning forks and the complexity of the sensor architecture, however, often impede predictions on how variations in the execution of the individual assembly steps affect the performance of the completed sensor. Extending an earlier study that provided numerical analysis of qPlus-style setups without tips, this work quantifies the influence of tip attachment on the operational characteristics of the sensor. The results using finite element modeling show in particular that for setups that include a metallic tip that is connected via a separate wire to enable the simultaneous collection of local forces and tunneling currents, the exact realization of this wire connection has a major effect on sensor properties such as spring constant, quality factor, resonance frequency, and its deviation from an ideal vertical oscillation.

  1. Reversible Hydrogenation and Bandgap Opening of Graphene and Graphite Surfaces Probed by Scanning Tunneling Spectroscopy

    NARCIS (Netherlands)

    Castellanos-Gomez, Andres; Wojtaszek, Magdalena; Arramel, [No Value; Tombros, Nikolaos; van Wees, Bart J.

    2012-01-01

    The effects of hydrogenation on the topography and electronic properties of graphene and graphite surfaces are studied by scanning tunneling microscopy and spectroscopy. The surfaces are chemically modified using an Ar/H2 plasma. By analyzing thousands of scanning tunneling spectroscopy measurements

  2. Scanning tunneling spectroscopy of CdSe nanocrystals covalently bound to GaAs

    DEFF Research Database (Denmark)

    Walzer, K.; Marx, E.; Greenham, N.C.

    2003-01-01

    We present scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements of CdSe nanocrystals covalently attached to doped GaAs substrates using monolayers of 1,6-hexanedithiol. STM measurements showed the formation of stable, densely packed, homogeneous monolayers...

  3. Scanning Electrochemical Microscopy in Neuroscience

    Science.gov (United States)

    Schulte, Albert; Nebel, Michaela; Schuhmann, Wolfgang

    2010-07-01

    This article reviews recent work involving the application of scanning electrochemical microscopy (SECM) to the study of individual cultured living cells, with an emphasis on topographical and functional imaging of neuronal and secretory cells of the nervous and endocrine system. The basic principles of biological SECM and associated negative amperometric-feedback and generator/collector-mode SECM imaging are discussed, and successful use of the methodology for screening soft and fragile membranous objects is outlined. The drawbacks of the constant-height mode of probe movement and the benefits of the constant-distance mode of SECM operation are described. Finally, representative examples of constant-height and constant-distance mode SECM on a variety of live cells are highlighted to demonstrate the current status of single-cell SECM in general and of SECM in neuroscience in particular.

  4. EDITORIAL: Scanning probe microscopy: a visionary development Scanning probe microscopy: a visionary development

    Science.gov (United States)

    Demming, Anna

    2013-07-01

    The development of scanning probe microscopy repositioned modern physics. When Rohrer and Binnig first used electronic tunnelling effects to image atoms and quantum states they did more than pin down theoretical hypotheses to real-world observables; the scanning tunnelling microscope fed imaginations, prompting researchers to consider new directions and possibilities [1]. As Rohrer once commented, 'We could show that you can easily manipulate or position something small in space with an accuracy of 10 pm.... When you can do that, you simply have ideas of what you can do' [2]. The development heralded a cavalry of scanning probe techniques—such as atomic force microscopy (AFM) [3-5], scanning near-field optical microscopy (SNOM) [6-8] and Kelvin probe force microscopy (KPFM) [9, 10]—that still continue to bring nanomaterials and nanoscale phenomena into fresh focus. Not long after the development of scanning tunnelling microscopy, Binnig, Quate and Gerber collaborating in California in the US published work on a new type of microscope also capable of atomic level resolution [3]. The original concept behind scanning tunnelling microscopy uses electrical conductance, which places substantial limitations on the systems that it can image. Binnig, Quate and Gerber developed the AFM to 'feel' the topology of surfaces like the needle of an old fashioned vinyl player. In this way insulators could be imaged as well. The development of a force modulation mode AFM extended the tool's reach to soft materials making images of biological samples accessible with the technique [4]. There have now been a number of demonstrations of image capture at rates that allow dynamics at the nanoscale to be tracked in real time, opening further possibilities in applications of the AFM as described in a recent review by Toshio Ando at Kanazawa University [5]. Researchers also found a way to retrieve optical information at 'super-resolution' [6, 7]. Optical microscopy provides spectral

  5. Conductivity map from scanning tunneling potentiometry.

    Science.gov (United States)

    Zhang, Hao; Li, Xianqi; Chen, Yunmei; Durand, Corentin; Li, An-Ping; Zhang, X-G

    2016-08-01

    We present a novel method for extracting two-dimensional (2D) conductivity profiles from large electrochemical potential datasets acquired by scanning tunneling potentiometry of a 2D conductor. The method consists of a data preprocessing procedure to reduce/eliminate noise and a numerical conductivity reconstruction. The preprocessing procedure employs an inverse consistent image registration method to align the forward and backward scans of the same line for each image line followed by a total variation (TV) based image restoration method to obtain a (nearly) noise-free potential from the aligned scans. The preprocessed potential is then used for numerical conductivity reconstruction, based on a TV model solved by accelerated alternating direction method of multiplier. The method is demonstrated on a measurement of the grain boundary of a monolayer graphene, yielding a nearly 10:1 ratio for the grain boundary resistivity over bulk resistivity.

  6. Conductivity map from scanning tunneling potentiometry

    Science.gov (United States)

    Zhang, Hao; Li, Xianqi; Chen, Yunmei; Durand, Corentin; Li, An-Ping; Zhang, X.-G.

    2016-08-01

    We present a novel method for extracting two-dimensional (2D) conductivity profiles from large electrochemical potential datasets acquired by scanning tunneling potentiometry of a 2D conductor. The method consists of a data preprocessing procedure to reduce/eliminate noise and a numerical conductivity reconstruction. The preprocessing procedure employs an inverse consistent image registration method to align the forward and backward scans of the same line for each image line followed by a total variation (TV) based image restoration method to obtain a (nearly) noise-free potential from the aligned scans. The preprocessed potential is then used for numerical conductivity reconstruction, based on a TV model solved by accelerated alternating direction method of multiplier. The method is demonstrated on a measurement of the grain boundary of a monolayer graphene, yielding a nearly 10:1 ratio for the grain boundary resistivity over bulk resistivity.

  7. Scanning tunneling microscopy study of morphology and electronic properties in (K{sub 0.7}Na{sub 0.3})Fe{sub 2−y}Se{sub 2} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Trifonov, A. S., E-mail: trifonov.artem@phys.msu.ru; Presnov, D. E. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 1(2), Leninskie Gory, GSP-1, Moscow 119991 (Russian Federation); Low Temperature Physics and Superconductivity Department, Physics Faculty, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Ovchenkov, Y. A. [Low Temperature Physics and Superconductivity Department, Physics Faculty, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Belosludov, R. [Institute for Materials Research, Tohoku University, 980-8577 Sendai (Japan); Boltalin, A. I.; Liu, M.; Morozov, I. V. [Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Nejo, H. [National Institute for Material Science, Tsukuba 305-0047 (Japan); Vasiliev, A. N. [Low Temperature Physics and Superconductivity Department, Physics Faculty, Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Theoretical Physics and Applied Mathematics Department, Institute of Physics and Technology, Ural Federal University, Ekaterinburg 620002 (Russian Federation); National University of Science and Technology ' MISiS' , Moscow 119049 (Russian Federation)

    2014-07-28

    We investigated the microstructure of the iron selenide superconductor (K{sub 0.7}Na{sub 0.3})Fe{sub 2−y}Se{sub 2} with a T{sub c} = 32 K and a near 100% Meissner screening volume fraction. Topography and electron transport properties were studied using electron microscopy and ultra-high vacuum scanning tunneling microscopy (STM) techniques. Room temperature STM measurements reliably identify spatial variations of the local electronic properties of this material. The studied crystals consist of continuous regions with significantly different shapes of current-voltage curves reflecting different electronic transport properties of these regions. Fitting of the local current-voltage curves with the Simmons model for metal-dielectric-metal structure confirmed a phase separation in the sample to a metal and semiconducting phases. The observed regions have dimensions in the range of several tenths of a micrometer and indicate a phase separation in the sample.

  8. Low-temperature scanning tunneling spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kirk, M.D.

    1989-01-01

    A scanning tunneling microscope (STM) was designed and built to operate at liquid helium temperature and was used to measure highly localized electron tunneling spectroscopy. Several instruments were built, all capable of operating in many different environments: air, vacuum, liquid helium and in a transfer gas. An adaptation of one particular design was made into an atomic force microscope capable of operating at low temperatures. Using a low temperature STM, three adsorbed molecular species (liquid crystals, sorbic acid, and carbon monoxide), deposited on a graphite substrate, have been imaged at 4.2K. The inelastic tunneling spectra of these adsorbates show strong peaks in dI/dV vs V curves at energies that correspond to known vibrational modes. The increase in conductance at the onset of inelastic tunneling was measured to be as high as 100 times. The spatial variation of the spectra was measured and was seen to change dramatically on the scale of angstroms, suggesting that individual molecular bonds could be measured. A theoretical model is presented to explain the contrast seen in the STM images of adsorbed molecules, thereby explaining why adsorbed molecules appear to be more conductive than the background. The microscope proved very useful for measuring the energy gap of high temperature superconductors. These materials often have submicron grain sizes. For LaSrCuO, YBaCuO, and BiCaSrCuO, the conductance curves showed a large energy gap suggesting a strongly coupled superconductor. The conductance curves also indicated that intergrain tunneling may occur and that the background conductance varied linearly with the applied voltage. The crystalline structure of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} was imaged by an STM operating in air and in ultra-high vacuum.

  9. Exhibition of tunnel coupling of negatively charged dangling bonds on Si Surface Using Scanning Tunneling Microscope

    Science.gov (United States)

    Haider, M. Baseer; Livadaru, L.; Pitters, J.; Wolkow, R.

    2011-03-01

    We have performed Scanning tunneling microscopy study of hydrogen terminated Si (100). We will show that single Si atoms in a solid state environment can be served as quantum dots. These negatively charged quantum dots can be tunnel coupled to the nearby Si quantum dots. We will demonstrate that this tunnel coupling can be controlled by adjusting the separation between the two Si atomic quantum dots. Moreover electron occupation in the tunnel coupled Si quantum dots can be controlled. We have used this tunnel coupling effect of Si atomic quantum dots to fabricate Quantum Cellular Automata Cells. Quantum Cellular Automata are used to transmit binary information through electrostatic interaction between adjacent cells without the transfer of charge from one cell to the next. Devices based on Quantum Cellular Automata will consume much less power compared to the conventional transistor based devices. Moreover, since there is no transfer of charge so power dissipation during its operation is minimal compared to conventional semiconductor devices. This Si based Quantum Cellular Automat Cell works at room temperature.

  10. Scanning Electron Microscopy in modern dentistry research

    OpenAIRE

    Paradella, Thaís Cachuté; Unesp-FOSJC; Bottino, Marco Antonio; Unesp-FOSJC

    2012-01-01

    The purpose of this article was to review the usage of Scanning Electron Microscopy (SEM) in dentistry research nowadays, through a careful and updated literature review. By using the key-words Scanning Electron Microscopy and one of the following areas of research in dentistry (Endodontics, Periodontics and Implant), in international database (PubMed), in the year of 2012 (from January to September), a total of 112 articles were found. This data was tabled and the articles were classified ac...

  11. Differential-concentration scanning ion conductance microscopy

    OpenAIRE

    Perry, David; Page, Ashley; Chen, Baoping; Frenguelli, Bruno G.; Unwin, Patrick R.

    2017-01-01

    Scanning ion conductance microscopy (SICM) is a nanopipette-based scanning probe microscopy technique that utilizes the ionic current flowing between an electrode inserted inside a nanopipette probe containing electrolyte solution and a second electrode placed in a bulk electrolyte bath, to provide information on a substrate of interest. For most applications to date, the composition and concentration of the electrolyte inside and outside the nanopipette is identical, but it is shown herein t...

  12. SPATIAL REPARTITION OF CURRENT FLUCTUATIONS IN A SCANNING TUNNELING MICROSCOPE

    Directory of Open Access Journals (Sweden)

    Jerome Lagoute

    2011-05-01

    Full Text Available Scanning Tunneling Microscopy (STM is a technique where the surface topography of a conducting sample is probed by a scanning metallic tip. The tip-to-surface distance is controlled by monitoring the electronic tunneling current between the two metals. The aim of this work is to extend the temporal range of this instrument by characterising the time fluctuations of this current on different surfaces. The current noise power spectral density is dominated by a characteristic 1/f component, the physical origin of which is not yet clearly identified, despite a number of investigations. A new I-V preamplifier was developed in order to characterise these fluctuations of the tunnelling current and to obtain images of their spatial repartition. It is observed that their intensity is correlated with some topographical features. This information can be used to get insights on the physical phenomena involved that are not accessible by the usual STM set-up, which is limited to low frequencies.

  13. Epitaxial BaTiO{sub 3}(100) films on Pt(100): A low-energy electron diffraction, scanning tunneling microscopy, and x-ray photoelectron spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, Stefan; Huth, Michael; Schindler, Karl-Michael; Widdra, Wolf [Institute of Physics, Martin-Luther-Universitaet Halle-Wittenberg, Halle (Germany)

    2011-09-14

    The growth of epitaxial ultrathin BaTiO{sub 3} films on a Pt(100) substrate has been studied by scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and x-ray photoelectron spectroscopy (XPS). The films have been prepared by radio-frequency-assisted magnetron sputter deposition at room temperature and develop a long-range order upon annealing at 900 K in O{sub 2}. By adjusting the Ar and O{sub 2} partial pressures of the sputter gas, the stoichiometry was tuned to match that of a BaTiO{sub 3}(100) single crystal as determined by XPS. STM reveals the growth of continuous BaTiO{sub 3} films with unit cell high islands on top. With LEED already for monolayer thicknesses, the formation of a BaTiO{sub 3}(100)-(1 x 1) structure has been observed. Films of 2-3 unit cell thickness show a brilliant (1 x 1) LEED pattern for which an extended set of LEED I-V data has been acquired. At temperatures above 1050 K the BaTiO{sub 3} thin film starts to decay by formation of vacancy islands. In addition (4 x 4) and (3 x 3) surface reconstructions develop upon prolonged heating.

  14. Atomic structure of the indium-induced Ge(001)(¤n¤x4) surface reconstruction determined by scanning tunneling microscopy and ¤ab initio¤ calculations

    DEFF Research Database (Denmark)

    Falkenberg, G.; Bunk, O.; Johnson, R.L.

    2002-01-01

    . Sci. 123/124, 104 (1998) for In on Si(001). For the (4x4) subunit, we propose a model that includes the main features of the (3x4) subunit together with additional mixed Ge-In dimers. The atomic positions were optimized using ab initio total-energy calculations. The calculated local densities......Using scanning-tunneling microscopy (STM) and first-principles total-energy calculations, we have determined the atomic geometry of the superstructures formed by the adsorption of up to 0.5 monolayer of indium on Ge(001) and annealing at temperatures above 200 degreesC. A strong interaction between...... indium adatoms and the germanium substrate atoms leads to the formation of two different In-Ge subunits on the Ge(001) surface. In the subsaturation regime separate (nx4) subunits are observed where n can be either 3 or 4 and the STM images resemble those of the Si(001)-(3x4)-In and -Al reconstructions...

  15. Spiral scanning method for atomic force microscopy.

    Science.gov (United States)

    Hung, Shao-Kang

    2010-07-01

    A spiral scanning method is proposed for atomic force microscopy with thoroughgoing analysis and implementation. Comparing with the traditional line-by-line scanning method, the spiral scanning method demonstrates higher imaging speed, minor image distortion, and lower acceleration, which can damage the piezoelectric scanner. Employing the spiral scanning method to replace the line-by-line scanning method, the experiment shows that the time to complete an imaging cycle can be reduced from 800 s to 314 s without sacrificing the image resolution.

  16. Scanning electron microscopy of bone.

    Science.gov (United States)

    Boyde, Alan

    2012-01-01

    This chapter described methods for Scanning Electron Microscopical imaging of bone and bone cells. Backscattered electron (BSE) imaging is by far the most useful in the bone field, followed by secondary electrons (SE) and the energy dispersive X-ray (EDX) analytical modes. This chapter considers preparing and imaging samples of unembedded bone having 3D detail in a 3D surface, topography-free, polished or micromilled, resin-embedded block surfaces, and resin casts of space in bone matrix. The chapter considers methods for fixation, drying, looking at undersides of bone cells, and coating. Maceration with alkaline bacterial pronase, hypochlorite, hydrogen peroxide, and sodium or potassium hydroxide to remove cells and unmineralised matrix is described in detail. Attention is given especially to methods for 3D BSE SEM imaging of bone samples and recommendations for the types of resin embedding of bone for BSE imaging are given. Correlated confocal and SEM imaging of PMMA-embedded bone requires the use of glycerol to coverslip. Cathodoluminescence (CL) mode SEM imaging is an alternative for visualising fluorescent mineralising front labels such as calcein and tetracyclines. Making spatial casts from PMMA or other resin embedded samples is an important use of this material. Correlation with other imaging means, including microradiography and microtomography is important. Shipping wet bone samples between labs is best done in glycerol. Environmental SEM (ESEM, controlled vacuum mode) is valuable in eliminating -"charging" problems which are common with complex, cancellous bone samples.

  17. Scanning tunneling microscope spectroscopy of polymers.

    Science.gov (United States)

    Zypman, Fredy R

    2002-01-01

    This paper presents theoretical results on the relationship between density of states (DOS) and scanning tunneling microscope current-voltage curves in polymers. We considered samples of linear hydrocarbons electrically grounded at one of their extremes. The other extreme is electrically connected to the microscope tip via electron tunneling through vacuum. When a voltage, V, is applied to the tip, electric current, I, flows in the tip-sample circuit. This current varies as the voltage varies and depends on the DOS to the extent that no current would flow if no electron states exist at a certain energy (or voltage). The detailed relationship between DOS and the current-voltage (I-V) curve is not known a priori. We solve the corresponding quantum problem in the context of tight binding and find that I-V reproduces accurately the resonant energy peaks of the DOS. We apply the results to 100 atom-long alkane and alkene chains and found that there is a significant voltage shift in the corresponding curves as to discriminate one structure from the other.

  18. First-principles theory of inelastic currents in a scanning tunneling microscope

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Hu, Ben Yu-Kuang; Thirstrup, C.

    1998-01-01

    A first-principles theory of inelastic tunneling between a model probe tip and an atom adsorbed on a surface is presented, extending the elastic tunneling theory of Tersoff and Hamann. The inelastic current is proportional to the change in the local density of states at the center of the tip due...... to the addition of the adsorbate. We use the theory to investigate the vibrational heating of an adsorbate below a scanning tunneling microscopy tip. We calculate the desorption rate of PI from Si(100)-H(2 X 1) as a function of the sample bias and tunnel current, and find excellent a,agreement with recent...

  19. Manipulation of magnetic skyrmions with a scanning tunneling microscope

    Science.gov (United States)

    Wieser, R.; Shindou, R.; Xie, X. C.

    2017-02-01

    The dynamics of a single magnetic skyrmion in an atomic spin system under the influence of a scanning tunneling microscope is investigated by computer simulations solving the Landau-Lifshitz-Gilbert equation. Two possible scenarios are described: manipulation with aid of a spin-polarized tunneling current and by an electric field created by the scanning tunneling microscope. The dynamics during the creation and annihilation process is studied and the possibility to move single skyrmions is showed.

  20. A scanning tunneling microscopy investigation of the phases formed by the sulfur adsorption on Au(100) from an alkaline solution of 1,4-piperazine(bis)-dithiocarbamate of potassium

    Energy Technology Data Exchange (ETDEWEB)

    Martínez, Javier A. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, El Vedado, Plaza de la Revolución, La Habana 10400 (Cuba); Valenzuela B, José [Centro de Nanociencias y Nanotecnología (CNyN), Universidad Nacional Autónoma de México (UNAM) , km 107 Carretera Tijuana-Ensenada, Ensenada, BC 22860 (Mexico); Cao Milán, R. [Facultad de Química, Universidad de La Habana, Zapata y G, El Vedado, Plaza de la Revolución, La Habana 10400 (Cuba); Herrera, José [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, El Vedado, Plaza de la Revolución, La Habana 10400 (Cuba); Farías, Mario H. [Centro de Nanociencias y Nanotecnología (CNyN), Universidad Nacional Autónoma de México (UNAM) , km 107 Carretera Tijuana-Ensenada, Ensenada, BC 22860 (Mexico); Hernández, Mayra P., E-mail: mayrap@fisica.uh.cu [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, El Vedado, Plaza de la Revolución, La Habana 10400 (Cuba)

    2014-11-30

    Highlights: • New phases of sulfur on gold: hexamer and (√(2)×√(2)) were observed by STM. • Hexamers and (√(2)×√(2)) structures coexist with well-known octomers. • Formation of sulfur multilayer by K{sub 2}DTC{sub 2}pz hydrolysis under alkaline condition. • Top octomer layer have dynamic behavior while (√(2)×√(2)) and hexamer were static. • A model is presented to explain sulfur multilayer formation on Au(100). - Abstract: Piperazine-dithiocarbamate of potassium (K{sub 2}DTC{sub 2}pz) was used as a new precursor for the spontaneous deposition of sulfur on the Au(100) surface in alkaline solution. Two new sulfur phases were studied by scanning tunneling microscopy (STM). These phases were formed by six sulfur atoms (S{sub 6} phase, hexamer) and by four sulfur atoms (S{sub 4} phase, tetramer with (√(2)×√(2)) structure), and they were observed in coexistence with the well-known quasi-square patterns formed by eight sulfur atoms (S{sub 8} phase, octomer). A model was proposed where sulfur multilayers were formed by a (√(2)×√(2)) phase adsorbed directly on the gold surface while one of the other structures: hexamers or octomers were deposited on top. Sulfur layers were formed on gold terraces, vacancies and islands produced by lifting reconstructed surface. Sequential high-resolution STM images allowed the direct observation of the dynamic of the octomers, while the (√(2)×√(2)) structure remained static. Images also showed the reversible association/dissociation of the octomer.

  1. Investigations on the electronic surface properties of the stoichiometric superconductor LiFeAs using scanning tunneling microscopy and spectroscopy; Untersuchung der elektronischen Oberflaecheneigenschaften des stoechiometrischen Supraleiters LiFeAs mittels Rastertunnelmikroskopie und -spektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, Ronny

    2014-09-29

    This work presents scanning tunneling microscopy and spectroscopy investigations on the stoichiometric superconductor lithium iron arsenide (LiFeAs). To reveal the electronic properties, measurements on defect-free surfaces as well as near defects have been performed. The former shows a shift of atomic position with respect to the applied bias voltage. Furthermore, temperature dependent spectroscopic measurements indicate the coupling of quasiparticles in the vicinity of the superconducting coherence peaks. LiFeAs surfaces influenced by atomic defects show a spacial variation of the superconducting gap. The defects can be characterized by their symmetry and thus can be assigned to a position in the atomic lattice. Detailed spectroscopic investigations of defects reveal their influence on the quasiparticle density of states. In particular, Fe-defects show a small effect on the superconductivity while As-defects strongly disturb the superconducting gap. Measurements in magnetic field have been performed for the determination of the Ginzburg-Landau coherence length ξ{sub GL}. For this purpose, a suitable fit-function has been developed in this work. This function allows to fit the differential conductance of a magnetic vortex at E{sub F}. The fit results in a coherence length of ξ{sub GL} = 3,9 nm which corresponds to an upper critical field of 21 Tesla. Besides measurements on a single vortex, investigation on the vortex lattice have been performed. The vortex lattice constant follows thereby the predicted behavior of a trigonal vortex lattice. However, for magnetic fields larger than 6 Tesla an increasing lattice disorder sets in, presumably due to vortex-vortex-interactions.

  2. The interfacial and surface properties of thin Fe and Gd films grown on W(110) as studied by scanning tunneling microscopy, site-resolved photoelectron diffraction, and spin polarized photoelectron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Tober, Eric D. [Univ. of California, Davis, CA (United States)

    1997-06-01

    Combined scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) measurements from Gd films grown on W(110) prepared with and without annealing have been used to provide a detailed picture of the growth of such films, permitting a quantitative structural explanation for previously-measured magnetic properties and the identification of a new two-dimensional structure for the first monolayer. The analysis of the film roughness of room-temperature-grown films as a function of coverage and lateral length scale reveals that the growing Gd surface follows scaling laws for a self-affine surface. Annealing these as-deposited films at elevated temperatures is found to drastically alter the morphology of the films, as seen by both STM and LEED. Nanometer-scale islands of relatively well-defined size and shape are observed under certain conditions. Finally, the first monolayer of Gd is observed to form a (7x14) superstructure with pseudo-(7x7) symmetry that is consistent with a minimally-distorted hexagonal two-dimensional Gd(0001) film. Furthermore, a new beamline and photoelectron spectrometer/diffractometer at the Advanced Light Source have been used to obtain full-solid-angle and site-specific photoelectron diffraction (PD) data from interface W atoms just beneath (1x1) Fe and (7x14) Gd monolayers on W(110) by utilizing the core level shift in the W 4f7/2 spectrum. A comparison of experiment with multiple scattering calculations permits determining the Fe adsorption site and the relative interlayer spacing to the first and second W layers. These Fe results are also compared to those from the very different Gd overlayer and from the clean W(110) surface. Such interface PD measurements show considerable promise for future studies. Finally, the rare-earth ferromagnetic system of Gd(0001) has been examined through the use of spin polarized photoelectron diffraction from the Gd 4s and 5s photoelectron multiplets.

  3. Transfer functions in collection scanning near-field optical microscopy

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Vohnsen, Brian; Bozhevolnaya, Elena A.

    1999-01-01

    are considered with respect to the relation between near-field optical images and the corresponding intensity distributions. Our conclusions are supported with numerical simulations and experimental results obtained by using a photon scanning tunneling microscope with an uncoated fiber tip.......It is generally accepted that, if in collection near-field optical microscopy the probe-sample coupling can be disregarded, a fiber probe can be considered as a detector of the near-field intensity whose size can be accounted for via an intensity transfer function. We show that, in general...

  4. Scanning electron microscopy study of Trichomonas gallinae.

    Science.gov (United States)

    Tasca, Tiana; De Carli, Geraldo A

    2003-12-01

    A scanning electron microscopy (SEM) study of Trichomonas gallinae (Rivolta, 1878), provided more information about the morphology of this flagellated protozoan. SEM showed the morphological features of the trophozoites; the emergence of the anterior flagella, the structure of the undulating membrane, the position and shape of the pelta, axostyle and posterior flagellum. Of special interest were the pseudocyst forms.

  5. Laser scanning laser diode photoacoustic microscopy system.

    Science.gov (United States)

    Erfanzadeh, Mohsen; Kumavor, Patrick D; Zhu, Quing

    2018-03-01

    The development of low-cost and fast photoacoustic microscopy systems enhances the clinical applicability of photoacoustic imaging systems. To this end, we present a laser scanning laser diode-based photoacoustic microscopy system. In this system, a 905 nm, 325 W maximum output peak power pulsed laser diode with 50 ns pulsewidth is utilized as the light source. A combination of aspheric and cylindrical lenses is used for collimation of the laser diode beam. Two galvanometer scanning mirrors steer the beam across a focusing aspheric lens. The lateral resolution of the system was measured to be ∼21 μm using edge spread function estimation. No averaging was performed during data acquisition. The imaging speed is ∼370 A-lines per second. Photoacoustic microscopy images of human hairs, ex vivo mouse ear, and ex vivo porcine ovary are presented to demonstrate the feasibility and potentials of the proposed system.

  6. Aberration corrected Lorentz scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    McVitie, S., E-mail: stephen.mcvitie@glasgow.ac.uk; McGrouther, D.; McFadzean, S.; MacLaren, D.A.; O’Shea, K.J.; Benitez, M.J.

    2015-05-15

    We present results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment. We discuss the innovations in microscope instrumentation and additional hardware that underpin the imaging improvements in resolution and detection with a focus on developments in differential phase contrast microscopy. Examples from materials possessing nanometre scale variations in magnetisation illustrate the potential for aberration corrected Lorentz imaging as a tool to further our understanding of magnetism on this lengthscale. - Highlights: • Demonstration of nanometre scale resolution in magnetic field free environment using aberration correction in the scanning transmission electron microscope (STEM). • Implementation of differential phase contrast mode of Lorentz microscopy in aberration corrected STEM with improved sensitivity. • Quantitative imaging of magnetic induction of nanostructures in amorphous and cross-section samples.

  7. Time Dependent Tunneling in Laser Irradiated Scanning Tunneling Microscope Junction

    Science.gov (United States)

    Park, Sookyung Hur

    A principal motivation for the studies reported in this thesis was to obtain a theoretical explanation for the experimental results obtained by Nguyen et al. (1989) to determine the traversal time of an electron tunneling through a quantum mechanical barrier in a laser irradiated STM junction. The work therefore focused on the calculation of tunneling in a time-dependent oscillating barrier, and more specifically on the inelastic contributions to the tunneling current. To do so the kinetic formalism for tunneling was modified and extended to calculate inelastic processes in an irradiated tunneling junction. Furthermore, there is significant absorption of power from the laser beam in the junction electrodes resulting in thermal effects which can influence the tunneling. Extensive analysis of the spatial and temporal temperature distributions was first done for a realistic model of the diode emitter and anode using the Green function method. Specifically we considered (i) thermal effects due to surface heating of the absorbed laser radiation, (ii) the thermoelectric emf produced in the junction due to differential heating, and (iii) resistive and Thomson heat produced in the junction by laser induced currents. Using first-order time-dependent perturbation theory we also (iv) calculated the inelastic tunneling current due to a time dependent oscillating barrier produced by the antenna geometry of the STM junction. Lastly, we (v) formulated photo-assisted tunneling due to the electron -photon interaction in the junction using the second-quantization formalism. Although quite significant results were obtained for the tunneling current density as a function of frequency, gap distance and other junction parameters which gave insights into important features of the Nguyen et al. experiment (and tunneling characteristics of an irradiated STM in general), no single expression was derived or calculated results obtained which explains or fits all their observed data, or

  8. Scanning Ion Conductance Microscopy of Live Keratinocytes

    Science.gov (United States)

    Hegde, V.; Mason, A.; Saliev, T.; Smith, F. J. D.; McLean, W. H. I.; Campbell, P. A.

    2012-07-01

    Scanning ion conductance microscopy (SICM) is perhaps the least well known technique from the scanning probe microscopy (SPM) family of instruments. As with its more familiar counterpart, atomic force microscopy (AFM), the technique provides high-resolution topographic imaging, with the caveat that target structures must be immersed in a conducting solution so that a controllable ion current may be utilised as the basis for feedback. In operation, this non-contact characteristic of SICM makes it ideal for the study of delicate structures, such as live cells. Moreover, the intrinsic architecture of the instrument, incorporating as it does, a scanned micropipette, lends itself to combination approaches with complementary techniques such as patch-clamp electrophysiology: SICM therefore boasts the capability for both structural and functional imaging. For the present observations, an ICnano S system (Ionscope Ltd., Melbourn, UK) operating in 'hopping mode' was used, with the objective of assessing the instrument's utility for imaging live keratinocytes under physiological buffers. In scans employing cultured HaCaT cells (spontaneously immortalised, human keratinocytes), we compared the qualitative differences of live cells imaged with SICM and AFM, and also with their respective counterparts after chemical fixation in 4% paraformaldehyde. Characteristic surface microvilli were particularly prominent in live cell imaging by SICM. Moreover, time lapse SICM imaging on live cells revealed that changes in the pattern of microvilli could be tracked over time. By comparison, AFM imaging on live cells, even at very low contact forces (monitoring the most delicate living structures with attendant high spatial resolutions.

  9. Analysing magnetism using scanning SQUID microscopy.

    Science.gov (United States)

    Reith, P; Renshaw Wang, X; Hilgenkamp, H

    2017-12-01

    Scanning superconducting quantum interference device microscopy (SSM) is a scanning probe technique that images local magnetic flux, which allows for mapping of magnetic fields with high field and spatial accuracy. Many studies involving SSM have been published in the last few decades, using SSM to make qualitative statements about magnetism. However, quantitative analysis using SSM has received less attention. In this work, we discuss several aspects of interpreting SSM images and methods to improve quantitative analysis. First, we analyse the spatial resolution and how it depends on several factors. Second, we discuss the analysis of SSM scans and the information obtained from the SSM data. Using simulations, we show how signals evolve as a function of changing scan height, SQUID loop size, magnetization strength, and orientation. We also investigated 2-dimensional autocorrelation analysis to extract information about the size, shape, and symmetry of magnetic features. Finally, we provide an outlook on possible future applications and improvements.

  10. Scanning electron microscopy of superficial white onychomycosis*

    Science.gov (United States)

    de Almeida Jr., Hiram Larangeira; Boabaid, Roberta Oliveira; Timm, Vitor; Silva, Ricardo Marques e; de Castro, Luis Antonio Suita

    2015-01-01

    Superficial white onychomycosis is characterized by opaque, friable, whitish superficial spots on the nail plate. We examined an affected halux nail of a 20-year-old male patient with scanning electron microscopy. The mycological examination isolated Trichophyton mentagrophytes. Abundant hyphae with the formation of arthrospores were found on the nail's surface, forming small fungal colonies. These findings showed the great capacity for dissemination of this form of onychomycosis. PMID:26560225

  11. Scanning electron microscopy of molluscum contagiosum*

    OpenAIRE

    Almeida Jr,Hiram Larangeira de; Abuchaim,Martha Oliveira; Schneide, Maiko Abel; Marques, Leandra; Castro, Luis Antônio Suíta de

    2013-01-01

    Molluscum contagiosum is a disease caused by a poxvirus. It is more prevalent in children up to 5 years of age. There is a second peak of incidence in young adults. In order to examine its ultrastructure, three lesions were curetted without disruption, cut transversely with a scalpel, and routinely processed for scanning electron microscopy (SEM). The oval structure of molluscum contagiosum could be easily identified. In its core, there was a central umbilication and just below this depressio...

  12. Scanning electron microscopy of cold gases

    Science.gov (United States)

    Santra, Bodhaditya; Ott, Herwig

    2015-06-01

    Ultracold quantum gases offer unique possibilities to study interacting many-body quantum systems. Probing and manipulating such systems with ever increasing degree of control requires novel experimental techniques. Scanning electron microscopy is a high resolution technique which can be used for in situ imaging, single site addressing in optical lattices and precision density engineering. Here, we review recent advances and achievements obtained with this technique and discuss future perspectives.

  13. Measuring voltage transients with an ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1997-01-01

    We use an ultrafast scanning tunneling microscope to resolve propagating voltage transients in space and time. We demonstrate that the previously observed dependence of the transient signal amplitude on the tunneling resistance was only caused by the electrical sampling circuit. With a modified......-gating photoconductive switch with a rigidly attached fiber, the probe is scanned without changing the probe characteristics. (C) 1997 American Institute of Physics....

  14. Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy

    Directory of Open Access Journals (Sweden)

    Stephen A. Boppart

    2008-06-01

    Full Text Available Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT, utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR. In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR.

  15. In situ scanning tunnelling spectroscopy of inorganic transition metal complexes.

    Science.gov (United States)

    Albrecht, Tim; Moth-Poulsen, Kasper; Christensen, Jørn B; Guckian, Adrian; Bjørnholm, Thomas; Vos, Johannes G; Ulstrup, Jens

    2006-01-01

    Redox molecules with equilibrium potentials suitable for electrochemical control offer perspectives in nanoscale and single-molecule electronics. This applies to molecular but also towards higher sophistication such as transistor or diode function. Most recent nanoscale or single-molecule functional systems are, however, fraught with operational limitations such as cryogenic temperatures and ultra-high vacuum, or lack of electrochemical potential control. We report here cyclic voltammetry (CV) using single-crystal Au(111)- and Pt(111)-electrodes and electrochemical in situ scanning tunnelling microscopy (STM) of a class of Os(II)/(III)- and Co(II)/(III)-complexes, the former novel molecular electronics. The complexes are robust, with ligand groups suitable for linking the complexes to the Au(111)- and Pt(111)-surfaces via N- and S-donor atoms. The data reflect monolayer behaviour. Interfacial ET of the Os-complexes is fast, kET(0) > or = 10(6) s(-1), while the Co-complex reacts much more slowly, kET(0) approximately (1-3) x 10(3) s(-1). In STM of the Os-complexes shows a maximum in the tunnelling current/overpotential relation at constant bias voltage with up to 50-fold current rise. The peak position systematically the bias voltage and equilibrium potential, in keeping with theoretical frames for two-step electron transfer (ET) of in situ STM of redox molecules. The molecular conductivity behaves broadly similarly. The Co-complex also shows a tunnelling spectroscopic feature but much weaker than the Os-complexes. This can be ascribed much smaller interfacial ET rate constant, again caused by large intramolecular nuclear reorganization and weak electronic coupling to the substrate electrode. Overall the has mapped the properties of target molecules needed for stable electronic switching, possible importance in molecular electronics towards the single-molecule level, in room temperature condensed matter environment.

  16. Scanning Probe Microscopy of Organic Solar Cells

    Science.gov (United States)

    Reid, Obadiah G.

    Nanostructured composites of organic semiconductors are a promising class of materials for the manufacture of low-cost solar cells. Understanding how the nanoscale morphology of these materials affects their efficiency as solar energy harvesters is crucial to their eventual potential for large-scale deployment for primary power generation. In this thesis we describe the use of optoelectronic scanning-probe based microscopy methods to study this efficiency-structure relationship with nanoscale resolution. In particular, our objective is to make spatially resolved measurements of each step in the power conversion process from photons to an electric current, including charge generation, transport, and recombination processes, and correlate them with local device structure. We have achieved two aims in this work: first, to develop and apply novel electrically sensitive scanning probe microscopy experiments to study the optoelectronic materials and processes discussed above; and second, to deepen our understanding of the physics underpinning our experimental techniques. In the first case, we have applied conductive-, and photoconductive atomic force (cAFM & pcAFM) microscopy to measure both local photocurrent collection and dark charge transport properties in a variety of model and novel organic solar cell composites, including polymer/fullerene blends, and polymer-nanowire/fullerene blends, finding that local heterogeneity is the rule, and that improvements in the uniformity of specific beneficial nanostructures could lead to large increases in efficiency. We have used scanning Kelvin probe microscopy (SKPM) and time resolved-electrostatic force microscopy (trEFM) to characterize all-polymer blends, quantifying their sensitivity to photochemical degradation and the subsequent formation of local charge traps. We find that while trEFM provides a sensitive measure of local quantum efficiency, SKPM is generally unsuited to measurements of efficiency, less sensitive than tr

  17. A versatile high resolution scanning tunneling potentiometry implementation.

    Science.gov (United States)

    Druga, T; Wenderoth, M; Homoth, J; Schneider, M A; Ulbrich, R G

    2010-08-01

    We have developed a new scanning tunneling potentiometry technique which can-with only minor changes of the electronic setup-be easily added to any standard scanning tunneling microscope (STM). This extension can be combined with common STM techniques such as constant current imaging or scanning tunneling spectroscopy. It is capable of performing measurements of the electrochemical potential with microvolt resolution. Two examples demonstrate the versatile application. First of all, we have determined local variations of the electrochemical potential due to charge transport of biased samples down to angstrom length scales. Second, with tip and sample at different temperatures we investigated the locally varying thermovoltage occurring at the tunneling junction. Aside from its use in determining the chemical identity of substances at the sample surface our method provides a controlled way to eliminate the influence of laterally varying thermovoltages on low-bias constant current topographies.

  18. Chemical Phenomena of Atomic Force Microscopy Scanning.

    Science.gov (United States)

    Ievlev, Anton V; Brown, Chance; Burch, Matthew J; Agar, Joshua C; Velarde, Gabriel A; Martin, Lane W; Maksymovych, Petro; Kalinin, Sergei V; Ovchinnikova, Olga S

    2018-02-12

    Atomic force microscopy is widely used for nanoscale characterization of materials by scientists worldwide. The long-held belief of ambient AFM is that the tip is generally chemically inert but can be functionalized with respect to the studied sample. This implies that basic imaging and scanning procedures do not affect surface and bulk chemistry of the studied sample. However, an in-depth study of the confined chemical processes taking place at the tip-surface junction and the associated chemical changes to the material surface have been missing as of now. Here, we used a hybrid system that combines time-of-flight secondary ion mass spectrometry with an atomic force microscopy to investigate the chemical interactions that take place at the tip-surface junction. Investigations showed that even basic contact mode AFM scanning is able to modify the surface of the studied sample. In particular, we found that the silicone oils deposited from the AFM tip into the scanned regions and spread to distances exceeding 15 μm from the tip. These oils were determined to come from standard gel boxes used for the storage of the tips. The explored phenomena are important for interpreting and understanding results of AFM mechanical and electrical studies relying on the state of the tip-surface junction.

  19. Hollow-tip scanning photoelectron microscopy

    Science.gov (United States)

    Cherkun, A. P.; Mironov, B. N.; Aseyev, S. A.; Chekalin, S. V.

    2014-07-01

    A new type of microscopy based on scanning in vacuum by a beam of charged particles transmitted through a hollow probe has been implemented. This approach provides controllable motion of spatially localized ion, electron, molecular (atomic), and soft X-ray beams and investigation of the surface in the shear force mode. In the photoelectron mode, in which electrons are transmitted through a 2-μm quartz capillary, a surface profile of gadolinium irradiated by 400-nm femtosecond laser pulses has been visualized with a subwave spatial resolution. The new method of microscopy opens an opportunity of investigations in the field of nanometer local photodesorption of molecular ions (one of the last ideas of V.S. Letokhov).

  20. Soft stylus probes for scanning electrochemical microscopy.

    Science.gov (United States)

    Cortés-Salazar, Fernando; Träuble, Markus; Li, Fei; Busnel, Jean-Marc; Gassner, Anne-Laure; Hojeij, Mohamad; Wittstock, Gunther; Girault, Hubert H

    2009-08-15

    A soft stylus microelectrode probe has been developed to carry out scanning electrochemical microscopy (SECM) of rough, tilted, and large substrates in contact mode. It is fabricated by first ablating a microchannel in a polyethylene terephthalate thin film and filling it with a conductive carbon ink. After curing the carbon track and lamination with a polymer film, the V-shaped stylus was cut thereby forming a probe, with the cross section of the carbon track at the tip being exposed either by UV-photoablation machining or by blade cutting followed by polishing to produce a crescent moon-shaped carbon microelectrode. The probe properties have been assessed by cyclic voltammetry, approach curves, and line scans over electrochemically active and inactive substrates of different roughness. The influence of probe bending on contact mode imaging was then characterized using simple patterns. Boundary element method simulations were employed to rationalize the distance-dependent electrochemical response of the soft stylus probes.

  1. Differential-Concentration Scanning Ion Conductance Microscopy.

    Science.gov (United States)

    Perry, David; Page, Ashley; Chen, Baoping; Frenguelli, Bruno G; Unwin, Patrick R

    2017-11-21

    Scanning ion conductance microscopy (SICM) is a nanopipette-based scanning probe microscopy technique that utilizes the ionic current flowing between an electrode inserted inside a nanopipette probe containing electrolyte solution and a second electrode placed in a bulk electrolyte bath, to provide information on a substrate of interest. For most applications to date, the composition and concentration of the electrolyte inside and outside the nanopipette is identical, but it is shown herein that it can be very beneficial to lift this restriction. In particular, an ionic concentration gradient at the end of the nanopipette, generates an ionic current with a greatly reduced electric field strength, with particular benefits for live cell imaging. This differential concentration mode of SICM (ΔC-SICM) also enhances surface charge measurements and provides a new way to carry out reaction mapping measurements at surfaces using the tip for simultaneous delivery and sensing of the reaction rate. Comprehensive finite element method (FEM) modeling has been undertaken to enhance understanding of SICM as an electrochemical cell and to enable the interpretation and optimization of experiments. It is shown that electroosmotic flow (EOF) has much more influence on the nanopipette response in the ΔC-SICM configuration compared to standard SICM modes. The general model presented advances previous treatments, and it provides a framework for quantitative SICM studies.

  2. Phase-contrast scanning transmission electron microscopy.

    Science.gov (United States)

    Minoda, Hiroki; Tamai, Takayuki; Iijima, Hirofumi; Hosokawa, Fumio; Kondo, Yukihito

    2015-06-01

    This report introduces the first results obtained using phase-contrast scanning transmission electron microscopy (P-STEM). A carbon-film phase plate (PP) with a small center hole is placed in the condenser aperture plane so that a phase shift is introduced in the incident electron waves except those passing through the center hole. A cosine-type phase-contrast transfer function emerges when the phase-shifted scattered waves interfere with the non-phase-shifted unscattered waves, which passed through the center hole before incidence onto the specimen. The phase contrast resulting in P-STEM is optically identical to that in phase-contrast transmission electron microscopy that is used to provide high contrast for weak phase objects. Therefore, the use of PPs can enhance the phase contrast of the STEM images of specimens in principle. The phase shift resulting from the PP, whose thickness corresponds to a phase shift of π, has been confirmed using interference fringes displayed in the Ronchigram of a silicon single crystal specimen. The interference fringes were found to abruptly shift at the edge of the PP hole by π. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Scanning tunneling spectroscopy on electron-boson interactions in superconductors

    CERN Document Server

    Schackert, Michael Peter

    2015-01-01

    This work describes the experimental study of electron-boson interactions in superconductors by means of inelastic electron tunneling spectroscopy performed with a scanning tunneling microscope (STM) at temperatures below 1 K. This new approach allows the direct measurement of the Eliashberg function of conventional superconductors as demonstrated on lead (Pb) and niobium (Nb). Preparative experiments on unconventional iron-pnictides are presented in the end.

  4. Preparation of platinum/iridium scanning probe microscopy tips

    DEFF Research Database (Denmark)

    Sørensen, Alexis Hammer; Hvid, U.; Mortensen, M.W.

    1999-01-01

    material being etched is platinum/iridium (10%) the influence of the stop phase of the ac current terminating each pulse in the second etching is found to be negligible, while in the case of second etching of tungsten wires it is important to break the pulse in a certain phase to avoid formation of a thick...... of platinum from the wire surface and hereby give rise to "etching" of the wire. In the second etching blunt tips become sharp while tips which are already sharp apparently stay sharp. Therefore, the second etching scheme with pulses separated by pauses is found to be a very important factor...... for the production of sharp tips. After being etched the tips are ready for use in scanning tunneling microscopes, or they may be bent to form integrated tip/cantilever systems in ordinary commercial atomic force microscopes, being applicable as tapping mode tips and as electrostatic force microscopy tips. ©1999...

  5. Scanning Tunneling Microscopy, Atomic Force Microscopy, and Related Techniques

    Science.gov (United States)

    1992-02-26

    imaged the spiral structure, based on n-reverse turns, of the elastomeric wheat gluten proteins (D401). Masai et al. observed the sheet-type paracrystal 23...88, 68-71. (D402) Masai , J.; Shibata, T.; Kondo, S.; Isbiwata, S. J. Vac. Sci. Technol. B 1ŕ, 9, 1177-9. (D403) Heckl, W.M.; Smith, D.P.E.; Binnig, G

  6. 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.

  7. Angular Approach Scanning Ion Conductance Microscopy.

    Science.gov (United States)

    Shevchuk, Andrew; Tokar, Sergiy; Gopal, Sahana; Sanchez-Alonso, Jose L; Tarasov, Andrei I; Vélez-Ortega, A Catalina; Chiappini, Ciro; Rorsman, Patrik; Stevens, Molly M; Gorelik, Julia; Frolenkov, Gregory I; Klenerman, David; Korchev, Yuri E

    2016-05-24

    Scanning ion conductance microscopy (SICM) is a super-resolution live imaging technique that uses a glass nanopipette as an imaging probe to produce three-dimensional (3D) images of cell surface. SICM can be used to analyze cell morphology at nanoscale, follow membrane dynamics, precisely position an imaging nanopipette close to a structure of interest, and use it to obtain ion channel recordings or locally apply stimuli or drugs. Practical implementations of these SICM advantages, however, are often complicated due to the limitations of currently available SICM systems that inherited their design from other scanning probe microscopes in which the scan assembly is placed right above the specimen. Such arrangement makes the setting of optimal illumination necessary for phase contrast or the use of high magnification upright optics difficult. Here, we describe the designs that allow mounting SICM scan head on a standard patch-clamp micromanipulator and imaging the sample at an adjustable approach angle. This angle could be as shallow as the approach angle of a patch-clamp pipette between a water immersion objective and the specimen. Using this angular approach SICM, we obtained topographical images of cells grown on nontransparent nanoneedle arrays, of islets of Langerhans, and of hippocampal neurons under upright optical microscope. We also imaged previously inaccessible areas of cells such as the side surfaces of the hair cell stereocilia and the intercalated disks of isolated cardiac myocytes, and performed targeted patch-clamp recordings from the latter. Thus, our new, to our knowledge, angular approach SICM allows imaging of living cells on nontransparent substrates and a seamless integration with most patch-clamp setups on either inverted or upright microscopes, which would facilitate research in cell biophysics and physiology. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  8. 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.

  9. Investigating Single Molecule Physics with the Scanning Tunneling Microscope

    Science.gov (United States)

    Patel, Calvin Jay

    Scanning tunneling microscopy (STM) has given the scientific community a method to view, characterize, and manipulate the world at the atomic scale. Thirty years after the Nobel Prize in Physics was awarded for its invention, the remarkable instrument is still being used to deepen our understanding of physical and chemical processes. Tantamount to this has been the development of new techniques to expand its capabilities allowing STMs to answer increasingly more difficult scientific questions. This dissertation describes three technological thrusts in expanding the STMs capabilities in studying physics at the single molecule level. First, I have helped developed a new technique called the RF-STM which has the potential to snapshot femtosecond and picosecond processes by locking into the high frequency tunneling component generated from the 80MHz laser pulse train. This technique solves the problem of low frequency thermal oscillations when choppers are used in the beam line and if only tunneling signal is monitored, sub-angstrom spatial resolution should be simultaneously possible. Second, I have helped develop the itProbe technique by increasing its ability to map out the interaction potential energy surface (iPES) between a tip-CO molecule and a surface adsorbed molecule. I present a study conducted on the bridge-like 1,4 phenylene diisocyanide molecule where the iPES is probed at different heights and different energies. The result is an ability to 3-dimensionally map out the iPES and provide reliable insight into developing itProbe simulations. Third, I have developed a new technique called Energy Resolved Laser Action STM (ERLA-STM) where we can observe the change in molecular dynamics as a function of the illumination wavelength. In our pyrrolidine study, we demonstrated the kinetic changes that occur when an overtone of the CH stretch mode is excited by a near-IR laser pulse. By sweeping the excitation energy, we can characterize and control single molecule

  10. Tip preparation for usage in an ultra-low temperature UHV scanning tunneling microscope

    Directory of Open Access Journals (Sweden)

    S. Ernst, S. Wirth, M. Rams, V. Dolocan and F. Steglich

    2007-01-01

    Full Text Available This work deals with the preparation and characterization of tungsten tips for the use in UHV low-temperature scanning tunneling microscopy and spectroscopy (STM and STS, respectively. These specific environments require in situ facilities for tip conditioning, for further sharpening of the tips, as well as for reliable tip characterization. The implemented conditioning methods include direct resistive annealing, annealing by electron bombardment, and self-sputtering with noble gas ions. Moreover, results from in situ tip characterization by field emission and STM experiments were compared to ex situ scanning electron microscopy. Using the so-prepared tips, high resolution STM images and tunneling spectra were obtained in a temperature range from ambient down to 350 mK, partially with applied magnetic field, on a variety of materials.

  11. Electric field effects in scanning tunneling microscope imaging

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Quaade, Ulrich; Grey, Francois

    1998-01-01

    We present a high-voltage extension of the Tersoff-Hamann theory of scanning tunneling microscope (STM) images, which includes the effect of the electric field between the tip and the sample. The theoretical model is based on first-principles electronic structure calculations and has no adjustable...

  12. Photon scanning tunneling microscope in combination with a force microscope

    NARCIS (Netherlands)

    Moers, M.H.P.; Moers, M.H.P.; Tack, R.G.; van Hulst, N.F.; Bölger, B.; Bölger, B.

    1994-01-01

    The simultaneous operation of a photon scanning tunneling microscope with an atomic force microscope is presented. The use of standard atomic force silicon nitride cantilevers as near-field optical probes offers the possibility to combine the two methods. Vertical forces and torsion are detected

  13. Scanning tunneling spectroscopy on heavy-fermion systems; Rastertunnelspektroskopie an Schwere-Fermionen-Systemen

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, Stefan

    2011-06-24

    in the framework of this thesis different heavy-fermion systems were studied by means of scanning tunneling microscopy and spectroscopy. In the experiment two main topics existed. On the one hand the heavy-fermion superconductivity in the compounds CeCu{sub 2}Si{sub 2}, CeCoIn{sub 5}, and on the other hand the Kondo effect in the Kondo-lattice system YbRh{sub 2}Si{sub 2}.

  14. Seismic scanning tunneling macroscope - Elastic simulations and Arizona mine test

    KAUST Repository

    Hanafy, Sherif M.

    2012-01-01

    Elastic seismic simulations and field data tests are used to validate the theory of a seismic scanning tunneling macroscope (SSTM). For nearfield elastic simulation, the SSTM results show superresolution to be better than λ/8 if the only scattered data are used as input data. If the direct P and S waves are muted then the resolution of the scatterer locations are within about λ/5. Seismic data collected in an Arizona tunnel showed a superresolution limit of at least λ/19. These test results are consistent with the theory of the SSTM and suggest that the SSTM can be a tool used by geophysicists as a probe for near-field scatterers.

  15. Nanolithography on hydrogen terminateed silicon by scanning probe microscopy

    NARCIS (Netherlands)

    Schönenberger, Christian; Kramer, Niels; Kramer, N.

    1996-01-01

    Scanning-probe microscopes (SPM), i.e. the scanning-tunneling and force microscopes, can be used to locally oxidize hydrogen-terminated silicon and hydrogenated amorphous silicon. Because of its reliability and potential for pattern transfer, this lithography process has found great attention and

  16. Extension of Seismic Scanning Tunneling Macroscope to Elastic Waves

    KAUST Repository

    Tarhini, Ahmad

    2017-11-06

    The theory for the seismic scanning tunneling macroscope is extended from acoustic body waves to elastic body-wave propagation. We show that, similar to the acoustic case, near-field superresolution imaging from elastic body waves results from the O(1/R) term, where R is the distance between the source and near-field scatterer. The higher-order contributions R−n for n>1 are cancelled in the near-field region for a point source with normal stress.

  17. Scanning Tunneling Spectroscopy of Proximity Superconductivity in Epitaxial Multilayer Graphene

    OpenAIRE

    Natterer, Fabian D.; Ha, Jeonghoon; Baek, Hongwoo; Zhang, Duming; Cullen, William; Zhitenev, Nikolai B.; Kuk, Young; Stroscio, Joseph A.

    2016-01-01

    We report on spatial measurements of the superconducting proximity effect in epitaxial graphene induced by a graphene-superconductor interface. Superconducting aluminum films were grown on epitaxial multilayer graphene on SiC. The aluminum films were discontinuous with networks of trenches in the film morphology reaching down to exposed graphene terraces. Scanning tunneling spectra measured on the graphene terraces show a clear decay of the superconducting energy gap with increasing separatio...

  18. Extension of Seismic Scanning Tunneling Macroscope to Elastic Waves

    Science.gov (United States)

    Tarhini, Ahmad; Guo, Bowen; Dutta, Gaurav; Schuster, Gerard T.

    2017-11-01

    The theory for the seismic scanning tunneling macroscope is extended from acoustic body waves to elastic body-wave propagation. We show that, similar to the acoustic case, near-field superresolution imaging from elastic body waves results from the O(1/R) term, where R is the distance between the source and near-field scatterer. The higher-order contributions R^{-n} for n>1 are cancelled in the near-field region for a point source with normal stress.

  19. Scanning transmission electron microscopy imaging and analysis

    CERN Document Server

    Pennycook, Stephen J

    2011-01-01

    Provides the first comprehensive treatment of the physics and applications of this mainstream technique for imaging and analysis at the atomic level Presents applications of STEM in condensed matter physics, materials science, catalysis, and nanoscience Suitable for graduate students learning microscopy, researchers wishing to utilize STEM, as well as for specialists in other areas of microscopy Edited and written by leading researchers and practitioners

  20. Microscopic techniques bridging between nanoscale and microscale with an atomically sharpened tip - field ion microscopy/scanning probe microscopy/ scanning electron microscopy.

    Science.gov (United States)

    Tomitori, Masahiko; Sasahara, Akira

    2014-11-01

    Over a hundred years an atomistic point of view has been indispensable to explore fascinating properties of various materials and to develop novel functional materials. High-resolution microscopies, rapidly developed during the period, have taken central roles in promoting materials science and related techniques to observe and analyze the materials. As microscopies with the capability of atom-imaging, field ion microscopy (FIM), scanning tunneling microscopy (STM), atomic force microscopy (AFM) and transmission electron microscopy (TEM) can be cited, which have been highly evaluated as methods to ultimately bring forward the viewpoint of reductionism in materials science. On one hand, there have been difficulties to derive useful and practical information on large (micro) scale unique properties of materials using these excellent microscopies and to directly advance the engineering for practical materials. To make bridges over the gap between an atomic scale and an industrial engineering scale, we have to develop emergence science step-by-step as a discipline having hierarchical structures for future prospects by combining nanoscale and microscale techniques; as promising ways, the combined microscopic instruments covering the scale gap and the extremely sophisticated methods for sample preparation seem to be required. In addition, it is noted that spectroscopic and theoretical methods should implement the emergence science.Fundamentally, the function of microscope is to determine the spatial positions of a finite piece of material, that is, ultimately individual atoms, at an extremely high resolution with a high stability. To define and control the atomic positions, the STM and AFM as scanning probe microscopy (SPM) have successfully demonstrated their power; the technological heart of SPM lies in an atomically sharpened tip, which can be observed by FIM and TEM. For emergence science we would like to set sail using the tip as a base. Meanwhile, it is significant

  1. Optimal lens design and use in laser-scanning microscopy.

    NARCIS (Netherlands)

    Negrean, A.; Mansvelder, H.D.

    2014-01-01

    In laser-scanning microscopy often an off-the-shelf achromatic doublet is used as a scan lens which can reduce the available diffraction-limited field-of-view (FOV) by a factor of 3 and introduce chromatic aberrations that are scan angle dependent. Here we present several simple lens designs of

  2. Theory and feasibility tests for a seismic scanning tunnelling macroscope

    KAUST Repository

    Schuster, Gerard T.

    2012-09-01

    We propose a seismic scanning tunnelling macroscope (SSTM) that can detect subwavelength scatterers in the near-field of either the source or the receivers. Analytic formulas for the time reverse mirror (TRM) profile associated with a single scatterer model show that the spatial resolution limit to be, unlike the Abbe limit of λ/2, independent of wavelength and linearly proportional to the source-scatterer separation as long as the scatterer is in the near-field region. This means that, as the scatterer approaches the source, imaging of the scatterer with super-resolution can be achieved. Acoustic and elastic simulations support this concept, and a seismic experiment in an Arizona tunnel shows a TRM profile with super-resolution adjacent to the fault location. The SSTM is analogous to the optical scanning tunnelling microscopes having subwavelength resolution. Scaled to seismic frequencies, it is theoretically possible to extract 100 Hz information from 20 Hz data by the imaging of near-field seismic energy.

  3. Probing cytotoxicity of nanoparticles and organic compounds using scanning proton microscopy, scanning electron microscopy and fluorescence microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tong Yongpeng [Institute of Nuclear Techniques, Shenzhen University, Nanhai Avenue 3688, Shenzhen 518060 (China)], E-mail: yongpengt@yahoo.com.cn; Li Changming [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637457 (Singapore); Liang Feng [Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200025 (China); Chen Jianmin [Shenzhen Municipal Hospital for Chronic Disease Control and Prevention, Guangdong 518020 (China); Zhang Hong; Liu Guoqing; Sun Huibin [Institute of Nuclear Techniques, Shenzhen University, Nanhai Avenue 3688, Shenzhen 518060 (China); Luong, John H.T. [Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, H4P 2R2 (Canada)

    2008-12-15

    Scanning proton microscopy, scanning electron microscopy (SEM) and fluorescence microscopy have been used to probe the cytotoxicity effect of benzo[a]pyrene (BaP), ethidium bromide (EB) and nanoparticles (ZnO, Al{sub 2}O{sub 3} and TiO{sub 2}) on a T lymphoblastic leukemia Jurkat cell line. The increased calcium ion (from CaCl{sub 2}) in the culture medium stimulated the accumulation of BaP and EB inside the cell, leading to cell death. ZnO, Al{sub 2}O{sub 3} and TiO{sub 2} nanoparticles, however, showed a protective effect against these two organic compounds. Such inorganic nanoparticles complexed with BaP or EB which became less toxic to the cell. Fe{sub 2}O{sub 3} nanoparticles as an insoluble particle model scavenged by macrophage were investigated in rats. They were scavenged out of the lung tissue about 48 h after infection. This result suggest that some insoluble inorganic nanoparticles of PM (particulate matters) showed protective effects on organic toxins induced acute toxic effects as they can be scavenged by macrophage cells. Whereas, some inorganic ions such as calcium ion in PM may help environmental organic toxins to penetrate cell membrane and induce higher toxic effect.

  4. A first principles scanning tunneling potentiometry study of an opaque graphene grain boundary in the ballistic transport regime.

    Science.gov (United States)

    Bevan, Kirk H

    2014-10-17

    We report on a theoretical interpretation of scanning tunneling potentiometry (STP), formulated within the Keldysh non-equilibrium Green's function description of quantum transport. By treating the probe tip as an electron point source/sink, it is shown that this approach provides an intuitive bridge between existing theoretical interpretations of scanning tunneling microscopy and STP. We illustrate this through ballistic transport simulations of the potential drop across an opaque graphene grain boundary, where atomistic features are predicted that might be imaged through high resolution STP measurements. The relationship between the electrochemical potential profile measured and the electrostatic potential drop across such a nanoscale defect is also explored in this model system.

  5. Semiconductor topography in aqueous environments: Tunneling microscopy of chemomechanically polished (001) GaAs

    Science.gov (United States)

    Sonnenfeld, Richard; Schneir, J.; Drake, B.; Hansma, P. K.; Aspnes, D. E.

    1987-06-01

    Scanning tunneling microscopy (STM) of (001) GaAs samples immersed in aqueous solutions has been used to assess the effectiveness of a standard bromine-methanol chemomechanical polish to produce flat surfaces over length scales from 5 to 1000 nm. The STM images reveal irregular 100-nm features coexisting with large areas of average roughness of the order of a few nanometers. The precision, stability, and reproducibility of these images suggest that immersion STM could be used to study surface chemical processes in real time.

  6. Plant cell wall characterization using scanning probe microscopy techniques

    Science.gov (United States)

    Yarbrough, John M; Himmel, Michael E; Ding, Shi-You

    2009-01-01

    Lignocellulosic biomass is today considered a promising renewable resource for bioenergy production. A combined chemical and biological process is currently under consideration for the conversion of polysaccharides from plant cell wall materials, mainly cellulose and hemicelluloses, to simple sugars that can be fermented to biofuels. Native plant cellulose forms nanometer-scale microfibrils that are embedded in a polymeric network of hemicelluloses, pectins, and lignins; this explains, in part, the recalcitrance of biomass to deconstruction. The chemical and structural characteristics of these plant cell wall constituents remain largely unknown today. Scanning probe microscopy techniques, particularly atomic force microscopy and its application in characterizing plant cell wall structure, are reviewed here. We also further discuss future developments based on scanning probe microscopy techniques that combine linear and nonlinear optical techniques to characterize plant cell wall nanometer-scale structures, specifically apertureless near-field scanning optical microscopy and coherent anti-Stokes Raman scattering microscopy. PMID:19703302

  7. Plant cell wall characterization using scanning probe microscopy techniques

    Directory of Open Access Journals (Sweden)

    Himmel Michael E

    2009-08-01

    Full Text Available Abstract Lignocellulosic biomass is today considered a promising renewable resource for bioenergy production. A combined chemical and biological process is currently under consideration for the conversion of polysaccharides from plant cell wall materials, mainly cellulose and hemicelluloses, to simple sugars that can be fermented to biofuels. Native plant cellulose forms nanometer-scale microfibrils that are embedded in a polymeric network of hemicelluloses, pectins, and lignins; this explains, in part, the recalcitrance of biomass to deconstruction. The chemical and structural characteristics of these plant cell wall constituents remain largely unknown today. Scanning probe microscopy techniques, particularly atomic force microscopy and its application in characterizing plant cell wall structure, are reviewed here. We also further discuss future developments based on scanning probe microscopy techniques that combine linear and nonlinear optical techniques to characterize plant cell wall nanometer-scale structures, specifically apertureless near-field scanning optical microscopy and coherent anti-Stokes Raman scattering microscopy.

  8. A High Rigidity and Precision Scanning Tunneling Microscope with Decoupled XY and Z Scans

    Directory of Open Access Journals (Sweden)

    Xu Chen

    2017-01-01

    Full Text Available A new scan-head structure for the scanning tunneling microscope (STM is proposed, featuring high scan precision and rigidity. The core structure consists of a piezoelectric tube scanner of quadrant type (for XY scans coaxially housed in a piezoelectric tube with single inner and outer electrodes (for Z scan. They are fixed at one end (called common end. A hollow tantalum shaft is coaxially housed in the XY-scan tube and they are mutually fixed at both ends. When the XY scanner scans, its free end will bring the shaft to scan and the tip which is coaxially inserted in the shaft at the common end will scan a smaller area if the tip protrudes short enough from the common end. The decoupled XY and Z scans are desired for less image distortion and the mechanically reduced scan range has the superiority of reducing the impact of the background electronic noise on the scanner and enhancing the tip positioning precision. High quality atomic resolution images are also shown.

  9. A High Rigidity and Precision Scanning Tunneling Microscope with Decoupled XY and Z Scans.

    Science.gov (United States)

    Chen, Xu; Guo, Tengfei; Hou, Yubin; Zhang, Jing; Meng, Wenjie; Lu, Qingyou

    2017-01-01

    A new scan-head structure for the scanning tunneling microscope (STM) is proposed, featuring high scan precision and rigidity. The core structure consists of a piezoelectric tube scanner of quadrant type (for XY scans) coaxially housed in a piezoelectric tube with single inner and outer electrodes (for Z scan). They are fixed at one end (called common end). A hollow tantalum shaft is coaxially housed in the XY-scan tube and they are mutually fixed at both ends. When the XY scanner scans, its free end will bring the shaft to scan and the tip which is coaxially inserted in the shaft at the common end will scan a smaller area if the tip protrudes short enough from the common end. The decoupled XY and Z scans are desired for less image distortion and the mechanically reduced scan range has the superiority of reducing the impact of the background electronic noise on the scanner and enhancing the tip positioning precision. High quality atomic resolution images are also shown.

  10. Full information acquisition in scanning probe microscopy and spectroscopy

    Science.gov (United States)

    Jesse, Stephen; Belianinov, Alex; Kalinin, Sergei V.; Somnath, Suhas

    2017-04-04

    Apparatus and methods are described for scanning probe microscopy and spectroscopy based on acquisition of full probe response. The full probe response contains valuable information about the probe-sample interaction that is lost in traditional scanning probe microscopy and spectroscopy methods. The full probe response is analyzed post data acquisition using fast Fourier transform and adaptive filtering, as well as multivariate analysis. The full response data is further compressed to retain only statistically significant components before being permanently stored.

  11. Electronic properties of (Zn,CoO systems probed by scanning tunnelling spectroscopy

    Directory of Open Access Journals (Sweden)

    L. Moldovan

    2008-05-01

    Full Text Available The aim of this paper is to gain insight into theelectronic properties of (Zn,CoO system - a widebandgap Diluted Magnetic Semiconductors (DMSshowing room temperature (RT ferromagnetism undern-type doping conditions. On the experimental side, ultrahigh-vacuum scanning tunnelling microscopy andspectroscopy (STM and STS at variable temperature (Tare used to probe the local electronic structure of thesystem. It is presented the map of the local density ofstates (LDOS of polar ZnO surfaces. Then, it is possibleto decorate (incorporate Co atoms onto (into thesemiconductor.

  12. Further observations on cerebellar climbing fibers. A study by means of light microscopy, confocal laser scanning microscopy and scanning and transmission electron microscopy.

    Science.gov (United States)

    Castejón, O J; Castejón, H V; Alvarado, M V

    2000-12-01

    The intracortical pathways of climbing fibers were traced in several vertebrate cerebella using light microscopy, confocal laser scanning microscopy, scanning and transmission electron microscopy. They were identified as fine fibers up to 1(micron thick, with a characteristic crossing-over bifurcation pattern. Climbing fiber collaterals were tridimensionally visualized forming thin climbing fiber glomeruli in the granular layer. Confocal laser scanning microscopy revealed three types of collateral processes at the interface between granular and Purkinje cell layers. Scanning electron microscopy showed climbing fiber retrograde collaterals in the molecular layer. Asymmetric synaptic contacts of climbing fibers with Purkinje dendritic spines and stellate neuron dendrites were characterized by transmission electron microscopy. Correlative microscopy allowed us to obtain the basic three-dimensional morphological features of climbing fibers in several vertebrates and to show with more accuracy a higher degree of lateral collateralization of these fibers within the cerebellar cortex. The correlative microscopy approach provides new views in the cerebellar cortex information processing.

  13. Advanced electron microscopy of novel ferromagnetic materials and ferromagnet/oxide interfaces in magnetic tunnel junctions

    Science.gov (United States)

    Shi, Fengyuan

    We have studied novel ferromagnetic (FM) materials and FM electrode/tunnel barrier interfaces in magnetic tunnel junctions (MTJs) by advanced electron microscopy including scanning transmission electron microscopy (HRSTEM) and electron energy loss spectroscopy (EELS). MTJs are one of the prototypical spintronic devices, with applications in magnetic random access memory, sensors and read heads. The performance of MTJs depends on several factors, including the FM electrodes and the FM/tunnel barrier interfaces. Therefore, to realize the high performance of MTJs, we first need high quality ferromagnetic electrodes with high spin polarization. High-quality Fe3O4 and Fe4N electrodes with theoretically predicted -100% spin polarization were fabricated by various methods and investigated by HRSTEM and STEM EELS. The Fe3O4 and Fe4N thin films have low defect density and good crystallinity, but when integrated as electrodes in a MTJ, problems emerged. In a Fe4N/AlOx/Fe MTJ, the magnetoresistance was negative, but relatively small, due to a defective Fe 3O4 reaction layer formed at the Fe4N/tunnel barrier interface revealed by HRSTEM and EELS. The interfacial reaction layer was thin and discontinuous which made direct imaging difficult. Therefore, STEM EELS was used to map out the reaction layer. A Fe3O4 reaction layer was also found in a nominally symmetric CoFe/AlOx/CoFe MTJs after annealing, which also exhibited inverse TMR and a non-symmetric bias dependence. We also investigated the MTJs with the Heusler alloy Co2MnSi as one or both electrode and crystalline MgO as the tunnel barrier, which exhibit quite high TMR due to coherent tunneling. We showed that the Co2MnSi/MgO interface in these junctions is dominated by a configuration of a pure Mn plane bonded across the interface to O. This was the first observation of that interface termination. HRSTEM images also show that the fraction of MnMn/O interface termination increases with increasing Mn concentration in the CMS

  14. Optomechatronics Design and Control for Confocal Laser Scanning Microscopy

    NARCIS (Netherlands)

    Yoo, H.W.

    2015-01-01

    Confocal laser scanning microscopy (CLSM) is considered as one of the major advancements in microscopy in the last century and is widely accepted as a 3D fluorescence imaging tool for biological studies. For the emerging biological questions CLSM requires fast imaging to detect rapid biological

  15. Towards Automated Nanomanipulation under Scanning Electron Microscopy

    Science.gov (United States)

    Ye, Xutao

    Robotic Nanomaterial Manipulation inside scanning electron microscopes (SEM) is useful for prototyping functional devices and characterizing one-dimensional nanomaterial's properties. Conventionally, manipulation of nanowires has been performed via teleoperation, which is time-consuming and highly skill-dependent. Manual manipulation also has the limitation of low success rates and poor reproducibility. This research focuses on a robotic system capable of automated pick-place of single nanowires. Through SEM visual detection and vision-based motion control, the system transferred individual silicon nanowires from their growth substrate to a microelectromechanical systems (MEMS) device that characterized the nanowires' electromechanical properties. The performances of the nanorobotic pick-up and placement procedures were quantified by experiments. The system demonstrated automated nanowire pick-up and placement with high reliability. A software system for a load-lock-compatible nanomanipulation system is also designed and developed in this research.

  16. Postprocessing Algorithm for Driving Conventional Scanning Tunneling Microscope at Fast Scan Rates

    Directory of Open Access Journals (Sweden)

    Hao Zhang

    2017-01-01

    Full Text Available We present an image postprocessing framework for Scanning Tunneling Microscope (STM to reduce the strong spurious oscillations and scan line noise at fast scan rates and preserve the features, allowing an order of magnitude increase in the scan rate without upgrading the hardware. The proposed method consists of two steps for large scale images and four steps for atomic scale images. For large scale images, we first apply for each line an image registration method to align the forward and backward scans of the same line. In the second step we apply a “rubber band” model which is solved by a novel Constrained Adaptive and Iterative Filtering Algorithm (CIAFA. The numerical results on measurement from copper(111 surface indicate the processed images are comparable in accuracy to data obtained with a slow scan rate, but are free of the scan drift error commonly seen in slow scan data. For atomic scale images, an additional first step to remove line-by-line strong background fluctuations and a fourth step of replacing the postprocessed image by its ranking map as the final atomic resolution image are required. The resulting image restores the lattice image that is nearly undetectable in the original fast scan data.

  17. Vector sensor for scanning SQUID microscopy

    Science.gov (United States)

    Dang, Vu The; Toji, Masaki; Thanh Huy, Ho; Miyajima, Shigeyuki; Shishido, Hiroaki; Hidaka, Mutsuo; Hayashi, Masahiko; Ishida, Takekazu

    2017-07-01

    We plan to build a novel 3-dimensional (3D) scanning SQUID microscope with high sensitivity and high spatial resolution. In the system, a vector sensor consists of three SQUID sensors and three pick-up coils realized on a single chip. Three pick-up coils are configured in orthogonal with each other to measure the magnetic field vector of X, Y, Z components. We fabricated some SQUID chips with one uniaxial pick-up coil or three vector pick-up coils and carried out fundamental measurements to reveal the basic characteristics. Josephson junctions (JJs) of sensors are designed to have the critical current density J c of 320 A/cm2, and the critical current I c becomes 12.5 μA for the 2.2μm × 2.2μm JJ. We carefully positioned the three pickup coils so as to keep them at the same height at the centers of all three X, Y and Z coils. This can be done by arranging them along single line parallel to a sample surface. With the aid of multilayer technology of Nb-based fabrication, we attempted to reduce an inner diameter of the pickup coils to enhance both sensitivity and spatial resolution. The method for improving a spatial resolution of a local magnetic field image is to employ an XYZ piezo-driven scanner for controlling the positions of the pick-up coils. The fundamental characteristics of our SQUID sensors confirmed the proper operation of our SQUID sensors and found a good agreement with our design parameters.

  18. Fault detection by surface seismic scanning tunneling macroscope: Field test

    KAUST Repository

    Hanafy, Sherif M.

    2014-08-05

    The seismic scanning tunneling macroscope (SSTM) is proposed for detecting the presence of near-surface impedance anomalies and faults. Results with synthetic data are consistent with theory in that scatterers closer to the surface provide brighter SSTM profiles than those that are deeper. The SSTM profiles show superresolution detection if the scatterers are in the near-field region of the recording line. The field data tests near Gulf of Aqaba, Haql, KSA clearly show the presence of the observable fault scarp, and identify the subsurface presence of the hidden faults indicated in the tomograms. Superresolution detection of the fault is achieved, even when the 35 Hz data are lowpass filtered to the 5-10 Hz band.

  19. A high stability and repeatability electrochemical scanning tunneling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zhigang; Wang, Jihao; Lu, Qingyou, E-mail: qxl@ustc.edu.cn [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China); Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Hou, Yubin [High Magnetic Field Laboratory, Chinese Academy of Sciences and University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-12-15

    We present a home built electrochemical scanning tunneling microscope (ECSTM) with very high stability and repeatability. Its coarse approach is driven by a closely stacked piezo motor of GeckoDrive type with four rigid clamping points, which enhances the rigidity, compactness, and stability greatly. It can give high clarity atomic resolution images without sound and vibration isolations. Its drifting rates in XY and Z directions in solution are as low as 84 pm/min and 59 pm/min, respectively. In addition, repeatable coarse approaches in solution within 2 mm travel distance show a lateral deviation less than 50 nm. The gas environment can be well controlled to lower the evaporation rate of the cell, thus reducing the contamination and elongating the measurement time. Atomically resolved SO{sub 4}{sup 2−} image on Au (111) work electrode is demonstrated to show the performance of the ECSTM.

  20. Scanning Tunneling Spectroscopy of Proximity Superconductivity in Epitaxial Multilayer Graphene.

    Science.gov (United States)

    Natterer, Fabian D; Ha, Jeonghoon; Baek, Hongwoo; Zhang, Duming; Cullen, William; Zhitenev, Nikolai B; Kuk, Young; Stroscio, Joseph A

    2016-01-15

    We report on spatial measurements of the superconducting proximity effect in epitaxial graphene induced by a graphene-superconductor interface. Superconducting aluminum films were grown on epitaxial multilayer graphene on SiC. The aluminum films were discontinuous with networks of trenches in the film morphology reaching down to exposed graphene terraces. Scanning tunneling spectra measured on the graphene terraces show a clear decay of the superconducting energy gap with increasing separation from the graphene-aluminum edges. The spectra were well described by Bardeen-Cooper-Schrieffer (BCS) theory. The decay length for the superconducting energy gap in graphene was determined to be greater than 400 nm. Deviations in the exponentially decaying energy gap were also observed on a much smaller length scale of tens of nanometers.

  1. Scanning tunneling microscope with continuous flow cryostat sample cooling

    Energy Technology Data Exchange (ETDEWEB)

    Behler, S.; Rose, M.K.; Dunphy, J.C.; Ogletree, D.F.; Salmeron, M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Chapelier, C. [Departement de Recherche Fondamentale sur la Matiere Condensee, CEA/Grenoble, 38054 Grenoble Cedex 9 (France)

    1997-06-01

    We have constructed an ultrahigh vacuum scanning tunneling microscope (STM) for operation in the temperature range 20{endash}300 K. The design consists of a vibration isolated sample holder mounted on a continuous flow cryostat. By rotation and linear motion of the cryostat, the sample can be positioned in front of various surface preparation and analysis instruments contained in a single vacuum chamber. A lightweight beetle-type STM head is lowered from the top onto the sample by a linear manipulator. To minimize helium convection in the cryostat, the entire vacuum system, including a liquid helium storage Dewar, can be tilted by a few degrees perpendicular to the cryostat axis, which improves the operation. The performance of the instrument is demonstrated by atomically resolved images of the Pd(111) surface and adsorbed CO molecules. {copyright} {ital 1997 American Institute of Physics.}

  2. Scanning-tunneling-spectroscopy-directed design of tailored deep-blue emitters.

    Science.gov (United States)

    Sanning, Jan; Ewen, Pascal R; Stegemann, Linda; Schmidt, Judith; Daniliuc, Constantin G; Koch, Tobias; Doltsinis, Nikos L; Wegner, Daniel; Strassert, Cristian A

    2015-01-12

    Frontier molecular orbitals can be visualized and selectively set to achieve blue phosphorescent metal complexes. For this purpose, the HOMOs and LUMOs of tridentate Pt(II) complexes were measured using scanning tunneling microscopy and spectroscopy. The introduction of electron-accepting or -donating moieties enables independent tuning of the frontier orbital energies, and the measured HOMO-LUMO gaps are reproduced by DFT calculations. The energy gaps correlate with the measured and the calculated energies of the emissive triplet states and the experimental luminescence wavelengths. This synergetic interplay between synthesis, microscopy, and spectroscopy enabled the design and realization of a deep-blue triplet emitter. Finding and tuning the electronic "set screws" at molecular level constitutes a useful experimental method towards an in-depth understanding and rational design of optoelectronic materials with tailored excited state energies and defined frontier-orbital properties. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Applications of orientation mapping by scanning and transmission electron microscopy

    DEFF Research Database (Denmark)

    Juul Jensen, D.

    1997-01-01

    The potentials of orientation mapping techniques (in the following referred to as OIM) for studies of thermomechanical processes are analysed. Both transmission electron microscopy (TEM) and scanning electron microscopy (SEM) based OIM techniques are considered. Among the thermomechanical processes...... information is achieved when the results of OIM and these various techniques are combined. Examples hereof are given to illustrate the potentials of OIM techniques. Finally, limitations of TEM and SEM based OIM for specific applications are discussed....

  4. System and method for compressive scanning electron microscopy

    Science.gov (United States)

    Reed, Bryan W

    2015-01-13

    A scanning transmission electron microscopy (STEM) system is disclosed. The system may make use of an electron beam scanning system configured to generate a plurality of electron beam scans over substantially an entire sample, with each scan varying in electron-illumination intensity over a course of the scan. A signal acquisition system may be used for obtaining at least one of an image, a diffraction pattern, or a spectrum from the scans, the image, diffraction pattern, or spectrum representing only information from at least one of a select subplurality or linear combination of all pixel locations comprising the image. A dataset may be produced from the information. A subsystem may be used for mathematically analyzing the dataset to predict actual information that would have been produced by each pixel location of the image.

  5. Structural examination of lithium niobate ferroelectric crystals by combining scanning electron microscopy and atomic force microscopy

    Science.gov (United States)

    Efremova, P. V.; Ped'ko, B. B.; Kuznecova, Yu. V.

    2016-02-01

    The structure of lithium niobate single crystals is studied by a complex technique that combines scanning electron microscopy and atomic force microscopy. By implementing the piezoresponse force method on an atomic force microscope, the domain structure of lithium niobate crystals, which was not revealed without electron beam irradiation, is visualized

  6. Scanning electron microscopy-energy dispersive X-ray spectrometer ...

    African Journals Online (AJOL)

    The distribution of arsenic (As) and cadmium (Cd) in himematsutake was analyzed using scanning electron microscopy-energy dispersive X-ray spectrometer (SEM-EDX). The atomic percentage of the metals was confirmed by inductively coupled plasma-mass spectrometer (ICP-MS). Results show that the accumulation of ...

  7. Challenges of scanning hall microscopy using batch fabricated probes

    NARCIS (Netherlands)

    Hatakeyama, Kodai

    2016-01-01

    Scanning Hall probe microscopy is a widely used technique for quantitative high resolution imaging of magnetic stray fields. Up to now probes with nanometer spatial resolution have only been realized by electron beam lithography, which is a slow and expensive fabrication technique. In this thesis,

  8. Nanochannel alignment analysis by scanning transmission ion microscopy

    DEFF Research Database (Denmark)

    Rajta, I.; Gál, G.A.B.; Szilasi, S.Z.

    2010-01-01

    In this paper a study on the ion transmission ratio of a nanoporous alumina sample is presented. The sample was investigated by scanning transmission ion microscopy (STIM) with different beam sizes. The hexagonally close-packed AlO nanocapillary array, realized as a suspended membrane of 15 νm...

  9. Scanning electron microscopy of Dermatobia hominis reveals cutaneous anchoring features.

    Science.gov (United States)

    Möhrenschlager, Matthias; Mempel, Martin; Weichenmeier, Ingrid; Engst, Reinhard; Ring, Johannnes; Behrendt, Heidrun

    2007-10-01

    We report the case of a 45-year-old Caucasian woman suffering from cutaneous myiasis. With the use of scanning electron microscopy, we placed special focus on the mechanisms by which Dermatobia hominis can fasten securely within the human skin.

  10. Characterization of Polycaprolactone Films Biodeterioration by Scanning Electron Microscopy

    Czech Academy of Sciences Publication Activity Database

    Hrubanová, Kamila; Voberková, S.; Hermanová, S.; Krzyžánek, Vladislav

    2014-01-01

    Roč. 20, S3 (2014), s. 1950-1951 ISSN 1431-9276 R&D Projects: GA MŠk EE.2.3.20.0103; GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : polycaprolactone films * biodeterioration * scanning electron microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.877, year: 2014

  11. The Use Of Scanning Probe Microscopy To Investigate Crystal-Fluid Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Orme, C A; Giocondi, J L

    2007-04-16

    Over the past decade there has been a natural drive to extend the investigation of dynamic surfaces in fluid environments to higher resolution characterization tools. Various aspects of solution crystal growth have been directly visualized for the first time. These include island nucleation and growth using transmission electron microscopy and scanning tunneling microscopy; elemental step motion using scanning probe microscopy; and the time evolution of interfacial atomic structure using various diffraction techniques. In this lecture we will discuss the use of one such in situ method, scanning probe microscopy, as a means of measuring surface dynamics during crystal growth and dissolution. We will cover both practical aspects of imaging such as environmental control, fluid flow, and electrochemical manipulation, as well as the types of physical measurements that can be made. Measurements such as step motion, critical lengths, nucleation density, and step fluctuations, will be put in context of the information they provide about mechanistic processes at surfaces using examples from metal and mineral crystal growth.

  12. Scanning probe microscopy: instrumentation and applications on thin films and magnetic multilayers.

    Science.gov (United States)

    Karoutsos, Vagelis

    2009-12-01

    In this article we present a review on instrumentation and the modes of operation of a scanning probe microscope. In detail, we review the main techniques of Scanning Probe Microscopy (SPM), which are Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM), focusing our attention on the latter one. The AFM instrument provides information on the roughness and grain size of thin films. As an example we review recent results on two metallic thin film systems: thin Ag films deposited on glass, and Ni/Pt compositionally modulated multilayers deposited on glass, Si, and polyimide substrates. To show the validity of the grain size measurements, we compare the data with the ones resulting from X-ray diffraction (XRD) measurements. We show that the AFM results are reliable for grain diameters as small as 14 nm, which is approximately comparable to the tip radius. Finally, we deal with Magnetic Force Microscopy (MFM) results on Co/Pt and Co/Au multilayers. We observe perpendicularly magnetized domains. The domain configurations are correlated to the magnetization hysteresis curves.

  13. Cryo scanning electron microscopy of Plasmodium falciparum-infected erythrocytes.

    Science.gov (United States)

    Hempel, Casper

    2017-07-01

    Plasmodium falciparum invades erythrocytes as an essential part of their life cycle. While living inside erythrocytes, the parasite remodels the cell's intracellular organization as well as its outer surface. Late trophozoite-stage parasites and schizonts introduce numerous small protrusions on the erythrocyte surface, called knobs. Current methods for studying these knobs include atomic force microscopy and electron microscopy. Standard electron microscopy methods rely on chemical fixation and dehydration modifying cell size. Here, a novel method is presented using rapid freezing and scanning electron microscopy under cryogenic conditions allowing for high resolution and magnification of erythrocytes. This novel technique can be used for precise estimates of knob density and for studies on cytoadhesion. © 2017 APMIS. Published by John Wiley & Sons Ltd.

  14. Invited review article: A 10 mK scanning probe microscopy facility.

    Science.gov (United States)

    Song, Young Jae; Otte, Alexander F; Shvarts, Vladimir; Zhao, Zuyu; Kuk, Young; Blankenship, Steven R; Band, Alan; Hess, Frank M; Stroscio, Joseph A

    2010-12-01

    We describe the design, development and performance of a scanning probe microscopy (SPM) facility operating at a base temperature of 10 mK in magnetic fields up to 15 T. The microscope is cooled by a custom designed, fully ultra-high vacuum (UHV) compatible dilution refrigerator (DR) and is capable of in situ tip and sample exchange. Subpicometer stability at the tip-sample junction is achieved through three independent vibration isolation stages and careful design of the dilution refrigerator. The system can be connected to, or disconnected from, a network of interconnected auxiliary UHV chambers, which include growth chambers for metal and semiconductor samples, a field-ion microscope for tip characterization, and a fully independent additional quick access low temperature scanning tunneling microscope (STM) and atomic force microscope (AFM) system. To characterize the system, we present the cooling performance of the DR, vibrational, tunneling current, and tip-sample displacement noise measurements. In addition, we show the spectral resolution capabilities with tunneling spectroscopy results obtained on an epitaxial graphene sample resolving the quantum Landau levels in a magnetic field, including the sublevels corresponding to the lifting of the electron spin and valley degeneracies.

  15. Local potentiometry using a multiprobe scanning tunneling microscope.

    Science.gov (United States)

    Bannani, A; Bobisch, C A; Möller, R

    2008-08-01

    Scanning tunneling potentiometry (STP) is a powerful tool to analyze the conductance through thin conducting layers with lateral resolution in the nanometer range. In this work, we show how a commercial ultrahigh vacuum multiprobe system, equipped with four independent tips, can be used to perform STP experiments. Two tips are gently pushed into the surface applying a lateral current through the layer of interest. Simultaneously, the topography and the potential distribution across the metal film are measured with a third tip. The signal-to-noise ratio of the potentiometry signal may be enhanced by using a fourth tip, providing a reference potential in close vicinity of the studied area. Two different examples are presented. For epitaxial (111) oriented Bi films, grown on a Si(100)-(2 x 1) surface, an almost constant gradient of the potential as well as potential drops at individual Bi-domain boundaries were observed. On the surface of the Si(111)(3 x 3)-Ag superstructure the potential variation at individual monoatomic steps could be precisely resolved.

  16. Non-linear image scanning microscopy (Conference Presentation)

    Science.gov (United States)

    Gregor, Ingo; Ros, Robert; Enderlein, Jörg

    2017-02-01

    Nowadays, multiphoton microscopy can be considered as a routine method for the observation of living cells, organs, up to whole organisms. Second-harmonics generation (SHG) imaging has evolved to a powerful qualitative and label-free method for studying fibrillar structures, like collagen networks. However, examples of super-resolution non-linear microscopy are rare. So far, such approaches require complex setups and advanced synchronization of scanning elements limiting the image acquisition rates. We describe theory and realization of a super-resolution image scanning microscope [1, 2] using two-photon excited fluorescence as well as second-harmonic generation. It requires only minor modifications compared to a classical two-photon laser-scanning microscope and allows image acquisition at the high frame rates of a resonant galvo-scanner. We achieve excellent sensitivity and high frame-rate in combination with two-times improved lateral resolution. We applied this method to fixed cells, collagen hydrogels, as well as living fly embryos. Further, we proofed the excellent image quality of our setup for deep tissue imaging. 1. Müller C.B. and Enderlein J. (2010) Image scanning microscopy. Phys. Rev. Lett. 104(19), 198101. 2. Sheppard C.J.R. (1988) Super-resolution in confocal imaging. Optik (Stuttg) 80 53-54.

  17. Investigations in optoelectronic image processing in scanning laser microscopy

    Science.gov (United States)

    Chaliha, Hiranya Kumar

    A considerable amount of work has been done on scann-ing laser microscopy since its applications were first pointed out by Roberts and Young[1], Minsky [2] and Davidovits et al [3]. The advent of laser has made it possible to focus an intense beam of laser light in a scanning optical microscope (SOM) [4, 5] and hence explore regions of microscopy[6] uncovered by conven-tional microscopy. In the simple SOM [7, 8, 9], the upper spatial frequency in amplitude transmittance or reflectance of an object for which transfer function is nonzero is same as that in a conventional optical microscope. However, in Type II SOM [7] or confocal SOM that employs a coherent or a point detector, the spatial frequency bandwidth is twice that obtained in a conventional microscope. Besides this confocal set-up is found to be very useful in optical sectioning and consequently in 3-D image processing[10, 11, 12] specially of biological specimens. Such systems are also suitable for studies of semiconductor materials [13], super-resolution [14] and various imaginative ways of image processing[15, 16, 17] including phase imaging[18]. A brief survey of related advances in scanning optical microscopy has been covered in the chapter 1 of the thesis. The performance of SOM may be investigated by concent-rating also on signal derived by one dimensional scan of the object specimen. This simplified mode may also be adapted to give wealth of information for biological and semiconductor specimens. Hence we have investigated the design of a scanning laser system suited specifically for studies of line scan image signals of microscopic specimens when probed through a focused laser spot. An electro-mechanical method of scanning of the object specimen has been designed with this aim in mind. Chapter 2, Part A of the thesis deals with the design consider-ations of such a system. For analysis of scan signals at a later instant of time so as to facilitate further processing, an arrangement of microprocessor

  18. Surface morphology of Trichinella spiralis by scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C.W. (State Univ. of New York, Stony Brook); Ledbetter, M.C.

    1980-02-01

    The surface morphology of larval and adult Trichinella spiralis was studied by scanning electron microscopy (SEM) of fixed, dried, and metal-coated specimens. The results are compared with those found earlier by various investigators using light and transmission electron microscopy. Some morphological features reported here are revealed uniquely by SEM. These include the pores of the cephalic sense organs, the character of secondary cuticular folds, variations of the hypodermal gland cell openings or pores, and the presence of particles on the copulatory bell.

  19. Scanning conductance microscopy investigations on fixed human chromosomes

    DEFF Research Database (Denmark)

    Clausen, Casper Hyttel; Lange, Jacob Moresco; Jensen, Linda Boye

    2008-01-01

    Scanning conductance microscopy investigations were carried out in air on human chromosomes fixed on pre-fabricated SiO2 surfaces with a backgate. The point of the investigation was to estimate the dielectric constant of fixed human chromosomes in order to use it for microfluidic device...... optimization. The phase shift caused by the electrostatic forces, together with geometrical measurements of the atomic force microscopy (AFM) cantilever and the chromosomes were used to estimate a value,for the dielectric constant of different human chromosomes....

  20. Ultrafast Photon Counting Applied to Resonant Scanning STED Microscopy

    Science.gov (United States)

    Wu, Xundong; Toro, Ligia; Stefani, Enrico; Wu, Yong

    2014-01-01

    Summary To take full advantage of fast resonant scanning in super-resolution STimulated Emission Depletion (STED) microscopy, we have developed an ultrafast photon counting system based on a multi-giga-sample per second analog-to-digital conversion (ADC) chip that delivers an unprecedented 450 MHz pixel clock (2.2 ns pixel dwell time in each scan). The system achieves a large field of view (~50 × 50 μm) with fast scanning that reduces photobleaching, and advances the time-gated continuous wave (CW) STED technology to the usage of resonant scanning with hardware based time-gating. The assembled system provides superb signal-to-noise ratio and highly linear quantification of light that result in superior image quality. Also, the system design allows great flexibility in processing photon signals to further improve the dynamic range. In conclusion, we have constructed a frontier photon counting image acquisition system with ultrafast readout rate, excellent counting linearity, and with the capacity of realizing resonant-scanning CW-STED microscopy with on-line time-gated detection. PMID:25227160

  1. Combined nanoprobes for scanning probe microscopy: laser technology for processing and testing

    Science.gov (United States)

    Veiko, V. P.; Golubok, A. O.; Zuong, Z.; Varkentina, N. V.; Yakovlev, E. B.

    2008-02-01

    Scanning probe microscopy (SPM) is a high spatial resolution method of surface topography visualization and measurement of its local properties. The detecting of interaction arising between the sharp solid-state probe and the sample surface is the foundation of SPM. In dependence from nature of this interaction the scanning tunnel microscopy (STM), scanning force microscopy (SFM), scanning near field optical microscopy (SNOM), etc. are distinguished. The spatial resolution of all types of probe microscopy determins both sharpness of increasing of interaction between a probe and a sample at their approach, and shape and size of a top of a solid-state probe. So, the progress in SPM information capabilities is highly depends from probe properties and first of all from properly fabricated aperture size. Fabrication procedures are rather complicated because of nanometric scale size of aperture and hard requirements to reproducibility and need to be improved. The way how to do it is involving of feed-back in a processing procedure-results in two types of feedback for the process of drawing-out has been suggested, tested and installed into the technological set-up. Different probes have been fabricated by laser-assisted drawing-out during this work: SNOM types from optical fibers, micropipettes from quartz glass capillaries, micropipettes with microwires inside and with metallic covers outside. Some examples of application of above mentioned combined probes for cell membrane technology are described. Most important from them are topographical studying of cells and bacteria in living condition (in liquid) and studying of the mechanical properties of cell (rigidity of cell membrane) using the nanopipette as a tip of a force sensor. Also measurement of ion current that runs through cell membrane during its metabolic process using the nanopipette as well as in the well-known patch-clamp method have been done.

  2. Submolecular Electronic Mapping of Single Cysteine Molecules by in Situ Scanning Tunneling Imaging

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Chi, Qijin; Nazmutdinov, R. R.

    2009-01-01

    based on a slab model for the metal surface. The ordered monolayer offers a platform for submolecular scale electronic mapping that is an issue of fundamental interest but remains a challenge in STM imaging science and surface chemistry. Single Cys molecules were mapped as three electronic subunits......We have used L-Cysteine (Cys) as a model system to study the surface electronic structures of single molecules at the submolecular level in aqueous buffer solution by a combination of electrochemical scanning tunneling microscopy (in situ STM), electrochemistry including voltammetry...... contributed mainly from three chemical moieties: thiol (-SH), carboxylic (-COOH), and amine (-NH2) groups. The contrasts of the three subunits depend on the environment (e.g., pH), which affects the electronic structure of adsorbed species. From the DFT computations focused on single molecules, rational...

  3. Scanning tunneling spectroscopy of van der Waals graphene/semiconductor interfaces: absence of Fermi level pinning

    Science.gov (United States)

    Le Quang, T.; Cherkez, V.; Nogajewski, K.; Potemski, M.; Dau, M. T.; Jamet, M.; Mallet, P.; Veuillen, J.-Y.

    2017-09-01

    We have investigated the electronic properties of two-dimensional (2D) transition metal dichalcogenides (TMDs), namely trilayer WSe2 and monolayer MoSe2, deposited on epitaxial graphene on silicon carbide, by using scanning tunneling microscopy and spectroscopy (STM/STS) in ultra-high vacuum. Depending on the number of graphene layers below the TMD flakes, we identified variations in the electronic dI/dV(V) spectra measured by the STM tip: the most salient feature is a rigid shift of the TMD spectra (i.e. of the different band onset positions) towards occupied states by about 120 mV when passing from bilayer to monolayer underlying graphene. Since both graphene phases are metallic and present a work function difference in the same energy range, our measurements point towards the absence of Fermi-level pinning for such van der Waals 2D TMD/Metal heterojunctions, following the prediction of the Schottky-Mott model.

  4. Theoretical analysis of a dual-probe scanning tunneling microscope setup on graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen R.; Petersen, Dirch Hjorth

    2014-01-01

    Experimental advances allow for the inclusion of multiple probes to measure the transport properties of a sample surface. We develop a theory of dual-probe scanning tunneling microscopy using a Green's function formalism, and apply it to graphene. Sampling the local conduction properties at finite...... length scales yields real space conductance maps which show anisotropy for pristine graphene systems and quantum interference effects in the presence of isolated impurities. Spectral signatures in the Fourier transforms of real space conductance maps include characteristics that can be related...... to different scattering processes. We compute the conductance maps of graphene systems with different edge geometries or height fluctuations to determine the effects of nonideal graphene samples on dual-probe measurements. © 2014 American Physical Society....

  5. A correlative optical microscopy and scanning electron microscopy approach to locating nanoparticles in brain tumors.

    Science.gov (United States)

    Kempen, Paul J; Kircher, Moritz F; de la Zerda, Adam; Zavaleta, Cristina L; Jokerst, Jesse V; Mellinghoff, Ingo K; Gambhir, Sanjiv S; Sinclair, Robert

    2015-01-01

    The growing use of nanoparticles in biomedical applications, including cancer diagnosis and treatment, demands the capability to exactly locate them within complex biological systems. In this work a correlative optical and scanning electron microscopy technique was developed to locate and observe multi-modal gold core nanoparticle accumulation in brain tumor models. Entire brain sections from mice containing orthotopic brain tumors injected intravenously with nanoparticles were imaged using both optical microscopy to identify the brain tumor, and scanning electron microscopy to identify the individual nanoparticles. Gold-based nanoparticles were readily identified in the scanning electron microscope using backscattered electron imaging as bright spots against a darker background. This information was then correlated to determine the exact location of the nanoparticles within the brain tissue. The nanoparticles were located only in areas that contained tumor cells, and not in the surrounding healthy brain tissue. This correlative technique provides a powerful method to relate the macro- and micro-scale features visible in light microscopy with the nanoscale features resolvable in scanning electron microscopy. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Scanning tunnelling microscopy studies of cluster-surface interactions

    CERN Document Server

    Kenny, D J

    2001-01-01

    experiments revealed that the localised damage formed by cluster implantation can be significantly reversed at temperatures substantially lower (923 K) than the melting temperature of graphite (4450 K). The experimental results presented in this thesis explore the interaction of clusters with the graphite surface over three energy regimes of cluster deposition: low (thermal), intermediate and high energy. Thermal evaporation of C sub 6 sub 0 onto graphite initially results in the nucleation of islands, which subsequently grow to form thin films on the surface. It is demonstrated that the growth of such films is highly dependent upon the cleanliness of the surface and the temperature of the substrate during deposition. It is further suggested that the energetically favoured growth mode is that of an initial bi-layer in preference to a monolayer. Energetic deposition of Ag sub 7 sup - onto graphite is shown to result in the pinning of the cluster to the surface at intermediate energies (approx 300 eV) and impla...

  7. Scanning Tunneling Microscopy of 3-5 Semiconductors

    Science.gov (United States)

    1993-01-29

    thai the slab may be too thin . TABU HI. Calculated difference* in «ionic dJaplacemeau Alt (in A) ZnTe (ttO) surface for a su4aycr model min*» a tve...and 0. F. Sankey. Relaxation of the ZnTe and CuCi’(uS)’surf aces J. Vac. Sei. Technol. A 10, 2511-2514 (1992). (MS 275) M.-H. Tsai, C S. Chang, J...monocrystal- line films were grown on the Si-terminated (0001) surface of hexagonal a-SiC substrates hy the technique of chemi- cal vapor deposition

  8. Oxygen-free in situ scanning tunnelling microscopy

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Ulstrup, Jens

    2007-01-01

    containing organic molecule cysteamine and the biomolecule homocysteine. The third example is the iron-sulfur protein ferredoxin (Pyrococcus furiosus). Monolayers of these molecules on Au(111) are imaged to molecular resolution and the images compared in the presence and absence of oxygen. In all the cases...

  9. Spin-polarized scanning tunneling microscopy of magnetic nanostructures at the example of bcc-Co/Fe(110), Fe/Mo(110), and copper phthalocyanine/Fe(1110); Spinpolarisierte Rastertunnelmikroskopie magnetischer Nanostrukturen am Beispiel von bcc-Co/Fe(110), Fe/Mo(110) und Kupfer-Phthalocyanin/Fe(110)

    Energy Technology Data Exchange (ETDEWEB)

    Methfessel, Torsten

    2010-12-09

    This thesis provides an introduction into the technique of spin-polarized scanning tunnelling microscopy and spectroscopy as an experimental method for the investigation of magnetic nanostructures. Experimental results for the spin polarized electronic structure depending on the crystal structure of ultrathin Co layers, and depending on the direction of the magnetization for ultrathin Fe layers are presented. High-resolution measurements show the position-dependent spin polarization on a single copper-phthalocyanine molecule deposited on a ferromagnetic surface. Co was deposited by molecular beam epitaxy on the (110) surface of the bodycentered cubic metals Cr and Fe. In contrast to previous reports in the literature only two layers of Co can be stabilized in the body-centered cubic (bcc) structure. The bcc-Co films on the Fe(110) surface show no signs of epitaxial distortions. Thicker layers reconstruct into a closed-packed structure (hcp / fcc). The bcc structure increases the spin-polarization of Co to P=62 % in comparison to hcp-Co (P=45 %). The temperature-dependent spin-reorientation of ultrathin Fe/Mo(110) films was investigated by spin-polarized spectroscopy. A reorientation of the magnetic easy axis from the [110] direction along the surface normal to the in-plane [001] axis is observed at T (13.2{+-}0.5) K. This process can be identified as a discontinuous reorientation transition, revealing two simultaneous minima of the free energy in a certain temperature range. The electronic structure of mono- and double-layer Fe/Mo(110) shows a variation with the reorientation of the magnetic easy axis and with the direction of the magnetization. The investigation of the spin-polarized charge transport through a copper-phthalocyanine molecule on the Fe/Mo(110) surface provides an essential contribution to the understanding of spin-transport at the interface between metal and organic molecule. Due to the interaction with the surface of the metal the HOMO-LUMO energy

  10. [Advances of in vivo confocal scanning laser microscopy].

    Science.gov (United States)

    Tian, Ke-bin; Zhou, Guo-yu

    2006-02-01

    In vivo confocal scanning laser microscopy is being widely established as a time-saving, non-invasive, investigative methods in the study of body surfaces. Skin can be observed in its native state in vivo without the fixing, sectioning and staining that is necessary for routine histology. It is a new technology that can provide detailed images of tissue architecture and cellular morphology of living tissue. This paper reviews the fundamentals of in vivo confocal imaging and its clinical applications.

  11. Scanning Electron Microscopy of Cristispira Species in Chesapeake Bay Oysters

    OpenAIRE

    Tall, Ben D.; Nauman, Robert K.

    1981-01-01

    Scanning electron microscopy was employed to observe the physical interactions between Cristispira spp. and the crystalline style of the Chesapeake Bay oyster (Crassostrea virginica Gmelin 1791). Cristispira organisms were found associated with both the inner and outer layers of the posterior two-thirds of the style. The spirochetes possessed blunt-tipped ends, a cell diameter range of 0.6 to 0.8 μm, and distended spirochetal envelopes which followed the contour of the cells. Transmission ele...

  12. Playing peekaboo with graphene oxide: a scanning electrochemical microscopy investigation.

    Science.gov (United States)

    Rapino, Stefania; Treossi, Emanuele; Palermo, Vincenzo; Marcaccio, Massimo; Paolucci, Francesco; Zerbetto, Francesco

    2014-11-07

    Scanning electrochemical microscopy (SECM) can image graphene oxide (GO) flakes on insulating and conducting substrates. The contrast between GO and the substrate is controlled by the electrostatic interactions that are established between the charges of the molecular redox mediator and the charges present in the sheet/substrate. SECM also allows quantitative measurement - at the nano/microscale - of the charge transfer kinetics between single monolayer sheets and agent molecules.

  13. Scanning gate microscopy of ultra clean carbon nanotube quantum dots

    OpenAIRE

    Xue, Jiamin; Dhall, Rohan; Cronin, Stephen B.; LeRoy, Brian J.

    2015-01-01

    We perform scanning gate microscopy on individual suspended carbon nanotube quantum dots. The size and position of the quantum dots can be visually identified from the concentric high conductance rings. For the ultra clean devices used in this study, two new effects are clearly identified. Electrostatic screening creates non-overlapping multiple sets of Coulomb rings from a single quantum dot. In double quantum dots, by changing the tip voltage, the interactions between the quantum dots can b...

  14. Construction of a Dual-Tip Scanning Tunneling Microscope: a Prototype Nanotechnology Workstation.

    Science.gov (United States)

    Voelker, Mark Alan

    1993-01-01

    This dissertation describes the construction and performance of a dual-tip scanning tunneling microscope (STM). The microscope was built as a prototype nanotechnology workstation, a general purpose instrument designed to give a researcher the ability to investigate and manipulate nanometer scale structures. Chapter One describes the genesis and development of the concept of nanotechnology, from the atomic hypothesis of Democritus to modern developments in synthetic chemistry. Nanometer scale electronics (molecular electronics) is introduced and the state of the art in this field is described. The dual-tip scanning probe microscope is proposed as a way to address individual molecular electronic devices, a key goal in realizing nanometer scale electronic technology. Investigation of microtubules, a proposed nanometer scale intracellular biological information processing system, is also discussed. Chapter Two reviews the history and fundamental physics of STM, along with the related techniques of Field Ion Microscopy (FIM) and Ballistic Electon Emission Microscopy (BEEM). BEEM is used to introduce the physics of the dual -tip STM. Other dual-probe systems are also described. Chapter Three covers the design and construction of the dual-tip STM. Both hardware and software are described in detail. Chapter Four presents the results obtained with the dual-tip STM, including dual-tip images and noise measurements for the electronic circuitry. The last chapter, Chapter Five, contains suggested design changes for improving the performance of the dual -tip microscope and descriptions of experiments that can be performed with an improved instrument. Design and use of a nanotechnology workstation in the fields of semiconductor electronics, molecular electronics and cellular biology is discussed. Investigation of neurons grown on a silicon chip with a dual-tip STM system is proposed. Four Appendices present a noise model of the STM tunneling gap and preamplifier, describe

  15. Abrasion of 6 dentifrices measured by vertical scanning interference microscopy

    Science.gov (United States)

    PASCARETTI-GRIZON, Florence; MABILLEAU, Guillaume; CHAPPARD, Daniel

    2013-01-01

    Objectives The abrasion of dentifrices is well recognized to eliminate the dental plaque. The aims of this study were to characterize the abrasive powders of 6 dentifrices (3 toothpastes and 3 toothpowders) and to measure the abrasion on a test surface by Vertical Scanning Interference microscopy (VSI). Material and Methods Bright field and polarization microscopy were used to identify the abrasive particles on the crude dentifrices and after prolonged washes. Scanning electron microscopy and microanalysis characterized the shape and nature of the particles. Standardized and polished blocks of poly(methylmethacrylate) were brushed with a commercial electric toothbrush with the dentifrices. VSI quantified the mean roughness (Ra) and illustrated in 3D the abraded areas. Results Toothpastes induced a limited abrasion. Toothpowders induced a significantly higher roughness linked to the size of the abrasive particles. One powder (Gencix® produced a high abrasion when used with a standard testing weight. However, the powder is based on pumice particles covered by a plant homogenate that readily dissolves in water. When used in the same volume, or after dispersion in water, Ra was markedly reduced. Conclusion Light and electron microscopy characterize the abrasive particles and VSI is a new tool allowing the analysis of large surface of abraded materials. PMID:24212995

  16. Abrasion of 6 dentifrices measured by vertical scanning interference microscopy.

    Science.gov (United States)

    Pascaretti-Grizon, Florence; Mabilleau, Guillaume; Chappard, Daniel

    2013-01-01

    The abrasion of dentifrices is well recognized to eliminate the dental plaque. The aims of this study were to characterize the abrasive powders of 6 dentifrices (3 toothpastes and 3 toothpowders) and to measure the abrasion on a test surface by Vertical Scanning Interference microscopy (VSI). Bright field and polarization microscopy were used to identify the abrasive particles on the crude dentifrices and after prolonged washes. Scanning electron microscopy and microanalysis characterized the shape and nature of the particles. Standardized and polished blocks of poly(methylmethacrylate) were brushed with a commercial electric toothbrush with the dentifrices. VSI quantified the mean roughness (Ra) and illustrated in 3D the abraded areas. Toothpastes induced a limited abrasion. Toothpowders induced a significantly higher roughness linked to the size of the abrasive particles. One powder (Gencix® produced a high abrasion when used with a standard testing weight. However, the powder is based on pumice particles covered by a plant homogenate that readily dissolves in water. When used in the same volume, or after dispersion in water, Ra was markedly reduced. Light and electron microscopy characterize the abrasive particles and VSI is a new tool allowing the analysis of large surface of abraded materials.

  17. Analysis of leaf surfaces using scanning ion conductance microscopy.

    Science.gov (United States)

    Walker, Shaun C; Allen, Stephanie; Bell, Gordon; Roberts, Clive J

    2015-05-01

    Leaf surfaces are highly complex functional systems with well defined chemistry and structure dictating the barrier and transport properties of the leaf cuticle. It is a significant imaging challenge to analyse the very thin and often complex wax-like leaf cuticle morphology in their natural state. Scanning electron microscopy (SEM) and to a lesser extent Atomic force microscopy are techniques that have been used to study the leaf surface but their remains information that is difficult to obtain via these approaches. SEM is able to produce highly detailed and high-resolution images needed to study leaf structures at the submicron level. It typically operates in a vacuum or low pressure environment and as a consequence is generally unable to deal with the in situ analysis of dynamic surface events at submicron scales. Atomic force microscopy also possess the high-resolution imaging required and can follow dynamic events in ambient and liquid environments, but can over exaggerate small features and cannot image most leaf surfaces due to their inherent roughness at the micron scale. Scanning ion conductance microscopy (SICM), which operates in a liquid environment, provides a potential complementary analytical approach able to address these issues and which is yet to be explored for studying leaf surfaces. Here we illustrate the potential of SICM on various leaf surfaces and compare the data to SEM and atomic force microscopy images on the same samples. In achieving successful imaging we also show that SICM can be used to study the wetting of hydrophobic surfaces in situ. This has potentially wider implications than the study of leaves alone as surface wetting phenomena are important in a range of fundamental and applied studies. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  18. A 3-d laser scanning system and scan data processing method for the monitoring of tunnel deformations

    Science.gov (United States)

    Chmelina, Klaus; Jansa, Josef; Hesina, Gerd; Traxler, Christoph

    2012-11-01

    The paper presents the mobile multi-sensor system Orthos Plus for the monitoring and mapping of tunnel walls, a scan data processing method for the evaluation of 3-d tunnel wall displacements from subsequent wall scans and, finally, a virtual reality tool supporting the interpretation of data. The measuring system consists of a 3-d laser scanner, a motorised total station and a digital camera that are integrated on a light metal frame that is installed on a mobile platform. It has been designed to perform tunnel measurements most efficiently and to meet the special requirements of tunnels under construction. The evaluation of 3-d displacements is based on a 3-d matching algorithm that takes advantage of the particular conditions of tunnel (shotcrete) surfaces. The virtual reality tool allows viewing of data in a 3-d virtual reality tunnel model and their animation in time and space in order supports understanding in an optimal way. The measuring system Orthos Plus has been developed in the course of a national research project, the 3-d matching method in the frame of the Austrian Christian Doppler Laboratory Spatial Data from Laser Scanning and Remote Sensing and the VR tool in the Austrian COMET K1 Competence Center VRVis Center (www.vrvis.at).

  19. Temperature dependence of the superconducting proximity effect quantified by scanning tunneling spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Stępniak

    2015-01-01

    Full Text Available Here, we present the first systematic study on the temperature dependence of the extension of the superconducting proximity effect in a 1–2 atomic layer thin metallic film, surrounding a superconducting Pb island. Scanning tunneling microscopy/spectroscopy (STM/STS measurements reveal the spatial variation of the local density of state on the film from 0.38 up to 1.8 K. In this temperature range the superconductivity of the island is almost unaffected and shows a constant gap of a 1.20 ± 0.03 meV. Using a superconducting Nb-tip a constant value of the proximity length of 17 ± 3 nm at 0.38 and 1.8 K is found. In contrast, experiments with a normal conductive W-tip indicate an apparent decrease of the proximity length with increasing temperature. This result is ascribed to the thermal broadening of the occupation of states of the tip, and it does not reflect an intrinsic temperature dependence of the proximity length. Our tunneling spectroscopy experiments shed fresh light on the fundamental issue of the temperature dependence of the proximity effect for atomic monolayers, where the intrinsic temperature dependence of the proximity effect is comparably weak.

  20. Microvascular quantification based on contour-scanning photoacoustic microscopy

    Science.gov (United States)

    Yeh, Chenghung; Soetikno, Brian; Hu, Song; Maslov, Konstantin I.; Wang, Lihong V.

    2014-09-01

    Accurate quantification of microvasculature remains of interest in fundamental pathophysiological studies and clinical trials. Current photoacoustic microscopy can noninvasively quantify properties of the microvasculature, including vessel density and diameter, with a high spatial resolution. However, the depth range of focus (i.e., focal zone) of optical-resolution photoacoustic microscopy (OR-PAM) is often insufficient to encompass the depth variations of features of interest-such as blood vessels-due to uneven tissue surfaces. Thus, time-consuming image acquisitions at multiple different focal planes are required to maintain the region of interest in the focal zone. We have developed continuous three-dimensional motorized contour-scanning OR-PAM, which enables real-time adjustment of the focal plane to track the vessels' profile. We have experimentally demonstrated that contour scanning improves the signal-to-noise ratio of conventional OR-PAM by as much as 41% and shortens the image acquisition time by 3.2 times. Moreover, contour-scanning OR-PAM more accurately quantifies vessel density and diameter, and has been applied to studying tumors with uneven surfaces.

  1. Integrated Confocal and Scanning Probe Microscopy for Biomedical Research

    Directory of Open Access Journals (Sweden)

    B.J. Haupt

    2006-01-01

    Full Text Available Atomic force microscopy (AFM continues to be developed, not only in design, but also in application. The new focus of using AFM is changing from pure material to biomedical studies. More frequently, it is being used in combination with other optical imaging methods, such as confocal laser scanning microscopy (CLSM and fluorescent imaging, to provide a more comprehensive understanding of biological systems. To date, AFM has been used increasingly as a precise micromanipulator, probing and altering the mechanobiological characteristics of living cells and tissues, in order to examine specific, receptor-ligand interactions, material properties, and cell behavior. In this review, we discuss the development of this new hybrid AFM, current research, and potential applications in diagnosis and the detection of disease.

  2. High Resolution Helium Ion Scanning Microscopy of the Rat Kidney

    Science.gov (United States)

    Rice, William L.; Van Hoek, Alfred N.; Păunescu, Teodor G.; Huynh, Chuong; Goetze, Bernhard; Singh, Bipin; Scipioni, Larry; Stern, Lewis A.; Brown, Dennis

    2013-01-01

    Helium ion scanning microscopy is a novel imaging technology with the potential to provide sub-nanometer resolution images of uncoated biological tissues. So far, however, it has been used mainly in materials science applications. Here, we took advantage of helium ion microscopy to explore the epithelium of the rat kidney with unsurpassed image quality and detail. In addition, we evaluated different tissue preparation methods for their ability to preserve tissue architecture. We found that high contrast, high resolution imaging of the renal tubule surface is possible with a relatively simple processing procedure that consists of transcardial perfusion with aldehyde fixatives, vibratome tissue sectioning, tissue dehydration with graded methanol solutions and careful critical point drying. Coupled with the helium ion system, fine details such as membrane texture and membranous nanoprojections on the glomerular podocytes were visualized, and pores within the filtration slit diaphragm could be seen in much greater detail than in previous scanning EM studies. In the collecting duct, the extensive and striking apical microplicae of the intercalated cells were imaged without the shrunken or distorted appearance that is typical with conventional sample processing and scanning electron microscopy. Membrane depressions visible on principal cells suggest possible endo- or exocytotic events, and central cilia on these cells were imaged with remarkable preservation and clarity. We also demonstrate the use of colloidal gold probes for highlighting specific cell-surface proteins and find that 15 nm gold labels are practical and easily distinguishable, indicating that external labels of various sizes can be used to detect multiple targets in the same tissue. We conclude that this technology represents a technical breakthrough in imaging the topographical ultrastructure of animal tissues. Its use in future studies should allow the study of fine cellular details and provide

  3. High resolution helium ion scanning microscopy of the rat kidney.

    Science.gov (United States)

    Rice, William L; Van Hoek, Alfred N; Păunescu, Teodor G; Huynh, Chuong; Goetze, Bernhard; Singh, Bipin; Scipioni, Larry; Stern, Lewis A; Brown, Dennis

    2013-01-01

    Helium ion scanning microscopy is a novel imaging technology with the potential to provide sub-nanometer resolution images of uncoated biological tissues. So far, however, it has been used mainly in materials science applications. Here, we took advantage of helium ion microscopy to explore the epithelium of the rat kidney with unsurpassed image quality and detail. In addition, we evaluated different tissue preparation methods for their ability to preserve tissue architecture. We found that high contrast, high resolution imaging of the renal tubule surface is possible with a relatively simple processing procedure that consists of transcardial perfusion with aldehyde fixatives, vibratome tissue sectioning, tissue dehydration with graded methanol solutions and careful critical point drying. Coupled with the helium ion system, fine details such as membrane texture and membranous nanoprojections on the glomerular podocytes were visualized, and pores within the filtration slit diaphragm could be seen in much greater detail than in previous scanning EM studies. In the collecting duct, the extensive and striking apical microplicae of the intercalated cells were imaged without the shrunken or distorted appearance that is typical with conventional sample processing and scanning electron microscopy. Membrane depressions visible on principal cells suggest possible endo- or exocytotic events, and central cilia on these cells were imaged with remarkable preservation and clarity. We also demonstrate the use of colloidal gold probes for highlighting specific cell-surface proteins and find that 15 nm gold labels are practical and easily distinguishable, indicating that external labels of various sizes can be used to detect multiple targets in the same tissue. We conclude that this technology represents a technical breakthrough in imaging the topographical ultrastructure of animal tissues. Its use in future studies should allow the study of fine cellular details and provide

  4. High resolution helium ion scanning microscopy of the rat kidney.

    Directory of Open Access Journals (Sweden)

    William L Rice

    Full Text Available Helium ion scanning microscopy is a novel imaging technology with the potential to provide sub-nanometer resolution images of uncoated biological tissues. So far, however, it has been used mainly in materials science applications. Here, we took advantage of helium ion microscopy to explore the epithelium of the rat kidney with unsurpassed image quality and detail. In addition, we evaluated different tissue preparation methods for their ability to preserve tissue architecture. We found that high contrast, high resolution imaging of the renal tubule surface is possible with a relatively simple processing procedure that consists of transcardial perfusion with aldehyde fixatives, vibratome tissue sectioning, tissue dehydration with graded methanol solutions and careful critical point drying. Coupled with the helium ion system, fine details such as membrane texture and membranous nanoprojections on the glomerular podocytes were visualized, and pores within the filtration slit diaphragm could be seen in much greater detail than in previous scanning EM studies. In the collecting duct, the extensive and striking apical microplicae of the intercalated cells were imaged without the shrunken or distorted appearance that is typical with conventional sample processing and scanning electron microscopy. Membrane depressions visible on principal cells suggest possible endo- or exocytotic events, and central cilia on these cells were imaged with remarkable preservation and clarity. We also demonstrate the use of colloidal gold probes for highlighting specific cell-surface proteins and find that 15 nm gold labels are practical and easily distinguishable, indicating that external labels of various sizes can be used to detect multiple targets in the same tissue. We conclude that this technology represents a technical breakthrough in imaging the topographical ultrastructure of animal tissues. Its use in future studies should allow the study of fine cellular details

  5. High-resolution low-dose scanning transmission electron microscopy.

    Science.gov (United States)

    Buban, James P; Ramasse, Quentin; Gipson, Bryant; Browning, Nigel D; Stahlberg, Henning

    2010-01-01

    During the past two decades instrumentation in scanning transmission electron microscopy (STEM) has pushed toward higher intensity electron probes to increase the signal-to-noise ratio of recorded images. While this is suitable for robust specimens, biological specimens require a much reduced electron dose for high-resolution imaging. We describe here protocols for low-dose STEM image recording with a conventional field-emission gun STEM, while maintaining the high-resolution capability of the instrument. Our findings show that a combination of reduced pixel dwell time and reduced gun current can achieve radiation doses comparable to low-dose TEM.

  6. Evaluation of the bleached human enamel by Scanning Electron Microscopy

    DEFF Research Database (Denmark)

    Miranda, Carolina Baptista; Pagani, Clovis; Benetti, Ana Raquel

    2005-01-01

    Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning...... Electron Microscopy (SEM). Materials and Methods: Twenty intact human third molars extracted for orthodontic reasons were randomly divided into four groups (n=5) treated as follows: G1- storage in artificial saliva (control group); G2- four 30-minute applications of 35% carbamide peroxide (total exposure...

  7. [Pulmonary hydatidosis. Comparison of cytology and scanning electron microscopy].

    Science.gov (United States)

    Lavaud, F; Nou, J M; Sadrin, R; de Montreynaud, J M; Adnet, J J

    1986-01-01

    The puncture of a hydatid cyst with a fine needle is not generally recommended as a procedure and may even be contra-indicated in the first instance. Sometimes, however, the cytologist will be surprised to discover some scolices in the aspirate when the radiology is misleading, or not suggestive, and the serology is negative. We report two cases where the diagnosis was made by the cytological examination of the aspirate. The cytological study of the liquids was compared with electron microscopy scanning, enabling the stages of development of the parasite in the tissue of the pulmonary parenchyma to be assessed.

  8. Advanced Scanning Electron Microscopy and X Ray Microanalysis

    Science.gov (United States)

    Krinsley, David

    This text is the third in a group that evolved from a short course taught annually at Lehigh University, Bethlehem, Pa., since 1972. Chapters on magnetic contrast a nd electron channeling, dropped from the second volume for reasons of space, are included here along with new topics such as image processing. The first seven chapters should be oT value to those geologists interested in scanning electron microscopy (SEM) and microanalysis. Chapters 8 and 9, concerned with specimen preparation for biological SEM a nd cryomicroscopy, make up about one third of the text.

  9. Determining the resolution of scanning microwave impedance microscopy using atomic-precision buried donor structures

    Science.gov (United States)

    Scrymgeour, D. A.; Baca, A.; Fishgrab, K.; Simonson, R. J.; Marshall, M.; Bussmann, E.; Nakakura, C. Y.; Anderson, M.; Misra, S.

    2017-11-01

    To quantify the resolution limits of scanning microwave impedance microscopy (sMIM), we created scanning tunneling microscope (STM)-patterned donor nanostructures in silicon composed of 10 nm lines of highly conductive silicon buried under a protective top cap of silicon, and imaged them with sMIM. This dopant pattern is an ideal test of the resolution and sensitivity of the sMIM technique, as it is made with nm-resolution and offers minimal complications from topography convolution. It has been determined that typical sMIM tips can resolve lines down to ∼80 nm spacing, while resolution is independent of tip geometry as extreme tip wear does not change the resolving power, contrary to traditional scanning capacitance microscopy (SCM). Going forward, sMIM is an ideal technique for qualifying buried patterned devices, potentially allowing for quantitative post-fabrication characterization of donor structures, which may be an important tool for the study of atomic-scale transistors and state of the art quantum computation schemes.

  10. High-speed Lissajous-scan atomic force microscopy: Scan pattern planning and control design issues

    Science.gov (United States)

    Bazaei, A.; Yong, Yuen K.; Moheimani, S. O. Reza

    2012-06-01

    Tracking of triangular or sawtooth waveforms is a major difficulty for achieving high-speed operation in many scanning applications such as scanning probe microscopy. Such non-smooth waveforms contain high order harmonics of the scan frequency that can excite mechanical resonant modes of the positioning system, limiting the scan range and bandwidth. Hence, fast raster scanning often leads to image distortion. This paper proposes analysis and design methodologies for a nonlinear and smooth closed curve, known as Lissajous pattern, which allows much faster operations compared to the ordinary scan patterns. A simple closed-form measure is formulated for the image resolution of the Lissajous pattern. This enables us to systematically determine the scan parameters. Using internal model controllers (IMC), this non-raster scan method is implemented on a commercial atomic force microscope driven by a low resonance frequency positioning stage. To reduce the tracking errors due to actuator nonlinearities, higher order harmonic oscillators are included in the IMC controllers. This results in significant improvement compared to the traditional IMC method. It is shown that the proposed IMC controller achieves much better tracking performances compared to integral controllers when the noise rejection performances is a concern.

  11. Nanometrology using a through-focus scanning optical microscopy method

    Science.gov (United States)

    Attota, Ravikiran; Silver, Richard

    2011-02-01

    We present an initial review of a novel through-focus scanning optical microscopy (TSOM pronounced as 'tee-som') imaging method that produces nanometer-dimensional measurement sensitivity using a conventional bright-field optical microscope. In the TSOM method a target is scanned through the focus of an optical microscope, acquiring conventional optical images at different focal positions. The TSOM images are constructed using the through-focus optical images. A TSOM image is unique under given experimental conditions and is sensitive to changes in the dimensions of a target in a distinct way. We use this characteristic for nanoscale-dimensional metrology. This technique can be used to identify the dimension which is changing between two nanosized targets and to determine the dimensions using a library-matching method. This methodology has potential utility for a wide range of target geometries and application areas, including nanometrology, nanomanufacturing, defect analysis, inspection, process control and biotechnology.

  12. Quantitative phase imaging with scanning holographic microscopy: an experimental assessment.

    Science.gov (United States)

    Indebetouw, Guy; Tada, Yoshitaka; Leacock, John

    2006-11-28

    This paper demonstrates experimentally how quantitative phase information can be obtained in scanning holographic microscopy. Scanning holography can operate in both coherent and incoherent modes, simultaneously if desired, with different detector geometries. A spatially integrating detector provides an incoherent hologram of the object's intensity distribution (absorption and/or fluorescence, for example), while a point detector in a conjugate plane of the pupil provides a coherent hologram of the object's complex amplitude, from which a quantitative measure of its phase distribution can be extracted. The possibility of capturing simultaneously holograms of three-dimensional specimens, leading to three-dimensional reconstructions with absorption contrast, reflectance contrast, fluorescence contrast, as was previously demonstrated, and quantitative phase contrast, as shown here for the first time, opens up new avenues for multimodal imaging in biological studies.

  13. Quantitative single-molecule imaging by confocal laser scanning microscopy.

    Science.gov (United States)

    Vukojevic, Vladana; Heidkamp, Marcus; Ming, Yu; Johansson, Björn; Terenius, Lars; Rigler, Rudolf

    2008-11-25

    A new approach to quantitative single-molecule imaging by confocal laser scanning microscopy (CLSM) is presented. It relies on fluorescence intensity distribution to analyze the molecular occurrence statistics captured by digital imaging and enables direct determination of the number of fluorescent molecules and their diffusion rates without resorting to temporal or spatial autocorrelation analyses. Digital images of fluorescent molecules were recorded by using fast scanning and avalanche photodiode detectors. In this way the signal-to-background ratio was significantly improved, enabling direct quantitative imaging by CLSM. The potential of the proposed approach is demonstrated by using standard solutions of fluorescent dyes, fluorescently labeled DNA molecules, quantum dots, and the Enhanced Green Fluorescent Protein in solution and in live cells. The method was verified by using fluorescence correlation spectroscopy. The relevance for biological applications, in particular, for live cell imaging, is discussed.

  14. Elimination of periodic damped artifacts in scanning probe microscopy images

    Science.gov (United States)

    Chen, Yuhang; Huang, Wenhao

    2010-04-01

    When scanning probe microscopy (SPM) is operated at high scan rates, stripe-like artifacts will appear frequently in the SPM images. The removal of the image artifacts is highly demanded because they will distort the results in precise measurements. In this work, a method based on Prony analysis has been introduced to erase such periodic damped artifacts. Results demonstrate that this method prevails against the conventional fast Fourier transformation (FFT) method. Clean eliminations of the image artifacts are obtained, with almost no sacrifice of the detailed surface information. Even for arbitrary rough surfaces, the image artifacts can also be reduced by more than one order of magnitude. However, small amounts of stripes may still remain in the images. In these cases, the Prony analysis combined with locally weighted smoothing will provide better image quality. The artifacts reduction can have a meaning in the SPM-based visualization of dynamic phenomena with a nanoscale resolution.

  15. Quantitative phase imaging with scanning holographic microscopy: an experimental assesment

    Directory of Open Access Journals (Sweden)

    Tada Yoshitaka

    2006-11-01

    Full Text Available Abstract This paper demonstrates experimentally how quantitative phase information can be obtained in scanning holographic microscopy. Scanning holography can operate in both coherent and incoherent modes, simultaneously if desired, with different detector geometries. A spatially integrating detector provides an incoherent hologram of the object's intensity distribution (absorption and/or fluorescence, for example, while a point detector in a conjugate plane of the pupil provides a coherent hologram of the object's complex amplitude, from which a quantitative measure of its phase distribution can be extracted. The possibility of capturing simultaneously holograms of three-dimensional specimens, leading to three-dimensional reconstructions with absorption contrast, reflectance contrast, fluorescence contrast, as was previously demonstrated, and quantitative phase contrast, as shown here for the first time, opens up new avenues for multimodal imaging in biological studies.

  16. Interfacial scanning tunneling spectroscopy (STS) of chalcogenide/metal hybrid nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Saad, Mahmoud M.; Abdallah, Tamer [Physics Department, Faculty of Science, Ain Shams University, Abbassia, Cairo (Egypt); Easawi, Khalid; Negm, Sohair [Department of Physics and Mathematics, Faculty of Engineering (Shoubra), Benha University (Egypt); Talaat, Hassan, E-mail: hassantalaat@hotmail.com [Physics Department, Faculty of Science, Ain Shams University, Abbassia, Cairo (Egypt)

    2015-05-15

    Graphical abstract: - Highlights: • Comparing band gaps values obtained optically with STS. • Comparing direct imaging with calculated dimensions. • STS determination of the interfacial band bending of metal/chalcogenide. - Abstract: The electronic structure at the interface of chalcogenide/metal hybrid nanostructure (CdSe–Au tipped) had been studied by UHV scanning tunneling spectroscopy (STS) technique at room temperature. This nanostructure was synthesized by a phase transfer chemical method. The optical absorption of this hybrid nanostructure was recorded, and the application of the effective mass approximation (EMA) model gave dimensions that were confirmed by the direct measurements using the scanning tunneling microscopy (STM) as well as the high-resolution transmission electron microscope (HRTEM). The energy band gap obtained by STS agrees with the values obtained from the optical absorption. Moreover, the STS at the interface of CdSe–Au tipped hybrid nanostructure between CdSe of size about 4.1 ± 0.19 nm and Au tip of size about 3.5 ± 0.29 nm shows a band bending about 0.18 ± 0.03 eV in CdSe down in the direction of the interface. Such a result gives a direct observation of the electron accumulation at the interface of CdSe–Au tipped hybrid nanostructure, consistent with its energy band diagram. The presence of the electron accumulation at the interface of chalcogenides with metals has an important implication for hybrid nanoelectronic devices and the newly developed plasmon/chalcogenide photovoltaic solar energy conversion.

  17. Re-scan confocal microscopy (RCM) improves the resolution of confocal microscopy and increases the sensitivity

    Science.gov (United States)

    De Luca, Giulia; Breedijk, Ronald; Hoebe, Ron; Stallinga, Sjoerd; Manders, Erik

    2017-03-01

    Re-scan confocal microscopy (RCM) is a new super-resolution technique based on a standard confocal microscope extended with a re-scan unit in the detection path that projects the emitted light onto a sensitive camera. In this paper the fundamental properties of RCM, lateral resolution, axial resolution and signal-to-noise ratio, are characterized and compared with properties of standard confocal microscopy. The results show that the lateral resolution of RCM is ~170 nm compared to ~240 nm of confocal microscopy for 488 nm excitation and 1.49 NA. As the theory predicts, this improved lateral resolution is independent of the pinhole diameter. In standard confocal microscopy, the same lateral resolution can only be achieved with an almost closed pinhole and, consequently, with a major loss of signal. We show that the sectioning capabilities of the standard confocal microscope are preserved in RCM and that the axial resolution of RCM is slightly better (~15%) than the standard confocal microscope. Furthermore, the signal-to-noise ratio in RCM is a factor of 2 higher than in standard confocal microscopy, also due to the use of highly sensitive modern cameras. In case the pinhole of a confocal microscope is adjusted in such way that the lateral resolution is comparable to that of RCM, the signal-to-noise ratio in RCM is 4 times higher than standard confocal microscopy. Therefore, RCM offers a good alternative to standard confocal microscopy for higher lateral resolution with the main advantage of strongly improved sensitivity.

  18. Simultaneous Scanning Ion Conductance Microscopy and Atomic Force Microscopy with Microchanneled Cantilevers.

    Science.gov (United States)

    Ossola, Dario; Dorwling-Carter, Livie; Dermutz, Harald; Behr, Pascal; Vörös, János; Zambelli, Tomaso

    2015-12-04

    We combined scanning ion conductance microscopy (SICM) and atomic force microscopy (AFM) into a single tool using AFM cantilevers with an embedded microchannel flowing into the nanosized aperture at the apex of the hollow pyramid. An electrode was positioned in the AFM fluidic circuit connected to a second electrode in the bath. We could thus simultaneously measure the ionic current and the cantilever bending (in optical beam deflection mode). First, we quantitatively compared the SICM and AFM contact points on the approach curves. Second, we estimated where the probe in SICM mode touches the sample during scanning on a calibration grid and applied the finding to image a network of neurites on a Petri dish. Finally, we assessed the feasibility of a double controller using both the ionic current and the deflection as input signals of the piezofeedback. The experimental data were rationalized in the framework of finite elements simulations.

  19. 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.

  20. Two-color two-photon fluorescence laser scanning microscopy.

    Science.gov (United States)

    Quentmeier, S; Denicke, S; Gericke, K-H

    2009-11-01

    We present the first realization of a Two-Color Two-Photon Laser-Scanning Microscope (2c2pLSM) and UV fluorescence images of cells acquired with this technique. Fluorescence is induced by two-color two-photon absorption using the fundamental and the second harmonic of a Ti:Sa femtosecond laser. Simultaneous absorption of an 800 nm photon and a 400 nm photon energetically corresponds to one-photon absorption at 266 nm. This technique for Laser-Scanning Microscopy extends the excitation wavelength range of a Ti:Sa powered fluorescence microscope to the UV. In addition to the known advantages of multi-photon microscopy like intrinsic 3D resolution, reduced photo damage and high penetration depth 2c2pLSM offers the possibility of using standard high numeric aperture objectives for UV fluorescence imaging. The effective excitation wavelength of 266 nm corresponds especially well to the excitation spectrum of tryptophan. Hence, it is an ideal tool for label free fluorescence studies and imaging of intrinsic protein fluorescence which originates mainly from tryptophan. Thus a very sensitive natural lifetime probe can be used for monitoring protein reactions or changes in conformation. First measurements of living MIN-6 cells reveal differences between the UV fluorescence lifetimes of the nucleus and cytoplasm. The significance of this method was further demonstrated by monitoring the binding of biotin to avidin.

  1. Gold nanocone near-field scanning optical microscopy probes.

    Science.gov (United States)

    Fleischer, Monika; Weber-Bargioni, Alexander; Altoe, M Virginia P; Schwartzberg, Adam M; Schuck, P James; Cabrini, Stefano; Kern, Dieter P

    2011-04-26

    Near-field scanning optical microscopy enables the simultaneous topographical and subdiffraction limited optical imaging of surfaces. A process is presented for the implementation of single individually engineered gold cones at the tips of atomic force microscopy cantilevers. These cantilevers act as novel high-performance optical near-field probes. In the fabrication, thin-film metallization, electron beam induced deposition of etch masks, and Ar ion milling are combined. The cone constitutes a well-defined highly efficient optical antenna with a tip radius on the order of 10 nm and an adjustable plasmon resonance frequency. The sharp tip enables high resolution topographical imaging. By controllably varying the cone size, the resonance frequency can be adapted to the application of choice. Structural properties of these sharp-tipped probes are presented together with topographical images recorded with a cone probe. The antenna functionality is demonstrated by gathering the near-field enhanced Raman signature of individual carbon nanotubes with a gold cone scanning probe.

  2. Scanning ion microscopy with low energy lithium ions

    Energy Technology Data Exchange (ETDEWEB)

    Twedt, Kevin A. [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Maryland NanoCenter, University of Maryland, College Park, MD 20742 (United States); Chen, Lei [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); McClelland, Jabez J., E-mail: jabez.mcclelland@nist.gov [Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

    2014-07-01

    Using an ion source based on photoionization of laser-cooled lithium atoms, we have developed a scanning ion microscope with probe sizes of a few tens of nanometers and beam energies from 500 eV to 5 keV. These beam energies are much lower than the typical operating energies of the helium ion microscope or gallium focused ion beam systems. We demonstrate how low energy can be advantageous in ion microscopy when detecting backscattered ions, due to a decreased interaction volume and the potential for surface sensitive composition analysis. As an example application that demonstrates these advantages, we non-destructively image the removal of a thin residual resist layer during plasma etching in a nano-imprint lithography process. - Highlights: • We use an ion source based on photoionization of laser-cooled lithium atoms. • The ion source makes possible a low energy (500 eV to 5 keV) scanning ion microscope. • Low energy is preferred for ion microscopy with backscattered ions. • We use the microscope to image a thin resist used in nano-imprint lithography.

  3. Transient measurements with an ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1998-01-01

    the transmission line while the change in delay time between pump beam (on the sample) and probe beam (on the probe) provides the temporal information. The investigated photoconductor sample is a low-temperature-grown GaAs layer placed on a sapphire substrate with a thin, semitransparent gold layer. In tunneling...

  4. Confocal laser scanning microscopy in study of bone calcification

    Science.gov (United States)

    Nishikawa, Tetsunari; Kokubu, Mayu; Kato, Hirohito; Imai, Koichi; Tanaka, Akio

    2012-12-01

    Bone regeneration in mandible and maxillae after extraction of teeth or tumor resection and the use of rough surface implants in bone induction must be investigated to elucidate the mechanism of calcification. The calcified tissues are subjected to chemical decalcification or physical grinding to observe their microscopic features with light microscopy and transmission electron microscopy where the microscopic tissue morphology is significantly altered. We investigated the usefulness of confocal laser scanning microscopy (CLSM) for this purpose. After staggering the time of administration of calcein and alizarin red to experimental rats and dogs, rat alveolar bone and dog femur grafted with coral as scaffold or dental implants were observed with CLSM. In rat alveolar bone, the calcification of newly-formed bone and net-like canaliculi was observed at the mesial bone from the roots progressed at the rate of 15 μm/day. In dog femur grafted with coral, newly-formed bones along the space of coral were observed in an orderly manner. In dog femur with dental implants, after 8 weeks, newly-formed bone proceeded along the rough surface of the implants. CLSM produced high-magnification images of newly-formed bone and thin sections were not needed.

  5. Discretization of electronic states in large InAsP/InP multilevel quantum dots probed by scanning tunneling spectroscopy.

    Science.gov (United States)

    Fain, B; Robert-Philip, I; Beveratos, A; David, C; Wang, Z Z; Sagnes, I; Girard, J C

    2012-03-23

    The topography and the electronic structure of InAsP/InP quantum dots are probed by cross-sectional scanning tunneling microscopy and spectroscopy. The study of the local density of states in such large quantum dots confirms the discrete nature of the electronic levels whose wave functions are measured by differential conductivity mapping. Because of their large dimensions, the energy separation between the discrete electronic levels is low, allowing for quantization in both the lateral and growth directions as well as the observation of the harmonicity of the dot lateral potential.

  6. Scanning Tunneling Microscopic Observation of Adatom-Mediated Motifs on Gold-Thiol Self-assembled Monolayers at High Coverage

    DEFF Research Database (Denmark)

    Wang, Yun; Chi, Qijin; Hush, Noel S.

    2009-01-01

    Self-assembled monolayers (SAMs) formed by chemisorption of a branched-chain alkanethiol, 2-methyl-1-propanethiol, on Au(111) surfaces were studied by in situ scanning tunneling microscopy (STM) under electrochemical potential control and analyzed using extensive density functional theory (DFT...... the structural motifs observed on surfaces at low coverage and on gold nanoparticles to the observed spectroscopic properties of high-coverage SAMs formed by methanethiol. However, the significant role attributed to intermolecular steric packing effects suggests a lack of generality for the adatom-mediated motif...

  7. High-resolution characterization of multiferroic heterojunction using aberration-corrected scanning transmission electron microscopy

    Science.gov (United States)

    Yuan, Zhoushen; Ruan, Jieji; Xie, Lin; Pan, Xiaoqing; Wu, Di; Wang, Peng

    2017-04-01

    Multiferroic tunnel junctions have been considered as potential candidates for nonvolatile memory devices. Understanding the atomic structure at the interface is crucial for optimizing the performances in such oxide electronics. Spatially resolved electron energy loss spectroscopy (EELS) combined with aberration-corrected scanning transmission electron microscopy is employed to measure the compositional profiles across the interfaces of different layers with atomic resolution. Two-dimensional elemental imaging with atomic resolution is demonstrated, and the influences of the interface sharpness, the terminal layer, and cation intermixing are investigated. An asymmetric sublattice intermixing at the Pr0.8Ca0.2MnO3/BaTiO3/La0.7Sr0.3MnO3 interface is observed, which can affect the local Mn valence and coupling. The reduction in the Mn valence at the interface is further studied using EELS near-edge fine structures.

  8. Thirty per cent contrast in secondary-electron imaging by scanning field-emission microscopy.

    Science.gov (United States)

    Zanin, D A; De Pietro, L G; Peter, Q; Kostanyan, A; Cabrera, H; Vindigni, A; Bähler, Th; Pescia, D; Ramsperger, U

    2016-11-01

    We perform scanning tunnelling microscopy (STM) in a regime where primary electrons are field-emitted from the tip and excite secondary electrons out of the target-the scanning field-emission microscopy regime (SFM). In the SFM mode, a secondary-electron contrast as high as 30% is observed when imaging a monoatomic step between a clean W(110)- and an Fe-covered W(110)-terrace. This is a figure of contrast comparable to STM. The apparent width of the monoatomic step attains the 1 nm mark, i.e. it is only marginally worse than the corresponding width observed in STM. The origin of the unexpected strong contrast in SFM is the material dependence of the secondary-electron yield and not the dependence of the transported current on the tip-target distance, typical of STM: accordingly, we expect that a technology combining STM and SFM will highlight complementary aspects of a surface while simultaneously making electrons, selected with nanometre spatial precision, available to a macroscopic environment for further processing.

  9. Immunolabeling for scanning electron microscopy (SEM) and field emission SEM.

    Science.gov (United States)

    Goldberg, Martin W

    2008-01-01

    Scanning electron microscopy (SEM) is a high resolution surface imaging technique. Many biological process and structures occur at surfaces and if antibodies are available, their components can be located within the surface structure. This is usually done in a similar way to immuno-fluorescence, using an unconjugated primary antibody followed by a tagged secondary antibody against the primary. In this case the tag is usually a colloidal gold particle instead of a fluorophore. Therefore it is quite straightforward to adapt an immuno-fluorescence procedure for SEM, as long as certain precautions are followed, as discussed here. Progressing from immuno-fluorescence, which essentially only indicates the position of a protein within the volume of a cell, to immuno-SEM, puts the labeling into the context of cellular structures. The principles and practices of sample preparation, labeling and imaging are described here.

  10. Ultramicrosensors based on transition metal hexacyanoferrates for scanning electrochemical microscopy

    Directory of Open Access Journals (Sweden)

    Maria A. Komkova

    2013-10-01

    Full Text Available We report here a way for improving the stability of ultramicroelectrodes (UME based on hexacyanoferrate-modified metals for the detection of hydrogen peroxide. The most stable sensors were obtained by electrochemical deposition of six layers of hexacyanoferrates (HCF, more specifically, an alternating pattern of three layers of Prussian Blue and three layers of Ni–HCF. The microelectrodes modified with mixed layers were continuously monitored in 1 mM hydrogen peroxide and proved to be stable for more than 5 h under these conditions. The mixed layer microelectrodes exhibited a stability which is five times as high as the stability of conventional Prussian Blue-modified UMEs. The sensitivity of the mixed layer sensor was 0.32 A·M−1·cm−2, and the detection limit was 10 µM. The mixed layer-based UMEs were used as sensors in scanning electrochemical microscopy (SECM experiments for imaging of hydrogen peroxide evolution.

  11. Confocal laser scanning microscopy-guided surgery for neurofibroma.

    Science.gov (United States)

    Koller, S; Horn, M; Weger, W; Massone, C; Smolle, J; Gerger, A

    2009-12-01

    The neurofibromatoses comprise at least two separate genetic disorders with variable clinical features and an unpredictable course. The most common type, neurofibromatosis 1, is characterized by > or = 6 café-au-lait spots and the occurrence of neurofibromas, which may present as cutaneous, subcutaneous or plexiform lesions. Normally, excision of neurofibromas is only indicated in the presence of neurological symptoms, suspicion of malignancy or for exceptional cosmetic reasons. For a good functional and aesthetic result with the least danger of recurrence, the surgeon's goal is to excise as much tissue as necessary and as little tissue as possible. One of the main issues during the surgical procedure is to distinguish between neurofibroma and surrounding tissue. We report for the first time the use of confocal laser scanning microscopy to differentiate between neurofibroma and healthy skin.

  12. Cryo-Scanning Electron Microscopy of Captured Cirrus Ice Particles

    Science.gov (United States)

    Magee, N. B.; Boaggio, K.; Bandamede, M.; Bancroft, L.; Hurler, K.

    2016-12-01

    We present the latest collection of high-resolution cryo-scanning electron microscopy images and microanalysis of cirrus ice particles captured by high-altitude balloon (ICE-Ball, see abstracts by K. Boaggio and M. Bandamede). Ice particle images and sublimation-residues are derived from particles captured during approximately 15 balloon flights conducted in Pennsylvania and New Jersey over the past 12 months. Measurements include 3D digital elevation model reconstructions of ice particles, and associated statistical analyses of entire particles and particle sub-facets and surfaces. This 3D analysis reveals that morphologies of most ice particles captured deviate significantly from ideal habits, and display geometric complexity and surface roughness at multiple measureable scales, ranging from 100's nanometers to 100's of microns. The presentation suggests potential a path forward for representing scattering from a realistically complex array of ice particle shapes and surfaces.

  13. Local deposition of anisotropic nanoparticles using scanning electrochemical microscopy (SECM).

    Science.gov (United States)

    Fedorov, Roman G; Mandler, Daniel

    2013-02-28

    We demonstrate localized electrodeposition of anisotropic metal nanoobjects, namely Au nanorods (GNR), on indium tin oxide (ITO) using scanning electrochemical microscopy (SECM). A gold microelectrode was the source of the gold ions whereby double pulse chronoamperometry was employed to generate initially Au seeds which were further grown under controlled conditions. The distance between the microelectrode and the ITO surface as well as the different experimental parameters (electrodeposition regime, solution composition and temperature) were optimized to produce faceted gold seeds with the required characteristics (size and distribution). Colloidal chemical synthesis was successfully exploited for better understanding the role of the surfactant and different additives in breaking the crystallographic symmetry and anisotropic growth of GNR. Experiments performed in a conventional three-electrode cell revealed the most appropriate electrochemical conditions allowing high yield synthesis of nanorods with well-defined shape as well as nanocubes and bipyramids.

  14. Transient measurements with an ultrafast scanning tunneling microscope on semiconductor surfaces

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1998-01-01

    We demonstrate: the use of an ultrafast scanning tunneling microscope on a semiconductor surface. Laser-induced transient signals with 1.8 ps rise time are detected, The investigated sample is a low-temperature grown GaAs layer plated on a sapphire substrate with a thin gold layer that serves as st...... by the nonuniform carrier density created by the absorption of the light (photo Dember effect). The transient depends in sign and in shape on the direction of optical excitation. This signal is the dominating transient in tunneling mode. The signals are explained by a capacitive coupling across the tunneling gap...

  15. Three-Dimensional scanning transmission electron microscopy of biological specimens

    KAUST Repository

    De Jonge, Niels

    2010-01-18

    A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM). The specimen was a metallic replica of the biological structure comprising Pt nanoparticles 2-3 nm in diameter, with a high stability under electron beam radiation. The 3D dataset was processed by an automated deconvolution procedure. The lateral resolution was 1.1 nm, set by pixel size. Particles differing by only 10 nm in vertical position were identified as separate objects with greater than 20% dip in contrast between them. We refer to this value as the axial resolution of the deconvolution or reconstruction, the ability to recognize two objects, which were unresolved in the original dataset. The resolution of the reconstruction is comparable to that achieved by tilt-series transmission electron microscopy. However, the focal-series method does not require mechanical tilting and is therefore much faster. 3D STEM images were also recorded of the Golgi ribbon in conventional thin sections containing 3T3 cells with a comparable axial resolution in the deconvolved dataset. © 2010 Microscopy Society of America.

  16. 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.

  17. Amyloid Structure and Assembly: Insights from Scanning Transmission Electron Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Goldsbury, C.; Wall, J.; Baxa, U.; Simon, M. N.; Steven, A. C.; Engel, A.; Aebi, U.; Muller, S. A.

    2011-01-01

    Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).

  18. Scanning electron microscopy of the neuropathology of murine cerebral malaria

    Directory of Open Access Journals (Sweden)

    Brenneis Christian

    2006-11-01

    Full Text Available Abstract Background The mechanisms leading to death and functional impairments due to cerebral malaria (CM are yet not fully understood. Most of the knowledge about the pathomechanisms of CM originates from studies in animal models. Though extensive histopathological studies of the murine brain during CM are existing, alterations have not been visualized by scanning electron microscopy (SEM so far. The present study investigates the neuropathological features of murine CM by applying SEM. Methods C57BL/6J mice were infected with Plasmodium berghei ANKA blood stages. When typical symptoms of CM developed perfused brains were processed for SEM or light microscopy, respectively. Results Ultrastructural hallmarks were disruption of vessel walls, parenchymal haemorrhage, leukocyte sequestration to the endothelium, and diapedesis of macrophages and lymphocytes into the Virchow-Robin space. Villous appearance of observed lymphocytes were indicative of activated state. Cerebral oedema was evidenced by enlargement of perivascular spaces. Conclusion The results of the present study corroborate the current understanding of CM pathophysiology, further support the prominent role of the local immune system in the neuropathology of CM and might expose new perspectives for further interventional studies.

  19. Scanning electron microscopy physics of image formation and microanalysis

    CERN Document Server

    Reimer, Ludwig

    1985-01-01

    The aim of this book is to outline the physics of image formation, electron­ specimen interactions, imaging modes, the interpretation of micrographs and the use of quantitative modes "in scanning electron microscopy (SEM). lt forms a counterpart to Transmission Electron Microscopy (Vol. 36 of this Springer Series in Optical Sciences) . The book evolved from lectures delivered at the University of Münster and from a German text entitled Raster-Elektronenmikroskopie (Springer-Verlag), published in collaboration with my colleague Gerhard Pfefferkorn. In the introductory chapter, the principles of the SEM and of electron­ specimen interactions are described, the most important imaging modes and their associated contrast are summarized, and general aspects of eiemental analysis by x-ray and Auger electron emission are discussed. The electron gun and electron optics are discussed in Chap. 2 in order to show how an electron probe of small diameter can be formed, how the elec­ tron beam can be blanked at high fre...

  20. Water-Immersible MEMS scanning mirror designed for wide-field fast-scanning photoacoustic microscopy

    Science.gov (United States)

    Yao, Junjie; Huang, Chih-Hsien; Martel, Catherine; Maslov, Konstantin I.; Wang, Lidai; Yang, Joon-Mo; Gao, Liang; Randolph, Gwendalyn; Zou, Jun; Wang, Lihong V.

    2013-03-01

    By offering images with high spatial resolution and unique optical absorption contrast, optical-resolution photoacoustic microscopy (OR-PAM) has gained increasing attention in biomedical research. Recent developments in OR-PAM have improved its imaging speed, but have sacrificed either the detection sensitivity or field of view or both. We have developed a wide-field fast-scanning OR-PAM by using a water-immersible MEMS scanning mirror (MEMS-ORPAM). Made of silicon with a gold coating, the MEMS mirror plate can reflect both optical and acoustic beams. Because it uses an electromagnetic driving force, the whole MEMS scanning system can be submerged in water. In MEMS-ORPAM, the optical and acoustic beams are confocally configured and simultaneously steered, which ensures uniform detection sensitivity. A B-scan imaging speed as high as 400 Hz can be achieved over a 3 mm scanning range. A diffraction-limited lateral resolution of 2.4 μm in water and a maximum imaging depth of 1.1 mm in soft tissue have been experimentally determined. Using the system, we imaged the flow dynamics of both red blood cells and carbon particles in a mouse ear in vivo. By using Evans blue dye as the contrast agent, we also imaged the flow dynamics of lymphatic vessels in a mouse tail in vivo. The results show that MEMS-OR-PAM could be a powerful tool for studying highly dynamic and time-sensitive biological phenomena.

  1. Confocal laser scanning microscopy in study of bone calcification

    Energy Technology Data Exchange (ETDEWEB)

    Nishikawa, Tetsunari, E-mail: tetsu-n@cc.osaka-dent.ac.jp [Department of Oral Pathology, Osaka Dental University, Osaka (Japan); Kokubu, Mayu; Kato, Hirohito [Department of Oral Pathology, Osaka Dental University, Osaka (Japan); Imai, Koichi [Department of Biomaterials, Osaka Dental University, Osaka (Japan); Tanaka, Akio [Department of Oral Pathology, Osaka Dental University, Osaka (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer High-magnification images with depth selection, and thin sections were observed using CLSM. Black-Right-Pointing-Pointer The direction and velocity of calcification of the bone was observed by administration of 2 fluorescent dyes. Black-Right-Pointing-Pointer In dog femora grafted with coral blocks, newly-formed bone was observed in the coral block space with a rough surface. Black-Right-Pointing-Pointer Twelve weeks after dental implant was grafted in dog femora, the space between screws was filled with newly-formed bones. - Abstract: Bone regeneration in mandible and maxillae after extraction of teeth or tumor resection and the use of rough surface implants in bone induction must be investigated to elucidate the mechanism of calcification. The calcified tissues are subjected to chemical decalcification or physical grinding to observe their microscopic features with light microscopy and transmission electron microscopy where the microscopic tissue morphology is significantly altered. We investigated the usefulness of confocal laser scanning microscopy (CLSM) for this purpose. After staggering the time of administration of calcein and alizarin red to experimental rats and dogs, rat alveolar bone and dog femur grafted with coral as scaffold or dental implants were observed with CLSM. In rat alveolar bone, the calcification of newly-formed bone and net-like canaliculi was observed at the mesial bone from the roots progressed at the rate of 15 {mu}m/day. In dog femur grafted with coral, newly-formed bones along the space of coral were observed in an orderly manner. In dog femur with dental implants, after 8 weeks, newly-formed bone proceeded along the rough surface of the implants. CLSM produced high-magnification images of newly-formed bone and thin sections were not needed.

  2. Computer vision distortion correction of scanning probe microscopy images.

    Science.gov (United States)

    Gaponenko, Iaroslav; Tückmantel, Philippe; Ziegler, Benedikt; Rapin, Guillaume; Chhikara, Manisha; Paruch, Patrycja

    2017-04-06

    Since its inception, scanning probe microscopy (SPM) has established itself as the tool of choice for probing surfaces and functionalities at the nanoscale. Although recent developments in the instrumentation have greatly improved the metrological aspects of SPM, it is still plagued by the drifts and nonlinearities of the piezoelectric actuators underlying the precise nanoscale motion. In this work, we present an innovative computer-vision-based distortion correction algorithm for offline processing of functional SPM measurements, allowing two images to be directly overlaid with minimal error - thus correlating position with time evolution and local functionality. To demonstrate its versatility, the algorithm is applied to two very different systems. First, we show the tracking of polarisation switching in an epitaxial Pb(Zr0.2Ti0.8)O3 thin film during high-speed continuous scanning under applied tip bias. Thanks to the precise time-location-polarisation correlation we can extract the regions of domain nucleation and track the motion of domain walls until the merging of the latter in avalanche-like events. Secondly, the morphology of surface folds and wrinkles in graphene deposited on a PET substrate is probed as a function of applied strain, allowing the relaxation of individual wrinkles to be tracked.

  3. Scanning X-ray microscopy of superconductor/ferromagnet bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Stahl, Claudia; Ruoss, Stephen; Weigand, Markus; Schuetz, Gisela [Max Planck Institute for Intelligent Systems, Stuttgart (Germany); Zahn, Patrick; Bayer, Jonas [Max Planck Institute for Intelligent Systems, Stuttgart (Germany); Research Institute for Innovative Surfaces, FINO, Aalen University (Germany); Albrecht, Joachim [Research Institute for Innovative Surfaces, FINO, Aalen University (Germany)

    2016-07-01

    The magnetic flux distribution arising from a high-T{sub c} superconductor is detected and visualized with high spatial resolution using scanning x-ray microscopy (SXM). Therefore, we introduce a sensor layer, namely, an amorphous, soft-magnetic CoFeB cover layer. The magnetic stray fields of the supercurrents lead to a local reorientation of the magnetic moments in the ferromagnet, which is visualized using the large x-ray magnetic circular dichroism (XMCD) effect of the Co and Fe L3-edge. We show that the XMCD contrast in the sensor layer corresponds to the in-plane magnetic flux distribution of the superconductor and can hence be used to image magnetic structures in superconductors with high spatial resolution. Using the total electron yield (TEY) mode the surface structure and the magnetic domains can be imaged simultaneously and can be correlated. The measurements are carried out at our scanning x-ray microscope MAXYMUS at Bessy II, Berlin with the new low temperature setup.

  4. Post-processing strategies in image scanning microscopy.

    Science.gov (United States)

    McGregor, J E; Mitchell, C A; Hartell, N A

    2015-10-15

    Image scanning microscopy (ISM) coupled with pixel reassignment offers a resolution improvement of √2 over standard widefield imaging. By scanning point-wise across the specimen and capturing an image of the fluorescent signal generated at each scan position, additional information about specimen structure is recorded and the highest accessible spatial frequency is doubled. Pixel reassignment can be achieved optically in real time or computationally a posteriori and is frequently combined with the use of a physical or digital pinhole to reject out of focus light. Here, we simulate an ISM dataset using a test image and apply standard and non-standard processing methods to address problems typically encountered in computational pixel reassignment and pinholing. We demonstrate that the predicted improvement in resolution is achieved by applying standard pixel reassignment to a simulated dataset and explore the effect of realistic displacements between the reference and true excitation positions. By identifying the position of the detected fluorescence maximum using localisation software and centring the digital pinhole on this co-ordinate before scaling around translated excitation positions, we can recover signal that would otherwise be degraded by the use of a pinhole aligned to an inaccurate excitation reference. This strategy is demonstrated using experimental data from a multiphoton ISM instrument. Finally we investigate the effect that imaging through tissue has on the positions of excitation foci at depth and observe a global scaling with respect to the applied reference grid. Using simulated and experimental data we explore the impact of a globally scaled reference on the ISM image and, by pinholing around the detected maxima, recover the signal across the whole field of view. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Development of a 3D modeling algorithm for tunnel deformation monitoring based on terrestrial laser scanning

    Directory of Open Access Journals (Sweden)

    Xiongyao Xie

    2017-03-01

    Full Text Available Deformation monitoring is vital for tunnel engineering. Traditional monitoring techniques measure only a few data points, which is insufficient to understand the deformation of the entire tunnel. Terrestrial Laser Scanning (TLS is a newly developed technique that can collect thousands of data points in a few minutes, with promising applications to tunnel deformation monitoring. The raw point cloud collected from TLS cannot display tunnel deformation; therefore, a new 3D modeling algorithm was developed for this purpose. The 3D modeling algorithm includes modules for preprocessing the point cloud, extracting the tunnel axis, performing coordinate transformations, performing noise reduction and generating the 3D model. Measurement results from TLS were compared to the results of total station and numerical simulation, confirming the reliability of TLS for tunnel deformation monitoring. Finally, a case study of the Shanghai West Changjiang Road tunnel is introduced, where TLS was applied to measure shield tunnel deformation over multiple sections. Settlement, segment dislocation and cross section convergence were measured and visualized using the proposed 3D modeling algorithm.

  6. Metal particles in a ceramic matrix--scanning electron microscopy and transmission electron microscopy characterization.

    Science.gov (United States)

    Konopka, K

    2006-09-01

    This paper is concerned with ceramic matrix (Al(2)O(3)) composites with introduced metal particles (Ni, Fe). The composites were obtained via sintering of powders under very high pressure (2.5 GPa). Scanning electron microscopy and transmission electron microscopy were chosen as the tools for the identification and description of the shape, size and distribution of the metal particles. The Al(2)O(3)-Ni composite contained agglomerates of the Ni particles surrounded by ceramic grains and nanometre-size Ni particles located inside the ceramic grains and at the ceramic grain boundaries. In the Al(2)O(3)-Fe composite, the Fe particles were mostly surrounded by ceramic grains. Moreover, holes left by the Fe particles were found. The high pressure used in the fabrication of the composites changed the shape of the metal and ceramic powder grains via plastic deformation.

  7. Investigation of Nematode Diversity using Scanning Electron Microscopy and Fluorescent Microscopy

    Science.gov (United States)

    Seacor, Taylor; Howell, Carina

    2013-03-01

    Nematode worms account for the vast majority of the animals in the biosphere. They are colossally important to global public health as parasites, and to agriculture both as pests and as beneficial inhabitants of healthy soil. Amphid neurons are the anterior chemosensory neurons in nematodes, mediating critical behaviors including chemotaxis and mating. We are examining the cellular morphology and external anatomy of amphid neurons, using fluorescence microscopy and scanning electron microscopy, respectively, of a wide range of soil nematodes isolated in the wild. We use both classical systematics (e.g. diagnostic keys) and molecular markers (e.g. ribosomal RNA) to classify these wild isolates. Our ultimate aim is to build a detailed anatomical database in order to dissect genetic pathways of neuronal development and function across phylogeny and ecology. Research supported by NSF grants 092304, 0806660, 1058829 and Lock Haven University FPDC grants

  8. Scanning probe microscopy investigation of complex-oxide heterostructures

    Science.gov (United States)

    Bi, Feng

    Advances in the growth of precisely tailored complex-oxide heterostructures have led to new emergent behavior and associated discoveries. One of the most successful examples consists of an ultrathin layer of LaAlO 3 (LAO) deposited on TiO2-terminated SrTiO3 (STO), where a high mobility quasi-two dimensional electron liquid (2DEL) is formed at the interface. Such 2DEL demonstrates a variety of novel properties, including field tunable metal-insulator transition, superconductivity, strong spin-orbit coupling, magnetic and ferroelectric like behavior. Particularly, for 3-unit-cell (3 u.c.) LAO/STO heterostructures, it was demonstrated that a conductive atomic force microscope (c-AFM) tip can be used to "write" or "erase" nanoscale conducting channels at the interface, making LAO/STO a highly flexible platform to fabricate novel nanoelectronics. This thesis is focused on scanning probe microscopy studies of LAO/STO properties. We investigate the mechanism of c-AFM lithography over 3 u.c. LAO/STO in controlled ambient conditions by using a vacuum AFM, and find that the water molecules dissociated on the LAO surface play a critical role during the c-AFM lithography process. We also perform electro-mechanical response measurements over top-gated LAO/STO devices. Simultaneous piezoresponse force microscopy (PFM) and capacitance measurements reveal a correlation between LAO lattice distortion and interfacial carrier density, which suggests that PFM could not only serve as a powerful tool to map the carrier density at the interface but also provide insight into previously reported frequency dependence of capacitance enhancement of top-gated LAO/STO structures. To study magnetism at the LAO/STO interface, magnetic force microscopy (MFM) and magnetoelectric force microscopy (MeFM) are carried out to search for magnetic signatures that depend on the carrier density at the interface. Results demonstrate an electronicallycontrolled ferromagnetic phase on top-gated LAO

  9. Three-Dimensional Laser Scanning for Geometry Documentation and Construction Management of Highway Tunnels during Excavation

    Directory of Open Access Journals (Sweden)

    Vassilis Gikas

    2012-08-01

    Full Text Available Driven by progress in sensor technology, computer software and data processing capabilities, terrestrial laser scanning has recently proved a revolutionary technique for high accuracy, 3D mapping and documentation of physical scenarios and man-made structures. Particularly, this is of great importance in the underground space and tunnel construction environment as surveying engineering operations have a great impact on both technical and economic aspects of a project. This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels. It provides a detailed overview of the static laser scanning method, its principles of operation and applications for tunnel construction operations. Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction. Specific case studies are considered based on two construction sites in Greece. Particularly, the potential of the method is examined for checking the tunnel profile, producing volume computations and validating the smoothness/thickness of shotcrete layers at an excavation stage and during the completion of excavation support and primary lining. An additional example of the use of the method in the geometric documentation of the concrete lining formwork is examined and comparisons against dimensional tolerances are examined. Experimental comparisons and analyses of the laser scanning method against conventional surveying techniques are also considered.

  10. Three-dimensional laser scanning for geometry documentation and construction management of highway tunnels during excavation.

    Science.gov (United States)

    Gikas, Vassilis

    2012-01-01

    Driven by progress in sensor technology, computer software and data processing capabilities, terrestrial laser scanning has recently proved a revolutionary technique for high accuracy, 3D mapping and documentation of physical scenarios and man-made structures. Particularly, this is of great importance in the underground space and tunnel construction environment as surveying engineering operations have a great impact on both technical and economic aspects of a project. This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels. It provides a detailed overview of the static laser scanning method, its principles of operation and applications for tunnel construction operations. Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction. Specific case studies are considered based on two construction sites in Greece. Particularly, the potential of the method is examined for checking the tunnel profile, producing volume computations and validating the smoothness/thickness of shotcrete layers at an excavation stage and during the completion of excavation support and primary lining. An additional example of the use of the method in the geometric documentation of the concrete lining formwork is examined and comparisons against dimensional tolerances are examined. Experimental comparisons and analyses of the laser scanning method against conventional surveying techniques are also considered.

  11. Isometric Tunnel Placement in Ulnar Collateral Ligament Reconstruction with Single CT Scan

    Directory of Open Access Journals (Sweden)

    Erica Kholinne

    2017-01-01

    Full Text Available Background. Isometric tunnel placement for anterior bundle of the medial collateral ligament (MCL reconstruction is mandatory for successful surgery. Purpose. This study aimed to demonstrate a useful method for identifying isometric tunnel placement using a single computed tomography (CT scan. Study Design. Descriptive Laboratory Study. Methods. Five normal elbows were scanned at 4 different flexion angles at 45° increment. Three-dimensional models were analyzed using 2 different approaches: single and multiple CT scans methods. Ligament footprints in the humerus and the ulna were registered. Ligament length and isometric points were defined. The locations of the isometric points were imported into both methods to be compared. Results. There was no significant difference between 2 methods in calculating the length in every zone. There was also no significant difference in determining isometric ligament’s origin point, which is located approximately 18.2±4.0 mm and 18.4±2.9 mm for single and multiple CT, respectively, measured inferolaterally from medial epicondyle. Conclusions. A solid preoperative plan is critical when predicting tunnel locations due to the difficulty in finding isometric points and the individuality of optimal bone tunnel locations. Using single CT scan, optimal locations can be predicted with the same accuracy as a multiple CT scans with less radiation exposure.

  12. Preliminary Study of In Vivo Formed Dental Plaque Using Confocal Microscopy and Scanning Electron Microscopy

    Directory of Open Access Journals (Sweden)

    KA. Al-Salihi

    2009-12-01

    Full Text Available Objective: Confocal laser scanning microscopy (CLSM is relatively a new light microscopical imaging technique with a wide range of applications in biological sciences. The primary value of CLSM for the biologist is its ability to provide optical sections from athree-dimensional specimen. The present study was designed to assess the thickness and content of in vivo accumulated dental plaque using CLSM and scanning electron microscopy (SEM.Materials and Methods: Acroflat lower arch splints (acrylic appliance were worn by five participants for three days without any disturbance. The formed plaques were assessed using CLSM combined with vital fluorescence technique and SEM.Results: In this study accumulated dental plaque revealed varied plaque microflora vitality and thickness according to participant’s oral hygiene. The thickness of plaque smears ranged from 40.32 to 140.72 μm and 65.00 to 128.88 μm for live (vital and dead accumulated microorganisms, respectively. Meanwhile, the thickness of plaque on the appliance ranged from 101 μm to 653 μm. CLSM revealed both dead and vital bacteria on the surface of the dental plaque. In addition, SEM revealed layers of various bacterial aggregations in all dental plaques.Conclusion: This study offers a potent non-invasive tool to evaluate and assess the dental plaque biofilm, which is a very important factor in the development of dental caries.

  13. Reflection across plant cell boundaries in confocal laser scanning microscopy.

    Science.gov (United States)

    Liu, D Y T; Kuhlmey, B T; Smith, P M C; Day, D A; Faulkner, C R; Overall, R L

    2008-08-01

    The fluorescence patterns of proteins tagged with the green fluorescent protein (GFP) and its derivatives are routinely used in conjunction with confocal laser scanning microscopy to identify their sub-cellular localization in plant cells. GFP-tagged proteins localized to plasmodesmata, the intercellular junctions of plants, are often identified by single or paired punctate labelling across the cell wall. The observation of paired puncta, or 'doublets', across cell boundaries in tissues that have been transformed through biolistic bombardment is unexpected if there is no intercellular movement of the GFP-tagged protein, since bombardment usually leads to the transformation of single, isolated cells. We expressed a putative plasmodesmal protein tagged with GFP by bombarding Allium porrum epidermal cells and assessed the nature of the doublets observed at the cell boundaries. Doublets were formed when fluorescent spots were abutting a cell boundary and were only observable at certain focal planes. Fluorescence emitted from the half of a doublet lying outside the transformed cells was polarized. Optical simulations performed using finite-difference time-domain computations showed a dramatic distortion of the confocal microscope's point spread function when imaging voxels close to the plant cell wall due to refractive index differences between the wall and the cytosol. Consequently, axially and radially out-of-focus light could be detected. A model of this phenomenon suggests how a doublet may form when imaging only a single real fluorescent body in the vicinity of a plant cell wall using confocal microscopy. We suggest, therefore, that the appearance of doublets across cell boundaries is insufficient evidence for plasmodesmal localization due to the effects of the cell wall on the reflection and scattering of light.

  14. Quantitative photon tunneling and shear-force microscopy of planar waveguide splitter and mixers

    NARCIS (Netherlands)

    Balistreri, M.L.M.; Korterik, Jeroen P.; Veldhuis, G.J.; Kuipers, L.; van Hulst, N.F.

    2001-01-01

    A combined photon scanning tunneling and shear-force microscope has been developed to investigate the optical field distribution in a planar waveguide splitter and a multibranch mode mixer. The optical intensity distribution just above the surface of a planar waveguide is mapped with subwavelength

  15. Comparison between optical-resolution photoacoustic microscopy and confocal laser scanning microscopy for turbid sample imaging.

    Science.gov (United States)

    U-Thainual, Paweena; Kim, Do-Hyun

    2015-12-01

    Optical-resolution photoacoustic microscopy (ORPAM) in theory provides lateral resolution equivalent to the optical diffraction limit. Scattering media, such as biological turbid media, attenuates the optical signal and also alters the diffraction-limited spot size of the focused beam. The ORPAM signal is generated only from a small voxel in scattering media with dimensions equivalent to the laser spot size after passing through scattering layers and is detected by an acoustic transducer, which is not affected by optical scattering. Thus, both ORPAM and confocal laser scanning microscopy (CLSM) reject scattered light. A multimodal optical microscopy platform that includes ORPAM and CLSM was constructed, and the lateral resolution of both modes was measured using patterned thin metal film with and without a scattering barrier. The effect of scattering media on the lateral resolution was studied using different scattering coefficients and was compared to computational results based on Monte Carlo simulations. It was found that degradation of lateral resolution due to optical scattering was not significant for either ORPAM or CLSM. The depth discrimination capability of ORPAM and CLSM was measured using microfiber embedded in a light scattering phantom material. ORPAM images demonstrated higher contrast compared to CLSM images partly due to reduced acoustic signal scattering.

  16. 3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy

    Science.gov (United States)

    Lerner, Thomas R.; Burden, Jemima J.; Nkwe, David O.; Pelchen-Matthews, Annegret; Domart, Marie-Charlotte; Durgan, Joanne; Weston, Anne; Jones, Martin L.; Peddie, Christopher J.; Carzaniga, Raffaella; Florey, Oliver; Marsh, Mark; Gutierrez, Maximiliano G.

    2017-01-01

    ABSTRACT The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here, we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy, and 3D image processing and analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research. PMID:27445312

  17. Scanning near-field infrared microscopy on semiconductor structures

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, Rainer

    2011-01-15

    literature. While the structures of the first system were in the micrometer regime, the capability to probe buried nanostructures is demonstrated at a sample of indium arsenide quantum dots. Those dots are covered by a thick layer of gallium arsenide. For the first time ever, it is shown experimentally that transitions between electron states in single quantum dots can be investigated by near-field microscopy. By monitoring the near-field response of these quantum dots while scanning the wavelength of the incident light beam, it was possible to obtain characteristic near-field signatures of single dots. Near-field contrasts up to 30 % could be measured for resonant excitation of electrons in the conduction band of the indium arsenide dots. (orig.)

  18. Cryo-planing for cryo-scanning electron microscopy.

    Science.gov (United States)

    Nijsse, J; van Aelst, A C

    1999-01-01

    In the past decade, investigators of cryo-planing for low-temperature scanning electron microscopy (cryo-SEM) have developed techniques that enable observations of flat sample surfaces. This study reviews these sample preparation techniques, compares and contrasts their results, and introduces modifications that improve results from cryo-planing. A prerequisite for all successful cryo-planing required a stable attachment of the specimen to a holder. In most cases, clamping with a screw mechanism and using indium as space-filler sufficed. Once this problem was solved, any of three existing cryo-planing methods could be used to provide successful results: cryo-milling, microtomy in a cold room, and cryo-ultramicrotomy. This study introduces modifications to the cryo-planing technique that produces flat surfaces of any desired plane through a specimen. These flat surfaces of frozen, fully hydrated samples can be used to improve observations from cryo-SEM as well as to enhance results from x-ray microanalysis and (digital) image analysis. Cryo-planing results of chrysanthemum (Dendranthema x grandiflorum Tzvelev) stems, hazel (Corylus avelane L.) stems, and repeseed (Brassica napus L.) pistils are presented to illustrate the use of the planing method on fibrous, hard, and delicate materials, respectively.

  19. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    Energy Technology Data Exchange (ETDEWEB)

    Lunov, O., E-mail: lunov@fzu.cz; Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A. [Institute of Physics AS CR, Prague 18221 (Czech Republic); Deyneka, I. G.; Meshkovskii, I. K. [St. Petersburg State University of Information Technologies, Mechanics and Optics, St. Petersburg 197101 (Russian Federation); Syková, E. [Institute of Experimental Medicine AS CR, Prague 14220 (Czech Republic); Kubinová, Š. [Institute of Physics AS CR, Prague 18221 (Czech Republic); Institute of Experimental Medicine AS CR, Prague 14220 (Czech Republic)

    2015-02-02

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy.

  20. Band excitation method applicable to scanning probe microscopy

    Science.gov (United States)

    Jesse, Stephen [Knoxville, TN; Kalinin, Sergei V [Knoxville, TN

    2010-08-17

    Methods and apparatus are described for scanning probe microscopy. A method includes generating a band excitation (BE) signal having finite and predefined amplitude and phase spectrum in at least a first predefined frequency band; exciting a probe using the band excitation signal; obtaining data by measuring a response of the probe in at least a second predefined frequency band; and extracting at least one relevant dynamic parameter of the response of the probe in a predefined range including analyzing the obtained data. The BE signal can be synthesized prior to imaging (static band excitation), or adjusted at each pixel or spectroscopy step to accommodate changes in sample properties (adaptive band excitation). An apparatus includes a band excitation signal generator; a probe coupled to the band excitation signal generator; a detector coupled to the probe; and a relevant dynamic parameter extractor component coupled to the detector, the relevant dynamic parameter extractor including a processor that performs a mathematical transform selected from the group consisting of an integral transform and a discrete transform.

  1. Humidity effects on scanning polarization force microscopy imaging

    Science.gov (United States)

    Shen, Yue; Zhou, Yuan; Sun, Yanxia; Zhang, Lijuan; Wang, Ying; Hu, Jun; Zhang, Yi

    2017-08-01

    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.

  2. Scanning reflection ion microscopy in a helium ion microscope

    Directory of Open Access Journals (Sweden)

    Yuri V. Petrov

    2015-05-01

    Full Text Available Reflection ion microscopy (RIM is a technique that uses a low angle of incidence and scattered ions to form an image of the specimen surface. This paper reports on the development of the instrumentation and the analysis of the capabilities and limitations of the scanning RIM in a helium ion microscope (HIM. The reflected ions were detected by their “conversion” to secondary electrons on a platinum surface. An angle of incidence in the range 5–10° was used in the experimental setup. It was shown that the RIM image contrast was determined mostly by surface morphology but not by the atomic composition. A simple geometrical analysis of the reflection process was performed together with a Monte Carlo simulation of the angular dependence of the reflected ion yield. An interpretation of the RIM image formation and a quantification of the height of the surface steps were performed. The minimum detectable step height was found to be approximately 5 nm. RIM imaging of an insulator surface without the need for charge compensation was successfully demonstrated.

  3. Breast tissue characterization with high-frequency scanning acoustic microscopy

    Science.gov (United States)

    Kumon, R. E.; Bruno, I.; Heartwell, B.; Maeva, E.

    2004-05-01

    We have performed imaging of breast tissue using scanning acoustic microscopy (SAM) in the range of 25-50 MHz with the goal of accurately and rapidly determining the structure and composition throughout the volume of the samples. In contrast to traditional histological slides, SAM images can be obtained without special preparation, sometimes even without sectioning, but with sufficiently high spatial resolution to give information comparable to surface optical images. As a result, the use of high-frequency SAM at the time of breast lumpectomy to identify disease-free margins has the potential to reduce reoperative rates, patient anxiety, and local recurrence. However, only limited work has been performed to characterize breast tissue in the frequency range above clinical ultrasound devices. The samples are 4-cm2-thick sections (2-3 mm) taken from mastectomies and preserved in formalin. They are placed between two plates and immersed in water during imaging. Attenuation images are acquired by focusing the acoustic beam at the top and bottom of the samples, although better results were obtained for bottom focusing. For purposes of comparison and identification of histological features, acoustical images will be presented along with optical images obtained from the same samples. [Work supported by CIHR.

  4. An overview on bioaerosols viewed by scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wittmaack, K. [GSF-National Research Centre for Environment and Health, Institute of Radiation Protection, 85758 Neuherberg (Germany)]. E-mail: wittmaack@gsf.de; Wehnes, H. [GSF-National Research Centre for Environment and Health, Institute of Pathology, 85758 Neuherberg (Germany); Heinzmann, U. [GSF-National Research Centre for Environment and Health, Institute of Pathology, 85758 Neuherberg (Germany); Agerer, R. [Ludwig-Maximilians University Munich, Department Biology, Biodiversity Research: Mycology, Menzinger Stasse 67, 80638 Munich (Germany)

    2005-06-15

    Bioaerosols suspended in ambient air were collected with single-stage impactors at a semiurban site in southern Germany during late summer and early autumn. Sampling was mostly carried out at a nozzle velocity of 35 m/s, corresponding to a minimum aerodynamic diameter (cut-off diameter) of aerosol particles of 0.8 {mu}m. The collected particles, sampled for short periods ({approx}15 min) to avoid pile-up, were characterized by scanning electron microscopy (SEM). The observed bioaerosols include brochosomes, fungal spores, hyphae, insect scales, hairs of plants and, less commonly, bacteria and epicuticular wax. Brochosomes, which serve as a highly water repellent body coating of leafhoppers, are hollow spheroids with diameters around 400 nm, resembling C{sub 60} or footballs (soccer balls). They are usually airborne not as individuals but in the form of large clusters containing up to 10,000 individual species or even more. Various types of spores and scales were observed, but assignment turned out be difficult due to the large number of fungi and insects from which they may have originated. Pollens were observed only once. The absence these presumably elastic particles suggests that they are frequently lost, at the comparatively high velocities, due to bounce-off from the nonadhesive impaction surfaces.

  5. Simplifying Electron Beam Channeling in Scanning Transmission Electron Microscopy (STEM).

    Science.gov (United States)

    Wu, Ryan J; Mittal, Anudha; Odlyzko, Michael L; Mkhoyan, K Andre

    2017-08-01

    Sub-angstrom scanning transmission electron microscopy (STEM) allows quantitative column-by-column analysis of crystalline specimens via annular dark-field images. The intensity of electrons scattered from a particular location in an atomic column depends on the intensity of the electron probe at that location. Electron beam channeling causes oscillations in the STEM probe intensity during specimen propagation, which leads to differences in the beam intensity incident at different depths. Understanding the parameters that control this complex behavior is critical for interpreting experimental STEM results. In this work, theoretical analysis of the STEM probe intensity reveals that intensity oscillations during specimen propagation are regulated by changes in the beam's angular distribution. Three distinct regimes of channeling behavior are observed: the high-atomic-number (Z) regime, in which atomic scattering leads to significant angular redistribution of the beam; the low-Z regime, in which the probe's initial angular distribution controls intensity oscillations; and the intermediate-Z regime, in which the behavior is mixed. These contrasting regimes are shown to exist for a wide range of probe parameters. These results provide a new understanding of the occurrence and consequences of channeling phenomena and conditions under which their influence is strengthened or weakened by characteristics of the electron probe and sample.

  6. Scanning electron microscopy of eggs of Sabethes cyaneus.

    Science.gov (United States)

    Santos-Mallet, Jacenir; Sarmento, Juliana Soares; Alencar, Jeronimo; Müller, Gerson Azulim; Oliveira, Eliana Medeiros; Foster, Woodbridge A; Marcondes, Carlos Brisola

    2013-03-01

    Mosquitoes of the Neotropical genus Sabethes, some species of which are yellow fever vectors, most often develop through the immature stages in tree holes. Sabethes eggs have not been previously characterized using scanning electron microscopy. Eggs of Sabethes cyaneus (length: 349.6 +/- 2.7 microm; width: 172.6 +/- 1.14 microm; n = 10) are almost biconical when examined from the top. From a lateral perspective 2 surfaces can be seen. One surface is smooth and more convex, whereas the other is less convex and partially covered by a network from which many fungiform tubercles arise. The micropyle is situated on the smooth surface of the pointed anterior tip and is surrounded by an irregular row of tubercles, some of which are leaf shaped. No structures possibly involved in adhesion to surfaces are visible. When hatching, the egg splits dorsoventrally approximately two-thirds of the length from the anterior end. The tubercles appear to be water repellent, and the more convex/smoother surface is downturned, and this position on water was confirmed by direct observation. The eggs float free on the water surface.

  7. Scanning electron microscopy applied to seed-borne fungi examination.

    Science.gov (United States)

    Alves, Marcelo de Carvalho; Pozza, Edson Ampélio

    2009-07-01

    The aim of this study was to test the standard scanning electron microscopy (SEM) as a potential alternative to study seed-borne fungi in seeds, by two different conditions of blotter test and water restriction treatment. In the blotter test, seeds were subjected to conditions that enabled pathogen growth and expression, whereas the water restriction method consisted in preventing seed germination during the incubation period, resulting in the artificial inoculation of fungi. In the first condition, seeds of common bean (Phaseolus vulgaris L.), maize (Zea mays L.), and cotton (Gossypium hirsutum L.) were submitted to the standard blotter test and then prepared and observed with SEM. In the second condition, seeds of cotton (G. hirsutum), soybean (Glycine max L.), and common bean (P. vulgaris L.) were, respectively, inoculated with Colletotrichum gossypii var. cephalosporioides, Colletotrichum truncatum, and Colletotrichum lindemuthianum by the water restriction technique, followed by preparation and observation with SEM. The standard SEM methodology was adopted to prepare the specimens. Considering the seeds submitted to the blotter test, it was possible to identify Fusarium sp. on maize, C. gossypii var. cephalosporioides, and Fusarium oxysporum on cotton, Aspergillus flavus, Penicillium sp., Rhizopus sp., and Mucor sp. on common bean. Structures of C. gossypii var. cephalosporioides, C. truncatum, and C. lindemuthianum were observed in the surface of inoculated seeds. (c) 2009 Wiley-Liss, Inc.

  8. [Scanning electron microscopy findings in titanium middle ear prostheses].

    Science.gov (United States)

    Schwager, K

    2000-12-01

    Titanium as a biomaterial in ossicular replacement has widely spread within the last couple of years. 23 prostheses (12 PORPs, partial ossicular replacement prostheses and 11 TORPs total ossicular replacement prostheses) removed during revision surgery were studied using scanning electron microscopy. The average implantation time was 8 (range 3-15) months. The specimens were investigated regarding tissue growth, epithelialization, inflammation and cellular signs of rejection. Only few prostheses were totally covered by connective tissue or epithelium due to technical problems in removing the implant and the covering tissue as one specimen. But this offered the possibility to study the interface at the edges where the tissue was torn off. The connective tissue looked unremarkable. Polygonal squamous epithelium was detected on several implants. Respiratory epithelium with ciliated cells and mucus producing goblet cells was seen in two specimens. In cases of cholesteatoma or protrusion the explanted prostheses showed typical rosette-like formation of hornifying squamous epithelium. According to underlying disease a lymphocytic infiltration could be seen. There were no cellular signs of incompatibility noticed neither macrophages nor foreign body giant cells. From these investigations titanium seems to be a favorable biomaterial for ossicular replacement with good acceptance also in an implantation site showing chronic inflammation.

  9. Imaging of surface plasmon polariton interference using phase-sensitive scanning tunneling microscope

    NARCIS (Netherlands)

    Jose, J.; Segerink, Franciscus B.; Korterik, Jeroen P.; Herek, Jennifer Lynn; Offerhaus, Herman L.

    2011-01-01

    We report the surface plasmon polariton interference, generated via a ‘buried’ gold grating, and imaged using a phase-sensitive Photon Scanning Tunneling Microscope (PSTM). The phase-resolved PSTM measurement unravels the complex surface plasmon polariton interference fields at the gold-air

  10. Local electronic structure of Fe(001) surfaces studied by scanning tunneling spectroscopy

    NARCIS (Netherlands)

    Bischoff, M.M.J.; Yamada, T.K.; Fang, C.M.; Groot, R.A. de; Kempen, H. van

    2003-01-01

    Scanning tunneling spectroscopy is used to study the local electronic structure of Fe(001) whiskers. The influence of a voltage dependent background on the apparent peak energies in the dI/dV curves is discussed. A relation between this background and the apparent barrier height is established. The

  11. The study of electrical conductivity of DNA molecules by scanning tunneling spectroscopy

    Science.gov (United States)

    Sharipov, T. I.; Bakhtizin, R. Z.

    2017-10-01

    An interest to the processes of charge transport in DNA molecules is very high, due to perspective of their using in nanoelectronics. The original sample preparation for studying electrical conductivity of DNA molecules by scanning tunneling spectroscopy has been proposed and tested. The DNA molecules immobilized on gold surface have been imaged clearly and their current-voltage curves have been measured.

  12. Measurements with an ultrafast scanning tunnelling microscope on photoexcited semiconductor layers

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1998-01-01

    Summary form only given. We demonstrate the use of a ultrafast scanning tunnelling microscopes (USTM) for detecting laser-induced field transients on semiconductor layers. In principle, the instrument can detect transient field changes thus far observed as far-field THz radiation in the near-fiel...

  13. Quasi interference of perpendicularly polarized guided modes observed with a photon scanning tunneling microscope

    NARCIS (Netherlands)

    Balistreri, M.L.M.; Driessen, A.; Korterik, Jeroen P.; Kuipers, L.; van Hulst, N.F.

    2000-01-01

    The simultaneous detection of TE- as well as TM-polarized light with a photon scanning tunneling microscope leads to a quasi- interference pattern of these mutually perpendicular polarized fields. This interference pattern has been observed in the optical field distribution as a function of both

  14. Improved Visualization of Vertebrate Nuclear Pore Complexes by Field Emission Scanning Electron Microscopy

    National Research Council Canada - National Science Library

    Shaulov, Lihi; Harel, Amnon

    2012-01-01

    Field emission scanning electron microscopy (FESEM) can provide high-resolution three-dimensional surface imaging of many biological structures, including nuclear envelopes and nuclear pore complexes (NPCs...

  15. Automated Quantitative Rare Earth Elements Mineralogy by Scanning Electron Microscopy

    Science.gov (United States)

    Sindern, Sven; Meyer, F. Michael

    2016-09-01

    Increasing industrial demand of rare earth elements (REEs) stems from the central role they play for advanced technologies and the accelerating move away from carbon-based fuels. However, REE production is often hampered by the chemical, mineralogical as well as textural complexity of the ores with a need for better understanding of their salient properties. This is not only essential for in-depth genetic interpretations but also for a robust assessment of ore quality and economic viability. The design of energy and cost-efficient processing of REE ores depends heavily on information about REE element deportment that can be made available employing automated quantitative process mineralogy. Quantitative mineralogy assigns numeric values to compositional and textural properties of mineral matter. Scanning electron microscopy (SEM) combined with a suitable software package for acquisition of backscatter electron and X-ray signals, phase assignment and image analysis is one of the most efficient tools for quantitative mineralogy. The four different SEM-based automated quantitative mineralogy systems, i.e. FEI QEMSCAN and MLA, Tescan TIMA and Zeiss Mineralogic Mining, which are commercially available, are briefly characterized. Using examples of quantitative REE mineralogy, this chapter illustrates capabilities and limitations of automated SEM-based systems. Chemical variability of REE minerals and analytical uncertainty can reduce performance of phase assignment. This is shown for the REE phases parisite and synchysite. In another example from a monazite REE deposit, the quantitative mineralogical parameters surface roughness and mineral association derived from image analysis are applied for automated discrimination of apatite formed in a breakdown reaction of monazite and apatite formed by metamorphism prior to monazite breakdown. SEM-based automated mineralogy fulfils all requirements for characterization of complex unconventional REE ores that will become

  16. Outwitting the series resistance in scanning spreading resistance microscopy.

    Science.gov (United States)

    Schulze, A; Cao, R; Eyben, P; Hantschel, T; Vandervorst, W

    2016-02-01

    The performance of nanoelectronics devices critically depends on the distribution of active dopants inside these structures. For this reason, dopant profiling has been defined as one of the major metrology challenges by the international technology roadmap of semiconductors. Scanning spreading resistance microscopy (SSRM) has evolved as one of the most viable approaches over the last decade due to its excellent spatial resolution, sensitivity and quantification accuracy. However, in case of advanced device architectures like fins and nanowires a proper measurement of the spreading resistance is often hampered by the increasing impact of parasitic series resistances (e.g. bulk series resistance) arising from the confined nature of the aforementioned structures. In order to overcome this limitation we report in this paper the development and implementation of a novel SSRM mode (fast Fourier transform-SSRM: FFT-SSRM) which essentially decouples the spreading resistance from parasitic series resistance components. We show that this can be achieved by a force modulation (leading to a modulated spreading resistance signal) in combination with a lock-in deconvolution concept. In this paper we first introduce the principle of operation of the technique. We discuss in detail the underlying physical mechanisms as well as the technical implementation on a state-of-the-art atomic force microscope (AFM). We demonstrate the performance of FFT-SSRM and its ability to remove substantial series resistance components in practice. Eventually, the possibility of decoupling the spreading resistance from the intrinsic probe resistance will be demonstrated and discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Environmental scanning electron microscopy observation of the ultrastructure of Demodex.

    Science.gov (United States)

    Jing, Xu; Shuling, Guo; Ying, Liu

    2005-12-01

    In this study, numbers of Demodex of hair follicles and sebaceous glands were prepared and the ultrastructure (especially the mouthparts) of Demodex was observed firstly with environmental scanning electron microscopy (ESEM). The most suitable treatment methods and optimal environmental condition for observing the genus samples were found. The samples were washed with detergent and rinsed with distilled water, and then were taken to the specimen stage, on which there was carbon adhesive tape, using special tools. When the temperature was at 5 degrees C and chamber pressure at 5 mbar respectively, the surface of the samples could be fully imaged without covering water or dehydration. The sample surfaces were plump and clear without postmortem changes and charging artifacts. Detailed information about each part of Demodex was observed by ESEM, and clear three-dimensional images were recorded. The mouthparts of D. folliculorum were composed of a complex set of structures, which included a round oral opening, a sharp oral needle, and a special hypostome that looked like a longitudinal spindle in the central position. On the end segment of palpus, there were seven strong palpal claws located on each side of the mouthparts. D. folliculorum had special piercing mouthparts, while the mouthparts of D. brevis were a simpler structure. We could not observe the oral needle of D. brevis, and there were only five pairs of palpal claws on the end segment of palpus. The offensive organs of Demodex resulted in its pathogenic effects. After studying hundreds of Demodex, we identified both female and male species of D. folliculorum, but only females of D. brevis in our sample. (c) 2005 Wiley-Liss, Inc.

  18. Spectral analysis of irregular roughness artifacts measured by atomic force microscopy and laser scanning microscopy.

    Science.gov (United States)

    Chen, Yuhang; Luo, Tingting; Ma, Chengfu; Huang, Wenhao; Gao, Sitian

    2014-12-01

    Atomic force microscopy (AFM) and laser scanning microscopy (LSM) measurements on a series of specially designed roughness artifacts were performed and the results characterized by spectral analysis. As demonstrated by comparisons, both AFM and LSM can image the complex structures with high resolution and fidelity. When the surface autocorrelation length increases from 200 to 500 nm, the cumulative power spectral density spectra of the design, AFM and LSM data reach a better agreement with each other. The critical wavelength of AFM characterization is smaller than that of LSM, and the gap between the measured and designed critical wavelengths is reduced with an increase in the surface autocorrelation length. Topography measurements of surfaces with a near zero or negatively skewed height distribution were determined to be accurate. However, obvious discrepancies were found for surfaces with a positive skewness owing to more severe dilations of either the solid tip of the AFM or the laser tip of the LSM. Further surface parameter evaluation and template matching analysis verified that the main distortions in AFM measurements are tip dilations while those in LSM are generally larger and more complex.

  19. Method to characterize the vibrational response of a beetle type scanning tunneling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Behler, S.; Rose, M.K.; Ogletree, D.F.; Salmeron, M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

    1997-01-01

    We describe a method for analyzing the external vibrations and intrinsic mechanical resonances affecting scanning probe microscopes by using the microscope as an accelerometer. We show that clear correlations can be established between the frequencies of mechanical vibrational modes and the frequencies of peaks in the tunnel current noise power spectrum. When this method is applied to our {open_quotes}beetle{close_quotes} type scanning tunneling microscope (STM), we find unexpected low frequency {open_quotes}rattling resonances{close_quotes} in the 500{endash}1700 Hz range that depend on the exact lateral position of the STM, in addition to the expected mechanical resonances of the STM above 4 kHz which are in good agreement with theoretical estimates. We believe that these rattling resonances may be a general problem for scanning probe microscopes that use some type of kinetic motion for coarse positioning. {copyright} {ital 1997 American Institute of Physics.}

  20. Probing Nanoscale Electronic and Magnetic Interaction with Scanning Tunneling Spectroscopy

    DEFF Research Database (Denmark)

    Bork, Jakob

    This thesis is concerned with fundamental research into electronic and magnetic interaction on the nanoscale. From small metallic and magnetic islands and layers to single atoms. The research revolves around magnetic interaction probed through the spectroscopic capabilities of the scanning....... This is related to research in correlated electron materials such as studies of phase transitions in heavy fermion compounds and magnetic interaction in spintronic research. The capping of cobalt islands on Cu(111) with silver is investigated with STM and photoemission spectroscopy. It is shown that at low...... coverage the silver preferably nucleates on top of the bilayer high cobalt islands compared to directly on the Cu(111) substrate. Furthermore, the silver forms a combination of a reconstruction and a Moire pattern which is investigated with low-energy electron diraction and spectroscopic STM mapping at 6...

  1. Plastic-to-Elastic Transition in Aggregated Emulsion Networks, Studied with Atomic Force Microscopy-Confocal Scanning Laser Microscopy Microrheology

    NARCIS (Netherlands)

    Filip, D.; Duits, Michael H.G.; Uricanu, V.I.; Mellema, J.

    2006-01-01

    In this paper, we demonstrate how the simultaneous application of atomic force microscopy (AFM) and confocal scanning laser microscopy (CSLM) can be used to characterize the (local) rheological properties of soft condensed matter at micrometer length scales. Measurement of AFM force curves as a

  2. The Observation of Martensite and Magnetic Domain Structures in Ni53Mn24Ga23 Shape Memory Alloys by Scanning Electron Acoustic Microscopy and Scanning Thermal Microscopy

    Science.gov (United States)

    Zhao, Kun-Yu; Zeng, Hua-Rong; Song, Hong-Zhang; Hui, Sen-Xing; Li, Guo-Rong; Yin, Qing-Rui

    2012-05-01

    We present observations of martensite variants and ferromagnetic domain structures of Ni53Mn24Ga23 ferromagnetic shape memory alloys with a pure tetragonal martensitic phase by using scanning electron acoustic microscopy (SEAM) and scanning thermal microscopy (SThM). Electron acoustic images show a polycrystalline morphology with martensite variants. Direct coincidence between crystallographic martensitic twin variants and magnetic domains is found. A domain-like structure, obtained by SThM, is firstly reported, and then confirmed by magnetic force microscopy (MFM). The experimental results will be helpful for investigating the local thermal properties of ferromagnets and understanding the relationship between martensite variants and magnetic domains.

  3. Observation of the sweating in lipstick by scanning electron microscopy.

    Science.gov (United States)

    Seo, S Y; Lee, I S; Shin, H Y; Choi, K Y; Kang, S H; Ahn, H J

    1999-06-01

    The relationship between the wax matrix in lipstick and sweating has been investigated by observing the change of size and shape of the wax matrix due to sweating by Scanning Electron Microscopy (SEM). For observation by SEM, a lipstick sample was frozen in liquid nitrogen. The oil in the lipstick was then extracted in cold isopropanol (-70 degrees C) for 1-3 days. After the isopropanol was evaporated, the sample was sputtered with gold and examined by SEM. The change of wax matrix underneath the surface from fine, uniform structure to coarse, nonuniform structure resulted from the caking of surrounding wax matrix. The oil underneath the surface migrated to the surface of lipstick with sweating; consequently the wax matrix in that region was rearranged into the coarse matrix. In case of flamed lipstick, sweating was delayed and the wax matrix was much coarser than that of the unflamed one. The larger wax matrix at the surface region was good for including oil. The effect of molding temperature on sweating was also studied. As the molding temperature rose, sweating was greatly reduced and the size of the wax matrix increased. It was found that sweating was influenced by the compatibility of wax and oil. A formula consisting of wax and oil that have good compatibility has a tendency to reduce sweating and increase the size of the wax matrix. When pigments were added to wax and oil, the size of the wax matrix was changed, but in all cases sweating was increased due to the weakening of the binding force between wax and oil. On observing the thick membrane of wax at the surface of lipstick a month after molding it was also found that sweating was influenced by ageing. In conclusion, the structure of the wax matrix at the surface region of lipstick was changed with the process of flaming, molding temperature, compatibility of wax and oil, addition of pigment, and ageing. In most cases, as the size of the wax matrix was increased, sweating was reduced and delayed.

  4. Scanning tunneling spectroscopy study of the proximity effect in a disordered two-dimensional metal.

    Science.gov (United States)

    Serrier-Garcia, L; Cuevas, J C; Cren, T; Brun, C; Cherkez, V; Debontridder, F; Fokin, D; Bergeret, F S; Roditchev, D

    2013-04-12

    The proximity effect between a superconductor and a highly diffusive two-dimensional metal is revealed in a scanning tunneling spectroscopy experiment. The in situ elaborated samples consist of superconducting single crystalline Pb islands interconnected by a nonsuperconducting atomically thin disordered Pb wetting layer. In the vicinity of each superconducting island the wetting layer acquires specific tunneling characteristics which reflect the interplay between the proximity-induced superconductivity and the inherent electron correlations of this ultimate diffusive two-dimensional metal. The observed spatial evolution of the tunneling spectra is accounted for theoretically by combining the Usadel equations with the theory of dynamical Coulomb blockade; the relevant length and energy scales are extracted and found in agreement with available experimental data.

  5. A NEW APPROACH FOR SUBWAY TUNNEL DEFORMATION MONITORING: HIGH-RESOLUTION TERRESTRIAL LASER SCANNING

    Directory of Open Access Journals (Sweden)

    J. Li

    2012-07-01

    Full Text Available With the improvement of the accuracy and efficiency of laser scanning technology, high-resolution terrestrial laser scanning (TLS technology can obtain high precise points-cloud and density distribution and can be applied to high-precision deformation monitoring of subway tunnels and high-speed railway bridges and other fields. In this paper, a new approach using a points-cloud segmentation method based on vectors of neighbor points and surface fitting method based on moving least squares was proposed and applied to subway tunnel deformation monitoring in Tianjin combined with a new high-resolution terrestrial laser scanner (Riegl VZ-400. There were three main procedures. Firstly, a points-cloud consisted of several scanning was registered by linearized iterative least squares approach to improve the accuracy of registration, and several control points were acquired by total stations (TS and then adjusted. Secondly, the registered points-cloud was resampled and segmented based on vectors of neighbor points to select suitable points. Thirdly, the selected points were used to fit the subway tunnel surface with moving least squares algorithm. Then a series of parallel sections obtained from temporal series of fitting tunnel surfaces were compared to analysis the deformation. Finally, the results of the approach in z direction were compared with the fiber optical displacement sensor approach and the results in x, y directions were compared with TS respectively, and comparison results showed the accuracy errors of x, y, z directions were respectively about 1.5 mm, 2 mm, 1 mm. Therefore the new approach using high-resolution TLS can meet the demand of subway tunnel deformation monitoring.

  6. Scanning tunneling potentiometry implemented into a multi-tip setup by software.

    Science.gov (United States)

    Lüpke, F; Korte, S; Cherepanov, V; Voigtländer, B

    2015-12-01

    We present a multi-tip scanning tunneling potentiometry technique that can be implemented into existing multi-tip scanning tunneling microscopes without installation of additional hardware. The resulting setup allows flexible in situ contacting of samples under UHV conditions and subsequent measurement of the sample topography and local electric potential with resolution down to Å and μV, respectively. The performance of the potentiometry feedback is demonstrated by thermovoltage measurements on the Ag/Si(111)-(√3×√3)R30° surface by resolving a standing wave pattern. Subsequently, the ability to map the local transport field as a result of a lateral current through the sample surface is shown on Ag/Si(111)-(√3×√3)R30° and Si(111) - (7 × 7) surfaces.

  7. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    OpenAIRE

    Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

    2016-01-01

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called ?big-data? methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient ima...

  8. Visible Light Emission from Atomic Scale Patterns Fabricated by the Scanning Tunneling Microscope

    DEFF Research Database (Denmark)

    Thirstrup, C.; Sakurai, M.; Stokbro, Kurt

    1999-01-01

    Scanning tunneling microscope (STM) induced light emission from artificial atomic scale structures comprising silicon dangling bonds on hydrogen-terminated Si(001) surfaces has been mapped spatially and analyzed spectroscopically in the visible spectral range. The light emission is based on a novel...... a quasipoint source with a spatial extension similar to the size of a dangling bond. [S0031-9007(98)08376-8]....

  9. Fermi-level alignment at metal-carbon nanotube interfaces: application to scanning tunneling spectroscopy

    OpenAIRE

    Xue, Yongqiang; Datta, Supriyo

    1999-01-01

    At any metal-carbon nanotube interface there is charge transfer and the induced interfacial field determines the position of the carbon nanotube band structure relative to the metal Fermi-level. In the case of a single-wall carbon nanotube (SWNT) supported on a gold substrate, we show that the charge transfers induce a local electrostatic potential perturbation which gives rise to the observed Fermi-level shift in scanning tunneling spectroscopy (STS) measurements. We also discuss the relevan...

  10. Second-harmonic scanning optical microscopy of semiconductor quantum dots

    DEFF Research Database (Denmark)

    Vohnsen, B.; Bozhevolnyi, S.I.; Pedersen, K.

    2001-01-01

    Second-harmonic (SH) optical imaging of self-assembled InAlGaAs quantum dots (QD's) grown on a GaAs(0 0 1) substrate has been accomplished at room temperature by use of respectively a scanning far-field optical microscope in reflection mode and a scanning near-field optical microscope...... in transmission mode. In both cases the SH signal peaks at a pump wavelength of similar to 885 nm in correspondence to the maximum in the photoluminescence spectrum of the QD sample. SH near-field optical images exhibit spatial signal variations on a subwavelength scale that depend on the pump wavelength. We...

  11. Focusing and scanning microscopy with propagating surface plasmons

    NARCIS (Netherlands)

    Gjonaj, B.; Aulbach, Jochen; Johnson, P.M.; Mosk, Allard; Kuipers, L.; Lagendijk, Aart

    2013-01-01

    Here we demonstrate a novel surface plasmon polariton (SPP) microscope which is capable of imaging below the optical diffraction limit. A plasmonic lens, generated through phase-structured illumination, focuses SPPs down to their diffraction limit and scans the focus with steps as small as 10 nm.

  12. Scanning Emitter Lifetime Imaging Microscopy for Spontaneous Emission Control

    DEFF Research Database (Denmark)

    Frimmer, Martin; Chen, Yuntian; Koenderink, A. Femius

    2011-01-01

    We report an experimental technique to map and exploit the local density of optical states of arbitrary planar nanophotonic structures. The method relies on positioning a spontaneous emitter attached to a scanning probe deterministically and reversibly with respect to its photonic environment while...

  13. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    Science.gov (United States)

    Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

    2016-05-01

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

  14. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography.

    Science.gov (United States)

    Jesse, S; Chi, M; Belianinov, A; Beekman, C; Kalinin, S V; Borisevich, A Y; Lupini, A R

    2016-05-23

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called "big-data" methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

  15. [Scanning electron microscopic investigations of cutting edge quality in lamellar keratotomy using the Wavelight femtosecond laser (FS-200) : What influence do spot distance and an additional tunnel have?

    Science.gov (United States)

    Hammer, T; Höche, T; Heichel, J

    2018-01-01

    Femtosecond lasers (fs-lasers) are established cutting instruments for the creation of LASIK flaps. Previous studies often showed even rougher surfaces after application of fs-laser systems compared to lamellar keratotomy with mechanical microkeratomes. When cutting the cornea with fs-lasers, an intrastromal gas development occurs, which has a potentially negative influence on the cutting quality if the gas cannot be dissipated; therefore, manufacturers have chosen the way of gas assimilation in so-called pockets. The investigated system creates a tunnel which opens under the conjunctiva. The aim of this study was to investigate the effects of a tunnel as well as the influence of different spot distances on the quality of cut surfaces and edges. In this experimental study on freshly enucleated porcine eyes (n = 15), the following cuts were carried out with the FS-200 (Wavelight, Erlangen, Germany): 1. standard setting (spot and line separation 8 µm), 2. with tunnel for gas drainage, 3. without gas-conducting tunnel, 4. with increased spot spacing (spot and line separation 9 μm instead of 8 μm) and 5. with reduced spot spacing (spot and line separation 7 μm instead of 8 μm). Subsequently, scanning electron microscopy (FEI Quanta 650, Hillsboro, OR) of the cut edges and surfaces as well as the gas drain tunnel were performed. The evaluation was based on an established score. The current fs-laser system (200 Hz) is able to create smooth cutting surfaces and sharp edges. The changed density of laser pulses compared to the standard settings with a reduced or increased distance between the pulses, did not achieve any further improvement in the surface quality. The gas-conducting tunnel could be detected by scanning electron microscope. In the case of cutting without a tunnel, roughened surfaces and irregularities on the cutting edges were found. When the FS-200 fs-laser is used, LASIK cuts with very smooth cut surfaces and sharp cutting

  16. Simulation study of secondary electron images in scanning ion microscopy

    CERN Document Server

    Ohya, K

    2003-01-01

    The target atomic number, Z sub 2 , dependence of secondary electron yield is simulated by applying a Monte Carlo code for 17 species of metals bombarded by Ga ions and electrons in order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM). In addition to the remarkable reversal of the Z sub 2 dependence between the Ga ion and electron bombardment, a fine structure, which is correlated to the density of the conduction band electrons in the metal, is calculated for both. The brightness changes of the secondary electron images in SIM and SEM are simulated using Au and Al surfaces adjacent to each other. The results indicate that the image contrast in SIM is much more sensitive to the material species and is clearer than that for SEM. The origin of the difference between SIM and SEM comes from the difference in the lateral distribution of secondary electrons excited within the escape depth.

  17. Video rate near-field scanning optical microscopy

    Science.gov (United States)

    Bukofsky, S. J.; Grober, R. D.

    1997-11-01

    The enhanced transmission efficiency of chemically etched near-field optical fiber probes makes it possible to greatly increase the scanning speed of near-field optical microscopes. This increase in system bandwidth allows sub-diffraction limit imaging of samples at video rates. We demonstrate image acquisition at 10 frames/s, rate-limited by mechanical resonances in our scanner. It is demonstrated that the optical signal to noise ratio is large enough for megahertz single pixel acquisition rates.

  18. Probing defect states in polycrystalline GaN grown on Si(111) by sub-bandgap laser-excited scanning tunneling spectroscopy

    Science.gov (United States)

    Hsiao, F.-M.; Schnedler, M.; Portz, V.; Huang, Y.-C.; Huang, B.-C.; Shih, M.-C.; Chang, C.-W.; Tu, L.-W.; Eisele, H.; Dunin-Borkowski, R. E.; Ebert, Ph.; Chiu, Y.-P.

    2017-01-01

    We demonstrate the potential of sub-bandgap laser-excited cross-sectional scanning tunneling microscopy and spectroscopy to investigate the presence of defect states in semiconductors. The characterization method is illustrated on GaN layers grown on Si(111) substrates without intentional buffer layers. According to high-resolution transmission electron microscopy and cathodoluminescence spectroscopy, the GaN layers consist of nanoscale wurtzite and zincblende crystallites with varying crystal orientations and hence contain high defect state densities. In order to discriminate between band-to-band excitation and defect state excitations, we use sub-bandgap laser excitation. We probe a clear increase in the tunnel current at positive sample voltages during sub-bandgap laser illumination for the GaN layer with high defect density, but no effect is found for high quality GaN epitaxial layers. This demonstrates the excitation of free charge carriers at defect states. Thus, sub-bandgap laser-excited scanning tunneling spectroscopy is a powerful complimentary characterization tool for defect states.

  19. Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses.

    Science.gov (United States)

    Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David

    2014-09-01

    Limbal ring (also known as 'circle') contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or 'enclosed' within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of 'circle' contact lenses. Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1 μm below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. © 2014 The Authors. Clinical and Experimental

  20. Contribution of Metal Layer Thickness for Quantitative Backscattered Electron Imaging of Field Emission Scanning Electron Microscopy

    National Research Council Canada - National Science Library

    Kim, Hyonchol; Takei, Hiroyuki; Negishi, Tsutomu; Kudo, Masato; Terazono, Hideyuki; Yasuda, Kenji

    2012-01-01

    ...) imaging in field emission scanning electron microscopy (FE-SEM) were studied to evaluate the potential of using these particles as simultaneously distinguishable labels of target molecules in FE-SEM studies...

  1. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by Scanning Electron Microscopy

    NARCIS (Netherlands)

    Hartsuiker, Liesbeth; van Es, Peter; Petersen, Wilhelmina; van Leeuwen, Ton; Terstappen, Leonardus Wendelinus Mathias Marie; Otto, Cornelis

    2011-01-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample

  2. Combination of scanning probe microscopy techniques for evaluating the electrical parameters of individual multiwalled carbon nanotubes

    Science.gov (United States)

    Sokolov, D. V.; Davletkildeev, N. A.; Bolotov, V. V.; Lobov, I. A.

    2017-10-01

    Using two techniques of scanning probe microscopy, the electrical properties (work function, Fermi level position, free carriers’ concentration, electrical resistance, conductivity, and carriers’ mobility) of individual multiwalled carbon nanotubes were evaluated.

  3. Time-resolved scanning electron microscopy with polarization analysis

    Energy Technology Data Exchange (ETDEWEB)

    Frömter, Robert, E-mail: rfroemte@physik.uni-hamburg.de; Oepen, Hans Peter [Institut für Nanostruktur-und Festkörperphysik, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Kloodt, Fabian; Rößler, Stefan; Frauen, Axel; Staeck, Philipp; Cavicchia, Demetrio R. [Institut für Nanostruktur-und Festkörperphysik, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg (Germany); Bocklage, Lars [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Röbisch, Volker; Quandt, Eckhard [Institute for Materials Science, Christian-Albrechts-Universität zu Kiel, 24143 Kiel (Germany)

    2016-04-04

    We demonstrate the feasibility of investigating periodically driven magnetization dynamics in a scanning electron microscope with polarization analysis based on spin-polarized low-energy electron diffraction. With the present setup, analyzing the time structure of the scattering events, we obtain a temporal resolution of 700 ps, which is demonstrated by means of imaging the field-driven 100 MHz gyration of the vortex in a soft-magnetic FeCoSiB square. Owing to the efficient intrinsic timing scheme, high-quality movies, giving two components of the magnetization simultaneously, can be recorded on the time scale of hours.

  4. Scanning transmission electron microscopy: Albert Crewe's vision and beyond.

    Science.gov (United States)

    Krivanek, Ondrej L; Chisholm, Matthew F; Murfitt, Matthew F; Dellby, Niklas

    2012-12-01

    Some four decades were needed to catch up with the vision that Albert Crewe and his group had for the scanning transmission electron microscope (STEM) in the nineteen sixties and seventies: attaining 0.5Å resolution, and identifying single atoms spectroscopically. With these goals now attained, STEM developments are turning toward new directions, such as rapid atomic resolution imaging and exploring atomic bonding and electronic properties of samples at atomic resolution. The accomplishments and the future challenges are reviewed and illustrated with practical examples. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. [Scanning electron microscopy of heat-damaged bone tissue].

    Science.gov (United States)

    Harsanyl, L

    1977-02-01

    Parts of diaphyses of bones were exposed to high temperature of 200-1300 degrees C. Damage to the bone tissue caused by the heat was investigated. The scanning electron microscopic picture seems to be characteristic of the temperature applied. When the bones heated to the high temperature of 700 degrees C characteristic changes appear on the periostal surface, higher temperatura on the other hand causes damage to the compact bone tissue and can be observed on the fracture-surface. Author stresses the importance of this technique in the legal medicine and anthropology.

  6. Evaluation of the bleached human enamel by Scanning Electron Microscopy

    DEFF Research Database (Denmark)

    Miranda, Carolina Baptista; Pagani, Clovis; Benetti, Ana Raquel

    2005-01-01

    Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning...... characteristic of an erosive process that took place on human enamel. Depression areas, including the formation of craters, and exposure of enamel rods could also be detected. Conclusion: Bleaching effects on enamel morphology were randomly distributed throughout enamel surface and various degrees of enamel...

  7. Special raster scanning for reduction of charging effects in scanning electron microscopy.

    Science.gov (United States)

    Suzuki, Kazuhiko; Oho, Eisaku

    2014-01-01

    A special raster scanning (SRS) method for reduction of charging effects is developed for the field of SEM. Both a conventional fast scan (horizontal direction) and an unusual scan (vertical direction) are adopted for acquiring raw data consisting of many sub-images. These data are converted to a proper SEM image using digital image processing techniques. About sharpness of the image and reduction of charging effects, the SRS is compared with the conventional fast scan (with frame-averaging) and the conventional slow scan. Experimental results show the effectiveness of SRS images. By a successful combination of the proposed scanning method and low accelerating voltage (LV)-SEMs, it is expected that higher-quality SEM images can be more easily acquired by the considerable reduction of charging effects, while maintaining the resolution. © 2013 Wiley Periodicals, Inc.

  8. Anticipating, measuring, and minimizing MEMS mirror scan error to improve laser scanning microscopy's speed and accuracy.

    Science.gov (United States)

    Giannini, John P; York, Andrew G; Shroff, Hari

    2017-01-01

    We describe a method to speed up microelectromechanical system (MEMS) mirror scanning by > 20x, while also improving scan accuracy. We use Landweber deconvolution to determine an input voltage which would produce a desired output, based on the measured MEMS impulse response. Since the MEMS is weakly nonlinear, the observed behavior deviates from expectations, and we iteratively improve our input to minimize this deviation. This allows customizable MEMS angle vs. time with <1% deviation from the desired scan pattern. We demonstrate our technique by optimizing a point scanning microscope's raster patterns to image mammal submandibular gland and pollen at ~10 frames/s.

  9. Advantages of environmental scanning electron microscopy in studies of microorganisms.

    Science.gov (United States)

    Collins, S P; Pope, R K; Scheetz, R W; Ray, R I; Wagner, P A; Little, B J

    1993-08-01

    Microorganisms, including bacteria, fungi, protozoa, and microalgae, are composed predominantly of water which prohibits direct observation in a traditional scanning electron microscope (SEM). Preparation for SEM requires that microorganisms be fixed, frozen or dehydrated, and coated with a conductive film before observation in a high vacuum environment. Sample preparation may mechanically disturb delicate samples, compromise morphological information, and introduce other artifacts. The environmental scanning electron microscope (ESEM) provides a technology for imaging hydrated or dehydrated biological samples with minimal manipulation and without the need for conductive coatings. Sporulating cultures of three fungi, Aspergillus sp., Cunninghamella sp., and Mucor sp., were imaged in the ESEM to assess usefulness of the instrument in the direct observation of delicate, uncoated, biological specimens. Asexual sporophores showed no evidence of conidial displacement or disruption of sporangia. Uncoated algal cells of Euglena gracilis and Spirogyra sp. were examined using the backscatter electron detector (BSE) and the environmental secondary electron detector (ESD) of the ESEM. BSE images had more clearly defined intracellular structures, whereas ESD gave a clearer view of the surface E. gracilis cells fixed with potassium permanganate, Spirogyra sp. stained with Lugol's solution, and Saprolegnia sp. fixed with osmium tetroxide were compared using BSE and ESD to demonstrate that cellular details could be enhanced by the introduction of heavy metals. The effect of cellular water on signal quality was evaluated by comparing hydrated to critical point dried specimens.

  10. In-situ Scanning Transmission X-Ray Microscopy of Catalytic Solids and Related Nanomaterials

    NARCIS (Netherlands)

    de Groot, F.M.F.; de Smit, E.; van Schooneveld, M.M.; Aramburo, L.R.; Weckhuysen, B.M.

    2013-01-01

    The present status of in-situ scanning transmission X-ray microscopy (STXM) is reviewed, with an emphasis on the abilities of the STXM technique in comparison with electron microscopy. The experimental aspects and interpretation of X-ray absorption spectroscopy (XAS) are briefly introduced and the

  11. Core/shell nanofiber characterization by Raman scanning microscopy

    Science.gov (United States)

    Sfakis, Lauren; Sharikova, Anna; Tuschel, David; Costa, Felipe Xavier; Larsen, Melinda; Khmaladze, Alexander; Castracane, James

    2017-01-01

    Core/shell nanofibers are becoming increasingly popular for applications in tissue engineering. Nanofibers alone provide surface topography and increased surface area that promote cellular attachment; however, core/shell nanofibers provide the versatility of incorporating two materials with different properties into one. Such synthetic materials can provide the mechanical and degradation properties required to make a construct that mimics in vivo tissue. Many variations of these fibers can be produced. The challenge lies in the ability to characterize and quantify these nanofibers post fabrication. We developed a non-invasive method for the composition characterization and quantification at the nanoscale level of fibers using Confocal Raman microscopy. The biodegradable/biocompatible nanofibers, Poly (glycerol-sebacate)/Poly (lactic-co-glycolic) (PGS/PLGA), were characterized as a part of a fiber scaffold to quickly and efficiently analyze the quality of the substrate used for tissue engineering. PMID:28271000

  12. Customized patterned substrates for highly versatile correlative light-scanning electron microscopy

    Science.gov (United States)

    Benedetti, Lorena; Sogne, Elisa; Rodighiero, Simona; Marchesi, Davide; Milani, Paolo; Francolini, Maura

    2014-01-01

    Correlative light electron microscopy (CLEM) combines the advantages of light and electron microscopy, thus making it possible to follow dynamic events in living cells at nanometre resolution. Various CLEM approaches and devices have been developed, each of which has its own advantages and technical challenges. We here describe our customized patterned glass substrates, which improve the feasibility of correlative fluorescence/confocal and scanning electron microscopy. PMID:25391455

  13. A scanning tunneling microscope break junction method with continuous bias modulation.

    Science.gov (United States)

    Beall, Edward; Yin, Xing; Waldeck, David H; Wierzbinski, Emil

    2015-09-28

    Single molecule conductance measurements on 1,8-octanedithiol were performed using the scanning tunneling microscope break junction method with an externally controlled modulation of the bias voltage. Application of an AC voltage is shown to improve the signal to noise ratio of low current (low conductance) measurements as compared to the DC bias method. The experimental results show that the current response of the molecule(s) trapped in the junction and the solvent media to the bias modulation can be qualitatively different. A model RC circuit which accommodates both the molecule and the solvent is proposed to analyze the data and extract a conductance for the molecule.

  14. Molecular images and vibrational spectroscopy of sorbic acid with the scanning tunneling microscope

    Science.gov (United States)

    Smith, Douglas P. E.; Kirk, Michael D.; Quate, Calvin F.

    1987-06-01

    Images of sorbic acid molecules absorbed onto graphite have been taken with a scanning tunneling microscope (STM) operating in liquid helium. Molecular clusters were clearly observed, as was the atomic structure of the graphite substrate. The molecules were seen to diffuse across the substrate at a rate of about 1 Å/min. When dI/dV vs V was measured with the STM probe directly over a sorbic acid molecule, a well-defined spectrum of peaks was obtained whose energies corresponded to the vibrational resonances of the molecule. Large changes in the spectra occurred if the tip was moved a lateral distance of 5 Å.

  15. PSD microscopy: a new technique for adaptive local scanning of microscale objects.

    Science.gov (United States)

    Rahimi, Mehdi; Shen, Yantao

    2017-01-01

    A position-sensitive detector/device (PSD) is a sensor that is capable of tracking the location of a laser beam on its surface. PSDs are used in many scientific instruments and technical applications including but not limited to atomic force microscopy, human eye movement monitoring, mirrors or machine tool alignment, vibration analysis, beam position control and so on. This work intends to propose a new application using the PSD. That is a new microscopy system called scanning PSD microscopy. The working mechanism is about putting an object on the surface of the PSD and fast scanning its area with a laser beam. To achieve a high degree of accuracy and precision, a reliable framework was designed using the PSD. In this work, we first tried to improve the PSD reading and its measurement performance. This was done by minimizing the effects of noise, distortion and other disturbing parameters. After achieving a high degree of confidence, the microscopy system can be implemented based on the improved PSD measurement performance. Later to improve the scanning efficiency, we developed an adaptive local scanning system to scan the whole area of the PSD in a short matter of time. It was validated that our comprehensive and adaptive local scanning method can shorten the scanning time in order of hundreds of times in comparison with the traditional raster scanning without losing any important information about the scanned 2D objects. Methods are also introduced to scan very complicated objects with bifurcations and crossings. By incorporating all these methods, the new microscopy system is capable of scanning very complicated objects in the matter of a few seconds with a resolution that is in order of a few micrometers.

  16. Identification of sandstone core damage using scanning electron microscopy

    Science.gov (United States)

    Ismail, Abdul Razak; Jaafar, Mohd Zaidi; Sulaiman, Wan Rosli Wan; Ismail, Issham; Shiunn, Ng Yinn

    2017-12-01

    Particles and fluids invasion into the pore spaces causes serious damage to the formation, resulting reduction in petroleum production. In order to prevent permeability damage for a well effectively, the damage mechanisms should be identified. In this study, water-based drilling fluid was compared to oil-based drilling fluids based on microscopic observation. The cores were damaged by several drilling fluid systems. Scanning electron microscope (SEM) was used to observe the damage mechanism caused by the drilling fluids. Results showed that the ester based drilling fluid system caused the most serious damage followed by synthetic oil based system and KCI-polymer system. Fine solids and filtrate migration and emulsion blockage are believed to be the major mechanisms controlling the changes in flow properties for the sandstone samples.

  17. The theory and practice of high resolution scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Joy, D.C. (Tennessee Univ., Knoxville, TN (USA) Oak Ridge National Lab., TN (USA))

    1990-01-01

    Recent advances in instrumentation have produced the first commercial examples of what can justifiably be called High Resolution Scanning Electron Microscopes. The key components of such instruments are a cold field emission gun, a small-gap immersion probe-forming lens, and a clean dry-pumped vacuum. The performance of these microscopes is characterized by several major features including a spatial resolution, in secondary electron mode on solid specimens, which can exceed 1nm on a routine basis; an incident probe current density of the order of 10{sup 6} amps/cm{sup 2}; and the ability to maintain these levels of performance over an accelerating voltage range of from 1 to 30keV. This combination of high resolution, high probe current, low contamination and flexible electron-optical conditions provides many new opportunitites for the application of the SEM to materials science, physics, and the life sciences. 27 refs., 14 figs.

  18. U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rhodes, Mark A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schemer-Kohrn, Alan L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Guzman, Anthony D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-03-30

    The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

  19. U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rhodes, Mark A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schemer-Kohrn, Alan L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Guzman, Anthony D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-10-01

    The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

  20. Scanning probe microscopy and field emission schemes for studying electron emission from polycrystalline diamond

    OpenAIRE

    Chubenko, Oksana; Baturin, Stanislav S.; Baryshev, Sergey V.

    2016-01-01

    The letter introduces a diagram that rationalizes tunneling atomic force microscopy (TUNA) observations of electron emission from polycrystalline diamonds as described in recent publications. The direct observations of electron emission from grain boundary sites by TUNA could indeed be evidence of electrons originating from grain boundaries under external electric fields. At the same time, from the diagram it follows that TUNA and field emission schemes are complimentary rather than equivalen...

  1. High-resolution photon-scanning tunneling microscope measurements of the whispering gallery modes in a cylindrical microresonator

    NARCIS (Netherlands)

    Klunder, D.J.W.; Balistreri, M.L.M.; Blom, F.C.; Driessen, A.; Hoekstra, Hugo; Kuipers, L.; van Hulst, N.F.

    2000-01-01

    A detailed analysis of spatio-spectral photon scanning tunneling microscope scans of the light intensity inside a cylindrical microresonator has been carried out. By comparing the experimental results with theory, it is shown that the inclusion of spectral mode-beat phenomena is crucial for an

  2. Quantitative three-dimensional ice roughness from scanning electron microscopy

    Science.gov (United States)

    Butterfield, Nicholas; Rowe, Penny M.; Stewart, Emily; Roesel, David; Neshyba, Steven

    2017-03-01

    We present a method for inferring surface morphology of ice from scanning electron microscope images. We first develop a novel functional form for the backscattered electron intensity as a function of ice facet orientation; this form is parameterized using smooth ice facets of known orientation. Three-dimensional representations of rough surfaces are retrieved at approximately micrometer resolution using Gauss-Newton inversion within a Bayesian framework. Statistical analysis of the resulting data sets permits characterization of ice surface roughness with a much higher statistical confidence than previously possible. A survey of results in the range -39°C to -29°C shows that characteristics of the roughness (e.g., Weibull parameters) are sensitive not only to the degree of roughening but also to the symmetry of the roughening. These results suggest that roughening characteristics obtained by remote sensing and in situ measurements of atmospheric ice clouds can potentially provide more facet-specific information than has previously been appreciated.

  3. Scanning Electron Microscopy with Samples in an Electric Field

    Science.gov (United States)

    Frank, Ludĕk; Hovorka, Miloš; Mikmeková, Šárka; Mikmeková, Eliška; Müllerová, Ilona; Pokorná, Zuzana

    2012-01-01

    The high negative bias of a sample in a scanning electron microscope constitutes the “cathode lens” with a strong electric field just above the sample surface. This mode offers a convenient tool for controlling the landing energy of electrons down to units or even fractions of electronvolts with only slight readjustments of the column. Moreover, the field accelerates and collimates the signal electrons to earthed detectors above and below the sample, thereby assuring high collection efficiency and high amplification of the image signal. One important feature is the ability to acquire the complete emission of the backscattered electrons, including those emitted at high angles with respect to the surface normal. The cathode lens aberrations are proportional to the landing energy of electrons so the spot size becomes nearly constant throughout the full energy scale. At low energies and with their complete angular distribution acquired, the backscattered electron images offer enhanced information about crystalline and electronic structures thanks to contrast mechanisms that are otherwise unavailable. Examples from various areas of materials science are presented.

  4. OSTEOBLAST ADHESION OF BREAST CANCER CELLS WITH SCANNING ACOUSTIC MICROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Chiaki Miyasaka; Robyn R. Mercer; Andrea M. Mastro; Ken L. Telschow

    2005-03-01

    Breast cancer frequently metastasizes to the bone. Upon colonizing bone tissue, the cancer cells stimulate osteoclasts (cells that break bone down), resulting in large lesions in the bone. The breast cancer cells also affect osteoblasts (cells that build new bone). Conditioned medium was collected from a bone-metastatic breast cancer cell line, MDA-MB-231, and cultured with an immature osteoblast cell line, MC3T3-E1. Under these conditions the osteoblasts acquired a changed morphology and appeared to adherer in a different way to the substrate and to each other. To characterize cell adhesion, MC3T3-E1 osteoblasts were cultured with or without MDA-MB-231 conditioned medium for two days, and then assayed with a mechanical scanning acoustic reflection microscope (SAM). The SAM indicated that in normal medium the MC3T3-E1 osteoblasts were firmly attached to their plastic substrate. However, MC3T3-E1 cells cultured with MDA-MB-231 conditioned medium displayed both an abnormal shape and poor adhesion at the substrate interface. The cells were fixed and stained to visualize cytoskeletal components using optical microscopic techniques. We were not able to observe these differences until the cells were quite confluent after 7 days of culture. However, using the SAM, we were able to detect these changes within 2 days of culture with MDA-MB-231 conditioned medium

  5. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy

    Science.gov (United States)

    Levin, Barnaby D. A.; Padgett, Elliot; Chen, Chien-Chun; Scott, M. C.; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruña, Hector D.; Robinson, Richard D.; Ercius, Peter; Kourkoutis, Lena F.; Miao, Jianwei; Muller, David A.; Hovden, Robert

    2016-06-01

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180° tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of post-processing and visualization techniques. Researchers interested in creating novel data processing and reconstruction algorithms will now have access to state of the art experimental test data.

  6. Scanning electron microscopy investigations regarding Adonis vernalis L. flower morphology

    Directory of Open Access Journals (Sweden)

    Irina Neta GOSTIN

    2009-11-01

    Full Text Available The floral morphology of Adonis vernalis L. was observed with a scanning electron microscope (SEM. The investigations are important to clarify some taxonomical problems and also could provide useful diagnostic elements for the identification of this medicinal plant in powdered materials. All floral organs are initiated spirally and centripetally and develop centripetally. The petals (8-12 are shorter than the sepals (5-6 in early developmental stages. The petals are disposed on spiral (with 3-4 whorls. The stamens (numerous are unbranched and reach maturity centripetally; they are free of the perianth. The anther walls consisting of a single layer epidermis in the anther wall surrounding the sporagenous tissue, one row of endothecium, two to four rows of middle layer and one row of tapetum layer. In the anther walls, the tapetal cells, by glandular type, persist later in ontogenesis. Pollen grains are tricolpate with echinate surface. The gynoecium is multiple, apocarpous with distinct carpels. The carpels are ascidiate from the beginning. At the base of each carpel, numerousness short, unicellular, trichomes are present. The stigma differentiates as two crests along the ventral slit of the ovary. Each carpel contains a single ovule inside the ovary cavity. The mature ovule is anatropous, with two integuments. It is almost parallel to the funicle.

  7. Fabrication and characterization of probes for combined scanning electrochemical/optical microscopy experiments.

    Science.gov (United States)

    Lee, Youngmi; Bard, Allen J

    2002-08-01

    A technique that combines scanning electrochemical microscopy (SECM) and optical microscopy (OM) was implemented with a new probe tip. The tip for scanning electrochemicaVoptical microscopy (SECM/OM) was constructed by insulating a typical gold-coated near-field scanning optical microscopy tip using electrophoretic anodic paint. Once fabricated, the tip was characterized by steady-state cyclic voltammetry, as well as optical and electrochemical approach experiments. This tip generated a stable steady-state current and well-defined SECM approach curves for both conductive and insulating substrates. Durable tips whose geometry was a ring with < 1 microm as outer ring radius could be consistently fabricated. Simultaneous electrochemical and optical images of an interdigitated array electrode were obtained with a resolution on the micrometer scale, demonstrating good performance of the tip as both an optical and an electrochemical probe for imaging microstructures. The SECM feedback current measurements were successfully employed to determine tip-substrate distances for imaging.

  8. Candida albicans morphologies revealed by scanning electron microscopy analysis

    Directory of Open Access Journals (Sweden)

    M. Staniszewska

    2013-09-01

    Full Text Available Scanning electron microscope (SEM observations were used to analyze particular morphologies of Candida albicans clinical isolate (strain 82 and mutants defective in hyphae-promoting genes EFG1 (strain HLC52 and/ or CPH1 (strains HLC54 and Can16. Transcription factors Efg1 and Cph1 play role in regulating filamentation and adhesion of C. albicans' morphologies. Comparative analysis of such mutants and clinical isolate showed that Efg1 is required for human serum-induced cell growth and morphological switching. In the study, distinct differences between ultrastructural patterns of clinical strain's and null mutants' morphologies were observed (spherical vs tube-like blastoconidia, or solid and fragile constricted septa vs only the latter observed in strains with EFG1 deleted. In addition, wild type strain displayed smooth colonies of cells in comparison to mutants which exhibited wrinkled phenotype. It was observed that blastoconidia of clinical strain exhibited either polarly or randomly located budding. Contrariwise, morphotypes of mutants showed either multiple polar budding or a centrally located single bud scar (mother-daughter cell junction distinguishing tube-like yeast/ pseudohyphal growth (the length-to-width ratios larger than 1.5. In their planktonic form of growth, blastoconidia of clinical bloodstream isolate formed constitutively true hyphae under undiluted human serum inducing conditions. It was found that true hyphae are essential elements for developing structural integrity of conglomerate, as mutants displaying defects in their flocculation and conglomerate-forming abilities in serum. While filamentation is an important virulence trait in C. albicans the true hyphae are the morphologies which may be expected to play a role in bloodstream infections.

  9. 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.

  10. Cryo-Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM)-in-SEM for Bio- and Organo-Mineral Interface Characterization in the Environment.

    Science.gov (United States)

    Wille, Guillaume; Hellal, Jennifer; Ollivier, Patrick; Richard, Annie; Burel, Agnes; Jolly, Louis; Crampon, Marc; Michel, Caroline

    2017-11-16

    Understanding biofilm interactions with surrounding substratum and pollutants/particles can benefit from the application of existing microscopy tools. Using the example of biofilm interactions with zero-valent iron nanoparticles (nZVI), this study aims to apply various approaches in biofilm preparation and labeling for fluorescent or electron microscopy and energy dispersive X-ray spectrometry (EDS) microanalysis for accurate observations. According to the targeted microscopy method, biofilms were sampled as flocs or attached biofilm, submitted to labeling using 4',6-diamidino-2-phenylindol, lectins PNA and ConA coupled to fluorescent dye or gold nanoparticles, and prepared for observation (fixation, cross-section, freezing, ultramicrotomy). Fluorescent microscopy revealed that nZVI were embedded in the biofilm structure as aggregates but the resolution was insufficient to observe individual nZVI. Cryo-scanning electron microscopy (SEM) observations showed nZVI aggregates close to bacteria, but it was not possible to confirm direct interactions between nZVI and cell membranes. Scanning transmission electron microscopy in the SEM (STEM-in-SEM) showed that nZVI aggregates could enter the biofilm to a depth of 7-11 µm. Bacteria were surrounded by a ring of extracellular polymeric substances (EPS) preventing direct nZVI/membrane interactions. STEM/EDS mapping revealed a co-localization of nZVI aggregates with lectins suggesting a potential role of EPS in nZVI embedding. Thus, the combination of divergent microscopy approaches is a good approach to better understand and characterize biofilm/metal interactions.

  11. Scanning tunnelling spectroscopy and manipulation of double-decker phthalocyanine molecules on a semiconductor surface

    Science.gov (United States)

    Pan, Yi; Kanisawa, Kiyoshi; Ishikawa, Naoto; Fölsch, Stefan

    2017-09-01

    A scanning tunnelling microscope (STM) operated at 5 K was used to study dysprosium biphthalocyanine (DyPc2) molecules adsorbed on the inert III-V semiconductor surface InAs(1 1 1)A. Orbital imaging and scanning tunnelling spectroscopy measurements reveal that the molecular electronic structure remains largely unperturbed, indicating a weak molecule-surface binding. The molecule adsorbs at the In vacancy site of the (2  ×  2)-reconstructed surface and is highly sensitive to current-induced excitations leading to random rotational fluctuations. Owing to the weak surface binding, individual molecules can be precisely repositioned and arranged by the STM tip via attractive tip-molecule interaction. In this way, DyPc2 dimers of well-defined internal structure can be assembled which exist in two conformations of equivalent appearance. A binary switching between these two conformers can be induced by injecting electrons into one of the two molecules. The conformational change of the dimer proceeds via a concerted molecular rotation and minor lateral displacement. The synchronised switching observed here is attributed to steric interactions between the two molecules constituting the dimer.

  12. Resonant Scanning with Large Field of View Reduces Photobleaching and Enhances Fluorescence Yield in STED Microscopy.

    Science.gov (United States)

    Wu, Yong; Wu, Xundong; Lu, Rong; Zhang, Jin; Toro, Ligia; Stefani, Enrico

    2015-10-01

    Photobleaching is a major limitation of superresolution Stimulated Depletion Emission (STED) microscopy. Fast scanning has long been considered an effective means to reduce photobleaching in fluorescence microscopy, but a careful quantitative study of this issue is missing. In this paper, we show that the photobleaching rate in STED microscopy can be slowed down and the fluorescence yield be enhanced by scanning with high speed, enabled by using large field of view in a custom-built resonant-scanning STED microscope. The effect of scanning speed on photobleaching and fluorescence yield is more remarkable at higher levels of depletion laser irradiance, and virtually disappears in conventional confocal microscopy. With ≥6 GW∙cm(-2) depletion irradiance, we were able to extend the fluorophore survival time of Atto 647N and Abberior STAR 635P by ~80% with 8-fold wider field of view. We confirm that STED Photobleaching is primarily caused by the depletion light acting upon the excited fluorophores. Experimental data agree with a theoretical model. Our results encourage further increasing the linear scanning speed for photobleaching reduction in STED microscopy.

  13. Artifact mitigation of ptychography integrated with on-the-fly scanning probe microscopy

    Science.gov (United States)

    Huang, Xiaojing; Yan, Hanfei; Ge, Mingyuan; Öztürk, Hande; Nazaretski, Evgeny; Robinson, Ian K.; Chu, Yong S.

    2017-07-01

    We report our experiences with conducting ptychography simultaneously with the X-ray fluorescence measurement using the on-the-fly mode for efficient multi-modality imaging. We demonstrate that the periodic artifact inherent to the raster scan pattern can be mitigated using a sufficiently fine scan step size to provide an overlap ratio of >70%. This allows us to obtain transmitted phase contrast images with enhanced spatial resolution from ptychography while maintaining the fluorescence imaging with continuous-motion scans on pixelated grids. This capability will greatly improve the competence and throughput of scanning probe X-ray microscopy.

  14. Scanning electron microscopy and transmission electron microscopy study of hot-deformed gamma-TiAl-based alloy microstructure.

    Science.gov (United States)

    Chrapoński, J; Rodak, K

    2006-09-01

    The aim of this work was to assess the changes in the microstructure of hot-deformed specimens made of alloys containing 46-50 at.% Al, 2 at.% Cr and 2 at.% Nb (and alloying additions such as carbon and boron) with the aid of scanning electron microscopy and transmission electron microscopy techniques. After homogenization and heat treatment performed in order to make diverse lamellae thickness, the specimens were compressed at 1000 degrees C. Transmission electron microscopy examinations of specimens after the compression test revealed the presence of heavily deformed areas with a high density of dislocation. Deformation twins were also observed. Dynamically recrystallized grains were revealed. For alloys no. 2 and no. 3, the recovery and recrystallization processes were more extensive than for alloy no. 1.

  15. Spontaneous Polarization in Bio-organic Materials Studied by Scanning Pyroelectric Microscopy (SPEM) and Second Harmonic Generation Microscopy (SHGM)

    Science.gov (United States)

    Putzeys, T.; Wübbenhorst, M.; van der Veen, M. A.

    2015-06-01

    Bio-organic materials such as bones, teeth, and tendon generally show nonlinear optical (Masters and So in Handbook of Biomedical Nonlinear Optical Microscopy, 2008), pyro- and piezoelectric (Fukada and Yasuda in J Phys Soc Jpn 12:1158, 1957) properties, implying a permanent polarization, the presence of which can be rationalized by describing the growth of the sample and the creation of a polar axis according to Markov's theory of stochastic processes (Hulliger in Biophys J 84:3501, 2003; Batagiannis et al. in Curr Opin Solid State Mater Sci 17:107, 2010). Two proven, versatile techniques for probing spontaneous polarization distributions in solids are scanning pyroelectric microscopy (SPEM) and second harmonic generation microscopy (SHGM). The combination of pyroelectric scanning with SHG-microscopy in a single experimental setup leading to complementary pyroelectric and nonlinear optical data is demonstrated, providing us with a more complete image of the polarization in organic materials. Crystals consisting of a known polar and hyperpolarizable material, CNS (4-chloro-4-nitrostilbene) are used as a reference sample, to verify the functionality of the setup, with both SPEM and SHGM images revealing the same polarization domain information. In contrast, feline and human nails exhibit a pyroelectric response, but a second harmonic response is absent for both keratin containing materials, implying that there may be symmetry-allowed SHG, but with very inefficient second harmonophores. This new approach to polarity detection provides additional information on the polar and hyperpolar nature in a variety of (bio) materials.

  16. Observation of silicon carbide Schottky barrier diode under applied reverse bias using atomic force microscopy/Kelvin probe force microscopy/scanning capacitance force microscopy

    Science.gov (United States)

    Uruma, Takeshi; Satoh, Nobuo; Yamamoto, Hidekazu

    2017-08-01

    We have observed a commercial silicon-carbide Schottky barrier diode (SiC-SBD) using our novel analysis system, in which atomic force microscopy (AFM) is combined with both Kelvin probe force microscopy (KFM; for surface-potential measurement) and scanning capacitance force microscopy (SCFM; for differential-capacitance measurement). The results obtained for the SiC-SBD under an applied reverse bias indicate both the scan area in the sample and a peak value of the SCFM signal in the region where the existence of trapped electrons is deduced from the KFM analysis. Thus, our measurement system can be used to examine commercial power devices; however, novel polishing procedures are required in order to investigate the Schottky contact region.

  17. Scanning ion conductance microscopy for visualizing the three-dimensional surface topography of cells and tissues.

    Science.gov (United States)

    Nakajima, Masato; Mizutani, Yusuke; Iwata, Futoshi; Ushiki, Tatsuo

    2018-01-01

    Scanning ion conductance microscopy (SICM), which belongs to the family of scanning probe microscopy, regulates the tip-sample distance by monitoring the ion current through the use of an electrolyte-filled nanopipette as the probing tip. Thus, SICM enables "contact-free" imaging of cell surface topography in liquid conditions. In this paper, we applied hopping mode SICM for obtaining topographical images of convoluted tissue samples such as trachea and kidney in phosphate buffered saline. Some of the SICM images were compared with the images obtained by scanning electron microscopy (SEM) after drying the same samples. We showed that the imaging quality of hopping mode SICM was excellent enough for investigating the three-dimensional surface structure of the soft tissue samples. Thus, SICM is expected to be used for imaging a wide variety of cells and tissues - either fixed or alive- at high resolution under physiologically relevant liquid conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Emulation and design of terahertz reflection-mode confocal scanning microscopy based on virtual pinhole

    Science.gov (United States)

    Yang, Yong-fa; Li, Qi

    2014-12-01

    In the practical application of terahertz reflection-mode confocal scanning microscopy, the size of detector pinhole is an important factor that determines the performance of spatial resolution characteristic of the microscopic system. However, the use of physical pinhole brings some inconvenience to the experiment and the adjustment error has a great influence on the experiment result. Through reasonably selecting the parameter of matrix detector virtual pinhole (VPH), it can efficiently approximate the physical pinhole. By using this approach, the difficulty of experimental calibration is reduced significantly. In this article, an imaging scheme of terahertz reflection-mode confocal scanning microscopy that is based on the matrix detector VPH is put forward. The influence of detector pinhole size on the axial resolution of confocal scanning microscopy is emulated and analyzed. Then, the parameter of VPH is emulated when the best axial imaging performance is reached.

  19. Transmission electron microscopy study investigating Li intercalation in tunnel structured ζ-V2O5 nanowire

    Science.gov (United States)

    Mukherjee, Arijita; Yoo, Hyun Deog; Nolis, Gene; Andrews, Justin; Banerjee, Sarbajit; Cabana, Jordi; Klie, Robert; Joint Center for Energy Storage Research Collaboration

    Energy storage research has become quite relevant in recent years with the advent of smarter electronic devices and electric vehicles that demand more efficient options. Orthorhombic α-V2O5 has been known as a versatile intercalation cathode host for lithium and beyond Li cations, such as Na and Mg. Recent reports have established that a novel tunnel structured polymorph, ζ-V2O5 can perform better as a cathode material, and can intercalate Li and Mg chemically. This contribution will focus on an in depth study of phase formation upon electrochemical Li intercalation of this new polymorph, ζ-V2O5 using aberration corrected scanning transmission electron microscopy(STEM) electron energy loss spectroscopy(EELS) and energy dispersive X ray spectroscopy(EDX). Results will also be presented investigating Mg and Na intercalation into this ζ-V2O5 polymorph and compare the electrochemical performance in the various scenarios directly with structural changes at an atomic scale. This work is supported by Joint Center for Energy Storage Research(JCESR).

  20. Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy

    OpenAIRE

    Hermannsd?rfer, Justus; de Jonge, Niels

    2017-01-01

    Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid c...

  1. Development of a Millikelvin dual-tip Josephson scanning tunneling microscope

    Science.gov (United States)

    Roychowdhury, Anita

    In this thesis, I first describe the design and construction of a dual-tip millikelvin STM system. The STM is mounted on a dilution refrigerator and the setup includes vibration isolation, rf-filtered wiring, an ultra high vacuum (UHV) sample preparation chamber and sample transfer mechanism. Next I describe a novel superconducting tip fabrication technique. My technique involves dry-etching sections of 250 mum diameter Nb wire with an SF6 plasma in a reactive ion etcher. I present data taken with these tips on various samples at temperatures ranging from 30 mK to 9 K. My results demonstrate that the tips are superconducting, achieve good spectroscopic energy resolution, are mechanically robust over long time periods, and are atomically sharp. I also show data characterizing the performance of our system. This data is in the form of atomic resolution images, spectroscopy, noise spectra and simultaneous scans taken with both tips of the STM. I used these to examine the tip-sample stability, cross talk between the two tips, and to extract the effective noise temperature (˜185 mK) of the sample by fitting the spectroscopy data to a voltage noise model. Finally, I present spectroscopy data taken with a Nb tip on a Nb(100) sample at 30 mK. The enhanced spectroscopic resolution at this temperature allowed me to resolve peaks in the fluctuation-dominated supercurrent at sub-gap voltages. My analysis indicates that these peaks are due to the incoherent tunneling of Cooper pairs at resonant frequencies of the STM's electromagnetic environment. By measuring the response of the STM junction to microwaves, I identified the charge carriers in this regime as Cooper pairs with charge 2e. The amplitude of the response current scales as the square of the Bessel functions, indicating that the pair tunneling originates from photon assisted tunneling in the incoherent regime, rather than the more conventionally observed Shapiro steps in the coherent regime.

  2. Data analysis using the Internet: the World Wide Web scanning probe microscopy data analysis system.

    Science.gov (United States)

    Williams, P M; Davies, M C; Roberts, C J; Tendler, S J

    1997-10-01

    The first interactive world-wide web-based image analysis system is presented (http://pharm6.pharm.nottingham.ac.uk/processing/main. html). The system, currently tailored to scanning probe microscopy image data, has been developed to permit the use of software algorithms developed within our laboratory by researchers throughout the world. The implementation and functionality of the scanning probe microscopy server is described. Feedback from users of the facility has demonstrated its value within the research community, and highlighted key operational issues which are to be addressed. A future role of Internet-based data processing software is also discussed.

  3. Stochastic Micro-Pattern for Automated Correlative Fluorescence - Scanning Electron Microscopy

    Science.gov (United States)

    Begemann, Isabell; Viplav, Abhiyan; Rasch, Christiane; Galic, Milos

    2015-01-01

    Studies of cellular surface features gain from correlative approaches, where live cell information acquired by fluorescence light microscopy is complemented by ultrastructural information from scanning electron micrographs. Current approaches to spatially align fluorescence images with scanning electron micrographs are technically challenging and often cost or time-intensive. Relying exclusively on open-source software and equipment available in a standard lab, we have developed a method for rapid, software-assisted alignment of fluorescence images with the corresponding scanning electron micrographs via a stochastic gold micro-pattern. Here, we provide detailed instructions for micro-pattern production and image processing, troubleshooting for critical intermediate steps, and examples of membrane ultra-structures aligned with the fluorescence signal of proteins enriched at such sites. Together, the presented method for correlative fluorescence – scanning electron microscopy is versatile, robust and easily integrated into existing workflows, permitting image alignment with accuracy comparable to existing approaches with negligible investment of time or capital. PMID:26647824

  4. Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses

    OpenAIRE

    Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David

    2014-01-01

    Background Limbal ring (also known as ‘circle’) contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or ‘enclosed’ within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of ‘circle’ contact lenses. Methods Scanning electron ...

  5. Superresolution upgrade for confocal spinning disk systems using image scanning microscopy (Conference Presentation)

    Science.gov (United States)

    Isbaner, Sebastian; Hähnel, Dirk; Gregor, Ingo; Enderlein, Jörg

    2017-02-01

    Confocal Spinning Disk Systems are widely used for 3D cell imaging because they offer the advantage of optical sectioning at high framerates and are easy to use. However, as in confocal microscopy, the imaging resolution is diffraction limited, which can be theoretically improved by a factor of 2 using the principle of Image Scanning Microscopy (ISM) [1]. ISM with a Confocal Spinning Disk setup (CSDISM) has been shown to improve contrast as well as lateral resolution (FWHM) from 201 +/- 20 nm to 130 +/- 10 nm at 488 nm excitation. A minimum total acquisition time of one second per ISM image makes this method highly suitable for 3D live cell imaging [2]. Here, we present a multicolor implementation of CSDISM for the popular Micro-Manager Open Source Microscopy platform. Since changes in the optical path are not necessary, this will allow any researcher to easily upgrade their standard Confocal Spinning Disk system at remarkable low cost ( 5000 USD) with an ISM superresolution option. [1]. Müller, C.B. and Enderlein, J. Image Scanning Microscopy. Physical Review Letters 104, (2010). [2]. Schulz, O. et al. Resolution doubling in fluorescence microscopy with confocal spinning-disk image scanning microscopy. Proceedings of the National Academy of Sciences of the United States of America 110, 21000-5 (2013).

  6. Artifact characterization and reduction in scanning X-ray Zernike phase contrast microscopy.

    Science.gov (United States)

    Vartiainen, Ismo; Holzner, Christian; Mohacsi, Istvan; Karvinen, Petri; Diaz, Ana; Pigino, Gaia; David, Christian

    2015-05-18

    Zernike phase contrast microscopy is a well-established method for imaging specimens with low absorption contrast. It has been successfully implemented in full-field microscopy using visible light and X-rays. In microscopy Cowley's reciprocity principle connects scanning and full-field imaging. Even though the reciprocity in Zernike phase contrast has been discussed by several authors over the past thirty years, only recently it was experimentally verified using scanning X-ray microscopy. In this paper, we investigate the image and contrast formation in scanning Zernike phase contrast microscopy with a particular and detailed focus on the origin of imaging artifacts that are typically associated with Zernike phase contrast. We demonstrate experimentally with X-rays the effect of the phase mask design on the contrast and halo artifacts and present an optimized design of the phase mask with respect to photon efficiency and artifact reduction. Similarly, due to the principle of reciprocity the observations and conclusions of this work have direct applicability to Zernike phase contrast in full-field microscopy as well.

  7. Simultaneous Bright-Field and Dark-Field Scanning Transmission Electron Microscopy in Scanning Electron Microscopy: A New Approach for Analyzing Polymer System Morphology

    Science.gov (United States)

    Patel, Binay S.

    Scanning transmission electron microscopy in scanning electron microscopy (STEM-IN-SEM) is a convenient technique for polymer characterization. Utilizing the lower accelerating voltages, larger field of view and, exclusion of post-specimen projection lens in an SEM; STEM-IN-SEM has shown results comparable to transmission electron microscopy (TEM) observation of polymer morphology. Various specimen-holder geometries and detector arrangements have been used for bright field (BF) STEM-IN-SEM imaging. To further the characterization potential of STEM-IN-SEM a new specimen holder has been developed to facilitate simultaneous BF and dark field (DF) STEM-IN-SEM imaging. A new specimen holder and a new microscope configuration were designed for this new imaging technique. BF and DF signals were maximized for optimal STEM-IN-SEM imaging. BF signal intensities were found to be twice as large as DF signal intensities. BF and DF STEM-IN-SEM imaging spatial resolutions are limited to 1.8 nm and approximately 5 nm, respectively. Simultaneous BF & DF STEM-IN-SEM imaging is applicable to both industrial and academic research environments. Examples of commodity and engineering polymer morphology characterization are provided. Results are comparable to TEM observation and may serve as a suitable precursor to STEM characterization of polymer systems. Finally, future developments of various accessories for this technique are discussed.

  8. In situ scanning tunneling microscope tip treatment device for spin polarization imaging

    Science.gov (United States)

    Li, An-Ping [Oak Ridge, TN; Jianxing, Ma [Oak Ridge, TN; Shen, Jian [Knoxville, TN

    2008-04-22

    A tip treatment device for use in an ultrahigh vacuum in situ scanning tunneling microscope (STM). The device provides spin polarization functionality to new or existing variable temperature STM systems. The tip treatment device readily converts a conventional STM to a spin-polarized tip, and thereby converts a standard STM system into a spin-polarized STM system. The tip treatment device also has functions of tip cleaning and tip flashing a STM tip to high temperature (>2000.degree. C.) in an extremely localized fashion. Tip coating functions can also be carried out, providing the tip sharp end with monolayers of coating materials including magnetic films. The device is also fully compatible with ultrahigh vacuum sample transfer setups.

  9. Local transport measurements at mesoscopic length scales using scanning tunneling potentiometry.

    Science.gov (United States)

    Wang, Weigang; Munakata, Ko; Rozler, Michael; Beasley, Malcolm R

    2013-06-07

    Under mesoscopic conditions, the transport potential on a thin film carrying a current is theoretically expected to bear spatial variation due to quantum interference. Scanning tunneling potentiometry is the ideal tool to investigate such variation, by virtue of its high spatial resolution. We report in this Letter the first detailed measurement of transport potential under mesoscopic conditions. Epitaxial graphene at a temperature of 17 K was chosen as the initial system for study because the characteristic transport length scales in this material are relatively large. Tip jumping artifacts are a major possible contribution to systematic errors; and we mitigate such problems by using custom-made slender and sharp tips manufactured by focused ion beam. In our data, we observe residual resistivity dipoles associated with topographical defects, and local peaks and dips in the potential that are not associated with topographical defects.

  10. Ex situ elaborated proximity mesoscopic structures for ultrahigh vacuum scanning tunneling spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stolyarov, V. S. [UMR 7588, Institut des Nanosciences de Paris, UPMC Univ Paris 06, Sorbonne Universités, F-75005 Paris (France); CNRS, UMR 7588, Institut des Nanosciences de Paris, F-75005 Paris (France); Institute of Solid State Physics RAS, 142432 Chernogolovka (Russian Federation); Moscow Institute of Physics and Technology, 141700 Dolgoprudny (Russian Federation); Kazan Federal University, 420008 Kazan (Russian Federation); Moscow State University, 119991 Moscow (Russian Federation); Cren, T., E-mail: tristan.cren@upmc.fr; Debontridder, F.; Brun, C. [UMR 7588, Institut des Nanosciences de Paris, UPMC Univ Paris 06, Sorbonne Universités, F-75005 Paris (France); CNRS, UMR 7588, Institut des Nanosciences de Paris, F-75005 Paris (France); Veshchunov, I. S. [Université de Bordeaux, LP2N, 351 cours de la Libération, F-33405 Talence (France); Institute of Solid State Physics RAS, 142432 Chernogolovka (Russian Federation); Skryabina, O. V. [Institute of Solid State Physics RAS, 142432 Chernogolovka (Russian Federation); Rusanov, A. Yu. [LLC “Applied radiophysics” 142432 Chernogolovka (Russian Federation); Roditchev, D. [UMR 7588, Institut des Nanosciences de Paris, UPMC Univ Paris 06, Sorbonne Universités, F-75005 Paris (France); CNRS, UMR 7588, Institut des Nanosciences de Paris, F-75005 Paris (France); LPEM-UMR 8213, CNRS, ESPCI-ParisTech, UPMC, 10 rue Vauquelin, F-75005 Paris (France)

    2014-04-28

    We apply ultrahigh vacuum Scanning Tunneling Spectroscopy (STS) at ultra-low temperature to study proximity phenomena in metallic Cu in contact with superconducting Nb. In order to solve the problem of Cu-surface contamination, Cu(50 nm)/Nb(100 nm) structures are grown by respecting the inverted order of layers on SiO{sub 2}/Si substrate. Once transferred into vacuum, the samples are cleaved at the structure-substrate interface. As a result, a contamination-free Cu-surface is exposed in vacuum. It enables high-resolution STS of superconducting correlations induced by proximity from the underlying superconducting Nb layer. By applying magnetic field, we generate unusual proximity-induced superconducting vortices and map them with a high spatial and energy resolution. The suggested method opens a way to access local electronic properties of complex electronic mesoscopic devices by performing ex situ STS under ultrahigh vacuum.

  11. Confocal laser scanning microscopy. Using new technology to answer old questions in forensic investigations.

    Science.gov (United States)

    Turillazzi, Emanuela; Karch, Steven B; Neri, Margherita; Pomara, Cristoforo; Riezzo, Irene; Fineschi, Vittorio

    2008-03-01

    Confocal laser scanning microscopy (CLSM) is a relatively new technique for microscopic imaging. It has found a wide field of application in the general sphere of biological sciences. It has completely changed the study of cells and tissues by allowing greater resolution, optical sectioning of the sample and three-dimensional sanoke reconstruction. Confocal microscopy represents a valid, precious and useful tool capable of providing data (images) of unrivalled clearness and definition. This review discusses the possible applications of confocal microscopy in specific fields of forensic investigation, with specific regard to ballistics, forensic histopathology and toxicological pathology.

  12. Ultrafast axial scanning for two-photon microscopy via a digital micromirror device and binary holography.

    Science.gov (United States)

    Cheng, Jiyi; Gu, Chenglin; Zhang, Dapeng; Wang, Dien; Chen, Shih-Chi

    2016-04-01

    In this Letter, we present an ultrafast nonmechanical axial scanning method for two-photon excitation (TPE) microscopy based on binary holography using a digital micromirror device (DMD), achieving a scanning rate of 4.2 kHz, scanning range of ∼180  μm, and scanning resolution (minimum step size) of ∼270  nm. Axial scanning is achieved by projecting the femtosecond laser to a DMD programmed with binary holograms of spherical wavefronts of increasing/decreasing radii. To guide the scanner design, we have derived the parametric relationships between the DMD parameters (i.e., aperture and pixel size), and the axial scanning characteristics, including (1) maximum optical power, (2) minimum step size, and (3) scan range. To verify the results, the DMD scanner is integrated with a custom-built TPE microscope that operates at 60 frames per second. In the experiment, we scanned a pollen sample via both the DMD scanner and a precision z-stage. The results show the DMD scanner generates images of equal quality throughout the scanning range. The overall efficiency of the TPE system was measured to be ∼3%. With the high scanning rate, the DMD scanner may find important applications in random-access imaging or high-speed volumetric imaging that enables visualization of highly dynamic biological processes in 3D with submillisecond temporal resolution.

  13. Telocytes and putative stem cells in the lungs: electron microscopy, electron tomography and laser scanning microscopy.

    Science.gov (United States)

    Popescu, Laurentiu M; Gherghiceanu, Mihaela; Suciu, Laura C; Manole, Catalin G; Hinescu, Mihail E

    2011-09-01

    This study describes a novel type of interstitial (stromal) cell - telocytes (TCs) - in the human and mouse respiratory tree (terminal and respiratory bronchioles, as well as alveolar ducts). TCs have recently been described in pleura, epicardium, myocardium, endocardium, intestine, uterus, pancreas, mammary gland, etc. (see www.telocytes.com ). TCs are cells with specific prolongations called telopodes (Tp), frequently two to three per cell. Tp are very long prolongations (tens up to hundreds of μm) built of alternating thin segments known as podomers (≤ 200 nm, below the resolving power of light microscope) and dilated segments called podoms, which accommodate mitochondria, rough endoplasmic reticulum and caveolae. Tp ramify dichotomously, making a 3-dimensional network with complex homo- and heterocellular junctions. Confocal microscopy reveals that TCs are c-kit- and CD34-positive. Tp release shed vesicles or exosomes, sending macromolecular signals to neighboring cells and eventually modifying their transcriptional activity. At bronchoalveolar junctions, TCs have been observed in close association with putative stem cells (SCs) in the subepithelial stroma. SCs are recognized by their ultrastructure and Sca-1 positivity. Tp surround SCs, forming complex TC-SC niches (TC-SCNs). Electron tomography allows the identification of bridging nanostructures, which connect Tp with SCs. In conclusion, this study shows the presence of TCs in lungs and identifies a TC-SC tandem in subepithelial niches of the bronchiolar tree. In TC-SCNs, the synergy of TCs and SCs may be based on nanocontacts and shed vesicles.

  14. Alternative configuration scheme for signal amplification with scanning ion conductance microscopy

    Science.gov (United States)

    Kim, Joonhui; Kim, Seong-Oh; Cho, Nam-Joon

    2015-02-01

    Scanning Ion Conductance Microscopy (SICM) is an emerging nanotechnology tool to investigate the morphology and charge transport properties of nanomaterials, including soft matter. SICM uses an electrolyte filled nanopipette as a scanning probe and detects current changes based on the distance between the nanopipette apex and the target sample in an electrolyte solution. In conventional SICM, the pipette sensor is excited by applying voltage as it raster scans near the surface. There have been attempts to improve upon raster scanning because it can induce collisions between the pipette sidewalls and target sample, especially for soft, dynamic materials (e.g., biological cells). Recently, Novak et al. demonstrated that hopping probe ion conductance microscopy (HPICM) with an adaptive scan method can improve the image quality obtained by SICM for such materials. However, HPICM is inherently slower than conventional raster scanning. In order to optimize both image quality and scanning speed, we report the development of an alternative configuration scheme for SICM signal amplification that is based on applying current to the nanopipette. This scheme overcomes traditional challenges associated with low bandwidth requirements of conventional SICM. Using our alternative scheme, we demonstrate successful imaging of L929 fibroblast cells and discuss the capabilities of this instrument configuration for future applications.

  15. Alternative configuration scheme for signal amplification with scanning ion conductance microscopy.

    Science.gov (United States)

    Kim, Joonhui; Kim, Seong-Oh; Cho, Nam-Joon

    2015-02-01

    Scanning Ion Conductance Microscopy (SICM) is an emerging nanotechnology tool to investigate the morphology and charge transport properties of nanomaterials, including soft matter. SICM uses an electrolyte filled nanopipette as a scanning probe and detects current changes based on the distance between the nanopipette apex and the target sample in an electrolyte solution. In conventional SICM, the pipette sensor is excited by applying voltage as it raster scans near the surface. There have been attempts to improve upon raster scanning because it can induce collisions between the pipette sidewalls and target sample, especially for soft, dynamic materials (e.g., biological cells). Recently, Novak et al. demonstrated that hopping probe ion conductance microscopy (HPICM) with an adaptive scan method can improve the image quality obtained by SICM for such materials. However, HPICM is inherently slower than conventional raster scanning. In order to optimize both image quality and scanning speed, we report the development of an alternative configuration scheme for SICM signal amplification that is based on applying current to the nanopipette. This scheme overcomes traditional challenges associated with low bandwidth requirements of conventional SICM. Using our alternative scheme, we demonstrate successful imaging of L929 fibroblast cells and discuss the capabilities of this instrument configuration for future applications.

  16. EVALUATION OF COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY APPLIED TO AN AMBIENT URBAN AEROSOL SAMPLE

    Science.gov (United States)

    Recent interest in monitoring and speciation of particulate matter has led to increased application of scanning electron microscopy (SEM) coupled with energy-dispersive x-ray analysis (EDX) to individual particle analysis. SEM/EDX provides information on the size, shape, co...

  17. Scanning electron microscopy and X-ray spectroscopy applied to mycelial phase of sporothrix schenckii

    Directory of Open Access Journals (Sweden)

    M. Thibaut

    1975-04-01

    Full Text Available Scanning electron microscopy applied to the mycelial phase of Sporothrix schenckii shows a matted mycelium with conidia of a regular pattern. X-Ray microanalysis applied in energy dispersive spectroscopy and also in wavelength dispersive spectroscopy reveals the presence of several elements of Mendeleef's classification.

  18. Bright-field scanning confocal electron microscopy using a double aberration-corrected transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng; Behan, Gavin; Kirkland, Angus I. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Nellist, Peter D., E-mail: peter.nellist@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Cosgriff, Eireann C.; D' Alfonso, Adrian J.; Morgan, Andrew J.; Allen, Leslie J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Hashimoto, Ayako [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); Takeguchi, Masaki [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); High Voltage Electron Microscopy Station, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Mitsuishi, Kazutaka [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); Quantum Dot Research Center, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Shimojo, Masayuki [High Voltage Electron Microscopy Station, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Advanced Science Research Laboratory, Saitama Institute of Technology, 1690 Fusaiji, Fukaya 369-0293 (Japan)

    2011-06-15

    Scanning confocal electron microscopy (SCEM) offers a mechanism for three-dimensional imaging of materials, which makes use of the reduced depth of field in an aberration-corrected transmission electron microscope. The simplest configuration of SCEM is the bright-field mode. In this paper we present experimental data and simulations showing the form of bright-field SCEM images. We show that the depth dependence of the three-dimensional image can be explained in terms of two-dimensional images formed in the detector plane. For a crystalline sample, this so-called probe image is shown to be similar to a conventional diffraction pattern. Experimental results and simulations show how the diffracted probes in this image are elongated in thicker crystals and the use of this elongation to estimate sample thickness is explored. -- Research Highlights: {yields} The confocal probe image in a scanning confocal electron microscopy image reveals information about the thickness and height of the crystalline layer. {yields} The form of the contrast in a three-dimensional bright-field scanning confocal electron microscopy image can be explained in terms of the confocal probe image. {yields} Despite the complicated form of the contrast in bright-field scanning confocal electron microscopy, we see that depth information is transferred on a 10 nm scale.

  19. Field-emission scanning electron microscopy of the internal cellular organization of fungi

    NARCIS (Netherlands)

    Muller, W.H.; Aelst, van A.C.; Humbel, B.M.; Krift, van der T.P.; Boekhout, T.

    2000-01-01

    Internal viewing of the cellular organization of hyphae by scanning electron microscopy is an alternative to observing sectioned fungal material with a transmission electron microscope. To study cytoplasmic organelles in the hyphal cells of fungi by SEM, colonies were chemically fixed with

  20. Morphologic differences observed by scanning electron microscopy according to the reason for pseudophakic IOL explantation

    DEFF Research Database (Denmark)

    Fernandez-Buenaga, Roberto; Alio, Jorge L.; Ramirez, Jose M.

    2015-01-01

    Purpose To compare variations in surface morphology, as studied by scanning electron microscopy (SEM), of explanted intraocular lenses (IOLs) concerning the cause leading to the explantation surgery. Methods In this prospective multicenter study, explanted IOLs were analyzed by SEM and energy-dis...

  1. DTAF: an efficient probe to study cyanobacterial-plant interaction using confocal laser scanning microscopy (CLSM)

    NARCIS (Netherlands)

    Ahmed, M.; Stal, L.J.; Hasnain, S.

    2011-01-01

    A variety of microscopic techniques have been utilized to study cyanobacterial associations with plant roots, but confocal laser scanning microscopy (CLSM) is the least used due to the unavailability of a suitable fluorescent dye. Commonly used lectins have problems with their binding ability with

  2. DTAF: an efficient probe to study cyanobacterial-plant interaction using confocal laser scanning microscopy (CLSM).

    NARCIS (Netherlands)

    Ahmed, M.; Stal, L.J.; Hasnain, S.

    2011-01-01

    A variety of microscopic techniques have been utilized to study cyanobacterial associations with plant roots, but confocal laser scanning microscopy (CLSM) is the least used due to the unavailability of a suitable fluorescent dye. Commonly used lectins have problems with their binding ability with

  3. Scanning electron microscopy with polarization analysis for multilayered chiral spin textures

    NARCIS (Netherlands)

    Lucassen, Juriaan; Kloodt-Twesten, Fabian; Frömter, Robert; Oepen, Hans Peter; Duine, Rembert A.|info:eu-repo/dai/nl/304830127; Swagten, Henk J. M.; Koopmans, Bert; Lavrijsen, Reinoud

    We show that scanning electron microscopy with polarization analysis (SEMPA) that is sensitive to both in-plane magnetization components can be used to image the out-of-plane magnetized multi-domain state in multilayered chiral spin textures. By depositing a thin layer of Fe on top of the multilayer

  4. Batch fabrication of scanning microscopy probes for thermal and magnetic imaging using standard micromachining

    NARCIS (Netherlands)

    Sarajlic, Edin; Vermeer, Rolf; Delalande, M.Y.; Siekman, Martin Herman; Huijink, R.; Fujita, H.; Abelmann, Leon

    2010-01-01

    We present a process for batch fabrication of a novel scanning microscopy probe for thermal and magnetic imaging using standard micromachining and conventional optical contact lithography. The probe features an AFM-type cantilever with a sharp pyramidal tip composed of four freestanding silicon

  5. Investigation of whispering gallery modes in microlasers by scanning near-field optical microscopy

    Science.gov (United States)

    Polubavkina, Yu S.; Kryzhanovskaya, N. V.; Nadtochiy, A. M.; Mintairov, A. M.; Lipovsky, A. A.; Scherbak, S. A.; Kulagina, M. M.; Maximov, M. V.; Zhukov, A. E.

    2017-11-01

    Near-field scanning optical microscopy (NSOM) with a spatial resolution below the light diffraction limit was used to study intensity distributions of the whispering gallery modes (WGMs) in quantum dot-based microdisk and microring lasers on GaAs with different outer diameters. Room temperature microphotoluminescence study (μPL) reveal lasing in microlasers of both geometries.

  6. RGB color coded images in scanning electron microscopy of biological surfaces

    Czech Academy of Sciences Publication Activity Database

    Kofroňová, Olga; Benada, Oldřich

    2017-01-01

    Roč. 61, č. 3 (2017), s. 349-352 ISSN 0001-723X R&D Projects: GA MŠk(CZ) LO1509; GA ČR(CZ) GA16-20229S Institutional support: RVO:61388971 Keywords : Biological surfaces * Color images * Scanning electron microscopy Subject RIV: EE - Microbiology, Virology Impact factor: 0.673, year: 2016

  7. Imaging inclusion complex formation in starch granules using confocal laser scanning microscopy

    NARCIS (Netherlands)

    Manca, Marianna; Woortman, Albert J. J.; Loos, Katja; Loi, Maria A.

    The tendency of amylose to form inclusion complexes with guest molecules has been an object of wide interest due to its fundamental role in food processing. Here we investigated the features of starch granules from several botanical sources using confocal laser scanning microscopy (CLSM) and

  8. Scanning Electron Microscopy (SEM) Procedure for HE Powders on a LEO 438VP System

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, Fowzia [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Energetic Materials Center

    2016-03-08

    This method describes the characterization of HE powders by Scanning Electron Microscopy (SEM). HE particles are dispersed onto an aluminum standard SEM specimen mount. Electron micrographs are collected at various magnifications (150 to 10,000 X) depending on HE particle size.

  9. Scanning Electron Microscopy (SEM) Procedure for HE Powders on a LEO 438VP System

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, Fowzia [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Energetic Materials Center

    2016-03-21

    This method describes the characterization of HE powders by Scanning Electron Microscopy (SEM). HE particles are dispersed onto an aluminum standard SEM specimen mount. Electron micrographs are collected at various magnifications (150 to 10,000 X) depending on HE particle size.

  10. Elastic Changes of Capsule in a Rat Knee Contracture Model Assessed by Scanning Acoustic Microscopy

    Science.gov (United States)

    Hagiwara, Y.; Chimoto, E.; Ando, A.; Saijo, Y.; Itoi, E.

    Sound speed of a capsule in a rat knee contracture model was measured by scanning acoustic microscopy. There was no statistical significant difference in the anterior capsule compared with the control group. However, the sound speed of the posterior capsule was significantly greater compared with the control group after prolonged immobilization.

  11. Pollen grain surface in Vaccinium myrtillus as seen in scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Józef Kocoń

    2014-01-01

    Full Text Available Pollen grain surface of Vaccinium myrtillus L. was analyzed by scanning electron microscopy. Pollen grains remain in tetrahedral tetrads. Grain surface is verrucose, consisting of thick, irregularly shaped muri, surrounding small, round or oval lumina. The surface of the muri is fissured, and minute papillae can also be noted.

  12. Carbon induced metal dusting of iron-nickel-chromium alloy surfaces : a scanning auger microscopy study

    NARCIS (Netherlands)

    Palasantzas, G; DeHosson, JTM

    2004-01-01

    In this work, we present an investigation on metal dusting of iron-nickel-chromium (Fe-Ni-Cr) alloy surfaces using scanning auger microscopy. It is shown that the formation of surface Cr-oxide and the surface finish condition can strongly influence and interrupt this catastrophic phenomenon. The

  13. Second-Harmonic Generation Scanning Microscopy on Domains in Al Surfaces

    DEFF Research Database (Denmark)

    Pedersen, Kjeld; Bozhevolnyi, Sergey I.

    1999-01-01

    Scanning optical second-harmonic generation microscopy has been used to investigate domains in the surface of polycrystaline Al. Strong contrast among the crystalline grains is obtained due to variations in their crystallographic orientations and thus also nonlinear response. The origin of the co...

  14. THALLUS SURFACES IN COCCOCARPIACEAE AND PANNARIACEAE (LICHENIZED ASCOMYCETES) VIEWED WITH SCANNING ELECTRON-MICROSCOPY

    NARCIS (Netherlands)

    LUMBSCH, HT; KOTHE, HW

    1992-01-01

    The thallus surfaces of species belonging to the Coccocarpiaceae and Pannariaceae were studied using scanning electron microscopy (SEM). A pored epicortex was shown in Coccocarpia ssp., Degelia gayana and D. plumbea. In the other species studied no definite pores were found. The probable systematic

  15. Cold-induced imbibition damage of lettuce embryos: A study using cryo-scanning electron microscopy

    NARCIS (Netherlands)

    Nijsse, J.; Walther, P.; Hoekstra, F.

    2004-01-01

    The impact of rehydration on a multicellular organism was studied in lettuce (Lactuca sativa L.) embryos, using cryo-scanning electron microscopy (cryo-SEM). Naked embryos were sensitive to imbibitional stress, whereas embryos with an intact, thick-walled endosperm were not. Imbibitional injury to

  16. Combining optical tweezers and scanning probe microscopy to study DNA-protein interactions

    NARCIS (Netherlands)

    Huisstede, Jurgen H G; Subramaniam, Vinod; Bennink, Martin L

    We present the first results obtained with a new instrument designed and built to study DNA-protein interactions at the single molecule level. This microscope combines optical tweezers with scanning probe microscopy and allows us to locate DNA-binding proteins on a single suspended DNA molecule. A

  17. Near-Field Scanning Optical Microscopy of Single Fluorescent Dendritic Molecules

    NARCIS (Netherlands)

    Veerman, J.A.; Levi, S.; van Veggel, F.C.J.M.; Reinhoudt, David; van Hulst, N.F.

    1999-01-01

    Individual dendritic molecules adsorbed o­n glass containing a single fluorescent rhodamine B core have been observed with near-field scanning optical microscopy (NSOM); height and fluorescence images were obtained simultaneously. The dendritic assemblies can be discriminated from free fluorescent

  18. PROBING STRESS EFFECTS IN SINGLE CRYSTAL ORGANIC TRANSISTORS BY SCANNING KELVIN PROBE MICROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Teague, L

    2010-06-11

    We report scanning Kelvin probe microscopy (SKPM) of single crystal difluoro bis(triethylsilylethynyl) anthradithiophene (diF-TESADT) organic transistors. SKPM provides a direct measurement of the intrinsic charge transport in the crystals independent of contact effects and reveals that degradation of device performance occurs over a time period of minutes as the diF-TESADT crystal becomes charged.

  19. Demonstration of synchronised scanning Lidar measurements of 2D velocity fields in a boundary-layer wind tunnel

    DEFF Research Database (Denmark)

    van Dooren, M F; Kühn, M.; Petrovic, V.

    2016-01-01

    compared to hot wire probe measurements commonly used in wind tunnels. This yielded goodness of fit coefficients of 0.969 and 0.902 for the 1 Hz averaged u- and v-components of the wind speed, respectively, validating the 2D measurement capability of the Lidar scanners. Subsequently, the measurement......This paper combines the currently relevant research methodologies of scaled wind turbine model experiments in wind tunnels with remote-sensing short-range WindScanner Lidar measurement technology. The wind tunnel of the Politecnico di Milano was equipped with three wind turbine models and two short......-range WindScanner Lidars to demonstrate the benefits of synchronised scanning Lidars in such experimental surroundings for the first time. The dualLidar system can provide fully synchronised trajectory scans with sampling time scales ranging from seconds to minutes. First, staring mode measurements were...

  20. High-contrast en bloc staining of neuronal tissue for field emission scanning electron microscopy.

    Science.gov (United States)

    Tapia, Juan Carlos; Kasthuri, Narayanan; Hayworth, Kenneth J; Schalek, Richard; Lichtman, Jeff W; Smith, Stephen J; Buchanan, JoAnn

    2012-01-12

    Conventional heavy metal poststaining methods on thin sections lend contrast but often cause contamination. To avoid this problem, we tested several en bloc staining techniques to contrast tissue in serial sections mounted on solid substrates for examination by field emission scanning electron microscopy (FESEM). Because FESEM section imaging requires that specimens have higher contrast and greater electrical conductivity than transmission electron microscopy (TEM) samples, our technique uses osmium impregnation (OTO) to make the samples conductive while heavily staining membranes for segmentation studies. Combining this step with other classic heavy metal en bloc stains, including uranyl acetate (UA), lead aspartate, copper sulfate and lead citrate, produced clean, highly contrasted TEM and scanning electron microscopy (SEM) samples of insect, fish and mammalian nervous systems. This protocol takes 7-15 d to prepare resin-embedded tissue, cut sections and produce serial section images.

  1. A compilation of cold cases using scanning electron microscopy at the University of Rhode Island

    Science.gov (United States)

    Platek, Michael J.; Gregory, Otto J.

    2015-10-01

    Scanning electron microscopy combined with microchemical analysis has evolved into one of the most widely used instruments in forensic science today. In particular, the environmental scanning electron microscope (SEM) in conjunction with energy dispersive spectroscopy (EDS), has created unique opportunities in forensic science in regard to the examination of trace evidence; i.e. the examination of evidence without altering the evidence with conductive coatings, thereby enabling criminalists to solve cases that were previously considered unsolvable. Two cold cases were solved at URI using a JEOL 5900 LV SEM in conjunction with EDS. A cold case murder and a cold missing person case will be presented from the viewpoint of the microscopist and will include sample preparation, as well as image and chemical analysis of the trace evidence using electron microscopy and optical microscopy.

  2. Growth of Pd-Filled Carbon Nanotubes on the Tip of Scanning Probe Microscopy

    Directory of Open Access Journals (Sweden)

    Tomokazu Sakamoto

    2009-01-01

    Full Text Available We have synthesized Pd-filled carbon nanotubes (CNTs oriented perpendicular to Si substrates using a microwave plasma-enhanced chemical vapor deposition (MPECVD for the application of scanning probe microscopy (SPM tip. Prior to the CVD growth, Al thin film (10 nm was coated on the substrate as a buffer layer followed by depositing a 5∼40 nm-thick Pd film as a catalyst. The diameter and areal density of CNTs grown depend largely on the initial Pd thickness. Scanning electron microscopy (SEM and transmission electron microscopy (TEM images clearly show that Pd is successfully encapsulated into the CNTs, probably leading to higher conductivity. Using optimum growth conditions, Pd-filled CNTs are successfully grown on the apex of the conventional SPM cantilever.

  3. An endolithic microbial community in dolomite rock in central Switzerland: characterization by reflection spectroscopy, pigment analyses, scanning electron microscopy, and laser scanning microscopy.

    Science.gov (United States)

    Horath, T; Neu, T R; Bachofen, R

    2006-04-01

    A community of endolithic microorganisms dominated by phototrophs was found as a distinct band a few millimeters below the surface of bare exposed dolomite rocks in the Piora Valley in the Alps. Using in situ reflectance spectroscopy, we detected chlorophyll a (Chl a), phycobilins, carotenoids, and an unknown type of bacteriochlorophyll-like pigment absorbing in vivo at about 720 nm. In cross sections, the data indicated a defined distribution of different groups of organisms perpendicular to the rock surface. High-performance liquid chromatography analyses of pigments extracted with organic solvents confirmed the presence of two types of bacteriochlorophylls besides chlorophylls and various carotenoids. Spherical organisms of varying sizes and small filaments were observed in situ with scanning electron microscopy and confocal laser scanning microscopy (one- and two-photon technique). The latter allowed visualization of the distribution of phototrophic microorganisms by the autofluorescence of their pigments within the rock. Coccoid cyanobacteria of various sizes predominated over filamentous ones. Application of fluorescence-labeled lectins demonstrated that most cyanobacteria were embedded in an exopolymeric matrix. Nucleic acid stains revealed a wide distribution of small heterotrophs. Some biological structures emitting a green autofluorescence remain to be identified.

  4. Plasma-deposited fluorocarbon films: insulation material for microelectrodes and combined atomic force microscopy-scanning electrochemical microscopy probes.

    Science.gov (United States)

    Wiedemair, Justyna; Balu, Balamurali; Moon, Jong-Seok; Hess, Dennis W; Mizaikoff, Boris; Kranz, Christine

    2008-07-01

    Pinhole-free insulation of micro- and nanoelectrodes is the key to successful microelectrochemical experiments performed in vivo or in combination with scanning probe experiments. A novel insulation technique based on fluorocarbon insulation layers deposited from pentafluoroethane (PFE, CF3CHF2) plasmas is presented as a promising electrical insulation approach for microelectrodes and combined atomic force microscopy-scanning electrochemical microscopy (AFM-SECM) probes. The deposition allows reproducible and uniform coating, which is essential for many analytical applications of micro- and nanoelectrodes such as, e.g., in vivo experiments and SECM experiments. Disk-shaped microelectrodes and frame-shaped AFM tip-integrated electrodes have been fabricated by postinsulation focused ion beam (FIB) milling. The thin insulation layer for combined AFM-SECM probes renders this fabrication technique particularly useful for submicro insulation providing radius ratios of the outer insulation versus the disk electrode (RG values) suitable for SECM experiments. Characterization of PFE-insulated AFM-SECM probes will be presented along with combined AFM-SECM approach curves and imaging.

  5. Lateral spatial resolution of thermal lens microscopy during continuous scanning for nonstaining biofilm imaging

    Science.gov (United States)

    Rossteuscher, T. T. J.; Hibara, A.; Mawatari, K.; Kitamori, T.

    2009-05-01

    The possible application of continuous scanning thermal lens microscopy (TLM) as alternative online biofilm observation method is studied. As biofilm is a heterogeneous sample, the influence of spatially limited thermal flow at the sample heterogeneities and the biofilm-environment border has to be considered. The influence of the edges on the lateral resolution with respect to scanning velocity during continuous scanning TLM was therefore evaluated. Lateral scanning experiments on 100 nm thin gold stripes showed that the maximum scan speed can be predicted from a time constant of a lock-in amplifier and the beamwidth. Since three-dimensional mapping is needed to fully characterize the biofilm structure, depth scanning experiments with stained 4 μm thick polystyrene samples with the coaxial TLM setup were evaluated for signal width at full width at half maximum. Thus, a minimum step width for depth scanning of 10 μm for observation has been acquired. A three-dimensional image of unstained biofilm grown in a flow chamber was acquired using continuous scanning TLM.

  6. Characterization of tip size and geometry of the pipettes used in scanning ion conductance microscopy.

    Science.gov (United States)

    Tognoni, Elisabetta; Baschieri, Paolo; Ascoli, Cesare; Pellegrini, Monica; Pellegrino, Mario

    2016-04-01

    Scanning ion-conductance microscopy (SICM) belongs to the family of scanning-probe microscopies. The spatial resolution of these techniques is limited by the size of the probe. In SICM the probe is a pipette, obtained by heating and pulling a glass capillary tubing. The size of the pipette tip is therefore an important parameter in SICM experiments. However, the characterization of the tip is not a consolidated routine in SICM experimental practice. In addition, potential and limitations of the different methods available for this characterization may not be known to all users. We present an overview of different methods for characterizing size and geometry of the pipette tip, with the aim of collecting and facilitating the use of several pieces of information appeared in the literature in a wide interval of time under different disciplines. In fact, several methods that have been developed for pipettes used in cell physiology can be also fruitfully employed in the characterization of the SICM probes. The overview includes imaging techniques, such as scanning electron microscopy and atomic Force microscopy, and indirect methods, which measure some physical parameter related to the size of the pipette. Examples of these parameters are the electrical resistance of the pipette filled with a saline solution and the surface tension at the pipette tip. We discuss advantages and drawbacks of the methods, which may be helpful in answering a wide range of experimental questions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Tunnel transport through CoFe{sub 2}O{sub 4} barriers investigated by conducting atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, M; Rigato, F; Fontcuberta, J [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain); Bouzehouane, K, E-mail: mfoerster@icmab.e [Unite Mixte de Physique CNRS/Thales, Route Departementale 128, 91767 Orsay (France)

    2010-07-28

    Conducting atomic force microscopy has been used to monitor the quality of spin-filtering CoFe{sub 2}O{sub 4} tunnel barriers by mapping current as a function of their thickness. We show that appropriate film annealing leads to a substantial improvement of their tunnelling properties. The contact force between tip and sample was identified to have a determining influence on the width of the distribution P(I) in current maps, thus precluding its reliable use to infer barrier characteristics. Therefore, assessment of tunnel transport should be done by means of the typical current which is a well-defined parameter at a given contact force, rather than by the current distribution width.

  8. The use of scanning ion conductance microscopy to image A6 cells.

    Science.gov (United States)

    Gorelik, Julia; Zhang, Yanjun; Shevchuk, Andrew I; Frolenkov, Gregory I; Sánchez, Daniel; Lab, Max J; Vodyanoy, Igor; Edwards, Christopher R W; Klenerman, David; Korchev, Yuri E

    2004-03-31

    Continuous high spatial resolution observations of living A6 cells would greatly aid the elucidation of the relationship between structure and function and facilitate the study of major physiological processes such as the mechanism of action of aldosterone. Unfortunately, observing the micro-structural and functional changes in the membrane of living cells is still a formidable challenge for a microscopist. Scanning ion conductance microscopy (SICM), which uses a glass nanopipette as a sensitive probe, has been shown to be suitable for imaging non-conducting surfaces bathed in electrolytes. A specialized version of this microscopy has been developed by our group and has been applied to image live cells at high-resolution for the first time. This method can also be used in conjunction with patch clamping to study both anatomy and function and identify ion channels in single cells. This new microscopy provides high-resolution images of living renal cells which are comparable with those obtained by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Continuous 24h observations under normal physiological conditions showed how A6 kidney epithelial cells changed their height, volume, and reshaped their borders. The changes in cell area correlated with the density of microvilli on the surface. Surface microvilli density ranged from 0.5 microm(-2) for extended cells to 2.5 microm(2) for shrunk cells. Patch clamping of individual cells enabled anatomy and function to be correlated. Scanning ion conductance microscopy provides unique information about living cells that helps to understand cellular function. It has the potential to become a powerful tool for research on living renal cells.

  9. Image scanning fluorescence emission difference microscopy based on a detector array.

    Science.gov (United States)

    Li, Y; Liu, S; Liu, D; Sun, S; Kuang, C; Ding, Z; Liu, X

    2017-06-01

    We propose a novel imaging method that enables the enhancement of three-dimensional resolution of confocal microscopy significantly and achieve experimentally a new fluorescence emission difference method for the first time, based on the parallel detection with a detector array. Following the principles of photon reassignment in image scanning microscopy, images captured by the detector array were arranged. And by selecting appropriate reassign patterns, the imaging result with enhanced resolution can be achieved with the method of fluorescence emission difference. Two specific methods are proposed in this paper, showing that the difference between an image scanning microscopy image and a confocal image will achieve an improvement of transverse resolution by approximately 43% compared with that in confocal microscopy, and the axial resolution can also be enhanced by at least 22% experimentally and 35% theoretically. Moreover, the methods presented in this paper can improve the lateral resolution by around 10% than fluorescence emission difference and 15% than Airyscan. The mechanism of our methods is verified by numerical simulations and experimental results, and it has significant potential in biomedical applications. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  10. Imaging metazoan nuclear pore complexes by field emission scanning electron microscopy.

    Science.gov (United States)

    Fichtman, Boris; Shaulov, Lihi; Harel, Amnon

    2014-01-01

    High resolution three-dimensional surface images of nuclear pore complexes (NPCs) can be obtained by field emission scanning electron microscopy. We present a short retrospective view starting from the early roots of microscopy, through the discovery of the cell nucleus and the development of some modern techniques for sample preparation and imaging. Detailed protocols are presented for assembling anchored nuclei in a Xenopus cell-free reconstitution system and for the exposure of the nuclear surface in mammalian cell nuclei. Immunogold labeling of metazoan NPCs and a promising new technique for delicate coating with iridium are also discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Line scan--structured illumination microscopy super-resolution imaging in thick fluorescent samples.

    Science.gov (United States)

    Mandula, Ondrej; Kielhorn, Martin; Wicker, Kai; Krampert, Gerhard; Kleppe, Ingo; Heintzmann, Rainer

    2012-10-22

    Structured illumination microscopy in thick fluorescent samples is a challenging task. The out-of-focus fluorescence background deteriorates the illumination pattern and the reconstructed images suffer from influence of noise. We present a combination of structured illumination microscopy with line scanning. This technique reduces the out-of-focus fluorescence background, which improves the modulation and the quality of the illumination pattern and therefore facilitates the reconstruction. We present super-resolution, optically sectioned images of a thick fluorescent sample, revealing details of the specimen's inner structure.

  12. Optical microscope illumination analysis using through-focus scanning optical microscopy.

    Science.gov (United States)

    Attota, Ravi Kiran; Park, Haesung

    2017-06-15

    Misalignment of the aperture diaphragm present in optical microscopes results in angular illumination asymmetry (ANILAS) at the sample plane. Here we show that through-focus propagation of ANILAS results in a lateral image shift with a focus position. This could lead to substantial errors in quantitative results for optical methods that use through-focus images such as three-dimensional nanoparticle tracking, confocal microscopy, and through-focus scanning optical microscopy (TSOM). A correlation exists between ANILAS and the slant in TSOM images. Hence, the slant in the TSOM image can be used to detect, analyze, and rectify the presence of ANILAS.

  13. Application of scanning force and near field microscopies to the characterization of minimally adhesive polymer surfaces.

    Science.gov (United States)

    Akhremitchev, Boris B; Bemis, Jason E; al-Maawali, Sabah; Sun, Yujie; Stebounova, Larissa; Walker, Gilbert C

    2003-04-01

    This mini-review reports efforts to develop new scanning probe microscopies to characterize the function and aging of textured, minimally adhesive polymer surfaces used for antifouling applications in the marine environment. Novel atomic force and infrared near field microscopy techniques have been used to characterize the polymer surface adhesion and structural properties. These techniques may find promise for characterizing the deposition of the extracellular matrix of organisms as well as aging of the polymer coating itself. The reported work is part of a larger effort to reduce biofouling on ships' hulls through the development and use of improved coating materials.

  14. In Situ Scanning Probe Microscopy and New Perspectives in Analytical Chemistry

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Zhang, Jingdong; Chi, Qijin

    1999-01-01

    for molecular- and mesoscopic-scale analytical chemistry, are then reviewed. They are illustrated by metallic electro-crystallisation and -dissolution, and in situ STM spectroscopy of large redox molecules. The biophysically oriented analytical options of in situ atomic force microscopy, and analytical chemical......The resolution of scanning probe microscopies is unpresedented but the techniques are fraught with limitations as analytical tools. These limitations and their relationship to the physical mechanisms of image contrast are first discussed. Some new options based on in situ STM, which hold prospects...

  15. Controlling molecular condensation/diffusion of copper phthalocyanine by local electric field induced with scanning tunneling microscope tip

    Science.gov (United States)

    Nagaoka, Katsumi; Yaginuma, Shin; Nakayama, Tomonobu

    2018-02-01

    We have discovered the condensation/diffusion phenomena of copper phthalocyanine (CuPc) molecules controlled with a pulsed electric field induced by the scanning tunneling microscope tip. This behavior is not explained by the conventional induced dipole model. In order to understand the mechanism, we have measured the electronic structure of the molecule by tunneling spectroscopy and also performed theoretical calculations on molecular orbitals. These data clearly indicate that the molecule is positively charged owing to charge transfer to the substrate, and that hydrogen bonding exists between CuPc molecules, which makes the molecular island stable.

  16. Development of an add-on kit for scanning confocal microscopy (Conference Presentation)

    Science.gov (United States)

    Guo, Kaikai; Zheng, Guoan

    2017-03-01

    Scanning confocal microscopy is a standard choice for many fluorescence imaging applications in basic biomedical research. It is able to produce optically sectioned images and provide acquisition versatility to address many samples and application demands. However, scanning a focused point across the specimen limits the speed of image acquisition. As a result, scanning confocal microscope only works well with stationary samples. Researchers have performed parallel confocal scanning using digital-micromirror-device (DMD), which was used to project a scanning multi-point pattern across the sample. The DMD based parallel confocal systems increase the imaging speed while maintaining the optical sectioning ability. In this paper, we report the development of an add-on kit for high-speed and low-cost confocal microscopy. By adapting this add-on kit to an existing regular microscope, one can convert it into a confocal microscope without significant hardware modifications. Compared with current DMD-based implementations, the reported approach is able to recover multiple layers along the z axis simultaneously. It may find applications in wafer inspection and 3D metrology of semiconductor circuit. The dissemination of the proposed add-on kit under $1000 budget could also lead to new types of experimental designs for biological research labs, e.g., cytology analysis in cell culture experiments, genetic studies on multicellular organisms, pharmaceutical drug profiling, RNA interference studies, investigation of microbial communities in environmental systems, and etc.

  17. Observation of mesenteric microcirculatory disturbance in rat by laser oblique scanning optical microscopy

    Science.gov (United States)

    Ding, Yichen; Zhang, Yu; Peng, Tong; Lu, Yiqing; Jin, Dayong; Ren, Qiushi; Liu, Yuying; Han, Jingyan; Xi, Peng

    2013-05-01

    Ischemia-reperfusion (I/R) injury model has been widely applied to the study of microcirculation disturbance. In this work, we used laser oblique scanning optical microscopy (LOSOM) to observe the microcirculation system in the mesentery of rat model. Utilizing a localized point-scanning detection scheme, high-contrast images of leukocytes were obtained. The extended detection capability facilitated both the automatic in vivo cell counting and the accurate measurement of the rolling velocity of leukocytes. Statistical analysis of the different treatment groups suggested that the distinction between I/R and sham groups with time lapse is significant.

  18. Practical aspects of single-pass scan Kelvin probe force microscopy

    Science.gov (United States)

    Li, Guangyong; Mao, Bin; Lan, Fei; Liu, Liming

    2012-11-01

    The single-pass scan Kelvin probe force microscopy (KPFM) in ambient condition has a few advantages over the dual-pass lift-up scan KPFM. For example, its spatial resolution is expected to be higher; and its topographical errors caused by electrostatic forces are minimized because electrostatic forces are actively suppressed during the simultaneous topographical and KPFM measurement. Because single-pass scan KPFM in ambient condition is relatively new, it received little attention in the literature so far. In this article, we discuss several major practical aspects of single-pass scan KPFM especially in ambient condition. First, we define the resolution using a point spread function. With this definition, we analyze the relation between the resolution and the scanning parameters such as tip apex radius and tip-surface distance. We further study the accuracy of KPFM based on the point spread function. Then, we analyze the sensitivity of KPFM under different operation modes. Finally, we investigate the crosstalk between the topographical image and the surface potential image and demonstrate the practical ways to minimize the crosstalk. These discussions not only help us to understand the single-pass scan KPFM but also provide practical guidance in using single-pass scan KPFM.

  19. Electron beam confinement and image contrast enhancement in near field emission scanning electron microscopy.

    Science.gov (United States)

    Kirk, T L; De Pietro, L G; Pescia, D; Ramsperger, U

    2009-04-01

    In conventional scanning electron microscopy (SEM), the lateral resolution is limited by the electron beam diameter impinging on the specimen surface. Near field emission scanning electron microscopy (NFESEM) provides a simple means of overcoming this limit; however, the most suitable field emitter remains to be determined. NFESEM has been used in this work to investigate the W (110) surface with single-crystal tungsten tips of (310), (111), and (100)-orientations. The topographic images generated from both the electron intensity variations and the field emission current indicate higher resolution capabilities with decreasing tip work function than with polycrystalline tungsten tips. The confinement of the electron beam transcends the resolution limitations of the geometrical models, which are determined by the minimum beam width.

  20. Field emission scanning electron microscopy of biofilm-growing bacteria involved in nosocomial infections.

    Science.gov (United States)

    Vuotto, Claudia; Donelli, Gianfranco

    2014-01-01

    Scanning electron microscopy (SEM) provides useful information on the shape, size, and localization within the biofilm of single bacteria as well as on the steps of biofilm formation process, on bacterial interactions, and on production of extracellular polymeric substances.When biofilms are constituted by microbial species involved in health care-associated infections, information provided by SEM can be fruitfully used not only for basic researches but also for diagnostic purposes.The protocols currently used in our laboratory for biofilm investigation by SEM are reported here. Particularly, the procedures to fix, dehydrate, and metalize in vitro-developed biofilms or ex vivo clinical specimens colonized by biofilm-growing microorganisms are described as well as the advantages of the observation of these samples by field emission scanning electron microscopy.