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Sample records for scanning tunneling microscopic

  1. Scanning tunneling microscope nanoetching method

    DOEpatents

    Li, Yun-Zhong; Reifenberger, Ronald G.; Andres, Ronald P.

    1990-01-01

    A method is described for forming uniform nanometer sized depressions on the surface of a conducting substrate. A tunneling tip is used to apply tunneling current density sufficient to vaporize a localized area of the substrate surface. The resulting depressions or craters in the substrate surface can be formed in information encoding patterns readable with a scanning tunneling microscope.

  2. A Student-Built Scanning Tunneling Microscope

    ERIC Educational Resources Information Center

    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.…

  3. Scanning tunneling microscope assembly, reactor, and system

    SciTech Connect

    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.

  4. Design and calibration of a vacuum compatible scanning tunneling microscope

    NASA Technical Reports Server (NTRS)

    Abel, Phillip B.

    1990-01-01

    A vacuum compatible scanning tunneling microscope was designed and built, capable of imaging solid surfaces with atomic resolution. The single piezoelectric tube design is compact, and makes use of sample mounting stubs standard to a commercially available surface analysis system. Image collection and display is computer controlled, allowing storage of images for further analysis. Calibration results from atomic scale images are presented.

  5. Atomic and molecular manipulation with the scanning tunneling microscope.

    PubMed

    Stroscio, J A; Eigler, D M

    1991-11-29

    The prospect of manipulating matter on the atomic scale has fascinated scientists for decades. This fascination may be motivated by scientific and technological opportunities, or from a curiosity about the consequences of being able to place atoms in a particular location. Advances in scanning tunneling microscopy have made this prospect a reality; single atoms can be placed at selected positions and structures can be built to a particular design atom-by-atom. Atoms and molecules may be manipulated in a variety of ways by using the interactions present in the tunnel junction of a scanning tunneling microscope. Some of these recent developments and some of the possible uses of atomic and molecular manipulation as a tool for science are discussed.

  6. Scanning Tunneling Microscope Data Acquistion and Control System

    1995-02-01

    SHOESCAN is a PC based code that acquires and displays data for Scanning Tunneling Microscopes (STM). SHOESCAN interfaces with the STM through external electronic feedback and raster control circuits that are controlled by I/O boards on the PC bus. Data is displayed on a separate color monitor that is interfaced to the PC through an additional frame-grabber board. SHOESCAN can acquire a wide range of surface topographic information as well as surface electronic structure information.

  7. A combined apparatus of scanning reflection electron microscope and scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Maruno, S.; Nakahara, H.; Fujita, S.; Watanabe, H.; Kusumi, Y.; Ichikawa, M.

    1997-01-01

    A scanning reflection electron microscope (SREM) combined with a scanning tunneling microscope (STM) has been developed for the purpose of nanoscale structure fabrication under ultrahigh vacuum conditions. A STM unit consists of a piezoelectric tube scanner and an inch runner for coarse and fine approach of a STM tip. A sample holder and the STM unit have six drive axes relative to an electron gun for simultaneous observation by SREM and STM. Energy-dispersive x-ray spectroscopy equipment is also installed for surface sensitive elemental analysis. It has been demonstrated that on a Si(111)7×7 surface atomic steps and 7×7 unit, cells can be observed in the SREM and STM images, respectively, and that surface elements with less than 1 ML thickness are detectable.

  8. Theory of Visible Light Emission from Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Uehara, Yoichi; Kimura, Yuichi; Ushioda, Sukekatsu; Takeuchi, Koichiro

    1992-08-01

    The mechanism for visible light emission from the scanning tunneling microscope (STM) has been investigated theoretically by adapting a theory for light emitting tunnel junctions (LETJ). From the analysis of the calculated results and available experimental data, the following picture emerges. The tunneling current first excites localized surface plasmons (LSP) that are localized in a region of a few tens of Angstroms between the STM tip-front and the sample surface. Some of them decay into surface plasmon polaritons (SPP) that propagate along the sample surface. There are two channels of light emission: one is direct emission from LSP and the other is emission through SPP. The relative branching ratio between these two channels depends on the experimental configuration. The effect of sample surface roughness is very small and negligible.

  9. Scanning tunneling microscope with two-dimensional translator.

    PubMed

    Nichols, J; Ng, K-W

    2011-01-01

    Since the invention of the scanning tunneling microscope (STM), it has been a powerful tool for probing the electronic properties of materials. Typically STM designs capable of obtaining resolution on the atomic scale are limited to a small area which can be probed. We have built an STM capable of coarse motion in two dimensions, the z- and x-directions which are, respectively, parallel and perpendicular to the tip. This allows us to image samples with very high resolution at sites separated by macroscopic distances. This device is a single unit with a compact design making it very stable. It can operate in either a horizontal or vertical configuration and at cryogenic temperatures. PMID:21280836

  10. Scanning tunneling microscope with continuous flow cryostat sample cooling

    SciTech Connect

    Behler, S.; Rose, M.K.; Dunphy, J.C.; Ogletree, D.F.; Salmeron, M.; Chapelier, C.

    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.}

  11. A high stability and repeatability electrochemical scanning tunneling microscope

    SciTech Connect

    Xia, Zhigang; Wang, Jihao; Lu, Qingyou; Hou, Yubin

    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.

  12. Design and performance of a beetle-type double-tip scanning tunneling microscope

    SciTech Connect

    Jaschinsky, Philipp; Coenen, Peter; Pirug, Gerhard; Voigtlaender, Bert

    2006-09-15

    A combination of a double-tip scanning tunneling microscope with a scanning electron microscope in ultrahigh vacuum environment is presented. The compact beetle-type design made it possible to integrate two independently driven scanning tunneling microscopes in a small space. Moreover, an additional level for coarse movement allows the decoupling of the translation and approach of the tunneling tip. The position of the two tips can be controlled from the millimeter scale down to 50 nm with the help of an add-on electron microscope. The instrument is capable of atomic resolution imaging with each tip.

  13. Ni nanocrystals on HOPG(0001): A scanning tunnelling microscope study.

    PubMed

    Marz, Michael; Sagisaka, Keisuke; Fujita, Daisuke

    2013-01-01

    The growth mode of small Ni clusters evaporated in UHV on HOPG has been investigated by scanning tunnelling microscopy. The size, the size distribution, and the shape of the clusters have been evaluated for different evaporation conditions and annealing temperatures. The total coverage of the surface strongly depends on the evaporation rate and time, whereas the influence of these parameters is low on the cluster size. Subsequent stepwise annealing has been performed. This results in a reduction of the total amount of the Ni clusters accompanied by a decreasing in the overall coverage of the surface. The diameter of the clusters appears to be less influenced by the annealing than is their height. Besides this, the cluster shape is strongly influenced, changing to a quasi-hexagonal geometry after the first annealing step, indicating single-crystal formation. Finally, a reproducible methodology for picking up individual clusters is reported [1].

  14. Dual tunneling-unit scanning tunneling microscope for length measurement based on crystalline lattice

    SciTech Connect

    Zhang, H.; Higuchi, T.; Nishioki, N.

    1997-01-01

    A dual tunneling-unit scanning tunneling microscope (DTU STM) was developed for nm order length measurement with wide scan range. The crystalline lattice of highly oriented pyrolitic graphite (HOPG) was used as reference scale. A reference unit was set up on top of a test unit. The reference sample holder and the probe tip of test unit were attached to one single XY scanner on either surface, while the test sample holder was open. This enables simultaneous acquisition of wide images of HOPG and test sample. The length in test sample image was measured by counting the number of HOPG lattices. An inchworm actuator and an impact drive mechanism were introduced to roughly position probe tips. The XY scanner was designed to be elastic to eliminate image distortion. Some comparison experiments using two HOPG chips were carried out in air. The DTU STM is confirmed to be a stable and more powerful device for length measurement which has nanometer accuracy when covering a wide scan range up to several micrometers, and is capable of measuring comparatively large and heavy samples. {copyright} {ital 1997 American Vacuum Society.}

  15. Note: Long-range scanning tunneling microscope for the study of nanostructures on insulating substrates

    SciTech Connect

    Molina-Mendoza, Aday J.; Rodrigo, José G.; Rubio-Bollinger, Gabino; Island, Joshua; Burzuri, Enrique; Zant, Herre S. J. van der; Agraït, Nicolás

    2014-02-15

    The scanning tunneling microscope (STM) is a powerful tool for studying the electronic properties at the atomic level, however, it is of relatively small scanning range and the fact that it can only operate on conducting samples prevents its application to study heterogeneous samples consisting of conducting and insulating regions. Here we present a long-range scanning tunneling microscope capable of detecting conducting micro and nanostructures on insulating substrates using a technique based on the capacitance between the tip and the sample and performing STM studies.

  16. Local potentiometry using a multiprobe scanning tunneling microscope.

    PubMed

    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.

  17. Electronic Single Molecule Measurements with the Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Im, Jong One

    Richard Feynman said "There's plenty of room at the bottom". This inspired the techniques to improve the single molecule measurements. Since the first single molecule study was in 1961, it has been developed in various field and evolved into powerful tools to understand chemical and biological property of molecules. This thesis demonstrates electronic single molecule measurement with Scanning Tunneling Microscopy (STM) and two of applications of STM; Break Junction (BJ) and Recognition Tunneling (RT). First, the two series of carotenoid molecules with four different substituents were investigated to show how substituents relate to the conductance and molecular structure. The measured conductance by STM-BJ shows that Nitrogen induces molecular twist of phenyl distal substituents and conductivity increasing rather than Carbon. Also, the conductivity is adjustable by replacing the sort of residues at phenyl substituents. Next, amino acids and peptides were identified through STM-RT. The distribution of the intuitive features (such as amplitude or width) are mostly overlapped and gives only a little bit higher separation probability than random separation. By generating some features in frequency and cepstrum domain, the classification accuracy was dramatically increased. Because of large data size and many features, supporting vector machine (machine learning algorithm for big data) was used to identify the analyte from a data pool of all analytes RT data. The STM-RT opens a possibility of molecular sequencing in single molecule level. Similarly, carbohydrates were studied by STM-RT. Carbohydrates are difficult to read the sequence, due to their huge number of possible isomeric configurations. This study shows that STM-RT can identify not only isomers of mono-saccharides and disaccharides, but also various mono-saccharides from a data pool of eleven analytes. In addition, the binding affinity between recognition molecule and analyte was investigated by comparing with

  18. A cryogen-free variable temperature scanning tunneling microscope capable for inelastic electron tunneling spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Huang, Di; Wu, Shiwei

    While low temperature scanning tunneling microscope (STM) has become an indispensable research tool in surface science, its versatility is yet limited by the shortage or high cost of liquid helium. The makeshifts include the use of alternative cryogen (such as liquid nitrogen) at higher temperature or the development of helium liquefier system usually at departmental or campus wide. The ultimate solution would be the direct integration of a cryogen-free cryocooler based on GM or pulse tube closed cycle in the STM itself. However, the nasty mechanical vibration at low frequency intrinsic to cryocoolers has set the biggest obstacle because of the known challenges in vibration isolation required to high performance of STM. In this talk, we will present the design and performance of our home-built cryogen-free variable temperature STM at Fudan University. This system can obtain atomically sharp STM images and high resolution dI/dV spectra comparable to state-of-the-art low temperature STMs, but with no limitation on running hours. Moreover, we demonstrated the inelastic tunneling spectroscopy (STM-IETS) on a single CO molecule with a cryogen-free STM for the first time.

  19. A cryogen-free low temperature scanning tunneling microscope capable of inelastic electron tunneling spectroscopy.

    PubMed

    Zhang, Shuai; Huang, Di; Wu, Shiwei

    2016-06-01

    The design and performance of a cryogen-free low temperature scanning tunneling microscope (STM) housed in ultrahigh vacuum (UHV) are reported. The cryogen-free design was done by directly integrating a Gifford-McMahon cycle cryocooler to a Besocke-type STM, and the vibration isolation was achieved by using a two-stage rubber bellow between the cryocooler and a UHV-STM interface with helium exchange gas cooling. A base temperature of 15 K at the STM was achieved, with a possibility to further decrease by using a cryocooler with higher cooling power and adding additional low temperature stage under the exchange gas interface. Atomically sharp STM images and high resolution dI/dV spectra on various samples were demonstrated. Furthermore, we reported the inelastic tunneling spectroscopy on a single carbon monoxide molecule adsorbed on Ag(110) surface with a cryogen-free STM for the first time. Being totally cryogen-free, the system not only saves the running cost significantly but also enables uninterrupted data acquisitions and variable temperature measurements with much ease. In addition, the system is capable of coupling light to the STM junction by a pair of lens inside the UHV chamber. We expect that these enhanced capabilities could further broaden our views to the atomic-scale world.

  20. A cryogen-free low temperature scanning tunneling microscope capable of inelastic electron tunneling spectroscopy.

    PubMed

    Zhang, Shuai; Huang, Di; Wu, Shiwei

    2016-06-01

    The design and performance of a cryogen-free low temperature scanning tunneling microscope (STM) housed in ultrahigh vacuum (UHV) are reported. The cryogen-free design was done by directly integrating a Gifford-McMahon cycle cryocooler to a Besocke-type STM, and the vibration isolation was achieved by using a two-stage rubber bellow between the cryocooler and a UHV-STM interface with helium exchange gas cooling. A base temperature of 15 K at the STM was achieved, with a possibility to further decrease by using a cryocooler with higher cooling power and adding additional low temperature stage under the exchange gas interface. Atomically sharp STM images and high resolution dI/dV spectra on various samples were demonstrated. Furthermore, we reported the inelastic tunneling spectroscopy on a single carbon monoxide molecule adsorbed on Ag(110) surface with a cryogen-free STM for the first time. Being totally cryogen-free, the system not only saves the running cost significantly but also enables uninterrupted data acquisitions and variable temperature measurements with much ease. In addition, the system is capable of coupling light to the STM junction by a pair of lens inside the UHV chamber. We expect that these enhanced capabilities could further broaden our views to the atomic-scale world. PMID:27370453

  1. Making Mn substitutional impurities in InAs using a scanning tunneling microscope.

    PubMed

    Song, Young Jae; Erwin, Steven C; Rutter, Gregory M; First, Phillip N; Zhitenev, Nikolai B; Stroscio, Joseph A

    2009-12-01

    We describe in detail an atom-by-atom exchange manipulation technique using a scanning tunneling microscope probe. As-deposited Mn adatoms (Mn(ad)) are exchanged one-by-one with surface In atoms (In(su)) to create a Mn surface-substitutional (Mn(In)) and an exchanged In adatom (In(ad)) by an electron tunneling induced reaction Mn(ad) + In(su) --> Mn(In) + In(ad) on the InAs(110) surface. In combination with density-functional theory and high resolution scanning tunneling microscopy imaging, we have identified the reaction pathway for the Mn and In atom exchange.

  2. Method to characterize the vibrational response of a beetle type scanning tunneling microscope

    SciTech Connect

    Behler, S.; Rose, M.K.; Ogletree, D.F.; Salmeron, M.

    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.}

  3. Partial sequencing of a single DNA molecule with a scanning tunnelling microscope

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroyuki; Kawai, Tomoji

    2009-08-01

    The scanning tunnelling microscope is capable of the real-space imaging and spectroscopy of molecules on an atomic scale. Numerous attempts have been made to use the scanning tunnelling microscope to sequence single DNA molecules, but difficulties in preparing samples of long-chain DNA molecules on surfaces, and problems in reproducing results have limited these experiments. Here, we report single-molecule DNA sequencing with a scanning tunnelling microscope by using an oblique pulse-injection method to deposit the molecules onto a copper surface. First, we show that guanine bases have a distinct electronic state that allows them to be distinguished from the other nucleic acid bases. Then, by comparing data on M13mp18, a single-stranded phage DNA, with a known base sequence, the `electronic fingerprint' of guanine bases in the DNA molecule is identified. These results show that it is possible to sequence individual guanine bases in real long-chain DNA molecules with high-resolution scanning tunnelling microscope imaging and spectroscopy.

  4. In Situ Observation and Selective Electrochemical Deposition of Polypyrrole by Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Sasano, Kiyotaka; Nakamura, Kazunori; Kaneto, Keiichi

    1993-06-01

    Electrodeposition of polypyrrole and its selective deposition on a highly oriented pyrolytic graphite substrate was observed in situ by means of scanning tunneling microscope (STM) in an electrochemical cell. The results indicated that the STM can be used to manipulate the electrodeposition of conducting polymers.

  5. The initiation and characterization of single bimolecular reactions with a scanning tunneling microscope.

    PubMed

    Lauhon, L J; Ho, W

    2000-01-01

    A scanning tunneling microscope (STM) operating at 9 K in ultrahigh vacuum was used to initiate a bimolecular reaction between isolated hydrogen sulfide and dicarbon molecules on the Cu(001) surface. The reaction products ethynyl (CCH) and sulfhydryl (SH) were identified by inelastic electron tunneling spectroscopy (STM-IETS) and by sequentially removing hydrogen atoms from an H2S molecule using energetic tunneling electrons. For comparison, the thermal diffusion and reaction of H2S and CC at 45 K and H2O and CC at 9 K were also observed.

  6. Selective scanning tunneling microscope light emission from rutile phase of VO2.

    PubMed

    Sakai, Joe; Kuwahara, Masashi; Hotsuki, Masaki; Katano, Satoshi; Uehara, Yoichi

    2016-09-28

    We observed scanning tunneling microscope light emission (STM-LE) induced by a tunneling current at the gap between an Ag tip and a VO2 thin film, in parallel to scanning tunneling spectroscopy (STS) profiles. The 34 nm thick VO2 film grown on a rutile TiO2 (0 0 1) substrate consisted of both rutile (R)- and monoclinic (M)-structure phases of a few 10 nm-sized domains at room temperature. We found that STM-LE with a certain photon energy of 2.0 eV occurs selectively from R-phase domains of VO2, while no STM-LE was observed from M-phase. The mechanism of STM-LE from R-phase VO2 was determined to be an interband transition process rather than inverse photoemission or inelastic tunneling processes. PMID:27460183

  7. Selective scanning tunneling microscope light emission from rutile phase of VO2

    NASA Astrophysics Data System (ADS)

    Sakai, Joe; Kuwahara, Masashi; Hotsuki, Masaki; Katano, Satoshi; Uehara, Yoichi

    2016-09-01

    We observed scanning tunneling microscope light emission (STM-LE) induced by a tunneling current at the gap between an Ag tip and a VO2 thin film, in parallel to scanning tunneling spectroscopy (STS) profiles. The 34 nm thick VO2 film grown on a rutile TiO2 (0 0 1) substrate consisted of both rutile (R)- and monoclinic (M)-structure phases of a few 10 nm-sized domains at room temperature. We found that STM-LE with a certain photon energy of 2.0 eV occurs selectively from R-phase domains of VO2, while no STM-LE was observed from M-phase. The mechanism of STM-LE from R-phase VO2 was determined to be an interband transition process rather than inverse photoemission or inelastic tunneling processes.

  8. A variable temperature scanning tunneling microscope for the study of surface reactions in ultrahigh vacuum

    NASA Astrophysics Data System (ADS)

    Crew, William W.; Madix, Robert J.

    1995-09-01

    The design and performance of a variable temperature, controlled atmosphere ultrahigh-vacuum scanning tunneling microscope (STM) system useful for the study of reactions on surfaces is described. The system incorporates a scanning tunneling microscope of the ``Johnnie Walker'' type into a versatile UHV system equipped with other diagnostic equipment necessary for studies of surface reactivity. The design is compatible with the combination of a wide variety of surface science measurements with STM. Vibration isolation of the microscope is simply accomplished by use of laminar flow isolation legs and inertial decoupling of the sample from the environment. Atomic resolution on metals can be achieved at temperatures between 125 and 400 K with a combination of continuous liquid-nitrogen cooling and radiative heating of the sample.

  9. Field emission current-voltage curves as a diagnostic for scanning tunneling microscope tips

    NASA Astrophysics Data System (ADS)

    Meyer, J. A.; Stranick, S. J.; Wang, J. B.; Weiss, P. S.

    1991-12-01

    The current-voltage (I-V) characteristics of a low temperature ultrahigh vacuum scanning tunneling microscope (STM) tip positioned greater than 100 A from a planar surface have been recorded. We find curvature in the Fowler-Nordheim plots (log 10 I/V(sup 2) vs. I/V) due to the tip-plane geometry as has been predicted theoretically. Additionally, oscillations and sharp breaks in these I-V curves are observed over a wide voltage range, 50-1000 V. These I-V curves are used to characterize the STM tips prior to tunneling.

  10. A variable-temperature nanostencil compatible with a low-temperature scanning tunneling microscope/atomic force microscope

    SciTech Connect

    Steurer, Wolfram Gross, Leo; Schlittler, Reto R.; Meyer, Gerhard

    2014-02-15

    We describe a nanostencil lithography tool capable of operating at variable temperatures down to 30 K. The setup is compatible with a combined low-temperature scanning tunneling microscope/atomic force microscope located within the same ultra-high-vacuum apparatus. The lateral movement capability of the mask allows the patterning of complex structures. To demonstrate operational functionality of the tool and estimate temperature drift and blurring, we fabricated LiF and NaCl nanostructures on Cu(111) at 77 K.

  11. Magnetic nanostructures fabricated by scanning tunneling microscope-assisted chemical vapor deposition

    SciTech Connect

    Pai, W.W.; Zhang, J.; Wendelken, J.F.; Warmack, R.J.

    1997-07-01

    We have successfully used scanning tunneling microscope-assisted chemical vapor deposition to fabricate magnetic nanostructures as fine as 5 nm wide and {lt}2 nm high using ferrocene [Fe(C{sub 5}H{sub 5}){sub 2}] as the metal-organic source gas. The physical properties of these nanostructures were qualitatively characterized and {ital ex situ} magnetic force microscopy measurements indicate these features are strongly magnetic.

  12. Four-probe measurements with a three-probe scanning tunneling microscope

    SciTech Connect

    Salomons, Mark; Martins, Bruno V. C.; Zikovsky, Janik; Wolkow, Robert A.

    2014-04-15

    We present an ultrahigh vacuum (UHV) three-probe scanning tunneling microscope in which each probe is capable of atomic resolution. A UHV JEOL scanning electron microscope aids in the placement of the probes on the sample. The machine also has a field ion microscope to clean, atomically image, and shape the probe tips. The machine uses bare conductive samples and tips with a homebuilt set of pliers for heating and loading. Automated feedback controlled tip-surface contacts allow for electrical stability and reproducibility while also greatly reducing tip and surface damage due to contact formation. The ability to register inter-tip position by imaging of a single surface feature by multiple tips is demonstrated. Four-probe material characterization is achieved by deploying two tips as fixed current probes and the third tip as a movable voltage probe.

  13. Nanomanipulation and nanofabrication with multi-probe scanning tunneling microscope: From individual atoms to nanowires

    NASA Astrophysics Data System (ADS)

    Qin, Shengyong; Kim, Tae-Hwan; Wang, Zhouhang; Li, An-Ping

    2012-06-01

    The wide variety of nanoscale structures and devices demands novel tools for handling, assembly, and fabrication at nanoscopic positioning precision. The manipulation tools should allow for in situ characterization and testing of fundamental building blocks, such as nanotubes and nanowires, as they are built into functional devices. In this paper, a bottom-up technique for nanomanipulation and nanofabrication is reported by using a 4-probe scanning tunneling microscope (STM) combined with a scanning electron microscope (SEM). The applications of this technique are demonstrated in a variety of nanosystems, from manipulating individual atoms to bending, cutting, breaking carbon nanofibers, and constructing nanodevices for electrical characterizations. The combination of the wide field of view of SEM, the atomic position resolution of STM, and the flexibility of multiple scanning probes is expected to be a valuable tool for rapid prototyping in the nanoscience and nanotechnology.

  14. Current–Voltage Characterization of Individual As-Grown Nanowires Using a Scanning Tunneling Microscope

    PubMed Central

    2013-01-01

    Utilizing semiconductor nanowires for (opto)electronics requires exact knowledge of their current–voltage properties. We report accurate on-top imaging and I–V characterization of individual as-grown nanowires, using a subnanometer resolution scanning tunneling microscope with no need for additional microscopy tools, thus allowing versatile application. We form Ohmic contacts to InP and InAs nanowires without any sample processing, followed by quantitative measurements of diameter dependent I–V properties with a very small spread in measured values compared to standard techniques. PMID:24059470

  15. Plasmon-mediated circularly polarized luminescence of GaAs in a scanning tunneling microscope

    SciTech Connect

    Mühlenberend, Svenja; Gruyters, Markus; Berndt, Richard

    2015-12-14

    The electroluminescence from p-type GaAs(110) in a scanning tunneling microscope has been investigated at 6 K. Unexpectedly, high degrees of circular polarization have often been observed with ferromagnetic Ni tips and also with paramagnetic W and Ag tips. The data are interpreted in terms of two distinct excitation mechanisms. Electron injection generates intense luminescence with low polarization. Plasmon-mediated generation of electron-hole pairs leads to less intense emission, which, however, is highly polarized for many tips.

  16. A scanning tunneling microscope break junction method with continuous bias modulation.

    PubMed

    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. PMID:26308622

  17. Magnetic fingerprint of individual Fe4 molecular magnets under compression by a scanning tunnelling microscope

    PubMed Central

    Burgess, Jacob A.J.; Malavolti, Luigi; Lanzilotto, Valeria; Mannini, Matteo; Yan, Shichao; Ninova, Silviya; Totti, Federico; Rolf-Pissarczyk, Steffen; Cornia, Andrea; Sessoli, Roberta; Loth, Sebastian

    2015-01-01

    Single-molecule magnets (SMMs) present a promising avenue to develop spintronic technologies. Addressing individual molecules with electrical leads in SMM-based spintronic devices remains a ubiquitous challenge: interactions with metallic electrodes can drastically modify the SMM's properties by charge transfer or through changes in the molecular structure. Here, we probe electrical transport through individual Fe4 SMMs using a scanning tunnelling microscope at 0.5 K. Correlation of topographic and spectroscopic information permits identification of the spin excitation fingerprint of intact Fe4 molecules. Building from this, we find that the exchange coupling strength within the molecule's magnetic core is significantly enhanced. First-principles calculations support the conclusion that this is the result of confinement of the molecule in the two-contact junction formed by the microscope tip and the sample surface. PMID:26359203

  18. Magnetic fingerprint of individual Fe4 molecular magnets under compression by a scanning tunnelling microscope.

    PubMed

    Burgess, Jacob A J; Malavolti, Luigi; Lanzilotto, Valeria; Mannini, Matteo; Yan, Shichao; Ninova, Silviya; Totti, Federico; Rolf-Pissarczyk, Steffen; Cornia, Andrea; Sessoli, Roberta; Loth, Sebastian

    2015-09-11

    Single-molecule magnets (SMMs) present a promising avenue to develop spintronic technologies. Addressing individual molecules with electrical leads in SMM-based spintronic devices remains a ubiquitous challenge: interactions with metallic electrodes can drastically modify the SMM's properties by charge transfer or through changes in the molecular structure. Here, we probe electrical transport through individual Fe4 SMMs using a scanning tunnelling microscope at 0.5 K. Correlation of topographic and spectroscopic information permits identification of the spin excitation fingerprint of intact Fe4 molecules. Building from this, we find that the exchange coupling strength within the molecule's magnetic core is significantly enhanced. First-principles calculations support the conclusion that this is the result of confinement of the molecule in the two-contact junction formed by the microscope tip and the sample surface.

  19. Scanning tunneling microscope light emission: Effect of the strong dc field on junction plasmons

    NASA Astrophysics Data System (ADS)

    Kalathingal, Vijith; Dawson, Paul; Mitra, J.

    2016-07-01

    The observed energies of the localized surface plasmons (LSPs) excited at the tip-sample junction of a scanning tunneling microscope, as identified by spectral peaks in the light output, are very significantly redshifted with respect to calculations that use standard optical data for the tip and sample material, gold in this case. We argue that this anomaly depends on the extreme field in the sub-nm tunneling proximity of the tip and the sample, across which a dc bias (1-2 V) is applied. Finite element modeling analysis is presented of a gold nanosphere-plane (NS-P) combination in tunneling proximity and, crucially, in the presence of a high static electric field (˜109V /m ). It is argued that the strong dc field induces nonlinear corrections to the dielectric function of the gold via the effect of a large background polarizability through the nonlinear, χ(3 ) susceptibility contribution. When fed into the model system the modified optical data alters the LSP cavity modes of the NS-P system to indeed reveal a large redshift in energy compared to those of the virgin gold NS-P system. The net outcome may be regarded as equivalent to lowering the bulk plasmon energy, the physical interpretation being that the intense field of the tunneling environment leads to surface charge screening, effectively reducing the density of free electrons available to participate in the plasmon oscillations.

  20. Direct measurement of standing evanescent waves with a photon-scanning tunneling microscope.

    PubMed

    Meixner, A J; Bopp, M A; Tarrach, G

    1994-12-01

    We present a detailed analysis of a standing evanescent wave that is caused by total internal reflection of an Ar-ion laser beam on a glass prism and investigate the coupling to a subwavelength dielectric tip of a photon-scanning tunneling microscope that is raster scanned at a close distance over the prism surface. The intensity of the evanescent field is spatially modulated with a period of 239.2 nm. It decays exponentially with a constant of 103.9 nm with increasing distance from the prism surface. Precise measurements of the standing evanescent wave can be used to calibrate the scanner and permit one to determine the spatial resolution and the coupling efficiency of the tip.

  1. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope.

    PubMed

    Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

    2016-08-01

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam. PMID:27587179

  2. Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope.

    PubMed

    Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

    2016-08-01

    We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

  3. Scanning tunneling microscope design with a confocal small field permanent magnet.

    SciTech Connect

    Messina, P.; Pearson, J.; Vasserman, I.; Sasaki, S.; Moog, E.; Fradin, F.

    2008-09-01

    The field of ultra-sensitive measurements with scanning probes requires the design and construction of novel instruments. For example, the combination of radio frequency detection and scanning probe can be exploited to measure thermal properties and mechanical resonances at a very low scale. Very recent results by Komeda and Manassen (2008 Appl. Phys. Lett. 92 212506) on the detection of spin noise with the scanning tunneling microscopy (STM) have further expanded previous results reported by one of the authors of this manuscript (Messina et al 2007 J. Appl. Phys. 101 053916). In a previous publication, one of the authors used a new STM instrument (Messina et al J. Appl. Phys. 2007 101 053916 and Mannini et al 2007 Inorg. Chim. Acta 360 3837-42) to obtain the detection of electron spin noise (ESN) from individual paramagnetic adsorbates. The magnetic field homogeneity at the STM tip-sample region was limited. Furthermore, vacuum operation of the STM microscope was limited by the heat dissipation at the electromagnet and the radio frequency (RF) recovery electronics. We report here on a new STM head that incorporates a specially designed permanent magnet and in-built RF amplification system. The magnet provides both a better field homogeneity and freedom to operate the instrument in vacuum. The STM microscope is vacuum compatible, and vertical stability has been improved over the previous design (Messina et al 2007 J. Appl. Phys. 101 053916), despite the presence of a heat dissipative RF amplifier in the close vicinity of the STM tip.

  4. Scanning magnetic tunnel junction microscope for high-resolution imaging of remanent magnetization fields

    NASA Astrophysics Data System (ADS)

    Lima, E. A.; Bruno, A. C.; Carvalho, H. R.; Weiss, B. P.

    2014-10-01

    Scanning magnetic microscopy is a new methodology for mapping magnetic fields with high spatial resolution and field sensitivity. An important goal has been to develop high-performance instruments that do not require cryogenic technology due to its high cost, complexity, and limitation on sensor-to-sample distance. Here we report the development of a low-cost scanning magnetic microscope based on commercial room-temperature magnetic tunnel junction (MTJ) sensors that typically achieves spatial resolution better than 7 µm. By comparing different bias and detection schemes, optimal performance was obtained when biasing the MTJ sensor with a modulated current at 1.0 kHz in a Wheatstone bridge configuration while using a lock-in amplifier in conjunction with a low-noise custom-made preamplifier. A precision horizontal (x-y) scanning stage comprising two coupled nanopositioners controls the position of the sample and a linear actuator adjusts the sensor-to-sample distance. We obtained magnetic field sensitivities better than 150 nT/Hz1/2 between 0.1 and 10 Hz, which is a critical frequency range for scanning magnetic microscopy. This corresponds to a magnetic moment sensitivity of 10-14 A m2, a factor of 100 better than achievable with typical commercial superconducting moment magnetometers. It also represents an improvement in sensitivity by a factor between 10 and 30 compared to similar scanning MTJ microscopes based on conventional bias-detection schemes. To demonstrate the capabilities of the instrument, two polished thin sections of representative geological samples were scanned along with a synthetic sample containing magnetic microparticles. The instrument is usable for a diversity of applications that require mapping of samples at room temperature to preserve magnetic properties or viability, including paleomagnetism and rock magnetism, nondestructive evaluation of materials, and biological assays.

  5. Calibration of tip and sample temperature of a scanning tunneling microscope using a superconductive sample

    SciTech Connect

    Stocker, Matthias; Pfeifer, Holger; Koslowski, Berndt

    2014-05-15

    The temperature of the electrodes is a crucial parameter in virtually all tunneling experiments. The temperature not only controls the thermodynamic state of the electrodes but also causes thermal broadening, which limits the energy resolution. Unfortunately, the construction of many scanning tunneling microscopes inherits a weak thermal link between tip and sample in order to make one side movable. Such, the temperature of that electrode is badly defined. Here, the authors present a procedure to calibrate the tip temperature by very simple means. The authors use a superconducting sample (Nb) and a standard tip made from W. Due to the asymmetry in the density of states of the superconductor (SC)—normal metal (NM) tunneling junction, the SC temperature controls predominantly the density of states while the NM controls the thermal smearing. By numerically simulating the I-V curves and numerically optimizing the tip temperature and the SC gap width, the tip temperature can be accurately deduced if the sample temperature is known or measureable. In our case, the temperature dependence of the SC gap may serve as a temperature sensor, leading to an accurate NM temperature even if the SC temperature is unknown.

  6. A scanning tunneling microscope capable of imaging specified micron-scale small samples

    NASA Astrophysics Data System (ADS)

    Tao, Wei; Cao, Yufei; Wang, Huafeng; Wang, Kaiyou; Lu, Qingyou

    2012-12-01

    We present a home-built scanning tunneling microscope (STM) which allows us to precisely position the tip on any specified small sample or sample feature of micron scale. The core structure is a stand-alone soft junction mechanical loop (SJML), in which a small piezoelectric tube scanner is mounted on a sliding piece and a "U"-like soft spring strip has its one end fixed to the sliding piece and its opposite end holding the tip pointing to the sample on the scanner. Here, the tip can be precisely aligned to a specified small sample of micron scale by adjusting the position of the spring-clamped sample on the scanner in the field of view of an optical microscope. The aligned SJML can be transferred to a piezoelectric inertial motor for coarse approach, during which the U-spring is pushed towards the sample, causing the tip to approach the pre-aligned small sample. We have successfully approached a hand cut tip that was made from 0.1 mm thin Pt/Ir wire to an isolated individual 32.5 × 32.5 μm2 graphite flake. Good atomic resolution images and high quality tunneling current spectra for that specified tiny flake are obtained in ambient conditions with high repeatability within one month showing high and long term stability of the new STM structure. In addition, frequency spectra of the tunneling current signals do not show outstanding tip mount related resonant frequency (low frequency), which further confirms the stability of the STM structure.

  7. Development of Novel System Combining Scanning Tunneling Microscope-Based Cathodoluminescence and Electroluminescence Nanospectroscopies

    NASA Astrophysics Data System (ADS)

    Watanabe, Kentaro; Nakamura, Yoshiaki; Kuboya, Shigeyuki; Katayama, Ryuji; Onabe, Kentaro; Ichikawa, Masakazu

    2011-08-01

    Novel system equipped with conductive optical fiber probe scanning tunneling microscope (STM) and bipolar sample holder is a powerful tool to characterize light-emitting devices by several STM-based techniques at the same sample position, which can realize photoluminescence (PL), cathodoluminescence (CL), electroluminescence (EL), and electron beam induced current (EBIC) measurements with higher spatial resolutions than conventional techniques. In this study, we developed a STM-CL/EL system which combines STM-CL technique for high CL excitation power and high spatial resolution and STM-EL technique for local EL collection. We demonstrated spatially resolved STM-CL/EL spectroscopy of GaAs/AlGaAs heterostructure (110) cross-sections.

  8. Invited Article: Autonomous assembly of atomically perfect nanostructures using a scanning tunneling microscope

    SciTech Connect

    Celotta, Robert J. E-mail: joseph.stroscio@nist.gov; Hess, Frank M.; Rutter, Gregory M.; Stroscio, Joseph A. E-mail: joseph.stroscio@nist.gov; Balakirsky, Stephen B.; Fein, Aaron P.

    2014-12-15

    A major goal of nanotechnology is to develop the capability to arrange matter at will by placing individual atoms at desired locations in a predetermined configuration to build a nanostructure with specific properties or function. The scanning tunneling microscope has demonstrated the ability to arrange the basic building blocks of matter, single atoms, in two-dimensional configurations. An array of various nanostructures has been assembled, which display the quantum mechanics of quantum confined geometries. The level of human interaction needed to physically locate the atom and bring it to the desired location limits this atom assembly technology. Here we report the use of autonomous atom assembly via path planning technology; this allows atomically perfect nanostructures to be assembled without the need for human intervention, resulting in precise constructions in shorter times. We demonstrate autonomous assembly by assembling various quantum confinement geometries using atoms and molecules and describe the benefits of this approach.

  9. Structure investigation of Cellobiohydrolase I from Trichoderma pseudokoningii S38 with a scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Z.; Liu, J.; Gao, P. J.; Ma, L. P.; Shi, D. X.; Pang, S. J.

    Cellobiohydrolase I (CBH I) was isolated from a cellulolytic fungal strain Trichoderma pseudokoningii S38, and its ultrastructure was investigated with a scanning tunneling microscope (STM). The STM images showed that the shape of intact CBH I was tadpole-like, consisting of a big head and a long tail. It could be deduced that the head domain was the core protein for the catalytic function, and the long tail was the cellulose binding domain for substrate binding. Thus, for this enzyme molecule, functional differentiation is reflected in the structure peculiarities. This is the first direct observation of the three-dimensional structure of intact CBH I from real space at nanometer scale. The functional mechanism is also discussed.

  10. Low-temperature-compatible tunneling-current-assisted scanning microwave microscope utilizing a rigid coaxial resonator.

    PubMed

    Takahashi, Hideyuki; Imai, Yoshinori; Maeda, Atsutaka

    2016-06-01

    We present a design for a tunneling-current-assisted scanning near-field microwave microscope. For stable operation at cryogenic temperatures, making a small and rigid microwave probe is important. Our coaxial resonator probe has a length of approximately 30 mm and can fit inside the 2-in. bore of a superconducting magnet. The probe design includes an insulating joint, which separates DC and microwave signals without degrading the quality factor. By applying the SMM to the imaging of an electrically inhomogeneous superconductor, we obtain the spatial distribution of the microwave response with a spatial resolution of approximately 200 nm. Furthermore, we present an analysis of our SMM probe based on a simple lumped-element circuit model along with the near-field microwave measurements of silicon wafers having different conductivities. PMID:27370458

  11. In situ scanning tunneling microscope tip treatment device for spin polarization imaging

    SciTech Connect

    Li, An-Ping; Jianxing, Ma; Shen, Jian

    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.

  12. Design and Implementation of a 4K Cryocooler-Based Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Vishnubhotla, Ramya; Harrington, Neal; Dusch, Bill; Geng, Carrie; Bannerjee, Riju; Pabbi, Lavish; Hudson, Eric W.

    2013-03-01

    Low temperature, ultra-high vacuum scanning tunneling microscopes (STMs) have proved to be excellent tools for the study of electronic properties of complex materials. Unfortunately, with the continuing increase in liquid helium prices, already a dominant cost for operating these systems, their use is becoming exceedingly expensive. Here we describe the design and implementation of a STM cooled by a Cryomech PT407 Remote Motor Cryorefrigerator, allowing us to reach helium temperatures using a closed thermodynamic cycle with zero cryogen waste. Unfortunately, this refrigeration technique is not ultra-high vacuum (UHV) compatible and introduces vibrations. To tackle these problems, we separately house the cryocooler in a high-vacuum (HV) chamber. This provides both a UHV environment for the STM and mechanical isolation to minimize vibrations reaching the instrument. However, it makes for more challenging thermal connections. This last difficulty we solve by introducing a novel coaxial thermal feedthrough between the HV and UHV chambers. Supported by NSF DMR-0904400

  13. Low-temperature-compatible tunneling-current-assisted scanning microwave microscope utilizing a rigid coaxial resonator

    NASA Astrophysics Data System (ADS)

    Takahashi, Hideyuki; Imai, Yoshinori; Maeda, Atsutaka

    2016-06-01

    We present a design for a tunneling-current-assisted scanning near-field microwave microscope. For stable operation at cryogenic temperatures, making a small and rigid microwave probe is important. Our coaxial resonator probe has a length of approximately 30 mm and can fit inside the 2-in. bore of a superconducting magnet. The probe design includes an insulating joint, which separates DC and microwave signals without degrading the quality factor. By applying the SMM to the imaging of an electrically inhomogeneous superconductor, we obtain the spatial distribution of the microwave response with a spatial resolution of approximately 200 nm. Furthermore, we present an analysis of our SMM probe based on a simple lumped-element circuit model along with the near-field microwave measurements of silicon wafers having different conductivities.

  14. Invited Article: Autonomous assembly of atomically perfect nanostructures using a scanning tunneling microscope.

    PubMed

    Celotta, Robert J; Balakirsky, Stephen B; Fein, Aaron P; Hess, Frank M; Rutter, Gregory M; Stroscio, Joseph A

    2014-12-01

    A major goal of nanotechnology is to develop the capability to arrange matter at will by placing individual atoms at desired locations in a predetermined configuration to build a nanostructure with specific properties or function. The scanning tunneling microscope has demonstrated the ability to arrange the basic building blocks of matter, single atoms, in two-dimensional configurations. An array of various nanostructures has been assembled, which display the quantum mechanics of quantum confined geometries. The level of human interaction needed to physically locate the atom and bring it to the desired location limits this atom assembly technology. Here we report the use of autonomous atom assembly via path planning technology; this allows atomically perfect nanostructures to be assembled without the need for human intervention, resulting in precise constructions in shorter times. We demonstrate autonomous assembly by assembling various quantum confinement geometries using atoms and molecules and describe the benefits of this approach. PMID:25554264

  15. Invited Article: Autonomous assembly of atomically perfect nanostructures using a scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Celotta, Robert J.; Balakirsky, Stephen B.; Fein, Aaron P.; Hess, Frank M.; Rutter, Gregory M.; Stroscio, Joseph A.

    2014-12-01

    A major goal of nanotechnology is to develop the capability to arrange matter at will by placing individual atoms at desired locations in a predetermined configuration to build a nanostructure with specific properties or function. The scanning tunneling microscope has demonstrated the ability to arrange the basic building blocks of matter, single atoms, in two-dimensional configurations. An array of various nanostructures has been assembled, which display the quantum mechanics of quantum confined geometries. The level of human interaction needed to physically locate the atom and bring it to the desired location limits this atom assembly technology. Here we report the use of autonomous atom assembly via path planning technology; this allows atomically perfect nanostructures to be assembled without the need for human intervention, resulting in precise constructions in shorter times. We demonstrate autonomous assembly by assembling various quantum confinement geometries using atoms and molecules and describe the benefits of this approach.

  16. Gap Measurement of Na2IrO3 with a Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Ansary, Armin; Nichols, John; Cao, Gang; Ng, Kwok-Wai

    2015-03-01

    5d transition metal oxides such as iridates have recently stimulated substantial interest. Many exciting new phases can be found in this class of materials because of the comparable strength between spin-orbit coupling and the Coulomb interaction. In particular, we have studied high quality single crystal Na2IrO3 with a scanning tunneling microscope (STM). Na2IrO3 has a layered structure with a honeycomb lattice. The gap is measured to be about 400 meV according to the dI/dV curve, which is consistent with optical measurements. We will show topographic images and discuss the evolution of the density of states and the behavior of the gap from room temperature down to 100 K. This work was supported by the National Science Foundation under Grant DMR-1265162.

  17. Invited Article: Autonomous assembly of atomically perfect nanostructures using a scanning tunneling microscope.

    PubMed

    Celotta, Robert J; Balakirsky, Stephen B; Fein, Aaron P; Hess, Frank M; Rutter, Gregory M; Stroscio, Joseph A

    2014-12-01

    A major goal of nanotechnology is to develop the capability to arrange matter at will by placing individual atoms at desired locations in a predetermined configuration to build a nanostructure with specific properties or function. The scanning tunneling microscope has demonstrated the ability to arrange the basic building blocks of matter, single atoms, in two-dimensional configurations. An array of various nanostructures has been assembled, which display the quantum mechanics of quantum confined geometries. The level of human interaction needed to physically locate the atom and bring it to the desired location limits this atom assembly technology. Here we report the use of autonomous atom assembly via path planning technology; this allows atomically perfect nanostructures to be assembled without the need for human intervention, resulting in precise constructions in shorter times. We demonstrate autonomous assembly by assembling various quantum confinement geometries using atoms and molecules and describe the benefits of this approach.

  18. Imaging sequential dehydrogenation of methanol on Cu(110) with a scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Kitaguchi, Y.; Shiotari, A.; Okuyama, H.; Hatta, S.; Aruga, T.

    2011-05-01

    Adsorption of methanol and its dehydrogenation on Cu(110) were studied by using a scanning tunneling microscope (STM). Upon adsorption at 12 K, methanol preferentially forms clusters on the surface. The STM could induce dehydrogenation of methanol sequentially to methoxy and formaldehyde. This enabled us to study the binding structures of these products in a single-molecule limit. Methoxy was imaged as a pair of protrusion and depression along the [001] direction. This feature is fully consistent with the previous result that it adsorbs on the short-bridge site with the C-O axis tilted along the [001] direction. The axis was induced to flip back and forth by vibrational excitations with the STM. Two configurations were observed for formaldehyde, whose structures were proposed based on their characteristic images and motions.

  19. Low-temperature-compatible tunneling-current-assisted scanning microwave microscope utilizing a rigid coaxial resonator.

    PubMed

    Takahashi, Hideyuki; Imai, Yoshinori; Maeda, Atsutaka

    2016-06-01

    We present a design for a tunneling-current-assisted scanning near-field microwave microscope. For stable operation at cryogenic temperatures, making a small and rigid microwave probe is important. Our coaxial resonator probe has a length of approximately 30 mm and can fit inside the 2-in. bore of a superconducting magnet. The probe design includes an insulating joint, which separates DC and microwave signals without degrading the quality factor. By applying the SMM to the imaging of an electrically inhomogeneous superconductor, we obtain the spatial distribution of the microwave response with a spatial resolution of approximately 200 nm. Furthermore, we present an analysis of our SMM probe based on a simple lumped-element circuit model along with the near-field microwave measurements of silicon wafers having different conductivities.

  20. Modification of a Scanning Tunneling Microscope for Measurement of Ballistic Electron Emission Microscopy

    NASA Astrophysics Data System (ADS)

    Hsieh, Satcher; Hong, Jeongmin; Bokor, Jeffrey

    2014-03-01

    Magnetic memory and logic devices show great promise for integration with, and even replacement of, conventional complementary metal-oxide-semiconductor (CMOS) architectures. In order to characterize materials and deposition techniques for these devices, ballistic electron emission microscopy (BEEM) is used. BEEM is a spatially resolved metrological tool most commonly used for subsurface interface structures at the nanometer scale. We modify a scanning tunneling microscope (STM) to perform BEEM measurement via design and fabrication of a novel sample stage. Furthermore, we design and fabricate an external magnetic field source that encapsulates the sample stage, setting the foundation for future measurement of ballistic electron magnetic microscopy (BEMM). Instrumentation of the device and characterization of a sample with an ohmic interface, Ni-Si, are implemented and discussed. With support from National Science Foundation Award ECCS-0939514.

  1. High-stability cryogenic scanning tunneling microscope based on a closed-cycle cryostat

    SciTech Connect

    Hackley, Jason D.; Kislitsyn, Dmitry A.; Beaman, Daniel K.; Nazin, George V.; Ulrich, Stefan

    2014-10-15

    We report on the design and operation of a cryogenic ultra-high vacuum (UHV) scanning tunneling microscope (STM) coupled to a closed-cycle cryostat (CCC). The STM is thermally linked to the CCC through helium exchange gas confined inside a volume enclosed by highly flexible rubber bellows. The STM is thus mechanically decoupled from the CCC, which results in a significant reduction of the mechanical noise transferred from the CCC to the STM. Noise analysis of the tunneling current shows current fluctuations up to 4% of the total current, which translates into tip-sample distance variations of up to 1.5 picometers. This noise level is sufficiently low for atomic-resolution imaging of a wide variety of surfaces. To demonstrate this, atomic-resolution images of Au(111) and NaCl(100)/Au(111) surfaces, as well as of carbon nanotubes deposited on Au(111), were obtained. Thermal drift analysis showed that under optimized conditions, the lateral stability of the STM scanner can be as low as 0.18 Å/h. Scanning Tunneling Spectroscopy measurements based on the lock-in technique were also carried out, and showed no detectable presence of noise from the closed-cycle cryostat. Using this cooling approach, temperatures as low as 16 K at the STM scanner have been achieved, with the complete cool-down of the system typically taking up to 12 h. These results demonstrate that the constructed CCC-coupled STM is a highly stable instrument capable of highly detailed spectroscopic investigations of materials and surfaces at the atomic scale.

  2. Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope

    SciTech Connect

    Hagedorn, Till; Ouali, Mehdi El; Paul, William; Oliver, David; Miyahara, Yoichi; Gruetter, Peter

    2011-11-15

    A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p {<=}10{sup -10} mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission.

  3. Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope.

    PubMed

    Hagedorn, Till; El Ouali, Mehdi; Paul, William; Oliver, David; Miyahara, Yoichi; Grütter, Peter

    2011-11-01

    A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p ≤10(-10) mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission.

  4. Modeling of Electronic Transport in Scanning Tunneling Microscope Tip-Carbon Nanotube Systems

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Kwak, Dochan (Technical Monitor)

    2000-01-01

    A model is proposed for two observed current-voltage (I-V) patterns in a recent experiment with a scanning tunneling microscope tip and a carbon nanotube. We claim that there are two mechanical contact modes for a tip (metal) -nanotube (semiconductor) junction (1) with or (2) without a tiny vacuum gap (0.1 - 0.2 nm). With the tip grounded, the tunneling case in (1) would produce large dI/dV with V > 0, small dI/dV with V < 0, and I = 0 near V = 0 for an either n- or p-nanotube; the Schottky mechanism in (2) would result in I does not equal 0 only with V < 0 for an n-nanotube, and the bias polarities would be reversed for a p-nanotube. The two observed I-V patterns are thus entirely explained by a tip-nanotube contact of the two types, where the nanotube must be n-type.

  5. Plasmon-induced fluorescence and electroluminescence from porphine molecules on GaAs(110) in a scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Mühlenberend, Svenja; Schneider, Natalia L.; Gruyters, Markus; Berndt, Richard

    2012-11-01

    Surface plasmon polaritons of the tip of a scanning tunneling microscope are used to induce fluorescence from (5,10,15,20)-tetraphenyl-21 H,23 H-porphine molecules on GaAs(110) surfaces at very low coverages. Fluorescence spectra exhibiting vibrationally resolved Q-band transitions show that the luminescence is of molecular origin. The emission is not directly induced by the tunneling current. Rather, radiationless energy transfer from plasmon modes of the tip leads to molecular excitation.

  6. Properties of Single Molecules: Manipulation, Dissociation and Synthesis with the Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Braun, Kai-Felix; Hla, Saw-Wai

    The fascinating advances in the manipulation of single atoms and molecules with the scanning tunneling microscope tip allow scientists to build atomic scale structures and to probe chemical and physical properties of matters at an atomic level. Due to these advances, the basic steps of a catalyzed chemical reaction such as dissociation, diffusion, adsorption, re-adsorption and bond formation processes can be performed by using the STM-tip. Here a short review of these steps and the techniques involved is presented. The lateral manipulation is used for the controlled positioning of atoms/molecules whereby only the tip- atom/molecule forces are employed. By measuring the tip-height signal during the manipulation, different modes of motion of the adparticle can be distinguished. Lower corrugated surfaces exhibit more complex motions than higher corrugated surfaces where the adparticle movement is confined to one dimension. Molecules have more degrees of freedom which allow a rotational motion or change in configuration. Even internal degrees of freedom can be detected and manipulated. The vertical manipulation not only allows the pick-up of adparticles and the subsequent transfer back to the surface, but also the manipulation of fragments of larger molecules. Effects due to the tunneling curent can be used for a controlled dissociation of chemical bonds as well as for the formation of new bonds. The combination of these manipulation techniques can induce chemical reactions at a single molecule level and construct new molecules. These achievements in STM manipulation of molecules open up new opportunities in nanochemistry and nanochemical technology. In this article, various STM manipulation techniques used for the single molecule reaction process are reviewed, and their impact on the future of nanoscience and nanotechnology is discussed.

  7. Nonlinearity, resonance, charging, and motion at the atomic scale studied with scanning tunneling microscopes

    NASA Astrophysics Data System (ADS)

    Tu, Xiuwen

    2008-10-01

    Several novel phenomena at the single-atom and single-molecule level occurring on the surfaces of single crystals were studied with home-built low temperature scanning tunneling microscopes. The results revealed intriguing properties of single atoms and single molecules, including nonlinearity, resonance, charging, and motion. First, negative differential resistance (NDR) was observed in the dI/dV spectra for single copper-phthalocyanine (CuPc) molecules adsorbed on one- and two-layer sodium bromide (NaBr), but not for single CuPc molecules adsorbed on three-layer NaBr, all grown on a NiAl(110) surface. This transition from NDR to the absence of NDR was explained as the result of competing effects in the double-barrier tunnel junction (DBTJ) and was reproduced in a calculation based on a resonant-tunneling model. Second, the nonlinearity of the STM junction due to a single manganese (Mn) atom or MnCO molecule adsorbed on a NiAl(110) surface was used to rectify microwave irradiation. The resulting rectification current was shown to be sensitive to the spin-splitting of the electronic states of the Mn atom and to the vibrations of the MnCO molecule. Next, the ordering of cesium (Cs) atoms adsorbed on a Au(111) surface and a NiAl(110) surface was imaged in real space. Because of charge transfer to the substrates, Cs adatoms were positively charged on both surfaces. Even at 12 K, Cs adatoms were able to move and adjust according to coverage. On Au(111), the Cs first layer had a quasi-hexagonal lattice and islands of the second Cs layer did not appear until the first was completed. On NiAl(110), a locally disordered Cs first layer was observed before a locally ordered layer appeared at higher coverages. The cation-pi interactions were then studied at the single molecular level. We were able to form cation-pi complexes such as Cs···DSB, Cs···DSB···Cs, Rb···DSB, and Rb···ZnEtiol controllably by manipulation with the STM tip. We could also separate these

  8. Fabrication and investigation of nanostructures on transition metal dichalcogenide surfaces using a scanning tunneling microscope.

    PubMed

    Park, J B; Jaeckel, B; Parkinson, B A

    2006-06-01

    Nanometer-scale holes have been fabricated on the surfaces of the semiconducting transition metal dichalcogenides (TMDCs) molybdenum ditelluride (MoTe2) and molybdenum disulfide (MoS2) by applying voltage pulses from the tip of a scanning tunneling microscope (STM) operating in ultrahigh vacuum (UHV). It was found that the tip geometry (tip shape and sharpness) influences the formation and structure of the atomic-scale nanostructures. Threshold voltage ranges for the surface modification of MoTe2 (3.0 +/- 0.3 V) and MoS2 (3.4 +/- 0.3 V) were determined. Negative sample voltage pulses applied to a p-type MoTe2 surface produced much larger and deeper nanometer-scale holes when compared with those produced by positive voltage pulses. The existence of threshold voltages and the pulse polarity dependence of nanostructure fabrication suggests that an electric field evaporation mechanism is applicable. Support for this mechanism was obtained by nanostructuring metallic TMDC NbSe2, where both the produced features and the threshold voltages (3.0 +/- 0.3 V) were similar for both positive and negative voltage pulses. PMID:16732661

  9. Influence of a dielectric layer on photon emission induced by a scanning tunneling microscope.

    PubMed

    Tao, X; Dong, Z C; Yang, J L; Luo, Y; Hou, J G; Aizpurua, J

    2009-02-28

    We investigate theoretically the influence of a dielectric layer on light emission induced by a scanning tunneling microscope through a combined approach of classical electrodynamics and first-principles calculations. The modification of the junction geometry upon the insertion of a dielectric layer is treated first by using the density functional theory to calculate the effective potential along the surface normal and then by solving a one-dimensional Schrodinger equation to obtain the exact distance between the tip and the substrate for a given current and bias voltage. The modified external field with the inclusion of a dielectric layer is evaluated by using the Fresnel formula. The local-field enhancement factor and radiated power are calculated by the boundary element method for two typical systems, W-tip/C(60)/Au(111) and W-tip/Al(2)O(3)/NiAl(110). The calculated results indicate that the insertion of a dielectric layer tends to reduce the light emission intensity considerably but hardly changes the spectral profile with no substantial peak shifts with respect to the layer-free situation, in agreement with experimental observations. The suppression of the radiated power is mainly due to the increase in the tip-metal separation and the resultant reduction in the electromagnetic coupling between the tip and metal substrate.

  10. A New Scanning Tunneling Microscope Reactor Used for High Pressure and High Temperature Catalysis Studies

    SciTech Connect

    Tao, Feng; Tang, David C.; Salmeron, Miquel; Somorjai, Gabor A.

    2008-05-12

    We present the design and performance of a home-built high-pressure and high-temperature reactor equipped with a high-resolution scanning tunneling microscope (STM) for catalytic studies. In this design, the STM body, sample, and tip are placed in a small high pressure reactor ({approx}19 cm{sup 3}) located within an ultrahigh vacuum (UHV) chamber. A sealable port on the wall of the reactor separates the high pressure environment in the reactor from the vacuum environment of the STM chamber and permits sample transfer and tip change in UHV. A combination of a sample transfer arm, wobble stick, and sample load-lock system allows fast transfer of samples and tips between the preparation chamber, high pressure reactor, and ambient environment. This STM reactor can work as a batch or flowing reactor at a pressure range of 10{sup -13} to several bars and a temperature range of 300-700 K. Experiments performed on two samples both in vacuum and in high pressure conditions demonstrate the capability of in situ investigations of heterogeneous catalysis and surface chemistry at atomic resolution at a wide pressure range from UHV to a pressure higher than 1 atm.

  11. Compact low temperature scanning tunneling microscope with in-situ sample preparation capability

    SciTech Connect

    Kim, Jungdae; Nam, Hyoungdo; Schroeder, Allan; Shih, Chih-Kang; Qin, Shengyong; Kim, Sang-ui; Eom, Daejin

    2015-09-15

    We report on the design of a compact low temperature scanning tunneling microscope (STM) having in-situ sample preparation capability. The in-situ sample preparation chamber was designed to be compact allowing quick transfer of samples to the STM stage, which is ideal for preparing temperature sensitive samples such as ultra-thin metal films on semiconductor substrates. Conventional spring suspensions on the STM head often cause mechanical issues. To address this problem, we developed a simple vibration damper consisting of welded metal bellows and rubber pads. In addition, we developed a novel technique to ensure an ultra-high-vacuum (UHV) seal between the copper and stainless steel, which provides excellent reliability for cryostats operating in UHV. The performance of the STM was tested from 2 K to 77 K by using epitaxial thin Pb films on Si. Very high mechanical stability was achieved with clear atomic resolution even when using cryostats operating at 77 K. At 2 K, a clean superconducting gap was observed, and the spectrum was easily fit using the BCS density of states with negligible broadening.

  12. Electrical Conductivity of Organic and Inorganic Nanowires Measured by Multi-probe Scanning Tunneling Microscopes

    NASA Astrophysics Data System (ADS)

    Aono, Masakazu

    2006-03-01

    Since 1998 [1], the authors and co-workers have developed multi-probe scanning tunneling microscopes (MPSTMs), in which two, three or four probes are operated independently. All probes of the MPSTMs can observe STM images independently, but the main role of the multiple probes is to be used as nanoscale electrodes that can contact any points selected in an observed STM image. It is therefore possible to measure electrical conductivity at the nanoscale through the multiple probes. By using MPSTMs and related methods, we measured the electrical conductivity of organic and inorganic nanowires, i.e., single-wall carbon nanotubes (SWCNTs), erbium disilicide (ErSi2) metallic nanowires, and single polydiacetylene (PDA) molecular wires. For a SWCNT and an ErSi2 nanowire, ballistic conduction was observed at lengths less than about 500 and 20 nm, respectively, at room temperature. For a PDA molecular wire, polaron formation due to charge injection caused by applying a voltage to an STM tip placed close to the PDA molecular wire was observed, and when the voltage exceeded a critical value, the PDA molecular wire changed into a metallic state. [1] M. Aono, C.-S. Jiang, T. Nakayama, T. Okuda, S. Qiao, M. Sakurai, C. Thirstrup, Z.-H. Wu: Oyo Buturi (Applied Physics) 67, 1361 (1998) (in Japanese); A brief English abstract is available on INSPEC.

  13. Compact low temperature scanning tunneling microscope with in-situ sample preparation capability

    NASA Astrophysics Data System (ADS)

    Kim, Jungdae; Nam, Hyoungdo; Qin, Shengyong; Kim, Sang-ui; Schroeder, Allan; Eom, Daejin; Shih, Chih-Kang

    2015-09-01

    We report on the design of a compact low temperature scanning tunneling microscope (STM) having in-situ sample preparation capability. The in-situ sample preparation chamber was designed to be compact allowing quick transfer of samples to the STM stage, which is ideal for preparing temperature sensitive samples such as ultra-thin metal films on semiconductor substrates. Conventional spring suspensions on the STM head often cause mechanical issues. To address this problem, we developed a simple vibration damper consisting of welded metal bellows and rubber pads. In addition, we developed a novel technique to ensure an ultra-high-vacuum (UHV) seal between the copper and stainless steel, which provides excellent reliability for cryostats operating in UHV. The performance of the STM was tested from 2 K to 77 K by using epitaxial thin Pb films on Si. Very high mechanical stability was achieved with clear atomic resolution even when using cryostats operating at 77 K. At 2 K, a clean superconducting gap was observed, and the spectrum was easily fit using the BCS density of states with negligible broadening.

  14. A 30 mK, 13.5 T scanning tunneling microscope with two independent tips

    SciTech Connect

    Roychowdhury, Anita; Gubrud, M. A.; Dana, R.; Dreyer, M.; Anderson, J. R.; Lobb, C. J.; Wellstood, F. C.

    2014-04-15

    We describe the design, construction, and performance of an ultra-low temperature, high-field scanning tunneling microscope (STM) with two independent tips. The STM is mounted on a dilution refrigerator and operates at a base temperature of 30 mK with magnetic fields of up to 13.5 T. We focus on the design of the two-tip STM head, as well as the sample transfer mechanism, which allows in situ transfer from an ultra high vacuum preparation chamber while the STM is at 1.5 K. Other design details such as the vibration isolation and rf-filtered wiring are also described. Their effectiveness is demonstrated via spectral current noise characteristics and the root mean square roughness of atomic resolution images. The high-field capability is shown by the magnetic field dependence of the superconducting gap of Cu{sub x}Bi{sub 2}Se{sub 3}. Finally, we present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 μeV.

  15. Compact low temperature scanning tunneling microscope with in-situ sample preparation capability.

    PubMed

    Kim, Jungdae; Nam, Hyoungdo; Qin, Shengyong; Kim, Sang-ui; Schroeder, Allan; Eom, Daejin; Shih, Chih-Kang

    2015-09-01

    We report on the design of a compact low temperature scanning tunneling microscope (STM) having in-situ sample preparation capability. The in-situ sample preparation chamber was designed to be compact allowing quick transfer of samples to the STM stage, which is ideal for preparing temperature sensitive samples such as ultra-thin metal films on semiconductor substrates. Conventional spring suspensions on the STM head often cause mechanical issues. To address this problem, we developed a simple vibration damper consisting of welded metal bellows and rubber pads. In addition, we developed a novel technique to ensure an ultra-high-vacuum (UHV) seal between the copper and stainless steel, which provides excellent reliability for cryostats operating in UHV. The performance of the STM was tested from 2 K to 77 K by using epitaxial thin Pb films on Si. Very high mechanical stability was achieved with clear atomic resolution even when using cryostats operating at 77 K. At 2 K, a clean superconducting gap was observed, and the spectrum was easily fit using the BCS density of states with negligible broadening.

  16. Design and properties of a cryogenic dip-stick scanning tunneling microscope with capacitive coarse approach control.

    PubMed

    Schlegel, R; Hänke, T; Baumann, D; Kaiser, M; Nag, P K; Voigtländer, R; Lindackers, D; Büchner, B; Hess, C

    2014-01-01

    We present the design, setup, and operation of a new dip-stick scanning tunneling microscope. Its special design allows measurements in the temperature range from 4.7 K up to room temperature, where cryogenic vacuum conditions are maintained during the measurement. The system fits into every (4)He vessel with a bore of 50 mm, e.g., a transport dewar or a magnet bath cryostat. The microscope is equipped with a cleaving mechanism for cleaving single crystals in the whole temperature range and under cryogenic vacuum conditions. For the tip approach, a capacitive automated coarse approach is implemented. We present test measurements on the charge density wave system 2H-NbSe2 and the superconductor LiFeAs which demonstrate scanning tunneling microscopy and spectroscopy data acquisition with high stability, high spatial resolution at variable temperatures and in high magnetic fields.

  17. High vacuum tip-enhanced Raman spectroscope based on a scanning tunneling microscope.

    PubMed

    Fang, Yurui; Zhang, Zhenglong; Sun, Mengtao

    2016-03-01

    In this paper, we present the construction of a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) system that allows in situ sample preparation and measurement. A detailed description of the prototype instrument is presented with experimental validation of its use and novel ex situ experimental results using the HV-TERS system. The HV-TERS system includes three chambers held under a 10(-7) Pa vacuum. The three chambers are an analysis chamber, a sample preparation chamber, and a fast loading chamber. The analysis chamber is the core chamber and contains a scanning tunneling microscope (STM) and a Raman detector coupled with a 50 × 0.5 numerical aperture objective. The sample preparation chamber is used to produce single-crystalline metal and sub-monolayer molecular films by molecular beam epitaxy. The fast loading chamber allows ex situ preparation of samples for HV-TERS analysis. Atomic resolution can be achieved by the STM on highly ordered pyrolytic graphite. We demonstrate the measurement of localized temperature using the Stokes and anti-Stokes TERS signals from a monolayer of 1,2-benzenedithiol on a gold film using a gold tip. Additionally, plasmonic catalysis can be monitored label-free at the nanoscale using our device. Moreover, the HV-TERS experiments show simultaneously activated infrared and Raman vibrational modes, Fermi resonance, and some other non-linear effects that are not observed in atmospheric TERS experiments. The high spatial and spectral resolution and pure environment of high vacuum are beneficial for basic surface studies. PMID:27036755

  18. Development of Near-Field Microwave Microscope with the Functionality of Scanning Tunneling Spectroscopy

    NASA Astrophysics Data System (ADS)

    Machida, Tadashi; Gaifullin, Marat B.; Ooi, Shuuich; Kato, Takuya; Sakata, Hideaki; Hirata, Kazuto

    2010-11-01

    We describe the details of an original near-field scanning microwave microscope, developed for simultaneous measurements of local density-of-states (LDOS) and local ohmic losses (LOL). Improving microwave detection systems, we have succeeded in distinguishing the LDOS and LOL even between two low resistance materials; gold and highly orientated pyrolitic graphite. The experimental data indicate that our microscope holds a capability to investigate both LDOS and LOL in nanoscale.

  19. Development of micro-four-point probe in a scanning tunneling microscope for in situ electrical transport measurement

    SciTech Connect

    Ge, Jian-Feng; Liu, Zhi-Long; Gao, Chun-Lei; Qian, Dong; Liu, Canhua E-mail: jfjia@sjtu.edu.cn; Jia, Jin-Feng E-mail: jfjia@sjtu.edu.cn

    2015-05-15

    Electrons at surface may behave differently from those in bulk of a material. Multi-functional tools are essential in comprehensive studies on a crystal surface. Here, we developed an in situ microscopic four-point probe (4PP) transport measurement system on the basis of a scanning tunneling microscope (STM). In particular, convenient replacement between STM tips and micro-4PPs enables systematic investigations of surface morphology, electronic structure, and electrical transport property of a same sample surface. Performances of the instrument are demonstrated with high-quality STM images, tunneling spectra, and low-noise electrical I-V characteristic curves of a single-layer FeSe film grown on a conductive SrTiO{sub 3} surface.

  20. Ultrafast scanning tunneling microscopy

    SciTech Connect

    Botkin, D.A. |

    1995-09-01

    I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

  1. Sample mounting and transfer for coupling an ultrahigh vacuum variable temperature beetle scanning tunneling microscope with conventional surface probes

    SciTech Connect

    Nafisi, Kourosh; Ranau, Werner; Hemminger, John C.

    2001-01-01

    We present a new ultrahigh vacuum (UHV) chamber for surface analysis and microscopy at controlled, variable temperatures. The new instrument allows surface analysis with Auger electron spectroscopy, low energy electron diffraction, quadrupole mass spectrometer, argon ion sputtering gun, and a variable temperature scanning tunneling microscope (VT-STM). In this system, we introduce a novel procedure for transferring a sample off a conventional UHV manipulator and onto a scanning tunneling microscope in the conventional ''beetle'' geometry, without disconnecting the heating or thermocouple wires. The microscope, a modified version of the Besocke beetle microscope, is mounted on a 2.75 in. outer diameter UHV flange and is directly attached to the base of the chamber. The sample is attached to a tripod sample holder that is held by the main manipulator. Under UHV conditions the tripod sample holder can be removed from the main manipulator and placed onto the STM. The VT-STM has the capability of acquiring images between the temperature range of 180--500 K. The performance of the chamber is demonstrated here by producing an ordered array of island vacancy defects on a Pt(111) surface and obtaining STM images of these defects.

  2. Scanning tunneling microscopic analysis of Cu(In,Ga)Se{sub 2} epitaxial layers

    SciTech Connect

    Mayer, Marie A.; Hebert, Damon; Rockett, Angus A.; Ruppalt, Laura B.; Lyding, Joseph

    2010-02-15

    Scanning tunneling microscopy (STM) measurements have been made on single-crystal epitaxial layers of CuInSe{sub 2} grown on GaAs substrates. Results were obtained for as-grown, air-exposed, and cleaned surfaces; in situ cleaved surfaces; surfaces sputtered and annealed in the STM system; and samples prepared by a light chemical etch. Conventional constant-current topographs, current-voltage curves, and current imaging tunneling spectroscopy (CITS) scans were obtained. Topographic images show that the surfaces appear rough on the atomic scale and often exhibit regular features consistent with a previously proposed surface ad-dimer reconstruction. CITS scans show a spatially varying energy gap consistent with band-edge fluctuations on a scale of a few atomic spacings. Energy variations were observed in both band edges. Although quantitative description of the magnitude of these fluctuations is difficult, the fluctuations on the atomic scale appear much larger than observed by methods such as photoluminescence, which average over larger volumes.

  3. A high-stability scanning tunneling microscope achieved by an isolated tiny scanner with low voltage imaging capability

    SciTech Connect

    Wang, Qi; Wang, Junting; Lu, Qingyou; Hou, Yubin

    2013-11-15

    We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d{sub 31} coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices.

  4. A high-stability scanning tunneling microscope achieved by an isolated tiny scanner with low voltage imaging capability

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Hou, Yubin; Wang, Junting; Lu, Qingyou

    2013-11-01

    We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d31 coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices.

  5. Low conductive support for thermal insulation of a sample holder of a variable temperature scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Hanzelka, Pavel; Vonka, Jakub; Musilova, Vera

    2013-08-01

    We have designed a supporting system to fix a sample holder of a scanning tunneling microscope in an UHV chamber at room temperature. The microscope will operate down to a temperature of 20 K. Low thermal conductance, high mechanical stiffness, and small dimensions are the main features of the supporting system. Three sets of four glass balls placed in vertices of a tetrahedron are used for thermal insulation based on small contact areas between the glass balls. We have analyzed the thermal conductivity of the contacts between the balls mutually and between a ball and a metallic plate while the results have been applied to the entire support. The calculation based on a simple model of the setup has been verified with some experimental measurements. In comparison with other feasible supporting structures, the designed support has the lowest thermal conductance.

  6. Low conductive support for thermal insulation of a sample holder of a variable temperature scanning tunneling microscope.

    PubMed

    Hanzelka, Pavel; Vonka, Jakub; Musilova, Vera

    2013-08-01

    We have designed a supporting system to fix a sample holder of a scanning tunneling microscope in an UHV chamber at room temperature. The microscope will operate down to a temperature of 20 K. Low thermal conductance, high mechanical stiffness, and small dimensions are the main features of the supporting system. Three sets of four glass balls placed in vertices of a tetrahedron are used for thermal insulation based on small contact areas between the glass balls. We have analyzed the thermal conductivity of the contacts between the balls mutually and between a ball and a metallic plate while the results have been applied to the entire support. The calculation based on a simple model of the setup has been verified with some experimental measurements. In comparison with other feasible supporting structures, the designed support has the lowest thermal conductance.

  7. The Scanning Optical Microscope.

    ERIC Educational Resources Information Center

    Sheppard, C. J. R.

    1978-01-01

    Describes the principle of the scanning optical microscope and explains its advantages over the conventional microscope in the improvement of resolution and contrast, as well as the possibility of producing a picture from optical harmonies generated within the specimen.

  8. Scattering of electrically excited surface plasmon polaritons by gold nanoparticles studied by optical interferometry with a scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Rogez, Benoît.; Comtet, Geneviève; Le Moal, Eric; Abidi, Wafa; Remita, Hynd; Dujardin, Gérald; Boer-Duchemin, Elizabeth

    2015-07-01

    We study the scattering of electrically excited surface plasmon polaritons (SPP) from individual nanostructures. The tunneling electrons from a scanning tunneling microscope (STM) are used to excite an out-going, circular SPP wave on a thin (50-nm) gold film on which isolated gold nanoparticles (NPs) have been deposited. Interaction of the excited SPPs with the NPs leads to both in-plane (SPP-to-SPP) and out-of-plane (SPP-to-photon) scattering. We use SPP leakage radiation microscopy to monitor the interference between the incident and in-plane scattered SPP waves in the image plane. By changing the location of the STM tip, the distance of the pointlike SPP source to the scatterers can be varied at will, which constitutes a key advantage over other existing techniques. As well, the out-of-plane scattered radiation interferes with the direct light emission from the STM tip in the back focal plane (Fourier plane). This confirms the mutual coherence of the light and SPP emission resulting from the inelastic tunneling of an electron in the STM junction. We use this effect to demonstrate that SPP-to-photon scattering at NPs is highly directional.

  9. Visualizing surface states of topological insulators using spectroscopic mapping with the scanning tunneling microscope

    NASA Astrophysics Data System (ADS)

    Roushan, Pedram

    2011-03-01

    In topological insulators, the spin texture of the surface states makes them distinct from conventional two-dimensional electron states, and leads to novel properties for these states. These surface states are expected to be immune to localization and to overcome barriers caused by material imperfections. We have used scanning tunneling microscopy and spectroscopy to study the topological surface states in Bi 0.9 Sb 0.1 , Sb, and Bi 2 Te 3 . By mapping the interference of the surface states scattering off random alloying disorder in Bi 0.9 Sb 0.1 , we have demonstrated that despite strong atomic scale disorder, backscattering between states of opposite momentum and opposite spin is absent, resulting from the spin texture. Furthermore, we have measured the transmission and reflection of topological surface states of Sb through atomic terraces. In contrast to Schottky surface states of noble metals, these surface states penetrate such barriers with high probability. To examine the possibility of disorder induced localization, we investigated the surface states of Bi 2 Te 3 in the presence of local defects. In the presence of magnetic dopants, we have observed an interference pattern throughout a broad range of energies, even in the region of linear dispersion near the Dirac point. We discuss the results of a statistical analysis of these patterns which can help to learn about the tendency toward localization for these surface states and how this trend is affected as the energy is tuned to the Dirac point. *Work was done in collaboration with J. Seo, H. Beidenkopf, L. Gorman, Y. S. Hor, C. Parker, D. Hsieh, and A. Richardella, M. Z. Hasan, R. Cava, and A. Yazdani. Supported by NSF-DMR, and MRSEC through PCCM. Infrastructure at Princeton Nanoscale Microscopy Laboratory are also supported by grants from DOE, and the W.M. Keck foundation.

  10. What is the orientation of the tip in a scanning tunneling microscope?

    NASA Astrophysics Data System (ADS)

    Mándi, Gábor; Teobaldi, Gilberto; Palotás, Krisztián

    2015-05-01

    The atomic structure and electronic properties of the tip apex can strongly affect the contrast of scanning tunneling microscopy (STM) images. This is a critical issue in STM imaging given the, to date unsolved, experimental limitations in precise control of the tip apex atomic structure. Definition of statistically robust procedures to indirectly obtain information on the tip apex structure is highly desirable as it would open up for more rigorous interpretation and comparison of STM images from different experiments. To this end, here we introduce a statistical correlation analysis method to obtain information on the local geometry and orientation of the tip used in STM experiments based on large scale simulations. The key quantity is the relative brightness correlation of constant-current topographs between experimental and simulated data. This correlation can be analyzed statistically for a large number of modeled tip orientations and geometries. Assuming a stable tip during the STM scans and based on the correlation distribution, it is possible to determine the tip orientations that are most likely present in an STM experiment, and exclude other orientations. This is especially important for substrates such as highly oriented pyrolytic graphite (HOPG) since its STM contrast is strongly tip dependent, which makes interpretation and comparison of STM images very challenging. We illustrate the applicability of our method considering the HOPG surface in combination with tungsten tip models of two different apex geometries and 18,144 different orientations. We calculate constant-current profiles along the < 1 1 bar 0 0 > direction of the HOPG(0 0 0 1) surface in the | V | ⩽ 1V bias voltage range, and compare them with experimental data. We find that a blunt tip model provides better correlation with the experiment for a wider range of tip orientations and bias voltages than a sharp tip model. Such a combination of experiments and large scale simulations opens up

  11. Si(100)-2 × 1-H dimer rows contrast inversion in low-temperature scanning tunneling microscope images

    NASA Astrophysics Data System (ADS)

    Yap, T. L.; Kawai, H.; Neucheva, O. A.; Wee, A. T. S.; Troadec, C.; Saeys, M.; Joachim, C.

    2015-02-01

    Detailed low temperature scanning tunneling microscope images of the Si(100)-2 × 1-H surface show a remarkable contrast inversion between filled- and empty-state images where the hydrogen dimer rows appear bright for filled-state images and dark for empty-state images. This contrast inversion originates from the change in the dominant surface states and their coupling to the tip apex and the bulk silicon channels as a function of the bias voltage: dimer Sisbnd Si bonding states dominate the filled-state images and valley states associated with Sisbnd Si anti-bonding states dominate the empty-state images. Care is required when constructing and interpreting the atomic structure of dangling-bond structures on the Si(100)-2 × 1-H surface.

  12. Manipulation of adsorbed atoms and creation of new structures on room-temperature surfaces with a scanning tunneling microscope.

    PubMed

    Whitman, L J; Stroscio, J A; Dragoset, R A; Celotta, R J

    1991-03-01

    A general method of manipulating adsorbed atoms and molecules on room-temperature surfaces with the use of a scanning tunneling microscope is described. By applying an appropriate voltage pulse between the sample and probe tip, adsorbed atoms can be induced to diffuse into the region beneath the tip. The field-induced diffusion occurs preferentially toward the tip during the voltage pulse because of the local potential energy gradient arising from the interaction of the adsorbate dipole moment with the electric field gradient at the surface. Depending upon the surface and pulse parameters, cesium (Cs) structures from one nanometer to a few tens of nanometers across have been created in this way on the (110) surfaces of gallium arsenide (GaAs) and indium antimonide (InSb), including structures that do not naturally occur.

  13. Combined low-temperature scanning tunneling/atomic force microscope for atomic resolution imaging and site-specific force spectroscopy

    SciTech Connect

    Schwarz, Udo; Albers, Boris J.; Liebmann, Marcus; Schwendemann, Todd C.; Baykara, Mehmet Z.; Heyde, Markus; Salmeron, Miquel; Altman, Eric I.; Schwarz, Udo D.

    2008-02-27

    The authors present the design and first results of a low-temperature, ultrahigh vacuum scanning probe microscope enabling atomic resolution imaging in both scanning tunneling microscopy (STM) and noncontact atomic force microscopy (NC-AFM) modes. A tuning-fork-based sensor provides flexibility in selecting probe tip materials, which can be either metallic or nonmetallic. When choosing a conducting tip and sample, simultaneous STM/NC-AFM data acquisition is possible. Noticeable characteristics that distinguish this setup from similar systems providing simultaneous STM/NC-AFM capabilities are its combination of relative compactness (on-top bath cryostat needs no pit), in situ exchange of tip and sample at low temperatures, short turnaround times, modest helium consumption, and unrestricted access from dedicated flanges. The latter permits not only the optical surveillance of the tip during approach but also the direct deposition of molecules or atoms on either tip or sample while they remain cold. Atomic corrugations as low as 1 pm could successfully be resolved. In addition, lateral drifts rates of below 15 pm/h allow long-term data acquisition series and the recording of site-specific spectroscopy maps. Results obtained on Cu(111) and graphite illustrate the microscope's performance.

  14. Design and calibration of a scanning tunneling microscope for large machined surfaces

    SciTech Connect

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

    1988-12-01

    During the last year the large sample STM has been designed, built and used for the observation of several different samples. Calibration of the scanner for prope dimensional interpretation of surface features has been a chief concern, as well as corrections for non-linear effects such as hysteresis during scans. Several procedures used in calibration and correction of piezoelectric scanners used in the laboratorys STMs are described.

  15. A new scanning tunneling microscope reactor used for high-pressure and high-temperature catalysis studies.

    PubMed

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

    2008-08-01

    We present the design and performance of a homebuilt high-pressure and high-temperature reactor equipped with a high-resolution scanning tunneling microscope (STM) for catalytic studies. In this design, the STM body, sample, and tip are placed in a small high pressure reactor ( approximately 19 cm(3)) located within an ultrahigh vacuum (UHV) chamber. A sealable port on the wall of the reactor separates the high pressure environment in the reactor from the vacuum environment of the STM chamber and permits sample transfer and tip change in UHV. A combination of a sample transfer arm, wobble stick, and sample load-lock system allows fast transfer of samples and tips between the preparation chamber, high pressure reactor, and ambient environment. This STM reactor can work as a batch or flowing reactor at a pressure range of 10(-13) to several bars and a temperature range of 300-700 K. Experiments performed on two samples both in vacuum and in high pressure conditions demonstrate the capability of in situ investigations of heterogeneous catalysis and surface chemistry at atomic resolution at a wide pressure range from UHV to a pressure higher than 1 atm.

  16. Scanning tunneling microscopic studies of laser-induced modifications of Si(001)-(2 x 1) surface

    SciTech Connect

    Yasui, Kosuke; Kanasaki, Jun'ichi

    2011-11-15

    Scanning tunneling microscopic studies of Si(001)-2 x 1 surfaces excited with 532-nm laser pulses of intensities below melting and ablation thresholds have revealed two different modes of structural modifications, strongly depending on the intensity of laser lights. The excitation below 100 mJ/cm{sup 2} causes bond rupture at individual dimer-sites leading to the formation of vacancies selectively on the outermost layer. The bond rupture, which shows a strongly site-sensitive rate, forms efficiently vacancy-strings elongated along the surface dimer-rows. Selective removal of surface dimers results in the exposure of flat and defect-less underlying layer as reported previously, which is resistive to the excitation at this range of intensity. At intensities above 100 mJ/cm{sup 2}, on the other hand, the excitation forms not only vacancies but also ad-dimers on terraces. The number density of ad-dimers is in proportion to the square of that for vacancies, indicating strongly that silicon atoms released by laser-induced bond rupture are associated with each other to form ad-dimers. The repeated irradiations at this range of intensities induce anisotropic growth of ad-dimer islands and of vacancy clusters on terrace regions, leading to multiply terraced structure. The primary processes of the structural modifications are discussed based on the quantitative analyses of the growth of vacancy and ad-dimer under excitation.

  17. Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies.

    PubMed

    Tao, Franklin Feng; Nguyen, Luan; Zhang, Shiran

    2013-03-01

    Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic scale during catalysis or under reaction conditions. In this HT-NAP-STM, the minimized reactor with a volume of reactant gases of ∼10 ml is thermally isolated from the STM room through a shielding dome installed between the reactor and STM room. An aperture on the dome was made to allow tip to approach to or retract from a catalyst surface in the reactor. This dome minimizes thermal diffusion from hot gas of the reactor to the STM room and thus remains STM head at a constant temperature near to room temperature, allowing observation of surface structures at atomic scale under reaction conditions or during catalysis with minimized thermal drift. The integrated quadrupole mass spectrometer can simultaneously measure products during visualization of surface structure of a catalyst. This synergy allows building an intrinsic correlation between surface structure and its catalytic performance. This correlation offers important insights for understanding of catalysis. Tests were done on graphite in ambient environment, Pt(111) in CO, graphene on Ru(0001) in UHV at high temperature and gaseous environment at high temperature. Atom-resolved surface structure of graphene on Ru(0001) at 500 K in a gaseous environment of 25 Torr was identified.

  18. Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies

    NASA Astrophysics Data System (ADS)

    Feng Tao, Franklin; Nguyen, Luan; Zhang, Shiran

    2013-03-01

    Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic scale during catalysis or under reaction conditions. In this HT-NAP-STM, the minimized reactor with a volume of reactant gases of ˜10 ml is thermally isolated from the STM room through a shielding dome installed between the reactor and STM room. An aperture on the dome was made to allow tip to approach to or retract from a catalyst surface in the reactor. This dome minimizes thermal diffusion from hot gas of the reactor to the STM room and thus remains STM head at a constant temperature near to room temperature, allowing observation of surface structures at atomic scale under reaction conditions or during catalysis with minimized thermal drift. The integrated quadrupole mass spectrometer can simultaneously measure products during visualization of surface structure of a catalyst. This synergy allows building an intrinsic correlation between surface structure and its catalytic performance. This correlation offers important insights for understanding of catalysis. Tests were done on graphite in ambient environment, Pt(111) in CO, graphene on Ru(0001) in UHV at high temperature and gaseous environment at high temperature. Atom-resolved surface structure of graphene on Ru(0001) at 500 K in a gaseous environment of 25 Torr was identified.

  19. Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies

    NASA Astrophysics Data System (ADS)

    Tao, Franklin Feng; Nguyen, Luan; Zhang, Shiran

    2013-03-01

    Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic scale during catalysis or under reaction conditions. In this HT-NAP-STM, the minimized reactor with a volume of reactant gases of ~10 ml is thermally isolated from the STM room through a shielding dome installed between the reactor and STM room. An aperture on the dome was made to allow tip to approach to or retract from a catalyst surface in the reactor. This dome minimizes thermal diffusion from hot gas of the reactor to the STM room and thus remains STM head at a constant temperature near to room temperature, allowing observation of surface structures at atomic scale under reaction conditions or during catalysis with minimized thermal drift. The integrated quadrupole mass spectrometer can simultaneously measure products during visualization of surface structure of a catalyst. This synergy allows building an intrinsic correlation between surface structure and its catalytic performance. This correlation offers important insights for understanding of catalysis. Tests were done on graphite in ambient environment, Pt(111) in CO, graphene on Ru(0001) in UHV at high temperature and gaseous environment at high temperature. Atom-resolved surface structure of graphene on Ru(0001) at 500 K in a gaseous environment of 25 Torr was identified.

  20. Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies.

    PubMed

    Tao, Franklin Feng; Nguyen, Luan; Zhang, Shiran

    2013-03-01

    Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic scale during catalysis or under reaction conditions. In this HT-NAP-STM, the minimized reactor with a volume of reactant gases of ∼10 ml is thermally isolated from the STM room through a shielding dome installed between the reactor and STM room. An aperture on the dome was made to allow tip to approach to or retract from a catalyst surface in the reactor. This dome minimizes thermal diffusion from hot gas of the reactor to the STM room and thus remains STM head at a constant temperature near to room temperature, allowing observation of surface structures at atomic scale under reaction conditions or during catalysis with minimized thermal drift. The integrated quadrupole mass spectrometer can simultaneously measure products during visualization of surface structure of a catalyst. This synergy allows building an intrinsic correlation between surface structure and its catalytic performance. This correlation offers important insights for understanding of catalysis. Tests were done on graphite in ambient environment, Pt(111) in CO, graphene on Ru(0001) in UHV at high temperature and gaseous environment at high temperature. Atom-resolved surface structure of graphene on Ru(0001) at 500 K in a gaseous environment of 25 Torr was identified. PMID:23556828

  1. Direct measurement instrument for lattice spacing on regular crystalline surfaces using a scanning tunneling microscope and laser interferometry

    NASA Astrophysics Data System (ADS)

    Rerkkumsup, Pongpun; Aketagawa, Masato; Takada, Koji; Watanabe, Tomonori; Sadakata, Shin

    2003-03-01

    An instrument for direct measurement of the lattice spacing on regular crystalline surfaces, which incorporates a scanning tunneling microscope (STM) and a phase modulation homodyne interferometer (PMHI), was developed. Our aim was to verify the applicability of the length measurement method in which the lattice spacing on the crystalline surface obtained with the STM is used as a fine scale and the optical interference fringe, i.e., wavelength λ, of the PMHI is used as a coarse scale. The instrument consists of a STM head with a YZ axes tip scanner, a precise X-axis sample stage with flexure springs, and the PMHI with a four-path differential configuration. Combining the movements of the YZ-axes tip scanner and the X-axis sample stage, the instrument can perform long atomic STM imaging of the crystalline surface along the X axis, which is also the fast scanning axis for eliminating thermal drift. The relative displacement of the X-axis sample stage between optical interference dark fringes (=null points) of the PMHI, which is λ/16 times the integer value in the design, can be measured with a resolution of 10 pm or less using the phase modulation technique. The lattice spacing on a highly oriented pyrolytic graphite (HOPG) crystalline surface was measured by comparing the number of atoms in the atomic STM image of 100 nm length with the optical fringes of the PMHI. The mean and expanded uncertainty (k=2) of the lattice spacing between α sites of the HOPG surface were 0.246 nm and 7 pm, respectively. The mean value was very close to that reported by Park and Quate [Sang-II Park and C. F. Quate, Appl. Phys. Lett. 48, 112 (1986)]. The experimental results also show the feasibility of realizing length measurement using the lattice spacing on the crystalline surface and the PMHI.

  2. Manipulation of subsurface carbon nanoparticles in Bi2Sr2CaCu2O8+δ using a scanning tunneling microscope

    DOE PAGES

    Stollenwerk, A. J.; Hurley, N.; Beck, B.; Spurgeon, K.; Kidd, T. E.; Gu, G.

    2015-03-19

    In this study, we present evidence that subsurface carbon nanoparticles in Bi₂Sr₂CaCu₂O8+δ can be manipulated with nanometer precision using a scanning tunneling microscope. High resolution images indicate that most of the carbon particles remain subsurface after transport observable as a local increase in height as the particle pushes up on the surface. Tunneling spectra in the vicinity of these protrusions exhibit semiconducting characteristics with a band gap of approximately 1.8 eV, indicating that the incorporation of carbon locally alters the electronic properties near the surface.

  3. Quantitative impedance characterization of sub-10 nm scale capacitors and tunnel junctions with an interferometric scanning microwave microscope.

    PubMed

    Wang, Fei; Clément, Nicolas; Ducatteau, Damien; Troadec, David; Tanbakuchi, Hassan; Legrand, Bernard; Dambrine, Gilles; Théron, Didier

    2014-10-10

    We present a method to characterize sub-10 nm capacitors and tunnel junctions by interferometric scanning microwave microscopy (iSMM) at 7.8 GHz. At such device scaling, the small water meniscus surrounding the iSMM tip should be reduced by proper tip tuning. Quantitative impedance characterization of attofarad range capacitors is achieved using an 'on-chip' calibration kit facing thousands of nanodevices. Nanoscale capacitors and tunnel barriers were detected through variations in the amplitude and phase of the reflected microwave signal, respectively. This study promises quantitative impedance characterization of a wide range of emerging functional nanoscale devices.

  4. Room temperature electron transport properties of single C{sub 60} studied using scanning tunneling microscope and reak junctions.

    SciTech Connect

    Cheng, R.; Carvell, J.; Fradin, F. Y.; Indiana Univ.-Purdue Univ. at Indianapolis

    2010-09-15

    We report the measurements of the electron transport of an individual C{sub 60} molecule through the combination of two experimental efforts. The nanometer-sized junctions were fabricated using electromigration combined with electron beam lithography and shadow effect evaporation. We performed the scanning tunneling microscopy/spectroscopy measurements of dispersed C{sub 60} molecules which were deposited on a highly ordered pyrolytic graphite substrate. The single electron tunneling through a single C{sub 60} molecule due to the Coulomb blockage effect is observed at room temperature.

  5. Scanning tunneling microscopy imaging of nanotubes

    SciTech Connect

    Antonenko, S. V. Malinovskaya, O. S.; Mal'tsev, S. N.

    2007-07-15

    Samples of carbon paper containing multiwalled carbon nanotube films are produced by current annealing. A scanning tunneling microscope is used to examine the structure of the modified carbon paper. X-, Y-, and V-shaped nanotubes are found.

  6. Forensic Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Keeley, R. H.

    1983-03-01

    The scanning electron microscope equipped with an x-ray spectrometer is a versatile instrument which has many uses in the investigation of crime and preparation of scientific evidence for the courts. Major applications include microscopy and analysis of very small fragments of paint, glass and other materials which may link an individual with a scene of crime, identification of firearms residues and examination of questioned documents. Although simultaneous observation and chemical analysis of the sample is the most important feature of the instrument, other modes of operation such as cathodoluminescence spectrometry, backscattered electron imaging and direct x-ray excitation are also exploited. Marks on two bullets or cartridge cases can be compared directly by sequential scanning with a single beam or electronic linkage of two instruments. Particles of primer residue deposited on the skin and clothing when a gun is fired can be collected on adhesive tape and identified by their morphology and elemental composition. It is also possible to differentiate between the primer residues of different types of ammunition. Bullets may be identified from the small fragments left behind as they pass through the body tissues. In the examination of questioned documents the scanning electron microscope is used to establish the order in which two intersecting ink lines were written and to detect traces of chemical markers added to the security inks on official documents.

  7. Graphene ripples as a realization of a two-dimensional Ising model: A scanning tunneling microscope study

    NASA Astrophysics Data System (ADS)

    Schoelz, J. K.; Xu, P.; Meunier, V.; Kumar, P.; Neek-Amal, M.; Thibado, P. M.; Peeters, F. M.

    2015-01-01

    Ripples in pristine freestanding graphene naturally orient themselves in an array that is alternately curved-up and curved-down; maintaining an average height of zero. Using scanning tunneling microscopy (STM) to apply a local force, the graphene sheet will reversibly rise and fall in height until the height reaches 60%-70% of its maximum at which point a sudden, permanent jump occurs. We successfully model the ripples as a spin-half Ising magnetic system, where the height of the graphene plays the role of the spin. The permanent jump in height, controlled by the tunneling current, is found to be equivalent to an antiferromagnetic-to-ferromagnetic phase transition. The thermal load underneath the STM tip alters the local tension and is identified as the responsible mechanism for the phase transition. Four universal critical exponents are measured from our STM data, and the model provides insight into the statistical role of graphene's unusual negative thermal expansion coefficient.

  8. Metrological scanning probe microscope

    NASA Astrophysics Data System (ADS)

    Dorozhovets, N.; Hausotte, T.; Manske, E.; Jäger, G.; Hofmann, N.

    2006-04-01

    Today's technological progress calls for metrologically accurate object measurement, positioning and scanning with nanometre precision and over large measuring ranges. In order to meet that requirement a nanopositioning and nanomeasuring machine (NPM machine) was developed at the Institute of Process Measurement and Sensor Technology of the Technische Universitaet Ilmenau. This device is capable of highly exact long-range positioning and measurement of objects with a resolution of less than 0.1 nm. Due to the structure of the machine many different probe systems can be installed, including scanning probe microscopes (SPMs). A few SPMs have outstanding metrological characteristics and many commercial microscopes only perform as image acquisition tools. Commercial SPMs use piezoelectric actuators in order to move either the sample or the probe. The position measurement sometimes results from the applied voltage to the piezoelectric actuators or from the strain gauge or capacitive displacement sensor data. This means that they suffer from hysteresis, creep, nonlinear characteristics and Abbe offsets. For an accurate measurement the position of the cantilever must be measured in addition to the torsion and bending. The best solution is a combined detection system with a single laser beam. This system has been realized with a special interferometer system, in which the measuring beam is focused on the cantilever backside using a lens. The reflected beam is split with a part being detected by a quadrant photo-diode and the other part being fed back into the interferometer for position measurement. The quadrant photo-diode is used to detect the cantilever torsion and bending.

  9. Probing the limits of Si:P δ-doped devices patterned by a scanning tunneling microscope in a field-emission mode

    SciTech Connect

    Rudolph, M.; Carr, S. M.; Ten Eyck, G.; Dominguez, J.; Carroll, M. S.; Bussmann, E.; Subramania, G.; Lilly, M. P.; Pluym, T.

    2014-10-20

    Recently, a single atom transistor was deterministically fabricated using phosphorus in Si by H-desorption lithography with a scanning tunneling microscope (STM). This milestone in precision, achieved by operating the STM in the conventional tunneling mode, typically utilizes slow (∼10{sup 2} nm{sup 2}/s) patterning speeds. By contrast, using the STM in a high-voltage (>10 V) field-emission mode, patterning speeds can be increased by orders of magnitude to ≳10{sup 4} nm{sup 2}/s. We show that the rapid patterning negligibly affects the functionality of relatively large micron-sized features, which act as contacting pads for these devices. For nanoscale structures, we show that the resulting electrical transport is consistent with the donor incorporation chemistry constraining the electrical dimensions to a scale of 10 nm even though the pattering spot size is 40 nm.

  10. Mirror buckling of freestanding graphene membranes induced by local heating due to a scanning tunneling microscope tip

    NASA Astrophysics Data System (ADS)

    Schoelz, J. K.; Neek Amal, M.; Xu, P.; Barber, S. D.; Ackerman, M. L.; Thibado, P. M.; Sadeghi, A.; Peeters, F. M.

    2014-03-01

    Scanning tunneling microscopy has been an invaluable tool in the study of graphene at the atomic scale. Several STM groups have managed to obtain atomic scale images of freestanding graphene membranes providing insight into the behavior of the stabilized ripple geometry. However, we found that the interaction between the STM tip and the freestanding graphene sample may induce additional effects. By varying the tunneling parameters, we can tune the position of the sample, in either a smooth or step like fashion. These phenomena were investigated by STM experiments, continuum elasticity theory and large scale molecular dynamics simulations. These results confirm that by increasing the tip bias, the electrostatic attraction between the tip and sample increases. When applied on a concave surface, this can result in mirror buckling which leads to a large scale movement of the sample. Interestingly, due in part to the negative coefficient of thermal expansion of graphene, buckling transitions can also be induced through local heating of the surface using the STM tip. Financial support by O.N.R. grant N00014-10-1-0181, N.S.F grant DMR-0855358, EU-Marie Curie IIF postdoc Fellowship/299855 (for M. N. A.), ESF-EuroGRAPHENE project CONGRAN, F.S.F (FWO-Vl), and Methusalem Foundation of the Flemish Government.

  11. Observation of deviation of electronic behaviour of indium tin oxide film at grain boundary using Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Kasiviswanathan, S.; Srinivas, V.; Kar, A. K.; Mathur, B. K.; Chopra, K. L.

    1997-03-01

    Scanning Tunneling Microscopy and Spectroscopy investigations have been carried out on electron beam deposited indium tin oxide films. The STM images reveal a rather smooth surface, which appears to have been formed due to the coalescence of islands with different shapes. The spectroscopic data, in general, exhibit characteristics typical of metal-insulator-semiconductor structures, with a heavily doped semiconductor. From the I- V curves, a band gap of ≈3.5 eV is obtained, which is very close to the bulk value. The I- V studies at some grain boundary interfaces suggest the presence of regions showing electronic characteristics, that differ significantly from what is observed on the rest of the film surface.

  12. Nanographenes as active components of single-molecule electronics and how a scanning tunneling microscope puts them to work.

    PubMed

    Müllen, Klaus; Rabe, Jürgen P

    2008-04-01

    Single-molecule electronics, that is, realizing novel electronic functionalities from single (or very few) molecules, holds promise for application in various technologies, including signal processing and sensing. Nanographenes, which are extended polycyclic aromatic hydrocarbons (PAHs), are highly attractive subjects for studies of single-molecule electronics because the electronic properties of their flat conjugated systems can be varied dramatically through synthetic modification of their sizes and topologies. Single nanographenes provide high tunneling currents when adsorbed flat onto conducting substrates, such as graphite. Because of their chemical inertness, nanographenes interact only weakly with these substrates, thereby preventing the need for special epitaxial structure matching. Instead, self-assembly at the interface between a conducting solid, such as the basal plane of graphite, and a nanographene solution generally leads to highly ordered monolayers. Scanning tunneling spectroscopy (STS) allows the current-voltage characteristics to be measured through a single molecule positioned between two electrodes; the key to the success of STS is the ability to position the scanning tunneling microscopy (STM) tip freely with respect to the molecule in all dimensions, that is, both parallel and perpendicular to the surface. In this Account, we report the properties of nanographenes having sizes ranging from 0.7 to 3.1 nm and exhibiting various symmetry, periphery, and substitution types. The size of the aromatic system and the nature of its perimeter are two essential features affecting its HOMO-LUMO gap and charge carrier mobility in the condensed phase. Moreover, the extended pi area of larger substituted PAHs improves the degree of self-ordering, another key requirement for high-performance electronic devices. Self-assembly at the interface between an organic solution and the basal plane of graphite allows deposition of single molecules within the well

  13. "We Actually Saw Atoms with Our Own Eyes": Conceptions and Convictions in Using the Scanning Tunneling Microscope in Junior High School

    ERIC Educational Resources Information Center

    Margel, Hannah; Eylon, Bat-Sheva; Scherz, Zahava

    2004-01-01

    The feasibility and the potential contribution of the scanning tunneling microscopy (STM) in junior high school (JHS) as an instructional tool for learning the particulate nature of matter is described. The use and power of new technologies can probably be demonstrated by the scanning tunneling microscopy (STM).

  14. Measurement of the quantum conductance of germanium by an electrochemical scanning tunneling microscope break junction based on a jump-to-contact mechanism.

    PubMed

    Xie, Xufen; Yan, Jiawei; Liang, Jinghong; Li, Jijun; Zhang, Meng; Mao, Bingwei

    2013-10-01

    We present quantum conductance measurements of germanium by means of an electrochemical scanning tunneling microscope (STM) break junction based on a jump-to-contact mechanism. Germanium nanowires between a platinum/iridium tip and different substrates were constructed to measure the quantum conductance. By applying appropriate potentials to the substrate and the tip, the process of heterogeneous contact and homogeneous breakage was realized. Typical conductance traces exhibit steps at 0.025 and 0.05 G0. The conductance histogram indicates that the conductance of germanium nanowires is located between 0.02 and 0.15 G0 in the low-conductance region and is free from the influence of substrate materials. However, the distribution of conductance plateaus is too discrete to display distinct peaks in the conductance histogram of the high-conductance region. PMID:23704043

  15. A 350 mK, 9 T scanning tunneling microscope for the study of superconducting thin films on insulating substrates and single crystals

    SciTech Connect

    Kamlapure, Anand; Saraswat, Garima; Ganguli, Somesh Chandra; Bagwe, Vivas; Raychaudhuri, Pratap; Pai, Subash P.

    2013-12-15

    We report the construction and performance of a low temperature, high field scanning tunneling microscope (STM) operating down to 350 mK and in magnetic fields up to 9 T, with thin film deposition and in situ single crystal cleaving capabilities. The main focus lies on the simple design of STM head and a sample holder design that allows us to get spectroscopic data on superconducting thin films grown in situ on insulating substrates. Other design details on sample transport, sample preparation chamber, and vibration isolation schemes are also described. We demonstrate the capability of our instrument through the atomic resolution imaging and spectroscopy on NbSe{sub 2} single crystal and spectroscopic maps obtained on homogeneously disordered NbN thin film.

  16. A scanning cavity microscope.

    PubMed

    Mader, Matthias; Reichel, Jakob; Hänsch, Theodor W; Hunger, David

    2015-01-01

    Imaging the optical properties of individual nanosystems beyond fluorescence can provide a wealth of information. However, the minute signals for absorption and dispersion are challenging to observe, and only specialized techniques requiring sophisticated noise rejection are available. Here we use signal enhancement in a high-finesse scanning optical microcavity to demonstrate ultra-sensitive imaging. Harnessing multiple interactions of probe light with a sample within an optical resonator, we achieve a 1,700-fold signal enhancement compared with diffraction-limited microscopy. We demonstrate quantitative imaging of the extinction cross-section of gold nanoparticles with a sensitivity less than 1 nm(2); we show a method to improve the spatial resolution potentially below the diffraction limit by using higher order cavity modes, and we present measurements of the birefringence and extinction contrast of gold nanorods. The demonstrated simultaneous enhancement of absorptive and dispersive signals promises intriguing potential for optical studies of nanomaterials, molecules and biological nanosystems. PMID:26105690

  17. 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

    SciTech Connect

    Tang, David Chi-Wai

    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).

  18. Line-scanning, stage scanning confocal microscope

    NASA Astrophysics Data System (ADS)

    Carucci, John A.; Stevenson, Mary; Gareau, Daniel

    2016-03-01

    We created a line-scanning, stage scanning confocal microscope as part of a new procedure: video assisted micrographic surgery (VAMS). The need for rapid pathological assessment of the tissue on the surface of skin excisions very large since there are 3.5 million new skin cancers diagnosed annually in the United States. The new design presented here is a confocal microscope without any scanning optics. Instead, a line is focused in space and the sample, which is flattened, is physically translated such that the line scans across its face in a direction perpendicular to the line its self. The line is 6mm long and the stage is capable of scanning 50 mm, hence the field of view is quite large. The theoretical diffraction-limited resolution is 0.7um lateral and 3.7um axial. However, in this preliminary report, we present initial results that are a factor of 5-7 poorer in resolution. The results are encouraging because they demonstrate that the linear array detector measures sufficient signal from fluorescently labeled tissue and also demonstrate the large field of view achievable with VAMS.

  19. Scanning Miniature Microscopes without Lenses

    NASA Technical Reports Server (NTRS)

    Wang, Yu

    2009-01-01

    The figure schematically depicts some alternative designs of proposed compact, lightweight optoelectronic microscopes that would contain no lenses and would generate magnified video images of specimens. Microscopes of this type were described previously in Miniature Microscope Without Lenses (NPO - 20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43 and Reflective Variants of Miniature Microscope Without Lenses (NPO 20610), NASA Tech Briefs, Vol. 26, No. 9 (September 1999), page 6a. To recapitulate: In the design and construction of a microscope of this type, the focusing optics of a conventional microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. Elimination of focusing optics reduces the size and weight of the instrument and eliminates the need for the time-consuming focusing operation. The microscopes described in the cited prior articles contained two-dimensional CCDs registered with two-dimensional arrays of microchannels and, as such, were designed to produce full two-dimensional images, without need for scanning. The microscopes of the present proposal would contain one-dimensional (line image) CCDs registered with linear arrays of microchannels. In the operation of such a microscope, one would scan a specimen along a line perpendicular to the array axis (in other words, one would scan in pushbroom fashion). One could then synthesize a full two-dimensional image of the specimen from the line-image data acquired at one-pixel increments of position along the scan. In one of the proposed microscopes, a beam of unpolarized light for illuminating the specimen would enter from the side. This light would be reflected down onto the specimen by a nonpolarizing beam splitter attached to the microchannels at their lower ends. A portion of the light incident on the specimen would be reflected upward, through the beam splitter and along the microchannels, to form an image on the CCD. If the

  20. Scanning tunneling spectroscopic evidence for a magnetic field-revealed microscopic order in the high-TC superconductor YBa2Cu3O7-δ

    NASA Astrophysics Data System (ADS)

    Beyer, A. D.; Grinolds, M. S.; Teague, M. L.; Yeh, N.-C.; Tajima, S.

    2009-03-01

    We present spatially resolved scanning tunneling spectroscopic measurements of YBa2Cu3O7-δ as a function of magnetic field and at T<microscopic order. Ref.: Beyer, et.al. [arxiv:0808.3016].

  1. Radio-frequency scanning tunnelling microscopy.

    PubMed

    Kemiktarak, U; Ndukum, T; Schwab, K C; Ekinci, K L

    2007-11-01

    The scanning tunnelling microscope (STM) relies on localized electron tunnelling between a sharp probe tip and a conducting sample to attain atomic-scale spatial resolution. In the 25-year period since its invention, the STM has helped uncover a wealth of phenomena in diverse physical systems--ranging from semiconductors to superconductors to atomic and molecular nanosystems. A severe limitation in scanning tunnelling microscopy is the low temporal resolution, originating from the diminished high-frequency response of the tunnel current readout circuitry. Here we overcome this limitation by measuring the reflection from a resonant inductor-capacitor circuit in which the tunnel junction is embedded, and demonstrate electronic bandwidths as high as 10 MHz. This approximately 100-fold bandwidth improvement on the state of the art translates into fast surface topography as well as delicate measurements in mesoscopic electronics and mechanics. Broadband noise measurements across the tunnel junction using this radio-frequency STM have allowed us to perform thermometry at the nanometre scale. Furthermore, we have detected high-frequency mechanical motion with a sensitivity approaching approximately 15 fm Hz(-1/2). This sensitivity is on par with the highest available from nanoscale optical and electrical displacement detection techniques, and the radio-frequency STM is expected to be capable of quantum-limited position measurements.

  2. Energy-gap spectroscopy of superconductors using a tunneling microscope

    NASA Technical Reports Server (NTRS)

    Le Duc, H. G.; Kaiser, W. J.; Stern, J. A.

    1987-01-01

    A unique scanning tunneling microscope (STM) system has been developed for spectroscopy of the superconducting energy gap. High-resolution control of tunnel current and voltage allows for measurement of superconducting properties at tunnel resistance levels 100-1000 greater than that achieved in prior work. The previously used STM methods for superconductor spectroscopy are compared to those developed for the work reported here. Superconducting energy-gap spectra are reported for three superconductors, Pb, PbBi, and NbN, over a range of tunnel resistance. The measured spectra are compared directly to theory.

  3. PREFACE: Time-resolved scanning tunnelling microscopy Time-resolved scanning tunnelling microscopy

    NASA Astrophysics Data System (ADS)

    Zandvliet, Harold J. W.; Lin, Nian

    2010-07-01

    Scanning tunnelling microscopy has revolutionized our ability to image, manipulate, and investigate solid surfaces on the length scale of individual atoms and molecules. The strength of this technique lies in its imaging capabilities, since for many scientists 'seeing is believing'. However, scanning tunnelling microscopy also suffers from a severe limitation, namely its poor time resolution. Recording a scanning tunnelling microscopy image typically requires a few tens of seconds for a conventional scanning tunnelling microscope to a fraction of a second for a specially designed fast scanning tunnelling microscope. Designing and building such a fast scanning tunnelling microscope is a formidable task in itself and therefore, only a limited number of these microscopes have been built [1]. There is, however, another alternative route to significantly enhance the time resolution of a scanning tunnelling microscope. In this alternative method, the tunnelling current is measured as a function of time with the feedback loop switched off. The time resolution is determined by the bandwidth of the IV converter rather than the cut-off frequency of the feedback electronics. Such an approach requires a stable microscope and goes, of course, at the expense of spatial information. In this issue, we have collected a set of papers that gives an impression of the current status of this rapidly emerging field [2]. One of the very first attempts to extract information from tunnel current fluctuations was reported by Tringides' group in the mid-1990s [3]. They showed that the collective diffusion coefficient can be extracted from the autocorrelation of the time-dependent tunnelling current fluctuations produced by atom motion in and out of the tunnelling junction. In general, current-time traces provide direct information on switching/conformation rates and distributions of residence times. In the case where these processes are thermally induced it is rather straightforward to map

  4. A novel digital scanning microscope

    NASA Astrophysics Data System (ADS)

    Lyu, Hong-Chou; Yu, Hsing-Cheng; Cheng, Kuen-Chiuan; Lee, Yuan-Chin; Ju, Jau-Jiu

    2011-06-01

    A novel digital scanning microscope (DSM) for observing cellular fluorescent micro-images is proposed and manufactured in this study. DSM applied in the biomedical field has been designed based on a concept of fast access time of an optical pick-up head (PUH) in optical disc devices; hence, DSM has been developed based on a blue-ray PUH module with a triaxial scanning actuator (TSA) system. High-resolution and high-speed scanning is effectively realized by TSA system instead of utilizing high-precision transpose stage mechanism. In consequent, a PUH module can work with a time-correlated single photon counting (TCSPC) module and serve as DSM for detecting fluorescent signals on samples.

  5. Scanning tunneling microscopy for ultracold atoms

    SciTech Connect

    Kollath, Corinna; Giamarchi, Thierry; Koehl, Michael

    2007-12-15

    We propose a versatile experimental probe for cold atomic gases analogous to the scanning tunneling microscope (STM) in condensed matter. This probe uses the coherent coupling of a single particle to the system. Depending on the measurement sequence, our probe allows us to obtain either the local density and spatial density correlations, with a resolution on the nanometer scale, or the single particle correlation function in real time. We discuss applications of this scheme to the various possible phases for a two dimensional Hubbard system of fermions in an optical lattice.

  6. The Scanning TMR Microscope for Biosensor Applications.

    PubMed

    Vyas, Kunal N; Love, David M; Ionescu, Adrian; Llandro, Justin; Kollu, Pratap; Mitrelias, Thanos; Holmes, Stuart; Barnes, Crispin H W

    2015-06-01

    We present a novel tunnel magnetoresistance (TMR) scanning microscope set-up capable of quantitatively imaging the magnetic stray field patterns of micron-sized elements in 3D. By incorporating an Anderson loop measurement circuit for impedance matching, we are able to detect magnetoresistance changes of as little as 0.006%/Oe. By 3D rastering a mounted TMR sensor over our magnetic barcodes, we are able to characterize the complex domain structures by displaying the real component, the amplitude and the phase of the sensor's impedance. The modular design, incorporating a TMR sensor with an optical microscope, renders this set-up a versatile platform for studying and imaging immobilised magnetic carriers and barcodes currently employed in biosensor platforms, magnetotactic bacteria and other complex magnetic domain structures of micron-sized entities. The quantitative nature of the instrument and its ability to produce vector maps of magnetic stray fields has the potential to provide significant advantages over other commonly used scanning magnetometry techniques. PMID:25849347

  7. The Scanning TMR Microscope for Biosensor Applications

    PubMed Central

    Vyas, Kunal N.; Love, David M.; Ionescu, Adrian; Llandro, Justin; Kollu, Pratap; Mitrelias, Thanos; Holmes, Stuart; Barnes, Crispin H. W.

    2015-01-01

    We present a novel tunnel magnetoresistance (TMR) scanning microscope set-up capable of quantitatively imaging the magnetic stray field patterns of micron-sized elements in 3D. By incorporating an Anderson loop measurement circuit for impedance matching, we are able to detect magnetoresistance changes of as little as 0.006%/Oe. By 3D rastering a mounted TMR sensor over our magnetic barcodes, we are able to characterise the complex domain structures by displaying the real component, the amplitude and the phase of the sensor’s impedance. The modular design, incorporating a TMR sensor with an optical microscope, renders this set-up a versatile platform for studying and imaging immobilised magnetic carriers and barcodes currently employed in biosensor platforms, magnetotactic bacteria and other complex magnetic domain structures of micron-sized entities. The quantitative nature of the instrument and its ability to produce vector maps of magnetic stray fields has the potential to provide significant advantages over other commonly used scanning magnetometry techniques. PMID:25849347

  8. Nanoscale Proximity Effect in the High-Temperature Superconductor Bi2Sr2CaCu2O8+δ Using a Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Parker, Colin V.; Pushp, Aakash; Pasupathy, Abhay N.; Gomes, Kenjiro K.; Wen, Jinsheng; Xu, Zhijun; Ono, Shimpei; Gu, Genda; Yazdani, Ali

    2010-03-01

    High-temperature cuprate superconductors exhibit extremely local nanoscale phenomena and strong sensitivity to doping. While other experiments have looked at nanoscale interfaces between layers of different dopings, we focus on the interplay between naturally inhomogeneous nanoscale regions. Using scanning tunneling microscopy to carefully track the same region of the sample as a function of temperature, we show that regions with weak superconductivity can persist to elevated temperatures if bordered by regions of strong superconductivity. This suggests that it may be possible to increase the maximum possible transition temperature by controlling the distribution of dopants.

  9. Nano-localized desorption and time-of-flight mass analysis using solely optical enhancement in the proximity of a scanning tunneling microscope tip

    NASA Astrophysics Data System (ADS)

    Ding, Yu; Micheletto, Ruggero; Okazaki, Satoshi; Otsuka, Koji

    2003-04-01

    The combination of scanning tunneling microscopy (STM) with time-of-flight mass system (TOF-MS) adds new information to STM imaging. In this study, an STM system has been combined with laser excitation and was used for desorption and ionization of surface molecules, without the use of any other external stimulus. Desorbed ions from confined areas were accelerated and detected by a TOF chamber. We demonstrate in this paper that the technique proposed enables desorption of superficial structures within a small area of approximately 5 nm diameter and simultaneous mass spectroscopy of the desorbed atoms.

  10. Scanning Tunneling Optical Resonance Microscopy Developed

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila G.; Raffaelle, Ryne P.; Lau, Janis E.; Jenkins, Phillip P.; Castro, Stephanie L.; Tin, Padetha; Wilt, David M.; Pal, Anna Maria; Fahey, Stephen D.

    2004-01-01

    The ability to determine the in situ optoelectronic properties of semiconductor materials has become especially important as the size of device architectures has decreased and the development of complex microsystems has increased. Scanning Tunneling Optical Resonance Microscopy, or STORM, can interrogate the optical bandgap as a function of its position within a semiconductor micro-structure. This technique uses a tunable solidstate titanium-sapphire laser whose output is "chopped" using a spatial light modulator and is coupled by a fiber-optic connector to a scanning tunneling microscope in order to illuminate the tip-sample junction. The photoenhanced portion of the tunneling current is spectroscopically measured using a lock-in technique. The capabilities of this technique were verified using semiconductor microstructure calibration standards that were grown by organometallic vapor-phase epitaxy. Bandgaps characterized by STORM measurements were found to be in good agreement with the bulk values determined by transmission spectroscopy and photoluminescence and with the theoretical values that were based on x-ray diffraction results.

  11. Sensing the quantum limit in scanning tunnelling spectroscopy

    PubMed Central

    Ast, Christian R.; Jäck, Berthold; Senkpiel, Jacob; Eltschka, Matthias; Etzkorn, Markus; Ankerhold, Joachim; Kern, Klaus

    2016-01-01

    The tunnelling current in scanning tunnelling spectroscopy (STS) is typically and often implicitly modelled by a continuous and homogeneous charge flow. If the charging energy of a single-charge quantum sufficiently exceeds the thermal energy, however, the granularity of the current becomes non-negligible. In this quantum limit, the capacitance of the tunnel junction mediates an interaction of the tunnelling electrons with the surrounding electromagnetic environment and becomes a source of noise itself, which cannot be neglected in STS. Using a scanning tunnelling microscope operating at 15 mK, we show that we operate in this quantum limit, which determines the ultimate energy resolution in STS. The P(E)-theory describes the probability for a tunnelling electron to exchange energy with the environment and can be regarded as the energy resolution function. We experimentally demonstrate this effect with a superconducting aluminium tip and a superconducting aluminium sample, where it is most pronounced. PMID:27708282

  12. Sensing the quantum limit in scanning tunnelling spectroscopy

    NASA Astrophysics Data System (ADS)

    Ast, Christian R.; Jäck, Berthold; Senkpiel, Jacob; Eltschka, Matthias; Etzkorn, Markus; Ankerhold, Joachim; Kern, Klaus

    2016-10-01

    The tunnelling current in scanning tunnelling spectroscopy (STS) is typically and often implicitly modelled by a continuous and homogeneous charge flow. If the charging energy of a single-charge quantum sufficiently exceeds the thermal energy, however, the granularity of the current becomes non-negligible. In this quantum limit, the capacitance of the tunnel junction mediates an interaction of the tunnelling electrons with the surrounding electromagnetic environment and becomes a source of noise itself, which cannot be neglected in STS. Using a scanning tunnelling microscope operating at 15 mK, we show that we operate in this quantum limit, which determines the ultimate energy resolution in STS. The P(E)-theory describes the probability for a tunnelling electron to exchange energy with the environment and can be regarded as the energy resolution function. We experimentally demonstrate this effect with a superconducting aluminium tip and a superconducting aluminium sample, where it is most pronounced.

  13. Experimental evidence for s-wave pairing symmetry in superconducting Cu(x)Bi2Se3 single crystals using a scanning tunneling microscope.

    PubMed

    Levy, Niv; Zhang, Tong; Ha, Jeonghoon; Sharifi, Fred; Talin, A Alec; Kuk, Young; Stroscio, Joseph A

    2013-03-15

    Topological superconductors represent a newly predicted phase of matter that is topologically distinct from conventional superconducting condensates of Cooper pairs. As a manifestation of their topological character, topological superconductors support solid-state realizations of Majorana fermions at their boundaries. The recently discovered superconductor Cu(x)Bi(2)Se(3) has been theoretically proposed as an odd-parity superconductor in the time-reversal-invariant topological superconductor class, and point-contact spectroscopy measurements have reported the observation of zero-bias conductance peaks corresponding to Majorana states in this material. Here we report scanning tunneling microscopy measurements of the superconducting energy gap in Cu(x)Bi(2)Se(3) as a function of spatial position and applied magnetic field. The tunneling spectrum shows that the density of states at the Fermi level is fully gapped without any in-gap states. The spectrum is well described by the Bardeen-Cooper-Schrieffer theory with a momentum independent order parameter, which suggests that Cu(x)Bi(2)Se(3) is a classical s-wave superconductor contrary to previous expectations and measurements.

  14. Probing the thermal decomposition behaviors of ultrathin HfO2 films by an in situ high temperature scanning tunneling microscope.

    PubMed

    Xue, Kun; Wang, Lei; An, Jin; Xu, Jianbin

    2011-05-13

    The thermal decomposition of ultrathin HfO(2) films (∼0.6-1.2 nm) on Si by ultrahigh vacuum annealing (25-800 °C) is investigated in situ in real time by scanning tunneling microscopy. Two distinct thickness-dependent decomposition behaviors are observed. When the HfO(2) thickness is ∼ 0.6 nm, no discernible morphological changes are found below ∼ 700 °C. Then an abrupt reaction occurs at 750 °C with crystalline hafnium silicide nanostructures formed instantaneously. However, when the thickness is about 1.2 nm, the decomposition proceeds gradually with the creation and growth of two-dimensional voids at 800 °C. The observed thickness-dependent behavior is closely related to the SiO desorption, which is believed to be the rate-limiting step of the decomposition process.

  15. Infrared emission from tunneling electrons: The end of the rainbow in scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Boyle, Michael G.; Mitra, J.; Dawson, P.

    2009-06-01

    Electromagnetic radiation originating with localized surface plasmons in the metal-tip/metal-sample nanocavity of a scanning tunneling microscope is demonstrated to extend to a wavelength λ of at least 1.7 μm. Progressive spectral extension beyond λ ˜1.0 μm occurs for increasing tip radius above ˜15 nm, reaching λ ˜1.7 μm for tip radius ˜100 nm; these observations are corroborated by use of a simple physical model that relates the discrete plasmon mode frequencies to the tip radius. This spectral extension opens up a new regime for scanning tunneling microscope-based optical spectroscopy.

  16. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen; Schultz, Peter G.; Wei, Tao

    2003-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  17. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen

    2001-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  18. A versatile high resolution scanning tunneling potentiometry implementation.

    PubMed

    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.

  19. Scanning tunneling and scanning transmission electron microscopy of biological membranes

    NASA Astrophysics Data System (ADS)

    Stemmer, A.; Reichelt, R.; Engel, A.; Rosenbusch, J. P.; Ringger, M.; Hidber, H. R.; Güntherodt, H. J.

    1987-03-01

    The feasibility of imaging porin membrane, which is a reconstituted biological membrane consisting of phospholipid and protein, was studied by scanning tunneling microscopy (STM). Due to detailed knowledge of its composition from biochemical and its three-dimensional (3D) structure from electron microscopical analysis, porin vesicles seem to be a suitable model specimen for exploring the application of STM in biology. Unstained vesicles adsorbed onto a thin amorphous carbon film supported by a finder grid were localized using a scanning transmission electron microscope (STEM) at low irradiation doses ( < 100 {e -}/{nm 2}). Suitable areas of the sample were then positioned in the STM by a light optical telescope. STM images taken under ambient pressure from empty amorphous carbon films exhibited corrugations in the range of ⩽ 1 nm, whereas steps having a height of 5 nm were reproducibly observed on grids with porin vesicles. Since this value is in good agreement with that obtained from air-dried metal shadowed vesicles, we interpret these steps as the edges of porin membranes.

  20. First results for custom-built low-temperature (4.2 K) scanning tunneling microscope/molecular beam epitaxy and pulsed laser epitaxy system designed for spin-polarized measurements

    NASA Astrophysics Data System (ADS)

    Foley, Andrew; Alam, Khan; Lin, Wenzhi; Wang, Kangkang; Chinchore, Abhijit; Corbett, Joseph; Savage, Alan; Chen, Tianjiao; Shi, Meng; Pak, Jeongihm; Smith, Arthur

    2014-03-01

    A custom low-temperature (4.2 K) scanning tunneling microscope system has been developed which is combined directly with a custom molecular beam epitaxy facility (and also including pulsed laser epitaxy) for the purpose of studying surface nanomagnetism of complex spintronic materials down to the atomic scale. For purposes of carrying out spin-polarized STM measurements, the microscope is built into a split-coil, 4.5 Tesla superconducting magnet system where the magnetic field can be applied normal to the sample surface; since, as a result, the microscope does not include eddy current damping, vibration isolation is achieved using a unique combination of two stages of pneumatic isolators along with an acoustical noise shield, in addition to the use of a highly stable as well as modular `Pan'-style STM design with a high Q factor. First 4.2 K results reveal, with clear atomic resolution, various reconstructions on wurtzite GaN c-plane surfaces grown by MBE, including the c(6x12) on N-polar GaN(0001). Details of the system design and functionality will be presented.

  1. Scanning Microscopes Using X Rays and Microchannels

    NASA Technical Reports Server (NTRS)

    Wang, Yu

    2003-01-01

    Scanning microscopes that would be based on microchannel filters and advanced electronic image sensors and that utilize x-ray illumination have been proposed. Because the finest resolution attainable in a microscope is determined by the wavelength of the illumination, the xray illumination in the proposed microscopes would make it possible, in principle, to achieve resolutions of the order of nanometers about a thousand times as fine as the resolution of a visible-light microscope. Heretofore, it has been necessary to use scanning electron microscopes to obtain such fine resolution. In comparison with scanning electron microscopes, the proposed microscopes would likely be smaller, less massive, and less expensive. Moreover, unlike in scanning electron microscopes, it would not be necessary to place specimens under vacuum. The proposed microscopes are closely related to the ones described in several prior NASA Tech Briefs articles; namely, Miniature Microscope Without Lenses (NPO-20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43; and Reflective Variants of Miniature Microscope Without Lenses (NPO-20610), NASA Tech Briefs, Vol. 26, No. 9 (September 2002) page 6a. In all of these microscopes, the basic principle of design and operation is the same: The focusing optics of a conventional visible-light microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. A microchannel plate containing parallel, microscopic-cross-section holes much longer than they are wide is placed between a specimen and an image sensor, which is typically the CCD. The microchannel plate must be made of a material that absorbs the illuminating radiation reflected or scattered from the specimen. The microchannels must be positioned and dimensioned so that each one is registered with a pixel on the image sensor. Because most of the radiation incident on the microchannel walls becomes absorbed, the radiation that reaches the

  2. Three-dimensional scanning confocal laser microscope

    DOEpatents

    Anderson, R. Rox; Webb, Robert H.; Rajadhyaksha, Milind

    1999-01-01

    A confocal microscope for generating an image of a sample includes a first scanning element for scanning a light beam along a first axis, and a second scanning element for scanning the light beam at a predetermined amplitude along a second axis perpendicular to the first axis. A third scanning element scans the light beam at a predetermined amplitude along a third axis perpendicular to an imaging plane defined by the first and second axes. The second and third scanning element are synchronized to scan at the same frequency. The second and third predetermined amplitudes are percentages of their maximum amplitudes. A selector determines the second and third predetermined amplitudes such that the sum of the percentages is equal to one-hundred percent.

  3. An interchangeable scanning Hall probe/scanning SQUID microscope

    SciTech Connect

    Tang, Chiu-Chun; Lin, Hui-Ting; Wu, Sing-Lin; Chen, Tse-Jun; Wang, M. J.; Ling, D. C.; Chi, C. C.; Chen, Jeng-Chung

    2014-08-15

    We have constructed a scanning probe microscope for magnetic imaging, which can function as a scanning Hall probe microscope (SHPM) and as a scanning SQUID microscope (SSM). The scanning scheme, applicable to SHPM and SSM, consists of a mechanical positioning (sub) micron-XY stage and a flexible direct contact to the sample without a feedback control system for the Z-axis. With the interchangeable capability of operating two distinct scanning modes, our microscope can incorporate the advantageous functionalities of the SHPM and SSM with large scan range up to millimeter, high spatial resolution (⩽4 μm), and high field sensitivity in a wide range of temperature (4.2 K-300 K) and magnetic field (10{sup −7} T-1 T). To demonstrate the capabilities of the system, we present magnetic images scanned with SHPM and SSM, including a RbFeB magnet and a nickel grid pattern at room temperature, surface magnetic domain structures of a La{sub 2/3}Ca{sub 1/3}MnO{sub 3} thin film at 77 K, and superconducting vortices in a striped niobium film at 4.2 K.

  4. An interchangeable scanning Hall probe/scanning SQUID microscope.

    PubMed

    Tang, Chiu-Chun; Lin, Hui-Ting; Wu, Sing-Lin; Chen, Tse-Jun; Wang, M J; Ling, D C; Chi, C C; Chen, Jeng-Chung

    2014-08-01

    We have constructed a scanning probe microscope for magnetic imaging, which can function as a scanning Hall probe microscope (SHPM) and as a scanning SQUID microscope (SSM). The scanning scheme, applicable to SHPM and SSM, consists of a mechanical positioning (sub) micron-XY stage and a flexible direct contact to the sample without a feedback control system for the Z-axis. With the interchangeable capability of operating two distinct scanning modes, our microscope can incorporate the advantageous functionalities of the SHPM and SSM with large scan range up to millimeter, high spatial resolution (⩽4 μm), and high field sensitivity in a wide range of temperature (4.2 K-300 K) and magnetic field (10(-7) T-1 T). To demonstrate the capabilities of the system, we present magnetic images scanned with SHPM and SSM, including a RbFeB magnet and a nickel grid pattern at room temperature, surface magnetic domain structures of a La(2/3)Ca(1/3)MnO3 thin film at 77 K, and superconducting vortices in a striped niobium film at 4.2 K. PMID:25173276

  5. An interchangeable scanning Hall probe/scanning SQUID microscope.

    PubMed

    Tang, Chiu-Chun; Lin, Hui-Ting; Wu, Sing-Lin; Chen, Tse-Jun; Wang, M J; Ling, D C; Chi, C C; Chen, Jeng-Chung

    2014-08-01

    We have constructed a scanning probe microscope for magnetic imaging, which can function as a scanning Hall probe microscope (SHPM) and as a scanning SQUID microscope (SSM). The scanning scheme, applicable to SHPM and SSM, consists of a mechanical positioning (sub) micron-XY stage and a flexible direct contact to the sample without a feedback control system for the Z-axis. With the interchangeable capability of operating two distinct scanning modes, our microscope can incorporate the advantageous functionalities of the SHPM and SSM with large scan range up to millimeter, high spatial resolution (⩽4 μm), and high field sensitivity in a wide range of temperature (4.2 K-300 K) and magnetic field (10(-7) T-1 T). To demonstrate the capabilities of the system, we present magnetic images scanned with SHPM and SSM, including a RbFeB magnet and a nickel grid pattern at room temperature, surface magnetic domain structures of a La(2/3)Ca(1/3)MnO3 thin film at 77 K, and superconducting vortices in a striped niobium film at 4.2 K.

  6. Excitation-scanning hyperspectral imaging microscope.

    PubMed

    Favreau, Peter F; Hernandez, Clarissa; Heaster, Tiffany; Alvarez, Diego F; Rich, Thomas C; Prabhat, Prashant; Leavesley, Silas J

    2014-04-01

    Hyperspectral imaging is a versatile tool that has recently been applied to a variety of biomedical applications, notably live-cell and whole-tissue signaling. Traditional hyperspectral imaging approaches filter the fluorescence emission over a broad wavelength range while exciting at a single band. However, these emission-scanning approaches have shown reduced sensitivity due to light attenuation from spectral filtering. Consequently, emission scanning has limited applicability for time-sensitive studies and photosensitive applications. In this work, we have developed an excitation-scanning hyperspectral imaging microscope that overcomes these limitations by providing high transmission with short acquisition times. This is achieved by filtering the fluorescence excitation rather than the emission. We tested the efficacy of the excitation-scanning microscope in a side-by-side comparison with emission scanning for detection of green fluorescent protein (GFP)-expressing endothelial cells in highly autofluorescent lung tissue. Excitation scanning provided higher signal-to-noise characteristics, as well as shorter acquisition times (300  ms/wavelength band with excitation scanning versus 3  s/wavelength band with emission scanning). Excitation scanning also provided higher delineation of nuclear and cell borders, and increased identification of GFP regions in highly autofluorescent tissue. These results demonstrate excitation scanning has utility in a wide range of time-dependent and photosensitive applications. PMID:24727909

  7. Excitation-scanning hyperspectral imaging microscope

    PubMed Central

    Favreau, Peter F.; Hernandez, Clarissa; Heaster, Tiffany; Alvarez, Diego F.; Rich, Thomas C.; Prabhat, Prashant; Leavesley, Silas J.

    2014-01-01

    Abstract. Hyperspectral imaging is a versatile tool that has recently been applied to a variety of biomedical applications, notably live-cell and whole-tissue signaling. Traditional hyperspectral imaging approaches filter the fluorescence emission over a broad wavelength range while exciting at a single band. However, these emission-scanning approaches have shown reduced sensitivity due to light attenuation from spectral filtering. Consequently, emission scanning has limited applicability for time-sensitive studies and photosensitive applications. In this work, we have developed an excitation-scanning hyperspectral imaging microscope that overcomes these limitations by providing high transmission with short acquisition times. This is achieved by filtering the fluorescence excitation rather than the emission. We tested the efficacy of the excitation-scanning microscope in a side-by-side comparison with emission scanning for detection of green fluorescent protein (GFP)-expressing endothelial cells in highly autofluorescent lung tissue. Excitation scanning provided higher signal-to-noise characteristics, as well as shorter acquisition times (300  ms/wavelength band with excitation scanning versus 3  s/wavelength band with emission scanning). Excitation scanning also provided higher delineation of nuclear and cell borders, and increased identification of GFP regions in highly autofluorescent tissue. These results demonstrate excitation scanning has utility in a wide range of time-dependent and photosensitive applications. PMID:24727909

  8. Scanning scene tunnel for city traversing.

    PubMed

    Zheng, Jiang Yu; Zhou, Yu; Milli, Panayiotis

    2006-01-01

    This paper proposes a visual representation named scene tunnel for capturing urban scenes along routes and visualizing them on the Internet. We scan scenes with multiple cameras or a fish-eye camera on a moving vehicle, which generates a real scene archive along streets that is more complete than previously proposed route panoramas. Using a translating spherical eye, properly set planes of scanning, and unique parallel-central projection, we explore the image acquisition of the scene tunnel from camera selection and alignment, slit calculation, scene scanning, to image integration. The scene tunnels cover high buildings, ground, and various viewing directions and have uniformed resolutions along the street. The sequentially organized scene tunnel benefits texture mapping onto the urban models. We analyze the shape characteristics in the scene tunnels for designing visualization algorithms. After combining this with a global panorama and forward image caps, the capped scene tunnels can provide continuous views directly for virtual or real navigation in a city. We render scene tunnel dynamically by view warping, fast transmission, and flexible interaction. The compact and continuous scene tunnel facilitates model construction, data streaming, and seamless route traversing on the Internet and mobile devices.

  9. Scanning scene tunnel for city traversing.

    PubMed

    Zheng, Jiang Yu; Zhou, Yu; Milli, Panayiotis

    2006-01-01

    This paper proposes a visual representation named scene tunnel for capturing urban scenes along routes and visualizing them on the Internet. We scan scenes with multiple cameras or a fish-eye camera on a moving vehicle, which generates a real scene archive along streets that is more complete than previously proposed route panoramas. Using a translating spherical eye, properly set planes of scanning, and unique parallel-central projection, we explore the image acquisition of the scene tunnel from camera selection and alignment, slit calculation, scene scanning, to image integration. The scene tunnels cover high buildings, ground, and various viewing directions and have uniformed resolutions along the street. The sequentially organized scene tunnel benefits texture mapping onto the urban models. We analyze the shape characteristics in the scene tunnels for designing visualization algorithms. After combining this with a global panorama and forward image caps, the capped scene tunnels can provide continuous views directly for virtual or real navigation in a city. We render scene tunnel dynamically by view warping, fast transmission, and flexible interaction. The compact and continuous scene tunnel facilitates model construction, data streaming, and seamless route traversing on the Internet and mobile devices. PMID:16509375

  10. Manipulative Scanning Tunneling Microscopy and Molecular Spintronics

    NASA Astrophysics Data System (ADS)

    DiLullo, Andrew R.

    theoretical and spectroscopic techniques. The measurements of magnetic interaction and spin-communication along a covalently bound chain of molecules can be extended with transport and spin-polarized measurements. Together the techniques and results presented here demonstrate novel physical phenomena at atomic and molecular scales, by utilizing the versatility of scanning tunneling microscopic techniques, with implications for both fundamental scientific principles and applications.

  11. A nanoscale gigahertz source realized with Josephson scanning tunneling microscopy

    SciTech Connect

    Jäck, Berthold Eltschka, Matthias; Assig, Maximilian; Etzkorn, Markus; Ast, Christian R.; Hardock, Andreas; Kern, Klaus

    2015-01-05

    Using the AC Josephson effect in the superconductor-vacuum-superconductor tunnel junction of a scanning tunneling microscope (STM), we demonstrate the generation of GHz radiation. With the macroscopic STM tip acting as a λ/4-monopole antenna, we first show that the atomic scale Josephson junction in the STM is sensitive to its frequency-dependent environmental impedance in the GHz regime. Further, enhancing Cooper pair tunneling via excitations of the tip eigenmodes, we are able to generate high-frequency radiation. We find that for vanadium junctions, the enhanced photon emission can be tuned from about 25 GHz to 200 GHz and that large photon flux in excess of 10{sup 20 }cm{sup −2} s{sup −1} is reached in the tunnel junction. These findings demonstrate that the atomic scale Josephson junction in an STM can be employed as a full spectroscopic tool for GHz frequencies on the atomic scale.

  12. Vertically aligned nanostructure scanning probe microscope tips

    DOEpatents

    Guillorn, Michael A.; Ilic, Bojan; Melechko, Anatoli V.; Merkulov, Vladimir I.; Lowndes, Douglas H.; Simpson, Michael L.

    2006-12-19

    Methods and apparatus are described for cantilever structures that include a vertically aligned nanostructure, especially vertically aligned carbon nanofiber scanning probe microscope tips. An apparatus includes a cantilever structure including a substrate including a cantilever body, that optionally includes a doped layer, and a vertically aligned nanostructure coupled to the cantilever body.

  13. Macroscopic model of scanning force microscope

    DOEpatents

    Guerra-Vela, Claudio; Zypman, Fredy R.

    2004-10-05

    A macroscopic version of the Scanning Force Microscope is described. It consists of a cantilever under the influence of external forces, which mimic the tip-sample interactions. The use of this piece of equipment is threefold. First, it serves as direct way to understand the parts and functions of the Scanning Force Microscope, and thus it is effectively used as an instructional tool. Second, due to its large size, it allows for simple measurements of applied forces and parameters that define the state of motion of the system. This information, in turn, serves to compare the interaction forces with the reconstructed ones, which cannot be done directly with the standard microscopic set up. Third, it provides a kinematics method to non-destructively measure elastic constants of materials, such as Young's and shear modules, with special application for brittle materials.

  14. Imaging of a molecular wheelbarrow by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Grill, Leonhard; Rieder, Karl-Heinz; Moresco, Francesca; Jimenez-Bueno, Gorka; Wang, Cheng; Rapenne, Gwénaël; Joachim, Christian

    2005-06-01

    We have studied the deposition and imaging of nanoscale molecular wheelbarrows. These molecules integrate—in analogy to macroscopic barrows—two wheels, legs and handles along a polyaromatic platform and were imaged on a clean Cu(1 0 0) surface with a scanning tunneling microscope at 7 K. The obtained images are in accordance with calculations and are dominated by the wheels. Several stable conformations of the wheelbarrow were found and identified by comparison with calculated images.

  15. Hardware for digitally controlled scanned probe microscopes

    NASA Astrophysics Data System (ADS)

    Clark, S. M.; Baselt, D. R.; Spence, C. F.; Youngquist, M. G.; Baldeschwieler, J. D.

    1992-10-01

    The design and implementation of a flexible and modular digital control and data acquisition system for scanned probe microscopes (SPMs) is presented. The measured performance of the system shows it to be capable of 14-bit data acquisition at a 100-kHz rate and a full 18-bit output resolution resulting in less than 0.02-Å rms position noise while maintaining a scan range in excess of 1 μm in both the X and Y dimensions. This level of performance achieves the goal of making the noise of the microscope control system an insignificant factor for most experiments. The adaptation of the system to various types of SPM experiments is discussed. Advances in audio electronics and digital signal processors have made the construction of such high performance systems possible at low cost.

  16. Scanning electron microscopic autoradiography of lung

    SciTech Connect

    Lauhala, K.E.; Sanders, C.L.; McDonald, K.E.

    1988-09-01

    Scanning electron microscopic (SEM) autoradiography of the lung is being used to determine the distribution of inhaled, alpha particle-emitting, plutonium dioxide particles. SEM autoradiography provides high visual impact views of alpha activity. Particles irradiating the bronchiolar epithelium were detected both on the bronchiolar surface and in peribronchiolar alveoli. The technique is being used to obtain quantitative data on the clearance rates of plutonium particles from bronchi and bronchioles.

  17. Scanning tunneling microscopy: Energetics from statistical analysis

    SciTech Connect

    Feibelman, P.J.

    1995-10-15

    The attraction between two Fe atoms adsorbed on Fe(100) should be much too weak to produce the 0.5--0.7-eV bond that has been deduced by analyzing scanning tunneling micrographs. The assumption that adatom diffusion proceeds by the same mechanism at high and low temperatures may be the source of the discrepancy.

  18. Seamless stitching of tile scan microscope images.

    PubMed

    Legesse, F B; Chernavskaia, O; Heuke, S; Bocklitz, T; Meyer, T; Popp, J; Heintzmann, R

    2015-06-01

    For diagnostic purposes, optical imaging techniques need to obtain high-resolution images of extended biological specimens in reasonable time. The field of view of an objective lens, however, is often smaller than the sample size. To image the whole sample, laser scanning microscopes acquire tile scans that are stitched into larger mosaics. The appearance of such image mosaics is affected by visible edge artefacts that arise from various optical aberrations which manifest in grey level jumps across tile boundaries. In this contribution, a technique for stitching tiles into a seamless mosaic is presented. The stitching algorithm operates by equilibrating neighbouring edges and forcing the brightness at corners to a common value. The corrected image mosaics appear to be free from stitching artefacts and are, therefore, suited for further image analysis procedures. The contribution presents a novel method to seamlessly stitch tiles captured by a laser scanning microscope into a large mosaic. The motivation for the work is the failure of currently existing methods for stitching nonlinear, multimodal images captured by our microscopic setups. Our method eliminates the visible edge artefacts that appear between neighbouring tiles by taking into account the overall illumination differences among tiles in such mosaics. The algorithm first corrects the nonuniform brightness that exists within each of the tiles. It then compensates for grey level differences across tile boundaries by equilibrating neighbouring edges and forcing the brightness at the corners to a common value. After these artefacts have been removed further image analysis procedures can be applied on the microscopic images. Even though the solution presented here is tailored for the aforementioned specific case, it could be easily adapted to other contexts where image tiles are assembled into mosaics such as in astronomical or satellite photos.

  19. Imaging soft materials with scanning tunneling microscopy.

    PubMed

    Woodward, J T; Zasadzinski, J A

    1996-01-01

    By modifying freeze-fracture replication, a standard electron microscopy fixation technique, for use with the scanning tunneling microscope (STM), a variety of soft, non-conductive biomaterials can be imaged at high resolution in three dimensions. Metal replicas make near ideal samples for STM in comparison to the original biological materials. Modifications include a 0.1 micron backing layer of silver and mounting the replicas on a fine-mesh silver filters to enhance the rigidity of the metal replica. This is required unless STM imaging is carried out in vacuum; otherwise, a liquid film of contamination physically connects the STM tip with the sample. This mechanical coupling leads to exaggerated height measurements; the enhanced rigidity of the thicker replica eliminates much of the height amplification. Further improvement was obtained by imaging in a dry nitrogen atmosphere. Calibration and reproducibility were tested with replicas of well characterized bilayers of cadmium arachidate on mica that provide regular 5.5 nm steps. We have used the STM/replica technique to examine the ripple shape and amplitude in the P beta phase of dimyristoylphosphatidyl-choline (DMPC) in water. STM images were analyzed using a cross-correlation averaging program to eliminate the effects of noise and the finite size and shapes of the metal grains that make up the replica. The correlation averaging allowed us to develop a composite ripple profile averaged over hundreds of individual ripples and different samples. The STM/replica technique is sufficiently general that it can be used to examine a variety of hydrated lipid and protein samples at a lateral resolution of about 1 nm and a vertical resolution of about 0.3 nm. PMID:9601535

  20. Metrological large range scanning probe microscope

    NASA Astrophysics Data System (ADS)

    Dai, Gaoliang; Pohlenz, Frank; Danzebrink, Hans-Ulrich; Xu, Min; Hasche, Klaus; Wilkening, Guenter

    2004-04-01

    We describe a metrological large range scanning probe microscope (LR-SPM) with an Abbe error free design and direct interferometric position measurement capability, aimed at versatile traceable topographic measurements that require nanometer accuracy. A dual-stage positioning system was designed to achieve both a large measurement range and a high measurement speed. This dual-stage system consists of a commercially available stage, referred to as nanomeasuring machine (NMM), with a motion range of 25 mm×25 mm×5 mm along x, y, and z axes, and a compact z-axis piezoelectric positioning stage (compact z stage) with an extension range of 2 μm. The metrological LR-SPM described here senses the surface using a stationary fixed scanning force microscope (SFM) head working in contact mode. During operation, lateral scanning of the sample is performed solely by the NMM. Whereas the z motion, controlled by the SFM signal, is carried out by a combination of the NMM and the compact z stage. In this case the compact z stage, with its high mechanical resonance frequency (greater than 20 kHz), is responsible for the rapid motion while the NMM simultaneously makes slower movements over a larger motion range. To reduce the Abbe offset to a minimum the SFM tip is located at the intersection of three interferometer measurement beams orientated in x, y, and z directions. To improve real time performance two high-end digital signal processing (DSP) systems are used for NMM positioning and SFM servocontrol. Comprehensive DSP firmware and Windows XP-based software are implemented, providing a flexible and user-friendly interface. The instrument is able to perform large area imaging or profile scanning directly without stitching small scanned images. Several measurements on different samples such as flatness standards, nanostep height standards, roughness standards as well as sharp nanoedge samples and 1D gratings demonstrate the outstanding metrological capabilities of the instrument.

  1. Environmental scanning electron microscope (ESEM). Final report

    SciTech Connect

    Marder, A.; Barmak, K.; Williams, D.

    1998-11-01

    The Environmental Scanning Electron Microscope (ESEM) was acquired by a grant from the Department of Energy University Research Instrumentation Program and matching funds from Lehigh University and industry. The equipment is installed as part of the electron microscopy laboratories and is being utilized on a regular basis. Over 20 graduate and undergraduate students from the Department of Materials Science and Engineering as well as other department in the University have included this instrument in their research. In addition, the ESEM has been used in several courses including MAT 427 -- Advanced Scanning Electron Microscopy, a graduate course offered every other year. Examples are given of how the ESEM has been included in the research programs.

  2. Nanofabrication with the Scanning Tunneling Microscope

    SciTech Connect

    Shedd, G.M.; Russell, P.E.

    1988-12-01

    The Precision Engineering Center has recently begun a research program into applications of STM to Nanotechnology. Few tools permit humans to control events and processes at the manometer level, and of those, the STM is the most well-suited to the task. A versatile new ultra-high-vacuum (UHV) STM is being built to study the use of STM for the manipulation of nanometer-scale particles. Part of the STM`s usefulness will be due to its being positioned directly beneath the focused ion beam (FIB). The interface of the STM with the FIB will allow the STM to take advantage of the FIB for long-range imaging and as a particle source; the FIB can in turn use the STM for in situ, high-resolution imaging of micromachined features.

  3. Manipulation of subsurface carbon nanoparticles in Bi2Sr2CaCu2O8+δ using a scanning tunneling microscope

    SciTech Connect

    Stollenwerk, A. J.; Hurley, N.; Beck, B.; Spurgeon, K.; Kidd, T. E.; Gu, G.

    2015-03-19

    In this study, we present evidence that subsurface carbon nanoparticles in Bi₂Sr₂CaCu₂O8+δ can be manipulated with nanometer precision using a scanning tunneling microscope. High resolution images indicate that most of the carbon particles remain subsurface after transport observable as a local increase in height as the particle pushes up on the surface. Tunneling spectra in the vicinity of these protrusions exhibit semiconducting characteristics with a band gap of approximately 1.8 eV, indicating that the incorporation of carbon locally alters the electronic properties near the surface.

  4. Sensitivity Improvement and Cryogenic Application of Scanning Microwave Microscope

    NASA Astrophysics Data System (ADS)

    Takahashi, Hideyuki; Imai, Yoshinori; Maeda, Atsutaka

    2015-03-01

    The technique to probe the spatial distribution of electric properties has been more important in modern material science. Scanning near-field microwave microscope (SMM) can be a powerful tool to study inhomogeneous materials. Recently we have developed scanning tunneling/microwave microscope (STM/SMM) with high sensitivity. The SMM probe is a modified coaxial resonator whose resonant frequency is 10.7 GHz and Q-factor is 1200-1300 at room temperature. It is applicable to measurements at cryogenic environment. By downsizing the resonator probe, we achieved stable operation down to liquid helium temperature. Q-factor is enhanced to 2000-3000 below 77 K. As an example of application of our STM-SMM, we present the study on inhomogeneous iron-based superconductor KxFeySe2. We successfully observed the characteristic mesoscopic phase separation of the metallic phase and the semiconducting phase by two different scanning modes; constant current mode and constant Q-factor mode. The spatial resolution is no worse than 200nm, which is comparable to curvature radius of a probe tip.

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

    SciTech Connect

    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.

  6. A cryogenic quantum gas scanning magnetic microscope

    NASA Astrophysics Data System (ADS)

    Turner, Richard; Naides, Matthew; Lai, Ruby; Disciacca, Jack; Lev, Benjamin

    2014-05-01

    Improved measurements of strongly correlated and topologically non-trivial systems open the path to a better fundamental understanding of these materials as well as the possibility for predictive design of new materials. We are working to demonstrate atom chip trapping of quantum gases to enable single-shot, large area imaging of electronic transport through these materials via detection of magnetic flux at the 10- 7 flux quantum level and below. Using the exquisite sensitivity of ultracold atoms in the form of either an atomic clock or Bose-Einstein condensate, the cryogenic atom chip technology we have recently demonstrated will provide a magnetic flux detection capability that surpasses other techniques while allowing sample temperatures spanning < 10 K to room temperature. We will report on experimental progress toward developing this novel quantum gas scanning magnetic microscope and describe our recent proposal to image topologically protected transport through a non-ideal topological insulator in a relatively model-independent fashion.

  7. A cryogenic quantum gas scanning magnetic microscope

    NASA Astrophysics Data System (ADS)

    Turner, Richard; Naides, Matthew; Lai, Ruby; Disciacca, Jack; Lev, Benjamin

    2014-05-01

    Improved measurements of strongly correlated and topologically non-trivial systems open the path to a better fundamental understanding of these materials as well as the possibility for predictive design of new materials. We are working to demonstrate atom chip trapping of quantum gases to enable single-shot, large area imaging of electronic transport through these materials via detection of magnetic flux at the 10-7 flux quantum level and below. Using the exquisite sensitivity of ultracold atoms in the form of either an atomic clock or Bose-Einstein condensate, the cryogenic atom chip technology we have recently demonstrated will provide a magnetic flux detection capability that surpasses other techniques while allowing sample temperatures spanning < 10 K to room temperature. We will report on experimental progress toward developing this novel quantum gas scanning magnetic microscope and describe our recent proposal to image topologically protected transport through a non-ideal topological insulator in a relatively model-independent fashion.

  8. A cryogenic quantum gas scanning magnetic microscope

    NASA Astrophysics Data System (ADS)

    Disciacca, Jack; Naides, Matthew; Turner, Richard; Lai, Ruby; Lev, Benjamin

    2014-03-01

    Improved measurements of strongly correlated and topologically non-trivial systems open the path to a better fundamental understanding of these materials as well as the possibility for predictive design of new materials. We are working to demonstrate atom chip trapping of quantum gases to enable single-shot, large area imaging of electronic transport through these materials via detection of magnetic flux at the 10-7 flux quantum level and below. Using the exquisite sensitivity of ultracold atoms in the form of either an atomic clock or Bose-Einstein condensate, the cryogenic atom chip technology we have recently demonstrated will provide a magnetic flux detection capability that surpasses other techniques while allowing sample temperatures spanning <10 K to room temperature. We will report on experimental progress toward developing this novel quantum gas scanning magnetic microscope and describe our recent proposal to image topologically protected transport through a non-ideal topological insulator in a relatively model-independent fashion.

  9. A cryogenic quantum gas scanning magnetic microscope

    NASA Astrophysics Data System (ADS)

    Naides, Matthew; Turner, Richard; Lai, Ruby; Disciacca, Jack; Lev, Benjamin

    2014-03-01

    Atom chip trapping of quantum gases will enable single-shot, large area imaging of transport through strongly correlated and topologically non-trivial materials via detection of magnetic flux at the 10-7 flux quantum level and below. By harnessing the extreme sensitivity of atomic clocks and Bose-Einstein condensates to external perturbations, the cryogenic atom chip technology we have recently demonstrated [1] will provide a magnetic flux detection capability that surpasses other techniques, while allowing sample temperatures spanning <10 K to room temperature. We report on experimental progress toward developing this novel quantum gas scanning magnetic microscope [1] and describe our recent proposal [2] to image topologically protected transport through a non-ideal topological insulator in a relatively model-independent fashion. U.S. DOE, BES, Division of Materials Sciences and Engineering under award #DE-SC0001823.

  10. Computer-controlled optical scanning tile microscope.

    PubMed

    Wang, C; Shumyatsky, P; Zeng, F; Zevallos, M; Alfano, R R

    2006-02-20

    A new type of computer-controlled optical scanning, high-magnification imaging system with a large field of view is described that overcomes the commonly believed incompatibility of achieving both high magnification and a large field of view. The new system incorporates galvanometer scanners, a CCD camera, and a high-brightness LED source for the fast acquisition of a large number of a high-resolution segmented tile images with a magnification of 800x for each tile. The captured segmented tile images are combined to create an effective enlarged view of a target totaling 1.6 mm x 1.2 mm in area. The speed and sensitivity of the system make it suitable for high-resolution imaging and monitoring of a small segmented area of 320 microm x 240 microm with 4 microm resolution. Each tile segment of the target can be zoomed up without loss of the high resolution. This new microscope imaging system gives both high magnification and a large field of view. This microscope can be utilized in medicine, biology, semiconductor inspection, device analysis, and quality control. PMID:16523776

  11. Conductivity map from scanning tunneling potentiometry

    NASA Astrophysics Data System (ADS)

    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.

  12. Conductivity map from scanning tunneling potentiometry.

    PubMed

    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.

  13. Conductivity map from scanning tunneling potentiometry.

    PubMed

    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. PMID:27587126

  14. Scanning tunneling microscopy studies of diamond films and optoelectronic materials

    NASA Technical Reports Server (NTRS)

    Perez, Jose M.

    1993-01-01

    In this report, we report on progress achieved from 12/1/92 to 10/1/93 under the grant entitled 'Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials'. We have set-up a chemical vapor deposition (CVD) diamond film growth system and a Raman spectroscopy system to study the nucleation and growth of diamond films with atomic resolution using scanning tunneling microscopy (STM). A unique feature of the diamond film growth system is that diamond films can be transferred directly to the ultrahigh vacuum (UHV) chamber of a scanning tunneling microscope without contaminating the films by exposure to air. The University of North Texas (UNT) provided $20,000 this year as matching funds for the NASA grant to purchase the diamond growth system. In addition, UNT provided a Coherent Innova 90S Argon ion laser, a Spex 1404 double spectrometer, and a Newport optical table costing $90,000 to set-up the Raman spectroscopy system. The CVD diamond growth system and Raman spectroscopy system will be used to grow and characterize diamond films with atomic resolution using STM as described in our proposal. One full-time graduate student and one full-time undergraduate student are supported under this grant. In addition, several graduate and undergraduate students were supported during the summer to assist in setting-up the diamond growth and Raman spectroscopy systems. We have obtained research results concerning STM of the structural and electronic properties of CVD grown diamond films, and STM and scanning tunneling spectroscopy of carbon nanotubes. In collaboration with the transmission electron microscopy (TEM) group at UNT, we have also obtained results concerning the optoelectronic material siloxene. These results were published in refereed scientific journals, submitted for publication, and presented as invited and contributed talks at scientific conferences.

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

    NASA Astrophysics Data System (ADS)

    Schuster, Gerard T.; Hanafy, Sherif; Huang, Yunsong

    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.

  16. Development and application of multiple-probe scanning probe microscopes.

    PubMed

    Nakayama, Tomonobu; Kubo, Osamu; Shingaya, Yoshitaka; Higuchi, Seiji; Hasegawa, Tsuyoshi; Jiang, Chun-Sheng; Okuda, Taichi; Kuwahara, Yuji; Takami, Kazuhiro; Aono, Masakazu

    2012-04-01

    In the research of advanced materials based on nanoscience and nanotechnology, it is often desirable to measure nanoscale local electrical conductivity at a designated position of a given sample. For this purpose, multiple-probe scanning probe microscopes (MP-SPMs), in which two, three or four scanning tunneling microscope (STM) or atomic force microscope (AFM) probes are operated independently, have been developed. Each probe in an MP-SPM is used not only for observing high-resolution STM or AFM images but also for forming an electrical contact enabling nanoscale local electrical conductivity measurement. The world's first double-probe STM (DP-STM) developed by the authors, which was subsequently modified to a triple-probe STM (TP-STM), has been used to measure the conductivities of one-dimensional metal nanowires and carbon nanotubes and also two-dimensional molecular films. A quadruple-probe STM (QP-STM) has also been developed and used to measure the conductivity of two-dimensional molecular films without the ambiguity of contact resistance between the probe and sample. Moreover, a quadruple-probe AFM (QP-AFM) with four conductive tuning-fork-type self-detection force sensing probes has been developed to measure the conductivity of a nanostructure on an insulating substrate. A general-purpose computer software to control four probes at the same time has also been developed and used in the operation of the QP-AFM. These developments and applications of MP-SPMs are reviewed in this paper.

  17. Development and Application of Multiple-Probe Scanning Probe Microscopes

    SciTech Connect

    Nakayama, T.; Kubo, O.; Shingaya, Y.; Higuchi, S.; Hasegawa, T.; Jiang, C. S.; Okuda, T.; Kuwahara, Y.; Takami, K.; Aono, M.

    2012-04-03

    the research of advanced materials based on nanoscience and nanotechnology, it is often desirable to measure nanoscale local electrical conductivity at a designated position of a given sample. For this purpose, multiple-probe scanning probe microscopes (MP-SPMs), in which two, three or four scanning tunneling microscope (STM) or atomic force microscope (AFM) probes are operated independently, have been developed. Each probe in an MP-SPM is used not only for observing high-resolution STM or AFM images but also for forming an electrical contact enabling nanoscale local electrical conductivity measurement. The world's first double-probe STM (DP-STM) developed by the authors, which was subsequently modified to a triple-probe STM (TP-STM), has been used to measure the conductivities of one-dimensional metal nanowires and carbon nanotubes and also two-dimensional molecular films. A quadruple-probe STM (QP-STM) has also been developed and used to measure the conductivity of two-dimensional molecular films without the ambiguity of contact resistance between the probe and sample. Moreover, a quadruple-probe AFM (QP-AFM) with four conductive tuning-fork-type self-detection force sensing probes has been developed to measure the conductivity of a nanostructure on an insulating substrate. A general-purpose computer software to control four probes at the same time has also been developed and used in the operation of the QP-AFM. These developments and applications of MP-SPMs are reviewed in this paper.

  18. Imaging of buried phosphorus nanostructures in silicon using scanning tunneling microscopy

    SciTech Connect

    Oberbeck, Lars; Reusch, Thilo C. G.; Hallam, Toby; Simmons, Michelle Y. E-mail: michelle.simmons@unsw.edu.au; Schofield, Steven R.; Curson, Neil J. E-mail: michelle.simmons@unsw.edu.au

    2014-06-23

    We demonstrate the locating and imaging of single phosphorus atoms and phosphorus dopant nanostructures, buried beneath the Si(001) surface using scanning tunneling microscopy. The buried dopant nanostructures have been fabricated in a bottom-up approach using scanning tunneling microscope lithography on Si(001). We find that current imaging tunneling spectroscopy is suited to locate and image buried nanostructures at room temperature and with residual surface roughness present. From these studies, we can place an upper limit on the lateral diffusion during encapsulation with low-temperature Si molecular beam epitaxy.

  19. Development of the interferometrical scanning probe microscope

    NASA Astrophysics Data System (ADS)

    Dorozhovets, N.; Hausotte, T.; Hofmann, N.; Manske, E.; Jäger, G.

    2006-08-01

    Many scanning probe microscopes (SPMs) are used as image acquisition tools in such industries as microelectronics, micromechanics, lithography and biotechnology. Conventional SPMs use piezoelectric actuators in order to move either the sample or the probe. The voltage across the piezos is taken as a position indicator. However, it is known that piezos suffer from hysteresis, and from time- and temperature-dependent creep. A solution to this problem is provided by accurate, traceable measurement of the cantilever position. An exact dimensional measurement can only take place via direct comparison with a well-known reference. The traceability of the SPM can be achieved using an interferometer, traceable to the 633 nm wavelength of the He-Ne laser. For accurate measurements the position of the cantilever must be measured in addition to the torsion and bending. This article shows the basic SPM principle as well as the addition of a cantilever position detection system. This system has been realized with a special interferometer with a quadrant diode to detect the cantilever torsion and bending. The measuring beam is focused on the cantilever backside using a lens. The reflected laser beam is split and evaluated; one part of the beam is used for the interferometrical position measurement with the other part focused onto a quadrant diode. Due to the structure of the interferometrical SPM, it can be installed in many different positioning systems with large measuring ranges, including a nanopositioning and nanomeasuring machine (NPM machine), developed at the Institute of Process Measurement and Sensor Technology of the Technische Universitaet Ilmenau.

  20. Scanning tunneling microscopy studies of topological insulators.

    PubMed

    Zhao, Kun; Lv, Yan-Feng; Ji, Shuai-Hua; Ma, Xucun; Chen, Xi; Xue, Qi-Kun

    2014-10-01

    Scanning tunneling microscopy (STM), with surface sensitivity, is an ideal tool to probe the intriguing properties of the surface state of topological insulators (TIs) and topological crystalline insulators (TCIs). We summarize the recent progress on those topological phases revealed by STM studies. STM observations have directly confirmed the existence of the topological surface states and clearly revealed their novel properties. We also discuss STM work on magnetic doped TIs, topological superconductors and crystalline symmetry-protected surface states in TCIs. The studies have greatly promoted our understanding of the exotic properties of the new topological phases, as well as put forward new challenges. STM will continue to play an important role in this rapidly growing field from the point view of both fundamental physics and applications.

  1. Luminescence induite par un microscope à effet tunnel comme sonde nanophotonique

    NASA Astrophysics Data System (ADS)

    Silly, Fabien; Charra, Fabrice

    The luminescence of nanostructured systems can be excited highly locally by the tip of a Scanning Tunneling Microscope (STM). We first present briefly the principles of this STM-induced luminescence. Then we present a review of selected results in STM-induced luminescence from the point of view of nano-scale photonics. We illustrate various contrast mechanisms with different examples of nanostructured systems. To cite this article: F. Silly, F. Charra, C. R. Physique 3 (2002) 493-500.

  2. Local density of states and scanning tunneling currents in graphene

    NASA Astrophysics Data System (ADS)

    Yang, Ling; Peres, Nuno; Tsai, Shan-Wen

    2010-03-01

    Graphene consists of an atom-thick layer of carbon atoms arranged in a honeycomb lattice, and its low-energy electronic excitations are well described as massless Dirac fermions with spin half and an additional pseudospin degree of freedom. We study local properties of graphene with isolated impurities (diagonal and non-diagonal impurity potential) such as the local electronic spectra and real-space and k-space local density of state (LDOS) maps. Using a multimode description for an scanning tunneling microscope (STM) tip, we calculate STM currents and find that strong resonances in the LDOS at finite energies lead to the presence of steps in the STM current and suppression of the Fano factor. [Ref: N. M. R. Peres, L. Yang, and S.-W. Tsai, New J. Phys. 11, 095007, (2009)

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

    SciTech Connect

    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.

  4. Investigating Intermolecular Interactions via Scanning Tunneling Microscopy: An Experiment for the Physical Chemistry Laboratory

    ERIC Educational Resources Information Center

    Pullman, David; Peterson, Karen I.

    2004-01-01

    A scanning tunneling microscope (STM) project designed as a module for the undergraduate physical chemistry laboratory is described. The effects of van der Waals interactions on the condensed-phase structure are examined by the analysis of the pattern of the monolayer structures.

  5. Study of surface plasmons with a scanning acoustic microscope

    SciTech Connect

    Bereiter-Hahn, J; Blase, C; Lozovik, Yurii E; Nazarov, Maksim M; Shkurinov, A P

    2003-05-31

    A new technique for investigating the surface plasmons by means of a scanning acoustic microscope is proposed. Within this technique, the surface electromagnetic wave (plasmon polariton) is excited by laser radiation on one side of a metal film, while a scanning acoustic microscope excites surface acoustic waves on the other side of the film. Obtained for the first time, the acoustic images of plasmons, propagating on the grating surface, demonstrate the possibility of studying the plasmon wave field distribution by means of a scanning acoustic microscope. (nonlinear optical phenomena)

  6. Direct current scanning field emission microscope integrated with existing scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Wang, Tong; Reece, Charles E.; Sundelin, Ronald M.

    2002-09-01

    Electron field emission (FE) from broad-area metal surfaces is known to occur at much lower electric field than predicted by Fowler-Nordheim law. Although micron or submicron particles are often observed at such enhanced field emission (EFE) sites, the strength and number of emitting sites and the causes of EFE strongly depend on surface preparation and handling, and the physical mechanism of EFE remains unknown. To systematically investigate the sources of this emission, a dc scanning field emission microscope (SFEM) has been built as an extension to an existing commercial scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer for emitter characterization. In the SFEM chamber of ultrahigh vacuum (approx10-9 Torr), a sample is moved laterally in a raster pattern (2.5 mum step resolution) under a high voltage anode microtip for field emission detection and localization. The sample is then transferred under vacuum by a hermetic retractable linear transporter to the SEM chamber for individual emitter site characterization. Artificial marks on the sample surface serve as references to convert x, y coordinates of emitters in the SFEM chamber to corresponding positions in the SEM chamber with a common accuracy of plus-or-minus100-200 mum in x and y. Samples designed to self-align in sample holders are used in each chamber, allowing them to retain position registration after non-in situ processing to track interesting features. No components are installed inside the SEM except the sample holder, which does not affect the routine operation of the SEM. The apparatus is a system of low cost and maintenance and significant operational flexibility. Field emission sources from planar niobium--the material used in high-field rf superconducting cavities for particle accelerator--have been studied after different surface preparations, and significantly reduced field emitter density has been achieved by refining the preparation process based on scan

  7. Imaging of single uncoated DNA molecules by scanning tunneling microscopy

    SciTech Connect

    Keller, D.; Bustamante, C.; Keller, R.W. )

    1989-07-01

    Scanning tunneling microscope images of DNA molecules adsorbed onto highly oriented pyrolytic graphite have been obtained. Three methods of deposition and sample preparation have been utilized. In the first method, a highly concentrated solution of DNA is sonicated, and a drop is deposited on freshly cleaved graphite. Under these conditions, the molecules tend to align in a parallel fashion, forming liquid-crystalline phases. In the second method, a solution of DNA is deposited directly on the graphite surface without sonication. In this case, ammonium acetate, a volatile salt, is used to decrease the amount of the residual salt crystals left after drying. In the third method, a solution containing lysed phage particles and DNA is adsorbed onto a graphite surface. The molecules are seen either isolated or in small bundles. The values of height, periodicity, and thickness observed and the handedness of the molecules are consistent with those expected for DNA. In all cases, the molecules were identified by their characteristic periodic structure and because, at higher magnification, no graphite-like structure was detectable on the surface of the molecules. Often the DNA molecules appear to adsorb in areas of the graphite that have many steps and defects. A mechanism that explains the magnitude of the tunneling currents measured in DNA is proposed. This mechanism, in turn, suggests a general method by which large insulating molecules can be rendered conductive.

  8. Microcircuit testing and fabrication, using scanning electron microscopes

    NASA Technical Reports Server (NTRS)

    Nicolas, D. P.

    1975-01-01

    Scanning electron microscopes are used to determine both user-induced damages and manufacturing defects subtle enough to be missed by conventional light microscopy. Method offers greater depth of field and increased working distances.

  9. The Scanning Electron Microscope and the Archaeologist

    ERIC Educational Resources Information Center

    Ponting, Matthew

    2004-01-01

    Images from scanning electron microscopy are now quite common and they can be of great value in archaeology. Techniques such as secondary electron imaging, backscattered electron imaging and energy-dispersive x-ray analysis can reveal information such as the presence of weevils in grain in Roman Britain, the composition of Roman coins and the…

  10. Scanning tunneling microscopy of self-assembled viral nanostructures

    NASA Astrophysics Data System (ADS)

    Anacleto, Benjamin; Steinsultz, Nat; Sharma, Prashant

    2010-03-01

    We use scanning tunneling microscopy to investigate self-assembled monolayers of M13 bacteriophages on graphite surface. The bacteriophages we use have gold binding peptide motifs on their outer protein coat (˜1μm long, ˜10 nm diameter) allowing us to self-assemble gold nanoparticles on graphite. Using scanning tunneling microscopy we are able to resolve sub-molecular structure of the protein coat of M13 bacteriophage. Scanning tunneling spectroscopy allows us to study the binding of gold nanoparticles to the peptide motif on the bacteriophage.

  11. Design and operation of a versatile, ultrahigh vacuum, low temperature scanning probe microscope

    NASA Astrophysics Data System (ADS)

    Lakhani, A. M.; Kelly, S. J.; Pearl, T. P.

    2006-04-01

    The design and operation of an ultrahigh vacuum, liquid nitrogen or helium cooled scanning probe microscope system are presented. Key construction features that reflect crucial experimental criteria will be highlighted. Following from a recently devised approach to low temperature microscopy, cooling of the Besocke-style [Surf. Sci. 181, 145 (1987)] microscope assembly is performed by housing the microscope assembly in cryogenic shields which are coupled to a low vibration flow cryostat. The microscope, however, has been designed to accommodate different types of probes including tunneling and force sensors, and this functionality offers significant flexibility. As a demonstration of temperature and microscope stability, scanning tunneling microscopy measurements at 83K, using liquid nitrogen as the cryogen, will be shown on a flat metallic Ag(111) surface. In this temperature range, we measure a drift rate of 0.34Å/h in the distance between the tip and sample as a result of ˜2mK/h temperature drift at the microscope base, and we enumerate the procedure for establishing this stability.

  12. Scanning tip microwave near field microscope

    DOEpatents

    Xiang, X.D.; Schultz, P.G.; Wei, T.

    1998-10-13

    A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an end wall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity. 17 figs.

  13. Scanning tip microwave near field microscope

    DOEpatents

    Xiang, Xiao-Dong; Schultz, Peter G.; Wei, Tao

    1998-01-01

    A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an endwall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity.

  14. Atomic-Scale Imaging and Spectroscopy Using Scanning Tunneling Microscopy.

    NASA Astrophysics Data System (ADS)

    Youngquist, Michael George

    Advances in scanning tunneling microscopy (STM) instrumentation and applications are presented. An ultrahigh vacuum (UHV) scanning tunneling microscope incorporating computer-controlled two-dimensional sample translation and in vacuo tip and sample transfer was developed. Its performance is documented through large-area and atomic -resolution imaging of highly stepped Si(111) 7 x 7 reconstructed surfaces and physisorbed clusters on graphite. An STM with automated approach and intra-Dewar spring suspension was developed for operation in cryogenic liquids. A high performance digital signal processor (DSP) based control system was constructed, and software with advanced spectroscopic imaging and data processing capabilities was developed. The feasibility of individual-molecule vibrational spectroscopy via STM-detected inelastic electron tunneling is assessed. In preliminary experiments, a low-temperature STM was used for energy gap and phonon spectroscopy of superconducting Pb films. The first STM observation of phonon density of states effects in a superconductor is reported. A systematic UHV STM imaging and spectroscopy study of 2H-MoS_2 was conducted. Atom -resolved images from three distinct imaging modes are presented. Occasional appearance of negative differential resistance (NDR) in I vs. V measurements is traced to changing tip electronic structure rather than localized surface states. Other potential NDR mechanisms are discussed including electron trap charging and resonant tunneling through a double-barrier quantum well structure arising from layer separation in the MoS_2 crystal. DNA was imaged at atomic resolution with a UHV STM. Images show double-helical structure, base pairs, and atomic-scale substructure. Experimental STM profiles have atom-for-atom correlation with the A-DNA van der Waals surface. This work demonstrates the potential of the STM for characterization of large biomolecular structures. Impurity-pinned steps on silicon and gold surfaces

  15. A scanning Hall probe microscope for high resolution magnetic imaging down to 300 mK

    NASA Astrophysics Data System (ADS)

    Khotkevych, V. V.; Milošević, M. V.; Bending, S. J.

    2008-12-01

    We present the design, construction, and performance of a low-temperature scanning Hall probe microscope with submicron lateral resolution and a large scanning range. The detachable microscope head is mounted on the cold flange of a commercial H3e-refrigerator (Oxford Instruments, Heliox VT-50) and operates between room temperature and 300 mK. It is fitted with a three-axis slip-stick nanopositioner that enables precise in situ adjustment of the probe location within a 6×6×7 mm3 space. The local magnetic induction at the sample surface is mapped with an easily changeable microfabricated Hall probe [typically GsAs/AlGaAs or AlGaAs/InGaAs/GaAs Hall sensors with integrated scanning tunnel microscopy (STM) tunneling tips] and can achieve minimum detectable fields ⩾10 mG/Hz1/2. The Hall probe is brought into very close proximity to the sample surface by sensing and controlling tunnel currents at the integrated STM tip. The instrument is capable of simultaneous tunneling and Hall signal acquisition in surface-tracking mode. We illustrate the potential of the system with images of superconducting vortices at the surface of a Nb thin film down to 372 mK, and also of labyrinth magnetic-domain patterns of an yttrium iron garnet film captured at room temperature.

  16. Atomic-scale imaging of DNA using scanning tunnelling microscopy

    NASA Astrophysics Data System (ADS)

    Driscoll, Robert J.; Youngquist, Michael G.; Baldeschwieler, John D.

    1990-07-01

    THE scanning tunnelling microscope (STM) has been used to visualize DNA1 under water2, under oil3 and in air4-6. Images of single-stranded DNA have shown that submolecular resolution is possible7. Here we describe atomic-resolution imaging of duplex DNA. Topographic STM images of uncoated duplex DNA on a graphite substrate obtained in ultra-high vacuum are presented that show double-helical structure, base pairs, and atomic-scale substructure. Experimental STM profiles show excellent correlation with atomic contours of the van der Waals surface of A-form DNA derived from X-ray crystallography. A comparison of variations in the barrier to quantum mechanical tunnelling (barrier-height) with atomic-scale topography shows correlation over the phosphate-sugar backbone but anticorrelation over the base pairs. This relationship may be due to the different chemical characteristics of parts of the molecule. Further investigation of this phenomenon should lead to a better understanding of the physics of imaging adsorbates with the STM and may prove useful in sequencing DNA. The improved resolution compared with previously published STM images of DNA may be attributable to ultra-high vacuum, high data-pixel density, slow scan rate, a fortuitously clean and sharp tip and/or a relatively dilute and extremely clean sample solution. This work demonstrates the potential of the STM for characterization of large biomolecular structures, but additional development will be required to make such high resolution imaging of DNA and other large molecules routine.

  17. Observation of biological samples using a scanning microwave microscope.

    PubMed

    Park, Jewook; Hyun, S; Kim, A; Kim, T; Char, K

    2005-01-01

    We present the application of a scanning microwave microscope technique to biological samples. Since dielectric properties of most biological samples originate mainly from the water they contain, we were able to obtain microscope images of biological samples by our scanning microwave microscope technique. As a model system, we have measured the electrical properties of water in the microwave region. The high dielectric constant and the large loss tangent of water were verified. Furthermore, we have measured the properties of water with differing amounts of sodium chloride concentration ranging from de-ionized water to the saturated solution. We have observed a significant change in the resonant frequency and Q value of the resonator as a function of sodium chloride concentration. The concentration dependence of the signals shows that our scanning microwave microscope technique can be useful for investigating the local electric behavior of biological samples with a simple model of ionic conduction.

  18. Design and performance of a practical variable-temperature scanning tunneling potentiometry system.

    PubMed

    Rozler, M; Beasley, M R

    2008-07-01

    We have constructed a scanning tunneling potentiometry system capable of simultaneously mapping the transport-related electrochemical potential of a biased sample along with its surface topography. Combining a novel sample biasing technique with a continuous current-nulling feedback scheme pushes the noise performance of the measurement to its fundamental limit--the Johnson noise of the scanning tunneling microscope (STM) tunnel junction. The resulting 130 nV voltage sensitivity allows us to spatially resolve local potentials at scales down to 2 nm, while maintaining angstrom scale STM imaging, all at scan sizes of up to 15 microm. A millimeter-range two-dimensional coarse positioning stage and the ability to operate from liquid helium to room temperature with a fast turn-around time greatly expand the versatility of the instrument. By performing studies of several model systems, we discuss the implications of various types of surface morphology for potentiometric measurements.

  19. Fundamental quantum noise mapping with tunnelling microscopes tested at surface structures of subatomic lateral size.

    PubMed

    Herz, Markus; Bouvron, Samuel; Ćavar, Elizabeta; Fonin, Mikhail; Belzig, Wolfgang; Scheer, Elke

    2013-10-21

    We present a measurement scheme that enables quantitative detection of the shot noise in a scanning tunnelling microscope while scanning the sample. As test objects we study defect structures produced on an iridium single crystal at low temperatures. The defect structures appear in the constant current images as protrusions with curvature radii well below the atomic diameter. The measured power spectral density of the noise is very near to the quantum limit with Fano factor F = 1. While the constant current images show detailed structures expected for tunnelling involving d-atomic orbitals of Ir, we find the current noise to be without pronounced spatial variation as expected for shot noise arising from statistically independent events.

  20. Dental Wear: A Scanning Electron Microscope Study

    PubMed Central

    Levrini, Luca; Di Benedetto, Giulia

    2014-01-01

    Dental wear can be differentiated into different types on the basis of morphological and etiological factors. The present research was carried out on twelve extracted human teeth with dental wear (three teeth showing each type of wear: erosion, attrition, abrasion, and abfraction) studied by scanning electron microscopy (SEM). The study aimed, through analysis of the macro- and micromorphological features of the lesions (considering the enamel, dentin, enamel prisms, dentinal tubules, and pulp), to clarify the different clinical and diagnostic presentations of dental wear and their possible significance. Our results, which confirm current knowledge, provide a complete overview of the distinctive morphology of each lesion type. It is important to identify the type of dental wear lesion in order to recognize the contributing etiological factors and, consequently, identify other more complex, nondental disorders (such as gastroesophageal reflux, eating disorders). It is clear that each type of lesion has a specific morphology and mechanism, and further clinical studies are needed to clarify the etiological processes, particularly those underlying the onset of abfraction. PMID:25548769

  1. Microwave Spectroscopy of Superconductors with a Scanning Low Temperature Near-Field Microwave Microscope

    NASA Astrophysics Data System (ADS)

    Imtiaz, Atif; Anlage, Steven

    2001-03-01

    We have developed a new tool to study the microwave conductivity and other properties of superconductors: The Cryogenic scanning near-field microwave microscope integrated with STM feedback. This instrument allows localized spectroscopic measurements of these materials in a non-destructive way, at both low and high frequencies. We will discuss results that show it high spatial resolution on metal and superconducting films in the frequency range of 7-11 GHz and compare it to simultaneously-acquired topography of the surface using a scanning tunneling microscope. The high spatial resolution allows us to image the grains and grain boundaries in superconductors, while facilitating local spectroscopy. The instrument allows us to study the electronic properties from STM and the microwave spectroscopic properties of the materials from the microwave microscope simultaneously, and independently of each other. We will also discuss a model of the microscope, which gives a quantitative understanding of the frequency shift and Q, demonstrating that this microscope is qualitatively similar to our earlier version.^1 We shall present images of superconducting films in the critical state and discuss the possibility of imaging magnetic vortices at microwave frequencies. Reference: 1 [D.E.Steinhauer, C.P.vlahacos, S.K.Dutta, B.J.Feenstra, F.C.Wellstood, and Steven M.Anlage, "Quantitative Imaging of Sheet Resistance with a Scanning Near-Field Microwave Microscope," Appl. Phys. Lett. 72, 861 (1998)].

  2. Scanning Tunneling Spectroscopy Studies of Multiband and Unconventional Superconductivity

    NASA Astrophysics Data System (ADS)

    Fridman, Igor

    Scanning tunneling spectroscopy at low temperature and in a magnetic field has been used to study multiband superconductivity in 2H-NbSe 2, superconductivity in iron chalcogenides and pnictides, and the superconducting proximity effect between a high-Tc cuprate and a half-metallic manganite. In superconductors with complex band structures, pairing can involve multiple bands with multiple superconducting gaps. To search for new phenomena, a scanning tunneling microscope that operates at 300 mK was specially designed for a magnetic field of up to 9 T to be applied parallel to the sample surface. In the mixed state, field-induced supercurrents give the Cooper pairs a finite superfluid momentum, enabling the study of the quasiparticle density of states spectrum using the Doppler energy shift as a perturbation. This technique was applied to 2H-NbSe2, a layered s-wave superconductor with a multi-sheeted and anisotropic Fermi surface. We identify spectral features that evolve with field, and a zero-bias conductance that changes slope at 0.7 T. Our observations are interpreted as signatures of multiband superconductivity with different gaps on parts of the Fermi surface. Spatial conductance maps on the surface of 2H-NbSe 2 revealed a field-dependent stripe pattern that can be quantitatively identified as the lateral projection of a subsurface vortex lattice. The dominant periodicity of the stripes undergoes a discrete shift at 0.7 T, applied along [100], which is evidence for a novel reorientation transition of the inplane lattice. This observation is correlated with multiband characteristics seen in bulk measurements, implicating the multiband pairing of 2 H-NbSe2 in the transition. This technique demonstrates a general method for probing multiband superconductivity, as well as studying the subsurface vortex lattice and isolated vortices in real space. Measurements down to 300 mK on Fe1+yTe 1-xSex showed a gap structure and the presence of low-energy quasiparticles, which

  3. Multi-perspective scanning microscope based on Talbot effect

    NASA Astrophysics Data System (ADS)

    Sun, Yangyang; Pang, Shuo

    2016-01-01

    We report a multi-perspective scanning microscope based on the Talbot effect of a periodic focal spot array. Talbot illumination decouples the lateral scanning and the focal spots tuning. Large field of view fluorescence Talbot Microscope has been demonstrated by globally changing the incident wavefront gradient. Here, we explore the design freedom of adjusting the wavefront locally within each period and thus engineer the point spread function of the focal spots. We demonstrate an imaging system capable of reconstructing multi-perspective microscopic images in both bright field and fluorescence mode. With the multi-perspective imaging capability, we envision a more robust microscopic imaging system for large field of view fluorescence microscopy applications. This method is also suitable for compact imaging systems for multi-layer microfluidic systems.

  4. Influence of mechanical noise inside a scanning electron microscope

    SciTech Connect

    Gaudenzi de Faria, Marcelo; Haddab, Yassine Le Gorrec, Yann; Lutz, Philippe

    2015-04-15

    The scanning electron microscope is becoming a popular tool to perform tasks that require positioning, manipulation, characterization, and assembly of micro-components. However, some of these applications require a higher level of performance with respect to dynamics and precision of positioning. One limiting factor is the presence of unidentified noises and disturbances. This work aims to study the influence of mechanical disturbances generated by the environment and by the microscope, identifying how these can affect elements in the vacuum chamber. To achieve this objective, a dedicated setup, including a high-resolution vibrometer, was built inside the microscope. This work led to the identification and quantification of main disturbances and noise sources acting on a scanning electron microscope. Furthermore, the effects of external acoustic excitations were analysed. Potential applications of these results include noise compensation and real-time control for high accuracy tasks.

  5. Performance of automatic scanning microscope for nuclear emulsion experiments

    NASA Astrophysics Data System (ADS)

    Güler, A. Murat; Altınok, Özgür

    2015-12-01

    The impressive improvements in scanning technology and methods let nuclear emulsion to be used as a target in recent large experiments. We report the performance of an automatic scanning microscope for nuclear emulsion experiments. After successful calibration and alignment of the system, we have reached 99% tracking efficiency for the minimum ionizing tracks that penetrating through the emulsions films. The automatic scanning system is successfully used for the scanning of emulsion films in the OPERA experiment and plan to use for the next generation of nuclear emulsion experiments.

  6. Performance of automatic scanning microscope for nuclear emulsion experiments

    SciTech Connect

    Güler, A. Murat; Altınok, Özgür

    2015-12-31

    The impressive improvements in scanning technology and methods let nuclear emulsion to be used as a target in recent large experiments. We report the performance of an automatic scanning microscope for nuclear emulsion experiments. After successful calibration and alignment of the system, we have reached 99% tracking efficiency for the minimum ionizing tracks that penetrating through the emulsions films. The automatic scanning system is successfully used for the scanning of emulsion films in the OPERA experiment and plan to use for the next generation of nuclear emulsion experiments.

  7. Smart align -- A new tool for robust non-rigid registration of scanning microscope data

    DOE PAGES

    Jones, Lewys; Yang, Hao; Pennycook, Timothy J.; Marshall, Matthew S. J.; Van Aert, Sandra; Browning, Nigel D.; Castell, Martin R.; Nellist, Peter D.

    2015-07-10

    Many microscopic investigations of materials may benefit from the recording of multiple successive images. This can include techniques common to several types of microscopy such as frame averaging to improve signal-to-noise ratios (SNR) or time series to study dynamic processes or more specific applications. In the scanning transmission electron microscope, this might include focal series for optical sectioning or aberration measurement, beam damage studies or camera-length series to study the effects of strain; whilst in the scanning tunnelling microscope, this might include bias voltage series to probe local electronic structure. Whatever the application, such investigations must begin with the carefulmore » alignment of these data stacks, an operation that is not always trivial. In addition, the presence of low-frequency scanning distortions can introduce intra-image shifts to the data. Here, we describe an improved automated method of performing non-rigid registration customised for the challenges unique to scanned microscope data specifically addressing the issues of low-SNR data, images containing a large proportion of crystalline material and/or local features of interest such as dislocations or edges. Careful attention has been paid to artefact testing of the non-rigid registration method used, and the importance of this registration for the quantitative interpretation of feature intensities and positions is evaluated.« less

  8. Smart align -- A new tool for robust non-rigid registration of scanning microscope data

    SciTech Connect

    Jones, Lewys; Yang, Hao; Pennycook, Timothy J.; Marshall, Matthew S. J.; Van Aert, Sandra; Browning, Nigel D.; Castell, Martin R.; Nellist, Peter D.

    2015-07-10

    Many microscopic investigations of materials may benefit from the recording of multiple successive images. This can include techniques common to several types of microscopy such as frame averaging to improve signal-to-noise ratios (SNR) or time series to study dynamic processes or more specific applications. In the scanning transmission electron microscope, this might include focal series for optical sectioning or aberration measurement, beam damage studies or camera-length series to study the effects of strain; whilst in the scanning tunnelling microscope, this might include bias voltage series to probe local electronic structure. Whatever the application, such investigations must begin with the careful alignment of these data stacks, an operation that is not always trivial. In addition, the presence of low-frequency scanning distortions can introduce intra-image shifts to the data. Here, we describe an improved automated method of performing non-rigid registration customised for the challenges unique to scanned microscope data specifically addressing the issues of low-SNR data, images containing a large proportion of crystalline material and/or local features of interest such as dislocations or edges. Careful attention has been paid to artefact testing of the non-rigid registration method used, and the importance of this registration for the quantitative interpretation of feature intensities and positions is evaluated.

  9. Scanning Transmission X-ray Microscope Control Program

    2005-08-05

    User Interface and control software or C++ to run on specifically equipped computer running Windows Operating Systems. Program performs specific control functions required to operate Interferometer controlled scanning transmission X-ray microscopes at ALS beamlines 532 and 11.0.2. Graphical user interface facilitates control, display images and spectra.

  10. Scanning electron microscope facility for examination of radioactive materials

    SciTech Connect

    Gibson, J.R.; Braski, D.N.

    1985-02-01

    An AMRAY model 1200B scanning electron microscope was modified to permit remote examination of radioactive specimens. Features of the modification include pneumatic vibration isolation of the column, motorized stage controls, improvements for monitoring vacuum, and a system for changing filaments without entering the hot cell.

  11. Undulator based scanning microscope at the National Synchrotron Light Source

    SciTech Connect

    Rarback, H.; Shu, D.; Ade, H.; Jacobsen, C.; Kirz, J.; McNulty, I.; Rosser, R.

    1986-01-01

    A second generation scanning soft x-ray microscope is under construction, designed to utilize the dramatic increase in source bightness available at the soft x-ray undulator. The new instrument is expected to reduce image acquisition time by a factor of about 100, and to improve resolution, stability, and reproducibility.

  12. The fragile X: a scanning electron microscope study.

    PubMed Central

    Harrison, C J; Jack, E M; Allen, T D; Harris, R

    1983-01-01

    Scanning electron microscopy (SEM) has been used to study the fragile X chromosome. The fragile site appears as an isochromatid gap in the majority of cases, confirming light microscope (LM) observations. SEM has allowed a more precise location of the fragile site to the Xq27 . 3 region. Images PMID:6684694

  13. Nanoscale Spectroscopy with a Scanning Near-Field Infrared Microscope

    NASA Astrophysics Data System (ADS)

    Michaels, Chris; Richter, Lee; Cavanagh, Richard; Stranick, Stephan

    2001-03-01

    The development of a scanning near-field microscope that allows the measurement of infrared spectra with nanoscale spatial resolution will be described. This instrument couples the spatial resolution of a scanning probe microscope with the chemical specificity of vibrational spectroscopy. This combination allows the in situ mapping of chemical functional groups with subwavelength spatial resolution. Infrared transmission images of a micropatterned thin gold film will be presented that demonstrate spatial resolution of λ/10 at 3.4 micrometers in the absence of artifacts due to topography-induced contrast. Near-field infrared absorption spectra of thin polymer films that demonstrate sensitivity sufficient for sub-diffraction absorption imaging in the aliphatic and aromatic C-H stretching regions will also be presented. Images of thin film polymer blends and nanocomposites acquired in the C-H stretching region will be used to benchmark the nanoscale chemical imaging capabilities of this microscope.

  14. Focal depth measurement of scanning helium ion microscope

    SciTech Connect

    Guo, Hongxuan; Itoh, Hiroshi; Wang, Chunmei; Zhang, Han; Fujita, Daisuke

    2014-07-14

    When facing the challenges of critical dimension measurement of complicated nanostructures, such as of the three dimension integrated circuit, characterization of the focal depth of microscopes is important. In this Letter, we developed a method for characterizing the focal depth of a scanning helium ion microscope (HIM) by using an atomic force microscope tip characterizer (ATC). The ATC was tilted in a sample chamber at an angle to the scanning plan. Secondary electron images (SEIs) were obtained at different positions of the ATC. The edge resolution of the SEIs shows the nominal diameters of the helium ion beam at different focal levels. With this method, the nominal shapes of the helium ion beams were obtained with different apertures. Our results show that a small aperture is necessary to get a high spatial resolution and high depth of field images with HIM. This work provides a method for characterizing and improving the performance of HIM.

  15. Laser scan microscope and infrared laser scan microcope: two important tools for device testing

    NASA Astrophysics Data System (ADS)

    Ziegler, Eberhard

    1991-03-01

    The optical beam induced current (OBIC) produced in devices by a laser scan microscope (LSM) is used to localize hot spots, leakage currents, electrostatic discharge defects and weak points. The LSM also allows photoluminescence measurements with high spatial and energy resolution. Using the infrared laser scan microscope (IR LSM), defects in the metallization and latch-up sensitive region could be detected from the back of the device.

  16. The scanning ion conductance microscope for cellular physiology.

    PubMed

    Lab, Max J; Bhargava, Anamika; Wright, Peter T; Gorelik, Julia

    2013-01-01

    The quest for nonoptical imaging methods that can surmount light diffraction limits resulted in the development of scanning probe microscopes. However, most of the existing methods are not quite suitable for studying biological samples. The scanning ion conductance microscope (SICM) bridges the gap between the resolution capabilities of atomic force microscope and scanning electron microscope and functional capabilities of conventional light microscope. A nanopipette mounted on a three-axis piezo-actuator, scans a sample of interest and ion current is measured between the pipette tip and the sample. The feedback control system always keeps a certain distance between the sample and the pipette so the pipette never touches the sample. At the same time pipette movement is recorded and this generates a three-dimensional topographical image of the sample surface. SICM represents an alternative to conventional high-resolution microscopy, especially in imaging topography of live biological samples. In addition, the nanopipette probe provides a host of added modalities, for example using the same pipette and feedback control for efficient approach and seal with the cell membrane for ion channel recording. SICM can be combined in one instrument with optical and fluorescent methods and allows drawing structure-function correlations. It can also be used for precise mechanical force measurements as well as vehicle to apply pressure with precision. This can be done on living cells and tissues for prolonged periods of time without them loosing viability. The SICM is a multifunctional instrument, and it is maturing rapidly and will open even more possibilities in the near future.

  17. The Scanning Theremin Microscope: A Model Scanning Probe Instrument for Hands-On Activities

    ERIC Educational Resources Information Center

    Quardokus, Rebecca C.; Wasio, Natalie A.; Kandel, S. Alex

    2014-01-01

    A model scanning probe microscope, designed using similar principles of operation to research instruments, is described. Proximity sensing is done using a capacitance probe, and a mechanical linkage is used to scan this probe across surfaces. The signal is transduced as an audio tone using a heterodyne detection circuit analogous to that used in…

  18. Topography and transport properties of oligo(phenylene ethynylene) molecular wires studied by scanning tunneling microscopy

    NASA Technical Reports Server (NTRS)

    Dholakia, Geetha R.; Fan, Wendy; Koehne, Jessica; Han, Jie; Meyyappan, M.

    2003-01-01

    Conjugated phenylene(ethynylene) molecular wires are of interest as potential candidates for molecular electronic devices. Scanning tunneling microscopic study of the topography and current-voltage (I-V) characteristics of self-assembled monolayers of two types of molecular wires are presented here. The study shows that the topography and I-Vs, for small scan voltages, of the two wires are quite similar and that the electronic and structural changes introduced by the substitution of an electronegative N atom in the central phenyl ring of these wires does not significantly alter the self-assembly or the transport properties.

  19. 'Oxide-free' tip for scanning tunneling microscopy

    NASA Technical Reports Server (NTRS)

    Colton, R. J.; Baker, S. M.; Baldeschwieler, J. D.; Kaiser, W. J.

    1987-01-01

    A new tip for scanning tunneling microscopy and a tip repair procedure that allows one to reproducibly obtain atomic images of highly oriented pyrolytic graphite with previously inoperable tips are reported. The tips are shown to be relatively oxide-free and highly resistant to oxidation. The tips are fabricated with graphite by two distinct methods.

  20. Digital signal processor control of scanned probe microscopes

    NASA Astrophysics Data System (ADS)

    Baselt, David R.; Clark, Steven M.; Youngquist, Michael G.; Spence, Charles F.; Baldeschwieler, John D.

    1993-07-01

    Digital signal processors have made it possible to control scanned probe microscopes using straightforward software emulations of analog circuits. Using a system consisting of a commercially available digital signal processor board interfaced to analog I/O, we have developed algorithms for self-optimizing feedback, raster generation (with hysteresis correction, sample tilt compensation, and scan rotation), lock-in detection, and automatic tip-sample approach. We also discuss an instruction parser that takes advantage of the digital architecture to allow automatic operation for extended periods.

  1. Application of in vivo laser scanning microscope in dermatology

    NASA Astrophysics Data System (ADS)

    Lademann, Juergen; Richter, H.; Otberg, N.; Lawrenz, F.; Blume-Peytavi, U.; Sterry, W.

    2003-10-01

    The state of the art of in-vivo and in-vitro penetration measurements of topically applied substances is described. Only optical techniques represent online measuring methods based on the absorption or scattering properties of the topically applied substances. Laser scanning microscopy (LSM) has become a promising method for investigations in dermatology and skin physiology, after it was possible to analyze the skin surface on any body side in-vivo. In the present paper the application of a dermatological laser scanning microscope for penetration and distribution measurements of topically applied substances is described. The intercellular and follicular penetration pathways were studied.

  2. Multiple-probe scanning probe microscopes for nanoarchitectonic materials science

    NASA Astrophysics Data System (ADS)

    Nakayama, Tomonobu; Shingaya, Yoshitaka; Aono, Masakazu

    2016-11-01

    Nanoarchitectonic systems are of interest for utilizing a vast range of nanoscale materials for future applications requiring a huge number of elemental nanocomponents. To explore the science and technology of nanoarchitectonics, advanced characterization tools that can deal with both nanoscale objects and macroscopically extended nanosystems are demanded. Multiple-probe scanning probe microscopes (MP-SPMs) are powerful tools that meet this demand because they take the advantages of conventional scanning probe microscopes and realize atomically precise electrical measurements, which cannot be done with conventional microprobing systems widely used in characterizing materials and devices. Furthermore, an MP-SPM can be used to operate some nanoarchitectonic systems. In this review, we overview the indispensable features of MP-SPMs together with the past, present and future of MP-SPM technology.

  3. Surface Analysis by Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    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

  4. Design of Scattering Scanning Near-Field Optical Microscope

    NASA Astrophysics Data System (ADS)

    Schrecongost, Dustin

    The primary objective of this work is to construct a fully functional scattering type Scanning Near-field Optical Microscope (s-SNOM), and to understand the working mechanisms behind it. An s-SNOM is an instrument made up of two separate instruments working in unison. One instrument is a scanning optical microscope focusing light onto a raster scanning sample surface combined with an interferometer set up. The second instrument is an Atomic Force Microscope (AFM) operating in noncontact mode. The AFM uses a small probe that interacts with the raster scanning sample surface to map out the topography of the of the sample surface. An s-SNOM uses both of these instruments simultaneously by focusing the light of the optical microscope onto the probe of the AFM. This probe acts as a nano-antenna and confines the light allowing for light-matter interaction to be inferred far below the resolution of the diffraction limit of light. This specific s-SNOM system is unique to others by having a controllable environment. It is high vacuum compatible and variable temperature. In addition, it is efficient at collecting scattered light due to the focusing objective being a partial elliptical mirror which collects 360° of light around the major axis. This s-SNOM system will be used for direct imaging of surface plasmons. Intended works are inducing surface plasmons on InSe thin films, and seeing the enhancement effect of introducing Au nano-rods. Also dielectric properties of materials will be interpreted such as the metal to insulator phase transition of NbO2.

  5. Resolution enhancement in a double-helix phase engineered scanning microscope (RESCH microscope) (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Jesacher, Alexander; Ritsch-Marte, Monika; Piestun, Rafael

    2015-08-01

    Recently we introduced RESCH microscopy [1] - a scanning microscope that allows slightly refocusing the sample after the acquisition has been performed, solely by performing appropriate data post-processing. The microscope features a double-helix phase-engineered emission point spread function in combination with camera-based detection. Based on the principle of transverse resolution enhancement in Image Scanning Microscopy [2,3], we demonstrate similar resolution improvement in RESCH. Furthermore, we outline a pathway for how the collected 3D sample information can be used to construct sharper optical sections. [1] A. Jesacher, M. Ritsch-Marte and R. Piestun, accepted for Optica. [2] C.J.R. Sheppard, "Super-resolution in Confocal imaging," Optik, 80, 53-54 (1988). [3] C.B. Müller and J. Enderlein "Image Scanning Microscopy," Phys. Rev. Lett. 104, 198101 (2010).

  6. Automatic analysis for neuron by confocal laser scanning microscope

    NASA Astrophysics Data System (ADS)

    Satou, Kouhei; Aoki, Yoshimitsu; Mataga, Nobuko; Hensh, Takao K.; Taki, Katuhiko

    2005-12-01

    The aim of this study is to develop a system that recognizes both the macro- and microscopic configurations of nerve cells and automatically performs the necessary 3-D measurements and functional classification of spines. The acquisition of 3-D images of cranial nerves has been enabled by the use of a confocal laser scanning microscope, although the highly accurate 3-D measurements of the microscopic structures of cranial nerves and their classification based on their configurations have not yet been accomplished. In this study, in order to obtain highly accurate measurements of the microscopic structures of cranial nerves, existing positions of spines were predicted by the 2-D image processing of tomographic images. Next, based on the positions that were predicted on the 2-D images, the positions and configurations of the spines were determined more accurately by 3-D image processing of the volume data. We report the successful construction of an automatic analysis system that uses a coarse-to-fine technique to analyze the microscopic structures of cranial nerves with high speed and accuracy by combining 2-D and 3-D image analyses.

  7. Holders for in situ treatments of scanning tunneling microscopy tips.

    PubMed

    Ishida, Nobuyuki; Subagyo, Agus; Ikeuchi, Akira; Sueoka, Kazuhisa

    2009-09-01

    We have developed holders for scanning tunneling microscopy tips that can be used for in situ treatments of the tips, such as electron bombardment (EB) heating, ion sputtering, and the coating of magnetic materials. The holders can be readily installed into the transfer paths and do not require any special type of base stages. Scanning electron microscopy is used to characterize the tip apex after EB heating. Also, spin-polarized scanning tunneling spectroscopy using an Fe coated W tip on the Cr(001) single crystal surface is performed in order to confirm both the capability of heating a tip up to about 2200 K and the spin sensitivity of the magnetically coated tip.

  8. A new clustering algorithm for scanning electron microscope images

    NASA Astrophysics Data System (ADS)

    Yousef, Amr; Duraisamy, Prakash; Karim, Mohammad

    2016-04-01

    A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with the sample atoms, producing various signals that are collected by detectors. The gathered signals contain information about the sample's surface topography and composition. The electron beam is generally scanned in a raster scan pattern, and the beam's position is combined with the detected signal to produce an image. The most common configuration for an SEM produces a single value per pixel, with the results usually rendered as grayscale images. The captured images may be produced with insufficient brightness, anomalous contrast, jagged edges, and poor quality due to low signal-to-noise ratio, grained topography and poor surface details. The segmentation of the SEM images is a tackling problems in the presence of the previously mentioned distortions. In this paper, we are stressing on the clustering of these type of images. In that sense, we evaluate the performance of the well-known unsupervised clustering and classification techniques such as connectivity based clustering (hierarchical clustering), centroid-based clustering, distribution-based clustering and density-based clustering. Furthermore, we propose a new spatial fuzzy clustering technique that works efficiently on this type of images and compare its results against these regular techniques in terms of clustering validation metrics.

  9. Scanning tunneling spectroscopy study of the Dirac spectrum of germanene.

    PubMed

    Walhout, C J; Acun, A; Zhang, L; Ezawa, M; Zandvliet, H J W

    2016-07-20

    The temperature dependence of the density of states of germanene, synthesized on Ge/Pt crystals, has been investigated with scanning tunneling spectroscopy. After correction for thermal broadening, a virtually perfect V-shaped density of states, which is a hallmark of a two-dimensional Dirac system, has been found. In an attempt to directly measure the energy dispersion relation via quasiparticle interference we have recorded spatial maps of the differential conductivity near the edges and defects of germanene. Unfortunately, we did not find any sign of Friedel oscillations. The absence of these Friedel oscillations hints to the occurrence of Klein tunneling. PMID:27227390

  10. Scanning tunneling potentiometry implemented into a multi-tip setup by software.

    PubMed

    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.

  11. Scanning tunneling potentiometry implemented into a multi-tip setup by software

    NASA Astrophysics Data System (ADS)

    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 } ) R 3 0 ∘ 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 } ) R 3 0 ∘ and Si(111) - (7 × 7) surfaces.

  12. Scanning optical microscope with long working distance objective

    DOEpatents

    Cloutier, Sylvain G.

    2010-10-19

    A scanning optical microscope, including: a light source to generate a beam of probe light; collimation optics to substantially collimate the probe beam; a probe-result beamsplitter; a long working-distance, infinity-corrected objective; scanning means to scan a beam spot of the focused probe beam on or within a sample; relay optics; and a detector. The collimation optics are disposed in the probe beam. The probe-result beamsplitter is arranged in the optical paths of the probe beam and the resultant light from the sample. The beamsplitter reflects the probe beam into the objective and transmits resultant light. The long working-distance, infinity-corrected objective is also arranged in the optical paths of the probe beam and the resultant light. It focuses the reflected probe beam onto the sample, and collects and substantially collimates the resultant light. The relay optics are arranged to relay the transmitted resultant light from the beamsplitter to the detector.

  13. Analytical scanning evanescent microwave microscope and control stage

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen; Duewer, Fred; Yang, Hai Tao; Lu, Yalin

    2009-06-23

    A scanning evanescent microwave microscope (SEMM) that uses near-field evanescent electromagnetic waves to probe sample properties is disclosed. The SEMM is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The SEMM has the ability to map dielectric constant, loss tangent, conductivity, electrical impedance, and other electrical parameters of materials. Such properties are then used to provide distance control over a wide range, from to microns to nanometers, over dielectric and conductive samples for a scanned evanescent microwave probe, which enable quantitative non-contact and submicron spatial resolution topographic and electrical impedance profiling of dielectric, nonlinear dielectric and conductive materials. The invention also allows quantitative estimation of microwave impedance using signals obtained by the scanned evanescent microwave probe and quasistatic approximation modeling. The SEMM can be used to measure electrical properties of both dielectric and electrically conducting materials.

  14. Analytical scanning evanescent microwave microscope and control stage

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen; Duewer, Fred; Yang, Hai Tao; Lu, Yalin

    2013-01-22

    A scanning evanescent microwave microscope (SEMM) that uses near-field evanescent electromagnetic waves to probe sample properties is disclosed. The SEMM is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The SEMM has the ability to map dielectric constant, loss tangent, conductivity, electrical impedance, and other electrical parameters of materials. Such properties are then used to provide distance control over a wide range, from to microns to nanometers, over dielectric and conductive samples for a scanned evanescent microwave probe, which enable quantitative non-contact and submicron spatial resolution topographic and electrical impedance profiling of dielectric, nonlinear dielectric and conductive materials. The invention also allows quantitative estimation of microwave impedance using signals obtained by the scanned evanescent microwave probe and quasistatic approximation modeling. The SEMM can be used to measure electrical properties of both dielectric and electrically conducting materials.

  15. Pupil engineering for a confocal reflectance line-scanning microscope

    NASA Astrophysics Data System (ADS)

    Patel, Yogesh G.; Rajadhyaksha, Milind; DiMarzio, Charles A.

    2011-03-01

    Confocal reflectance microscopy may enable screening and diagnosis of skin cancers noninvasively and in real-time, as an adjunct to biopsy and pathology. Current confocal point-scanning systems are large, complex, and expensive. A confocal line-scanning microscope, utilizing a of linear array detector can be simpler, smaller, less expensive, and may accelerate the translation of confocal microscopy in clinical and surgical dermatology. A line scanner may be implemented with a divided-pupil, half used for transmission and half for detection, or with a full-pupil using a beamsplitter. The premise is that a confocal line-scanner with either a divided-pupil or a full-pupil will provide high resolution and optical sectioning that would be competitive to that of the standard confocal point-scanner. We have developed a confocal line-scanner that combines both divided-pupil and full-pupil configurations. This combined-pupil prototype is being evaluated to determine the advantages and limitations of each configuration for imaging skin, and comparison of performance to that of commercially available standard confocal point-scanning microscopes. With the combined configuration, experimental evaluation of line spread functions (LSFs), contrast, signal-to-noise ratio, and imaging performance is in progress under identical optical and skin conditions. Experimental comparisons between divided-pupil and full-pupil LSFs will be used to determine imaging performance. Both results will be compared to theoretical calculations using our previously reported Fourier analysis model and to the confocal point spread function (PSF). These results may lead to a simpler class of confocal reflectance scanning microscopes for clinical and surgical dermatology.

  16. 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

    NASA Astrophysics Data System (ADS)

    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

  17. 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

    NASA Astrophysics Data System (ADS)

    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

  18. Theoretical study of carbon-based tips for scanning tunnelling microscopy

    NASA Astrophysics Data System (ADS)

    González, C.; Abad, E.; Dappe, Y. J.; Cuevas, J. C.

    2016-03-01

    Motivated by recent experiments, we present here a detailed theoretical analysis of the use of carbon-based conductive tips in scanning tunnelling microscopy. In particular, we employ ab initio methods based on density functional theory to explore a graphitic, an amorphous carbon and two diamond-like tips for imaging with a scanning tunnelling microscope (STM), and we compare them with standard metallic tips made of gold and tungsten. We investigate the performance of these tips in terms of the corrugation of the STM images acquired when scanning a single graphene sheet. Moreover, we analyse the impact of the tip-sample distance and show that it plays a fundamental role in the resolution and symmetry of the STM images. We also explore in depth how the adsorption of single atoms and molecules in the tip apexes modifies the STM images and demonstrate that, in general, it leads to an improved image resolution. The ensemble of our results provides strong evidence that carbon-based tips can significantly improve the resolution of STM images, as compared to more standard metallic tips, which may open a new line of research in scanning tunnelling microscopy.

  19. Theoretical study of carbon-based tips for scanning tunnelling microscopy.

    PubMed

    González, C; Abad, E; Dappe, Y J; Cuevas, J C

    2016-03-11

    Motivated by recent experiments, we present here a detailed theoretical analysis of the use of carbon-based conductive tips in scanning tunnelling microscopy. In particular, we employ ab initio methods based on density functional theory to explore a graphitic, an amorphous carbon and two diamond-like tips for imaging with a scanning tunnelling microscope (STM), and we compare them with standard metallic tips made of gold and tungsten. We investigate the performance of these tips in terms of the corrugation of the STM images acquired when scanning a single graphene sheet. Moreover, we analyse the impact of the tip-sample distance and show that it plays a fundamental role in the resolution and symmetry of the STM images. We also explore in depth how the adsorption of single atoms and molecules in the tip apexes modifies the STM images and demonstrate that, in general, it leads to an improved image resolution. The ensemble of our results provides strong evidence that carbon-based tips can significantly improve the resolution of STM images, as compared to more standard metallic tips, which may open a new line of research in scanning tunnelling microscopy. PMID:26861537

  20. Theoretical study of carbon-based tips for scanning tunnelling microscopy.

    PubMed

    González, C; Abad, E; Dappe, Y J; Cuevas, J C

    2016-03-11

    Motivated by recent experiments, we present here a detailed theoretical analysis of the use of carbon-based conductive tips in scanning tunnelling microscopy. In particular, we employ ab initio methods based on density functional theory to explore a graphitic, an amorphous carbon and two diamond-like tips for imaging with a scanning tunnelling microscope (STM), and we compare them with standard metallic tips made of gold and tungsten. We investigate the performance of these tips in terms of the corrugation of the STM images acquired when scanning a single graphene sheet. Moreover, we analyse the impact of the tip-sample distance and show that it plays a fundamental role in the resolution and symmetry of the STM images. We also explore in depth how the adsorption of single atoms and molecules in the tip apexes modifies the STM images and demonstrate that, in general, it leads to an improved image resolution. The ensemble of our results provides strong evidence that carbon-based tips can significantly improve the resolution of STM images, as compared to more standard metallic tips, which may open a new line of research in scanning tunnelling microscopy.

  1. Scanning probe microscope simulator for the assessment of noise in scanning probe microscopy controllers

    SciTech Connect

    Wutscher, T.; Niebauer, J.; Giessibl, F. J.

    2013-07-15

    We present an electronic circuit that allows to calibrate and troubleshoot scanning probe microscopy (SPM) controllers with respect to their noise performance. The control signal in an SPM is typically highly nonlinear—the tunneling current in scanning tunneling microscopy (STM) varies exponentially with distance. The exponential current-versus-voltage characteristics of diodes allow to model the current dependence in STM. Additional inputs allow to simulate the effects of external perturbations and the reactions of the control electronics. We characterized the noise performance of the feedback controller using the apparent topography roughness of recorded images. For a comparison of different STM controllers, an optimal gain parameter was determined by exploring settling times through a rectangular perturbation signal. We used the circuit to directly compare the performance of two types of SPM controllers used in our laboratory.

  2. Integration of a high-NA light microscope in a scanning electron microscope.

    PubMed

    Zonnevylle, A C; Van Tol, R F C; Liv, N; Narvaez, A C; Effting, A P J; Kruit, P; Hoogenboom, J P

    2013-10-01

    We present an integrated light-electron microscope in which an inverted high-NA objective lens is positioned inside a scanning electron microscope (SEM). The SEM objective lens and the light objective lens have a common axis and focal plane, allowing high-resolution optical microscopy and scanning electron microscopy on the same area of a sample simultaneously. Components for light illumination and detection can be mounted outside the vacuum, enabling flexibility in the construction of the light microscope. The light objective lens can be positioned underneath the SEM objective lens during operation for sub-10 μm alignment of the fields of view of the light and electron microscopes. We demonstrate in situ epifluorescence microscopy in the SEM with a numerical aperture of 1.4 using vacuum-compatible immersion oil. For a 40-nm-diameter fluorescent polymer nanoparticle, an intensity profile with a FWHM of 380 nm is measured whereas the SEM performance is uncompromised. The integrated instrument may offer new possibilities for correlative light and electron microscopy in the life sciences as well as in physics and chemistry.

  3. Plasma etching of superconducting Niobium tips for scanning tunneling microscopy

    SciTech Connect

    Roychowdhury, A.; Dana, R.; Dreyer, M.; Anderson, J. R.; Lobb, C. J.; Wellstood, F. C.

    2014-07-07

    We have developed a reproducible technique for the fabrication of sharp superconducting Nb tips for scanning tunneling microscopy (STM) and scanning tunneling spectroscopy. Sections of Nb wire with 250 μm diameter are dry etched in an SF₆ plasma in a Reactive Ion Etcher. The gas pressure, etching time, and applied power are chosen to control the ratio of isotropic to anisotropic etch rates and produce the desired tip shape. The resulting tips are atomically sharp, with radii of less than 100 nm, mechanically stable, and superconducting. They generate good STM images and spectroscopy on single crystal samples of Au(111), Au(100), and Nb(100), as well as a doped topological insulator Bi₂Se₃ at temperatures ranging from 30 mK to 9 K.

  4. A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans.

    PubMed

    Meier, Tobias; Förste, Alexander; Tavassolizadeh, Ali; Rott, Karsten; Meyners, Dirk; Gröger, Roland; Reiss, Günter; Quandt, Eckhard; Schimmel, Thomas; Hölscher, Hendrik

    2015-01-01

    We describe an atomic force microscope (AFM) for the characterization of self-sensing tunneling magnetoresistive (TMR) cantilevers. Furthermore, we achieve a large scan-range with a nested scanner design of two independent piezo scanners: a small high resolution scanner with a scan range of 5 × 5 × 5 μm(3) is mounted on a large-area scanner with a scan range of 800 × 800 × 35 μm(3). In order to characterize TMR sensors on AFM cantilevers as deflection sensors, the AFM is equipped with a laser beam deflection setup to measure the deflection of the cantilevers independently. The instrument is based on a commercial AFM controller and capable to perform large-area scanning directly without stitching of images. Images obtained on different samples such as calibration standard, optical grating, EPROM chip, self-assembled monolayers and atomic step-edges of gold demonstrate the high stability of the nested scanner design and the performance of self-sensing TMR cantilevers.

  5. A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

    PubMed Central

    Förste, Alexander; Tavassolizadeh, Ali; Rott, Karsten; Meyners, Dirk; Gröger, Roland; Reiss, Günter; Quandt, Eckhard; Schimmel, Thomas; Hölscher, Hendrik

    2015-01-01

    Summary We describe an atomic force microscope (AFM) for the characterization of self-sensing tunneling magnetoresistive (TMR) cantilevers. Furthermore, we achieve a large scan-range with a nested scanner design of two independent piezo scanners: a small high resolution scanner with a scan range of 5 × 5 × 5 μm3 is mounted on a large-area scanner with a scan range of 800 × 800 × 35 μm3. In order to characterize TMR sensors on AFM cantilevers as deflection sensors, the AFM is equipped with a laser beam deflection setup to measure the deflection of the cantilevers independently. The instrument is based on a commercial AFM controller and capable to perform large-area scanning directly without stitching of images. Images obtained on different samples such as calibration standard, optical grating, EPROM chip, self-assembled monolayers and atomic step-edges of gold demonstrate the high stability of the nested scanner design and the performance of self-sensing TMR cantilevers. PMID:25821686

  6. Dynamic-scanning-electron-microscope study of friction and wear

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Buckley, D. H.

    1974-01-01

    A friction and wear apparatus was built into a real time scanning electron microscope (SEM). The apparatus and SEM comprise a system which provides the capability of performing dynamic friction and wear experiments in situ. When the system is used in conjunction with dispersive X-ray analysis, a wide range of information on the wearing process can be obtained. The type of wear and variation with speed, load, and time can be investigated. The source, size, and distribution of wear particles can be determined and metallic transferal observed. Some typical results obtained with aluminum, copper, and iron specimens are given.

  7. Characteristics of different frequency ranges in scanning electron microscope images

    SciTech Connect

    Sim, K. S. Nia, M. E.; Tan, T. L.; Tso, C. P.; Ee, C. S.

    2015-07-22

    We demonstrate a new approach to characterize the frequency range in general scanning electron microscope (SEM) images. First, pure frequency images are generated from low frequency to high frequency, and then, the magnification of each type of frequency image is implemented. By comparing the edge percentage of the SEM image to the self-generated frequency images, we can define the frequency ranges of the SEM images. Characterization of frequency ranges of SEM images benefits further processing and analysis of those SEM images, such as in noise filtering and contrast enhancement.

  8. Microcircuit failure analysis using the SEM. [Scanning Electron Microscopes

    NASA Technical Reports Server (NTRS)

    Nicolas, D. P.

    1974-01-01

    The scanning electron microscope adds a new dimension to the knowledge that can be obtained from a failed microcircuit. When used with conventional techniques, SEM assists and clarifies the analysis, but it does not replace light microscopy. The most advantageous features for microcircuit analysis are long working distances and great depth of field. Manufacturer related failure modes of microcircuits are metallization defects, poor bonding, surface and particle contamination, and design and fabrication faults. User related failure modes are caused by abuse, such as overstress. The Physics of Failure Procedure followed by the Astrionics Laboratory in failure analysis is described, which is designed to obtain maximum information available from each step.

  9. Scanning Hall Probe Microscope and Imaging of Vortex Penetration into Nb

    NASA Astrophysics Data System (ADS)

    Bove, A.; Kundtz, N.; Chang, A. M.; Gusiatnikov, V.; Lichtenberger, Art

    2006-03-01

    We report on the construction of a scanning Hall probe microscope with 100 nm lateral resolution and a large scan range, which exceeds 40 μm at 4.2 K. The microscope is based on the beetle design and operates between room temperature and 1.5 K. The DSP-based control electronics achieves a high (100 kHz) sampling rate and a low noise. The system is capable of simultaneous tunneling and Hall signal acquisition. The Hall sensor for measuring local magnetic fields is fabricated on a GaAs heterostructure through standard EBL and wet etching. It has an active area of 300 nm x 300 nm and a sensistivity of 0.2 φ/Gauss. We will present (1) a description of the microscope, and (2) progress on imaging the penetration of vortices and the growth of vortex dendritic patterns into thin Nb films. Altshuler E. et al., Rev. Mod. Phys.76, 471 (April 2004) Hallen H. D. et al., Solid State Commumications 99 (9), 651-654 (SEP 1996).

  10. Scanning Acoustic Microscope of 3D-Interconnect

    NASA Astrophysics Data System (ADS)

    Wai Kong, Lay; Diebold, A. C.; Rudack, A.; Arkalgud, S.

    2009-09-01

    The College of Nanoscale Science and Engineering of the University at Albany in collaboration with International SEMATECH is investigating the use of Scanning Acoustic Microscope (SAM) for analyzing 3D Interconnects. SAM is a non-destructive metrology technique which utilizes high frequency ultrasound to generate a microscopic image of the internal parts of a specimen. The goal of this project is to develop microscopic techniques for evaluating Through-Silicon Vias (TSVs) for 3D-Interconnects. Preliminary data shows voids and other defects in the interface between bonded wafers as shown in Figure 1. Our SAM laboratory system operates at 230 MHz and has a spatial resolution of 5-10 μm and focal length of 5.9 mm on a silicon wafer. The spatial resolution and sampling depth depend on the ultrasonic frequency, sound velocity, focal length and diameter of piezoelectric crystal. Typically, the silicon wafers have a thickness of 775 μm before they are bonded. Our initial work is focused on blanket wafers in order to develop the bonding process. The next step is to bond wafers with test die where the patterning obscures the interface. This paper will discuss the limitations of SAM and compare it to infrared microscopy which is another important imaging capability for 3D Interconnect. We also discuss the current status of research into more advanced acoustic microscopy methods and how this might impact 3D Interconnect imaging.

  11. Monte Carlo simulation of topographic contrast in scanning ion microscope.

    PubMed

    Ohya, Kaoru; Ishitani, Tohru

    2004-01-01

    Topographic contrast of secondary-electron (SE) images in a scanning ion microscope (SIM) using a focused gallium (Ga) ion beam is investigated by Monte Carlo simulation. The SE yield of heavy materials, in particular, due to the impact of 30 keV Ga ions increases much faster than for the impact of electrons at < or =10 keV as a function of the angle of incidence of the primary beam. This indicates the topographic contrast for heavy materials is clearer in a SIM image than in a scanning electron microscope (SEM) image; for light materials both contrasts are similar to each other. Semicircular rods with different radii and steps with large heights and a small wall angle, made of Si and Au, are modeled for comparison with SE images in SEM. Line profiles of the SE intensity and pseudo-images constructed from the profiles reveal some differences of the topographic contrast between SIM and SEM. We discuss not only the incident-angle effect on the contrast, but also the effects of re-entrances of primary particles and SEs to the neighboring surface, the effect of a sharp edge on the sample surface, and the effects of pattern size and beam size.

  12. Charge ordering in stoichiometric FeTe: Scanning tunneling microscopy and spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Wei; Yin, Wei-Guo; Wang, Lili; He, Ke; Ma, Xucun; Xue, Qi-Kun; Chen, Xi

    2016-01-01

    We use scanning tunneling microscopy and spectroscopy to reveal a unique stripy charge order in a parent phase of iron-based superconductors in stoichiometric FeTe epitaxy films. The charge order has unusually the same—usually half—period as the spin order. We also found highly anisotropic electron band dispersions being large and little along the ferromagnetic (crystallographic b ) and antiferromagnetic (a ) directions, respectively. Our data suggest that the microscopic mechanism is likely of the Stoner type driven by interatomic Coulomb repulsion Vi j, and that Vi j and charge fluctuations, so far much neglected, are important to the understanding of iron-based superconductors.

  13. Controlled manipulation of gadolinium-coordinated supramolecules by low-temperature scanning tunneling microscopy.

    PubMed

    Urgel, José I; Ecija, David; Auwärter, Willi; Barth, Johannes V

    2014-03-12

    Coordination bonding between para-quarterphenyl-dicarbonitrile linkers and gadolinium on Ag(111) has been exploited to construct pentameric mononuclear supramolecules, consisting of a rare-earth center surrounded by five molecular linkers. By employing a scanning tunneling microscope tip, a manipulation protocol was developed to position individual pentamers on the surface. In addition, the tip was used to extract and replace individual linkers yielding tetrameric, pentameric, nonameric, and dodecameric metallosupramolecular arrangements. These results open new avenues toward advanced nanofabrication methods and rare-earth nanochemistry by combining the versatility of metal-ligand interactions and atomistic manipulation capabilities.

  14. Charge ordering in stoichiometric FeTe: Scanning tunneling microscopy and spectroscopy

    DOE PAGES

    Li, Wei; Yin, Wei -Guo; Wang, Lili; He, Ke; Ma, Xucun; Xue, Qi -Kun; Chen, Xi

    2016-01-04

    In this study, we use scanning tunneling microscopy and spectroscopy to reveal a unique stripy charge order in a parent phase of iron-based superconductors in stoichiometric FeTe epitaxy films. The charge order has unusually the same—usually half—period as the spin order. We also found highly anisotropic electron band dispersions being large and little along the ferromagnetic (crystallographic b) and antiferromagnetic (a) directions, respectively. Our data suggest that the microscopic mechanism is likely of the Stoner type driven by interatomic Coulomb repulsion Vij, and that Vij and charge fluctuations, so far much neglected, are important to the understanding of iron-based superconductors.

  15. Molecular Photography in the Undergraduate Laboratory: Identification of Functional Groups Using Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Giancarlo, Leanna C.; Fang, Hongbin; Avila, Luis; Fine, Leonard W.; Flynn, George W.

    2000-01-01

    A scanning tunneling microscope (STM) investigation of bare graphite and 11-bromoundecanol adsorbed on graphite has been performed in the undergraduate physical chemistry laboratory at Columbia University. In addition to collecting substrate (surface) and adsorbate (molecule) images, students compare their experimental STM topographs with the shapes of the frontier molecular orbitals of a structurally similar brominated alcohol generated using the Spartan computation program. This investigation stresses the use of the STM as a "molecular camera" with which students can visualize large-scale molecular assemblies and identify chemically significant portions of the molecules. Further, it demonstrates an area where theoretical calculations can be coupled with experimental measurements in a unified setting.

  16. Ultra-Compact Multitip Scanning Probe Microscope with an Outer Diameter of 50 mm

    NASA Astrophysics Data System (ADS)

    Cherepanov, Vasily; Zubkov, Evgeny; Junker, Hubertus; Korte, Stefan; Blab, Marcus; Coenen, Peter; Voigtländer, Bert

    We present a multitip scanning tunneling microscope (STM) where four independent STM units are integrated on a diameter of 50 mm. The coarse positioning of the tips is done under the control of an optical microscope or an SEM in vacuum. The heart of this STM is a new type of piezoelectric coarse approach called Koala Drive which can have a diameter greater than 2.5 mm and a length smaller than 10 mm. Alternating movements of springs move a central tube which holds the STM tip or AFM sensor. This new operating principle provides a smooth travel sequence and avoids shaking which is intrinsically present for nanopositioners based on inertial motion with saw tooth driving signals. Inserting the Koala Drive in a piezo tube for xyz-scanning integrates a complete STM inside a 4 mm outer diameter piezo tube of <10 mm length. The use of the Koala Drive makes the scanning probe microscopy design ultra-compact and accordingly leads to a high mechanical stability. The drive is UHV, low temperature, and magnetic field compatible. The compactness of the Koala Drive allows building a four-tip STM as small as a single-tip STM with a drift of <0.2 nm/min and lowest resonance frequencies of 2.5 (xy) and 5.5 kHz (z). We present examples of the performance of the multitip STM designed using the Koala Drive.

  17. Spin-polarized scanning tunneling microscopy: breakthroughs and highlights.

    PubMed

    Bode, Matthias

    2012-01-01

    The principle of scanning tunneling microscopy, an imaging method with atomic resolution capability invented by Binnig and Rohrer in 1982, can be adapted for surface magnetism studies by using magnetic probe tips. The contrast mechanism of this so-called spin-polarized scanning tunneling microscopy, or SP-STM, relies on the tunneling magneto-resistance effect, i.e. the tip-sample distance as well as the differential conductance depend on the relative magnetic orientation of tip and sample. To illustrate the working principle and the unique capabilities of SP-STM, this compilation presents some key experiments which have been performed on various magnetic surfaces, such as the topological antiferromagnet Cr(001), a double-layer of Fe which exhibits a stripe- domain pattern with about 50 nm periodicity, and the Mn monolayer on W(110), where the combination of experiment and theory reveal an antiferromagnetic spin cycloid. Recent experimental results also demonstrate the suitability of SP-STM for studies of dynamic properties, such as the spin relaxation time of single magnetic nanostructures. PMID:22546192

  18. Chemical reactions on solid surfaces: Atomistic observations by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Madix, R. J.; Crew, W. W.; Guo, X.-C.

    1997-04-01

    A scanning tunneling microscope has been developed which allows manipulation and control of the surface as well as scanning tunneling microscopy without transfer of the crystal off the manipulator to the microscope. The microscope is of the 'Johnnie Walker' type and is lowered onto the crystal, which is itself housed in a versatile transfer carriage. In this fashion surfaces can be ion bombarded, chemically treated, etc. and examined by the microscope at temperatures ranging from 120-400 K with atomic resolution without change in surface temperature. With this microscope we have studied the reaction of carbon monoxide with oxygen on Cu(110). At an ambient pressure of 10 -4 Torr carbon monoxide reacts with the p(2 × 1) islands of oxygen at a measurable rate only at 400 K or above. Reaction is approximately 1000 times faster along the (001) direction of the oxide islands than along the (110) direction. Reaction does not occur internal to the island unless there are defects to initiate the reaction. At 400 K the oxide islands do not maintain an equilibrium shape or distribution when reacting with ambient carbon monoxide, though in the presence of a low pressure of oxygen they appear to do so. At 150 K the p(2 × 1) oxide islands are inert to reaction with carbon monoxide and, additionally, short CuO chains are also unreactive. Reaction between pre-adsorbed carbon monoxide and ambient oxygen is observed, implying that mobile oxygen atoms which have not yet formed surface-bound pseudomolecules, can react with adsorbed carbon monoxide.

  19. Nt_STM: A step forward in Scanning Tunneling Microscopy (STM) simulations

    NASA Astrophysics Data System (ADS)

    Magoga, Michaël; Archambault, Fabien; Cerdá, Jorge I.

    2012-06-01

    We present the Nt_STM software suite designed to help analysis and interpretation of Scanning Tunneling Microscope (STM) images, via the simulation of STM data under different tip and bias conditions and facilitating their comparison against the experimental ones. The Nt_STM package includes two components: (i) an intuitive and directive Graphical User Interface (GUI) designed to build a precise model of the STM set-up and analyze the simulation results and, (ii) a powerful simulation engine (GREEN) allowing an efficient, yet accurate, calculation of the tunneling current necessary to generate current or topographic images, I(V) spectra as well as various properties such as band structures, Local Density Of State (LDOS), etc. The Nt_STM package, at its current version 2.0, gives the opportunity to access parallel computation, a new collection of objects and new Extended Hückel parameters.

  20. Orbital Selectivity in Scanning Tunneling Microscopy: Distance-Dependent Tunneling Process Observed in Iron Nitride

    NASA Astrophysics Data System (ADS)

    Takahashi, Y.; Miyamachi, T.; Ienaga, K.; Kawamura, N.; Ernst, A.; Komori, F.

    2016-02-01

    In scanning tunneling microscopy, orbital selectivity of the tunneling process can make the topographic image dependent on a tip-surface distance. We have found reproducible dependence of the images on the distance for a monatomic layer of iron nitride formed on a Cu(001) surface. Observed atomic images systematically change between a regular dot array and a dimerized structure depending on the tip-surface distance, which turns out to be the only relevant parameter in the image variation. An accompanied change in the weight of Fe -3 d local density of states to a tunneling background was detected in d I /d V spectra. These have been attributed to a shift in surface orbitals detected by the tip from the d states to the s /p states with increasing the tip-surface distance, consistent with an orbital assignment from first-principles calculations.

  1. Imaging free carriers in electronic material using a scanning probe microscope: Scanning capacitance microscopy

    SciTech Connect

    Erickson, A.; Adderton, D.; Day, T.; Alvis, R.

    1996-12-31

    The development of methods electrical properties, which are suitable to directly yield the desired carrier distributions on a nanometer scale has greatly benefited from the development of scanning probe technology over the last decade. Scanning Probe Microscopes (SPMs) offer inherent two-dimensionality and have been shown to have applications ranging from Magnet force to electro-chemistry. We have used an SPM in contact mode to simultaneously measure topography (and therefore physical structure) and capacitance variations (due to an applied bias) of various electronic materials such as doped silicon, poly silicon, SiC, and III-V materials.

  2. Observation of cell dynamics by laser scanning Raman microscope

    NASA Astrophysics Data System (ADS)

    Hamada, Keisaku; Fujita, Katsumasa; Kobayashi, Minoru; Kawata, Satoshi

    2007-02-01

    We developed a Raman microscope using a slit-scanning technique for observation of biological samples. A sample was illuminated by a line-shaped laser light, and Raman spectra were measured at different points in the line simultaneously by a spectrometer equipped with a 2D detector. The parallel detection of the Raman spectra boosts the image acquisition rate, which enable us to observe a living biological sample with high temporal and spatial resolution. We also applied a noise reduction technique using singular value decomposition. We recorded motion of intracellular components of living HeLa cells as sequential Raman images in a spectral region between 600 - 3000 cm -1 with the temporal resolution of 3 minutes.

  3. A scanning acoustic microscope based on picosecond ultrasonics.

    PubMed

    Che, S; Guduru, P R; Nurmikko, A V; Maris, H J

    2015-02-01

    We report on the development of a new type of scanning acoustic microscope. We use a femtosecond light pulse to generate a short sound pulse, and then focus this sound onto the sample by means of a specially designed and microfabricated acoustic lens of radius a few microns. The sound travels to the sample through a thin layer of water. The sound reflected from the sample is collected by the lens and then passes through a monolithically integrated optical resonant cavity. The induced change in the properties of this cavity are measured using a time-delayed probe light pulse. We describe some of the challenges involved in the construction and operation of this high-precision metrology apparatus and present some preliminary results.

  4. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas A.; Magel, Gregory A.; Hartfield, Cheryl D.; Moore, Thomas M.; Fowlkes, Jason D.; Rack, Philip D.

    2012-07-15

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {mu}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  5. High-speed line scanning confocal microscope for biological imaging

    NASA Astrophysics Data System (ADS)

    Jung, Seung-Hwan; Kim, Chang-Keun; Ju, Sung-Bin; Cho, Yong-Jin; Jeong, Hyun-Woo; Kim, Beop-Min

    2007-02-01

    We constructed a high-speed laser line-scanning confocal microscope (LSCM) using He-Ne laser (633 nm), a line CCD camera, and an acousto-optic deflector (AOD). The line scanner consists of an AOD and a cylindrical lens, which create a line focus sweeping over the sample. The line scanner generates two-dimensional confocal images (512× 512 pixel image) up to 191 frames per second with no mechanically-moving parts. This system is configured as an inverted microscope for imaging biological organisms or tissues. Images of various biological samples were obtained including rabbit cornea, onion cells, mouse melanoma tumor cells (B16BL6), and human breast tumor cells (BT-20). The frame rate may be further improved up to over 700 frames per second when the image size is reduced (512×128 pixel image). This system may be useful for analyzing fast phenomena during biological and chemical interactions and for imaging 3D structures rapidly.

  6. Bulk electronic structure of metals resolved with scanning tunneling microscopy.

    PubMed

    Pascual, J I; Dick, A; Hansmann, M; Rust, H-P; Neugebauer, J; Horn, K

    2006-02-01

    We demonstrate that bulk band structure can have a strong influence in scanning tunneling microscopy measurements by resolving electronic interference patterns associated with scattering phenomena of bulk states at a metal surface and reconstructing the bulk band topology. Our data reveal that bulk information can be detected because states at the edge of the surface-projected bulk band have a predominant role on the scattering patterns. With the aid of density functional calculations, we associate this effect with an intrinsic increase in the projected density of states of edge states. This enhancement is characteristic of the three-dimensional bulk band curvature, a phenomenon analog to a van Hove singularity.

  7. Scanning tunneling microscopy of 3 to 5 semiconductors

    NASA Astrophysics Data System (ADS)

    Dow, John D.

    1994-06-01

    Scanning tunneling microscopy and theory were combined to create novel depressive quantum dots at room temperature on the (110) surfaces of InSb dots which merit further exploration as potential nanopixels for tiny-device lithography; develop a strained-layer superlattice model of high-temperature superconductivity; image, understand, and make models of single-atom-high steps on III-V surfaces; invent and exploit a new kind of spectroscopy of surface states of semiconductors, called tipology; and develop phenomenological models of a variety of surface phenomena.

  8. Imaging and modification of polymers by scanning tunneling and atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Albrecht, T. R.; Dovek, M. M.; Lang, C. A.; Grütter, P.; Quate, C. F.; Kuan, S. W. J.; Frank, C. W.; Pease, R. F. W.

    1988-08-01

    Direct imaging of ultrathin organic films on solid surfaces is important for a variety of reasons; in particular, the use of such films as ultrathin resists for nanometer scale fabrication and information recording requires that we understand their microstrucure. We have used the Langmuir-Blodgett technique to prepare monolayer and submonolayer films of poly(octadecylacrylate) (PODA) and poly(methylmethacrylate) (PMMA) on graphite substrates. Atomic scale images obtained with the scanning tunneling microscope (STM) and the atomic force microscope of the PODA films showed a variety of structures, including isolated narrow fibrils, parallel groups of fibrils, and an ordered structure consistent with the side chain crystallization expected with that material. The fibrils observed are interpreted as individual polymer chains or small bundles of parallel chains. Images of the PMMA samples show no ordered regions. By applying voltage pulses on the STM tip, we were able to locally modify and apparently cut through the PODA fibrils.

  9. Correlation-steered scanning for scanning probe microscopes to overcome thermal drift for ultra-long time scanning.

    PubMed

    Zhang, Liansheng; Long, Qian; Liu, Yongbin; Zhang, Jie; Feng, Zhihua

    2016-07-01

    The thermal effect is one of the most important factors that influence the accuracy of nanoscale measurement and the surface topography of samples in scanning probe microscopes (SPMs). We propose a method called correlation-steered scanning, which is capable of overcoming three-dimensional thermal drifts in real time for ultra-long time scanned images. The image is scanned band by band with overlapping parts between adjacent bands. The vertical drift can be considered as linear and can thus be eliminated together with the tilt of the sample by applying the flattening method. Each band is artificially divided into several blocks for conveniently calculating lateral drifts on the basis of the overlapping area of adjacent bands through digital image correlation. The calculated lateral drifts are compensated to steer the scanning of the subsequent blocks, thus ensuring that all bands are parallel to one another. Experimental results proved that images scanned by the proposed method exhibited less distortions than those obtained from the traditional raster scanning method. The nanoscale measurement results based on the image obtained by the proposed method also showed high accuracy, with an error of less than 1.5%. By scanning as many bands as needed, the correlation-steered scanning method can obtain a highly precise SPM image of an ultra-large area.

  10. Differentiating amino acid residues and side chain orientations in peptides using scanning tunneling microscopy.

    PubMed

    Claridge, Shelley A; Thomas, John C; Silverman, Miles A; Schwartz, Jeffrey J; Yang, Yanlian; Wang, Chen; Weiss, Paul S

    2013-12-11

    Single-molecule measurements of complex biological structures such as proteins are an attractive route for determining structures of the large number of important biomolecules that have proved refractory to analysis through standard techniques such as X-ray crystallography and nuclear magnetic resonance. We use a custom-built low-current scanning tunneling microscope to image peptide structures at the single-molecule scale in a model peptide that forms β sheets, a structural motif common in protein misfolding diseases. We successfully differentiate between histidine and alanine amino acid residues, and further differentiate side chain orientations in individual histidine residues, by correlating features in scanning tunneling microscope images with those in energy-optimized models. Beta sheets containing histidine residues are used as a model system due to the role histidine plays in transition metal binding associated with amyloid oligomerization in Alzheimer's and other diseases. Such measurements are a first step toward analyzing peptide and protein structures at the single-molecule level.

  11. Simulation and Characterization of a Miniaturized Scanning Electron Microscope

    NASA Technical Reports Server (NTRS)

    Gaskin, Jessica A.; Jerman, Gregory A.; Medley, Stephanie; Gregory, Don; Abbott, Terry O.; Sampson, Allen R.

    2011-01-01

    A miniaturized Scanning Electron Microscope (mSEM) for in-situ lunar investigations is being developed at NASA Marshall Space Flight Center with colleagues from the University of Alabama in Huntsville (UAH), Advanced Research Systems (ARS), the University of Tennessee in Knoxville (UTK) and Case Western Reserve University (CWRU). This effort focuses on the characterization of individual components of the mSEM and simulation of the complete system. SEMs can provide information on the size, shape, morphology and chemical composition of lunar regolith. Understanding these basic properties will allow us to better estimate the challenges associated with In-Situ Resource Utilization and to improve our basic science knowledge of the lunar surface (either precluding the need for sample return or allowing differentiation of unique samples to be returned to Earth.) The main components of the mSEM prototype includes: a cold field emission electron gun (CFEG), focusing lens, deflection/scanning system and backscatter electron detector. Of these, the electron gun development is of particular importance as it dictates much of the design of the remaining components. A CFEG was chosen for use with the lunar mSEM as its emission does not depend on heating of the tungsten emitter (lower power), it offers a long operation lifetime, is orders of magnitude brighter than tungsten hairpin guns, has a small source size and exhibits low beam energy spread.

  12. High performance feedback for fast scanning atomic force microscopes

    NASA Astrophysics Data System (ADS)

    Schitter, G.; Menold, P.; Knapp, H. F.; Allgöwer, F.; Stemmer, A.

    2001-08-01

    We identify the dynamics of an atomic force microscope (AFM) in order to design a feedback controller that enables faster image acquisition at reduced imaging error compared to the now generally employed proportional integral differential (PID) controllers. First, a force model for the tip-sample interaction in an AFM is used to show that the dynamic behavior of the cantilever working in contact mode can be neglected for control purposes due to the relatively small oscillation amplitude of the cantilever in response to a defined topography step. Consequently, the dynamic behavior of the AFM system can be reduced to the behavior of the piezoelectric scanner making the design of a model based controller for the AFM possible. Second, a black box identification of the scanner of a commercial AFM (Nanoscope IIIa, Digital Instruments) is performed using subspace methods. Identification yields a mathematical model of the scanner which allows us to design a new controller utilizing H∞ theory. Finally, this controller is implemented on an existing AFM and operated in contact mode. We demonstrate that such an H∞-controlled AFM system, while scanning at rates five times faster than conventional PID-controlled systems, operates with reduced measurement error and allows scanning at lower forces.

  13. Scanning Photoelectron Microscope (SPEM) with a zone plate generated microprobe

    SciTech Connect

    Ade, H.; Kirz, J.; Hulbert, S.; Johnson, E.; Anderson, E.; Kern, D. . Dept. of Physics; Brookhaven National Lab., Upton, NY; Lawrence Berkeley Lab., CA . Center for X-Ray Optics; International Business Machines Corp., Yorktown Heights, NY . Thomas J. Watson Research Center)

    1989-01-01

    We describe instrumentation of a scanning photoelectron microscope (SPEM), which we are presently developing and commissioning at the X1A beamline of the National Synchrotron Light Source (NSLS). This instrument is designed to use the Soft X-ray Undulator (SXU) at the NSLS as a high brightness source to illuminate a Fresnel zone plate, thus forming a finely focused probe, {le} 0.2{mu}m in size, on the specimen surface. A grating monochromator selects the photon energy in the 400-800 eV range with an energy resolution better than 1 eV. The expected flux in the focus is in the 5 {times} 10{sup 7} {minus} 10{sup 9} photons/s range. A single pass Cylindrical Mirror Analyzer (CMA) is used to record photoemission spectra, or to form an image within a fixed electron energy bandwidth as the specimen is mechanically scanned. As a first test, a 1000 mesh Au grid was successfully imaged with Au 4 f primary photoelectrons, achieving a resolution of about 1{mu}m. 10 refs., 5 figs., 1 tab.

  14. Manipulation and immobilization of alkane-coated gold nanocrystals using scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Rolandi, M.; Scott, K.; Wilson, E. G.; Meldrum, F. C.

    2001-02-01

    Colloidal nanoparticles, comprised of gold nanocrystals, of mean diameter 2.8 nm, coated with an insulating chemically stable self-assembled monolayer of dodecanethiol, have been prepared. Monolayers of nanoparticles have been physisorbed on highly oriented pyrolitic graphite, first by self-assembly, and second by assembly as Langmuir films and subsequent deposition. Nanoparticles have been self-assembled on gold, and immobilized by chemisorption, using decanedithiol during assembly as a linking molecule. Scanning tunneling microscope images of the monolayers are obtained. At high substrate-tip voltages, >0.6 V, the tip is able to climb above the nanoparticles. The tunneling is then a two-step event, tunneling from the substrate to the gold nanocrystal, and subsequently from the gold nanocrystal to the tip. At low voltage, 0.25 V, the Coulomb blockade prevents one extra electron occupying the gold nanocrystal. The tip cannot then climb above the nanoparticles. The theoretical threshold of the blockade is estimated from the nanoparticle size, and shown to be consistent with the observations. At low substrate-tip voltages, rastering of the tip sweeps the nanoparticles from the raster area (but not at high tip voltage). This result has not been described previously, and it is envisaged that it could be used to separate nanoparticles of differing size. However, immobilized isolated nanoparticles are not removed, but only pushed temporarily aside by the scanning tip.

  15. Synchrotron X-ray Enhanced Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Rose, Volker; Freeland, John

    2011-03-01

    Proper understanding of complex phenomena occurring in nanostructures requires tools with both the ability to resolve the nanometer scale as well as provide detailed information about chemical, electronic, and magnetic structure. Scanning tunneling microscopy (STM) achieves the requisite high spatial resolution; however, direct elemental determination is not easily accomplished. X-ray microscopies, on the other hand, provide elemental selectivity, but currently have spatial resolution only of tens of nanometers. We present a novel and radically different concept that employs detection of local synchrotron x-ray interactions utilizing a STM that provides spatial resolution, and x-ray absorption directly yields chemical, electronic, and magnetic sensitivity. If during tunneling the sample is simultaneously illuminated with monochromatic x-rays, characteristic absorption will arise. Electrons that are excited into unoccupied levels close to the Fermi level modulate the tunneling current giving rise to elemental contrast. This work was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract DE-AC02-06CH11357.

  16. Miniaturized Environmental Scanning Electron Microscope for In Situ Planetary Studies

    NASA Technical Reports Server (NTRS)

    Gaskin, Jessica; Abbott, Terry; Medley, Stephanie; Gregory, Don; Thaisen, Kevin; Taylor , Lawrence; Ramsey, Brian; Jerman, Gregory; Sampson, Allen; Harvey, Ralph

    2010-01-01

    The exploration of remote planetary surfaces calls for the advancement of low power, highly-miniaturized instrumentation. Instruments of this nature that are capable of multiple types of analyses will prove to be particularly useful as we prepare for human return to the moon, and as we continue to explore increasingly remote locations in our Solar System. To this end, our group has been developing a miniaturized Environmental-Scanning Electron Microscope (mESEM) capable of remote investigations of mineralogical samples through in-situ topographical and chemical analysis on a fine scale. The functioning of an SEM is well known: an electron beam is focused to nanometer-scale onto a given sample where resulting emissions such as backscattered and secondary electrons, X-rays, and visible light are registered. Raster scanning the primary electron beam across the sample then gives a fine-scale image of the surface topography (texture), crystalline structure and orientation, with accompanying elemental composition. The flexibility in the types of measurements the mESEM is capable of, makes it ideally suited for a variety of applications. The mESEM is appropriate for use on multiple planetary surfaces, and for a variety of mission goals (from science to non-destructive analysis to ISRU). We will identify potential applications and range of potential uses related to planetary exploration. Over the past few of years we have initiated fabrication and testing of a proof-of-concept assembly, consisting of a cold-field-emission electron gun and custom high-voltage power supply, electrostatic electron-beam focusing column, and scanning-imaging electronics plus backscatter detector. Current project status will be discussed. This effort is funded through the NASA Research Opportunities in Space and Earth Sciences - Planetary Instrument Definition and Development Program.

  17. Method and apparatus for differential spectroscopic atomic-imaging using scanning tunneling microscopy

    DOEpatents

    Kazmerski, Lawrence L.

    1990-01-01

    A Method and apparatus for differential spectroscopic atomic-imaging is disclosed for spatial resolution and imaging for display not only individual atoms on a sample surface, but also bonding and the specific atomic species in such bond. The apparatus includes a scanning tunneling microscope (STM) that is modified to include photon biasing, preferably a tuneable laser, modulating electronic surface biasing for the sample, and temperature biasing, preferably a vibration-free refrigerated sample mounting stage. Computer control and data processing and visual display components are also included. The method includes modulating the electronic bias voltage with and without selected photon wavelengths and frequency biasing under a stabilizing (usually cold) bias temperature to detect bonding and specific atomic species in the bonds as the STM rasters the sample. This data is processed along with atomic spatial topography data obtained from the STM raster scan to create a real-time visual image of the atoms on the sample surface.

  18. Murine macrophage-lymphocyte interactions: scanning electron microscopic study.

    PubMed Central

    Albrecht, R M; Hinsdill, R D; Sandok, P L; Horowitz, S D

    1978-01-01

    Light and scanning electron microscopic observations revealed murine macrophage-lymphocyte interactions involving the initial contact of peritoneal, spleen, or thymus lymphocytes with peritoneal macrophage processes or microprocesses followed by clustering of lymphocytes over the central nuclear area of the macrophages. Lymphocyte-lymphocyte clustering was not observed in the absence of macrophages. Attachment and subsequent clustering appeared not to require the presence of serum or antigen; the attachment of allogeneic or xenogeneic lymphocytes was comparable to that seen in the syngeneic system, but central clustering of these lymphocytes failed to occur. No attachment or clustering was observed when thymic lymphocytes were cultured with thymus derived fibroblasts rather than with peritoneal macrophages. Lymphocyte attachment to immune, antigen-activated, syngeneic macrophages occurred more rapidly than that to normal unstimulated syngeneic macrophages; however, lymphocytes attached to the "activated" macrophages appeared to be killed by a nonphagocytic mechanism. A similar increase in the rate of lymphocyte attachment to macrophages occurred in the presence of migration inhibitory factor. Subsequent lymphocyte clustering on macrophages was observed in the migration inhibitory factor-stimulated cultures. In addition, lymphocyte-macrophage interactions similar to those in vitro were observed to occur in vivo on intraperitoneally implanted cover slips. Images PMID:101458

  19. Semiautomatic classification of cementitious materials using scanning electron microscope images

    NASA Astrophysics Data System (ADS)

    Drumetz, Lucas; Mura, Mauro Dalla; Meulenyzer, Samuel; Lombard, Sébastien; Chanussot, Jocelyn

    2015-11-01

    Segmentation and classification are prolific research topics in the image processing community. These topics have been increasingly used in the context of analysis of cementitious materials on images acquired with a scanning electron microscope. Indeed, there is a need to be able to detect and to quantify the materials present in a cement paste in order to follow the chemical reactions occurring in the material even days after the solidification. We propose a new approach for segmentation and classification of cementitious materials based on the denoising of the data with a block-matching three-dimensional (3-D) algorithm, binary partition tree (BPT) segmentation, support vector machines (SVM) classification, and interactivity with the user. The BPT provides a hierarchical representation of the spatial regions of the data, allowing a segmentation to be selected among the admissible partitions of the image. SVMs are used to obtain a classification map of the image. This approach combines state-of-the-art image processing tools with user interactivity to allow a better segmentation to be performed, or to help the classifier discriminate the classes better. We show that the proposed approach outperforms a previous method when applied to synthetic data and several real datasets coming from cement samples, both qualitatively with visual examination and quantitatively with the comparison of experimental results with theoretical ones.

  20. Scanning reflection ion microscopy in a helium ion microscope

    PubMed Central

    Vyvenko, Oleg F

    2015-01-01

    Summary 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. PMID:26171289

  1. A scanning acoustic microscope discriminates cancer cells in fluid

    NASA Astrophysics Data System (ADS)

    Miura, Katsutoshi; Yamamoto, Seiji

    2015-10-01

    Scanning acoustic microscopy (SAM) discriminates lesions in sections by assessing the speed of sound (SOS) or attenuation of sound (AOS) through tissues within a few minutes without staining; however, its clinical use in cytological diagnosis is unknown. We applied a thin layer preparation method to observe benign and malignant effusions using SAM. Although SAM is inferior in detecting nuclear features than light microscopy, it can differentiate malignant from benign cells using the higher SOS and AOS values and large irregular cell clusters that are typical features of carcinomas. Moreover, each single malignant cell exhibits characteristic cytoplasmic features such as a large size, irregular borders and secretory or cytoskeletal content. By adjusting the observation range, malignant cells are differentiated from benign cells easily using SAM. Subtle changes in the functional and structural heterogeneity of tumour cells were pursuable with a different digital data of SAM. SAM can be a useful tool for screening malignant cells in effusions before light microscopic observation. Higher AOS values in malignant cells compared with those of benign cells support the feasibility of a novel sonodynamic therapy for malignant effusions.

  2. Implementation of a cryogenic scanning microwave impedance microscope

    NASA Astrophysics Data System (ADS)

    Lai, Keji; Kundhikanjana, Worasom; Kelly, Michael; Shen, Zhi-Xun

    2009-03-01

    We have implemented a near-field scanning microwave impedance microscope in a variable temperature (2-300K) cryostat equipped with 9T magnet. Reflected microwave signals at 1GHz from a shielded cantilever probe were detected using room-temperature electronics. During the tip-sample approach, a small oscillating voltage was applied to the z-piezo and the modulated microwave signals were monitored to locate the sample surface. The approaching curve toward bulk dielectric materials can be quantitatively simulated by finite-element analysis. We have obtained the first low-T and high-B microwave images on a patterned silicon wafer with ion-implanted stripes. The results show clear impedance contrast in both the capacitive and loss channels. In particular, high-loss regions were seen between the heavily doped areas and the insulating substrate, allowing us to visualize the local conductivity variation. With this novel instrument, we expect to study electronic inhomogeneity in complex materials and explore local properties during phase transitions.

  3. Techniques For Mass Production Of Tunneling Electrodes

    NASA Technical Reports Server (NTRS)

    Kenny, Thomas W.; Podosek, Judith A.; Reynolds, Joseph K.; Rockstad, Howard K.; Vote, Erika C.; Kaiser, William J.

    1993-01-01

    Techniques for mass production of tunneling electrodes developed from silicon-micromachining, lithographic patterning, and related microfabrication processes. Tunneling electrodes named because electrons travel between them by quantum-mechanical tunneling; tunneling electrodes integral parts of tunneling transducer/sensors, which act in conjunction with feedback circuitry to stabilize tunneling currents by maintaining electrode separations of order of 10 Angstrom. Essential parts of scanning tunneling microscopes and related instruments, and used as force and position transducers in novel microscopic accelerometers and infrared detectors.

  4. Majorana fermion fingerprints in spin-polarised scanning tunnelling microscopy

    NASA Astrophysics Data System (ADS)

    Kotetes, Panagiotis; Mendler, Daniel; Heimes, Andreas; Schön, Gerd

    2015-11-01

    We calculate the spatially resolved tunnelling conductance of topological superconductors (TSCs) based on ferromagnetic chains, measured by means of spin-polarised scanning tunnelling microscopy (SPSTM). Our analysis reveals novel signatures of MFs arising from the interplay of their strongly anisotropic spin-polarisation and the magnetisation content of the tip. We focus on the deep Yu-Shiba-Rusinov (YSR) limit where only YSR bound states localised in the vicinity of the adatoms govern the low-energy as also the topological properties of the system. Under these conditions, we investigate the occurrence of zero/finite bias peaks (ZBPs/FBPs) for a single or two coupled TSC chains forming a Josephson junction. Each TSC can host up to two Majorana fermions (MFs) per edge if chiral symmetry is preserved. Here we retrieve the conductance for all the accessible configurations of the MF number of each chain. Our results illustrate innovative spin-polarisation-sensitive experimental routes for arresting the MFs by either restoring or splitting the ZBP in a predictable fashion via: (i) weakly breaking chiral symmetry, e.g. by the SPSTM tip itself or by an external Zeeman field and (ii) tuning the superconducting phase difference of the TSCs, which is encoded in the 4π-Josephson coupling of neighbouring MFs.

  5. Scanning Tunneling Spectroscopy in MgB{sub 2}

    SciTech Connect

    Karapetrov, G.; Iavarone, M.; Kwok, W. K.; Crabtree, G. W.; Hinks, D. G.

    2001-05-07

    We present scanning tunneling microscopy measurements of the surface of superconducting MgB{sub 2} with a critical temperature of 39 K. In zero magnetic field the conductance spectra can be analyzed in terms of the standard BCS theory with a smearing parameter {Gamma} . The value of the superconducting gap is 5 meV at 4.2 K, with no experimentally significant variation across the surface of the sample. The temperature dependence of the gap follows the BCS form, fully consistent with phonon-mediated superconductivity in this novel superconductor. The application of a magnetic field induces strong pair breaking as seen in the conductance spectra in fields up to 6 T.

  6. Cleaved thin-film probes for scanning tunneling microscopy.

    PubMed

    Siahaan, T; Kurnosikov, O; Barcones, B; Swagten, H J M; Koopmans, B

    2016-01-22

    We introduce an alternative type of probe for scanning tunneling microscopy (STM). Instead of using a needle-like tip made from a piece of metallic wire, a sharp-edged cleaved insulating substrate, which is initially covered by a thin conductive film, is used. The sharp tip is formed at the intersection of the two cleaved sides. Using this approach a variety of materials for STM probes can be used, and functionalization of STM probes is possible. The working principle of different probes made of metallic (Pt, Co, and CoB), indium-tin oxide, as well as Cu/Pt and Co/Pt multilayer films are demonstrated by STM imaging of clean Cu(001) and Cu(111) surfaces as well as the epitaxial Co clusters on Cu(111). PMID:26636763

  7. Scanning tunneling spectroscopy in MgB2.

    PubMed

    Karapetrov, G; Iavarone, M; Kwok, W K; Crabtree, G W; Hinks, D G

    2001-05-01

    We present scanning tunneling microscopy measurements of the surface of superconducting MgB2 with a critical temperature of 39 K. In zero magnetic field the conductance spectra can be analyzed in terms of the standard BCS theory with a smearing parameter gamma. The value of the superconducting gap is 5 meV at 4.2 K, with no experimentally significant variation across the surface of the sample. The temperature dependence of the gap follows the BCS form, fully consistent with phonon-mediated superconductivity in this novel superconductor. The application of a magnetic field induces strong pair breaking as seen in the conductance spectra in fields up to 6 T.

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

    PubMed Central

    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 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. PMID:27088134

  9. Nanotip electron gun for the scanning electron microscope.

    PubMed

    Vladár, András E; Radi, Zsolt; Postek, Michael T; Joy, David C

    2006-01-01

    Experimental nanotips have shown significant improvement in the resolution performance of a cold field emission scanning electron microscope (SEM). Nanotip electron sources are very sharp electron emitter tips used as a replacement for the conventional tungsten field emission (FE) electron sources. Nanotips offer higher brightness and smaller electron source size. An electron microscope equipped with a nanotip electron gun can provide images with higher spatial resolution and with better signal-to-noise ratio. This could present a considerable advantage over the current SEM electron gun technology if the tips are sufficiently long-lasting and stable for practical use. In this study, an older field-emission critical dimension (CD) SEM was used as an experimental test platform. Substitution of tungsten nanotips for the regular cathodes required modification of the electron gun circuitry and preparation of nanotips that properly fit the electron gun assembly. In addition, this work contains the results of the modeling and theoretical calculation of the electron gun performance for regular and nanotips, the preparation of the SEM including the design and assembly of a measuring system for essential instrument parameters, design and modification of the electron gun control electronics, development of a procedure for tip exchange, and tests of regular emitter, sharp emitter and nanotips. Nanotip fabrication and characterization procedures were also developed. Using a "sharp" tip as an intermediate to the nanotip clearly demonstrated an improvement in the performance of the test SEM. This and the results of the theoretical assessment gave support for the installation of the nanotips as the next step and pointed to potentially even better performance. Images taken with experimental nanotips showed a minimum two-fold improvement in resolution performance than the specification of the test SEM. The stability of the nanotip electron gun was excellent; the tip stayed useful

  10. The FAST module: an add-on unit for driving commercial scanning probe microscopes at video rate and beyond.

    PubMed

    Esch, Friedrich; Dri, Carlo; Spessot, Alessio; Africh, Cristina; Cautero, Giuseppe; Giuressi, Dario; Sergo, Rudi; Tommasini, Riccardo; Comelli, Giovanni

    2011-05-01

    We present the design and the performance of the FAST (Fast Acquisition of SPM Timeseries) module, an add-on instrument that can drive commercial scanning probe microscopes (SPM) at and beyond video rate image frequencies. In the design of this module, we adopted and integrated several technical solutions previously proposed by different groups in order to overcome the problems encountered when driving SPMs at high scanning frequencies. The fast probe motion control and signal acquisition are implemented in a way that is totally transparent to the existing control electronics, allowing the user to switch immediately and seamlessly to the fast scanning mode when imaging in the conventional slow mode. The unit provides a completely non-invasive, fast scanning upgrade to common SPM instruments that are not specifically designed for high speed scanning. To test its performance, we used this module to drive a commercial scanning tunneling microscope (STM) system in a quasi-constant height mode to frame rates of 100 Hz and above, demonstrating extremely stable and high resolution imaging capabilities. The module is extremely versatile and its application is not limited to STM setups but can, in principle, be generalized to any scanning probe instrument.

  11. Scanning Tunneling Spectroscopy on the GdSr2RuCu2O8 Compound

    NASA Astrophysics Data System (ADS)

    Bobba, F.; Giubileo, F.; Gombos, M.; Noce, C.; Vecchione, A.; Cucolo, A. M.; Roditchev, D.; Lamy, R.; Sacks, W.; Klein, J.

    Topographic and spectroscopic information on GdSr2RuCu2O8 sintered pellets have been obtained by a home built low temperature Scanning Tunneling Microscope (STM) operating at 4.2 K. The topographic image of the surface showed non homogeneous samples with grains of typical size of about 100 nm. In many locations studied, the Tunneling Spectroscopy reveals the presence of charging effects in the current-voltage characteristics over a voltage range up to 100 mV. Two types of charging effects are clearly distinguished: one corresponds to the reduction of the tunneling conductance around zero bias and is attributed to the Coulomb blockade, and another onw, a stepwise increasing of the current as a function of the bias voltage is identified as Coulomb staircase regime. Besides these spurious charging effects, the current-voltage characteristics often show a pronounced non-linearity around 4.0 mV. This non-linearity, disappearing above the critical temperature of the materials, is connected to the superconducting gap in the GdSr2RuCu2O8.

  12. Antenna-based ultrahigh vacuum microwave frequency scanning tunneling microscopy system.

    PubMed

    Giridharagopal, Rajiv; Zhang, Jun; Kelly, Kevin F

    2011-05-01

    The instrumental synthesis of high resolution scanning tunneling microscopy (STM) with the ability to measure differential capacitance with atomic scale resolution is highly desirable for fundamental metrology and for the study of novel physical characteristics. Microwave frequency radiation directed at the tip-sample junction in an STM system allows for such high-resolution differential capacitance information. This ability is particularly critical in ultrahigh vacuum environments, where the additional parameter space afforded by including a capacitance measurement would prove powerful. Here we describe the modifications made to a commercial scanning tunneling microscope to allow for broad microwave frequency alternating current scanning tunneling microscopy (ACSTM) in ultrahigh vacuum conditions using a relatively simple loop antenna and microwave difference frequency detection. The advantages of our system are twofold. First, the use of a removable antenna on a commercial STM prevents interference with other UHV processes while providing a simple method to retrofit any commercial UHV-STM with UHV-ACSTM capability. Second, mounting the microwave antenna on a translator allows for specific tuning of the system to replicate experimental conditions between samples, which is particularly critical in sensitive systems like organic thin films or single molecules where small changes in incident power can affect the results. Our innovation therefore provides a valuable approach to give nearly any commercial STM, be it an ambient or UHV system, the capability to measure atomic-scale microwave studies such as differential capacitance or even single molecule microwave response, and it ensures that experimental ACSTM conditions can be held constant between different samples. PMID:21639510

  13. Visualizing bone porosities using a tabletop scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, D.; DaPonte, J.; Broadbridge, C. C.; Daniel, D.; Alter, L.

    2010-04-01

    Pores are naturally occurring entities in bone. Changes in pore size and number are often associated with diseases such as Osteoporosis and even microgravity during spaceflight. Studying bone perforations may yield great insight into bone's material properties, including bone density and may contribute to identifying therapies to halt or potentially reverse bone loss. Current technologies used in this field include nuclear magnetic resonance, micro-computed tomography and the field emission scanning electron microscope (FE-SEM) 2, 5. However, limitations in each method limit further advancement. The objective of this study was to assess the effectiveness of using a new generation of analytical instruments, the TM-1000 tabletop, SEM with back-scatter electron (BSE) detector, to analyze cortical bone porosities. Hind limb unloaded and age-based controlled mouse femurs were extracted and tested in vitro for changes in pores on the periosteal surface. An important advantage of using the tabletop is the simplified sample preparation that excludes extra coatings, dehydration and fixation steps that are otherwise required for conventional SEM. For quantitative data, pores were treated as particles in order to use an analyze particles feature in the NIH ImageJ software. Several image-processing techniques for background smoothing, thresholding and filtering were employed to produce a binary image suitable for particle analysis. It was hypothesized that the unloaded bones would show an increase in pore area, as the lack of mechanical loading would affect bone-remodeling processes taking place in and around pores. Preliminary results suggest only a slight different in frequency but not in size of pores between unloaded and control femurs.

  14. Structural changes in a Schiff base molecular assembly initiated by scanning tunneling microscopy tip.

    PubMed

    Tomak, A; Bacaksiz, C; Mendirek, G; Sahin, H; Hur, D; Görgün, K; Senger, R T; Birer, Ö; Peeters, F M; Zareie, H M

    2016-08-19

    We report the controlled self-organization and switching of newly designed Schiff base (E)-4-((4-(phenylethynyl) benzylidene) amino) benzenethiol (EPBB) molecules on a Au (111) surface at room temperature. Scanning tunneling microscopy and spectroscopy (STM/STS) were used to image and analyze the conformational changes of the EPBB molecules. The conformational change of the molecules was induced by using the STM tip while increasing the tunneling current. The switching of a domain or island of molecules was shown to be induced by the STM tip during scanning. Unambiguous fingerprints of the switching mechanism were observed via STM/STS measurements. Surface-enhanced Raman scattering was employed, to control and identify quantitatively the switching mechanism of molecules in a monolayer. Density functional theory calculations were also performed in order to understand the microscopic details of the switching mechanism. These calculations revealed that the molecular switching behavior stemmed from the strong interaction of the EPBB molecules with the STM tip. Our approach to controlling intermolecular mechanics provides a path towards the bottom-up assembly of more sophisticated molecular machines. PMID:27378765

  15. Multilevel memristor effect in metal-semiconductor core-shell nanoparticles tested by scanning tunneling spectroscopy.

    PubMed

    Chakrabarti, Sudipto; Pal, Amlan J

    2015-06-01

    We have grown gold (Au) and copper-zinc-tin-sulfide (CZTS) nanocrystals and Au-CZTS core-shell nanostructures, with gold in the core and the semiconductor in the shell layer, through a high-temperature colloidal synthetic approach. Following usual characterization, we formed ultrathin layers of these in order to characterize the nanostructures in an ultrahigh-vacuum scanning tunneling microscope. Scanning tunneling spectroscopy of individual nanostructures showed the memristor effect or resistive switching from a low- to a high-conducting state upon application of a suitable voltage pulse. The Au-CZTS core-shell nanostructures also show a multilevel memristor effect with the nanostructures undergoing two transitions in conductance at two magnitudes of voltage pulse. We have studied the reproducibility, reversibility, and retentivity of the multilevel memristors. From the normalized density of states (NDOS), we infer that the memristor effect is correlated to a decrease in the transport gap of the nanostructures. We also infer that the memristor effect occurs in the nanostructures due to an increase in the density of available states upon application of a voltage pulse. PMID:25966930

  16. Multilevel memristor effect in metal-semiconductor core-shell nanoparticles tested by scanning tunneling spectroscopy.

    PubMed

    Chakrabarti, Sudipto; Pal, Amlan J

    2015-06-01

    We have grown gold (Au) and copper-zinc-tin-sulfide (CZTS) nanocrystals and Au-CZTS core-shell nanostructures, with gold in the core and the semiconductor in the shell layer, through a high-temperature colloidal synthetic approach. Following usual characterization, we formed ultrathin layers of these in order to characterize the nanostructures in an ultrahigh-vacuum scanning tunneling microscope. Scanning tunneling spectroscopy of individual nanostructures showed the memristor effect or resistive switching from a low- to a high-conducting state upon application of a suitable voltage pulse. The Au-CZTS core-shell nanostructures also show a multilevel memristor effect with the nanostructures undergoing two transitions in conductance at two magnitudes of voltage pulse. We have studied the reproducibility, reversibility, and retentivity of the multilevel memristors. From the normalized density of states (NDOS), we infer that the memristor effect is correlated to a decrease in the transport gap of the nanostructures. We also infer that the memristor effect occurs in the nanostructures due to an increase in the density of available states upon application of a voltage pulse.

  17. Scanning Tunneling Spectroscopy on InAs-GaSb Esaki Diode Nanowire Devices during Operation.

    PubMed

    Persson, Olof; Webb, James L; Dick, Kimberly A; Thelander, Claes; Mikkelsen, Anders; Timm, Rainer

    2015-06-10

    Using a scanning tunneling and atomic force microscope combined with in-vacuum atomic hydrogen cleaning we demonstrate stable scanning tunneling spectroscopy (STS) with nanoscale resolution on electrically active nanowire devices in the common lateral configuration. We use this method to map out the surface density of states on both the GaSb and InAs segments of GaSb-InAs Esaki diodes as well as the transition region between the two segments. Generally the surface shows small bandgaps centered around the Fermi level, which is attributed to a thin multielement surface layer, except in the diode transition region where we observe a sudden broadening of the bandgap. By applying a bias to the nanowire we find that the STS spectra shift according to the local nanoscale potential drop inside the wire. Importantly, this shows that we have a nanoscale probe with which we can infer both surface electronic structure and the local potential inside the nanowire and we can connect this information directly to the performance of the imaged device. PMID:25927249

  18. Structural changes in a Schiff base molecular assembly initiated by scanning tunneling microscopy tip

    NASA Astrophysics Data System (ADS)

    Tomak, A.; Bacaksiz, C.; Mendirek, G.; Sahin, H.; Hur, D.; Görgün, K.; Senger, R. T.; Birer, Ö.; Peeters, F. M.; Zareie, H. M.

    2016-08-01

    We report the controlled self-organization and switching of newly designed Schiff base (E)-4-((4-(phenylethynyl) benzylidene) amino) benzenethiol (EPBB) molecules on a Au (111) surface at room temperature. Scanning tunneling microscopy and spectroscopy (STM/STS) were used to image and analyze the conformational changes of the EPBB molecules. The conformational change of the molecules was induced by using the STM tip while increasing the tunneling current. The switching of a domain or island of molecules was shown to be induced by the STM tip during scanning. Unambiguous fingerprints of the switching mechanism were observed via STM/STS measurements. Surface-enhanced Raman scattering was employed, to control and identify quantitatively the switching mechanism of molecules in a monolayer. Density functional theory calculations were also performed in order to understand the microscopic details of the switching mechanism. These calculations revealed that the molecular switching behavior stemmed from the strong interaction of the EPBB molecules with the STM tip. Our approach to controlling intermolecular mechanics provides a path towards the bottom-up assembly of more sophisticated molecular machines.

  19. How the vortex lattice of a superconductor becomes disordered: a study by scanning tunneling spectroscopy.

    PubMed

    Zehetmayer, M

    2015-01-01

    Order-disorder transitions take place in many physical systems, but observing them in detail in real materials is difficult. In two- or quasi-two-dimensional systems, the transition has been studied by computer simulations and experimentally in electron sheets, dusty plasmas, colloidal and other systems. Here I show the different stages of defect formation in the vortex lattice of a superconductor while it undergoes an order-disorder transition by presenting real-space images of the lattice from scanning tunneling spectroscopy. When the system evolves from the ordered to the disordered state, the predominant kind of defect changes from dislocation pairs to single dislocations, and finally to defect clusters forming grain boundaries. Correlation functions indicate a hexatic-like state preceding the disordered state. The transition in the microscopic vortex distribution is mirrored by the well-known spectacular second peak effect observed in the macroscopic current density of the superconductor.

  20. Scanning tunneling microscopy/spectroscopy on perovskite oxide thin films deposited in situ.

    PubMed

    Hitosugi, Taro; Shimizu, Ryota; Ohsawa, Takeo; Iwaya, Katsuya

    2014-10-01

    Complex oxide surfaces and interfaces, consisting of two or more cations and oxygen anions, have attracted a great deal of attention because their properties are crucial factors in the performance of catalysts, fuel cells, and Li-ion batteries. However, atomic-scale investigations of these oxide surfaces have been hindered because of the difficulties in surface preparation. Here, we demonstrate atomic-scale surface studies of complex perovskite oxides and the initial growth processes in oxide epitaxial films deposited on (✓13 × ✓13)-R33.7° reconstructed SrTiO3 (001) substrates using a scanning tunneling microscope integrated with a pulsed laser deposition system. The atomically ordered, reconstructed SrTiO3 (001) surface is stable under the typical conditions necessary for the growth of oxide thin films, and hence is considered suitable for the study of the initial growth processes in oxide films. The atomic-scale microscopic/spectroscopic characterizations performed here shed light on the microscopic origin of electronic properties observed in complex oxides and their heterostructures.

  1. Quantitative materials contrast at high spatial resolution with a novel near-field scanning microwave microscope

    NASA Astrophysics Data System (ADS)

    Imtiaz, Atif

    A novel Near-Field Scanning Microwave Microscope (NSMM) has been developed where a Scanning Tunneling Microscope (STM) is used for tip-to-sample distance control. The technique is non-contact and non-destructive. The same tip is used for both STM and NSMM, and STM helps maintain the tip-to-sample distance at a nominal height of 1 nm. Due to this very small tip-to-sample separation, the contribution to the microwave signals due to evanescent (non-propagating) waves cannot be ignored. I describe different evanescent wave models developed so far to understand the complex tip-to-sample interaction at microwave frequencies. Propagating wave models are also discussed, since they are still required to understand some aspects of the tip-to-sample interaction. Numerical modeling is also discussed for these problems. I demonstrate the sensitivity of this novel microscope to materials property contrast. The materials contrast is shown in spatial variations on the surface of metal thin films, Boron-doped Semiconductor and Colossal Magneto-Resistive (CMR) thin films. The height dependence of the contrast shows sensitivity to nano-meter sized features when the tip-to-sample separation is below 100 nm. By adding a cone of height 4 nm to the tip, I am able to explain a 300 kHz deviation observed in the frequency shift signal, when tip-to-sample separation is less than 10 nm. In the absence of the cone, the frequency shift signal should continue to show the logarithmic behavior as a function of height. I demonstrate sub-micron spatial resolution with this novel microscope, both in tip-to-sample capacitance Cx and materials contrast in sheet resistance Rx. The spatial resolution in Cx is demonstrated to be at-least 2.5 nm on CMR thin films. The spatial resolution in Rx is shown to be sub-micron by measuring a variably Boron-doped Silicon sample which was prepared using the Focus Ion Beam (FIB) technique.

  2. Electromagnetic model for near-field microwave microscope with atomic resolution: Determination of tunnel junction impedance

    SciTech Connect

    Reznik, Alexander N.

    2014-08-25

    An electrodynamic model is proposed for the tunneling microwave microscope with subnanometer space resolution as developed by Lee et al. [Appl. Phys. Lett. 97, 183111 (2010)]. Tip-sample impedance Z{sub a} was introduced and studied in the tunneling and non-tunneling regimes. At tunneling breakdown, the microwave current between probe and sample flows along two parallel channels characterized by impedances Z{sub p} and Z{sub t} that add up to form overall impedance Z{sub a}. Quantity Z{sub p} is the capacitive impedance determined by the near field of the probe and Z{sub t} is the impedance of the tunnel junction. By taking into account the distance dependences of effective tip radius r{sub 0}(z) and tunnel resistance R{sub t}(z) = Re[Z{sub t}(z)], we were able to explain the experimentally observed dependences of resonance frequency f{sub r}(z) and quality factor Q{sub L}(z) of the microscope. The obtained microwave resistance R{sub t}(z) and direct current tunnel resistance R{sub t}{sup dc}(z) exhibit qualitatively similar behavior, although being largely different in both magnitude and the characteristic scale of height dependence. Interpretation of the microwave images of the atomic structure of test samples proved possible by taking into account the inductive component of tunnel impedance ImZ{sub t} = ωL{sub t}. Relation ωL{sub t}/R{sub t} ≈ 0.235 was obtained.

  3. Scanning differential polarization microscope: Its use to image linear and circular differential scattering

    SciTech Connect

    Mickols, W.; Maestre, M.F.

    1988-06-01

    A differential polarization microscope that couples the sensitivity of single-beam measurement of circular dichroism and circular differential scattering with the simultaneous measurement of linear dichroism and linear differential scattering has been developed. The microscope uses a scanning microscope stage and single-point illumination to give the very shallow depth of field found in confocal microscopy. This microscope can operate in the confocal mode as well as in the near confocal condition that can allow one to program the coherence and spatial resolution of the microscope. This microscope has been used to study the change in the structure of chromatin during the development of sperm in Drosophila.

  4. Single-molecule conductance measurement of self-assembled organic monolayers using scanning tunneling spectroscopy in combination with statistics analysis

    NASA Astrophysics Data System (ADS)

    Zhang, Yumei; Dou, Chengfu; Wang, Yin

    2011-05-01

    Based on ambient atmosphere scanning tunneling microscope (STM) technique, scanning tunneling spectroscopy (STS) combined with statistics analysis was developed to investigate the single-molecule conductance of various kinds of molecules which were self-assembled on the Au (1 1 1). Conductance histograms obtained from current-voltage curves revealed well-defined peaks at integer multiples of a fundamental conductance and were used to identify the conductance of a single molecule. The conductances of saturated molecules like 1,8-octanedithol and hexanethiocyanate were found to be 0.072 × 10 -4G 0 and 0.06 × 10 -4G 0 respectively and 0.23 × 10 -4G 0 and 0.13 × 10 -4G 0 for unsaturated molecules like 5,5'-dithiol- 2,2',5',2″-terthiophene and 4,4'-dithio-tert(phenylene ethylene).

  5. Scanning tunneling microscopy of DNA-wrapped carbon nanotubes.

    PubMed

    Yarotski, Dzmitry A; Kilina, Svetlana V; Talin, A Alec; Tretiak, Sergei; Prezhdo, Oleg V; Balatsky, Alexander V; Taylor, Antoinette J

    2009-01-01

    We employ scanning tunneling microscopy (STM) to reveal the structure of DNA-carbon nanotube complexes with unprecedented spatial resolution and compare our experimental results to molecular dynamics simulations. STM images show strands of DNA wrapping around (6,5) nanotubes at approximately 63 degrees angle with a coiling period of 3.3 nm, in agreement with the theoretical predictions. In addition, we observe width modulations along the DNA molecule itself with characteristic lengths of 1.9 and 2.5 nm, which remain unexplained. In our modeling we use a helical coordinate system, which naturally accounts for tube chirality along with an orbital charge density distribution and allows us to simulate this hybrid system with the optimal pi-interaction between DNA bases and the nanotube. Our results provide novel insight into the self-assembling mechanisms of nanotube-DNA hybrids and can be used to guide the development of novel DNA-based nanotube separation and self-assembly methods, as well as drug delivery and cancer therapy techniques. PMID:19086808

  6. Scanning tunnelling microscopy observations of biomolecules on layered materials.

    PubMed

    Jungblut, H; Campbell, S A; Giersig, M; Müller, D J; Lewerenz, H J

    1992-01-01

    Scanning tunnelling microscopy (STM) has been performed on the reverse transcriptases of the human immunodeficiency virus (HIV-1) and the moloney murine leukaemia virus (MuLV). The biological molecules are adsorbed on n-type semiconducting MoTe2. The p66 (66 kD) subunit of the RT of HIV-1 is imaged by STM. Both STM and processed transmission electron microscopy (TEM) data show a spherical and horseshoe-like shape of external diameter ca. 65 A, depending on the angle of observation. The STM results show a larger diameter which is related to the curvature radius of the tip of the probing needle. The RTs of HIV-1 and MuLV exhibit a circular hole of ca. 20 A diameter in accordance with structure predictions and functioning considerations. The surface-molecule interaction is discussed in terms of the electronic properties of the semiconductor surface including the influence of small defect sites at the layered crystal surface. PMID:1285040

  7. Scanning Tunneling Microscopy and Spectroscopy of Iron-Based Superconductors

    NASA Astrophysics Data System (ADS)

    Hoffman, Jennifer

    2010-03-01

    Two decades after the discovery of high-Tc superconductivity in the cuprates, superconductivity was discovered up to 55, in a second family of materials: the iron-pnictides. This recent discovery has generated tremendous excitement for several reasons. First, there is hope that the iron-pnictides will finally provide the foil necessary to understand the enormous yet puzzling body of research on the cuprates. Second, reports of low anisotropy and strong vortex pinning in these new materials have spurred optimism that the iron-pnictides may finally lead to the widespread technological applications which have been elusive for cuprates. In this talk, I will present the first scanning tunneling spectroscopic imaging study of a single crystal iron-pnictide superconductor in high magnetic fields. We study optimally doped BaCo0.2Fe1.8As2 with Tc= 25.3,, finding a ˜6, superconducting gap with nanoscale inhomogeneity, which leads to an average reduced gap of 2δ/kBTc˜5.7. We further observe a static disordered vortex lattice at 9,, and demonstrate that vortices are pinned in the bulk of this material, a promising observation for practical application.

  8. Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials

    NASA Technical Reports Server (NTRS)

    Perez, Jose M.

    1996-01-01

    We present a summary of the research, citations of publications resulting from the research and abstracts of such publications. We have made no inventions in the performance of the work in this project. The main goals of the project were to set up a Chemical Vapor Deposition (CVD) diamond growth system attached to an UltraHigh Vacuum (UHV) atomic resolution Scanning Tunneling Microscopy (STM) system and carry out experiments aimed at studying the properties and growth of diamond films using atomic resolution UHV STM. We successfully achieved these goals. We observed, for the first time, the atomic structure of the surface of CVD grown epitaxial diamond (100) films using UHV STM. We studied the effects of atomic hydrogen on the CVD diamond growth process. We studied the electronic properties of the diamond (100) (2x1) surface, and the effect of alkali metal adsorbates such as Cs on the work function of this surface using UHV STM spectroscopy techniques. We also studied, using STM, new electronic materials such as carbon nanotubes and gold nanostructures. This work resulted in four publications in refereed scientific journals and five publications in refereed conference proceedings.

  9. Visualizing Topological Surface States using Scanning Tunneling Microscopy and Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yazdani, Ali

    2010-03-01

    Topological insulators are a new class of insulators in which a bulk gap for electronic excitations is generated by strong spin-orbit coupling. These novel materials are distinguished from ordinary insulators by the presence of gapless metallic boundary states, akin to the chiral edge modes in quantum Hall systems, but with unconventional spin textures. Angle resolved photoemission experiments and theoretical efforts have provided strong evidence for bulk topological insulators and their spin-chiral surface states in several Bi-based compounds. We have performed scanning tunneling microscopy and spectroscopic studies of topological surface states on a range of different compounds. I will describe how these experiments illustrate the importance of the spin-texture of these novel states on their scattering and quantum confinement. Experiments demonstrate that these states are protected from backscattering between opposite spin states due to their chiral spin textures. [1]. More recently, our studies were extended to determine the interplay between the influence of spin symmetry on scattering and the possibility of energy level quantization due to geometric confinement for topological surface states. [2] Work was done in collaboration with P. Roushan, J. Seo, H. Beidenkopf, Y.-S. Hor, C. Parker, D. Hsieh, D. Qian, and A. Richardella, M. Z. Hasan, R. Cava. Supported by ARO, ONR, and MRSEC through PCCM. [4pt] [1] P. Roushan et al. Nature 460, 1106 (2009). [0pt] [2] J. Seo et al. submitted (2009).

  10. Metal-silicene interaction studied by scanning tunneling microscopy.

    PubMed

    Li, Zhi; Feng, Haifeng; Zhuang, Jincheng; Pu, Na; Wang, Li; Xu, Xun; Hao, Weichang; Du, Yi

    2016-01-27

    Ag atoms have been deposited on 3  ×  3 silicene and  √3  ×  √3 silicene films by molecular beam epitaxy method in ultrahigh vacuum. Using scanning tunneling microscopy and Raman spectroscopy, we found that Ag atoms do not form chemical bonds with both 3  ×  3 silicene and  √3  ×  √3 silicene films, which is due to the chemically inert surface of silicene. On 3  ×  3 silicene films, Ag atoms mostly form into stable flat-top Ag islands. In contrast, Ag atoms form nanoclusters and glide on silicene films, suggesting a more inert nature. Raman spectroscopy suggests that there is more sp (2) hybridization in  √3  ×  √3 than in  √7  ×  √7/3  ×  3 silicene films.

  11. Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

    PubMed

    Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

    2015-02-01

    We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of <100 nm. In order to demonstrate the spatiotemporal magnetic imaging capability of this microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz. PMID:25725848

  12. Josephson scanning tunneling microscopy -- a local and direct probe of the superconducting order parameter

    SciTech Connect

    Kimura, Hikari; Dynes, Robert; Barber Jr., Richard. P.; Ono, S.; Ando, Y.

    2009-09-01

    Direct measurements of the superconducting superfluid on the surface of vacuum-cleaved Bi2Sr2CaCu2O8+delta (BSCCO) samples are reported. These measurements are accomplished via Josephson tunneling into the sample using a novel scanning tunneling microscope (STM) equipped with a superconducting tip. The spatial resolution of the STM of lateral distances less than the superconducting coherence length allows it to reveal local inhomogeneities in the pair wavefunction of the BSCCO. Instrument performance is demonstrated first with Josephson measurements of Pb films followed by the layered superconductor NbSe2. The relevant measurement parameter, the Josephson ICRN product, is discussed within the context of both BCS superconductors and the high transition temperature superconductors. The local relationship between the ICRN product and the quasiparticle density of states (DOS) gap are presented within the context of phase diagrams for BSCCO. Excessive current densities can be produced with these measurements and have been found to alter the local DOS in the BSCCO. Systematic studies of this effect were performed to determine the practical measurement limits for these experiments. Alternative methods for preparation of the BSCCO surface are also discussed.

  13. Energy gap distribution of HgBa{sub 2}CuO{sub 4+{delta}} investigated by scanning tunneling microscopy/spectroscopy

    SciTech Connect

    Jess, P.; Hubler, U.; Lang, H.P.

    1996-12-01

    The superconducting energy gap distribution of polycrystalline HgBa{sub 2}CuO{sub 4+{delta}} samples of differing oxygen doping levels (T{sub c} = 94 K and T{sub c} = 96 K) is determined by scanning tunneling spectroscopy (STS) using a low temperature scanning tunneling microscope (STM). From histograms of energy gap values the presence of two distinct energy gaps is inferred ({Delta}{sub 1}=8.5{+-}1.6 meV and {Delta}{sub 2}=15.1{+-}1.4meV). The authors attribute the different gaps to different crystallographic faces, implying a non-BCS electron-electron pairing mechanism.

  14. Scanning tunneling microscopy studies of mixed self-assembled monolayers

    NASA Astrophysics Data System (ADS)

    Raigoza, Annette Fernandez

    This thesis examines the formation of multicomponent self-assembled mono-layers (SAMs) on the Au(111) surface using scanning tunneling microscopy. Two methods, sequential adsorption and coadsorption, are used to create these mixed SAMs. In the sequential adsorption experiments, a clean Au(111)-on-mica sub-strate is exposed to the first molecular species and then this adsorbate-covered sample is exposed to the second molecular species. Alternately, in the coadsorption experiments, a gold surface is exposed to both adsorbates simultaneously. Exposing a coronene- or dithiocarbamate-covered surface to excess thiol in the vapor phase results in a drastic restructuring of the initial surface. This is primarily driven by the kinetics of the octanethiol monolayer formation process, but the extent to which this happens is dependent on the molecule-molecule and molecule-surface interactions of the adsorbate due to the initial coverage and order of the monolayer. An octanethiolate monolayer is also substantially modified when immersed in a solution containing dithiocarbamate (DTC). Defects in the octanethiol monolayer are prime sites for molecular exchange. A surplus of DTC in the solution drives substitution that can lead to the complete removal of thiol from the surface. When a Au(111) surface is exposed to solutions containing both octanethiol and dithiocarbamate (DTC), both molecular species compete for available ad- sorption sites. At equal octanethiol-to-DTC ratios, molecular exchange hinders octanethiol monolayer formation. Higher octanethiol concentration in solution results in the incorporation of thiol into the resulting monolayer, with a strong dependence on the chain length of the DTC molecules.

  15. Scanning magnetic tunnel junction (MTJ) microscopy: High-resolution magnetic imaging of geologic samples

    NASA Astrophysics Data System (ADS)

    Lascu, I.; Harrison, R. J.

    2014-12-01

    We describe a Micromagnetics, Inc. magnetic tunnel junction (MTJ) scanning microscope developed for the University of Cambridge Nanopaleomagnetism Lab. The MTJ sensor used contains a thin film multilayer structure, whose core consists of two ferromagnetic electrodes, separated by an insulating layer. One of the electrodes is magnetically pinned via exchange bias to an antiferromagnetic layer, while the other is free to react to an external magnetic field. The magnetization of the pinned layer is fixed in a perpendicular direction, so this ferromagnetic junction can be used as a low-field magnetic sensor. The magnetoresistance of the junction is dependent on the magnetic orientation of the electrodes, and is quantified as the percent change between the low and high resistance states. The higher its value, the more sensitive the device is, which makes the MTJ sensor (magnetoresistance exceeding 200%) particularly attractive for detecting small-scale magnetic structures. The MTJ sensor does not require the use of cryogens, enabling straightforward, low-cost operation of the microscope. The lack of cryogen technology means the sensor can be brought close to the sample surface, routinely allowing for sample-to-sensor distances of 15-20 μm. Scan height depends on factors such as scanning mode (if using a static or vibrating stage), sample surface configuration, or sensor configuration (i.e., proximity of the sensor to the tip of the die). This renders the MTJ microscope capable of producing magnetic images that may resolve features as small as 15 μm, and of detecting field intensities lower than 1 μT. This technology is particularly useful for detecting stray fields from micro-regions of interest preserving the original paleomagnetic signature within a bulk sample that may also contain remagnetised regions. Examples include ancient or altered rocks, extraterrestrial materials, samples containing inclusions or exsolution structures, and in general specimens

  16. [Scanning electron microscope study of chemically disinfected endodontic files].

    PubMed

    Navarro, G; Mateos, M; Navarro, J L; Canalda, C

    1991-01-01

    Forty stainless steel endodontic files were observed at scanning electron microscopy after being subjected to ten disinfection cycles of 10 minutes each one, immersed in different chemical disinfectants. Corrosion was not observed on the surface of the files in circumstances that this study was made.

  17. [Scanning electron microscope study of chemically disinfected endodontic files].

    PubMed

    Navarro, G; Mateos, M; Navarro, J L; Canalda, C

    1991-01-01

    Forty stainless steel endodontic files were observed at scanning electron microscopy after being subjected to ten disinfection cycles of 10 minutes each one, immersed in different chemical disinfectants. Corrosion was not observed on the surface of the files in circumstances that this study was made. PMID:1659857

  18. A high-voltage scanning transmission electron microscope at Nagoya University.

    PubMed

    Hibino, M; Shimoyama, H; Maruse, S

    1989-07-01

    A high-voltage scanning transmission electron microscope (STEM) H-1250ST of the maximum accelerating voltage of 1.25 MV was constructed at Nagoya University in 1983. The microscope, equipped with a field-emission gun, is designed with high-level STEM performance as well as conventional transmission microscopy mode operation. The aim of developing the microscope, basic design schemes, principal instrumentation, and techniques developed are described.

  19. Large area fabrication of plasmonic nanoparticle grating structure by conventional scanning electron microscope

    SciTech Connect

    Sudheer, Tiwari, P.; Rai, V. N.; Srivastava, A. K.; Mukharjee, C.

    2015-06-24

    Plasmonic nanoparticle grating (PNG) structure of different periods has been fabricated by electron beam lithography using silver halide based transmission electron microscope film as a substrate. Conventional scanning electron microscope is used as a fabrication tool for electron beam lithography. Optical microscope and energy dispersive spectroscopy (EDS) have been used for its morphological and elemental characterization. Optical characterization is performed by UV-Vis absorption spectroscopic technique.

  20. Quantitative analysis of scanning tunneling microscopy images of mixed-ligand-functionalized nanoparticles.

    PubMed

    Biscarini, Fabio; Ong, Quy Khac; Albonetti, Cristiano; Liscio, Fabiola; Longobardi, Maria; Mali, Kunal S; Ciesielski, Artur; Reguera, Javier; Renner, Christoph; De Feyter, Steven; Samorì, Paolo; Stellacci, Francesco

    2013-11-12

    Ligand-protected gold nanoparticles exhibit large local curvatures, features rapidly varying over small scales, and chemical heterogeneity. Their imaging by scanning tunneling microscopy (STM) can, in principle, provide direct information on the architecture of their ligand shell, yet STM images require laborious analysis and are challenging to interpret. Here, we report a straightforward, robust, and rigorous method for the quantitative analysis of the multiscale features contained in STM images of samples consisting of functionalized Au nanoparticles deposited onto Au/mica. The method relies on the analysis of the topographical power spectral density (PSD) and allows us to extract the characteristic length scales of the features exhibited by nanoparticles in STM images. For the mixed-ligand-protected Au nanoparticles analyzed here, the characteristic length scale is 1.2 ± 0.1 nm, whereas for the homoligand Au NPs this scale is 0.75 ± 0.05 nm. These length scales represent spatial correlations independent of scanning parameters, and hence the features in the PSD can be ascribed to a fingerprint of the STM contrast of ligand-protected nanoparticles. PSD spectra from images recorded at different laboratories using different microscopes and operators can be overlapped across most of the frequency range, proving that the features in the STM images of nanoparticles can be compared and reproduced.

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

    SciTech Connect

    Valencia, Victor A.; Thaker, Avesh A.; Derouin, Jonathan; Valencia, Damian N.; Farber, Rachael G.; Gebel, Dana A.; Killelea, Daniel R.

    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)

  2. Scanning Tunneling Microscopy Study on Strongly Correlated Materials

    NASA Astrophysics Data System (ADS)

    He, Yang

    Strongly correlated electrons and spin-orbit interaction have been the two major research directions of condensed matter physics in recent years. The discovery of high temperature superconductors in 1986 not only brought excitement into the field but also challenged our theory on quantum materials. After almost three decades of extensive study, the underlying mechanism of high temperature superconductivity is still not fully understood, the reason for which is mainly a poor understanding of strongly correlated systems. The phase diagram of cuprate superconductors has become more complicated throughout the years as multiple novel electronic phases have been discovered, while few of them are fully understood. Topological insulators are a newly discovered family of materials bearing topological non-trivial quantum states as a result of spin-orbit coupling. The theoretically predicted topological Kondo insulators as strongly correlated systems with strong spin-orbital coupling make an ideal playground to test our theory of quantum materials. Scanning tunneling microscopy (STM) is a powerful technique to explore new phenomena in materials with exotic electronic states due to its high spacial resolution and high sensitivity to low energy electronic structures. Moreover, as a surface-sensitive technique, STM is an ideal tool to investigate the electronic properties of topological and non-topological surface states. In this thesis, I will describe experiments we performed on high temperature superconductors and topological Kondo insulators using STM. First, I will describe our experiments on a Bi-based high temperature superconductor Bi2Sr2CuO6+delta. The quasiparticle interference technique uncovers a Fermi surface reconstruction. We also discovered the coexistence of Bogoliubov quasiparticle and pseudogap state at the antinodes. Afterwards, I will discuss our discovery of d-form factor density wave in the same material, showing the omnipresence of d form factor density

  3. Surface confined metallosupramolecular architectures: formation and scanning tunneling microscopy characterization.

    PubMed

    Li, Shan-Shan; Northrop, Brian H; Yuan, Qun-Hui; Wan, Li-Jun; Stang, Peter J

    2009-02-17

    Metallosupramolecular compounds have attracted a great deal of attention over the past two decades largely because of their unique, highly complex structural characteristics and their potential electronic, magnetic, optical, and catalytic properties. These molecules can be prepared with relative ease using coordination-driven self-assembly techniques. In particular, the use of electron-poor square-planar Pt(II) transition metals in conjunction with rigid, electron-rich pyridyl donors has enabled the spontaneous self-assembly of a rich library of 2D metallacyclic and 3D metallacage assemblies via the directional-bonding approach. With this progress in the preparation and characterization of metallosupramolecules, researchers have now turned their attention toward fully exploring and developing their materials properties. Assembling metallosupramolecular compounds on solid supports represents a vitally important step toward developing their materials properties. Surfaces provide a means of uniformly aligning and orienting these highly symmetric metallacycles and metallacages. This uniformity increases the level of coherence between molecules above that which can be achieved in the solution phase and provides a way to integrate adsorbed layers, or adlayers, into a solid-state materials setting. The dynamic nature of kinetically labile Pt(II)-N coordination bonds requires us to adjust deposition and imaging conditions to retain the assemblies' stability. Toward these aims, we have used scanning tunneling microscopy (STM) to image these adlayers and to understand the factors that govern surface self-assembly and the interactions that influence their structure and stability. This Account describes our efforts to deposit 2D rectangular and square metallacycles and 3D trigonal bipyramidal and chiral trigonal prism metallacages on highly oriented pyrolytic graphite (HOPG) and Au(111) substrates to give intact assemblies and ordered adlayers. We have investigated the effects

  4. Angularly-selective transmission imaging in a scanning electron microscope.

    PubMed

    Holm, Jason; Keller, Robert R

    2016-08-01

    This work presents recent advances in transmission scanning electron microscopy (t-SEM) imaging control capabilities. A modular aperture system and a cantilever-style sample holder that enable comprehensive angular selectivity of forward-scattered electrons are described. When combined with a commercially available solid-state transmission detector having only basic bright-field and dark-field imaging capabilities, the advances described here enable numerous transmission imaging modes. Several examples are provided that demonstrate how contrast arising from diffraction to mass-thickness can be obtained. Unanticipated image contrast at some imaging conditions is also observed and addressed. PMID:27179301

  5. Angularly-selective transmission imaging in a scanning electron microscope.

    PubMed

    Holm, Jason; Keller, Robert R

    2016-08-01

    This work presents recent advances in transmission scanning electron microscopy (t-SEM) imaging control capabilities. A modular aperture system and a cantilever-style sample holder that enable comprehensive angular selectivity of forward-scattered electrons are described. When combined with a commercially available solid-state transmission detector having only basic bright-field and dark-field imaging capabilities, the advances described here enable numerous transmission imaging modes. Several examples are provided that demonstrate how contrast arising from diffraction to mass-thickness can be obtained. Unanticipated image contrast at some imaging conditions is also observed and addressed.

  6. STEM electron tomography in the Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Ferroni, M.; Signoroni, A.; Sanzogni, A.; Sberveglieri, G.; Migliori, A.; Ortolani, L.; Christian, M.; Masini, L.; Morandi, V.

    2015-10-01

    The scanning-transmission imaging mode in the SEM allows for the threedimensional tomographic reconstruction of a specimen, starting from a set of projection images. Compressed sensing was used to solve the undetermined problem of structure reconstruction and was proven capable of overcoming the limitations arising from the sampling scheme. Reconstructions of cobalt particles within a carbon nanotube and collagen fibrils in a dermal tissue are presented, demonstrating the potential of this technique in the set of 3-D electron microscopy methods for both physical and biological science.

  7. Imaging graphite in air by scanning tunneling microscopy - Role of the tip

    NASA Astrophysics Data System (ADS)

    Colton, R. J.; Baker, S. M.; Driscoll, R. J.; Youngquist, M. G.; Baldeschwieler, J. D.; Kaiser, W. J.

    1988-04-01

    Atomically resolved images of highly oriented pyrolytic graphite (HOPG) in air at point contact have been obtained. Direct contact between tip and sample or contact through a contamination layer provides a conduction mechanism in addition to the exponential tunneling mechanism responsible for scanning tunneling microscopy (STM) imaging. Current-voltage (I-V) spectra were obtained while scanning in the current imaging mode with the feedback circuit interrupted in order to study the graphite imaging mechanism. Multiple tunneling tips are probably responsible for images without the expected hexagonal or trigonal symmetry. The observations indicate that the use of HOPG for testing and calibration of STM instrumentation may be misleading.

  8. [Examination of the uterine cervix using the scanning electron microscope].

    PubMed

    Lerat, M F; Magre, J; Connehaye, P; Lerat, H; Barreau, A

    1975-01-01

    Scanning by electron microscopy of the cervix of the uterus allows us to study the various aspects, both normal and pathological, as well as the architecture of sections of the organ. All the same, as in all practical examinations carried out using scanning we have to beware of pictures that are but artefacts due to the method of preparation. The views obtained from a normal cervix of from pathological cervices show very different aspects. In the normal cervix the surfaces are more or less smooth and the architecture of the deeper levels shows a thick and regular texture. Infectious lesions of the outer aspect of the cervix show punched-out patterns, like craters, which penetrate more or less deeply into the sub-epithelial plane. While cervical dysplasia shows little except perhaps a more or less bossed-up epithelial surface, cancer of the cervix on the other hand shows a pavement pattern which is irregular. The pavements are formed by buds which are separated by faults which are more or less deep. In section the structures show a degree of disorientation in the texture. After treatment with radium the appearance is rather like ground glass of spiders webs and the architecture of the structures seems to be pock-marked and chaotic.

  9. Compact scanning transmission x-ray microscope at the photon factory

    NASA Astrophysics Data System (ADS)

    Takeichi, Yasuo; Inami, Nobuhito; Suga, Hiroki; Takahashi, Yoshio; Ono, Kanta

    2016-01-01

    We report the design and performance of a compact scanning transmission X-ray microscope developed at the Photon Factory. Piezo-driven linear stages are used as coarse stages of the microscope to realize excellent compactness, mobility, and vibrational and thermal stability. An X-ray beam with an intensity of ˜107 photons/s was focused to a diameter of ˜40 nm at the sample. At the soft X-ray undulator beamline used with the microscope, a wide range of photon energies (250-1600 eV) is available. The microscope has been used to research energy materials and in environmental sciences.

  10. Confocal laser scanning microscopic photoconversion: a new method to stabilize fluorescently labeled cellular elements for electron microscopic analysis

    PubMed Central

    Colello, Raymond J.; Tozer, Jordan; Henderson, Scott C.

    2012-01-01

    Photoconversion, the method by which a fluorescent dye is transformed into a stable, osmiophilic product that can be visualized by electron microscopy, is the most widely used method to enable the ultrastructural analysis of fluorescently-labeled cellular structures. Nevertheless, the conventional method of photoconversion using widefield fluorescence microscopy requires long reaction times and results in low resolution cell targeting. Accordingly, we have developed a photoconversion method that ameliorates these limitations by adapting confocal laser scanning microscopy to the procedure. We have found that this method greatly reduces photoconversion times as compared to conventional wide field microscopy. Moreover, region of interest scanning capabilities of a confocal microscope facilitate the targeting of the photoconversion process to individual cellular or subcellular elements within a fluorescent field. This reduces the area of the cell exposed to light energy, thereby reducing the ultrastructural damage common to this process when widefield microscopes are employed. PMID:23042499

  11. Quantitative measurement of piezoelectric coefficient of thin film using a scanning evanescent microwave microscope

    NASA Astrophysics Data System (ADS)

    Zhao, Zhenli; Luo, Zhenlin; Liu, Chihui; Wu, Wenbin; Gao, Chen; Lu, Yalin

    2008-06-01

    This article describes a new approach to quantitatively measure the piezoelectric coefficients of thin films at the microscopic level using a scanning evanescent microwave microscope. This technique can resolve 10pm deformation caused by the piezoelectric effect and has the advantages of high scanning speed, large scanning area, submicron spatial resolution, and a simultaneous accessibility to many other related properties. Results from the test measurements on the longitudinal piezoelectric coefficient of PZT thin film agree well with those from other techniques listed in literatures.

  12. Parallel, miniaturized scanning probe microscope for defect inspection and review

    NASA Astrophysics Data System (ADS)

    Sadeghian, H.; van den Dool, T. C.; Crowcombe, W. E.; Herfst, R. W.; Winters, J.; Kramer, G. F. I. J.; Koster, N. B.

    2014-04-01

    With the device dimensions moving towards the 1X node, the semiconductor industry is rapidly approaching the point where 10 nm defects become critical. Therefore, new methods for improving the yield are emerging, including inspection and review methods with sufficient resolution and throughput. Existing industrial tools cannot anymore fulfill these requirements for upcoming smaller and 3D features, since they are performing at the edge of their performance. Scanning probe microscopy (SPM) has the ability to accurately measure dimensions in the micrometer to nanometer scale. Examples of applications are surface roughness, channel height and width measurement, defect inspection in wafers, masks and flat panel displays. In most of these applications, the target area is very large, and, therefore, the throughput of the measurement plays an important role in the final production cost. Single SPM has never been able to compete with other inspection systems in terms of measurement speed, thus has not fulfilled the industry needs in throughput and cost. Further increase of the speed of the single SPM helps, but it still is far from the required throughput and, therefore, insufficient for high-volume manufacturing. Over the past three years, we have developed a revolutionary concept for a multiple miniaturized SPM heads system, which can inspect and measure many sites in parallel. The very high speed of each miniaturized SPM unit allow the user to scan many areas, each with the size of tens of micrometers, in a few seconds. This paper presents an overview of the technical developments and experimental results of the parallel SPM system for wafer and mask inspection.

  13. Visualization of Photo-induced Doping patterns in Graphene/Boron Nitride Heterostructures via Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Velasco, Jairo, Jr.; Ju, Long; Wong, Dillon; Lee, Juwon; Kahn, Salman; Tsai, Hsin-Zon; Germany, Chad; Taniguchi, Takashi; Watanabe, Kenji; Zettl, Alex; Wang, Feng; Crommie, Mike

    2015-03-01

    Photo-induced doping in graphene-boron nitride (G/BN) heterostructures enables flexible and repeatable writing and erasing of charge doping in graphene using optical irradiation. So far, however, this phenomenon has been explored using spatially averaging probes such as electron transport, and there have been no local studies into the underlying microscopic behavior. Here we report a combined scanning tunneling microscopy (STM) and optoelectronic measurement scheme that has been utilized to investigate the microscopic mechanisms at work in this process. We will discuss the latest experimental progress towards the visualization of light-induced charge doping patterns on G/BN heterostructures via STM. J.V.J. acknowledges support from the UC President's Postdoctoral Fellowship.

  14. High-resolution imaging in the scanning transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Pennycook, S. J.; Jesson, D. E.

    1992-03-01

    The high-resolution imaging of crystalline materials in the scanning transmission electron microscopy (STEM) is reviewed with particular emphasis on the conditions under which an incoherent image can be obtained. It is shown that a high-angle annular detector can be used to break the coherence of the imaging process, in the transverse plane through the geometry of the detector, or in three dimensions if multiphonon diffuse scattering is detected. In the latter case, each atom can be treated as a highly independent source of high-angle scattering. The most effective fast electron states are therefore tightly bound s-type Bloch states. Furthermore, they add constructively for each incident angle in the coherent STEM probe, so that s states are responsible for practically the entire image contrast. Dynamical effects are largely removed, and almost perfect incoherent imaging is achieved. S states are relatively insensitive to neighboring strings, so that incoherent imaging is maintained for superlattice and interfaces, and supercell calculations are unnecessary. With an optimum probe profile, the incoherent image represents a direct image of the crystal projection, with compositional sensitivity built in through the strong dependence of the scattering cross sections on atomic number Z.

  15. In situ fatigue loading stage inside scanning electron microscope

    NASA Technical Reports Server (NTRS)

    Telesman, Jack; Kantzos, Peter; Brewer, David

    1988-01-01

    A fatigue loading stage inside a scanning electron microscopy (SEM) was developed. The stage allows dynamic and static high-magnification and high-resolution viewing of the fatigue crack initiation and crack propagation processes. The loading stage is controlled by a closed-loop servohydraulic system. Maximum load is 1000 lb (4450 N) with test frequencies ranging up to 30 Hz. The stage accommodates specimens up to 2 inches (50 mm) in length and tolerates substantial specimen translation to view the propagating crack. At room temperature, acceptable working resolution is obtainable for magnifications ranging up to 10,000X. The system is equipped with a high-temperature setup designed for temperatures up to 2000 F (1100 C). The signal can be videotaped for further analysis of the pertinent fatigue damage mechanisms. The design allows for quick and easy interchange and conversion of the SEM from a loading stage configuration to its normal operational configuration and vice versa. Tests are performed entirely in the in-situ mode. In contrast to other designs, the NASA design has greatly extended the life of the loading stage by not exposing the bellows to cyclic loading. The loading stage was used to investigate the fatigue crack growth mechanisms in the (100)-oriented PWA 1480 single-crystal, nickel-based supperalloy. The high-magnification observations revealed the details of the crack growth processes.

  16. Flow cytometric and laser scanning microscopic approaches in epigenetics research.

    PubMed

    Szekvolgyi, Lorant; Imre, Laszlo; Minh, Doan Xuan Quang; Hegedus, Eva; Bacso, Zsolt; Szabo, Gabor

    2009-01-01

    Our understanding of epigenetics has been transformed in recent years by the advance of technological possibilities based primarily on a powerful tool, chromatin immunoprecipitation (ChIP). However, in many cases, the detection of epigenetic changes requires methods providing a high-throughput (HTP) platform. Cytometry has opened a novel approach for the quantitative measurement of molecules, including PCR products, anchored to appropriately addressed microbeads (Pataki et al. 2005. Cytometry 68, 45-52). Here we show selected examples for the utility of two different cytometry-based platforms of epigenetic analysis: ChIP-on-beads, a flow-cytometric test of local histone modifications (Szekvolgyi et al. 2006. Cytometry 69, 1086-1091), and the laser scanning cytometry-based measurement of global epigenetic modifications that might help predict clinical behavior in different pathological conditions. We anticipate that such alternative tools may shortly become indispensable in clinical practice, translating the systematic screening of epigenetic tags from basic research into routine diagnostics of HTP demand.

  17. Novel Scanning Near-Field Microwave Microscopes Capable of Imaging Semiconductors and Metals

    NASA Astrophysics Data System (ADS)

    Imtiaz, Atif; Tselev, Alexander; Anlage, Steven

    2003-03-01

    To study novel physics in condensed matter and materials science, experimental techniques of probing the high frequency electrical properties of materials are limited in resolution to the wavelength of the incident electromagnetic wave. We report here a novel near-field microscope that is capable of operation at radio and microwave frequencies[1]. The spatial resolution is comparable to NSOM in the scanning capacitance mode of the microscope[2]. Our objective is to image materials contrast at microwave frequencies and improve the spatial resolution. The microscope is sensitive to losses in materials, and we will present evidence of sheet resistance contrast in a Boron-doped Silicon sample. These experiments are performed with two versions of the near-field microwave microscope: one has integrated STM-feedback for distance control and the second one maintains a constant frequency shift through Distance Following technique. We will discuss the data on these films in light of a transmission line and lumped element model of the microscope. The microscope is an attractive platform for measuring local losses and local nonlinear properties of a rich variety of semiconducting and correlated-electron materials. [1] D.E. Steinhauer, et.al, "Quantitative Imaging of Sheet Resistance with a Scanning Near-Field Microwave Microscope", Appl. Phys. Lett. 72, 861 (1998) [2] Atif Imtiaz and Steven M. Anlage, "A novel STM-assisted microwave microscope with capacitance and loss imaging capability", Ultramicroscopy (in press); cond-mat/0203540

  18. Note: A scanning electron microscope sample holder for bidirectional characterization of atomic force microscope probe tips

    SciTech Connect

    Eisenstein, Alon; Goh, M. Cynthia

    2012-03-15

    A novel sample holder that enables atomic force microscopy (AFM) tips to be mounted inside a scanning electron microscopy (SEM) for the purpose of characterizing the AFM tips is described. The holder provides quick and easy handling of tips by using a spring clip to hold them in place. The holder can accommodate two tips simultaneously in two perpendicular orientations, allowing both top and side view imaging of the tips by the SEM.

  19. Basic properties of GaAs oxide generated by scanning probe microscope tip-induced nano-oxidation process

    NASA Astrophysics Data System (ADS)

    Okada, Yoshitaka; Iuchi, Yoshimasa; Kawabe, Mitsuo; Harris, James S.

    2000-07-01

    The basic properties of GaAs oxide generated by atomic force microscope (AFM) tip-induced nano-oxidation process have been investigated. The chemical analysis of the AFM tip-generated GaAs oxide was performed by using scanning microprobe x-ray photoelectron spectroscopy, and the main constituents of GaAs anodic oxide were determined to be Ga2O3 and As2O3. The electrical characterization showed that the electron transport across a GaAs oxide nanodot of ˜5.7 nm thickness, from a doped n+-Si tip into the n+-GaAs substrate follows the Fowler-Nordheim tunneling mechanism over a range of applied bias. Further, the tip-generated GaAs oxide nanodots were found to withstand moderate thermal treatments, but some volume reduction was observed.

  20. Scanning tunneling microscopy of Cu, Ag, Au and Al adatoms, small clusters, and islands on graphite

    NASA Astrophysics Data System (ADS)

    Ganz, Eric; Sattler, Klaus; Clarke, John

    1989-09-01

    We have used a scanning tunneling microscope to study the static and dynamic behaviour of Cu, Ag, Au, and Al deposited in situ on highly oriented pyrolytic graphite in an ultra-high vacuum chamber. We have imaged static monomers of Ag, Au, and Al, dimers of Ag and Au, and clusters of 3 or more atoms of Ag, Al, and Au. From the lifetime of the monomers, we estimate the energy barrier against diffusion to be greater than 0.65 eV. We have studied two-dimensional islands of Ag and Au, containing up to 100 atoms, which are atomically resolved against the supporting graphite substrate. The interiors of the islands contain ordered rectangular lattices separated by grain boundaries, while the atoms at the periphery are disordered. We show a small three-dimensional Cu crystal, the decoration of a grain boundary by Cu particles with an average diameter of 44 Å, and two examples of granular films. Finally, we present examples of dynamic processes: the shrinking of a small Au island, the contraction of the lattice spacing of a rectangular two-dimensional Au lattice on a time scale of minutes, and the diffusion of a Ag cluster along a graphite step edge on a time scale of seconds.

  1. Scanning Tunneling Microscopy of the π Magnetism of a Single Carbon Vacancy in Graphene

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Li, Si-Yu; Huang, Huaqing; Li, Wen-Tian; Qiao, Jia-Bin; Wang, Wen-Xiao; Yin, Long-Jing; Bai, Ke-Ke; Duan, Wenhui; He, Lin

    2016-10-01

    Pristine graphene is strongly diamagnetic. However, graphene with single carbon atom defects could exhibit paramagnetism. Theoretically, the π magnetism induced by the monovacancy in graphene is characteristic of two spin-split density-of-states (DOS) peaks close to the Dirac point. Since its prediction, many experiments have attempted to study this π magnetism in graphene, whereas only a notable resonance peak has been observed around the atomic defects, leaving the π magnetism experimentally elusive. Here, we report direct experimental evidence of π magnetism by using a scanning tunneling microscope. We demonstrate that the localized state of the atomic defects is split into two DOS peaks with energy separations of several tens of meV. Strong magnetic fields further increase the energy separations of the two spin-polarized peaks and lead to a Zeeman-like splitting. Unexpectedly, the effective g factor around the atomic defect is measured to be about 40, which is about 20 times larger than the g factor for electron spins.

  2. Tip-Dependent Scanning Tunneling Microscopy Imaging of Ultrathin FeO Films on Pt(111)

    SciTech Connect

    Merte, L. R.; Grabow, Lars C.; Peng, Guowen; Knudsen, Jan; Zeuthen, Helene; Kudernatsch, Wilhelmine; Porsgaard, Soeren; Laegsgaard, E.; Mavrikakis, Manos; Besenbacher, Fleming

    2011-02-10

    High-resolution scanning tunneling microscope (STM) images of moire-structured FeO films on Pt(111) were obtained in a number of different tip-dependent imaging modes. For the first time, the STM images are distinguished and interpreted unambiguously with the help of distinct oxygen- vacancy dislocation loops in the FeO moire structure. The experimental STM results are compared with the results of electronic structure calculations within the DFTþUscheme for a realistic (√91 x √ 91)R5.2º moire FeO unit cell supported on Pt(111) as well as with the results from previous studies. We find that one type of STM imaging mode, showing both Fe and O atoms, agrees well with simulated STM images, indicating that the simple Tersoff-Hamann theory is partially valid for this imaging mode. In addition, we identify other distinct, element-specific imaging modes which reveal a strong dependence on the specific tip apex state and likely result from specific tip-sample chemical interactions. From the present STMresults we show that several of the previously published conclusions for the FeO system have to be revisited.

  3. Ag/ZnO hybrid systems studied with scanning tunnelling microscopy-based luminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Pascua, Leandro; Stavale, Fernando; Nilius, Niklas; Freund, Hans-Joachim

    2016-03-01

    Coupled metal/oxide systems are prepared by depositing and embedding Ag nanoparticles into crystalline ZnO films grown on Au(111) supports. The morphology and optical properties of the compounds are investigated by topographic imaging and luminescence spectroscopy performed in a scanning tunnelling microscope (STM). The luminescence of bare ZnO is governed by the band-recombination and a Zn-vacancy related peak. After Ag deposition, two additional maxima are detected that are assigned to the in-plane and out-of-plane plasmon in Ag nanoparticles and have energies below and slightly above the oxide band-gap, respectively. Upon coating the particles with additional ZnO, the out-of-plane plasmon redshifts and loses intensity, indicating strong coupling to the oxide electronic system, while the in-plane mode broadens but remains detectable. The original situation can be restored by gently heating the sample, which drives the silver back to the surface. However, the optical response of pristine ZnO is not recovered even after silver evaporation at high temperature. Small discrepancies are explained with changes in the ZnO defect landscape, e.g., due to silver incorporation. Our experiments demonstrate how energy-transfer processes can be investigated in well-defined metal/oxide systems by means of STM-based spectroscopic techniques.

  4. A new apparatus for electron tomography in the scanning electron microscope

    SciTech Connect

    Morandi, V. Maccagnani, P.; Masini, L.; Migliori, A.; Ortolani, L.; Pezza, A.; Del Marro, M.; Pallocca, G.; Vinciguerra, P.; Rossi, M.; Ferroni, M.; Sberveglieri, G.; Vittori-Antisari, M.

    2015-06-23

    The three-dimensional reconstruction of a microscopic specimen has been obtained by applying the tomographic algorithm to a set of images acquired in a Scanning Electron Microscope. This result was achieved starting from a series of projections obtained by stepwise rotating the sample under the beam raster. The Scanning Electron Microscope was operated in the scanning-transmission imaging mode, where the intensity of the transmitted electron beam is a monotonic function of the local mass-density and thickness of the specimen. The detection strategy has been implemented and tailored in order to maintain the projection requirement over the large tilt range, as required by the tomographic workflow. A Si-based electron detector and an eucentric-rotation specimen holder have been specifically developed for the purpose.

  5. Microscopic tomography by laser scanning microscopy and its three-dimensional reconstruction.

    PubMed

    Takamatsu, T; Fujita, S

    1988-03-01

    We have developed a new confocal laser scanning microscope equipped with two galvanometer mirrors which swing the laser beam. With this set up we can observe large and fragile specimens. Using a focused laser beam as light source to minimize 'flare' and a pinhole in front of a photodetector to eliminate out-of-focus data, we could obtain a depth-discriminated fluorescence image. The scanning apparatus of our system can eliminate mechanical vibration and sweep widely, to obtain images at a low magnification. A thinly sectioned image with high resolution and high contrast could be obtained optically from an in situ thick specimen. We have called this technique 'microscopic tomography'. Combining the laser scanning microscope with the colour image analyser generated semi-automatically a three-dimensional picture of the biological material with information on its interior. PMID:3398041

  6. Local imaging of high mobility two-dimensional electron systems with virtual scanning tunneling microscopy

    SciTech Connect

    Pelliccione, M.; Bartel, J.; Goldhaber-Gordon, D.; Sciambi, A.; Pfeiffer, L. N.; West, K. W.

    2014-11-03

    Correlated electron states in high mobility two-dimensional electron systems (2DESs), including charge density waves and microemulsion phases intermediate between a Fermi liquid and Wigner crystal, are predicted to exhibit complex local charge order. Existing experimental studies, however, have mainly probed these systems at micron to millimeter scales rather than directly mapping spatial organization. Scanning probes should be well-suited to study the spatial structure of these states, but high mobility 2DESs are found at buried semiconductor interfaces, beyond the reach of conventional scanning tunneling microscopy. Scanning techniques based on electrostatic coupling to the 2DES deliver important insights, but generally with resolution limited by the depth of the 2DES. In this letter, we present our progress in developing a technique called “virtual scanning tunneling microscopy” that allows local tunneling into a high mobility 2DES. Using a specially designed bilayer GaAs/AlGaAs heterostructure where the tunnel coupling between two separate 2DESs is tunable via electrostatic gating, combined with a scanning gate, we show that the local tunneling can be controlled with sub-250 nm resolution.

  7. Local imaging of high mobility two-dimensional electron systems with virtual scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Pelliccione, M.; Bartel, J.; Sciambi, A.; Pfeiffer, L. N.; West, K. W.; Goldhaber-Gordon, D.

    2014-11-01

    Correlated electron states in high mobility two-dimensional electron systems (2DESs), including charge density waves and microemulsion phases intermediate between a Fermi liquid and Wigner crystal, are predicted to exhibit complex local charge order. Existing experimental studies, however, have mainly probed these systems at micron to millimeter scales rather than directly mapping spatial organization. Scanning probes should be well-suited to study the spatial structure of these states, but high mobility 2DESs are found at buried semiconductor interfaces, beyond the reach of conventional scanning tunneling microscopy. Scanning techniques based on electrostatic coupling to the 2DES deliver important insights, but generally with resolution limited by the depth of the 2DES. In this letter, we present our progress in developing a technique called "virtual scanning tunneling microscopy" that allows local tunneling into a high mobility 2DES. Using a specially designed bilayer GaAs/AlGaAs heterostructure where the tunnel coupling between two separate 2DESs is tunable via electrostatic gating, combined with a scanning gate, we show that the local tunneling can be controlled with sub-250 nm resolution.

  8. Response function and optimum configuration of semiconductor backscattered-electron detectors for scanning electron microscopes

    SciTech Connect

    Rau, E. I.; Orlikovskiy, N. A.; Ivanova, E. S.

    2012-06-15

    A new highly efficient design for semiconductor detectors of intermediate-energy electrons (1-50 keV) for application in scanning electron microscopes is proposed. Calculations of the response function of advanced detectors and control experiments show that the efficiency of the developed devices increases on average twofold, which is a significant positive factor in the operation of modern electron microscopes in the mode of low currents and at low primary electron energies.

  9. Imaging properties and its improvements of scanning/imaging x-ray microscope

    NASA Astrophysics Data System (ADS)

    Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio

    2016-01-01

    A scanning / imaging X-ray microscope (SIXM) system has been developed at SPring-8. The SIXM consists of a scanning X-ray microscope with a one-dimensional (1D) X-ray focusing device and an imaging (full-field) X-ray microscope with a 1D X-ray objective. The motivation of the SIXM system is to realize a quantitative and highly-sensitive multimodal 3D X-ray tomography by taking advantages of both the scanning X-ray microscope using multi-pixel detector and the imaging X-ray microscope. Data acquisition process of a 2D image is completely different between in the horizontal direction and in the vertical direction; a 1D signal is obtained with the linear-scanning while the other dimensional signal is obtained with the imaging optics. Such condition have caused a serious problem on the imaging properties that the imaging quality in the vertical direction has been much worse than that in the horizontal direction. In this paper, two approaches to solve this problem will be presented. One is introducing a Fourier transform method for phase retrieval from one phase derivative image, and the other to develop and employ a 1D diffuser to produce an asymmetrical coherent illumination.

  10. Efficient electrochemical etching method to fabricate sharp metallic tips for scanning probe microscopes

    SciTech Connect

    Kim, Pilkyu; Kim, Jun Ho; Jeong, Mun Seok; Ko, Do-Kyeong; Lee, Jongmin; Jeong, Sungho

    2006-10-15

    A new technique based on electrochemical etching for the fabrication of sharp metallic tips for scanning probe microscopes is introduced. In the proposed method, a small Teflon mass is attached to the end of an immersed tungsten wire using an aluminum tape, which leads to a significant enhancement of yield rate of sharp tungsten tips with an apex size below 100 nm to over 60%. The functionality of the tungsten tips fabricated by the proposed method is verified by measuring the topography of a standard sample using a shear-force scanning probe microscope.

  11. Determination of surface topography of biological specimens at high resolution by scanning tunnelling microscopy.

    PubMed

    Baró, A M; Miranda, R; Alamán, J; García, N; Binnig, G; Rohrer, H; Gerber, C; Carrascosa, J L

    Although techniques are available for the determination of the three-dimensional structure of biological specimens, for example scanning electron microscopy, they all have some serious drawback, such as low resolution, the requirement for crystals or for the sample to be analysed in a high vacuum. In an attempt to develop a technique for high-resolution three-dimensional structure analysis of non-crystalline biological material, we have tested the applicability of scanning tunnelling microscopy (STM), a method that has been used successfully in the analysis of metal and semiconductor surface structures. We report here that scanning tunnelling electron microscopy can be used to determine the surface topography of biological specimens at atmospheric pressure and room temperature, giving a vertical resolution of the order of 1 A. Our results show that quantum mechanical tunnelling of electrons through biological material is possible provided that the specimen is deposited on a conducting surface.

  12. System design and new applications for atomic force microscope based on tunneling

    NASA Astrophysics Data System (ADS)

    Wang, X.; Liu, A. P.; Yang, X. H.

    2015-09-01

    The design of atomic force microscopy (AFM) with high resolution is introduced in this paper. Mainly, we have developed the system design of the apparatus based on tunneling. AFM.IPC-208B, this kind of apparatus combines scanning tunnel microscopy (STM) and AFM availability, and its lens body with original frame enhances the capability of the machine. In order to analyze the performance of AFM.IPC-208B, as a new tool in the field of Life Science, we make use of the system to study natural mica and molecular protein structures of Cattle-insulin and human antibody immunoglobulin G (IgG) coupled with staphylococcus protein A (SPA). As the results of new applications, the resolution of AFM.IPC-208B is proved to be 0.1 nm, and these nanometer measurement results provide much valuable information for the study of small molecular proteins and HIV experiments.

  13. High-resolution, high-throughput imaging with a multibeam scanning electron microscope

    PubMed Central

    EBERLE, AL; MIKULA, S; SCHALEK, R; LICHTMAN, J; TATE, ML KNOTHE; ZEIDLER, D

    2015-01-01

    Electron–electron interactions and detector bandwidth limit the maximal imaging speed of single-beam scanning electron microscopes. We use multiple electron beams in a single column and detect secondary electrons in parallel to increase the imaging speed by close to two orders of magnitude and demonstrate imaging for a variety of samples ranging from biological brain tissue to semiconductor wafers. Lay Description The composition of our world and our bodies on the very small scale has always fascinated people, making them search for ways to make this visible to the human eye. Where light microscopes reach their resolution limit at a certain magnification, electron microscopes can go beyond. But their capability of visualizing extremely small features comes at the cost of a very small field of view. Some of the questions researchers seek to answer today deal with the ultrafine structure of brains, bones or computer chips. Capturing these objects with electron microscopes takes a lot of time – maybe even exceeding the time span of a human being – or new tools that do the job much faster. A new type of scanning electron microscope scans with 61 electron beams in parallel, acquiring 61 adjacent images of the sample at the same time a conventional scanning electron microscope captures one of these images. In principle, the multibeam scanning electron microscope’s field of view is 61 times larger and therefore coverage of the sample surface can be accomplished in less time. This enables researchers to think about large-scale projects, for example in the rather new field of connectomics. A very good introduction to imaging a brain at nanometre resolution can be found within course material from Harvard University on http://www.mcb80x.org/# as featured media entitled ‘connectomics’. PMID:25627873

  14. Masked illumination scheme for a galvanometer scanning high-speed confocal fluorescence microscope.

    PubMed

    Kim, Dong Uk; Moon, Sucbei; Song, Hoseong; Kwon, Hyuk-Sang; Kim, Dug Young

    2011-01-01

    High-speed beam scanning and data acquisition in a laser scanning confocal microscope system are normally implemented with a resonant galvanometer scanner and a frame grabber. However, the nonlinear scanning speed of a resonant galvanometer can generate nonuniform photobleaching in a fluorescence sample as well as image distortion near the edges of a galvanometer scanned fluorescence image. Besides, incompatibility of signal format between a frame grabber and a point detector can lead to digitization error during data acquisition. In this article, we introduce a masked illumination scheme which can effectively decrease drawbacks in fluorescence images taken by a laser scanning confocal microscope with a resonant galvanometer and a frame grabber. We have demonstrated that the difference of photobleaching between the center and the edge of a fluorescence image can be reduced from 26 to 5% in our confocal laser scanning microscope with a square illumination mask. Another advantage of our masked illumination scheme is that the zero level or the lowest input level of an analog signal in a frame grabber can be accurately set by the dark area of a mask in our masked illumination scheme. We have experimentally demonstrated the advantages of our masked illumination method in detail.

  15. Masked illumination scheme for a galvanometer scanning high-speed confocal fluorescence microscope.

    PubMed

    Kim, Dong Uk; Moon, Sucbei; Song, Hoseong; Kwon, Hyuk-Sang; Kim, Dug Young

    2011-01-01

    High-speed beam scanning and data acquisition in a laser scanning confocal microscope system are normally implemented with a resonant galvanometer scanner and a frame grabber. However, the nonlinear scanning speed of a resonant galvanometer can generate nonuniform photobleaching in a fluorescence sample as well as image distortion near the edges of a galvanometer scanned fluorescence image. Besides, incompatibility of signal format between a frame grabber and a point detector can lead to digitization error during data acquisition. In this article, we introduce a masked illumination scheme which can effectively decrease drawbacks in fluorescence images taken by a laser scanning confocal microscope with a resonant galvanometer and a frame grabber. We have demonstrated that the difference of photobleaching between the center and the edge of a fluorescence image can be reduced from 26 to 5% in our confocal laser scanning microscope with a square illumination mask. Another advantage of our masked illumination scheme is that the zero level or the lowest input level of an analog signal in a frame grabber can be accurately set by the dark area of a mask in our masked illumination scheme. We have experimentally demonstrated the advantages of our masked illumination method in detail. PMID:21809349

  16. Multifocal axial confocal microscopic scanning with a phase-only liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Zou, Li Min; Pang, Ming Shu; Zhou, Meng Jiao; Wang, Bao Kai

    2015-02-01

    Aiming at the shortcomings of mechanical scanning methods, non-mechanical scanning method is proposed. A zoom illuminating lens which has multiple focal points is realized by introducing Liquid Crystal Spatial Light Modulator (LC-SLM) into the confocal illumination light path, and thus it produces the multifocal zoom lens axially. The axial optical sectioning in a conventional confocal microscope is achieved by beam scanning rather than mechanically moving the objective lens, which enhances the capacity of chromatography and improves the scanning speed with greater accuracy. To generate and shift the multiple axial focal points, the modulation phase bitmaps of LC-SLM is changed. Simulation results further show that multifocal axial confocal beam scanning replacing mechanical scanning can therefore be implemented.

  17. A Mythical History of the Scanning Probe Microscope - How it Could Have Been

    NASA Astrophysics Data System (ADS)

    Elings, Virgil

    2007-03-01

    The path from the ground breaking Topografiner by Young et. al. in 1972 to the current Atomic Force Microscopes was tortuous, to say the least. Now as an entrepreneur, they say that you should study the problem, work out a plan, and then execute the plan. Since this rarely works for me in real life, let's follow the mythical history of Phil the physics student whose simple approach to scanning probe microscopes during his summer job may explain life better than real life did. Comparisons between Phil's experience and real life will be made along the way to show how random real life was compared to Phil's straightforward approach. We will follow Phil as he goes from the Scanning Touching Microscope (STM) to the All Fancy Microscope (AFM) and ends up with a current scanning probe microscope. The ``lesson'' in this story is that when you are doing something new, you learn so much while you are doing it that what you thought at the beginning (the plan) is rarely the best way to go. It is more important, I believe, for entrepreneurs to explore possibilities and keep their eyes open along the way rather than pretend the path they are on is the right one. Phil is mythical because he always knew where he was headed and it was always the right direction. So how does Phil's story end? I'm working on it and will tell you at the March Meeting.

  18. Quantitative phase tomography by using x-ray microscope with Foucault knife-edge scanning filter

    NASA Astrophysics Data System (ADS)

    Watanabe, Norio; Tsuburaya, Yuji; Shimada, Akihiro; Aoki, Sadao

    2016-01-01

    Quantitative phase tomography was evaluated by using a differential phase microscope with a Foucault knife-edge scanning filter. A 3D x-ray phase image of polystyrene beads was obtained at 5.4 keV. The reconstructed refractive index was fairly good agreement with the Henke's tabulated data.

  19. Scanning electron microscope view of iron crystal growing on pyroxene crystal

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A scanning electron microscope photograph of a four-micron size iron crystal growing on a pyroxene crystal (calcium-magnesium-iron silicate) from the Apollo 15 Hadley-Apennino lunar landing site. The well developed crystal faces indicate that the crystal was formed from a hot vapor as the rock was cooling.

  20. Practical application of HgI2 detectors to a space-flight scanning electron microscope

    NASA Technical Reports Server (NTRS)

    Bradley, J. G.; Conley, J. M.; Albee, A. L.; Iwanczyk, J. S.; Dabrowski, A. J.

    1989-01-01

    Mercuric iodide X-ray detectors have been undergoing tests in a prototype scanning electron microscope system being developed for unmanned space flight. The detector program addresses the issues of geometric configuration in the SEM, compact packaging that includes separate thermoelectric coolers for the detector and FET, X-ray transparent hermetic encapsulation and electrical contacts, and a clean vacuum environment.

  1. Observation of semiconductor superstructures with backscattered electrons in a scanning electron microscope

    SciTech Connect

    Bosacchi, A.; Franchi, S.; Govoni, D.; Mattei, G.; Merli, P.G.; Migliori, A.; Nacucchi, M.

    1995-12-31

    Observations of semiconductor superstructures with backscattered electrons in a scanning electron microscope have been used to revisit the concept of resolution of the backscattering imaging mode. It will be shown that the generation volume doesn`t represent in itself a limit to the resolution, which depends only on the beam size and the signal to noise ratio.

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

    PubMed Central

    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. PMID:23112655

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

    PubMed

    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. PMID:23112655

  4. Quantitative scanning probe microscope topographies by charge linearization of the vertical actuator.

    PubMed

    Fleming, Andrew J

    2010-10-01

    Many forms of scanning probe microscopy require a piezoelectric actuator to vary the probe-sample distance. Examples include constant-force atomic force microscopy and constant-current scanning tunneling microscopy. In such modes, the topography of the sample is reconstructed from the voltage applied to the vertical piezoelectric actuator. However, piezoelectric actuators exhibit significant hysteresis which can produce up to 14% uncertainty in the reproduced topography. In this work, a charge drive is used to linearize the vertical piezoelectric actuator which reduces the error from 14% to 0.65%.

  5. Scanning image detection (SID) system for conventional transmission electron microscope (CTEM) images.

    PubMed

    Tanji, T; Tomita, M; Kobayashi, H

    1990-08-01

    A new image detection system has been developed to display transmission electron microscope (TEM) images on a CRT without a video camera system. Deflection coils placed in both the upper space of an objective lens and in the lower space of the first intermediate lens scan a small electron probe simultaneously. The electrical signal acquired through an improved scintillator and a photomultiplier is synchronized with the scanning signal and displayed in a similar fashion to a conventional scanning TEM (STEM) instrument. A preliminary system using a 100 kV conventional TEM (CTEM) equipped with a hairpin-type electron gun, produced an image with a spatial resolution of 1 nm.

  6. Confocal Laser Microscope Scanning Applied To Three-Dimensional Studies Of Biological Specimens.

    NASA Astrophysics Data System (ADS)

    Franksson, Olof; Liljeborg, Anders; Carlsson, Kjell; Forsgren, Per-Ola

    1987-08-01

    The depth-discriminating property of confocal laser microscope scanners can be used to record the three-dimensional structure of specimens. A number of thin sections (approx. 1 μm thick) can be recorded by a repeated process of image scanning and refocusing of the microscope. We have used a confocal microscope scanner in a number of feasibility studies to investigate its possibilities and limitations. It has proved to be well suited for examining fluorescent specimens with a complicated three-dimensional structure, such as nerve cells. It has also been used to study orchid seeds, as well as cell colonies, greatly facilitating evaluation of such specimens. Scanning of the specimens is performed by a focused laser beam that is deflected by rotating mirrors, and the reflected or fluorescent light from the specimen is detected. The specimen thus remains stationary during image scanning, and is only moved stepwise in the vertical direction for refocusing between successive sections. The scanned images consist of 256*256 or 512*512 pixels, each pixel containing 8 bits of data. After a scanning session a large number of digital images, representing consecutive sections of the specimen, are stored on a disk memory. In a typical case 200 such 256*256 images are stored. To display and process this information in a meaningful way requires both appropriate software and a powerful computer. The computer used is a 32-bits minicomputer equipped with an array processor (FPS 100). The necessary software was developed at our department.

  7. Solar cell evaluation using electron beam induced current with the large chamber scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Wink, Tara; Kintzel, Edward; Marienhoff, Peter; Klein, Martin

    2012-02-01

    An initial study using electron beam induced current (EBIC) to evaluate solar cells has been carried out with the large chamber scanning electron microscope (LC-SEM) at the Western Kentucky University Nondestructive Analysis Center. EBIC is a scanning electron microscope technique used for the characterization of semiconductors. To facilitate our studies, we developed a Solar Amplification System (SASY) for analyzing current distribution and defects within a solar cell module. Preliminary qualitative results will be shown for a solar cell module that demonstrates the viability of the technique using the LC-SEM. Quantitative EBIC experiments will be carried out to analyze defects and minority carrier properties. Additionally, a well-focused spot of light from an LED mounted at the side of the SEM column will scan the same area of the solar cell using the LC-SEM positioning system. SASY will then output the solar efficiency to be compared with the minority carrier properties found using EBIC.

  8. Low Temperature Scanning Tunneling Spectroscopy of isolated Mn12-Ph Single Molecule Magnets

    NASA Astrophysics Data System (ADS)

    Reaves, K.; Han, P.; Iwaya, K.; Hitosugi, T.; Packwood, D.; Katzgraber, H. G.; Zhao, H.; Dunbar, K. R.; Kim, K.; Teizer, W.

    2015-03-01

    We study Mn12O12(C6H5COO)16(H2O)4 (Mn12-Ph) single-molecule magnets on a Cu(111) surface using scanning tunneling microscopy and scanning tunneling spectroscopy at cryogenic temperatures (T < 6K). We report the observation of Mn12-Ph in isolation and in thin films, deposited through in situ vacuum spray deposition onto clean Cu(111). The tunneling current of isolated Mn12-Ph, normalized with respect to the Cu background, shows a strong bias voltage dependence within the molecular interior. The qualitative features of these I vs.V curves differ by spatial location in several intriguing ways (e.g. fixed junction impedance with increasing bias voltages). We explore these normalized I vs. V curves and present a phenomenological explanation for the observed behaviors, corresponding to the physical and electronic structure within the molecule. Funding from WPI-AIMR.

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

    ERIC Educational Resources Information Center

    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…

  10. Phase-gradient contrast in thick tissue with a scanning microscope

    PubMed Central

    Mertz, J.; Gasecka, A.; Daradich, A.; Davison, I.; Coté, D.

    2014-01-01

    It is well known that the principle of reciprocity is valid for light traveling even through scattering or absorptive media. This principle has been used to establish an equivalence between conventional widefield microscopes and scanning microscopes. We make use of this principle to introduce a scanning version of oblique back-illumination microscopy, or sOBM. This technique provides sub-surface phase-gradient and amplitude images from unlabeled tissue, in an epi-detection geometry. That is, it may be applied to arbitrarily thick tissue. sOBM may be implemented as a simple, cost-effective add-on with any scanning microscope, requiring only the availability of an extra input channel in the microscope electronics. We demonstrate here its implementation in combination with two-photon excited fluorescence (TPEF) microscopy and with coherent anti-Stokes Raman scattering (CARS) microscopy, applied to brain or spinal cord tissue imaging. In both cases, sOBM provides information on tissue morphology complementary to TPEF or CARS contrast. This information is obtained simultaneously and is automatically co-registered. Finally, we show that sOBM can be operated at video rate. PMID:24575336

  11. Characterization of grain boundary conductivity of spin-sprayed ferrites using scanning microwave microscope

    SciTech Connect

    Myers, J.; Nicodemus, T.; Zhuang, Y.; Watanabe, T.; Matsushita, N.; Yamaguchi, M.

    2014-05-07

    Grain boundary electrical conductivity of ferrite materials has been characterized using scanning microwave microscope. Structural, electrical, and magnetic properties of Fe{sub 3}O{sub 4} spin-sprayed thin films onto glass substrates for different length of growth times were investigated using a scanning microwave microscope, an atomic force microscope, a four-point probe measurement, and a made in house transmission line based magnetic permeameter. The real part of the magnetic permeability shows almost constant between 10 and 300 MHz. As the Fe{sub 3}O{sub 4} film thickness increases, the grain size becomes larger, leading to a higher DC conductivity. However, the loss in the Fe{sub 3}O{sub 4} films at high frequency does not increase correspondingly. By measuring the reflection coefficient s{sub 11} from the scanning microwave microscope, it turns out that the grain boundaries of the Fe{sub 3}O{sub 4} films exhibit higher electric conductivity than the grains, which contributes loss at radio frequencies. This result will provide guidance for further improvement of low loss ferrite materials for high frequency applications.

  12. Direct electron density modulation of surface plasmons with a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Saito, Yuika; Fujita, Katsumasa

    2015-01-01

    The optical properties of localized surface plasmon resonance (LSPR) were modulated by direct electron injection using scanning electron microscopy (SEM). The predictions of electromagnetic theory for LSPR on charged metal nanoparticles were experimentally verified using a novel microscopic system. Extinction spectra were obtained for gold nanostructures that were under intense electron irradiation using an SEM system equipped with an optical microscope. High-frequency shifts of LSPR were observed for a single gold nanosphere, nanodimer, and nanorod, and the amount of the shifts was explained with respect to their symmetry.

  13. Environmental scanning electron microscope (ESEM) evaluation of crystal and plaque formation associated with biocorrosion.

    PubMed

    Geiger, S L; Ross, T J; Barton, L L

    1993-08-01

    The biofilm attributed to Desulfovibrio vulgaris growing in the presence of ferrous metals was examined with an environmental scanning electron microscope. This novel microscope produced images of iron sulfide colloids and other iron containing structures that had not been reported previously. A plaque composed of iron sulfide enveloped the surface of the corroding metal while crystals containing magnesium, iron, sulfur, and phosphorus were present in the culture where corrosion was in progress. A structure resembling the tubercule found in aerobic corrosion was observed on stainless steel undergoing biocorrosion and the elements present in this structure included sulfur, iron, chloride, calcium, potassium, and chromium.

  14. Examination of silicon solar cells by means of the Scanning Laser Acoustic Microscope (SLAM)

    NASA Technical Reports Server (NTRS)

    Vorres, C.; Yuhas, D. E.

    1981-01-01

    The Scanning Laser Acoustic Microscope produces images of internal structure in materials. The acoustic microscope is an imaging system based upon acoustic rather than electromagnetic waves. Variations in the elastic propertis are primarily responsible for structure visualized in acoustic micrographs. The instrument used in these investigations is the SONOMICROSCOPE 100 which can be operated at ultrasonic frequencies of from 30 MHz to 500 MHz. The examination of the silicon solar cells was made at 100 MHz. Data are presented in the form of photomicrographs.

  15. Application of an ultrahigh-resolution scanning electron microscope (UHS-T1) to biological specimens.

    PubMed

    Tanaka, K; Mitsushima, A; Kashima, Y; Nakadera, T; Osatake, H

    1989-06-01

    In 1985 we developed an ultrahigh-resolution scanning electron microscope with a resolution of 0.5 nm. It is equipped with a field emission gun and an objective lens with a very short focal length. In this study we report a survey of some different preparation techniques and biological specimens using the new scanning electron microscope. Intracellular structures such as cell organelles were observed surprisingly sharper than those observed by ordinary scanning electron microscopes. However, at magnifications over 250,000 x, platinum particles could be discerned as scattered pebbles on the surface of all structures in coated materials. Using an uncoated but conductively stained specimen, we successfully observed ribosomes on a rough endoplasmic reticulum at a direct magnification of 1 million. In these images some protrusions were recognized on the ribosomes. Ferritin and immunoglobulin G were used as samples of biological macromolecules. These samples were observed without metal coating and conductive staining. The ferritin particles appeared as rounded bodies without any substructure on the surface and immunoglobulin G as complexes of three-unit bodies. In the latter the central body might correspond to the Fc fragment and two side ones to Fab fragments. We assume that ultrahigh-resolution scanning electron microscopy is an effective means for observation of the cell fine structures and biological macromolecules. It will open a new research field in biomedicine.

  16. Design and performance of the 2-ID-B scanning x-ray microscope.

    SciTech Connect

    McNulty, I.

    1998-11-11

    We have constructed a high resolution scanning x-ray microscope at the 2-ID-B beamline at the Advanced Photon Source for 1-4 keV x-ray imaging and microspectroscopy experiments. The microscope uses a Fresnel zone plate to focus coherent x-ray undulator radiation to a 150 nm focal spot on a sample. The spectral flux in the focus is 10{sup 8} ph/s/0.1% BW. X-ray photons transmitted by the sample are detected by an avalanche photodiode as the sample is scanned to form an absorption image. The sample stage has both coarse and fine translation axes for raster scanning and a rotation axis for microtomography experiments. The incident x-ray beam energy can also be scanned via the 2-ID-B monochromator while the sample is kept in focus to record spatially resolved absorption spectra. We have measured the performance of the instrument with various test objects. The microscope hardware, software, and performance are discussed in this paper.

  17. High-Resolution Scanning Tunneling Microscopy of Fully Hydrated Ripple-Phase Bilayers

    PubMed Central

    Woodward IV, J. T.; Zasadzinski, J. A.

    1997-01-01

    A modified freeze-fracture replication technique for use with the scanning tunneling microscope (STM) has provided a quantitative, high-resolution description of the waveform and amplitude of rippled bilayers in the Pβ, phase of dimyristoylphosphatidylcholine (DMPC) in excess water. The ripples are uniaxial and asymmetrical, with a temperature-dependent amplitude of 2.4 nm near the chain melting temperature that decreases to zero at the chain crystallization temperature. The wavelength of 11 nm does not change with temperature. The observed ripple shape and the temperature-induced structural changes are not predicted by any current theory. Calibration and reproducibility of the STM/replica technique were tested with replicas of well-characterized bilayers of cadmium arachidate on mica that provide regular 5.5-nm steps. STM images were analyzed using a cross-correlation averaging program to eliminate the effects of noise and the finite size and shapes of the metal grains that make up the replica. The correlation averaging allowed us to develop a composite ripple profile averaged over hundreds of individual ripples measured on different samples with different STM tips. The STM/replica technique avoids many of the previous artifacts of biological STM imaging and can be used to examine a variety of periodic hydrated lipid and protein samples at a lateral resolution of about 1 nm and a vertical resolution of about 0.3 nm. This resolution is superior to conventional and tapping mode AFM of soft biological materials; the technique is substrate-free, and the conductive and chemically uniform replicas make image interpretation simple and direct. ImagesFIGURE 1FIGURE 2FIGURE 3FIGURE 5 PMID:9017222

  18. Construction of a new type of low-energy scanning electron microscope with atomic resolution

    NASA Astrophysics Data System (ADS)

    Eastham, D. A.; Edmondson, P.; Donnelly, S.; Olsson, E.; Svensson, K.; Bleloch, A.

    2009-05-01

    We describe a new type of scanning electron microscope which works by directly imaging the electron field-emission sites on a nanotip. Electrons are extracted from the nanotip through a nanoscale aperture, accelerated in a high electric field and focussed to a spot using a microscale einzel lens. If the whole microscope (accelerating section and lens) and the focal length are both restricted in size to below 10 microns, then computer simulations show that the effects of aberration are extremely small and it is possible to have a system with approximately unit magnification, at electron energies as low as 300 eV. Thus a typical emission site of 1 nm diameter will produce an image of the same size and an atomic emission site with give a resolution of 0.1-0.2 nm (1-2 Å), and because the beam is not allowed to expand beyond 100nm in diameter the depth of field is large and the contribution to the beam spot size from chromatic aberrations is less than 0.02 nm (0.2 Å) for 500 eV electrons. Since it is now entirely possible to make stable atomic sized emitters (nanopyramids) it is expected that this instrument will have atomic resolution. Furthermore the brightness of the beam is determined only by the field-emission and can be up to a million times larger than in a typical (high-energy) electron microscope. The construction of this microscope, based on using a nanotip electron source which is mounted on a nanopositioner so that it can be positioned at the correct point adjacent to the microscope, entrance aperture, is described. In this geometry the scanning is achieved by moving the sample using piezos. Two methods for the construction of the microscope column are reviewed and the results of preliminary tests are described. The advantages of this low energy, bright-beam, electron microscope with atomic resolution are described. It can be used in either scanning mode or diffraction mode. The major advantage over existing microscopes is that because it works at very low

  19. Superconducting scanning tunneling microscopy tips in a magnetic field: Geometry-controlled order of the phase transition

    SciTech Connect

    Eltschka, Matthias Jäck, Berthold; Assig, Maximilian; Etzkorn, Markus; Ast, Christian R.; Kondrashov, Oleg V.; Skvortsov, Mikhail A.; Kern, Klaus

    2015-09-21

    The properties of geometrically confined superconductors significantly differ from their bulk counterparts. Here, we demonstrate the geometrical impact for superconducting scanning tunneling microscopy (STM) tips, where the confinement ranges from the atomic to the mesoscopic scale. To this end, we compare the experimentally determined magnetic field dependence for several vanadium tips to microscopic calculations based on the Usadel equation. For our theoretical model of a superconducting cone, we find a direct correlation between the geometry and the order of the superconducting phase transition. Increasing the opening angle of the cone changes the phase transition from first to second order. Comparing our experimental findings to the theory reveals first and second order quantum phase transitions in the vanadium STM tips. In addition, the theory also explains experimentally observed broadening effects by the specific tip geometry.

  20. An ultra-low temperature scanning Hall probe microscope for magnetic imaging below 40 mK.

    PubMed

    Karcı, Özgür; Piatek, Julian O; Jorba, Pau; Dede, Münir; Rønnow, Henrik M; Oral, Ahmet

    2014-10-01

    We describe the design of a low temperature scanning Hall probe microscope (SHPM) for a dilution refrigerator system. A detachable SHPM head with 25.4 mm OD and 200 mm length is integrated at the end of the mixing chamber base plate of the dilution refrigerator insert (Oxford Instruments, Kelvinox MX-400) by means of a dedicated docking station. It is also possible to use this detachable SHPM head with a variable temperature insert (VTI) for 2 K-300 K operations. A microfabricated 1μm size Hall sensor (GaAs/AlGaAs) with integrated scanning tunneling microscopy tip was used for magnetic imaging. The field sensitivity of the Hall sensor was better than 1 mG/√Hz at 1 kHz bandwidth at 4 K. Both the domain structure and topography of LiHoF4, which is a transverse-field Ising model ferromagnet which orders below TC = 1.53 K, were imaged simultaneously below 40 mK.

  1. A novel high-throughput scanning microscope for label-free detection of protein and small-molecule chemical microarrays

    PubMed Central

    Fei, Y.Y.; Landry, J.P.; Sun, Y.S.; Luo, J.T.; Wang, X.B.; Lam, K.S; Zhu, X.D.

    2009-01-01

    We describe a novel scanning optical microscope based on a polarization-modulated nulling ellipsometry. The new microscope employs a combination of scanning mirror and sample translation and thus enables high-throughput label-free detection of biomolecular microarrays with more than 10,000 protein or small molecule targets. For illustration, we show the image of a 2760-spot protein microarray on a functionalized glass slide obtained with such a microscope. The new scanning microscope is also capable of determining, in parallel, the real-time binding kinetics of multiple molecular species under aqueous conditions. PMID:18248040

  2. Compact multiphoton/single photon laser scanning microscope for spectral imaging and fluorescence lifetime imaging.

    PubMed

    Ulrich, Volker; Fischer, Peter; Riemann, Iris; Königt, Karsten

    2004-01-01

    An inverted fluorescence microscope was upgraded into a compact three-dimensional laser scanning microscope (LSM) of 65 x 62 x 48 cm dimensions by means of a fast kHz galvoscanner unit, a piezodriven z-stage, and a picosecond (ps) 50 MHz laser diode at 405 nm. In addition, compact turn-key near infrared femtosecond lasers have been employed to perform multiphoton fluorescence and second harmonic generation (SHG) microscopy. To expand the features of the compact LSM, a time-correlated single photon counting unit as well as a Sagnac interferometer have been added to realize fluorescence lifetime imaging (FLIM) and spectral imaging. Using this unique five-dimensional microscope, TauMap, single-photon excited (SPE), and two-photon excited (TPE) cellular fluorescence as well as intratissue autofluorescence of water plant leaves have been investigated with submicron spatial resolution, <270 ps temporal resolution, and 10 nm spectral resolution. PMID:15536977

  3. Tip alignment system in a sextupole-corrected scanning transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Ruan, Shengyang; Kapp, Oscar H.

    1993-03-01

    Tip alignment and replacement in ultrahigh vacuum field-emission electron microscopes is traditionally a time-consuming endeavor. A convenient autodrive system for the 200 kV scanning transmission electron microscope was developed to facilitate the alignment of field-emission tips, thus saving a great deal of experimenter time. Under computer control, a series of automatic electrical and mechanical processes are initiated to systematically adjust various parameters to effect passage of the electron beam through the various apertures of the microscope column. The task of ``finding the beam'' is thus performed automatically. In this process the tip holder is moved in a raster parallel to the first anode. Feedback from various detectors placed throughout the column direct the positioning of the tip for optimal alignment. This process is routinely performed in about 45 min.

  4. Assessing the structure and function of single biomolecules with scanning transmission electron and atomic force microscopes.

    PubMed

    Müller, Shirley A; Müller, Daniel J; Engel, Andreas

    2011-02-01

    The scanning transmission electron microscope (STEM) and the atomic force microscope (AFM) have provided a wealth of useful information on a wide variety of biological structures. These instruments have in common that they raster-scan a probe over a sample and are able to address single molecules. In the STEM the probe is a focused electron beam that is deflected by the scan-coils. Detectors collecting the scattered electrons provide quantitative information for each sub-nanometer sized sample volume irradiated. These electron scattering data can be reconstituted to images of single macromolecules or can be integrated to provide the mass of the macromolecules. Samples need to be dehydrated for such quantitative STEM imaging. In contrast, the AFM raster-scans a sharp tip over a sample surface submerged in a buffer solution to acquire information on the sample's surface topography at sub-nanometer resolution. Direct observation of function-related structural changes induced by variation of temperature, pH, ionic strength, and applied force provides insight into the structure-function relationship of macromolecules. Further, the AFM allows single molecules to be addressed and quantitatively unfolded using the tip as nano-tweezers. The performance of these two scanning probe approaches is illustrated by several examples including the chaperonin GroEL, bacterial surface layers, protein crystals, and bacterial appendices.

  5. Development of a Hybrid Atomic Force Microscopic Measurement System Combined with White Light Scanning Interferometry

    PubMed Central

    Guo, Tong; Wang, Siming; Dorantes-Gonzalez, Dante J.; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2012-01-01

    A hybrid atomic force microscopic (AFM) measurement system combined with white light scanning interferometry for micro/nanometer dimensional measurement is developed. The system is based on a high precision large-range positioning platform with nanometer accuracy on which a white light scanning interferometric module and an AFM head are built. A compact AFM head is developed using a self-sensing tuning fork probe. The head need no external optical sensors to detect the deflection of the cantilever, which saves room on the head, and it can be directly fixed under an optical microscopic interferometric system. To enhance the system’s dynamic response, the frequency modulation (FM) mode is adopted for the AFM head. The measuring data can be traceable through three laser interferometers in the system. The lateral scanning range can reach 25 mm × 25 mm by using a large-range positioning platform. A hybrid method combining AFM and white light scanning interferometry is proposed to improve the AFM measurement efficiency. In this method, the sample is measured firstly by white light scanning interferometry to get an overall coarse morphology, and then, further measured with higher resolution by AFM. Several measuring experiments on standard samples demonstrate the system’s good measurement performance and feasibility of the hybrid measurement method. PMID:22368463

  6. Glass for parenteral products: a surface view using the scanning electron microscope.

    PubMed

    Roseman, T J; Brown, J A; Scothorn, W W

    1976-01-01

    The scanning electron microscope was utilized to explore the internal surface of glass ampuls and vials used in parenteral products. The surface topography of USP Type I borosilicate glass containers was viewed after exposure to "sulfur," ammonium bifluoride, and sulfuric acid treatments. The scanning electron micrographs showed startling differences in the appearance of the surface regions. "Sulfur treatment" of ampuls was associated with a pitting of the surface and the presence of sodium sulfate crystals. The sulfur treatment of vials altered the glass surface in a characteristically different manner. The dissimilarity between the surface appearances was attributed to the method of sulfur treatment. Ampuls exposed to sulfuric acid solutions at room temperature did not show the pitting associated with the sulfur treatment. Scanning electron micrographs of ammonium bifluoride-treated ampuls showed a relief effect, suggesting that the glass was affected by the bifluoride solution but that sufficient stripping of the surface layer did not occur to remove the pits associated with the sulfur treatment. Flakes emanating from the glass were identified with the aid of the electron microprobe. Scanning electron micrographs showed that these vitreous flakes resulted from a delamination of a thin layer of the glass surface. It is concluded that the scanning electron microscope, in conjunction with other analytical techniques, is a valuable tool in assessing the quality of glass used for parenteral products. The techniques studied should be of particular importance to the pharmaceutical industry where efforts are being made to reduce the levels of particulate matter in parenteral dosage forms.

  7. Development of a hybrid atomic force microscopic measurement system combined with white light scanning interferometry.

    PubMed

    Guo, Tong; Wang, Siming; Dorantes-Gonzalez, Dante J; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2012-01-01

    A hybrid atomic force microscopic (AFM) measurement system combined with white light scanning interferometry for micro/nanometer dimensional measurement is developed. The system is based on a high precision large-range positioning platform with nanometer accuracy on which a white light scanning interferometric module and an AFM head are built. A compact AFM head is developed using a self-sensing tuning fork probe. The head need no external optical sensors to detect the deflection of the cantilever, which saves room on the head, and it can be directly fixed under an optical microscopic interferometric system. To enhance the system's dynamic response, the frequency modulation (FM) mode is adopted for the AFM head. The measuring data can be traceable through three laser interferometers in the system. The lateral scanning range can reach 25 mm × 25 mm by using a large-range positioning platform. A hybrid method combining AFM and white light scanning interferometry is proposed to improve the AFM measurement efficiency. In this method, the sample is measured firstly by white light scanning interferometry to get an overall coarse morphology, and then, further measured with higher resolution by AFM. Several measuring experiments on standard samples demonstrate the system's good measurement performance and feasibility of the hybrid measurement method.

  8. Detection of Luminescent Nanodiamonds Using a Scanning Near-Field Optical Microscope with an Aperture Probe

    NASA Astrophysics Data System (ADS)

    Shershulin, V. A.; Samoylenko, S. R.; Shenderova, O. A.; Vlasov, I. I.; Konov, V. I.

    2016-09-01

    Scanning near-fi eld optical microscopy (SNOM) with an aperture probe has been used to map the luminescence of isolated submicron diamond crystallites. 532-nm laser light was used to excite luminescence of nitrogen-vacancy (NV) centers. The sizes of the analyzed diamond crystallites were determined with an atomic-force microscope. The optical resolution for the lateral dimensions of the luminescing diamond crystallites was doubled on going from confocal luminescence microscopy to scanning near-fi eld optical microscopy with a 290-nm probe aperture diameter.

  9. Design of a scanning gate microscope in a cryogen-free dilution refrigerator

    NASA Astrophysics Data System (ADS)

    Pelliccione, Matthew; Sciambi, Adam; Goldhaber-Gordon, David

    2011-03-01

    We report on our design of an ultra-low temperature scanning gate microscope housed in a system with no liquid helium bath. The recent increase in efficiency of pulse-tube cryocoolers and pending scarcity of liquid helium have made ``cryogen-free'' dewars popular in recent years. However, this new style of dewar presents challenges for performing scanning measurements, most notably the increased vibrations introduced by the cryocooler. We will highlight the tradeoffs made in choosing such a system to house a scanner, and describe our efforts to achieve a stability suitable for measurements on mesoscopic systems.

  10. Magnetic field imaging of a tungsten carbide film by scanning nano-SQUID microscope

    NASA Astrophysics Data System (ADS)

    Shibata, Yusuke; Nomura, Shintaro; Ishiguro, Ryosuke; Kashiwaya, Hiromi; Kashiwaya, Satoshi; Nago, Yusuke; Takayanagi, Hideaki

    2016-10-01

    We present the results of magnetic field imaging by scanning nano-superconducting quantum interference device (SQUID) microscopy on a tungsten carbide (W-C) film fabricated using focused-ion-beam chemical vapor deposition. We have investigated magnetic field change by a W-C film in an external magnetic field using a scanning nano-SQUID microscope system. We have found that the reduction of the magnetic field above the W-C film was 0.9%, indicating the penetration of vortices in the W-C at an external magnetic field of 0.171 mT.

  11. Development of a scanning nanopipette probe microscope for fine processing using atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Morimatsu, Daisuke; Sugimoto, Hiromitsu; Nakamura, Atsushi; Ogino, Akihisa; Nagatsu, Masaaki; Iwata, Futoshi

    2016-08-01

    We developed a novel technique for fine material processing based on a localized atmospheric-pressure plasma jet (APPJ) using a scanning probe microscope equipped with a nanopipette. Using a nanopipette — a tapered glass capillary with an aperture of sub-micrometer diameter — as a nozzle makes it possible to localize the discharge area of the APPJ for fine surface processing. The nanopipette can also be used as a probe for a scanning probe microscope operated with shear-force feedback control, which is capable of positioning the pipette edge in the vicinity of material surfaces for APPJ processing and imaging of the processed surface. Sub-micrometer holes and line patterns were successfully processed on a photoresist film. It was possible to control the size of the processed patterns by varying the applied pulse voltage and the distance between the pipette and the surface.

  12. Imaging of current density distributions with a Nb weak-link scanning nano-SQUID microscope

    PubMed Central

    Shibata, Yusuke; Nomura, Shintaro; Kashiwaya, Hiromi; Kashiwaya, Satoshi; Ishiguro, Ryosuke; Takayanagi, Hideaki

    2015-01-01

    Superconducting quantum interference devices (SQUIDs) are accepted as one of the highest magnetic field sensitive probes. There are increasing demands to image local magnetic fields to explore spin properties and current density distributions in a two-dimensional layer of semiconductors or superconductors. Nano-SQUIDs have recently attracting much interest for high spatial resolution measurements in nanometer-scale samples. Whereas weak-link Dayem Josephson junction nano-SQUIDs are suitable to miniaturization, hysteresis in current-voltage (I-V) characteristics that is often observed in Dayem Josephson junction is not desirable for a scanning microscope. Here we report on our development of a weak-link nano-SQUIDs scanning microscope with small hysteresis in I-V curve and on reconstructions of two-dimensional current density vector in two-dimensional electron gas from measured magnetic field. PMID:26459874

  13. Depth Sectioning with the Aberration-Corrected Scanning Transmission Electron Microscope

    SciTech Connect

    Borisevich, Albina Y; Lupini, Andrew R; Pennycook, Stephen J

    2006-01-01

    The ability to correct the aberrations of the probe-forming lens in the scanning transmission electron microscope provides not only a significant improvement in transverse resolution but in addition brings depth resolution at the nanometer scale. Aberration correction therefore opens up the possibility of 3D imaging by optical sectioning. Here we develop a definition for the depth resolution for scanning transmission electron microscope depth sectioning and present initial results from this method. Objects such as catalytic metal clusters and single atoms on various support materials are imaged in three dimensions with a resolution of several nanometers. Effective focal depth is determined by statistical analysis and the contributing factors are discussed. Finally, current challenges and future capabilities available through new instruments are discussed.

  14. Scanning tunnelling spectroscopy and Raman spectroscopy of monolayer silicene on Ag(111)

    NASA Astrophysics Data System (ADS)

    Díaz Álvarez, A.; Zhu, T.; Nys, J. P.; Berthe, M.; Empis, M.; Schreiber, J.; Grandidier, B.; Xu, T.

    2016-11-01

    Low temperature scanning tunnelling spectroscopy and Raman spectroscopy were used to study the electronic and vibrational properties of silicene formed on the Ag(111) surface for coverage up to one monolayer in the temperature range 230-250 °C. The tunnelling spectra reveal the strong contribution of silver states in the measured density of states around the Fermi level. The Raman spectra are found to evolve as a function of the submonolayer coverages, giving rise at one monolayer coverage to peaks that are characteristic of chemical bonds with distorted sp3 hybrid orbitals. Such properties account for the electronic transparency of the silicene/Ag(111) interface.

  15. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P.; Chernobrod, Boris M.

    2007-12-11

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  16. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P.; Chernobrod, Boris M.

    2010-06-29

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  17. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P.; Chernobrod, Boris M.

    2010-07-13

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  18. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P.; Chernobrod, Boris M.

    2009-10-27

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  19. Spin microscope based on optically detected magnetic resonance

    SciTech Connect

    Berman, Gennady P.; Chernobrod, Boris M.

    2009-11-10

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of impaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  20. A method for visualizing cytoskeletal structures by the scanning electron microscope.

    PubMed

    Takahashi, I; Amakawa, Y

    1989-01-01

    The cytoskeleton of intestinal epithelial cells was observed by scanning electron microscope (SEM). Tissues were treated with Triton X-100, stained to enhance conductivity, and freeze-fractured in liquid nitrogen. With these procedures, not only the localization of core filaments (actin-containing microfilaments) and intermediate filaments but also the relations between fibrous structures and cell organellae were clearly revealed. This conventional method is of great value in interpreting the three-dimensional organization of intracellular fine structures. PMID:2809464

  1. Differential phase microscope and micro-tomography with a Foucault knife-edge scanning filter

    NASA Astrophysics Data System (ADS)

    Watanabe, N.; Hashizume, J.; Goto, M.; Yamaguchi, M.; Tsujimura, T.; Aoki, S.

    2013-10-01

    An x-ray differential phase microscope with a Foucault knife-edge scanning filter was set up at the bending magnet source BL3C, Photon Factory. A reconstructed phase profile from the differential phase image of an aluminium wire at 5.36 keV was fairly good agreement with the numerical simulation. Phase tomography of a biological specimen, such as an Artemia cyst, could be successfully demonstrated.

  2. Defect tracking for nanoimprint lithography using optical surface scanner and scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Yu, Zhaoning; Kurataka, Nobuo; Tran, Hieu; Gauzner, Gene

    2016-09-01

    Fast optical surface scanners are used in combination with high-resolution scanning electron microscopes to facilitate the identification and tracking of nanoimprint defects. We have confirmed that hard particles cause permanent template damages during imprint, resulting in repeating imprint defects. Since contaminants encountered during imprint are dominated by hard metal oxide particles capable of causing such damage, stringent pre-imprint substrate screening is a critical requirement in a manufacturing environment.

  3. Simultaneous imaging of multiple focal planes using a two-photon scanning microscope

    NASA Astrophysics Data System (ADS)

    Amir, W.; Carriles, R.; Hoover, E. E.; Planchon, T. A.; Durfee, C. G.; Squier, J. A.

    2007-06-01

    Despite all the advances in nonlinear microscopy, all existing instruments are constrained to obtain images of one focal plane at a time. In this Letter we demonstrate a two-photon absorption fluorescence scanning microscope capable of imaging two focal planes simultaneously. This is accomplished by temporally demultiplexing the signal coming from two focal volumes at different sample depths. The scheme can be extended to three or more focal planes.

  4. David Maurice's contributions to optical ophthalmic instrumentation: roots of the scanning slit clinical confocal microscope.

    PubMed

    Masters, Barry R

    2004-03-01

    This paper explores the seminal contributions of David Maurice to the field of ophthalmic instrumentation. His development of the specular microscope, the scanning slit optical confocal microscope, and the corneal microfluorometer resulted in advances in our understanding of corneal morphology, physiology, and pathology. The development of the scanning slit, clinical confocal microscope is not a new paradigm or a paradigm shift, but a continuous series of interlinked technical advances from the early work of Vogt to Thaer's development of a clinical confocal microscope. For each instrument both the connection to the prior work of others and the unique advances are discussed and contrasted. This paper develops the connections and parallel developments in the instrument developments of Goldmann, Maurice, Svishchev, Baer, Koester, Masters, and Thaer. The evidence in support of the thesis consists of published papers, patents, personal communication, and study of Goldmann's book collection in Bern. A second theme is that knowledge of physics is a prerequisite for optical instrument development in ophthalmology. David Maurice had a university degree in physics and Hans Goldmann learned physics from his books. The contributions of David Maurice to optical instrumentation follow the major contributions of Goldmann and facilitated and stimulated other scientists who acknowledged their important intellectual debt to David Maurice.

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

    PubMed

    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. PMID:26724038

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

    SciTech Connect

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

    2015-12-15

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

  7. Obtaining Vector Magnetic Field Maps of Geological Samples with Single-Axis Scanning Magnetic Microscopes

    NASA Astrophysics Data System (ADS)

    Lima, E. A.; Weiss, B. P.

    2008-12-01

    Magnetic scanning microscopy can be used to study inhomogeneous magnetization in geological samples with submillimiter spatial resolution. In particular, Superconducting Quantum Interference Device (SQUID) microscopes offer a unique combination of high spatial resolution and outstanding field sensitivity. However, due to physical constraints, most magnetic microscopes only measure a single component of the magnetic field. Nevertheless, Maxwell's equations can be used to demonstrate that the components of a static magnetic field in a region of space devoid of sources are not independent. This means that single-axis scanning magnetometers can potentially obtain all of three components of the field external to the sample. We present an improved technique in the Fourier domain which can obtain the complete vector field planar map from just the planar map of one component. This technique is fast, robust, does not rely on any specific source type or configuration and does not require the formulation of an inverse problem. In contrast to other applications in geomagnetic remote sensing, the assumptions and conditions imposed on the field distribution by the technique can be naturally satisfied in scanning microscopy of geological samples. We analyze the advantages and shortcomings of the technique, and establish which sensor and mapping configurations may yield high quality three-component field maps with virtually no information loss. We present results obtained both with synthetic data and experimental data measured with our SQUID microscope system.

  8. Carbon-fiber tips for scanning probe microscopes and molecular electronics experiments.

    PubMed

    Rubio-Bollinger, Gabino; Castellanos-Gomez, Andres; Bilan, Stefan; Zotti, Linda A; Arroyo, Carlos R; Agraït, Nicolás; Cuevas, Juan Carlos

    2012-01-01

    We fabricate and characterize carbon-fiber tips for their use in combined scanning tunneling and force microscopy based on piezoelectric quartz tuning fork force sensors. An electrochemical fabrication procedure to etch the tips is used to yield reproducible sub-100-nm apex. We also study electron transport through single-molecule junctions formed by a single octanethiol molecule bonded by the thiol anchoring group to a gold electrode and linked to a carbon tip by the methyl group. We observe the presence of conductance plateaus during the stretching of the molecular bridge, which is the signature of the formation of a molecular junction.

  9. A Novel Scanning Near-Field Microwave Microscope Capable of High Resolution Loss Imaging

    NASA Astrophysics Data System (ADS)

    Imtiaz, Atif; Anlage, Steven

    2004-03-01

    To study novel physics in condensed matter and materials science, experimental techniques need to be pushed to the limit of better sensitivity and higher spatial resolution. Classical techniques of probing the high frequency electrical properties of materials are limited in resolution to the wavelength of the incident electromagnetic wave. We report here a novel near-field microscope that is capable of operation at radio and microwave frequencies[1]. These experiments are performed with a version of the near-field microwave microscope that has integrated STM-feedback for distance control. When used in the scanning capacitance mode this instrument has a spatial resolution of 2.5 nm. Our objective is to image materials contrast at microwave frequencies and improve the spatial resolution in local loss imaging. We will present evidence of sheet resistance contrast in a Boron-doped Silicon samples on sub-micron length scales. We will present quantitative analysis of the data in light of transmission line and lumped element models of the microscope that we have developed. The microscope is an attractive platform for measuring local losses and local nonlinear properties of a rich variety of condensed matter systems, such as correlated-electron systems. [1] Atif Imtiaz and Steven M. Anlage, "A novel STM-assisted microwave microscope with capacitance and loss imaging capability", Ultramicroscopy 94, 209-216 (2003).

  10. Momentum-dependent scanning tunneling spectroscopy in MgB{sub 2}.

    SciTech Connect

    Karapetrov, G.; Iavarone, M.; Koshelev, A. E.; Kwok, W. K.; Crabtree, G. W.; Hinks, D. G.; Lee, S. I.

    2002-07-31

    We present study of the anisotropic superconductor MgB{sub 2} using a combination of scanning tunneling microscopy and spectroscopy. The results reveal two distinct energy gaps at {Delta}{sub 1} = 2.3 meV and {Delta}{sub 2} = 7.1 meV. Different spectral weights of the partial superconducting density of states are a reflection of different tunneling directions in this multi-band system. Our experimental observations are consistent with the existence of two-band superconductivity in the presence of interband superconducting pair interaction and quasiparticle scattering. Temperature evolution of the tunneling spectra follows the BCS scenario with both gaps vanishing at the bulk T{sub c}. The data confirm the importance of Fermi-surface sheet dependent superconductivity in MgB{sub 2} proposed in the multigap model by Liu et al. [1].

  11. Quantitative determination of local potential values in inhomogeneously doped semiconductors by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Weidlich, P. H.; Dunin-Borkowski, R. E.; Ebert, Ph.

    2011-08-01

    Local potential changes arising from nanoscale three-dimensional spatial fluctuations in the dopant distribution in Zn-doped GaAs were investigated quantitatively by scanning tunneling microscopy and spectroscopy at (110) cleavage surfaces. Tunneling spectra measured in areas with different local doping concentration show apparent shifts of the valence band edge and apparent changes of the band gap. A quantitative analysis, combined with band bending and tunnel current simulations, demonstrates that these effects arise from tip-induced band bending that modulates the real potential changes. It is illustrated how exact potential changes between locally high and low doped areas can be determined. It is found that the local potential fluctuations in three-dimensionally doped semiconductors are approximately one order of magnitude smaller that those observed in two-dimensionally doped semiconductors.

  12. Method and apparatus for a high-resolution three dimensional confocal scanning transmission electron microscope

    DOEpatents

    de Jonge, Niels [Oak Ridge, TN

    2010-08-17

    A confocal scanning transmission electron microscope which includes an electron illumination device providing an incident electron beam propagating in a direction defining a propagation axis, and a precision specimen scanning stage positioned along the propagation axis and movable in at least one direction transverse to the propagation axis. The precision specimen scanning stage is configured for positioning a specimen relative to the incident electron beam. A projector lens receives a transmitted electron beam transmitted through at least part of the specimen and focuses this transmitted beam onto an image plane, where the transmitted beam results from the specimen being illuminated by the incident electron beam. A detection system is placed approximately in the image plane.

  13. Critical current density measurement of striated multifilament-coated conductors using a scanning Hall probe microscope

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Fen; Kochat, Mehdi; Majkic, Goran; Selvamanickam, Venkat

    2016-08-01

    In this paper the authors succeeded in measuring the critical current density ({J}{{c}}) of multifilament-coated conductors (CCs) with thin filaments as low as 0.25 mm using the scanning hall probe microscope (SHPM) technique. A new iterative method of data analysis is developed to make the calculation of {J}{{c}} for thin filaments possible, even without a very small scan distance. The authors also discussed in detail the advantage and limitation of the iterative method using both simulation and experiment results. The results of the new method correspond well with the traditional fast Fourier transform method where this is still applicable. However, the new method is applicable for the filamentized CCs in much wider measurement conditions such as with thin filament and a large scan distance, thus overcoming the barrier for application of the SHPM technique on {J}{{c}} measurement of long filamentized CCs with narrow filaments.

  14. Measurements Using a Scanning Near-Field Coaxial Probe Microwave Microscope

    NASA Astrophysics Data System (ADS)

    Steinhauer, David E.; Vlahacos, C. P.; Dutta, Sudeep; Wellstood, F. C.; Anlage, Steven M.

    1997-03-01

    We have developed a scanning near-field microwave microscope using an open-ended coaxial probe.(C. P. Vlahacos, et al.) Appl. Phys. Lett. 69, 3272 (1996)^,(S. M. Anlage, et al.) IEEE Trans. Appl. Supercond. (1997) The probe is connected to a coaxial transmission line, which acts as a resonant microwave circuit. The probe is scanned over a sample while microwave energy is fed into the other end of the coaxial line. The quantities that can be measured simultaneously during a scan are shifts in the resonant frequencies, amplitude of the resonant peaks, quality factor of the circuit, and changes in phase relative to the microwave source. We will show images and discuss the theory of how the data are related to properties of the sample.

  15. Scanning transmission x-ray microscope for materials science spectromicroscopy at the ALS

    SciTech Connect

    Warwick, T.; Seal, S.; Shin, H.

    1997-04-01

    The brightness of the Advanced Light Source will be exploited by several new instruments for materials science spectromicroscopy over the next year or so. The first of these to become operational is a scanning transmission x-ray microscope with which near edge x-ray absorption spectra (NEXAFS) can be measured on spatial features of sub-micron size. Here the authors describe the instrument as it is presently implemented, its capabilities, some studies made to date and the developments to come. The Scanning Transmission X-ray Microscope makes use of a zone plate lens to produce a small x-ray spot with which to perform absorption spectroscopy through thin samples. The x-ray beam from ALS undulator beamline 7.0 emerges into the microscope vessel through a silicon nitride vacuum window 160nm thick and 300{mu}m square. The vessel is filled with helium at atmospheric pressure. The zone plate lens is illuminated 1mm downstream from the vacuum window and forms an image in first order of a pinhole which is 3m upstream in the beamline. An order sorting aperture passes the first order converging light and blocks the unfocused zero order. The sample is at the focus a few mm downstream of the zone plate and mounted from a scanning piezo stage which rasters in x and y so that an image is formed, pixel by pixel, by an intensity detector behind the sample. Absorption spectra are measured point-by-point as the photon energy is scanned by rotating the diffraction grating in the monochromator and changing the undulator gap.

  16. The geometry of nanometer-sized electrodes and its influence on electrolytic currents and metal deposition processes in scanning tunneling and scanning electrochemical microscopy

    NASA Astrophysics Data System (ADS)

    Sklyar, Oleg; Treutler, Thomas H.; Vlachopoulos, Nikolaos; Wittstock, Gunther

    2005-12-01

    Electrodes with an effective radius of about 10 nm have been produced by a combination of electrochemical etching, electrophoretic deposition of polymer, and heat curing. Their size and stability were characterized by cyclic voltammetry. They were then used in combined electrochemical scanning tunneling microscopic (ECSTM) and scanning electrochemical microscopic (SECM) experiments. In an extension of an earlier report, electrochemical surface modification approaches are reported here. They comprise the local electrochemical removal of a self-assembled monolayer (SAM) of dodecanethiol on flame-annealed gold by an electrochemical desorption procedure. The possibility of local electrochemical deposition is demonstrated by positioning a nanoelectrode 0.5 nm above a surface and switching off the distance regulation while performing an electrodeposition of Pt at the tip. The growing deposit bridges the tip-sample gap. If the distance regulation is switched on after 1 ms, the Pt junction is disrupted leaving a Pt nanodot at the sample surface. The dot was characterized by ECSTM experiments after solution exchange. Digital simulations by the boundary element method (BEM) provide a quantitative description of Faraday currents in nanoelectrochemical assemblies. A software tool was created that can accept arbitrary geometries as input data sets. The flexibility of the simulation strategy was demonstrated by the calculation of local current densities during electrochemical copper deposition on a smooth electrode in the presence of an ECSTM tip close to the surface. The current densities deviate less than 1% from those in the absence of tip if the average current density is kept below 1 μA cm -2. SECM approach curves for nanoelectrodes were also calculated.

  17. Note: Fabrication and characterization of molybdenum tips for scanning tunneling microscopy and spectroscopy

    SciTech Connect

    Carrozzo, P.; Tumino, F.; Facibeni, A.; Passoni, M.; Casari, C. S.; Li Bassi, A.

    2015-01-15

    We present a method for the preparation of bulk molybdenum tips for Scanning Tunneling Microscopy and Spectroscopy and we assess their potential in performing high resolution imaging and local spectroscopy by measurements on different single crystal surfaces in UHV, namely, Au(111), Si(111)-7 × 7, and titanium oxide 2D ordered nanostructures supported on Au(111). The fabrication method is versatile and can be extended to other metals, e.g., cobalt.

  18. Scanning tunneling microscopy of chromium-filled carbon nanotubes: Tip effects and related topographic features

    NASA Astrophysics Data System (ADS)

    Zha, F.-X.; Czerw, R.; Carroll, D. L.; Kohler-Redlich, Ph.; Wei, B.-Q.; Loiseau, A.; Roth, S.

    2000-02-01

    We have used ultrahigh vacuum scanning tunneling microscopy (STM) to study chromium (Cr)-filled carbon nanotubes. STM micrographs show filled tubes to be less than 1 nm in height, while transmission electron microscopy indicates that Cr-filled naotubes are multiwalled with diameters generally over 10 nm. In this paper, we demonstrate that the small apparent heights are due to the STM tip status, which also accounts for the topographic anomalies observed.

  19. Single pentagon in a hexagonal carbon lattice revealed by scanning tunneling microscopy

    SciTech Connect

    An, B.; Fukuyama, S.; Yokogawa, K.; Yoshimura, M.; Egashira, M.; Korai, Y.; Mochida, I.

    2001-06-04

    The electronic structure of a single pentagon in a hexagonal carbon lattice has been revealed on an atomic scale by scanning tunneling microscopy. The pentagon is located at the apex of the conical protuberance of the graphitic particle. The enhanced charge density localized at each carbon atom in the pentagon is identified, and the ringlike pattern of the ({radical}3{times}{radical}3)R30{degree} superstructure of graphite is clearly observed around the pentagon. {copyright} 2001 American Institute of Physics.

  20. A scanning and transmission electron microscopic analysis of the cerebral aqueduct in the rabbit.

    PubMed

    Meller, S T; Dennis, B J

    1993-09-01

    An examination of the surface of the cerebral aqueduct with the scanning electron microscope revealed that the walls of the cerebral aqueduct were so heavily ciliated that most of the ependymal surface was obscured, yet certain specialized supraependymal structures could be discerned lying on (or embedded within) this matt of cilia. These structures were determined by transmission electron microscopy and Golgi analysis to be either macrophages, supraependymal neurons, dendrites from medial periaqueductal gray neurons, or axons of unknown origin. Some axons, which were found to contain vesicles, appeared to make synaptic contacts with ependymal cells. Using the transmission electron microscope, the ependymal lining was found to consist of two different cell types: normal ependymal cells and tanycytes which have a long tapering basal process that was observed to contact blood vessels or, more rarely, seemed to terminate in relation to neuronal elements. While there have been previous reports on the structure of the third and lateral ventricles in other species, there are limited reports in the rabbit. The present report is not only the first description for the rabbit, but it is the first complete scanning and transmission electron microscopic analysis of the cerebral aqueduct in any species.

  1. Image Tracking of Multiple C. Elegans Worms Using Adaptive Scanning Optical Microscope (ASOM)

    NASA Astrophysics Data System (ADS)

    Rivera, Linda; Potsaid, Benjamin; Wen, John T.

    2010-03-01

    Long-term imaging of living biological specimens is important to infer behaviorial trends and correlate neural structure with behavior. Such study is plagued by the field of view limitation in standard optical microscopes, as the motile specimen would frequently move out of view. A novel microscope, called the adaptive scanning optical microscope (ASOM), has recently been proposed to address this limitation. Through high speed post-objective scanning with a steering mirror, and compensation for optical aberrations with a MEMS deformable mirror, simultaneous imaging and tracking of multiple Caenorhabditis elegans worms has been demonstrated. This article presents the image processing algorithm for tracking multiple worms. Since the steering mirror has to move based on the predicted worm motion, image processing and stable steering mirror motion need to be executed at higher than the composite mosaic video frame rate (in contrast to existing works on image-based worm tracking, which are predominantly based on post-processing). Particular care is placed on disambiguating the worms when they overlap, collide, or entangle, where the worm tracking algorithm may fail. Results from both real time and simulated tracking are presented.

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

    SciTech Connect

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

    2014-03-15

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

  3. Identification of mycobacterium tuberculosis in sputum smear slide using automatic scanning microscope

    NASA Astrophysics Data System (ADS)

    Rulaningtyas, Riries; Suksmono, Andriyan B.; Mengko, Tati L. R.; Saptawati, Putri

    2015-04-01

    Sputum smear observation has an important role in tuberculosis (TB) disease diagnosis, because it needs accurate identification to avoid high errors diagnosis. In development countries, sputum smear slide observation is commonly done with conventional light microscope from Ziehl-Neelsen stained tissue and it doesn't need high cost to maintain the microscope. The clinicians do manual screening process for sputum smear slide which is time consuming and needs highly training to detect the presence of TB bacilli (mycobacterium tuberculosis) accurately, especially for negative slide and slide with less number of TB bacilli. For helping the clinicians, we propose automatic scanning microscope with automatic identification of TB bacilli. The designed system modified the field movement of light microscope with stepper motor which was controlled by microcontroller. Every sputum smear field was captured by camera. After that some image processing techniques were done for the sputum smear images. The color threshold was used for background subtraction with hue canal in HSV color space. Sobel edge detection algorithm was used for TB bacilli image segmentation. We used feature extraction based on shape for bacilli analyzing and then neural network classified TB bacilli or not. The results indicated identification of TB bacilli that we have done worked well and detected TB bacilli accurately in sputum smear slide with normal staining, but not worked well in over staining and less staining tissue slide. However, overall the designed system can help the clinicians in sputum smear observation becomes more easily.

  4. Graphene-based Hall Sensors for direct magnetic imaging by using Scanning Hall Probe Microscope

    NASA Astrophysics Data System (ADS)

    Sonusen, Selda; Aksoy, Seda; Dede, Munir; Oral, Ahmet

    2013-03-01

    Graphene has been attracting great interest due to its unique electronic and mechanical properties for both fundamental and experimental studies since 2004. Graphene is a promising material for many applications in high speed electronic and spintronic devices as well as sensors. Its high mobility makes graphene a good candidate for magnetic imaging in Scanning Hall Probe Microscope (SHPM). Hall probes are used to scan the magnetic samples to image magnetic domains in SHPM. In this work, single layer graphene produced by chemical vapor deposition technique is used to fabricate Hall sensors by optical and the e-beam lithography with sizes from 500 nm to a few micrometers. The Hall crosses are characterized by Raman mapping to make sure that they are made of a single layer graphene. The Graphene Hall Sensors noise spectra is measured as a function of different bias currents and carrier concentrations at 300 K, 77 K and 4.24K. The imaging performance of the Hall sensor will be demonstrated at different temperatures by imaging a garnet crystal using a Low Temperature Scanning Hall Probe Microscope (LT-SHPM).

  5. Demonstration of parallel scanning probe microscope for high throughput metrology and inspection

    NASA Astrophysics Data System (ADS)

    Sadeghian, Hamed; Dekker, Bert; Herfst, Rodolf; Winters, Jasper; Eigenraam, Alexander; Rijnbeek, Ramon; Nulkes, Nicole

    2015-03-01

    With the device dimensions moving towards the 1X node and below, the semiconductor industry is rapidly approaching the point where existing metrology, inspection and review tools face huge challenges in terms of resolution, the ability to resolve 3D and the throughput. Due to the advantages of sub-nanometer resolution and the ability of true 3D scanning, scanning probe microscope (SPM) and specifically atomic force microscope (AFM) are considered as alternative technologies for CD-metrology, defect inspection and review of 1X node and below. In order to meet the increasing demand for resolution and throughput of CD-metrology, defect inspection and review, TNO has previously introduced the parallel SPM concept, consisting of parallel operation of many miniaturized SPMs on a 300 and 450 mm wafer. In this paper we will present the proof of principle of the parallelization for metrology and inspection. To give an indication of the system's specifications, the throughput of scanning is 4500 sites per hour, each within an area of 1 μm2 and 1024 ×1024 pixels.

  6. Drift reduction in a scanning electrostatic force microscope for surface profile measurement

    NASA Astrophysics Data System (ADS)

    Jia, Zhigang; Ito, So; Goto, Shigeaki; Hosobuchi, Keiichiro; Shimizu, Yuki; Gao, Wei

    2014-09-01

    The influence of drifts on the measurement results of an electrostatic force microscope (EFM) based on a dual-height method for surface profile measurement is analyzed. Two types of drifts and their influence on the EFM measurement are discussed by computer simulation. It is figured out that the mechanical drift has a larger impact compared to the resonance frequency drift for the specific EFM with the conventional round-trip scan mode. It is also verified that the profile reconstruction algorithm of the dual-height method for separating the electric property distribution and the surface profile of the surface has an effect of magnifying the drift error in the result of surface profile measurement, which is a much more significant measurement of uncertainty sources for the developed EFM compared with an ordinary scanning probe microscope (SPM). A new vertical reciprocating scan (VRS) mode is then employed to reduce the influences of the drifts. The feasibility of the VRS mode is demonstrated by computer simulation and measurement experiments with a diffraction grating.

  7. Design and development of multi functional confocal laser scanning microscope with UV / VIS laser source

    NASA Astrophysics Data System (ADS)

    Kanai, Yoshikazu; Kanzaki, Yousuke; Wakaki, Moriaki; Takeyama, Norihide

    2005-08-01

    A high resolution Confocal Laser Scanning Microscope (CLSM) with UV / VIS light sources was developed as the first step of multi-functional microscope. The optical system is designed to optimize for both UV and VIS wavelengths. An UV laser is used to achieve higher resolution, and a VIS is for multi functions. A new objective lens specialized for this application was designed and fabricated. Specification of the lens and the optical system is NA:0.95, EFL:2.5mm, WD:1.5mm, Resolution:160nm and achromatic for two wavelengths of UV 325.0nm / VIS 632.8nm. Several specimens were characterized to check the performance of the system. Some optical materials under study were measured for evaluation, and interesting results could be obtained. Multi-functional measurements are being planed as a next step. This system will help the research of nano-structures, photonic-crystals and biology.

  8. A highly sensitive scanning far-infrared microscope with quantum Hall detectors

    NASA Astrophysics Data System (ADS)

    Ikushima, Kenji; Sakuma, Hisato; Komiyama, Susumu

    2003-09-01

    We develop a highly sensitive scanning far-infrared (FIR) microscope, which consists of a silicon solid immersion lens that probes FIR and a condenser lens that focuses the FIR onto a small quantum Hall detector (400 μm×400 μm). The solid immersion lens is in contact with the backside of a Hall bar sample, which is moved with a mechanical XY stage. The quantum Hall detector, which function as a narrow band FIR detector (bandwidth of about 2%), is a Hall bar with a large length-to-width ratio in integer quantum Hall effect regimes. The microscope is successfully applied to image extremely weak cyclotron emissions from quantum Hall devices with a spatial resolution of about 50 μm and a signal-to-noise ratio improved by a factor 18 compared to a previous system.

  9. Visualization of microcrack anisotropy in granite affected by afault zone, using confocal laser scanning microscope

    SciTech Connect

    Onishi, Celia T.; Shimizu, Ichiko

    2004-01-02

    Brittle deformation in granite can generate a fracture system with different patterns. Detailed fracture analyses at both macroscopic and microscopic scales, together with physical property data from a drill-core, are used to classify the effects of reverse fault deformation in four domains: (1) undeformed granite, (2) fractured granite with cataclastic seams, (3) fractured granite from the damage zone, and (4) foliated cataclasite from the core of the fault. Intact samples from two orthogonal directions, horizontal (H) and vertical (V), from the four domains indicate a developing fracture anisotropy toward the fault, which is highly developed in the damage zone. As a specific illustration of this phenomenon, resin impregnation, using a confocal laser scanning microscope (CLSM) technique is applied to visualize the fracture anisotropy developed in the Toki Granite, Japan. As a result, microcrack networks have been observed to develop in H sections and elongate open cracks in V sections, suggesting that flow pathways can be determined by deformation.

  10. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope.

    PubMed

    Ferroni, Matteo; Signoroni, Alberto; Sanzogni, Andrea; Masini, Luca; Migliori, Andrea; Ortolani, Luca; Pezza, Alessandro; Morandi, Vittorio

    2016-01-01

    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections. PMID:27646194

  11. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Ferroni, Matteo; Signoroni, Alberto; Sanzogni, Andrea; Masini, Luca; Migliori, Andrea; Ortolani, Luca; Pezza, Alessandro; Morandi, Vittorio

    2016-09-01

    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections.

  12. Imaging the p-n junction in a gallium nitride nanowire with a scanning microwave microscope

    SciTech Connect

    Imtiaz, Atif; Wallis, Thomas M.; Brubaker, Matt D.; Blanchard, Paul T.; Bertness, Kris A.; Sanford, Norman A.; Kabos, Pavel; Weber, Joel C.; Coakley, Kevin J.

    2014-06-30

    We used a broadband, atomic-force-microscope-based, scanning microwave microscope (SMM) to probe the axial dependence of the charge depletion in a p-n junction within a gallium nitride nanowire (NW). SMM enables the visualization of the p-n junction location without the need to make patterned electrical contacts to the NW. Spatially resolved measurements of S{sub 11}{sup ′}, which is the derivative of the RF reflection coefficient S{sub 11} with respect to voltage, varied strongly when probing axially along the NW and across the p-n junction. The axial variation in S{sub 11}{sup ′}  effectively mapped the asymmetric depletion arising from the doping concentrations on either side of the junction. Furthermore, variation of the probe tip voltage altered the apparent extent of features associated with the p-n junction in S{sub 11}{sup ′} images.

  13. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope

    PubMed Central

    Ferroni, Matteo; Signoroni, Alberto; Sanzogni, Andrea; Masini, Luca; Migliori, Andrea; Ortolani, Luca; Pezza, Alessandro; Morandi, Vittorio

    2016-01-01

    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections. PMID:27646194

  14. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope.

    PubMed

    Ferroni, Matteo; Signoroni, Alberto; Sanzogni, Andrea; Masini, Luca; Migliori, Andrea; Ortolani, Luca; Pezza, Alessandro; Morandi, Vittorio

    2016-09-20

    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections.

  15. Ultra low-K shrinkage behavior when under electron beam in a scanning electron microscope

    SciTech Connect

    Lorut, F.; Imbert, G.; Roggero, A.

    2013-08-28

    In this paper, we investigate the tendency of porous low-K dielectrics (also named Ultra Low-K, ULK) behavior to shrink when exposed to the electron beam of a scanning electron microscope. Various experimental electron beam conditions have been used for irradiating ULK thin films, and the resulting shrinkage has been measured through use of an atomic force microscope tool. We report the shrinkage to be a fast, cumulative, and dose dependent effect. Correlation of the shrinkage with incident electron beam energy loss has also been evidenced. The chemical modification of the ULK films within the interaction volume has been demonstrated, with a densification of the layer and a loss of carbon and hydrogen elements being observed.

  16. Scanning magneto-optical Kerr microscope with auto-balanced detection scheme.

    PubMed

    Halahovets, Y; Siffalovic, P; Jergel, M; Senderak, R; Majkova, E; Luby, S; Kostic, I; Szymanski, B; Stobiecki, F

    2011-08-01

    We have developed a scanning magneto-optical Kerr microscope dedicated to localization and measurement of the in-plane magnetization of ultra-thin layered magnetic nanostructures with high sensitivity and signal-to-noise ratio. The novel light detection scheme is based on a differential photodetector with automatic common mode noise rejection system with a high noise suppression up to 50 dB. The sensitivity of the developed detection scheme was tested by measurement of a single Co layer and a giant magnetoresistance (GMR) multilayer stack. The spatial resolution of the Kerr microscope was demonstrated by mapping an isolated 5×5 μm spin-valve pillar. PMID:21895250

  17. Scanning electron microscope and micro-CT evaluation of cranial sutures in health and disease.

    PubMed

    Anderson, Peter J; Netherway, David J; David, David J; Self, Peter

    2006-09-01

    Current knowledge of suture biology has been ascertained as a result of morphological studies of normal cranial sutures (and rarely those undergoing craniosynostosis). These were initially undertaken often using histological investigations, or more recently using CT scans, as investigative tools, but have often used animal models. However, recent technological advances have provided the potential to refine our understanding of the ultrastructure by the use of new advanced scanning technology, which offers the possibility of more detailed resolution. Our aim was to undertake detailed scans of normal, fusing and fused sutures from patients with craniosynosotosis affecting different sutures, to study the detailed structure at different stages of the fusion process using a modern micro-CT scanner and a microanalytical scanning electron microscope. We wished to include in our study all the human sutures because previous studies have mostly been undertaken using the sagittal suture. Ten sutures from seven patients have revealed a complex ultra-structural arrangement. The different patterns of bone ridging seen on the ectocranial and endocranial surfaces of the fused sagittal suture were not repeated on closer inspection of either fused coronal or lambdoid sutures. Elemental analysis confirmed that the amount of calcium increased and the amount of carbon decreased as sampled areas moved away from the suture margin. We conclude that scanning allowed detailed assessment and revealed the complex arrangement of the structure of the human cranial sutures and those undergoing the process of craniosynostosis, with some differences in final structure depending on the affected suture.

  18. Electron tomography of HEK293T cells using scanning electron microscope-based scanning transmission electron microscopy.

    PubMed

    You, Yun-Wen; Chang, Hsun-Yun; Liao, Hua-Yang; Kao, Wei-Lun; Yen, Guo-Ji; Chang, Chi-Jen; Tsai, Meng-Hung; Shyue, Jing-Jong

    2012-10-01

    Based on a scanning electron microscope operated at 30 kV with a homemade specimen holder and a multiangle solid-state detector behind the sample, low-kV scanning transmission electron microscopy (STEM) is presented with subsequent electron tomography for three-dimensional (3D) volume structure. Because of the low acceleration voltage, the stronger electron-atom scattering leads to a stronger contrast in the resulting image than standard TEM, especially for light elements. Furthermore, the low-kV STEM yields less radiation damage to the specimen, hence the structure can be preserved. In this work, two-dimensional STEM images of a 1-μm-thick cell section with projection angles between ±50° were collected, and the 3D volume structure was reconstructed using the simultaneous iterative reconstructive technique algorithm with the TomoJ plugin for ImageJ, which are both public domain software. Furthermore, the cross-sectional structure was obtained with the Volume Viewer plugin in ImageJ. Although the tilting angle is constrained and limits the resulting structural resolution, slicing the reconstructed volume generated the depth profile of the thick specimen with sufficient resolution to examine cellular uptake of Au nanoparticles, and the final position of these nanoparticles inside the cell was imaged.

  19. Manipulation of nanoparticles of different shapes inside a scanning electron microscope

    PubMed Central

    Polyakov, Boris; Dorogin, Leonid M; Butikova, Jelena; Antsov, Mikk; Oras, Sven; Lõhmus, Rünno; Kink, Ilmar

    2014-01-01

    Summary In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry. Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed. PMID:24605279

  20. Scanning microscopic evaluation of canal débridement as compared to present methods.

    PubMed

    Dupont, A A; Brady, J M; del Rio, C E

    1977-07-01

    Ninety-one samples of root canal contents were obtained from thirty-one teeth. The paper point samples were evaluated for exudate, subjected to bacteriologic analysis, and/or examined with the scanning electron microscope. A comparison was made between the presence or absence of exudate, positive and negative cultures, and the presence or absence of contaminants as examined under the SEM. All three methods of evaluation showed some degree of correlationmscanning electron microscopy appears to be a more sensitive test for canal status.

  1. Magnetic detection of cracks by fatigue in mild steels using a scanning Hall-sensor microscope

    NASA Astrophysics Data System (ADS)

    Oota, A.; Ito, T.; Kawano, K.; Sugiyama, D.; Aoki, H.

    1999-01-01

    We fabricated a scanning Hall-sensor microscope with an active area 50 μm×50 μm that can be served as a simple and conventional tool for nondestructive evaluation of magnetic materials. Using this, we succeeded in magnetic detection of small cracks (˜10 mm long and ˜0.1 mm wide) in mild steels with a yield point of 29 kgf/mm2, caused by a plane-bending fatigue test at a stress amplitude of 28 kgf/mm2 and a frequency of 29.2 Hz.

  2. Electron channeling contrast imaging studies of nonpolar nitrides using a scanning electron microscope

    SciTech Connect

    Naresh-Kumar, G.; Kraeusel, S.; Bruckbauer, J.; Edwards, P. R.; Hourahine, B.; Trager-Cowan, C.; Mauder, C.; Heuken, M.; Wang, K. R.; Trampert, A.; Kalisch, H.; Vescan, A.; Giesen, C.; Day, A. P.

    2013-04-08

    Threading dislocations, stacking faults, and associated partial dislocations significantly degrade the optical and electrical properties of materials such as non-polar III-nitride semiconductor thin films. Stacking faults are generally difficult to detect and quantify with existing characterization techniques. We demonstrate the use of electron channeling contrast imaging in the scanning electron microscope to non-destructively reveal basal plane stacking faults terminated by partial dislocations in m-plane GaN and InGaN/GaN multiple quantum well structures grown on {gamma}-LiAlO{sub 2} by metal organic vapor phase epitaxy.

  3. Scanning electron microscopic observation of the architecture of collagen fibres in chicken M. iliotibialis lateralis.

    PubMed

    Iwamoto, H; Tabata, S; Kakakibara, K; Nishimura, S; Gotoh, T; Koga, Y

    2001-07-01

    1. The collagen architecture of M. iliotibialis lateralis in chicken was observed under the scanning electron microscope after muscle maceration in NaOH. 2. Immunohistochemical methods showed Type I and III collagens to be distributed over both perimysium and endomysium. 3. Thick perimysium around secondary myofibre fasciculi was composed of many large longitudinal collagen bundles and a few small circumferential bundles. In contrast, thin perimysium around primary myofibre fasciculi showed mainly circumferential bundles. 4. Endomysium had a honeycomb-like structure and consisted of a fine collagen mesh, its main fibre striation being circumferential. 5. It is suggested that functional demand differs between thick perimysium and thin endomysium.

  4. Chemically sensitive structure-imaging with a scanning transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Pennycook, S. J.; Boatner, L. A.

    1988-12-01

    Problems associated with the phase-contrast method of conventional high-resolution electron microscopy may be avoided, and high atomic-number contrast in the sample obtained, by using a high-angle detector in a scanning transmission electron microscope. Results of this technique applied to single crystals of the high-transition temperature superconductors YBa2Cu3O(7-x) and ErBa2Cu3O(7-x) are presented. The heavy-atom planes are directly imaged as bright lines, and the probable structure of an observed defect is directly inferred from its image.

  5. Resonance oscillation damping of a scanning microscope probe by a near-surface viscous liquid layer

    NASA Astrophysics Data System (ADS)

    Maslenikov, I. I.; Reshetov, N. V.

    2016-05-01

    Viscous liquid layer motion between a probe with a tip shaped as a paraboloid of revolution and a surface is considered for semicontact-mode operation of a scanning probe microscope. The presence of a viscous liquid layer leads to energy dissipation and is one of the factors responsible for the decrease in the probe oscillation amplitude. The Reynolds equation for viscous liquid motion is used to obtain an analytic solution to the problem. The formula derived for the loss is compared with experimental data obtained for probes and layers with various curvature radii and viscosities.

  6. TRIASSIC: the Time-Resolved Industrial Alpha-Source Scanning Induced Current microscope

    NASA Astrophysics Data System (ADS)

    Pallone, Arthur

    Time-resolved ion beam induced current (TRIBIC) microscopy yields useful information such as carrier mobility and lifetimes in semiconductors and defect locations in devices; however, traditional TRIBIC uses large, expensive particle accelerators that require specialized training to operate and maintain. The time-resolved industrial alpha-source scanning induced current (TRIASSIC) microscope transforms TRIBIC by replacing the particle accelerator facility with an affordable, tabletop instrument suitable for use in research and education at smaller colleges and universities. I will discuss the development of, successes with, setbacks to and future directions for TRIASSIC.

  7. The Scanning Electron Microscope As An Accelerator For The Undergraduate Advanced Physics Laboratory

    SciTech Connect

    Peterson, Randolph S.; Berggren, Karl K.; Mondol, Mark

    2011-06-01

    Few universities or colleges have an accelerator for use with advanced physics laboratories, but many of these institutions have a scanning electron microscope (SEM) on site, often in the biology department. As an accelerator for the undergraduate, advanced physics laboratory, the SEM is an excellent substitute for an ion accelerator. Although there are no nuclear physics experiments that can be performed with a typical 30 kV SEM, there is an opportunity for experimental work on accelerator physics, atomic physics, electron-solid interactions, and the basics of modern e-beam lithography.

  8. Light and scanning electron microscopic investigations on MiteStop-treated poultry red mites.

    PubMed

    Locher, Nina; Klimpel, Sven; Abdel-Ghaffar, Fathy; Al Rasheid, Khaled A S; Mehlhorn, Heinz

    2010-07-01

    Recent studies of the neem seed product MiteStop showed that it has a good acaricidal effect against all developmental stages of the poultry red mite, Dermanyssus gallinae. In vitro tests proved an efficacy at direct contact, as well as by fumigant toxicity. Light and scanning electron microscopic (SEM) investigations showed no clear, morphologically visible signs of an effect caused by fumigant toxicity. Direct contact with the neem product, however, seemed to be of great impact. Chicken mites turned dark brown or even black after being treated with the neem product. SEM analysis showed damages along the body surface of the mites. PMID:20563823

  9. SEM analysis of ionizing radiation effects in linear integrated circuits. [Scanning Electron Microscope

    NASA Technical Reports Server (NTRS)

    Stanley, A. G.; Gauthier, M. K.

    1977-01-01

    A successful diagnostic technique was developed using a scanning electron microscope (SEM) as a precision tool to determine ionization effects in integrated circuits. Previous SEM methods radiated the entire semiconductor chip or major areas. The large area exposure methods do not reveal the exact components which are sensitive to radiation. To locate these sensitive components a new method was developed, which consisted in successively irradiating selected components on the device chip with equal doses of electrons /10 to the 6th rad (Si)/, while the whole device was subjected to representative bias conditions. A suitable device parameter was measured in situ after each successive irradiation with the beam off.

  10. Scanning-electron-microscope study of normal-impingement erosion of ductile metals

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Salik, J.

    1980-01-01

    Scanning electron microscopy was used to characterize the erosion of annealed copper and aluminum surfaces produced by both single- and multiple-particle impacts. Macroscopic 3.2 mm diameter steel balls and microscopic, brittle erodant particles were projected by a gas gun system so as to impact at normal incidence at speeds up to 140 m/sec. During the impacts by the brittle erodant particles, at lower speeds the erosion behavior was similar to that observed for the larger steel balls. At higher velocities, particle fragmentation and the subsequent cutting by the radial wash of debris created a marked change in the erosion mechanism.

  11. The organization of collagen in cryofractured rabbit articular cartilage: a scanning electron microscopic study.

    PubMed

    Clark, J M

    1985-01-01

    Adult rabbit articular cartilage was prepared for scanning electron microscopy using, in order, glutaraldehyde fixation, enzymatic removal of proteoglycan, dehydration in ethanol, cryofracture in liquid nitrogen, and critical-point drying. Enzymes were effective in fixed material. Fixation, cryofracture, alignment of fracture surfaces with "split lines," and retention of subchondral bone were found to be necessary steps for the preservation of collagen detail. The fibrous framework was found to be similar to that proposed by Benninghoff and favored by more recent phase-contrast microscopic studies. Vertical fibers extending from subchondral bone and a network of tangentially oriented superficial fibrils converge in the transitional zone. No random layer is seen. Pericellular capsules interdigitate with the vertical fibers. When cartilage is prepared in a manner that minimizes tissue damage, scanning electron microscopy provides useful, unique information. PMID:3981292

  12. High-speed imaging upgrade for a standard sample scanning atomic force microscope using small cantilevers

    SciTech Connect

    Adams, Jonathan D.; Nievergelt, Adrian; Erickson, Blake W.; Yang, Chen; Dukic, Maja; Fantner, Georg E.

    2014-09-15

    We present an atomic force microscope (AFM) head for optical beam deflection on small cantilevers. Our AFM head is designed to be small in size, easily integrated into a commercial AFM system, and has a modular architecture facilitating exchange of the optical and electronic assemblies. We present two different designs for both the optical beam deflection and the electronic readout systems, and evaluate their performance. Using small cantilevers with our AFM head on an otherwise unmodified commercial AFM system, we are able to take tapping mode images approximately 5–10 times faster compared to the same AFM system using large cantilevers. By using additional scanner turnaround resonance compensation and a controller designed for high-speed AFM imaging, we show tapping mode imaging of lipid bilayers at line scan rates of 100–500 Hz for scan areas of several micrometers in size.

  13. Image accumulation, storage, and display system for a scanning transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Zubin, J. A.; Wiggins, J. W.

    1980-01-01

    This paper describes a high resolution scanning transmission electron microscope data collection, storage, and display system. Included are a novel analog-to-digital converter, a digital hardware divider, a direct memory access interface to a PDP 11/20, a flicker-free gray scale TV display, two new gray scale hardcopy devices, and a software description of the system. The system described here accepts three 8-bit channels of image data from a single picture element every 30 μs. Each picture element intensity is measured simultaneously by three detectors. Scans of 64, 128, 256, or 512 lines of picture elements are provided. All the data are stored on one of eight disk files, and one of the three simultaneous data channels is displayed on a digitally refreshed TV screen in real time. Production of hard-copy images and magnetic tape images, and other manipulations of the data are provided after data accumulation is terminated.

  14. Building a 3d Reference Model for Canal Tunnel Surveying Using Sonar and Laser Scanning

    NASA Astrophysics Data System (ADS)

    Moisan, E.; Charbonnier, P.; Foucher, P.; Grussenmeyer, P.; Guillemin, S.; Koehl, M.

    2015-04-01

    Maintaining canal tunnels is not only a matter of cultural and historical preservation, but also a commercial necessity and a security issue. This contribution adresses the problem of building a full 3D reference model of a canal tunnel by merging SONAR (for underwater data recording) and LASER data (for the above-water parts). Although both scanning devices produce point clouds, their properties are rather different. In particular, SONAR data are very noisy and their processing raises several issues related to the device capacities, the acquisition setup and the tubular shape of the tunnel. The proposed methodology relies on a denoising step by meshing, followed by the registration of SONAR data with the geo-referenced LASER data. Since there is no overlap between point clouds, a 3-step procedure is proposed to robustly estimate the registration parameters. In this paper, we report a first experimental survey, which concerned the entrance of a canal tunnel. The obtained results are promising and the analysis of the method raises several improvement directions that will help obtaining more accurate models, in a more automated fashion, in the limits of the involved technology.

  15. Origin of Symmetric Dimer Images of Si(001) Observed by Low-Temperature Scanning Tunneling Microscopy

    PubMed Central

    Ren, Xiao-Yan; Kim, Hyun-Jung; Niu, Chun-Yao; Jia, Yu; Cho, Jun-Hyung

    2016-01-01

    It has been a long-standing puzzle why buckled dimers of the Si(001) surface appeared symmetric below ~20 K in scanning tunneling microscopy (STM) experiments. Although such symmetric dimer images were concluded to be due to an artifact induced by STM measurements, its underlying mechanism is still veiled. Here, we demonstrate, based on a first-principles density-functional theory calculation, that the symmetric dimer images are originated from the flip-flop motion of buckled dimers, driven by quantum tunneling (QT). It is revealed that at low temperature the tunneling-induced surface charging with holes reduces the energy barrier for the flipping of buckled dimers, thereby giving rise to a sizable QT-driven frequency of the flip-flop motion. However, such a QT phenomenon becomes marginal in the tunneling-induced surface charging with electrons. Our findings provide an explanation for low-temperature STM data that exhibits apparent symmetric (buckled) dimer structure in the filled-state (empty-state) images. PMID:27292000

  16. Origin of Symmetric Dimer Images of Si(001) Observed by Low-Temperature Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Ren, Xiao-Yan; Kim, Hyun-Jung; Niu, Chun-Yao; Jia, Yu; Cho, Jun-Hyung

    2016-06-01

    It has been a long-standing puzzle why buckled dimers of the Si(001) surface appeared symmetric below ~20 K in scanning tunneling microscopy (STM) experiments. Although such symmetric dimer images were concluded to be due to an artifact induced by STM measurements, its underlying mechanism is still veiled. Here, we demonstrate, based on a first-principles density-functional theory calculation, that the symmetric dimer images are originated from the flip-flop motion of buckled dimers, driven by quantum tunneling (QT). It is revealed that at low temperature the tunneling-induced surface charging with holes reduces the energy barrier for the flipping of buckled dimers, thereby giving rise to a sizable QT-driven frequency of the flip-flop motion. However, such a QT phenomenon becomes marginal in the tunneling-induced surface charging with electrons. Our findings provide an explanation for low-temperature STM data that exhibits apparent symmetric (buckled) dimer structure in the filled-state (empty-state) images.

  17. Origin of Symmetric Dimer Images of Si(001) Observed by Low-Temperature Scanning Tunneling Microscopy.

    PubMed

    Ren, Xiao-Yan; Kim, Hyun-Jung; Niu, Chun-Yao; Jia, Yu; Cho, Jun-Hyung

    2016-06-13

    It has been a long-standing puzzle why buckled dimers of the Si(001) surface appeared symmetric below ~20 K in scanning tunneling microscopy (STM) experiments. Although such symmetric dimer images were concluded to be due to an artifact induced by STM measurements, its underlying mechanism is still veiled. Here, we demonstrate, based on a first-principles density-functional theory calculation, that the symmetric dimer images are originated from the flip-flop motion of buckled dimers, driven by quantum tunneling (QT). It is revealed that at low temperature the tunneling-induced surface charging with holes reduces the energy barrier for the flipping of buckled dimers, thereby giving rise to a sizable QT-driven frequency of the flip-flop motion. However, such a QT phenomenon becomes marginal in the tunneling-induced surface charging with electrons. Our findings provide an explanation for low-temperature STM data that exhibits apparent symmetric (buckled) dimer structure in the filled-state (empty-state) images.

  18. Origin of Symmetric Dimer Images of Si(001) Observed by Low-Temperature Scanning Tunneling Microscopy.

    PubMed

    Ren, Xiao-Yan; Kim, Hyun-Jung; Niu, Chun-Yao; Jia, Yu; Cho, Jun-Hyung

    2016-01-01

    It has been a long-standing puzzle why buckled dimers of the Si(001) surface appeared symmetric below ~20 K in scanning tunneling microscopy (STM) experiments. Although such symmetric dimer images were concluded to be due to an artifact induced by STM measurements, its underlying mechanism is still veiled. Here, we demonstrate, based on a first-principles density-functional theory calculation, that the symmetric dimer images are originated from the flip-flop motion of buckled dimers, driven by quantum tunneling (QT). It is revealed that at low temperature the tunneling-induced surface charging with holes reduces the energy barrier for the flipping of buckled dimers, thereby giving rise to a sizable QT-driven frequency of the flip-flop motion. However, such a QT phenomenon becomes marginal in the tunneling-induced surface charging with electrons. Our findings provide an explanation for low-temperature STM data that exhibits apparent symmetric (buckled) dimer structure in the filled-state (empty-state) images. PMID:27292000

  19. Influence of atomic tip structure on the intensity of inelastic tunneling spectroscopy data analyzed by combined scanning tunneling spectroscopy, force microscopy, and density functional theory

    NASA Astrophysics Data System (ADS)

    Okabayashi, Norio; Gustafsson, Alexander; Peronio, Angelo; Paulsson, Magnus; Arai, Toyoko; Giessibl, Franz J.

    2016-04-01

    Achieving a high intensity in inelastic scanning tunneling spectroscopy (IETS) is important for precise measurements. The intensity of the IETS signal can vary by up to a factor of 3 for various tips without an apparent reason accessible by scanning tunneling microscopy (STM) alone. Here, we show that combining STM and IETS with atomic force microscopy enables carbon monoxide front-atom identification, revealing that high IETS intensities for CO/Cu(111) are obtained for single-atom tips, while the intensity drops sharply for multiatom tips. Adsorption of the CO molecule on a Cu adatom [CO/Cu/Cu(111)] such that the molecule is elevated over the substrate strongly diminishes the tip dependence of IETS intensity, showing that an elevated position channels most of the tunneling current through the CO molecule even for multiatom tips, while a large fraction of the tunneling current bypasses the CO molecule in the case of CO/Cu(111).

  20. Scanning tunneling microscopy study of organic molecules and self-assembled monolayers

    NASA Astrophysics Data System (ADS)

    Park, Hayn

    In this dissertation I present my findings on alkanethiol self-assembled monolayers (SAM) on Au(111), as well as investigations of the self-assembly and electron transport properties of a custom-synthesized organic molecule (bis-phenyloxazole: BPO) chosen for its interesting physical and electronic structure. Utilizing scanning tunneling microscopy (STM) techniques, we observed unique molecular structures at the boundaries of single-species alkanethiol SAM domains, and propose packing arrangements for the observed structures. We also found evidence for island formation in alkanethiol SAMs; these islands were dynamic and exhibited ordered packing of the adsorbed molecules. For codeposited two-species (dodecanethiol, octanethiol) SAMs, we observed preferential insertion of the longer molecules at domain boundaries, edges, and defect sites, and found that they tended to segregate into separate domains. Scanning tunneling spectroscopy (STS) of the inserted dodecanethiol molecules revealed evidence of conduction resonances within the HOMO-LUMO gap. We explored the charge transport and self-assembly properties of the BPO molecules on a Au(111) surface. The molecules self-assembled into a novel columnar structure after annealing in vacuum. We compare tunneling spectroscopy results to ab initio computations of the molecular orbitals.

  1. Direct visualization of the N impurity state in dilute GaNAs using scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Ishida, Nobuyuki; Jo, Masafumi; Mano, Takaaki; Sakuma, Yoshiki; Noda, Takeshi; Fujita, Daisuke

    2015-10-01

    The interaction between nitrogen (N) impurity states in III-V compounds plays a key role in controlling optoelectronic properties of the host materials. Here, we use scanning tunneling microscopy to characterize the spatial distribution and electronic properties of N impurity states in dilute GaNAs. We demonstrated that the N impurity states can be directly visualized by taking empty state current images using the multipass scanning method. The N impurity states broadened over several nanometers and exhibited a highly anisotropic distribution with a bowtie-like shape on the GaAs(110) surface, which can be explained by anisotropic propagation of strain along the zigzag chains of Ga and As atoms in the {110} plane. Our experimental findings provide strong insights into a possible role of N impurity states in modifying properties of the host materials.The interaction between nitrogen (N) impurity states in III-V compounds plays a key role in controlling optoelectronic properties of the host materials. Here, we use scanning tunneling microscopy to characterize the spatial distribution and electronic properties of N impurity states in dilute GaNAs. We demonstrated that the N impurity states can be directly visualized by taking empty state current images using the multipass scanning method. The N impurity states broadened over several nanometers and exhibited a highly anisotropic distribution with a bowtie-like shape on the GaAs(110) surface, which can be explained by anisotropic propagation of strain along the zigzag chains of Ga and As atoms in the {110} plane. Our experimental findings provide strong insights into a possible role of N impurity states in modifying properties of the host materials. Electronic supplementary information (ESI) available: Identification of N impurity positions in terms of depth of depressions in the filled state topographic image. Filled state topographic images of N impurity in the fourth plane. Slight modification of topographic height

  2. Novel control scheme for a high-speed metrological scanning probe microscope

    NASA Astrophysics Data System (ADS)

    Vorbringer-Dorozhovets, N.; Hausotte, T.; Manske, E.; Shen, J. C.; Jäger, G.

    2011-09-01

    Some time ago, an interferometer-based metrological scanning probe microscope (SPM) was developed at the Institute of Process Measurement and Sensor Technology of the Ilmenau University of Technology, Germany. The specialty of this SPM is the combined deflection detection system that comprises an interferometer and a beam deflection. Due to this system it is possible to simultaneously measure the displacement, bending and torsion of the probe (cantilever). The SPM is integrated into a nanopositioning and nanomeasuring machine (NPM machine) and allows measurements with a resolution of 0.1 nm over a range of 25 mm × 25 mm × 5 mm. Excellent results were achieved for measurements of calibrated step height and lateral standards and these results are comparable to the calibration values from the Physikalisch-Technische Bundesanstalt (PTB) (Dorozhovets N et al 2007 Proc. SPIE 6616 661624-1-7). The disadvantage was a low attainable scanning speed and accordingly large expenditure of time. Control dynamics and scanning speed are limited because of the high masses of the stage and corner mirror of the machine. For the vertical axis an additional high-speed piezoelectric drive is integrated in the SPM in order to increase the measuring dynamics. The movement of the piezoelectric drive is controlled and traceable measured by the interferometer. Hence, nonlinearity and hysteresis in the actuator do not affect the measurement. The outcome of this is an improvement of the bending control of the cantilever and much higher scan speeds of up to 200 µm s-1.

  3. Atmospheric scanning electron microscope system with an open sample chamber: configuration and applications.

    PubMed

    Nishiyama, Hidetoshi; Koizumi, Mitsuru; Ogawa, Koji; Kitamura, Shinich; Konyuba, Yuji; Watanabe, Yoshiyuki; Ohbayashi, Norihiko; Fukuda, Mitsunori; Suga, Mitsuo; Sato, Chikara

    2014-12-01

    An atmospheric scanning electron microscope (ASEM) with an open sample chamber and optical microscope (OM) is described and recent developments are reported. In this ClairScope system, the base of the open sample dish is sealed to the top of the inverted SEM column, allowing the liquid-immersed sample to be observed by OM from above and by SEM from below. The optical axes of the two microscopes are aligned, ensuring that the same sample areas are imaged to realize quasi-simultaneous correlative microscopy in solution. For example, the cathodoluminescence of ZnO particles was directly demonstrated. The improved system has (i) a fully motorized sample stage, (ii) a column protection system in the case of accidental window breakage, and (iii) an OM/SEM operation system controlled by a graphical user interface. The open sample chamber allows the external administration of reagents during sample observation. We monitored the influence of added NaCl on the random motion of silica particles in liquid. Further, using fluorescence as a transfection marker, the effect of small interfering RNA-mediated knockdown of endogenous Varp on Tyrp1 trafficking in melanocytes was examined. A temperature-regulated titanium ASEM dish allowed the dynamic observation of colloidal silver nanoparticles as they were heated to 240°C and sintered. PMID:25062041

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

    PubMed

    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

  5. Scanning thermal probe microscope method for the determination of thermal diffusivity of nanocomposite thin films.

    PubMed

    Varandani, Deepak; Agarwal, Khushboo; Brugger, Juergen; Mehta, Bodh Raj

    2016-08-01

    A commercial scanning thermal microscope has been upgraded to facilitate its use in estimating the radial thermal diffusivity of thin films close to room temperature. The modified setup includes a microcontroller driven microhotplate coupled with a Bluetooth module for wireless control. The microcontroller board (Arduino Leonardo) is used to generate a bias of suitable voltage amplitude and pulse duration which is applied across the microhotplate contact pads. A corresponding heat pulse from the Pt heating element (1 mm(2)) embedded within the microhotplate is delivered to the lower surface of the thin film (25 mm(2)) deposited over it. The large difference in the dimensions of the heating source and the thin film surface causes heat to flow radially outwards on the top surface of the latter. The decay of this radial heat wave as it flows outwards is recorded by the scanning thermal microscope in terms of temperature-time (T-t) profiles at varying positions around the central heating zone. A fitting procedure is suggested to extract the thermal diffusivity value from the array of T-t profiles. The efficacy of the above setup has been established by evaluating the thermal diffusivities of Bi2Te3 and Bi2Te3:Si thin film samples. Further, with only minor alterations in design the capabilities of the above setup can be extended to estimate the axial thermal diffusivity and specific heat of thin films, as a function of temperature. PMID:27587146

  6. Scanning thermal probe microscope method for the determination of thermal diffusivity of nanocomposite thin films.

    PubMed

    Varandani, Deepak; Agarwal, Khushboo; Brugger, Juergen; Mehta, Bodh Raj

    2016-08-01

    A commercial scanning thermal microscope has been upgraded to facilitate its use in estimating the radial thermal diffusivity of thin films close to room temperature. The modified setup includes a microcontroller driven microhotplate coupled with a Bluetooth module for wireless control. The microcontroller board (Arduino Leonardo) is used to generate a bias of suitable voltage amplitude and pulse duration which is applied across the microhotplate contact pads. A corresponding heat pulse from the Pt heating element (1 mm(2)) embedded within the microhotplate is delivered to the lower surface of the thin film (25 mm(2)) deposited over it. The large difference in the dimensions of the heating source and the thin film surface causes heat to flow radially outwards on the top surface of the latter. The decay of this radial heat wave as it flows outwards is recorded by the scanning thermal microscope in terms of temperature-time (T-t) profiles at varying positions around the central heating zone. A fitting procedure is suggested to extract the thermal diffusivity value from the array of T-t profiles. The efficacy of the above setup has been established by evaluating the thermal diffusivities of Bi2Te3 and Bi2Te3:Si thin film samples. Further, with only minor alterations in design the capabilities of the above setup can be extended to estimate the axial thermal diffusivity and specific heat of thin films, as a function of temperature.

  7. Excitation-scanning hyperspectral imaging system for microscopic and endoscopic applications

    NASA Astrophysics Data System (ADS)

    Mayes, Sam A.; Leavesley, Silas J.; Rich, Thomas C.

    2016-04-01

    Current microscopic and endoscopic technologies for cancer screening utilize white-light illumination sources. Hyper-spectral imaging has been shown to improve sensitivity while retaining specificity when compared to white-light imaging in both microscopy and in vivo imaging. However, hyperspectral imaging methods have historically suffered from slow acquisition times due to the narrow bandwidth of spectral filters. Often minutes are required to gather a full image stack. We have developed a novel approach called excitation-scanning hyperspectral imaging that provides 2-3 orders of magnitude increased signal strength. This reduces acquisition times significantly, allowing for live video acquisition. Here, we describe a preliminary prototype excitation-scanning hyperspectral imaging system that can be coupled with endoscopes or microscopes for hyperspectral imaging of tissues and cells. Our system is comprised of three subsystems: illumination, transmission, and imaging. The illumination subsystem employs light-emitting diode arrays to illuminate at different wavelengths. The transmission subsystem utilizes a unique geometry of optics and a liquid light guide. Software controls allow us to interface with and control the subsystems and components. Digital and analog signals are used to coordinate wavelength intensity, cycling and camera triggering. Testing of the system shows it can cycle 16 wavelengths at as fast as 1 ms per cycle. Additionally, more than 18% of the light transmits through the system. Our setup should allow for hyperspectral imaging of tissue and cells in real time.

  8. Scanning thermal probe microscope method for the determination of thermal diffusivity of nanocomposite thin films

    NASA Astrophysics Data System (ADS)

    Varandani, Deepak; Agarwal, Khushboo; Brugger, Juergen; Mehta, Bodh Raj

    2016-08-01

    A commercial scanning thermal microscope has been upgraded to facilitate its use in estimating the radial thermal diffusivity of thin films close to room temperature. The modified setup includes a microcontroller driven microhotplate coupled with a Bluetooth module for wireless control. The microcontroller board (Arduino Leonardo) is used to generate a bias of suitable voltage amplitude and pulse duration which is applied across the microhotplate contact pads. A corresponding heat pulse from the Pt heating element (1 mm2) embedded within the microhotplate is delivered to the lower surface of the thin film (25 mm2) deposited over it. The large difference in the dimensions of the heating source and the thin film surface causes heat to flow radially outwards on the top surface of the latter. The decay of this radial heat wave as it flows outwards is recorded by the scanning thermal microscope in terms of temperature-time (T-t) profiles at varying positions around the central heating zone. A fitting procedure is suggested to extract the thermal diffusivity value from the array of T-t profiles. The efficacy of the above setup has been established by evaluating the thermal diffusivities of Bi2Te3 and Bi2Te3:Si thin film samples. Further, with only minor alterations in design the capabilities of the above setup can be extended to estimate the axial thermal diffusivity and specific heat of thin films, as a function of temperature.

  9. An universal and accurate replica technique for scanning electron microscope study in clinical dentistry.

    PubMed

    Lambrechts, P; Vanherle, G; Davidson, C

    1981-09-01

    One of the main concerns of dental research is the observation of the oral tissues and the materials applied to the dentition. The changes in composition and structure of the outer surfaces and the materials deposited on these surfaces are of special interest. In the literature, a variety of replica techniques for these purposes is described (Grundy in 1971 [12]; Saxton in 1973 [25]). The use of these techniques is limited because of artifacts in the samples, and a restricted resolution power resulting from useful magnifications in the order of 800x. An accurate and universal replica technique for the examination of specimens to be viewed under the SEM has been developed. The first impression is made by a light body silicone elastomer (President Coltene). The positive replica is made by electrodeposition of copper in an electro plating bath (Acru plat 5 electronic, Dr. Th. Wieland, D-7530 Pforzheim). The reliability and accuracy of this replica technique was verified by a scanning electron microscopic comparison of the replicas and the actual structures of etched enamel. To illustrate the applicability of the replica technique to structures with much lower hardness, also high resolution images of dental plaque were produced. The copper surface offers a perfect, original and proper electroconductive medium that withstands the bombardment of electrons and the relatively severe conditions in the scanning electron microscope. Reproducibility was accurate as judged by the duplication in position, size, and shape of the fine detail at magnifications of 7500x offering a resolution of 25 nm.

  10. Measuring calcium levels in Saprolegnia ferax using the two-photon laser scanning microscope

    NASA Astrophysics Data System (ADS)

    Lilje, Osu

    2003-07-01

    xThe genus Saprolegnia in the phylum Oomycetes contains a number of parasitic species that can cause a range of important animal diseases. The aim of this study was to measure the calcium gradient, one of the growth regulating mechanisms, in Saprolegnia ferax. The two-photon laser scanning microscope allowed for detailed physiological measurements of calcium levels along the fungus-like hyphae of S.ferax. Calcium concentration was determined by making ratiometric calculation of emission levels of the calcium-sensitive fluorochrome Indo-1 at 485nm to 405nm. The calculated values were compared to the intracellular calibration values. The advantage of the two-photon laser scanning microscope is that it allows minor changes in concentration to be detected in highly localized regions of the hyphae. The technique used in this study minimized background and autofluorescence and therefore allowed for more accurate changes in intracellular Ca2+ concentration to be detected. The calcium concentration at the hyphal tip and 5, 10 and 40μm distal to the tip were calculated to be 65, 17, 38 and 20nM respectively, confirming other studies that suggest a tip-high calcium gradient.

  11. Separation of image-distortion sources and magnetic-field measurement in scanning electron microscope (SEM).

    PubMed

    Płuska, Mariusz; Czerwinski, Andrzej; Ratajczak, Jacek; Katcki, Jerzy; Oskwarek, Lukasz; Rak, Remigiusz

    2009-01-01

    The electron-microscope image distortion generated by electromagnetic interference (EMI) is an important problem for accurate imaging in scanning electron microscopy (SEM). Available commercial solutions to this problem utilize sophisticated hardware for EMI detection and compensation. Their efficiency depends on the complexity of distortions influence on SEM system. Selection of a proper method for reduction of the distortions is crucial. The current investigations allowed for a separation of the distortions impact on several components of SEM system. A sum of signals from distortion sources causes wavy deformations of specimen shapes in SEM images. The separation of various reasons of the distortion is based on measurements of the periodic deformations of the images for different electron beam energies and working distances between the microscope final aperture and the specimen. Using the SEM images, a direct influence of alternating magnetic field on the electron beam was distinguished. Distortions of electric signals in the scanning block of SEM were also separated. The presented method separates the direct magnetic field influence on the electron beam below the SEM final aperture (in the chamber) from its influence above this aperture (in the electron column). It also allows for the measurement of magnetic field present inside the SEM chamber. The current investigations gave practical guidelines for selecting the most efficient solution for reduction of the distortions.

  12. A scanning photoelectron microscope (SPEM) at the National Synchrotron Light Source (NSLS)

    SciTech Connect

    Ade, H.; Kirz, J.; Hulbert, S.; Johnson, E.; Anderson, E.; Kern, D. . Dept. of Physics; Brookhaven National Lab., Upton, NY; Lawrence Berkeley Lab., CA; International Business Machines Corp., Yorktown Heights, NY . Thomas J. Watson Research Center)

    1989-01-01

    We are in the process of developing and commissioning a scanning photoelectron microscope (SPEM) at the X1A beamline of the National Synchrotron Light Source (NSLS). It is designed to make use of the Soft X-ray Undulator (SXU) at the NSLS. This high brightness source illuminates a Fresnel zone plate, which forms a focused probe, {<=} 0.2{mu}m in size, on the specimen surface. A grating monochromator selects the photon energy in the 400-800 eV range with an energy resolution of better than 1 eV. The expected flux in the focus is in the 5 {times} 10{sup 7} {minus} 10{sup 9} photons/s range. A single pass Cylindrical Mirror Analyzer (CMA) is used to record photoemission spectra, or to form an image within a fixed electron energy bandwidth as the specimen is mechanically scanned. As a first test, a 1000 mesh Au grid was successfully imaged with a resolution of about 1{mu}m and the CMA tuned to the Au 4 f photoelectron peak. Once it is commissioned, a program is planned which will utilize the microscope to study beam sensitive systems, such as thin oxide/sub-oxide films of alumina and silica, and ultimately various adsorbates on these films. 14 refs., 4 figs.

  13. Measurement of shear strength for HOPG with scanning tunneling microscopy by thermal excitation method.

    PubMed

    Ding, X D; Wang, Y Z; Xiong, X M; Du, X S; Zhang, J X

    2012-04-01

    An experimental observation of force interactions in scanning tunneling microscopy (STM) is presented. A technique for measuring force interactions between a conventional STM probe and a sample by spectra analysis of its thermal fluctuations from tunneling current in STM is developed theoretically and experimentally. Thermally excited fluctuation of the STM probe is exactly discerned in air and then force gradient is determined from its corresponding eigen-frequency with a formula similar to that for a small-amplitude atomic force microscopy (AFM). The observed force interactions are consistent with forces in dynamic AFM. Shear strength of 7 GPa for highly oriented pyrolytic graphite (HOPG) under compressive stress is obtained from the experiment and using the elastic theory. We believe that this technique is of scientific significance as it enables accurate measurement of short-range force interactions at atomic scale under true STM conditions.

  14. Molecular electronics of a single photosystem I reaction center: studies with scanning tunneling microscopy and spectroscopy.

    PubMed Central

    Lee, I; Lee, J W; Warmack, R J; Allison, D P; Greenbaum, E

    1995-01-01

    Thylakoids and photosystem I (PSI) reaction centers were imaged by scanning tunneling microscopy. The thylakoids were isolated from spinach chloroplasts, and PSI reaction centers were extracted from thylakoid membranes. Because thylakoids are relatively thick nonconductors, they were sputter-coated with Pd/Au before imaging. PSI photosynthetic centers and chemically platinized PSI were investigated without sputter-coating. They were mounted on flat gold substrates that had been treated with mercaptoacetic acid to help bind the proteins. With tunneling spectroscopy, the PSI centers displayed a semiconductor-like response with a band gap of 1.8 eV. Lightly platinized (platinized for 1 hr) centers displayed diode-like conduction that resulted in dramatic contrast changes between images taken with opposite bias voltages. The electronic properties of this system were stable under long-term storage. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:11607515

  15. Atomic-scale electrochemistry on the surface of a manganite by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Vasudevan, Rama K.; Tselev, Alexander; Gianfrancesco, Anthony G.; Baddorf, Arthur P.; Kalinin, Sergei V.

    2015-04-01

    The doped manganese oxides (manganites) have been widely studied for their colossal magnetoresistive effects, for potential applications in oxide spintronics, electroforming in resistive switching devices, and are materials of choice as cathodes in modern solid oxide fuel cells. However, little experimental knowledge of the dynamics of the surfaces of perovskite manganites at the atomic scale exists. Here, through in-situ scanning tunneling microscopy (STM), we demonstrate atomic resolution on samples of La0.625Ca0.375MnO3 grown on (001) SrTiO3 by pulsed laser deposition. Furthermore, by applying triangular DC waveforms of increasing amplitude to the STM tip, and measuring the tunneling current, we demonstrate the ability to both perform and monitor surface electrochemical processes at the atomic level, including formation of oxygen vacancies and removal and deposition of individual atomic units or clusters. Our work paves the way for better understanding of surface oxygen reactions in these systems.

  16. Probing magnetization dynamics in individual magnetite nanocrystals using magnetoresistive scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Hevroni, Amir; Tsukerman, Boris; Markovich, Gil

    2015-12-01

    The magnetization dynamics of individual magnetite nanocrystals was probed by variable-temperature magnetoresistive scanning tunneling microscopy, in which a magnetoresistive junction is formed between the substrate and the magnetic particle under study. By tuning the temperature close to the magnetization blocking of a superparamagnetic particle, the slow magnetization switching of the particle caused fluctuations in the tunnel current passing through the particle, which appeared as telegraph noise in current vs time measurements. Analysis of the current fluctuations yielded estimates for the low local magnetic field sensed by the particle, its magnetic anisotropy energy, and the low limit for the spin-polarization degree of the nanocrystals, which for some particles appeared to be as high as 90%.

  17. Highlighting functional groups in self-assembled overlayers with specific functionalized scanning tunnelling microscopy tips

    NASA Astrophysics Data System (ADS)

    Volcke, Cedric; Simonis, Priscilla; Thiry, Paul A.; Lambin, Philippe; Culot, Christine; Humbert, Christophe

    2005-11-01

    Overlayers of a fatty acid (palmitic and lauric acid) formed at the interface between a solution of this molecule in phenyloctane and the basal plane of graphite are studied by in situ scanning tunnelling microscopy. The layers organize into lamellae, which are formed by a close packing arrangement of molecules parallel to the graphite surface. Chemical modification of the STM tips used allowed identification of the functional group. Indeed, the gold tips used are functionalized with 4-mercaptobenzoic acid (4-MBA) and 4-mercaptotoluene (4-MT). The same functional group on a sample is then 'seen' as a dark and a bright spot when imaged with 4-MBA and 4-MT modified tips, respectively. This contrast distinction is related to interactions (or a lack of them) between the carboxyl group on the sample and molecules on the tip, which can facilitate (or hinder) the electron tunnelling.

  18. Development of a detachable high speed miniature scanning probe microscope for large area substrates inspection

    SciTech Connect

    Sadeghian, Hamed E-mail: h.sadeghianmarnani@tudelft.nl; Herfst, Rodolf; Winters, Jasper; Crowcombe, Will; Kramer, Geerten; Dool, Teun van den; Es, Maarten H. van

    2015-11-15

    We have developed a high speed, miniature scanning probe microscope (MSPM) integrated with a Positioning Unit (PU) for accurately positioning the MSPM on a large substrate. This combination enables simultaneous, parallel operation of many units on a large sample for high throughput measurements. The size of the MSPM is 19 × 45 × 70 mm{sup 3}. It contains a one-dimensional flexure stage with counter-balanced actuation for vertical scanning with a bandwidth of 50 kHz and a z-travel range of more than 2 μm. This stage is mechanically decoupled from the rest of the MSPM by suspending it on specific dynamically determined points. The motion of the probe, which is mounted on top of the flexure stage is measured by a very compact optical beam deflection (OBD). Thermal noise spectrum measurements of short cantilevers show a bandwidth of 2 MHz and a noise of less than 15 fm/Hz{sup 1/2}. A fast approach and engagement of the probe to the substrate surface have been achieved by integrating a small stepper actuator and direct monitoring of the cantilever response to the approaching surface. The PU has the same width as the MSPM, 45 mm and can position the MSPM to a pre-chosen position within an area of 275×30 mm{sup 2} to within 100 nm accuracy within a few seconds. During scanning, the MSPM is detached from the PU which is essential to eliminate mechanical vibration and drift from the relatively low-resonance frequency and low-stiffness structure of the PU. Although the specific implementation of the MSPM we describe here has been developed as an atomic force microscope, the general architecture is applicable to any form of SPM. This high speed MSPM is now being used in a parallel SPM architecture for inspection and metrology of large samples such as semiconductor wafers and masks.

  19. Scanning tunneling microscopy and spectroscopy measurements of superconductor/ferromagnet hybrids

    NASA Astrophysics Data System (ADS)

    Moore, Steven A.

    The focus of this thesis work is the study of the nanoscale electronic properties of magnetically coupled superconductor/ferromagnet hybrid structures using low-temperature scanning tunneling microscopy and spectroscopy (LT-STM/STS) under ultra-high vacuum conditions. There are a number of novel effects that can occur due to the non-homogenous magnetic field from the ferromagnet, which directly influence the global and local superconducting properties. These effects include the generation of vortices/anti-vortices by the non-uniform magnetic stray field, local modulations in the critical temperature, filamentary superconductivity close to the transition temperature, and superconducting channels that can be controlled by external magnetic fields. Prior to this dissertation the subject of superconductor/ferromagnet hybrid structures has been mainly studied using global measurements (such as transport and magnetization) or scanning probe techniques that are sensitive to the magnetic field. Scanning tunneling microscopy probes the local electronic density of states with atomic resolution, and therefore is the only technique that can study the emergence of superconductivity on the length scale of the coherence length. The novel results presented in this dissertation show that magnetically coupled superconductor/ferromagnet heterostructures offer the possibility to control and tune the strength and location of superconductivity and superconducting vortices, which has potential for promising technological breakthroughs in computing and power applications.

  20. Development of a scanning tunneling potentiometry system for measurement of electronic transport at short length scales

    NASA Astrophysics Data System (ADS)

    Rozler, Michael

    It is clear that complete understanding of macroscopic properties of materials is impossible without a thorough knowledge of behavior at the smallest length scales. While the past 25 years have witnessed major advances in a variety of techniques that probe the nanoscale properties of matter, electrical transport measurements -- the heart of condensed matter research -- have lagged behind, never progressing beyond bulk measurements. This thesis describes a scanning tunneling potentiometry (STP) system developed to simultaneously map the transport-related electrochemical potential distribution of a biased sample along with its surface topography, extending electronic transport measurements to the nanoscale. Combining a novel sample biasing technique with a continuous current-nulling feedback scheme pushes the noise performance of the measurement to its fundamental limit - the Johnson noise of the STM tunnel junction. The resulting 130 nV voltage sensitivity allows us to spatially resolve local potentials at scales down to 2 nm, while maintaining atomic scale STM imaging, all at scan sizes of up to 15 microns. A mm-range two-dimensional coarse positioning stage and the ability to operate from liquid helium to room temperature with a fast turn-around time greatly expand the versatility of the instrument. Use of carefully selected model materials, combined with excellent topographic and voltage resolution has allowed us to distinguish measurement artifacts caused by surface roughness from true potentiometric features, a major problem in previous STP measurements. The measurements demonstrate that STP can produce physically meaningful results for homogeneous transport as well as non-uniform conduction dominated by material microstructures. Measurements of several physically interesting materials systems are presented as well, revealing new behaviors at the smallest length sales. The results establish scanning tunneling potentiometry as a useful tool for physics and

  1. Scanning tunneling microscopy studies of vapor deposited films of tetrathiafulvalene with iodine

    NASA Astrophysics Data System (ADS)

    Breen, J. J.; Tolman, J. S.; Flynn, G. W.

    1993-03-01

    Scanning tunneling microscopy studies are reported for vacuum deposited conducting films of tetrathiafulvalene (TTF) with iodine (I) codeposited on mica substrates. Molecular resolution images reveal a crystal structure consistent with that of single crystals of a material with chemical composition (TTF)7I5 with the crystal c axis parallel to the plane of the mica substrate. The imaged surface is terminated with TTF molecules, and the submicron dimension crystal planes which are observed reveal surface steps consistent with the layered and stacked nature characteristic of charge transfer salt materials.

  2. Topographical investigations of human ovarian-carcinoma polymorphic epithelial mucin by scanning tunnelling microscopy.

    PubMed Central

    Roberts, C J; Sekowski, M; Davies, M C; Jackson, D E; Price, M R; Tendler, S J

    1992-01-01

    Human polymorphic epithelial mucin is a high-molecular-mass glycoprotein that associates to provide protection to the epithelial-cell surface and may afford the malignant cell a selective advantage for growth. The scanning-tunnelling-microscopy micrographs obtained in the present study identify the purified human ovarian-carcinoma polymorphic epithelial mucin glycoproteins as rod-shaped molecules of mixed length. The dimensions of the individual molecules range from 25 to 45 nm in length and are 3-4 nm in width. The images further suggest that lateral association of the rods occurs. Images Fig. 1. Fig. 2. PMID:1567366

  3. An automatic method for atom identification in scanning tunnelling microscopy images of Fe-chalcogenide superconductors.

    PubMed

    Perasso, A; Toraci, C; Massone, A M; Piana, M; Gerbi, A; Buzio, R; Kawale, S; Bellingeri, E; Ferdeghini, C

    2015-12-01

    We describe a computational approach for the automatic recognition and classification of atomic species in scanning tunnelling microscopy images. The approach is based on a pipeline of image processing methods in which the classification step is performed by means of a Fuzzy Clustering algorithm. As a representative example, we use the computational tool to characterize the nanoscale phase separation in thin films of the Fe-chalcogenide superconductor FeSex Te1-x , starting from synthetic data sets and experimental topographies. We quantify the stoichiometry fluctuations on length scales from tens to a few nanometres. PMID:26291960

  4. An automatic method for atom identification in scanning tunnelling microscopy images of Fe-chalcogenide superconductors.

    PubMed

    Perasso, A; Toraci, C; Massone, A M; Piana, M; Gerbi, A; Buzio, R; Kawale, S; Bellingeri, E; Ferdeghini, C

    2015-12-01

    We describe a computational approach for the automatic recognition and classification of atomic species in scanning tunnelling microscopy images. The approach is based on a pipeline of image processing methods in which the classification step is performed by means of a Fuzzy Clustering algorithm. As a representative example, we use the computational tool to characterize the nanoscale phase separation in thin films of the Fe-chalcogenide superconductor FeSex Te1-x , starting from synthetic data sets and experimental topographies. We quantify the stoichiometry fluctuations on length scales from tens to a few nanometres.

  5. Low-temperature scanning tunneling microscopy and spectroscopy measurements of ultrathin Pb films

    NASA Astrophysics Data System (ADS)

    Moore, S. A.; Fedor, J.; Iavarone, M.

    2015-04-01

    We have investigated the electronic properties of ultrathin Pb films by low temperature scanning tunneling microscopy and spectroscopy. Our results show that 30 nm thick Pb(111) films grown on atomically flat highly oriented pyrolytic graphite (HOPG) and on amorphous SiO2 are both in the strong-coupling limit with transition temperature and energy gap close to the bulk value. Conductance maps and spectroscopy in the vortex state reveal a bound state at the center of the vortices, which suggest that the films are in the clean limit. Measurements of 3 nm Pb films grown on HOPG show a clear crossover to the weak-coupling regime and dirty limit.

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

    SciTech Connect

    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.

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

    PubMed

    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.

  8. Tracking the subsurface path of dislocations in GaN using scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Weidlich, P. H.; Schnedler, M.; Portz, V.; Eisele, H.; Strauß, U.; Dunin-Borkowski, R. E.; Ebert, Ph.

    2015-07-01

    A methodology for the determination of the subsurface line direction of dislocations using scanning tunneling microscopy (STM) images is presented. The depth of the dislocation core is derived from an analysis of the displacement field measured by STM. The methodology is illustrated for dislocations at GaN( 10 1 ¯ 0 ) cleavage surfaces. It is found that the dislocation line bends toward the surface, changing from predominantly edge-type to more screw-type character, when approaching the intersection point. Simultaneously, the total displacement detectable at the surface increases due to a preferred relaxation towards the surface.

  9. How to reveal metastable skyrmionic spin structures by spin-polarized scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Dupé, B.; Kruse, C. N.; Dornheim, T.; Heinze, S.

    2016-05-01

    We predict the occurrence of metastable skyrmionic spin structures such as antiskyrmions and higher-order skyrmions in ultra-thin transition-metal films at surfaces using Monte Carlo simulations based on a spin Hamiltonian parametrized from density functional theory calculations. We show that such spin structures will appear with a similar contrast in spin-polarized scanning tunneling microscopy images. Both skyrmions and antiskyrmions display a circular shape for out-of-plane magnetized tips and a two-lobe butterfly contrast for in-plane tips. An unambiguous distinction can be achieved by rotating the tip magnetization direction without requiring the information of all components of the magnetization.

  10. Adsorbate-induced quantum Hall system probed by scanning tunneling spectroscopy combined with transport measurements

    SciTech Connect

    Masutomi, Ryuichi Okamoto, Tohru

    2015-06-22

    An adsorbate-induced quantum Hall system at the cleaved InSb surfaces is investigated in magnetic fields up to 14 T using low-temperature scanning tunneling microscopy and spectroscopy combined with transport measurements. We show that an enhanced Zeeman splitting in the Shubnikov-de Haas oscillations is explained by an exchange enhancement of spin splitting and potential disorder, both of which are obtained from the spatially averaged density of states (DOS). Moreover, the Altshuler–Aronov correlation gap is observed in the spatially averaged DOS at 0 T.

  11. Origin of electrically heterogeneous microstructure in CuO from scanning tunneling spectroscopy study

    NASA Astrophysics Data System (ADS)

    Sarkar, Sudipta; Jana, Pradip Kumar; Chaudhuri, B. K.

    2008-04-01

    We report electronic structure of the grains and grain boundaries (GBs) of the high permittivity (κ˜104) ceramic CuO from scanning tunneling spectroscopy (STS) studies. The p-type semiconducting character of the CuO grains and insulating behavior of the corresponding GBs, observed from STS studies, have been explained. This type of electrically inhomogeneous microstructure leads to the formation of barrier layer capacitance elements in CuO and, hence, provides an explanation of the colossal-κ response exhibited by CuO.

  12. Scanning tunneling microscopy of superconducting topological surface states in Bi2Se3

    NASA Astrophysics Data System (ADS)

    Dayton, Ian M.; Sedlmayr, Nicholas; Ramirez, Victor; Chasapis, Thomas C.; Loloee, Reza; Kanatzidis, Mercouri G.; Levchenko, Alex; Tessmer, Stuart H.

    2016-06-01

    In this Rapid Communication we present scanning tunneling microscopy of a large Bi2Se3 crystal with superconducting PbBi islands deposited on the surface. Local density of states measurements are consistent with induced superconductivity in the topological surface state with a coherence length of order 540 nm. At energies above the gap the density of states exhibits oscillations due to scattering caused by a nonuniform order parameter. Strikingly, the spectra taken on islands also display similar oscillations along with traces of the Dirac cone, suggesting an inverse topological proximity effect.

  13. Electron Damage to Supported Ice Investigated by Scanning Tunneling Microscopy and Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mehlhorn, Michael; Gawronski, Heiko; Morgenstern, Karina

    2008-11-01

    We study the interaction of low-energy electrons with crystalline ice (D2O) on Cu(111) by low-temperature scanning tunneling microscopy and spectroscopy. Electrons induce dissociation of the molecules with a threshold of ≈3eV. The large dissociation yield of the order of 10-8/electron and the extended area of dissociation are attributed to a shift in conduction band during the dissociation. Voltage dependent differences in imaging of ice and dissociated ice are reflected in the spectroscopic signature.

  14. Applying deep learning technology to automatically identify metaphase chromosomes using scanning microscopic images: an initial investigation

    NASA Astrophysics Data System (ADS)

    Qiu, Yuchen; Lu, Xianglan; Yan, Shiju; Tan, Maxine; Cheng, Samuel; Li, Shibo; Liu, Hong; Zheng, Bin

    2016-03-01

    Automated high throughput scanning microscopy is a fast developing screening technology used in cytogenetic laboratories for the diagnosis of leukemia or other genetic diseases. However, one of the major challenges of using this new technology is how to efficiently detect the analyzable metaphase chromosomes during the scanning process. The purpose of this investigation is to develop a computer aided detection (CAD) scheme based on deep learning technology, which can identify the metaphase chromosomes with high accuracy. The CAD scheme includes an eight layer neural network. The first six layers compose of an automatic feature extraction module, which has an architecture of three convolution-max-pooling layer pairs. The 1st, 2nd and 3rd pair contains 30, 20, 20 feature maps, respectively. The seventh and eighth layers compose of a multiple layer perception (MLP) based classifier, which is used to identify the analyzable metaphase chromosomes. The performance of new CAD scheme was assessed by receiver operation characteristic (ROC) method. A number of 150 regions of interest (ROIs) were selected to test the performance of our new CAD scheme. Each ROI contains either interphase cell or metaphase chromosomes. The results indicate that new scheme is able to achieve an area under the ROC curve (AUC) of 0.886+/-0.043. This investigation demonstrates that applying a deep learning technique may enable to significantly improve the accuracy of the metaphase chromosome detection using a scanning microscopic imaging technology in the future.

  15. Efficient method for fast simulation of scanning tunneling microscopy with a tip effect.

    PubMed

    Zhang, Ruiqi; Hu, Zhenpeng; Li, Bin; Yang, Jinlong

    2014-10-01

    On the basis of Bardeen's perturbation theory on electron tunneling and inspired by Paz et al.'s study, a new expression for the tunneling current between the scanning tunneling microscopy (STM) tip and sample has been obtained, and it provides us with an efficient method to simulate STM images. The method can be implemented in any code of first-principles computing software, which offers the wave functions of the tip and sample, calculated independently at the same footing, as input. By calculating the integral with fast Fourier transform (FFT), simulating the STM image of a given sample surface by a database of different tips on a PC turns out to be not a time-consuming work. Compared with Paz et al.'s method, our method abandons the application of the vacuum Green function and possesses better computing efficiency, fewer parameters, and more reasonable simulated results especially at lower computing cost. Simple tip-sample systems, such as H-H and Pd2-Ag2, are taken as benchmarks to test our method. The topographic images of a CO molecule adsorbed on a Cu(111) surface obtained by using a tungsten tip and a CO-terminated tip are also simulated, and the simulated results are in good agreement with the experimental ones. PMID:24708199

  16. Wind Tunnel Testing of a One-Dimensional Laser Beam Scanning and Laser Sheet Approach to Shock Sensing

    NASA Technical Reports Server (NTRS)

    Tokars, Roger; Adamovsky, Grigory; Anderson, Robert; Hirt, Stefanie; Huang, John; Floyd, Bertram

    2012-01-01

    A 15- by 15-cm supersonic wind tunnel application of a one-dimensional laser beam scanning approach to shock sensing is presented. The measurement system design allowed easy switching between a focused beam and a laser sheet mode for comparison purposes. The scanning results were compared to images from the tunnel Schlieren imaging system. The tests revealed detectable changes in the laser beam in the presence of shocks. The results lend support to the use of the one-dimensional scanning beam approach for detecting and locating shocks in a flow, but some issues must be addressed in regards to noise and other limitations of the system.

  17. Scanning Tunneling Microscopy and Spectroscopy of the Heavy Fermion Compounds URu2 Si 2 and CeCoIn5

    NASA Astrophysics Data System (ADS)

    Aynajian, Pegor

    2011-03-01

    Heavy electronic states originating from the f atomic orbitals underlie a rich variety of quantum phases of matter. We use atomic scale imaging and spectroscopy with the scanning tunneling microscope (STM) to examine the novel electronic states that emerge from the uranium f states in URu 2 Si 2. We find that as the temperature is lowered, partial screening of the f electrons' spins gives rise to a spatially modulated Kondo-Fano resonance that is maximal between the surface U atoms. At T=17.5 K, URu 2 Si 2 is known to undergo a 2nd order phase transition from the Kondo lattice state into a phase with a hidden order parameter. From tunneling spectroscopy, we identify a spatially modulated, bias-asymmetric energy gap with a mean-field temperature dependence that develops in the hidden order state. Spectroscopic imaging further reveals a spatial correlation between the hidden order gap and the Kondo resonance, suggesting that the two phenomena involve the same electronic states. We further study the behavior of the Kondo lattice in a model heavy fermion compound CeCoIn 5 as a function of temperature and establish a direct comparison between the two heavy fermion compounds. This work is funded by a DOE-BES grant. Infrastructure at the Princeton Nanoscale Microscopy Laboratory are also supported by grants from NSF-DMR, Keck Foundation, and NSF-MRSEC. PA also acknowledges support of a fellowship through the PCCM funded by NSF MERSEC. Work done in collaboration with Eduardo H. da Silva Neto, Colin V. Parker, Yingkai Huang, Abhay Pasupathy, John Mydosh, Eric Bauer, Paul Tobash, and Ali Yazdani.

  18. Quantitative description of photoexcited scanning tunneling spectroscopy and its application to the GaAs(110) surface

    NASA Astrophysics Data System (ADS)

    Schnedler, M.; Portz, V.; Weidlich, P. H.; Dunin-Borkowski, R. E.; Ebert, Ph.

    2015-06-01

    A quantitative description of photoexcited scanning tunneling spectra is developed and applied to photoexcited spectra measured on p -doped nonpolar GaAs(110) surfaces. Under illumination, the experimental spectra exhibit an increase of the tunnel current at negative sample voltages only. In order to analyze the experimental data quantitatively, the potential and charge-carrier distributions of the photoexcited tip-vacuum-semiconductor system are calculated by solving the Poisson as well as the hole and electron continuity equations by a finite-difference algorithm. On this basis, the different contributions to the tunnel current are calculated using an extension of the model of Feenstra and Stroscio to include the light-excited carrier concentrations. The best fit of the calculated tunnel currents to the experimental data is obtained for a tip-induced band bending, which is limited by the partial occupation of the C3 surface state by light-excited electrons. The tunnel current at negative voltages is then composed of a valence band contribution and a photoinduced tunnel current of excited electrons in the conduction band. The quantitative description of the tunnel current developed here is generally applicable and provides a solid foundation for the quantitative interpretation of photoexcited scanning tunneling spectroscopy.

  19. Fabrication of [001]-oriented tungsten tips for high resolution scanning tunneling microscopy

    PubMed Central

    Chaika, A. N.; Orlova, N. N.; Semenov, V. N.; Postnova, E. Yu.; Krasnikov, S. A.; Lazarev, M. G.; Chekmazov, S. V.; Aristov, V. Yu.; Glebovsky, V. G.; Bozhko, S. I.; Shvets, I. V.

    2014-01-01

    The structure of the [001]-oriented single crystalline tungsten probes sharpened in ultra-high vacuum using electron beam heating and ion sputtering has been studied using scanning and transmission electron microscopy. The electron microscopy data prove reproducible fabrication of the single-apex tips with nanoscale pyramids grained by the {011} planes at the apexes. These sharp, [001]-oriented tungsten tips have been successfully utilized in high resolution scanning tunneling microscopy imaging of HOPG(0001), SiC(001) and graphene/SiC(001) surfaces. The electron microscopy characterization performed before and after the high resolution STM experiments provides direct correlation between the tip structure and picoscale spatial resolution achieved in the experiments. PMID:24434734

  20. Renormalization of the graphene dispersion velocity determined from scanning tunneling spectroscopy.

    PubMed

    Chae, Jungseok; Jung, Suyong; Young, Andrea F; Dean, Cory R; Wang, Lei; Gao, Yuanda; Watanabe, Kenji; Taniguchi, Takashi; Hone, James; Shepard, Kenneth L; Kim, Phillip; Zhitenev, Nikolai B; Stroscio, Joseph A

    2012-09-14

    In graphene, as in most metals, electron-electron interactions renormalize the properties of electrons but leave them behaving like noninteracting quasiparticles. Many measurements probe the renormalized properties of electrons right at the Fermi energy. Uniquely for graphene, the accessibility of the electrons at the surface offers the opportunity to use scanned probe techniques to examine the effect of interactions at energies away from the Fermi energy, over a broad range of densities, and on a local scale. Using scanning tunneling spectroscopy, we show that electron interactions leave the graphene energy dispersion linear as a function of excitation energy for energies within ±200  meV of the Fermi energy. However, the measured dispersion velocity depends on density and increases strongly as the density approaches zero near the charge neutrality point, revealing a squeezing of the Dirac cone due to interactions.