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Sample records for scanning magnetoresistance microscopy

  1. Domain wall magnetoresistance in BiFeO3 thin films measured by scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Domingo, N.; Farokhipoor, S.; Santiso, J.; Noheda, B.; Catalan, G.

    2017-08-01

    We measure the magnetotransport properties of individual 71° domain walls in multiferroic BiFeO3 by means of conductive—atomic force microscopy (C-AFM) in the presence of magnetic fields up to one Tesla. The results suggest anisotropic magnetoresistance at room temperature, with the sign of the magnetoresistance depending on the relative orientation between the magnetic field and the domain wall plane. A consequence of this finding is that macroscopically averaged magnetoresistance measurements for domain wall bunches are likely to underestimate the magnetoresistance of each individual domain wall.

  2. Domain wall magnetoresistance in BiFeO3 thin films measured by scanning probe microscopy.

    PubMed

    Domingo, N; Farokhipoor, S; Santiso, J; Noheda, B; Catalan, G

    2017-08-23

    We measure the magnetotransport properties of individual 71° domain walls in multiferroic BiFeO3 by means of conductive-atomic force microscopy (C-AFM) in the presence of magnetic fields up to one Tesla. The results suggest anisotropic magnetoresistance at room temperature, with the sign of the magnetoresistance depending on the relative orientation between the magnetic field and the domain wall plane. A consequence of this finding is that macroscopically averaged magnetoresistance measurements for domain wall bunches are likely to underestimate the magnetoresistance of each individual domain wall.

  3. Photothermal imaging scanning microscopy

    DOEpatents

    Chinn, Diane; Stolz, Christopher J.; Wu, Zhouling; Huber, Robert; Weinzapfel, Carolyn

    2006-07-11

    Photothermal Imaging Scanning Microscopy produces a rapid, thermal-based, non-destructive characterization apparatus. Also, a photothermal characterization method of surface and subsurface features includes micron and nanoscale spatial resolution of meter-sized optical materials.

  4. Scanning ultrafast electron microscopy.

    PubMed

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

    2010-08-24

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

  5. Scanning ultrafast electron microscopy

    PubMed Central

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

    2010-01-01

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability. PMID:20696933

  6. Photon scanning tunneling microscopy

    SciTech Connect

    Goudonnet, J.P.; Salomon, L.; De Fornel, F.; Chabrier, G. . Lab. de Physique du Solide); Warmack, R.J.; Ferrell, T.L. )

    1990-01-01

    The Photon Scanning Tunneling Microscopy (PSTM) is the photon analogue of the electron Scanning Tunneling Microscope (STM). It uses the evanescent field due to the total internal reflection of a light beam in a Total Internal Reflection (TIR) prism. The sample, mounted on the base of the prism, modulates the evanescent field. A sharpened optical fiber probes this field, and the collected light is processed to generate an image of the topography and the chemical composition of the surface. We give, in this paper, a description of the microscope and discuss the influence of several parameters such as -- polarization of light, angle of incidence, shape of the end of the fiber -- on the resolution. Images of various samples -- glass samples, teflon spheres -- are presented. 8 refs., 7 figs.

  7. Ultrafast scanning probe microscopy

    DOEpatents

    Weiss, Shimon; Chemla, Daniel S.; Ogletree, D. Frank; Botkin, David

    1995-01-01

    An ultrafast scanning probe microscopy method for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample.

  8. Ultrafast scanning probe microscopy

    DOEpatents

    Weiss, S.; Chemla, D.S.; Ogletree, D.F.; Botkin, D.

    1995-05-16

    An ultrafast scanning probe microscopy method is described for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample. 6 Figs.

  9. 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.

  10. Photon scanning tunneling microscopy

    SciTech Connect

    Reddick, R.C.; Warmack, R.J.; Chilcott, D.W.; Sharp, S.L.; Ferrell, T.L. Department of Physics and Astronomy, University of Tennessee, Knoxville, TN )

    1990-12-01

    An optical tunneling microscope is presented that operates in exactly the same way as the electron scanning tunneling microscope (ESTM). It takes advantage of evanescent fields generated by the total internal reflection (TIR) of light at the interface between materials of different optical densities. The photon scanning tunneling microscope (PSTM) employs an optically conducting probe tip to map spatial variations in the evanescent and scattered field intensity distributions adjacent to a sample surface, which forms or is placed on the TIR surface. These variations are due to the local topography, morphology, and optical activity of the surface and form the basis of imaging. Evanescent field theory is discussed and the evanescent field intensity as a function of surface-probe separation is calculated using several probe tip models. After a description of PSTM construction and operation, evanescent field intensity measurements are shown to agree with the model calculations. PSTM images of various sample surfaces demonstrate subwavelength resolution exceeding that of conventional optical microscopy, especially in the vertical dimension. Limitations and interpretation of PSTM images are discussed as well as the PSTMs applicability to other forms of surface analysis.

  11. Rotational scanning atomic force microscopy.

    PubMed

    Ulčinas, A; Vaitekonis, Š

    2017-03-10

    A non-raster scanning technique for atomic force microscopy (AFM) imaging which combines rotational and translational motion is presented. The use of rotational motion for the fast scan axis allows us to significantly increase the scanning speed while imaging a large area (diameter > 30 μm). An image reconstruction algorithm and the factors influencing the resolution of the technique are discussed. The experimental results show the potential of the rotational scanning technique for high-throughput large area AFM investigation.

  12. Rotational scanning atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Ulčinas, A.; Vaitekonis, Š.

    2017-03-01

    A non-raster scanning technique for atomic force microscopy (AFM) imaging which combines rotational and translational motion is presented. The use of rotational motion for the fast scan axis allows us to significantly increase the scanning speed while imaging a large area (diameter > 30 μm). An image reconstruction algorithm and the factors influencing the resolution of the technique are discussed. The experimental results show the potential of the rotational scanning technique for high-throughput large area AFM investigation.

  13. Optical scanning holographic microscopy

    NASA Astrophysics Data System (ADS)

    Poon, Ting-Chung; Doh, Kyu B.; Schilling, Bradley W.; Wu, Ming H.; Shinoda, Kazunori K.; Suzuki, Yoshiji

    1995-03-01

    We first review a newly developed 3D imaging technique called optical scanning holography (OSH), and discuss recording and reconstruction of a point object using the principle of OSH. We then derive 3D holographic magnification, using three points configured as a 3D object. Finally, we demonstrated 3D imaging capability of OSH by holographically recording two planar objects at different depths and reconstructing the hologram digitally.

  14. Studies in Scanning Probe Microscopy.

    DTIC Science & Technology

    2007-11-02

    refereed journals, as well as two books titled Scanning Force Microscopy, With Applications to Electric, Magnetic, and Atomic Forces published by Oxford University Press in 1991 and a revised edition in 1994.

  15. Studies in scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Sarid, Dror

    1995-06-01

    The following is a final report on our work in the field of Scanning Probe Microscopy (SPM), which has been funded by the AFOSR under Contract #F49620-92-J-0164. The AFOSR funding was instrumental in the establishment of a multi-lab facility at the Optical Sciences Center, which performs research in SPM using two ultrahigh vacuum (UHV) STM facilities, and several Atomic Force Microscopy (AFM) facilities. The fabrication and characterization work performed in the SPM Laboratory is supplemented by infrared (IR) spectroscopy, high resolution transmission electron microscopy (HRTEM), and scanning electron microscopy (SEM), available in other departments on campus. The report covers the following areas: (1) GaAs and CdSe Structures, (2) Optical Interactions on a nm and nsec Scales, (3) Fullerenes on Gold, (4) Fullerenes on MoS2, (5) Fullerenes on Si, (6) SiC, (7) Nanotubes, (8) Scanning Force Microscopy, and (9) Biology.

  16. Scanning Quantum Dot Microscopy

    NASA Astrophysics Data System (ADS)

    Wagner, Christian; Green, Matthew F. B.; Leinen, Philipp; Deilmann, Thorsten; Krüger, Peter; Rohlfing, Michael; Temirov, Ruslan; Tautz, F. Stefan

    2015-07-01

    We introduce a scanning probe technique that enables three-dimensional imaging of local electrostatic potential fields with subnanometer resolution. Registering single electron charging events of a molecular quantum dot attached to the tip of an atomic force microscope operated at 5 K, equipped with a qPlus tuning fork, we image the quadrupole field of a single molecule. To demonstrate quantitative measurements, we investigate the dipole field of a single metal adatom adsorbed on a metal surface. We show that because of its high sensitivity the technique can probe electrostatic potentials at large distances from their sources, which should allow for the imaging of samples with increased surface roughness.

  17. [Confocal laser scanning microscopy].

    PubMed

    Ulrich, M

    2015-07-01

    Reflectance confocal microscopy (RCM) allows the in vivo evaluation of melanocytic and nonmelanocytic skin tumours with high sensitivity and specificity. RCM represents an optical imaging technique, which enables us to examine the skin at high resolution. Today, RCM represents not only an interesting tool for dermatologic research but has also been introduced as a diagnostic tool in every day clinical practice. As such, RCM is applied for improvement of skin cancer diagnosis adjunct to clinical and dermatoscopic examination. In combination with dermatoscopy RCM has shown an increased specificity with similar sensitivity. In this regard RCM helps to decrease the rate of unnecessary biopsies of benign lesions. Despite its use in dermatooncology RCM may also be used for diagnosis and monitoring of inflammatory diseases. Future developments include technical improvements, teledermatology solutions and the application of ex vivo RCM in Moh's micrographic surgery.

  18. Research With Scanning Tip Microscopy

    DTIC Science & Technology

    1991-12-31

    08ro P noiwe bae?041Le Research With Scanning Tip Microscopy AFOSR-89-0498 V AUTHOS)i Professor Dror Sarid 7. PFOUImNG 00ANIZATION NAMEIS) AND...forces and (b) surfaces. UNCLASS UNCLASS UNCLASS UL FINAL REPORT TO THE AFOSR ൱-, to J4ti. r Aat io Research in Scanning Tip Microscopy Dror Sarid Dtst...microscopy have been used to investigate (a) forces and (b) surfaces. a. Forces 1. Dror Sarid , Douglas lams, Volker Weissenberger, and L. Stephen Bell

  19. Vertically scanned laser sheet microscopy.

    PubMed

    Dong, Di; Arranz, Alicia; Zhu, Shouping; Yang, Yujie; Shi, Liangliang; Wang, Jun; Shen, Chen; Tian, Jie; Ripoll, Jorge

    2014-01-01

    Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distribution of a fluorescence signal in fixed tissue or small organisms. In laser sheet microscopy, the stripe artifacts caused by high absorption or high scattering structures are very common, greatly affecting image quality. To solve this problem, we report here a two-step procedure which consists of continuously acquiring laser sheet images while vertically displacing the sample, and then using the variational stationary noise remover (VSNR) method to further reduce the remaining stripes. Images from a cleared murine colon acquired with a vertical scan are compared with common stitching procedures demonstrating that vertically scanned light sheet microscopy greatly improves the performance of current light sheet microscopy approaches without the need for complex changes to the imaging setup and allows imaging of elongated samples, extending the field of view in the vertical direction.

  20. Scanning Probe Microscopy Markup Language

    NASA Astrophysics Data System (ADS)

    Bolhuis, T.; Pasop, J. R.; Abelmann, L.; Lodder, J. C.

    2003-12-01

    The numerous, proprietary file formats for Scanning Probe Microscopy (SPM) have caused problems in the field of both off-line quantitative, data analysis and comparison, as well as long-term archiving of measurement results. Because of the eminent roll SPM's are playing in the multidisciplinary scientific world of today, an open, XML-based, standard SPM data format, called Scanning Probe Microscopy Markup Language (SPML) is proposed. XML (eXtensible Markup Language) has proven to be well applicable for standardized, structured, scientific data formats in many other disciplines. The structure of SPML will be explained briefly. The versatility of SPML as well as the possibilities of documenting, publishing, searching and exchanging SPM-data will be shown in examples. This paper gives an overview of the proposed data format, while the complete description can be found at http://spml.net.

  1. Scanning probe microscopy in catalysis.

    PubMed

    Yeung, King Lun; Yao, Nan

    2004-09-01

    This review discusses the recent progress in the application of scanning probe microscopy (SPM) in catalysis. SPM proves to be an invaluable technique for imaging catalytic surfaces and interfaces. Most SPM research is related to the structural and morphological transformation associated with catalyst preparation and use. Real-time SPM observation of surface dynamics including adsorption, diffusion and reaction, provides invaluable insights to the mechanism of catalysis. SPM is also used to shape and manipulate surfaces and surface processes. Fabrication of nanostructured catalysts, direct manipulation of adsorbed atoms and molecules and tip-mediated reactions are some examples of new SPM approach in catalyst research.

  2. Aperture scanning Fourier ptychographic microscopy

    PubMed Central

    Ou, Xiaoze; Chung, Jaebum; Horstmeyer, Roarke; Yang, Changhuei

    2016-01-01

    Fourier ptychographic microscopy (FPM) is implemented through aperture scanning by an LCOS spatial light modulator at the back focal plane of the objective lens. This FPM configuration enables the capturing of the complex scattered field for a 3D sample both in the transmissive mode and the reflective mode. We further show that by combining with the compressive sensing theory, the reconstructed 2D complex scattered field can be used to recover the 3D sample scattering density. This implementation expands the scope of application for FPM and can be beneficial for areas such as tissue imaging and wafer inspection. PMID:27570705

  3. Differential Multiphoton Laser Scanning Microscopy

    SciTech Connect

    Field, Jeffrey J.; Sheetz, Kraig E.; Chandler, Eric V.; Hoover, Erich E.; Young, Michael D.; Ding, Shi-you; Sylvester, Anne W.; Kleinfeld, David; Squier, Jeff A.

    2012-01-01

    Multifocal multiphoton laser scanning microscopy (mfMPLSM) in the biological and medical sciences has the potential to become a ubiquitous tool for obtaining high-resolution images at video rates. While current implementations of mfMPLSM achieve very high frame rates, they are limited in their applicability to essentially those biological samples that exhibit little or no scattering. In this paper, we report on a method for mfMPLSM in which whole-field detection with a single detector, rather than detection with a matrix of detectors, such as a charge-coupled device (CCD) camera, is implemented. This advance makes mfMPLSM fully compatible for use in imaging through scattering media. Further, we demonstrate that this method makes it possible to simultaneously obtain multiple images and view differences in excitation parameters in a single scan of the specimen.

  4. Thermal radiation scanning tunnelling microscopy.

    PubMed

    De Wilde, Yannick; Formanek, Florian; Carminati, Rémi; Gralak, Boris; Lemoine, Paul-Arthur; Joulain, Karl; Mulet, Jean-Philippe; Chen, Yong; Greffet, Jean-Jacques

    2006-12-07

    In standard near-field scanning optical microscopy (NSOM), a subwavelength probe acts as an optical 'stethoscope' to map the near field produced at the sample surface by external illumination. This technique has been applied using visible, infrared, terahertz and gigahertz radiation to illuminate the sample, providing a resolution well beyond the diffraction limit. NSOM is well suited to study surface waves such as surface plasmons or surface-phonon polaritons. Using an aperture NSOM with visible laser illumination, a near-field interference pattern around a corral structure has been observed, whose features were similar to the scanning tunnelling microscope image of the electronic waves in a quantum corral. Here we describe an infrared NSOM that operates without any external illumination: it is a near-field analogue of a night-vision camera, making use of the thermal infrared evanescent fields emitted by the surface, and behaves as an optical scanning tunnelling microscope. We therefore term this instrument a 'thermal radiation scanning tunnelling microscope' (TRSTM). We show the first TRSTM images of thermally excited surface plasmons, and demonstrate spatial coherence effects in near-field thermal emission.

  5. Scanning Electrochemical Microscopy in Neuroscience

    NASA Astrophysics Data System (ADS)

    Schulte, Albert; Nebel, Michaela; Schuhmann, Wolfgang

    2010-07-01

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

  6. Image scanning microscopy with radially polarized light

    NASA Astrophysics Data System (ADS)

    Xiao, Yun; Zhang, Yunhai; Wei, Tongda; Huang, Wei; Shi, Yaqin

    2017-03-01

    In order to improve the resolution of image scanning microscopy, we present a method based on image scanning microscopy and radially polarized light. According to the theory of image scanning microscopy, we get the effective point spread function of image scanning microscopy with the longitudinal component of radially polarized light and a 1 AU detection area, and obtain imaging results of the analyzed samples using this method. Results show that the resolution can be enhanced by 7% compared with that in image scanning microscopy with circularly polarized light, and is 1.54-fold higher than that in confocal microscopy with a pinhole of 1 AU. Additionally, the peak intensity of ISM is 1.54-fold higher than that of a confocal microscopy with a pinhole of 1 AU. In conclusion, the combination of the image scanning microscopy and the radially polarized light could improve the resolution, and it could realize high-resolution and high SNR imaging at the same time.

  7. Scanning Tunneling Optical Resonance Microscopy

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila; Wilt, Dave; Raffaelle, Ryne; Gennett, Tom; Tin, Padetha; Lau, Janice; Castro, Stephanie; Jenkins, Philip; Scheiman, Dave

    2003-01-01

    Scanning tunneling optical resonance microscopy (STORM) is a method, now undergoing development, for measuring optoelectronic properties of materials and devices on the nanoscale by means of a combination of (1) traditional scanning tunneling microscopy (STM) with (2) tunable laser spectroscopy. In STORM, an STM tip probing a semiconductor is illuminated with modulated light at a wavelength in the visible-to-near-infrared range and the resulting photoenhancement of the tunneling current is measured as a function of the illuminating wavelength. The photoenhancement of tunneling current occurs when the laser photon energy is sufficient to excite charge carriers into the conduction band of the semiconductor. Figure 1 schematically depicts a proposed STORM apparatus. The light for illuminating the semiconductor specimen at the STM would be generated by a ring laser that would be tunable across the wavelength range of interest. The laser beam would be chopped by an achromatic liquid-crystal modulator. A polarization-maintaining optical fiber would couple the light to the tip/sample junction of a commercial STM. An STM can be operated in one of two modes: constant height or constant current. A STORM apparatus would be operated in the constant-current mode, in which the height of the tip relative to the specimen would be varied in order to keep the tunneling current constant. In this mode, a feedback control circuit adjusts the voltage applied to a piezoelectric actuator in the STM that adjusts the height of the STM tip to keep the tunneling current constant. The exponential relationship between the tunneling current and tip-to-sample distance makes it relatively easy to implement this mode of operation. The choice of method by which the photoenhanced portion of the tunneling current would be measured depends on choice of the frequency at which the input illumination would be modulated (chopped). If the frequency of modulation were low enough (typically < 10 Hz) that the

  8. Scanning Tip Microscopy With Applications To Biology

    NASA Astrophysics Data System (ADS)

    Sarid, Dror; Thall, Edmond H.; Iams, Douglas A.; Ingle, Jeffery T.; Henson, Tammy D.; Lee, Y. C.; Bell, L. Stephen

    1989-06-01

    Scanning tunneling microscopy and atomic force microscopy, denoted here scanning tip microscopy, are two powerful novel techniques for imaging surfaces with atomic resolution. We describe the underlying principles of these two techniques with special emphasis on an instrument developed in our laboratory that uses a laser diode to detect minute deflections of a tip as it raster scans the surface of a sample. Applications of these techniques to research in biology are assessed and their relative merits discussed.

  9. Scanning Tunneling Microscopy Studies of Quasicrystals

    NASA Astrophysics Data System (ADS)

    Becker, Russell S.; Kortan, A. Refik

    The following sections are included: * INTRODUCTION * EXPERIMENTAL * X-RAY DIFFRACTION * SCANNING TUNNELING MICROSCOPY * STRUCTURE MODELLING BASED ON STM * COMPARISON WITH MODELS BASED ON BULK STUDIES * CONCLUSION * REFERENCES

  10. Enhanced effects with scanning force microscopy

    NASA Astrophysics Data System (ADS)

    Howells, S.; Chen, T.; Gallagher, M.; Yi, L.; Sarid, D.

    1991-05-01

    A general theory that describes the operation of scanning force microscopy in the contact force regime is presented. It is shown that force derivatives along the surface of a sample produce images that can be dramatically enhanced relative to those of surface topography. For scanning tunneling microscopy atomic force microscopy configurations, the spring constant of the cantilever and the force derivatives perpendicular to the surface of the sample determine the enhancement, respectively.

  11. Scanning Optical Microscopy Applied To Fluorometry

    NASA Astrophysics Data System (ADS)

    Roblin, Gerard; Bernstein, Leon

    1987-08-01

    Scanning Optical Microscopy, able to reconstruct, pixel after pixel, low noise images with the expected microscope resolution, is especially suitable for quantitative microscopy. Use of a bright, monochromatic spot of light extends its field of application to fluo-rescence Microscopy. Description of a typical device is given and the problems encountered to realize the scan of the laser beam are discussed. Results relating to transmitted light images as well as to epifluorescence images and spectral analysis are shown.

  12. Re-scan confocal microscopy: scanning twice for better resolution

    PubMed Central

    De Luca, Giulia M.R.; Breedijk, Ronald M.P.; Brandt, Rick A.J.; Zeelenberg, Christiaan H.C.; de Jong, Babette E.; Timmermans, Wendy; Azar, Leila Nahidi; Hoebe, Ron A.; Stallinga, Sjoerd; Manders, Erik M.M.

    2013-01-01

    We present a new super-resolution technique, Re-scan Confocal Microscopy (RCM), based on standard confocal microscopy extended with an optical (re-scanning) unit that projects the image directly on a CCD-camera. This new microscope has improved lateral resolution and strongly improved sensitivity while maintaining the sectioning capability of a standard confocal microscope. This simple technology is typically useful for biological applications where the combination high-resolution and high-sensitivity is required. PMID:24298422

  13. Differential Multiphoton Laser Scanning Microscopy

    PubMed Central

    Field, Jeffrey J.; Sheetz, Kraig E.; Chandler, Eric V.; Hoover, Erich E.; Young, Michael D.; Ding, Shi-you; Sylvester, Anne W.; Kleinfeld, David; Squier, Jeff A.

    2016-01-01

    Multifocal multiphoton microscopy (MMM) in the biological and medical sciences has become an important tool for obtaining high resolution images at video rates. While current implementations of MMM achieve very high frame rates, they are limited in their applicability to essentially those biological samples that exhibit little or no scattering. In this paper, we report on a method for MMM in which imaging detection is not necessary (single element point detection is implemented), and is therefore fully compatible for use in imaging through scattering media. Further, we demonstrate that this method leads to a new type of MMM wherein it is possible to simultaneously obtain multiple images and view differences in excitation parameters in a single shot. PMID:27390511

  14. Rotary-scanning optical resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Qi, Weizhi; Xi, Lei

    2016-10-01

    Optical resolution photoacoustic microscopy (ORPAM) is currently one of the fastest evolving photoacoustic imaging modalities. It has a comparable spatial resolution to pure optical microscopic techniques such as epifluorescence microscopy, confocal microscopy, and two-photon microscopy, but also owns a deeper penetration depth. In this paper, we report a rotary-scanning (RS)-ORPAM that utilizes a galvanometer scanner integrated with objective to achieve rotary laser scanning. A 15 MHz cylindrically focused ultrasonic transducer is mounted onto a motorized rotation stage to follow optical scanning traces synchronously. To minimize the loss of signal to noise ratio, the acoustic focus is precisely adjusted to reach confocal with optical focus. Black tapes and carbon fibers are firstly imaged to evaluate the performance of the system, and then in vivo imaging of vasculature networks inside the ears and brains of mice is demonstrated using this system.

  15. 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.

  16. Theoretical simulation of scanning probe microscopy.

    PubMed

    Tsukada, Masaru

    2011-01-01

    Methods of theoretical simulation of scanning probe microscopy, including scanning tunneling microscopy (STM), atomic force microscopy(AFM) and Kelvin prove force microscopy (KPFM) have been reviewed with recent topics as case studies. For the case of the STM simulation, the importance of the tip electronic states is emphasized and some advanced formalism is presented based on the non-equilibrium Green's function theory beyond Bardeen's perturbation theory. For the simulation of AFM, we show examples of 3D-force map for AFM in water, and theoretical analyses for a nano-mechanical experiment on a protein molecule. An attempt to simulate KPFM images based on the electrostatic multi-pole interaction between a tip and a sample is also introduced.

  17. (Gene sequencing by scanning molecular exciton microscopy)

    SciTech Connect

    Not Available

    1991-01-01

    This report details progress made in setting up a laboratory for optical microscopy of genes. The apparatus including a fluorescence microscope, a scanning optical microscope, various spectrometers, and supporting computers is described. Results in developing photon and exciton tips, and in preparing samples are presented. (GHH)

  18. Scanning electron microscopy study of Trichomonas gallinae.

    PubMed

    Tasca, Tiana; De Carli, Geraldo A

    2003-12-01

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

  19. Exploring Scanning Probe Microscopy with Mathematica

    NASA Astrophysics Data System (ADS)

    Sarid, Dror

    1997-10-01

    This book/software edition provides a complete set of computational models that describe the physical phenomena associated with scanning tunneling microscopy, atomic force microscopy, and related technologies. Its self-contained presentation spares researchers the valuable time spent hunting through the technical literature in search of prior theoretical results required to understand the models presented. Mathematica code for all examples is included both in the book and at the accompanying ftp site, affording the freedom to change, at will, the values and parameters of specific problems or even modify the programs themselves to suit various modeling needs. Exploring Scanning Probe Microscopy with Mathematica is both a solid professional reference and an advanced-level text, beginning with scanning probe microscopy basics and moving on to cutting-edge techniques, experiments, and theory. In the section devoted to atomic force microscopy, Dr. Sarid describes the mechanical properties of cantilevers, atomic force microscope tip-sample interactions, and cantilever vibration characteristics. This is followed by an in-depth treatment of theoretical and practical aspects of tunneling phenomena, including metal-insulator-metal tunneling and Fowler-Nordheim field emission. The final section features chapters covering density of states in arbitrary dimensions, quantum wells and dots, and electrostatics.

  20. Environmental scanning electron microscopy in cell biology.

    PubMed

    McGregor, J E; Staniewicz, L T L; Guthrie Neé Kirk, S E; Donald, A M

    2013-01-01

    Environmental scanning electron microscopy (ESEM) (1) is an imaging technique which allows hydrated, insulating samples to be imaged under an electron beam. The resolution afforded by this technique is higher than conventional optical microscopy but lower than conventional scanning electron microscopy (CSEM). The major advantage of the technique is the minimal sample preparation needed, making ESEM quick to use and the images less susceptible to the artifacts that the extensive sample preparation usually required for CSEM may introduce. Careful manipulation of both the humidity in the microscope chamber and the beam energy are nevertheless essential to prevent dehydration and beam damage artifacts. In some circumstances it is possible to image live cells in the ESEM (2).In the following sections we introduce the fundamental principles of ESEM imaging before presenting imaging protocols for plant epidermis, mammalian cells, and bacteria. In the first two cases samples are imaged using the secondary electron (topographic) signal, whereas a transmission technique is employed to image bacteria.

  1. Surface Studies by Scanning Probe Microscopy

    NASA Astrophysics Data System (ADS)

    Kim, Ho-Seob

    The scanning probe microscopy reported here includes scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and atomic force microscopy (AFM). The scanning tunneling microscope is a novel tool which can reveal the atomic structure and electronic properties of surfaces using a probe with a sharp tip. An additional technique, atomic force microscopy has the potential to record geometric structures for both conducting and non -conducting materials. The first AFM designs utilized short range forces between a small stylus and a sample surface to produce high resolution images of defects and structural features of the surface. The current-voltage characteristics were also investigated during dynamic changes of the tunnel current and barrier height with an additional technology, tunneling spectroscopy. An advanced design for an AFM has been developed which utilizes a dielectric tunnel junction to retain the high sensitivity of tunnel current control over force ranges between 10^{-6} and 10 ^{-11}N. This AFM has been successfully applied to physical and biological samples. Scanning probe techniques have been developed and applied to a range of sample types including conductors, semi-conductors and non-conductors. Each technique utilizes the same electronics, computers, and imaging facilities. A fundamental problem of the atomic structure of graphite has existed since the inception of STM images. The experimental and theoretical hypotheses have been considered and a resolution of the problem has been developed as reported in this dissertation. Unprecedented resolving power, greater than 1A, has confirmed our hypothesis and has been correctly correlated with the structure of graphite surface. This dissertation also presents the results from studies of the surface structure of: MoS_2 , Cu, Au, Ag, Si, CdTe, HgTe, Fe_2 O_3, mica, gypsum, purple membranes with protein chains, and an organic photoconducting material, by scanning probe microscopes.

  2. Nanoscale thermometry by scanning thermal microscopy

    NASA Astrophysics Data System (ADS)

    Menges, Fabian; Riel, Heike; Stemmer, Andreas; Gotsmann, Bernd

    2016-07-01

    Measuring temperature is a central challenge in nanoscience and technology. Addressing this challenge, we report the development of a high-vacuum scanning thermal microscope and a method for non-equilibrium scanning probe thermometry. The microscope is built inside an electromagnetically shielded, temperature-stabilized laboratory and features nanoscopic spatial resolution at sub-nanoWatt heat flux sensitivity. The method is a dual signal-sensing technique inferring temperature by probing a total steady-state heat flux simultaneously to a temporally modulated heat flux signal between a self-heated scanning probe sensor and a sample. Contact-related artifacts, which so far limit the reliability of nanoscopic temperature measurements by scanning thermal microscopy, are minimized. We characterize the microscope's performance and demonstrate the benefits of the new thermometry approach by studying hot spots near lithographically defined constrictions in a self-heated metal interconnect.

  3. Aberration corrected Lorentz scanning transmission electron microscopy.

    PubMed

    McVitie, S; McGrouther, D; McFadzean, S; MacLaren, D A; O'Shea, K J; Benitez, M J

    2015-05-01

    We present results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment. We discuss the innovations in microscope instrumentation and additional hardware that underpin the imaging improvements in resolution and detection with a focus on developments in differential phase contrast microscopy. Examples from materials possessing nanometre scale variations in magnetisation illustrate the potential for aberration corrected Lorentz imaging as a tool to further our understanding of magnetism on this lengthscale.

  4. Scanning Electron Microscopy Sample Preparation and Imaging.

    PubMed

    Nguyen, Jenny Ngoc Tran; Harbison, Amanda M

    2017-01-01

    Scanning electron microscopes allow us to reach magnifications of 20-130,000× and resolve compositional and topographical images with intense detail. These images are created by bombarding a sample with electrons in a focused manner to generate a black and white image from the electrons that bounce off of the sample. The electrons are detected using positively charged detectors. Scanning electron microscopy permits three-dimensional imaging of desiccated specimens or wet cells and tissues by using variable pressure chambers. SEM ultrastructural analysis and intracellular imaging supplement light microscopy for molecular profiling of prokaryotes, plants, and mammals. This chapter demonstrates how to prepare and image samples that are (a) desiccated and conductive, (b) desiccated and nonconductive but coated with an electron conductive film using a gold sputter coater, and (c) wet and maintained in a hydrated state using a Deben Coolstage.

  5. Observation of Superlubricity by Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Hirano, Motohisa; Shinjo, Kazumasa; Kaneko, Reizo; Murata, Yoshitada

    1997-02-01

    Experimental evidence of superlubricity, the state of vanishing friction, is obtained by examining systems of sliding atomically clean surfaces by using ultrahigh vacuum scanning tunneling microscopy. The experimental results agree with theoretical predictions: Friction is not observed in the superlubricity regime in measurements capable of resolving a friction force of 3×10-9 N, whereas friction of 8×10-8 N, which is comparable to theoretical values, is observed in the friction regime.

  6. Scanning electron microscopy of superficial white onychomycosis*

    PubMed Central

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

    2015-01-01

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

  7. Scanning Ion Conductance Microscopy of Live Keratinocytes

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  8. Feature Adaptive Sampling for Scanning Electron Microscopy

    PubMed Central

    Dahmen, Tim; Engstler, Michael; Pauly, Christoph; Trampert, Patrick; de Jonge, Niels; Mücklich, Frank; Slusallek, Philipp

    2016-01-01

    A new method for the image acquisition in scanning electron microscopy (SEM) was introduced. The method used adaptively increased pixel-dwell times to improve the signal-to-noise ratio (SNR) in areas of high detail. In areas of low detail, the electron dose was reduced on a per pixel basis, and a-posteriori image processing techniques were applied to remove the resulting noise. The technique was realized by scanning the sample twice. The first, quick scan used small pixel-dwell times to generate a first, noisy image using a low electron dose. This image was analyzed automatically, and a software algorithm generated a sparse pattern of regions of the image that require additional sampling. A second scan generated a sparse image of only these regions, but using a highly increased electron dose. By applying a selective low-pass filter and combining both datasets, a single image was generated. The resulting image exhibited a factor of ≈3 better SNR than an image acquired with uniform sampling on a Cartesian grid and the same total acquisition time. This result implies that the required electron dose (or acquisition time) for the adaptive scanning method is a factor of ten lower than for uniform scanning. PMID:27150131

  9. Near Field Scanning Optical Microscopy (NSOM)

    PubMed Central

    Betzig, E.; Lewis, A.; Harootunian, A.; Isaacson, M.; Kratschmer, E.

    1986-01-01

    A new method for high-resolution imaging, near-field scanning optical microscopy (NSOM), has been developed. The concepts governing this method are discussed, and the technical challenges encountered in constructing a working NSOM instrument are described. Two distinct methods are presented for the fabrication of well-characterized, highly reproducible, subwavelength apertures. A sample one-dimensional scan is provided and compared to the scanning electron micrograph of a test pattern. From this comparison, a resolution of > 1,500 Å (i.e., ≃λ/3.6) is determined, which represents a significant step towards our eventual goal of 500 Å resolution. Fluorescence has been observed through apertures smaller than 600 Å and signal-to-noise calculations show that fluorescent imaging should be feasible. The application of such imaging is then discussed in reference to specific biological problems. The NSOM method employs nonionizing visible radiation and can be used in air or aqueous environments for nondestructive visualization of functioning biological systems with a resolution comparable to that of scanning electron microscopy. ImagesFIGURE 4FIGURE 7FIGURE 9FIGURE 10 PMID:19431633

  10. Near-Field Scanning Optical Microscopy and Raman Microscopy.

    NASA Astrophysics Data System (ADS)

    Harootunian, Alec Tate

    1987-09-01

    Both a one dimensional near-field scanning optical microscope and Raman microprobe were constructed. In near -field scanning optical microscopy (NSOM) a subwavelength aperture is scanned in the near-field of the object. Radiation transmitted through the aperture is collected to form an image as the aperture scans over the object. The resolution of an NSOM system is essentially wavelength independent and is limited by the diameter of the aperture used to scan the object. NSOM was developed in an effort to provide a nondestructive in situ high spatial resolution probe while still utilizing photons at optical wavelengths. The Raman microprobe constructed provided vibrational Raman information with spatial resolution equivalent that of a conventional diffraction limited microscope. Both transmission studies and near-field diffration studies of subwavelength apertures were performed. Diffraction theories for a small aperture in an infinitely thin conducting screen, a slit in a thick conducting screen, and an aperture in a black screen were examined. All three theories indicate collimation of radiation to the size to the size of the subwavelength aperture or slit in the near-field. Theoretical calculations and experimental results indicate that light transmitted through subwavelength apertures is readily detectable. Light of wavelength 4579 (ANGSTROM) was transmitted through apertures with diameters as small as 300 (ANGSTROM). These studies indicate the feasibility of constructing an NSOM system. One dimensional transmission and fluorescence NSOM systems were constructed. Apertures in the tips of metallized glass pipettes width inner diameters of less than 1000 (ANGSTROM) were used as a light source in the NSOM system. A tunneling current was used to maintain the aperture position in the near-field. Fluorescence NSOM was demonstrated for the first time. Microspectroscopic and Raman microscopic studies of turtle cone oil droplets were performed. Both the Raman vibrational

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

    PubMed Central

    Davis, Brynmor. J.; Marks, Daniel. L.; Ralston, Tyler. S.; Carney, P. Scott; Boppart, Stephen. A.

    2008-01-01

    Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM) allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT), utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR). In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR. PMID:20948975

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

    PubMed

    Davis, Brynmor J; Marks, Daniel L; Ralston, Tyler S; Carney, P Scott; Boppart, Stephen A

    2008-06-01

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

  13. Scanning Probe Microscopy of Organic Solar Cells

    NASA Astrophysics Data System (ADS)

    Reid, Obadiah G.

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

  14. 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.

  15. 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

  16. Intermittent contact hydration scanning probe microscopy.

    PubMed

    Aloisi, G; Bacci, F; Carlà, M; Dolci, D

    2010-07-01

    Hydration scanning probe microscopy is a technique similar to scanning tunneling microscopy, in which the probe current, sustained by the slight surface conduction of a thin hydration layer covering an insulating support surface, is essentially electrochemical in nature instead of electronic tunneling. Such a technique allows the imaging of a great variety of samples, including insulators, provided that they are hydrophilic, as well as the study of molecular samples of biological interest (such as DNA) fixed on a suitable supporting surface. The main problem to obtain stable and reproducible images comes from the very critical determination of the operating conditions under which the probe-hydration layer interaction does not lead to the formation of a relatively large water meniscus. It has been suggested that this issue can be removed by adding a high frequency oscillation to the probe movement, as in tapping atomic force microscopy. Meniscus formation and breakup have been investigated in order to determine the best values for the amplitude and the frequency of the oscillation. Results obtained in this mode are discussed in comparison with the usual continuous contact mode.

  17. Immunogold Labeling for Scanning Electron Microscopy.

    PubMed

    Goldberg, Martin W; Fišerová, Jindřiška

    2016-01-01

    Scanning electron microscopes are useful biological tools that can be used to image the surface of whole organisms, tissues, cells, cellular components, and macromolecules. Processes and structures that exist at surfaces can be imaged in pseudo, or real 3D at magnifications ranging from about 10× to 1,000,000×. Therefore a whole multicellular organism, such as a fly, or a single protein embedded in one of its cell membranes can be visualized. In order to identify that protein at high resolution, or to see and quantify its distribution at lower magnifications, samples can be labeled with antibodies. Any surface that can be exposed can potentially be studied in this way. Presented here is a generic method for immunogold labeling for scanning electron microscopy, using two examples of specimens: isolated nuclear envelopes and the cytoskeleton of mammalian culture cells. Various parameters for sample preparation, fixation, immunogold labeling, drying, metal coating, and imaging are discussed so that the best immunogold scanning electron microscopy results can be obtained from different types of specimens.

  18. Immunogold labelling for scanning electron microscopy.

    PubMed

    Goldberg, Martin W; Fiserova, Jindriska

    2010-01-01

    Scanning electron microscopes are useful biological tools that can be used to image the surface of whole organisms, tissues, cells, cellular components and macromolecules. Processes and structures that exist at surfaces can be imaged in pseudo or real 3D at magnifications of anything from about x10 to x1,000,000. Therefore a whole multicellular organism, such as a fly, or a single protein embedded in one of its cell membranes can be visualised. In order to identify that protein at high resolution, or to see and quantify its distribution at lower magnifications, samples can be labelled with antibodies. Any surface that can be exposed can potentially be studied in this way. Presented here is a generic method for immunogold labelling for scanning electron microscopy, using two examples of specimens: isolated nuclear envelopes and the cytoskeleton of mammalian culture cells. Various parameters for sample preparation, fixation, immunogold labelling, drying, metal coating and imaging are discussed so that the best immunogold scanning electron microscopy results can be obtained from different types of specimens.

  19. Optical microscopy versus scanning electron microscopy in urolithiasis.

    PubMed

    Marickar, Y M Fazil; Lekshmi, P R; Varma, Luxmi; Koshy, Peter

    2009-10-01

    Stone analysis is incompletely done in many clinical centers. Identification of the stone component is essential for deciding future prophylaxis. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy (SEM) still remains a distant dream for routine hospital work. It is in this context that optical microscopy is suggested as an alternate procedure. The objective of this article was to assess the utility of an optical microscope which gives magnification of up to 40x and gives clear picture of the surface of the stones. In order to authenticate the morphological analysis of urinary stones, SEM and elemental distribution analysis were performed. A total of 250 urinary stones of different compositions were collected from stone clinic, photographed, observed under an optical microscope, and optical photographs were taken at different angles. Twenty-five representative samples among these were gold sputtered to make them conductive and were fed into the SEM machine. Photographs of the samples were taken at different angles at magnifications up to 4,000. Elemental distribution analysis (EDAX) was done to confirm the composition. The observations of the two studies were compared. The different appearances of the stones under optical illuminated microscopy were mostly standardized appearances, namely bosselations of pure whewellite, spiculations of weddellite, bright yellow colored appearance of uric acid, and dirty white amorphous appearance of phosphates. SEM and EDAX gave clearer pictures and gave added confirmation of the stone composition. From the references thus obtained, it was possible to confirm the composition by studying the optical microscopic pictures. Higher magnification capacity of the SEM and the EDAX patterns are useful to give reference support for performing optical microscopy work. After standardization, routine analysis can be performed with optical microscopy. The advantage of the optical microscope is that, it

  20. Scanning electron microscopy of lichen sclerosus*

    PubMed Central

    de Almeida, Hiram Larangeira; Bicca, Eduardo de Barros Coelho; Breunig, Juliano de Avelar; Rocha, Nara Moreira; Silva, Ricardo Marques e

    2013-01-01

    Lichen sclerosus is an acquired inflammatory condition characterized by whitish fibrotic plaques, with a predilection for the genital skin. We performed scanning electron microscopy of the dermis from a lesion of lichen sclerosus. Normal collagen fibers could be easily found in deeper layers of the specimen, as well as the transition to pathologic area, which seems homogenized. With higher magnifications in this transitional area collagen fibers are adherent to each other, and with very high magnifications a pearl chain aspect became evident along the collagen fibers. In the superficial dermis this homogenization is even more evident, collagen fibers are packed together and round structures are also observed. Rupture of collagen fibers and inflammatory cells were not found. These autoimmune changes of the extracellular matrix lead to the aggregation of immune complexes and/or changed matrix proteins along the collagen fibers, the reason why they seem hyalinized when examined by light microscopy. PMID:23739707

  1. Global standardization of scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Fujita, Daisuke; Itoh, Hiroshi; Ichimura, Shingo; Kurosawa, Tomizo

    2007-02-01

    Recent efforts to achieve global standardization of scanning probe microscopy (SPM) including noncontact atomic force microscopy (NC-AFM), especially through the International Organization for Standardization (ISO) and related research, are surveyed. Since the unification of terminology for SPM is a prerequisite for standardization, it should have the first priority, followed by the unification of data management and treatment, which will enable access to and processing of SPM data collected by different types of instrument. Among the various SPM analytical methods, the dimensional metrology of SPM is regarded to be the first priority for standardization. This requires solving two basic problems: calibrating the x, y, and z coordinate axes with traceability to the SI unit of length, and eliminating the morphological artefacts caused by the shape of the probe tip. Pre-standardization efforts on restoring distorted images and characterizing the tip shape during use are discussed.

  2. Scanning Electron Microscopy of the Presbylarynx.

    PubMed

    Gonçalves, Tatiana Maria; Dos Santos, Daniela Carvalho; Pessin, Adriana Bueno Benito; Martins, Regina Helena Garcia

    2016-06-01

    To describe the findings on the presbylarynx under scanning electron microscopy. Cadaver study. Universidade Estadual Paulista (Botucatu, São Paulo, Brazil). Sixteen vocal folds were removed during necropsies and distributed into 2 age groups: control (n = 8; aged 30-50 years) and elderly (n = 8; aged 75-92 years). The right vocal fold was dissected, fixed in glutaraldehyde 2.5%, and prepared for scanning electron microscopy. The thickness of the epithelium was measured using a scandium morphometric digital program. In the control group, the epithelium had 5 to 7 overlapped cell layers, rare desquamation cells, and little undulation with protruding intercellular junctions. The lamina propria showed a uniform network of collagen and elastic fibers in the superficial layer. A dense network of collagen was identified in the deeper layer. In the elderly group, the epithelium was atrophic (2-3 cells), with more desquamation cells and intercellular junctions delimited by deep sulci. The epithelial thickness was lower in elderly than in controls (mean [SD], 221.64 [145.90] µm vs 41.79 [21.40] µm, respectively). The lamina propria had a dense and irregular distribution of collagen and elastic fibers in the superficial layer. In the deep layers, the collagen fibers formed a true fibrotic and rigid skeleton. Scanning electron microscopy identified several changes in the elderly larynx, differentiating it from the controls. These alterations are probably related to the aging process of the vocal folds. However, the exact interpretation of these findings requires additional studies, even to the molecular level, having the fibroblasts as targets. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

  3. Scanning electron microscopy study of Tritrichomonas augusta.

    PubMed

    Borges, Fernanda P; Wiltuschnig, Renata C M; Tasca, Tiana; De Carli, Geraldo A

    2004-09-01

    Tritrichomonas augusta is a flagellated protozoan that parasitizes amphibians and reptiles. According to scanning electron microscopy (SEM), the cell shape of T. augusta varies from slender pyriform to ovoidal. Our data show the morphological features of the trophozoites: the emergence of the anterior flagella, the structure of the undulating membrane and the position and shape of the pelta, axostyle and posterior flagellum. In addition, herein we describe spherical forms which are probably pseudocysts. The description of the external structure of T. augusta, as demonstrated by SEM, contributes to the understanding of the biology of this parasite.

  4. Scanning electron microscopy studies of bacterial cultures

    NASA Astrophysics Data System (ADS)

    Swinger, Tracy; Blust, Brittni; Calabrese, Joseph; Tzolov, Marian

    2012-02-01

    Scanning electron microscopy is a powerful tool to study the morphology of bacteria. We have used conventional scanning electron microscope to follow the modification of the bacterial morphology over the course of the bacterial growth cycle. The bacteria were fixed in vapors of Glutaraldehyde and ruthenium oxide applied in sequence. A gold film of about 5 nm was deposited on top of the samples to avoid charging and to enhance the contrast. We have selected two types of bacteria Alcaligenes faecalis and Kocuria rhizophila. Their development was carefully monitored and samples were taken for imaging in equal time intervals during their cultivation. These studies are supporting our efforts to develop an optical method for identification of the Gram-type of bacterial cultures.

  5. Scanning probe microscopy investigation of bilayered manganites

    NASA Astrophysics Data System (ADS)

    Huang, Junwei

    The bilayered manganite La2-2xSr 1+2xMn2O7, with x in the ferromagnetic compositional region, exhibits very interesting electronic and magnetic properties below the Curie temperature, such as a colossal magneto-resistance (CMR) effect. We have studied the microscopic electronic structure in the x = 0.32, 0.4 compounds at 80 K and 20 K by using a home-built low temperature scanning tunneling microscope (STM) and the evolution of the ferromagnetic domains with temperature and magnetic field in the x = 0.32 compound from 30 K to 110 K by using a home-built low temperature magnetic force microscope (MFM). STM topographic images show nano-sized patterns composed of Mn 3+-rich and Mn4+-rich regions in the mixed-valent matrix. Tunneling spectra I(V)& dIdV (V) show a gap and a tunneling asymmetry of the LDOS as a function of the sample bias voltage. By using current-imaging tunneling spectroscopy (CITS), we obtained a series of tunneling conductance maps which show the coexistence of localized electrons and itinerant electrons in this system. In the x = 0.32 compound, we observed a modulation with a wave vector of 16 A propagating along a-axis at 20K. This indicates the formation of a charge density wave as a result of Fermi surface nesting in this system. In MFM images, we observed that below 60 K, the ferromagnetic (FM) domains form stable treelike patterns and the domains are mainly oriented in the out-of-plane direction. As the temperature increases, the FM domains begin to experience a gradual change. This change becomes more and more rapid above 80 K. The FM domains change their magnetization from the out-of-plane direction to in-plane around 88 K. The in-plane FM domains completely disappear near T C. We also observed thermal hysteresis occurring in magnetic structures. We conclude that the formation of FM domains at low temperatures is determined by the energy associated with surface magnetic free poles and domain walls. At high temperatures, the two

  6. Two-Photon Laser Scanning Microscopy

    NASA Astrophysics Data System (ADS)

    Nimmerjahn, A.; Theer, P.; Helmchen, F.

    Since its inception more than 15 years ago, two-photon laser scanning microscopy (2PLSM) has found widespread use in biological and medical research. Two-photon microscopy is based on simultaneous absorption of two photons by fluorophores and subsequent fluorescence emission, a process which under normal illumination conditions is highly improbable. Theoretically described around 1930 by Maria Göppert-Mayer [1], the first experimental demonstration of two-photon excitation had to await the invention of the laser, which produced sufficiently high light intensities to observe two-photon absorption events [2]. Only after the development of ultrafast lasers providing subpicosecond light pulses with high peak power intensities, however, two-photon-excited fluorescence became practical in a laser-scanning microscope [3]. Since then 2PLSM has developed into the method of choice for high-resolution imaging in living animals (reviewed in [4,5]). One of the main reasons is the low sensitivity of 2PLSM to light scattering, which enables imaging relatively deep inside biological tissue and direct observation of the dynamic behavior of cells in their native environment. In this chapter, we introduce the physical principles governing 2PLSM and briefly describe the key instrument components. We give an overview of fluorescence labeling techniques and how they are combined with 2PLSM for functional imaging and photomanipulation in living tissue. Finally, we discuss limitations and provide some future perspectives.

  7. Two-Photon Laser Scanning Microscopy

    NASA Astrophysics Data System (ADS)

    Nimmerjahn, A.; Theer, P.; Helmchen, F.

    Since its inception more than 15 years ago, two-photon laser scanning microscopy (2PLSM) has found widespread use in biological and medical research. Two-photon microscopy is based on simultaneous absorption of two photons by fluorophores and subsequent fluorescence emission, a process which under normal illumination conditions is highly improbable. Theoretically described around 1930 by Maria Göppert-Mayer [1], the first experimental demonstration of two-photon excitation had to await the invention of the laser, which produced sufficiently high light intensities to observe two-photon absorption events [2]. Only after the development of ultrafast lasers providing subpicosecond light pulses with high peak power intensities, however, two-photon-excited fluorescence became practical in a laser-scanning microscope [3]. Since then 2PLSM has developed into the method of choice for high-resolution imaging in living animals (reviewed in [4,5]). One of the main reasons is the low sensitivity of 2PLSM to light scattering, which enables imaging relatively deep inside biological tissue and direct observation of the dynamic behavior of cells in their native environment. In this chapter, we introduce the physical principles governing 2PLSM and briefly describe the key instrument components. We give an overview of fluorescence labeling techniques and how they are combined with 2PLSM for functional imaging and photomanipulation in living tissue. Finally, we discuss limitations and provide some future perspectives.

  8. Scanning probe microscopy of protein nanowires

    NASA Astrophysics Data System (ADS)

    Walsh, Kathleen Ann

    The bacterium Geobacter sulfurreducens grows electrically-conductive pili, which act as protein nanowires, in order to transfer electrons from the cell to electron acceptors in its environment when direct charge transfer through the cell membrane is not feasible. Understanding the electronic structure of the pili can provide insight into fundamental processes of electron transfer in biological systems. This study investigated the electronic structure of these protein nanowires using the toolbox of scanning probe microscopy, specifically scanning tunneling microscopy and point tunneling spectroscopy. These measurements were performed at 77 K and at room temperature. The measured data are compared to theoretical calculations. Density of states measurements using tunneling spectroscopy show that these pili act as narrow-gap biological semiconductors at 77 K. The onset of nonzero density of states remains within the metabolically-relevant voltage range. At room temperature, spectroscopy of the pili retains a gap-like structure, but this pseudogap is raised to a nonzero density of states at even the smallest applied voltages. These pilus nanowires also exhibit a distinct spatial dependence of the density of states across the breadth of the pili.

  9. Video-rate resonant scanning multiphoton microscopy

    PubMed Central

    Kirkpatrick, Nathaniel D.; Chung, Euiheon; Cook, Daniel C.; Han, Xiaoxing; Gruionu, Gabriel; Liao, Shan; Munn, Lance L.; Padera, Timothy P.; Fukumura, Dai; Jain, Rakesh K.

    2013-01-01

    The abnormal tumor microenvironment fuels tumor progression, metastasis, immune suppression, and treatment resistance. Over last several decades, developments in and applications of intravital microscopy have provided unprecedented insights into the dynamics of the tumor microenvironment. In particular, intravital multiphoton microscopy has revealed the abnormal structure and function of tumor-associated blood and lymphatic vessels, the role of aberrant tumor matrix in drug delivery, invasion and metastasis of tumor cells, the dynamics of immune cell trafficking to and within tumors, and gene expression in tumors. However, traditional multiphoton microscopy suffers from inherently slow imaging rates—only a few frames per second, thus unable to capture more rapid events such as blood flow, lymphatic flow, and cell movement within vessels. Here, we report the development and implementation of a video-rate multiphoton microscope (VR-MPLSM) based on resonant galvanometer mirror scanning that is capable of recording at 30 frames per second and acquiring intravital multispectral images. We show that the design of the system can be readily implemented and is adaptable to various experimental models. As examples, we demonstrate the utility of the system to directly measure flow within tumors, capture metastatic cancer cells moving within the brain vasculature and cells in lymphatic vessels, and image acute responses to changes in a vascular network. VR-MPLSM thus has the potential to further advance intravital imaging and provide new insight into the biology of the tumor microenvironment. PMID:24353926

  10. Phase-contrast scanning transmission electron microscopy.

    PubMed

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

    2015-06-01

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

  11. Imaging quantum transport using scanning gate microscopy

    NASA Astrophysics Data System (ADS)

    Hackens, Benoit

    2014-03-01

    Quantum transport in nanodevices is usually probed thanks to measurements of the electrical resistance or conductance, which lack the spatial resolution necessary to probe electron behaviour inside the devices. In this talk, we will show that scanning gate microscopy (SGM) yields real-space images of quantum transport phenomena inside archetypal mesoscopic devices such as quantum point contacts and quantum rings. We will first discuss the SGM technique, which is based on mapping the electrical conductance of a device as an electrically-biased sharp metallic tip scans in its vicinity. With SGM, we demonstrated low temperature imaging of the electron probability density and interferences in embedded mesoscopic quantum rings [B. Hackens et al., Nat. Phys. 2, 826 (2006)]. At high magnetic field, thanks to the SGM conductance maps, one can decrypt complex transport phenomena such as tunneling between quantum Hall edge state, either direct or through localized states [B. Hackens et al., Nat. Comm. 1, 39 (2010)]. Moreover, the technique also allows to perform local spectroscopy of electron transport through selected localized states [F. Martins et al., New J. of Phys. 15, 013049 (2013); F. Martins et al., Sci. Rep. 3, 1416 (2013)]. Overall, these examples show that scanning gate microscopy is a powerful tool for imaging charge carrier behavior inside devices fabricated from a variety of materials, and opens the way towards a more intimate manipulation of charge and quasiparticle transport. This work was performed in collaboration with F. Martins, S. Faniel, B. Brun, M. Pala, X. Wallart, L. Desplanque, B. Rosenow, T. Ouisse, H. Sellier, S. Huant and V. Bayot.

  12. Screening of photocatalysts by scanning electrochemical microscopy.

    PubMed

    Lee, Joowook; Ye, Heechang; Pan, Shanlin; Bard, Allen J

    2008-10-01

    A method for rapid screening of photocatalysts employing a form of scanning electrochemical microscopy (SECM) is described. A piezoelectric dispenser was used to deposit arrays composed of approximately 300-microm-size photocatalyst spots with different compositions onto conducting glass, fluorine-doped tin oxide substrate. The scanning tip of the SECM was replaced by a fiber optic connected to a xenon lamp and was rapidly scanned over the array. In this arrangement, the photocatalytic performance of the spots was evaluated by measuring the photocurrent at the substrate of the array. A fiber optic with a ring electrode can also be used to electrochemically detect products of the photoreaction. Several iron oxide-based bimetallic oxide combinations were found to exhibit enhanced photocatalytic activity, when compared to pure alpha-Fe2O3. These combinations included iron-palladium, iron-europium, and iron-rubidium in specific ratios. A trimetallic bismuth-vanadium-zinc oxide combination was also found to show a higher photocurrent, by approximately 40%, compared to BiVO3.

  13. Correlative photoactivated localization and scanning electron microscopy.

    PubMed

    Kopek, Benjamin G; Shtengel, Gleb; Grimm, Jonathan B; Clayton, David A; Hess, Harald F

    2013-01-01

    The ability to localize proteins precisely within subcellular space is crucial to understanding the functioning of biological systems. Recently, we described a protocol that correlates a precise map of fluorescent fusion proteins localized using three-dimensional super-resolution optical microscopy with the fine ultrastructural context of three-dimensional electron micrographs. While it achieved the difficult simultaneous objectives of high photoactivated fluorophore preservation and ultrastructure preservation, it required a super-resolution optical and specialized electron microscope that is not available to many researchers. We present here a faster and more practical protocol with the advantage of a simpler two-dimensional optical (Photoactivated Localization Microscopy (PALM)) and scanning electron microscope (SEM) system that retains the often mutually exclusive attributes of fluorophore preservation and ultrastructure preservation. As before, cryosections were prepared using the Tokuyasu protocol, but the staining protocol was modified to be amenable for use in a standard SEM without the need for focused ion beam ablation. We show the versatility of this technique by labeling different cellular compartments and structures including mitochondrial nucleoids, peroxisomes, and the nuclear lamina. We also demonstrate simultaneous two-color PALM imaging with correlated electron micrographs. Lastly, this technique can be used with small-molecule dyes as demonstrated with actin labeling using phalloidin conjugated to a caged dye. By retaining the dense protein labeling expected for super-resolution microscopy combined with ultrastructural preservation, simplifying the tools required for correlative microscopy, and expanding the number of useful labels we expect this method to be accessible and valuable to a wide variety of researchers.

  14. Angular Approach Scanning Ion Conductance Microscopy.

    PubMed

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

    2016-05-24

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

  15. Scanning Tunneling Microscopy Observation of Phonon Condensate

    DOE PAGES

    Altfeder, Igor; Balatsky, Alexander V.; Voevodin, Andrey A.; ...

    2017-02-22

    Using quantum tunneling of electrons into vibrating surface atoms, phonon oscillations can be observed on the atomic scale. Phonon interference patterns with unusually large signal amplitudes have been revealed by scanning tunneling microscopy in intercalated van der Waals heterostructures. Our results show that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance. The observed coherence of these quasi-bound states most likely arises from phase- and frequency-synchronized dynamics of all phonon modes, and indicates the formationmore » of many-body condensate of optical phonons around resonant defects. We found that increasing the strength of the scattering resonance causes the increase of the condensate droplet radius without affecting the condensate fraction inside it. The condensate can be observed at room temperature.« less

  16. Scanning Tunneling Microscopy Observation of Phonon Condensate

    PubMed Central

    Altfeder, Igor; Voevodin, Andrey A.; Check, Michael H.; Eichfeld, Sarah M.; Robinson, Joshua A.; Balatsky, Alexander V.

    2017-01-01

    Using quantum tunneling of electrons into vibrating surface atoms, phonon oscillations can be observed on the atomic scale. Phonon interference patterns with unusually large signal amplitudes have been revealed by scanning tunneling microscopy in intercalated van der Waals heterostructures. Our results show that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance. The observed coherence of these quasi-bound states most likely arises from phase- and frequency-synchronized dynamics of all phonon modes, and indicates the formation of many-body condensate of optical phonons around resonant defects. We found that increasing the strength of the scattering resonance causes the increase of the condensate droplet radius without affecting the condensate fraction inside it. The condensate can be observed at room temperature. PMID:28225066

  17. Scanning Tunneling Microscopy Observation of Phonon Condensate.

    PubMed

    Altfeder, Igor; Voevodin, Andrey A; Check, Michael H; Eichfeld, Sarah M; Robinson, Joshua A; Balatsky, Alexander V

    2017-02-22

    Using quantum tunneling of electrons into vibrating surface atoms, phonon oscillations can be observed on the atomic scale. Phonon interference patterns with unusually large signal amplitudes have been revealed by scanning tunneling microscopy in intercalated van der Waals heterostructures. Our results show that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance. The observed coherence of these quasi-bound states most likely arises from phase- and frequency-synchronized dynamics of all phonon modes, and indicates the formation of many-body condensate of optical phonons around resonant defects. We found that increasing the strength of the scattering resonance causes the increase of the condensate droplet radius without affecting the condensate fraction inside it. The condensate can be observed at room temperature.

  18. Nonlinear femtosecond laser induced scanning tunneling microscopy.

    PubMed

    Dey, Shirshendu; Mirell, Daniel; Perez, Alejandro Rodriguez; Lee, Joonhee; Apkarian, V Ara

    2013-04-21

    We demonstrate ultrafast laser driven nonlinear scanning tunneling microscopy (STM), under ambient conditions. The design is an adaptation of the recently introduced cross-polarized double beat method, whereby z-polarized phase modulated fields are tightly focused at a tunneling junction consisting of a sharp tungsten tip and an optically transparent gold film as substrate. We demonstrate the prerequisites for ultrafast time-resolved STM through an operative mechanism of nonlinear laser field-driven tunneling. The spatial resolution of the nonlinear laser driven STM is determined by the local field intensity. Resolution of 0.3 nm-10 nm is demonstrated for the intensity dependent, exponential tunneling range. The demonstration is carried out on a junction consisting of tungsten tip and gold substrate. Nano-structured gold is used for imaging purposes, to highlight junction plasmon controlled tunneling in the conductivity limit.

  19. Scanning microscopy in microcircuit failure analysis

    NASA Technical Reports Server (NTRS)

    Nicolas, D. P.

    1978-01-01

    A three-phase microcircuit failure analysis procedure is presented. In the first phase, the device is nondestructively tested and the data obtained is correlated with the circumstances surrounding the failure event. The device is then subjected to a limited nondestructive analysis dominated by optical and scanning electron microscopy (SEM). Knowing that microcircuits usually fail from manufacturing defects or misuse, the analyst looks for one of the probable mechanisms. The SEM has two special operating modes that provide unique data for nondestructive analysis: voltage contrast and conductive current. These are used with other SEM modes and surface analysis techniques to analyze complicated microcircuits. The last phase includes the destructive procedures. The end product of these analyses is a corrective action that will yield a highly reliable system.

  20. Electric fields in Scanning Electron Microscopy simulations

    NASA Astrophysics Data System (ADS)

    Arat, K. T.; Bolten, J.; Klimpel, T.; Unal, N.

    2016-03-01

    The electric field distribution and charging effects in Scanning Electron Microscopy (SEM) were studied by extending a Monte-Carlo based SEM simulator by a fast and accurate multigrid (MG) based 3D electric field solver. The main focus is on enabling short simulation times with maintaining sufficient accuracy, so that SEM simulation can be used in practical applications. The implementation demonstrates a gain in computation speed, when compared to a Gauss-Seidel based reference solver is roughly factor of 40, with negligible differences in the result (~10-6 𝑉). In addition, the simulations were compared with experimental SEM measurements using also complex 3D sample, showing that i) the modelling of e-fields improves the simulation accuracy, and ii) multigrid method provide a significant benefit in terms of simulation time.

  1. Scanning electron microscopy of tinea nigra.

    PubMed

    Guarenti, Isabelle Maffei; Almeida, Hiram Larangeira de; Leitão, Aline Hatzenberger; Rocha, Nara Moreira; Silva, Ricardo Marques E

    2014-01-01

    Tinea nigra is a rare superficial mycosis caused by Hortaea werneckii. This infection presents as asymptomatic brown to black maculae mostly in palmo-plantar regions. We performed scanning electron microscopy of a superficial shaving of a tinea nigra lesion. The examination of the outer surface of the sample showed the epidermis with corneocytes and hyphae and elimination of fungal filaments. The inner surface of the sample showed important aggregation of hyphae among keratinocytes, which formed small fungal colonies. The ultrastructural findings correlated with those of dermoscopic examination - the small fungal aggregations may be the dark spicules seen on dermoscopy - and also allowed to document the mode of dissemination of tinea nigra, showing how hyphae are eliminated on the surface of the lesion.

  2. Scanning Tunneling Microscopy Observation of Phonon Condensate

    NASA Astrophysics Data System (ADS)

    Altfeder, Igor; Voevodin, Andrey A.; Check, Michael H.; Eichfeld, Sarah M.; Robinson, Joshua A.; Balatsky, Alexander V.

    2017-02-01

    Using quantum tunneling of electrons into vibrating surface atoms, phonon oscillations can be observed on the atomic scale. Phonon interference patterns with unusually large signal amplitudes have been revealed by scanning tunneling microscopy in intercalated van der Waals heterostructures. Our results show that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance. The observed coherence of these quasi-bound states most likely arises from phase- and frequency-synchronized dynamics of all phonon modes, and indicates the formation of many-body condensate of optical phonons around resonant defects. We found that increasing the strength of the scattering resonance causes the increase of the condensate droplet radius without affecting the condensate fraction inside it. The condensate can be observed at room temperature.

  3. Scanning electron microscopy of molluscum contagiosum*

    PubMed Central

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

    2013-01-01

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

  4. Hexamethyldisilazane for scanning electron microscopy of Gastrotricha.

    PubMed

    Hochberg, R; Litvaitis, M K

    2000-01-01

    We evaluated treatment with hexamethyldisilazane (HMDS) as an alternative to critical-point drying (CPD) for preparing microscopic Gastrotricha for scanning electron microscopy (SEM). We prepared large marine (2 mm) and small freshwater (100 microm) gastrotrichs using HMDS as the primary dehydration solvent and compared the results to earlier investigations using CPD. The results of HMDS dehydration are similar to or better than CPD for resolution of two important taxonomic features: cuticular ornamentation and patterns of ciliation. The body wall of both sculpted (Lepidodermella) and smooth (Dolichodasys) gastrotrichs retained excellent morphology as did the delicate sensory and locomotory cilia. The only unfavorable result of HMDS dehydration was an occasional coagulation of gold residue when the solvent had not fully evaporated before sputter-coating. We consider HMDS an effective alternative for preparing of gastrotrichs for SEM because it saves time and expense compared to CPD.

  5. Scanning tunneling microscopy of polysialic acid

    NASA Astrophysics Data System (ADS)

    Haikkila, L.; Aalto, J. P. S.; Pelliniemi, L. J.; Laiho, R.; Finne, J.

    Polysialic Acid (PSA) fragments consisting of 13 and 17 residues were transferred to aqueous solution and applied as droplets on freshly cleft pyrolytic graphite for Scanning Tunneling Microscopy (STM) investigations. Structures of carbohydrates are generally difficult to investigate in detail. In experiments the conductivity and stability of PSA on a graphite substrate was found to be sufficient for stable operation of STM. The results reveal hillocks and their tendency to form prolonged arrangements on the substrate. The dimensions of subunits of these structures correspond to those of single particles (length about 3 mm) occasionally observed on the otherwise atomically flat surface of graphite. These results give further evidence for usefulness of STM in investigations of structures formed by macromolecules.

  6. 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.

  7. 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.

  8. 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.

  9. Spatial Resolution in Scanning Electron Microscopy and Scanning Transmission Electron Microscopy Without a Specimen Vacuum Chamber

    SciTech Connect

    Nguyen, Kayla X.; Holtz, Megan E.; Richmond-Decker, Justin; Muller, David A.

    2016-07-25

    Abstract

    A long-standing goal of electron microscopy has been the high-resolution characterization of specimens in their native environment. However, electron optics require high vacuum to maintain an unscattered and focused probe, a challenge for specimens requiring atmospheric or liquid environments. Here, we use an electron-transparent window at the base of a scanning electron microscope’s objective lens to separate column vacuum from the specimen, enabling imaging under ambient conditions, without a specimen vacuum chamber. We demonstrate in-air imaging of specimens at nanoscale resolution using backscattered scanning electron microscopy (airSEM) and scanning transmission electron microscopy. We explore resolution and contrast using Monte Carlo simulations and analytical models. We find that nanometer-scale resolution can be obtained at gas path lengths up to 400μm, although contrast drops with increasing gas path length. As the electron-transparent window scatters considerably more than gas at our operating conditions, we observe that the densities and thicknesses of the electron-transparent window are the dominant limiting factors for image contrast at lower operating voltages. By enabling a variety of detector configurations, the airSEM is applicable to a wide range of environmental experiments including the imaging of hydrated biological specimens andin situchemical and electrochemical processes.

  10. Spatial Resolution in Scanning Electron Microscopy and Scanning Transmission Electron Microscopy Without a Specimen Vacuum Chamber.

    PubMed

    Nguyen, Kayla X; Holtz, Megan E; Richmond-Decker, Justin; Muller, David A

    2016-08-01

    A long-standing goal of electron microscopy has been the high-resolution characterization of specimens in their native environment. However, electron optics require high vacuum to maintain an unscattered and focused probe, a challenge for specimens requiring atmospheric or liquid environments. Here, we use an electron-transparent window at the base of a scanning electron microscope's objective lens to separate column vacuum from the specimen, enabling imaging under ambient conditions, without a specimen vacuum chamber. We demonstrate in-air imaging of specimens at nanoscale resolution using backscattered scanning electron microscopy (airSEM) and scanning transmission electron microscopy. We explore resolution and contrast using Monte Carlo simulations and analytical models. We find that nanometer-scale resolution can be obtained at gas path lengths up to 400 μm, although contrast drops with increasing gas path length. As the electron-transparent window scatters considerably more than gas at our operating conditions, we observe that the densities and thicknesses of the electron-transparent window are the dominant limiting factors for image contrast at lower operating voltages. By enabling a variety of detector configurations, the airSEM is applicable to a wide range of environmental experiments including the imaging of hydrated biological specimens and in situ chemical and electrochemical processes.

  11. Quantum well resonances in scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Hörmandinger, G.; Pendry, J. B.

    1993-09-01

    Thin metallic overlayers on a substrate from quantum wells perpendicular to the surface. They can give rise to resonant states, which are observable e.g. by photoemission and LEED. Recent experimental results [J.A. Kubby and W.J. Greene, Phys. Rev. Lett. 68 (1992) 329] indicate that they can also be observed in scanning tunneling microscopy, which extends the range of this extremely surface-sensitive device into the interior of the sample, and makes it possible to image features of a buried interface with the STM. We present the results of model calculations for Ni/Cu(100) and Pd/Ag(100). The variations in the tip height caused by the resonances are of order 0.1 Å, which agrees well with the observations. We find that quantum well resonances may be observable if they occur at or above the Fermi energy of the sample, in a band perpendicular to the surface. The lateral resolution of buried steps is estimated using a junction of two free-electron quantum wells. It is found to vary slowly as a function of the overlayer thickness. For a metallic layer 5 Å thick, we obtain a resolution in the order of 5 Å.

  12. Catalysis resolved using scanning tunnelling microscopy.

    PubMed

    Bowker, Michael

    2007-10-01

    The technique of scanning tunnelling microscopy has revolutionised our understanding of surface chemistry, due to its ability to image at the atomic and molecular scale, the very realm at which chemistry operates. This critical review focuses on its contribution to the resolution of various problems in heterogeneous catalysis, including surface structure, surface intermediates, active sites and spillover. In the article a number of images of surfaces are shown, many at atomic resolution, and the insights which these give into surface reactivity are invaluable. The article should be of interest to catalytic chemists, surface and materials scientists and those involved with nanotechnology/nanoscience. (129 references.)The graphical abstract shows the reaction between gas phase methanol and oxygen islands on Cu(110), courtesy of Philip Davies of Cardiff University. The added-row island is shown as silver-coloured spheres (copper) and red (oxygen) on the copper surface. Methanol preferentially reacts with the terminal oxygen atoms in the island forming adsorbed methoxy and OH groups. Only the terminal oxygen atoms in the island are active sites for the reaction.

  13. [Scanning electron microscopy of Paragonimus proliferus].

    PubMed

    Zhou, Ben-jiang

    2005-10-30

    To identify the species of Paragonimus proliferus with scanning electron microscopy (SEM) based on the surface structure of excysted metacercariae, adult worms and eggs. Crabs were collected from the endemic area of P. proliferus and excysted metacercariae were separated. Adult worms at different ages and eggs were obtained from the experimentally infected rats. After being fixed by 2.5% glutardialdehyde and 1% osmic acid, alcohol dehydration, gilded by ion spatter, the specimens were observed under SEM by STEREOSCAN-100. The cuticular spines of excysted metacercariae distributed in single pattern, bayonet-shaped or scale-shaped. There were 6 dome-shape papillae around the rim of the ventral sucker symmetrically arranged. The cuticular spines of different age adult worms distributed in group pattern, relatively denser and more regularly arranged in the anterior part than the posterior part of the worm body. The shape and arrangement of the cuticular spines on adult worms at different ages were basically uniform. The surface of eggshell including the operculum was generally smooth. The shell rim joining the operculum was thick and prominent. A knot-like prominence was observed at the aboperculum end. The cuticular spines of both excysted metacercariae and adult worms of P. proliferus show its own characteristics, but the size and shape of the cuticular spines among individuals or different parts of the same specimen show certain differences.

  14. Complete information acquisition in scanning probe microscopy

    SciTech Connect

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

    2015-03-13

    In the last three decades, scanning probe microscopy (SPM) has emerged as a primary tool for exploring and controlling the nanoworld. A critical part of the SPM measurements is the information transfer from the tip-surface junction to a macroscopic measurement system. This process reduces the many degrees of freedom of a vibrating cantilever to relatively few parameters recorded as images. Similarly, the details of dynamic cantilever response at sub-microsecond time scales of transients, higher-order eigenmodes and harmonics are averaged out by transitioning to millisecond time scale of pixel acquisition. Hence, the amount of information available to the external observer is severely limited, and its selection is biased by the chosen data processing method. Here, we report a fundamentally new approach for SPM imaging based on information theory-type analysis of the data stream from the detector. This approach allows full exploration of complex tip-surface interactions, spatial mapping of multidimensional variability of material s properties and their mutual interactions, and SPM imaging at the information channel capacity limit.

  15. Scanning tunneling microscopy of sulfide surfaces

    SciTech Connect

    Eggleston, C.M.; Hochella, M.F. Jr. )

    1990-05-01

    A fundamental understanding of reactions that occur at mineral surfaces, many of which have bearing on important environmental issues, requires knowledge of atomic surface structures. Scanning tunneling microscopy (STM) is a new technique which can be used to image atomic surface structures in real space. We briefly review STM theory and interpret STM images of galena (PbS) and pyrite (FeS{sub 2}) surfaces by comparing the bias-voltage dependence of the images to the electronic structures of the materials. This approach amounts to a form of tunneling spectroscopy which may ultimately be used to identify individual atoms on mineral surfaces. STM imaging was accomplished on fresh fracture surfaces as well as on surfaces that had been exposed to air for long periods of time. For galena, the Pb and S sites are distinguishable, and the S sites appear to be imaged preferentially. A galena surface which had been oxidized in air for several months was imaged, suggesting either that oxidation products are very thin, occur in local patches on the surface, or are both non-conductive and not coherently bound to the galena surface. Iron appears to be imaged preferentially on fresh fracture surfaces of pyrite. Atomic positions on a pyrite growth surface were not those expected for a termination of the bulk pyrite structure; it is likely that a surface oxidation product was imaged.

  16. Scanning electron microscopy of softened enamel.

    PubMed

    Eisenburger, M; Shellis, R P; Addy, M

    2004-01-01

    After exposing enamel specimens to 0.3% citric acid at pH 3.2 for various times, the acid was titrated to pH 7 before rinsing the specimens in water. After freeze-drying the specimens were examined by scanning electron microscopy. This procedure eliminates artefacts due to drying and mineral precipitation. The results showed that the outer region of softened enamel is much more delicate than previously thought, even after short (5- to 20-min) etching times. Mineral was lost from both prism boundaries and the prism bodies, resulting in a surface presenting thin, separate crystal bundles. In further studies, replicas of subsurface pores, created by resin impregnation, showed the softening depth to be several times greater than is suggested by techniques based on removing the softened enamel by physical forces. The results point to a need for improved methods of measuring softening depth. More importantly, it appears that the outer region of the softened layer remaining after an erosive challenge might be too fragile to resist frictional forces in vivo. Copyright 2004 S. Karger AG, Basel

  17. Complete information acquisition in scanning probe microscopy

    DOE PAGES

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

    2015-03-13

    In the last three decades, scanning probe microscopy (SPM) has emerged as a primary tool for exploring and controlling the nanoworld. A critical part of the SPM measurements is the information transfer from the tip-surface junction to a macroscopic measurement system. This process reduces the many degrees of freedom of a vibrating cantilever to relatively few parameters recorded as images. Similarly, the details of dynamic cantilever response at sub-microsecond time scales of transients, higher-order eigenmodes and harmonics are averaged out by transitioning to millisecond time scale of pixel acquisition. Hence, the amount of information available to the external observer ismore » severely limited, and its selection is biased by the chosen data processing method. Here, we report a fundamentally new approach for SPM imaging based on information theory-type analysis of the data stream from the detector. This approach allows full exploration of complex tip-surface interactions, spatial mapping of multidimensional variability of material s properties and their mutual interactions, and SPM imaging at the information channel capacity limit.« less

  18. Scanned probe microscopy for thin film superconductor development

    SciTech Connect

    Moreland, J.

    1996-12-31

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

  19. 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

  20. Application of scanning acoustic microscopy to advanced structural ceramics

    NASA Technical Reports Server (NTRS)

    Vary, Alex; Klima, Stanley J.

    1987-01-01

    A review is presentod of research investigations of several acoustic microscopy techniques for application to structural ceramics for advanced heat engines. Results obtained with scanning acoustic microscopy (SAM), scanning laser acoustic microscopy (SLAM), scanning electron acoustic microscopy (SEAM), and photoacoustic microscopy (PAM) are compared. The techniques were evaluated on research samples of green and sintered monolithic silicon nitrides and silicon carbides in the form of modulus-of-rupture bars containing deliberately introduced flaws. Strengths and limitations of the techniques are described with emphasis on statistics of detectability of flaws that constitute potential fracture origins.

  1. Electrostatic Surface Characterization by Scanning Probe Microscopy.

    NASA Astrophysics Data System (ADS)

    Leng, Yaojian

    1995-01-01

    The electrostatic properties of surfaces are important in biological, polymer and semiconductor physics. Several newly developed scanning probe microscopies can provide nanometer scale characterization of these surfaces. In the course of this work, an Electrostatic Force Microscope (EFM) and a Kelvin Probe Force Microscope (KPFM) have been built using interferometric force detection. An EFM is a modified noncontact mode Atomic Force Microscope, capable of simultaneously measuring surface topography, surface charge or surface potential, and capacitance. A KPFM is similar to the classical Kelvin method in measuring surface potential, only in this case, forces are detected instead of currents. A 10^{-4} A/surdHz displacement detection sensitivity has been achieved. A 200 A spatial resolution and a sub-mV electrostatic potential sensitivity have been demonstrated. The capability of the EFM to map charge and dielectric variations on biological and polymeric surfaces has been demonstrated. Studies have been made on red blood cells, modified Teflon FEP films, and contact lens materials. A quantitative method to measure surface charge density on a nanometer scale has been established. The redistribution of mobile surface ions has been visualized for the first time by the EFM on a submicron scale. It has been shown that the drift in the saturation current observed on the open gate field effect transistor is due to the migration of mobile surface ions under lateral fields. Atomic ordering in GaInP, controlled either by growth temperature or by substrate misorientation, has been studied by the KPFM both in cross section and on the growth plane. It is shown that KPFM is capable of distinguishing ordered GaInP from disordered GaInP. The contrast is observed to depend on the applied ac amplitude used in the measurement. The experiments indicate that ordering in GaInP modifies the density and/or lifetime of the surface states.

  2. 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.

  3. Immobilization of DNA for scanning probe microscopy.

    PubMed Central

    Allison, D P; Bottomley, L A; Thundat, T; Brown, G M; Woychik, R P; Schrick, J J; Jacobson, K B; Warmack, R J

    1992-01-01

    Reproducible scanning tunneling microscope and atomic force microscope images of entire molecules of uncoated plasmid DNA chemically bound to surfaces are presented. The chemically mediated immobilization of DNA to surfaces and subsequent scanning tunneling microscope imaging of DNA molecules demonstrate that the problem of molecular instability to forces exerted by the probe tip, inherent with scanning probe microscopes, can be prevented. Images PMID:1438201

  4. [Environmental scanning electron microscopy for biofilm detection in tonsils].

    PubMed

    Ramírez-Camacho, Rafael; González-Tallón, Ana Isabel; Gómez, David; Trinidad, Almudena; Ibáñez, Andrés; García-Berrocal, José Ramón; Verdaguer, José María; González-García, José Angel; San Román, Julio

    2008-01-01

    To describe an environmental scanning electron microscopic method for the study of biofilms in clinical samples. A comparison with standard scanning electron microscopy is performed. Nine patients with a past history of recurrent tonsillitis underwent tonsillectomy. Samples from each patient were obtained for both conventional and environmental scanning electron microscopy. The tonsils removed from 2 patients with sleep apnoea syndrome were used as controls. Eight of nine tonsils had biofilms on their surface. Scanning electron microscopy showed accumulations of bacteria covered by fibrillar structures resulting from the sample dehydration process. Environmental scanning electron microscopy provided a view of bacteria embedded in a homogeneous, amorphous substance that was preserved during the examination. Environmental scanning electron microscopy permits the imaging of wet systems at different degrees of dehydration. It therefore allows researchers to observe biofilms in their natural hydrated state.

  5. A study of hydrogenated carbon fibers by scanning electron microscopy and confocal laser scanning microscopy.

    PubMed

    de la Cal, Antonio Madroñero; Aguado-Serrano, Juan; Rojas-Cervantes, Maria Luisa; Adame, Elena V Rosa; Marron, Belen Sarmiento; Rosende, Africa Castro; Nevshupa, Roman

    2009-06-01

    The hydrogen absorption process is studied in carbonaceous fibers produced from a mixture of methane and hydrogen. The absorption of the hydrogen was examined in two types of fibers, in "as-grown" state and after a process of desorption during an annealing to 1.473 K under vacuum. Later to its production process, the fibers withstand an oxidation in air to 973 K. The fibers were examined by means of scanning electron microscopy (SEM) and confocal microscopy by reflection. Differences in the behavior during the oxidation were observed between the fibers in as-grown state and those subjected to a further annealing. It could be verified that the fibers were really constituted by two different phases. In one of the phases, the storage of the hydrogen absorbed took place, whereas in the other phase there was no alteration. The process of annealing prior to the absorption of the hydrogen has an appreciable effect on the desorption rate of the hydrogen.

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

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2013-07-01

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

  7. Detection of a magnetic bead by hybrid nanodevices using scanning gate microscopy

    NASA Astrophysics Data System (ADS)

    Corte-León, H.; Krzysteczko, P.; Marchi, F.; Motte, J.-F.; Manzin, A.; Schumacher, H. W.; Antonov, V.; Kazakova, O.

    2016-05-01

    Hybrid ferromagnetic(Py)/non-magnetic metal(Au) junctions with a width of 400 nm are studied by magnetotransport measurements, magnetic scanning gate microscopy (SGM) with a magnetic bead (MB) attached to the probe, and micromagnetic simulations. In the transverse geometry, the devices demonstrate a characteristic magnetoresistive behavior that depends on the direction of the in plane magnetic field, with minimum/maximum variation when the field is applied parallel/perpendicular to the Py wire. The SGM is performed with a NdFeB bead of 1.6 μm diameter attached to the scanning probe. Our results demonstrate that the hybrid junction can be used to detect this type of MB. A rough approximation of the sensing volume of the junction has the shape of elliptical cylinder with the volume of ˜1.51 μm3. Micromagnetic simulations coupled to a magnetotransport model including anisotropic magnetoresistance and planar Hall effects are in good agreement with the experimental findings, enabling the interpretation of the SGM images.

  8. Scanning Auger microscopy study of W tips for scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Ottaviano, L.; Lozzi, L.; Santucci, S.

    2003-07-01

    Tungsten tips used in scanning tunneling microscopy (STM) (prepared via electrochemical etching with a 2 N KOH or NaOH solution) have been studied with state of the art scanning Auger microscopy (SAM) with chemical lateral resolution of 10 nm. The experiments were focused on the investigation of the W tips' apex shape and surface composition, for tips as etched, or after various postetching treatments performed for cleaning, sharpening, and surface oxide removal purposes. Ultrasonic cleaning likely bend the tip apex. Hydrofluoride etching successfully removes the native WO3 oxide layer, but this happens at the expense of the tip sharpness. Ion sputtering in ultrahigh vacuum is not always effective in sharpening and cleaning the tungsten tip apex, and we sometimes observed the formation of needle like nanotips, mostly composed of WO3. Direct resistive annealing of the tip (operated in the STM at 10 V, 50 nA set-point sample bias voltage and current, respectively) to remove the oxide layer, produces a coiling of the tip apex. In this case, atom transfer from the sample to the tip is directly demonstrated with Auger spectra taken at the tip apex.

  9. New form of scanning optical microscopy

    SciTech Connect

    Reddick, R.C.; Warmack, R.J.; Ferrell, T.L.

    1989-01-01

    The exponential decay of the evanescent field due to the total internal reflection (TIR) of a light beam in a prism is used to advantage in a new form of scanning optical microscope, the photon scanning tunneling microscope (PSTM). The PSTM is the photon analogue of the electron scanning tunneling microscope. The sample is placed on or forms the TIR surface and spatially modulates the evanescent field. Changes in intensity are monitored by a probe tip scanned over the surface, and the data are processed to generate an image of the sample. Subwavelength resolution in three dimensions is obtained because of the exponential nature of the evanescent field intensity. Images produced by a prototype instrument using 633-nm light and a 1-..mu..m probe tip are shown to have a lateral resolution of about 200 nm.

  10. The combination of scanning electron and scanning probe microscopy

    SciTech Connect

    Sapozhnikov, I. D.; Gorbenko, O. M. Felshtyn, M. L.; Golubok, A. O.

    2016-06-17

    We suggest the SPM module to combine SEM and SPM methods for studying surfaces. The module is based on the original mechanical moving and scanning system. The examples of studies of the steel surface microstructure in both SEM and SPM modes are presented.

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

    NASA Astrophysics Data System (ADS)

    Tong, Yongpeng; Li, Changming; Liang, Feng; Chen, Jianmin; Zhang, Hong; Liu, Guoqing; Sun, Huibin; Luong, John H. T.

    2008-12-01

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

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  14. 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.

  15. Scanning force microscopy under aqueous solutions.

    PubMed

    Bustamante, C; Rivetti, C; Keller, D J

    1997-10-01

    Merely ten years after its invention, the scanning force microscope is becoming a powerful method to investigate the structure and dynamics of biological molecules under aqueous environments. From the visualization of transcription in real time to the mechanical manipulation of individual proteins, the advances made during the past year open up a vast number of exciting applications of this technique in biology.

  16. Multi-channel scanning SQUID microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Su-Young

    I designed, fabricated, assembled, and tested an 8-channel high- Tc scanning SQUID system. I started by modifying an existing single-channel 77 K high-Tc scanning SQUID microscope into a multi-channel system with the goal of reducing the scanning time and improving the spatial resolution by increasing the signal-to-noise ratio S/N. I modified the window assembly, SQUID chip assembly, cold-finger, and vacuum connector. The main concerns for the multi-channel system design were to reduce interaction between channels, to optimize the use of the inside space of the dewar for more than 50 shielded wires, and to achieve good spatial resolution. In the completed system, I obtained the transfer function and the dynamic range (phimax ˜ 11phi0) for each SQUID. At 1kHz, the slew rate is about 3000 phi0/s. I also found that the white noise level varies from 5 muphi0/Hz1/2 to 20 muphi 0/Hz1/2 depending on the SQUID. A new data acquisition program was written that triggered on position and collects data from up to eight SQUIDS. To generate a single image from the multichannel system, I calibrated the tilt of the xy-stage and z-stage manually, rearranged the scanned data by cutting overlapping parts, and determined the applied field by multiplying by the mutual inductance matrix. I found that I could reduce scanning time and improve the image quality by doing so. In addition, I have analyzed and observed the effect of position noise on magnetic field images and used these results to find the position noise in my scanning SQUID microscope. My analysis reveals the relationship between spatial resolution and position noise and that my system was dominated by position noise under typical operating conditions. I found that the smaller the sensor-sample separation, the greater the effect of position noise is on the total effective magnetic field noise and on spatial resolution. By averaging several scans, I found that I could reduce position noise and that the spatial resolution can

  17. Resonance response of scanning force microscopy cantilevers

    SciTech Connect

    Chen, G.Y.; Warmack, R.J.; Thundat, T.; Allison, D.P. ); Huang, A. )

    1994-08-01

    A variational method is used to calculate the deflection and the fundamental and harmonic resonance frequencies of commercial V-shaped and rectangular atomic force microscopy cantilevers. The effective mass of V-shaped cantilevers is roughly half that calculated for the equivalent rectangular cantilevers. Damping by environmental gases, including air, nitrogen, argon, and helium, affects the frequency of maximum response and to a much greater degree the quality factor [ital Q]. Helium has the lowest viscosity, resulting in the highest [ital Q], and thus provides the best sensitivity in noncontact force microscopy. Damping in liquids is dominated by an increase in effective mass of the cantilever due to an added mass of the liquid being dragged with that cantilever.

  18. A New Twist on Scanning Thermal Microscopy

    DTIC Science & Technology

    2012-01-25

    Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, Ohio 45433, United States ‡School of Materials Science and Engineering...bimorphs do not suffer from these setbacks. In fact, thermal bimorphs transduced with an atomic force microscopy (AFM) quadrant photodetector have a...AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air Force Research Laboratory

  19. Local crystal structure analysis with 10-pm accuracy using scanning transmission electron microscopy.

    PubMed

    Saito, Mitsuhiro; Kimoto, Koji; Nagai, Takuro; Fukushima, Shun; Akahoshi, Daisuke; Kuwahara, Hideki; Matsui, Yoshio; Ishizuka, Kazuo

    2009-06-01

    We demonstrate local crystal structure analysis based on annular dark-field (ADF) imaging in scanning transmission electron microscopy (STEM). Using a stabilized STEM instrument and customized software, we first realize high accuracy of elemental discrimination and atom-position determination with a 10-pm-order accuracy, which can reveal major cation displacements associated with a variety of material properties, e.g. ferroelectricity and colossal magnetoresistivity. A-site ordered/disordered perovskite manganites Tb(0.5)Ba(0.5)MnO(3) are analysed; A-site ordering and a Mn-site displacement of 12 pm are detected in each specific atomic column. This method can be applied to practical and advanced materials, e.g. strongly correlated electron materials.

  20. Line-scan focal modulation microscopy

    NASA Astrophysics Data System (ADS)

    Pant, Shilpa; Li, Caixia; Gong, Zhiyuan; Chen, Nanguang

    2017-05-01

    We report the development of a line-scan focal modulation microscope (LSFMM) that is capable of high-speed image acquisition (>40 fps) with uncompromised optical sectioning capability. The improved background rejection and axial resolution of this imaging modality, enabled by focal modulation, are quantified with three-dimensional imaging data obtained from fluorescent beads. The signal-to-background ratio for the LSFMM system is one- to two-orders of magnitude higher than that for line-scanning confocal systems when imaging deep (up to 100 μm) into a turbid medium of optical properties similar to biological tissues. The imaging performance of LSFMM, in terms of both spatial and temporal resolutions, is further demonstrated with in vivo imaging experiments with live zebrafish larvae.

  1. Scanning probe microscopy of biomedical interfaces

    NASA Astrophysics Data System (ADS)

    Vansteenkiste, S. O.; Davies, M. C.; Roberts, C. J.; Tendler, S. J. B.; Williams, P. M.

    1998-02-01

    The development of the scanning probe microscopes over the past decade has provided a number of exciting new surface analytical techniques making a significant progress in the characterisation of biomedical interfaces. In this review, several examples are presented to illustrate that SPM is a powerful and promising tool for surface investigations including biomolecules, cell membranes, polymers and even living cells. The ability of the SPM instrument to monitor adhesion phenomena and provide quantitative information about intermolecular interactions is also described. Moreover, the huge potential of the scanning probe microscopes to study dynamic processes at interfaces under nearly physiological conditions is highlighted. Novel applications in the field of biochemistry, microbiology, biomaterial engineering, drug delivery and even medicine are discussed.

  2. CONFOCAL LASER SCANNING MICROSCOPY OF APOPTOSIS IN WHOLE MOUSE OVARIES

    EPA Science Inventory

    Confocal Laser Scanning Microscopy of Apoptosis in Whole Mouse Ovaries. Robert M. Zucker Susan C. Jeffay and Sally D. Perreault Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle...

  3. CONFOCAL LASER SCANNING MICROSCOPY OF APOPTOSIS IN WHOLE MOUSE OVARIES

    EPA Science Inventory

    Confocal Laser Scanning Microscopy of Apoptosis in Whole Mouse Ovaries. Robert M. Zucker Susan C. Jeffay and Sally D. Perreault Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle...

  4. Plant cell wall characterization using scanning probe microscopy techniques

    PubMed Central

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

    2009-01-01

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

  5. Full information acquisition in scanning probe microscopy and spectroscopy

    DOEpatents

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

    2017-04-04

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

  6. Scanning Transmission Electron Microscopy at High Resolution

    PubMed Central

    Wall, J.; Langmore, J.; Isaacson, M.; Crewe, A. V.

    1974-01-01

    We have shown that a scanning transmission electron microscope with a high brightness field emission source is capable of obtaining better than 3 Å resolution using 30 to 40 keV electrons. Elastic dark field images of single atoms of uranium and mercury are shown which demonstrate this fact as determined by a modified Rayleigh criterion. Point-to-point micrograph resolution between 2.5 and 3.0 Å is found in dark field images of micro-crystallites of uranium and thorium compounds. Furthermore, adequate contrast is available to observe single atoms as light as silver. Images PMID:4521050

  7. Atmospheric pressure scanning transmission electron microscopy.

    PubMed

    de Jonge, Niels; Bigelow, Wilbur C; Veith, Gabriel M

    2010-03-10

    Scanning transmission electron microscope (STEM) images of gold nanoparticles at atmospheric pressure have been recorded through a 0.36 mm thick mixture of CO, O2, and He. This was accomplished using a reaction cell consisting of two electron-transparent silicon nitride membranes. Gold nanoparticles of a full width at half-maximum diameter of 1.0 nm were visible above the background noise, and the achieved edge resolution was 0.4 nm in accordance with calculations of the beam broadening.

  8. Preparation of nematodes for scanning electron microscopy.

    PubMed

    Green, C D; Stone, A R; Turner, R H; Clark, S A

    1975-01-01

    Nematodes from the orders Tlyenchida and Rhabditida were fixed and processed in several different ways for examination with the scanning electron microscope (SEM). Four processes produced good preparations of fixed nematodes. Drying from acetone was the simplest of these techniques and most useful for regions of the tylenchid nematodes supported by skeletal tissue. Critical point drying, a more complicated procedure, gave good preparations, but they required special care in processing. Nematodes infiltrated with glycerol and a conducting agent were the most life-like but were difficult to examine. Specimens infiltrated with an epoxy resin looked natural and this was the most promising process tried.

  9. Energy gaps measured by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Giambattista, B.; Slough, C. G.; Coleman, R. V.; Subramanian, M. A.

    1990-11-01

    A scanning tunneling microscope (STM) has been used to measure energy gaps in the charge-density-wave (CDW) phases of the layer-structure dichalcogenides and in the high-temperature superconductor Bi2Sr2CaCu2O8. Measured values of ΔCDW at 4.2 K for 2H-TaSe2, 2H-TaS2, and 2H-NbSe2 are 80, 50, and 34 meV giving values of 2ΔCDW/kBTc equal to 15.2, 15.4, and 23.9, indicating strong coupling in these CDW systems. Measured values of ΔCDW at 4.2 K in 1T-TaSe2 and 1T-TaS2 are ~150 meV for both materials giving 2ΔCDW/kBTc~=5.8. STM scans of Bi2Sr2CaCu2O8 at 4.2 K resolve atoms on the BiOx layer and show possible variations in electronic structure. The energy gap determined from I versus V and dI/dV versus V curves is in the range 30-35 meV giving values of 2Δ/kBTc~=8. Spectroscopy measurements with the STM can exhibit large zero-bias anomalies which complicate the analysis of the energy-gap structure, but adequate separation has been accomplished.

  10. Scanning transmitted and reflected light microscopy: a novel microscopy for visualizing biomaterials at interfaces.

    PubMed

    Elkady, Ashraf S

    2007-01-01

    Two new types of light microscopy, scanning transmitted light and scanning reflected light microscopy (STLM and SRLM, respectively) were developed. STLM and SRLM are based on optical density recognition (ODR) of the scanned transmitted or reflected light, respectively, from the object to be visualized. The obtained image is a result of enhanced interference between the scanning and transmitted/reflected beams from the object. The new microscopy, in its initial phase, is ideally suited for monitoring macroscopic and sub-millimeter size self-assembly and for elucidating the connection between the macroscopic and nanoscopic worlds if combined with atomic force microscopy (AFM) or electron microscopy (EM). The method is demonstrated by monitoring the growth of 3D crystals from their original liquid phase. Some preliminary measurements carried out using the prototype of the new microscopy are presented and its current and future possible applications are described.

  11. Studies in Confocal Scanning Optical Microscopy

    NASA Astrophysics Data System (ADS)

    Corle, Timothy Richard

    Optical microscopes have been used as measurement tools in many areas of science of the past 300 years. Despite their maturity, there is still active research in the field. In particular the development of confocal scanning optical microscopes (CSOMs) in the 1970's has extended the usefulness of optical microscopes by giving them depth imaging capabilities. In a CSOM a defocused image disappears rather than blurring as it does with a standard microscope. The shallow depth of focus allows structures with a height difference smaller than one wavelength to be imaged independently, and thus quantitative measurements of height can be made. The design and construction of two CSOMs is discussed. The first is a mechanically scanned single pinhole microscope. This instrument was developed as a test bed on which to try out ideas relating to phase contrast imaging. The second is a Nipkow disk based real-time confocal scanning optical microscope (RSOM). These two microscopes were used to investigate the transverse and depth resolution of CSOMs. It is demonstrated that although they do not intrinsically have any better transverse resolution than a standard optical microscope, CSOMs produce a visually sharper image with increased contrast. The depth response of the CSOM is also investigated. A vector theory for the depth response is derived and compared with experimental results. It is shown that previously unexplained asymmetries in the sidelobe structure of this response can be accounted for by aberrations in the microscope objective. Phase contrast images can be generated by periodically defocusing the microscope, either mechanically or electro -optically and detecting a signal at the modulation frequency. A new electro-optic phase contrast microscope is described. The microscope is used to quantitatively measure both the height and width of thin film gratings. The depth response and point spread function of this microscope are also derived. It is shown that the sidelobe

  12. Scanning electron microscopy of bacteria Tetrasphaera duodecadis.

    PubMed

    Arroyo, E; Enríquez, L; Sánchez, A; Ovalle, M; Olivas, A

    2014-01-01

    This study reports the characterization of the Tetrasphaera duodecadis bacteria and the techniques used therein. In order to evaluate the morphological characteristics of the T. duodecadis bacteria scanning electron microscope (SEM) was used throughout its different growth stages. These microorganisms were grown in vitamin B12 broths with 1% tryptone, 0.2% yeast extract, and 0.1% glucose. The turbidimetric method was employed for the determination of bacterial concentration and growth curve. The SEM results show small agglomerates of 0.8 ± 0.05 µm during the lag phase, and rod-like shapes during the exponential phase with similar shapes in the stationary phase.

  13. Scanning He+ Ion Beam Microscopy and Metrology

    SciTech Connect

    Joy, David C.

    2011-11-10

    The CD-SEM has been the tool of choice for the imaging and metrology of semiconductor devices for the past three decades but now, with critical dimensions at the nanometer scale, electron beam instruments can no longer deliver adequate performance. A scanning microscope using a He+ ion beam offers superior resolution and depth of field, and provides enhanced imaging contrast. Device metrology performed using ion beam imaging produces data which is comparable to or better than that from a conventional CD-SEM although there are significant differences in the experimental conditions required and in the details of image formation. The charging generated by a He+ beam, and the sample damage that it can cause, require care in operation but are not major problems.

  14. Information Acquisition & Processing in Scanning Probe Microscopy

    SciTech Connect

    Kalinin, Sergei V; Jesse, Stephen; Proksch, Roger

    2008-01-01

    Much of the imaging and spectroscopy capabilities of the existing 20,000+ scanning probe microscopes worldwide relies on specialized data processing that links the microsecond (and sometimes faster) time scale of cantilever motion to the millisecond (and sometimes slower) time scale of image acquisition and feedback. In most SPMs, the cantilever is excited to oscillate sinusoidally and the time-averaged amplitude and/or phase are used as imaging or control signals. Traditionally, the step of converting the rapid motion of the cantilever into an amplitude or phase is performed by phase sensitive homodyne or phase-locked loop detection. The emergence of fast configurable data processing electronics in last several years has allowed the development of non-sinusoidal data acquisition and processing methods. Here, we briefly review the principles and limitations of phase sensitive detectors and discuss some of the emergent technologies based on rapid spectroscopic measurements in frequency- and time domains.

  15. Energy gaps measured by scanning tunneling microscopy

    SciTech Connect

    Wang, C.; Giambattista, B.; Slough, C.G.; Coleman, R.V. ); Subramanian, M.A. )

    1990-11-15

    A scanning tunneling microscope (STM) has been used to measure energy gaps in the charge-density-wave (CDW) phases of the layer-structure dichalcogenides and in the high-temperature superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}. Measured values of {Delta}{sub CDW} at 4.2 K for 2{ital H}-TaSe{sub 2}, 2{ital H}-TaS{sub 2}, and 2{ital H}-NbSe{sub 2} are 80, 50, and 34 meV giving values of 2{Delta}{sub CDW}/{ital k}{sub {ital B}T{ital c}} equal to 15.2, 15.4, and 23.9, indicating strong coupling in these CDW systems. Measured values of {Delta}{sub CDW} at 4.2 K in 1{ital T}-TaSe{sub 2} and 1{ital T}-TaS{sub 2} are {approximately}150 meV for both materials giving 2{Delta}{sub CDW}/{ital k}{sub {ital B}T{ital c}}{approx}5.8. STM scans of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} at 4.2 K resolve atoms on the BiO{sub {ital x}} layer and show possible variations in electronic structure. The energy gap determined from {ital I} versus {ital V} and {ital dI}/{ital dV} versus {ital V} curves is in the range 30--35 meV giving values of 2{Delta}/{ital k}{sub {ital B}T{ital c}}{approx}8. Spectroscopy measurements with the STM can exhibit large zero-bias anomalies which complicate the analysis of the energy-gap structure, but adequate separation has been accomplished.

  16. Scanning Electron and Phase-Contrast Microscopy of Bacterial Spores

    PubMed Central

    Bulla, L. A.; Julian, G. St.; Rhodes, R. A.; Hesseltine, C. W.

    1969-01-01

    The three-dimensional immages of free and intrasporangial spores produced by scanning electron microscopy show surface structures not visible by phase-contrast microscopy. Although fine surface detail is not elucidated by scanning electron microscopy, this technique does afford a definitive picture of the general shape of spores. Spores of Bacillus popilliae, B. lentimorbus, B. thuringiensis, B. alvei, B. cereus, and Sarcina ureae have varying patterns of surface ridge formation, whereas spores of B. larvae, B. subtilis, and B. licheniformis have relatively smooth surfaces. Images PMID:4907010

  17. 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.

  18. Forensic document analysis using scanning microscopy

    NASA Astrophysics Data System (ADS)

    Shaffer, Douglas K.

    2009-05-01

    The authentication and identification of the source of a printed document(s) can be important in forensic investigations involving a wide range of fraudulent materials, including counterfeit currency, travel and identity documents, business and personal checks, money orders, prescription labels, travelers checks, medical records, financial documents and threatening correspondence. The physical and chemical characterization of document materials - including paper, writing inks and printed media - is becoming increasingly relevant for law enforcement agencies, with the availability of a wide variety of sophisticated commercial printers and copiers which are capable of producing fraudulent documents of extremely high print quality, rendering these difficult to distinguish from genuine documents. This paper describes various applications and analytical methodologies using scanning electron miscoscopy/energy dispersive (x-ray) spectroscopy (SEM/EDS) and related technologies for the characterization of fraudulent documents, and illustrates how their morphological and chemical profiles can be compared to (1) authenticate and (2) link forensic documents with a common source(s) in their production history.

  19. Super-resolution scanning laser microscopy through virtually structured detection

    PubMed Central

    Lu, Rong-Wen; Wang, Ben-Quan; Zhang, Qiu-Xiang; Yao, Xin-Cheng

    2013-01-01

    High resolution microscopy is essential for advanced study of biological structures and accurate diagnosis of medical diseases. The spatial resolution of conventional microscopes is light diffraction limited. Structured illumination has been extensively explored to break the diffraction limit in wide field light microscopy. However, deployable application of the structured illumination in scanning laser microscopy is challenging due to the complexity of the illumination system and possible phase errors in sequential illumination patterns required for super-resolution reconstruction. We report here a super-resolution scanning laser imaging system which employs virtually structured detection (VSD) to break the diffraction limit. Without the complexity of structured illumination, VSD provides an easy, low-cost and phase-artifact free strategy to achieve super-resolution in scanning laser microscopy. PMID:24049688

  20. Evaluation of magnetic flux distribution from magnetic domains in [Co/Pd] nanowires by magnetic domain scope method using contact-scanning of tunneling magnetoresistive sensor

    SciTech Connect

    Okuda, Mitsunobu Miyamoto, Yasuyoshi; Miyashita, Eiichi; Hayashi, Naoto

    2014-05-07

    Current-driven magnetic domain wall motions in magnetic nanowires have attracted great interests for physical studies and engineering applications. The magnetic force microscope (MFM) is widely used for indirect verification of domain locations in nanowires, where relative magnetic force between the local domains and the MFM probe is used for detection. However, there is an occasional problem that the magnetic moments of MFM probe influenced and/or rotated the magnetic states in the low-moment nanowires. To solve this issue, the “magnetic domain scope for wide area with nano-order resolution (nano-MDS)” method has been proposed recently that could detect the magnetic flux distribution from the specimen directly by scanning of tunneling magnetoresistive field sensor. In this study, magnetic domain structure in nanowires was investigated by both MFM and nano-MDS, and the leakage magnetic flux density from the nanowires was measured quantitatively by nano-MDS. Specimen nanowires consisted from [Co (0.3)/Pd (1.2)]{sub 21}/Ru(3) films (units in nm) with perpendicular magnetic anisotropy were fabricated onto Si substrates by dual ion beam sputtering and e-beam lithography. The length and the width of the fabricated nanowires are 20 μm and 150 nm. We have succeeded to obtain not only the remanent domain images with the detection of up and down magnetizations as similar as those by MFM but also magnetic flux density distribution from nanowires directly by nano-MDS. The obtained value of maximum leakage magnetic flux by nano-MDS is in good agreement with that of coercivity by magneto-optical Kerr effect microscopy. By changing the protective diamond-like-carbon film thickness on tunneling magnetoresistive sensor, the three-dimensional spatial distribution of leakage magnetic flux could be evaluated.

  1. Open Source Scanning Probe Microscopy Control Software Package Gxsm

    SciTech Connect

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

    2009-08-10

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

  2. Open Source Scanning Probe Microscopy Control Software package GXSM

    SciTech Connect

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

    2010-05-01

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

  3. Vector sensor for scanning SQUID microscopy

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

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

  4. Diagnostic applications of scanning electron microscopy and microanalysis in pathology.

    PubMed

    Abraham, J L

    1979-08-01

    Microanalytical technology developed within the last decade provides important information in diagnostic pathology. Scanning electron microscopy, including backscattered electron imaging and energy dispersive X-ray analysis should become at least as valuable as polarized light microscopy, histochemistry and conventional transmission electron microscopy. Other as yet less available techniques such as the ion microprobe and laser Raman microprobe are also valuable. The pathologist should consider the use of microanalytic techniques in any disease process in which endogenous or exogenous materials may be present in the tissues, in the same manner in which one would perform stains for microorganisms. Cases are presented illustrating the tissue preparation and results of scanning electron microscopy and energy dispersive X-ray analysis in diagnosis.

  5. System and method for compressive scanning electron microscopy

    DOEpatents

    Reed, Bryan W

    2015-01-13

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

  6. Super-Resolution Laser Scanning Microscopy through Spatiotemporal Modulation

    PubMed Central

    Lu, Ju; Min, Wei; Conchello, José-Angel; Xie, Xiaoliang Sunney; Lichtman, Jeff W.

    2009-01-01

    Super-resolution optical microscopy has attracted great interest among researchers in many fields, especially in biology where the scale of physical structures and molecular processes fall below the diffraction limit of resolution for light. As one of the emerging techniques, structured illumination microscopy can double the resolution by shifting unresolvable spatial frequencies into the pass-band of the microscope through spatial frequency mixing with a wide-field structured illumination pattern. However, such a wide-field scheme typically can only image optically thin samples and is incompatible with multiphoton processes such as two-photon fluorescence, which require point scanning with a focused laser beam. Here, we propose two new super-resolution schemes for laser scanning microscopy by generalizing the concept of a spatially nonuniform imaging system. One scheme, scanning patterned illumination (SPIN) microscopy, employs modulation of the excitation combined with temporally cumulative imaging by a nondescanned array detector. The other scheme, scanning patterned detection (SPADE) microscopy, utilizes detection modulation together with spatially cumulative imaging, in this case by a nondescanned single-element detector. When combined with multiphoton excitation, both schemes can image thick samples with three-dimensional optical sectioning and much improved resolution. PMID:19743870

  7. Tunnel magnetoresistance scan of a pristine three-dimensional topological insulator

    NASA Astrophysics Data System (ADS)

    Roy, Sthitadhi; Soori, Abhiram; Das, Sourin

    2015-01-01

    Though the Fermi surface of surface states of a 3D topological insulator (TI) has zero magnetization, an arbitrary segment of the full Fermi surface has a unique magnetic moment consistent with the type of spin-momentum locking in hand. We propose a three-terminal set up, which directly couples to the magnetization of a chosen segment of a Fermi surface hence leading to a finite tunnel magnetoresistance (TMR) response of the nonmagnetic TI surface states, when coupled to spin polarized STM probe. This multiterminal TMR not only provides a unique signature of spin-momentum locking for a pristine TI but also provides a direct measure of momentum resolved out of plane polarization of hexagonally warped Fermi surfaces relevant for Bi2Te3 , which could be as comprehensive as spin-resolved ARPES. Implication of this unconventional TMR is also discussed in the broader context of 2D spin-orbit (SO) materials.

  8. Three-dimensional arbitrary trajectory scanning photoacoustic microscopy

    PubMed Central

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

    2014-01-01

    We have enhanced photoacoustic microscopy with three-dimensional arbitrary trajectory (3-DAT) scanning, which can rapidly image selected vessels over a large field of view (FOV) and maintain a high signal-to-noise ratio (SNR) despite the depth variation of the vessels. We showed that hemoglobin oxygen saturation (sO2) and blood flow can be measured simultaneously in a mouse ear in vivo at a frame rate 67 times greater than that of a traditional two-dimensional raster scan. We also observed sO2 dynamics in response to switching from systemic hypoxia to hyperoxia. 3-DAT-scanning photoacoustic microscopy. Schematic diagram of the 3D scanning stage and method. PMID:25077689

  9. Standardless atom counting in scanning transmission electron microscopy.

    PubMed

    LeBeau, James M; Findlay, Scott D; Allen, Leslie J; Stemmer, Susanne

    2010-11-10

    We demonstrate that high-angle annular dark-field imaging in scanning transmission electron microscopy allows for quantification of the number and location of all atoms in a three-dimensional, crystalline, arbitrarily shaped specimen without the need for a calibration standard. We show that the method also provides for an approach to directly measure the finite effective source size of a scanning transmission electron microscope.

  10. Cryo-scanning electron microscopy and light microscopy for the study of fungi interactions.

    PubMed

    Sempere, F; Santamarina, M P

    2011-03-01

    The application of the cryo-scanning electron microscopy and light microscopy for the study of the interactions at different environmental conditions between Penicillium oxalicum and Fusarium verticillioides is described. A dual microculture was developed for the light microscopy analysis of the interaction. The microscope and macroscopic examinations were compared. Analysis of Petri plates revealed that F. verticillioides was a competitor for space and nutrients while P. oxalicum was a mycoparasite under the microscopic observations.

  11. Laser-scanning Doppler photoacoustic microscopy based on temporal correlation

    NASA Astrophysics Data System (ADS)

    Song, Wei; Liu, Wenzhong; Zhang, Hao F.

    2013-05-01

    We present a methodology to measure absolute flow velocity using laser-scanning photoacoustic microscopy. To obtain the Doppler angle, the angle between ultrasonic detection axis and flow direction, we extracted the distances between the transducer and three adjacent scanning points along the flow and repeatedly applied the law of cosines. To measure flow velocity along the ultrasonic detection axis, we calculated the time shift between two consecutive photoacoustic waves at the same scanning point, then converted the time shift to velocity according to the sound velocity and time interval between two laser illuminations. We verified our method by imaging flow phantoms.

  12. A dynamic scanning method based on signal-statistics for scanning electron microscopy.

    PubMed

    Timischl, F

    2014-01-01

    A novel dynamic scanning method for noise reduction in scanning electron microscopy and related applications is presented. The scanning method dynamically adjusts the scanning speed of the electron beam depending on the statistical behavior of the detector signal and gives SEM images with uniform and predefined standard deviation, independent of the signal value itself. In the case of partially saturated images, the proposed method decreases image acquisition time without sacrificing image quality. The effectiveness of the proposed method is shown and compared to the conventional scanning method and median filtering using numerical simulations.

  13. Photoemission electron microscopy and scanning electron microscopy of Magnetospirillum magnetotacticum's magnetosome chains.

    PubMed

    Keutner, Christoph; von Bohlen, Alex; Berges, Ulf; Espeter, Philipp; Schneider, Claus M; Westphal, Carsten

    2014-10-07

    Magnetotactic bacteria are of great interdisciplinary interest, since a vast field of applications from magnetic recording media to medical nanorobots is conceivable. A key feature for a further understanding is the detailed knowledge about the magnetosome chain within the bacteria. We report on two preparation procedures suitable for UHV experiments in reflective geometry. Further, we present the results of scanning electron microscopy, as well as the first photoemission electron microscopy experiments, both accessing the magnetosomes within intact magnetotactic bacteria and compare these to scanning electron microscopy data from the literature. From the images, we can clearly identify individual magnetosomes within their chains.

  14. Band excitation method applicable to scanning probe microscopy

    DOEpatents

    Jesse, Stephen; Kalinin, Sergei V.

    2017-01-03

    Scanning probe microscopy may include a method for generating a band excitation (BE) signal and simultaneously exciting a probe at a plurality of frequencies within a predetermined frequency band based on the excitation signal. A response of the probe is measured across a subset of frequencies of the predetermined frequency band and the excitation signal is adjusted based on the measured response.

  15. Band excitation method applicable to scanning probe microscopy

    DOEpatents

    Jesse, Stephen; Kalinin, Sergei V.

    2015-08-04

    Scanning probe microscopy may include a method for generating a band excitation (BE) signal and simultaneously exciting a probe at a plurality of frequencies within a predetermined frequency band based on the excitation signal. A response of the probe is measured across a subset of frequencies of the predetermined frequency band and the excitation signal is adjusted based on the measured response.

  16. Scanning electron microscopy analysis of corrosion degradation on tinplate substrates.

    PubMed

    Zumelzu, E; Cabezas, C; Vera, A

    2003-01-01

    The degradation of electrolytic tinplate used in food containers was analysed and evaluated, using scanning electron microscopy and electrochemical measurements of microcorrosion and ion dissolution by atomic absorption to prevent food contamination caused by metal traces and to increase the durability of such tinplates.

  17. CONFOCAL LASER SCANNING MICROSCOPY OF RAT FOLLICLE DEVELOPMENT

    EPA Science Inventory

    This study used confocal laser scanning microscopy (CLSM) to study follicular development in millimeter pieces of rat ovary. To use this technology, it is essential to stain the tissue before laser excitation with the confocal microscope. Various fluorescent stains (Yo-Pro, Bo-Pr...

  18. Microstress contrast in scanning electron acoustic microscopy of ceramics

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu

    1991-01-01

    A mathematical model of image contrast in scanning electron acoustic microscopy (SEAM) due to the effect of residual stresses in materials is presented. It is found that in regions near the ends of the radial cracks induced by Vickers indentation the SEAM micrographs reveal a rather large variation of the acoustic output signal.

  19. Preparation of Articular Cartilage Specimens for Scanning Electron Microscopy.

    PubMed

    Stupina, T A

    2016-08-01

    We developed and adapted a technology for preparation of articular cartilage specimens for scanning electron microscopy. The method includes prefixation processing, fixation, washing, and dehydration of articular cartilage specimens with subsequent treatment in camphene and air-drying. The technological result consists in prevention of deformation of the articular cartilage structures. The method is simpler and cheaper than the known technologies.

  20. Scanning electron microscopy image representativeness: morphological data on nanoparticles.

    PubMed

    Odziomek, Katarzyna; Ushizima, Daniela; Oberbek, Przemyslaw; Kurzydłowski, Krzysztof Jan; Puzyn, Tomasz; Haranczyk, Maciej

    2017-01-01

    A sample of a nanomaterial contains a distribution of nanoparticles of various shapes and/or sizes. A scanning electron microscopy image of such a sample often captures only a fragment of the morphological variety present in the sample. In order to quantitatively analyse the sample using scanning electron microscope digital images, and, in particular, to derive numerical representations of the sample morphology, image content has to be assessed. In this work, we present a framework for extracting morphological information contained in scanning electron microscopy images using computer vision algorithms, and for converting them into numerical particle descriptors. We explore the concept of image representativeness and provide a set of protocols for selecting optimal scanning electron microscopy images as well as determining the smallest representative image set for each of the morphological features. We demonstrate the practical aspects of our methodology by investigating tricalcium phosphate, Ca3 (PO4 )2 , and calcium hydroxyphosphate, Ca5 (PO4 )3 (OH), both naturally occurring minerals with a wide range of biomedical applications. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  1. FOOD SURFACE TEXTURE MEASUREMENT USING REFLECTIVE CONFOCAL LASER SCANNING MICROSCOPY

    USDA-ARS?s Scientific Manuscript database

    Confocal laser scanning microscopy (CLSM) was used in the reflection mode to characterize the surface texture (roughness) of sliced food surfaces. Sandpapers of grit size between 150 and 600 were used as the height reference to standardize the CLSM hardware settings. Sandpaper particle sizes were v...

  2. '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.

  3. Microstress contrast in scanning electron acoustic microscopy of ceramics

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu

    1991-01-01

    A mathematical model of image contrast in scanning electron acoustic microscopy (SEAM) due to the effect of residual stresses in materials is presented. It is found that in regions near the ends of the radial cracks induced by Vickers indentation the SEAM micrographs reveal a rather large variation of the acoustic output signal.

  4. Scanning holographic microscopy of three-dimensional fluorescent specimens

    PubMed Central

    Indebetouw, Guy; Zhong, Wenwei

    2006-01-01

    We demonstrate experimentally the three-dimensional reconstructions of fluorescent biological specimens using scanning holographic microscopy. Three-dimensional reconstructions with transverse resolution below about 1 μm of transmission and fluorescence emission images are presented and analyzed. The limitations of the method are discussed. PMID:16783434

  5. CONFOCAL LASER SCANNING MICROSCOPY OF RAT FOLLICLE DEVELOPMENT

    EPA Science Inventory

    This study used confocal laser scanning microscopy (CLSM) to study follicular development in millimeter pieces of rat ovary. To use this technology, it is essential to stain the tissue before laser excitation with the confocal microscope. Various fluorescent stains (Yo-Pro, Bo-Pr...

  6. Writing silica structures in liquid with scanning transmission electron microscopy.

    PubMed

    van de Put, Marcel W P; Carcouët, Camille C M C; Bomans, Paul H H; Friedrich, Heiner; de Jonge, Niels; Sommerdijk, Nico A J M

    2015-02-04

    Silica nanoparticles are imaged in solution with scanning transmission electron microscopy (STEM) using a liquid cell with silicon nitride (SiN) membrane windows. The STEM images reveal that silica structures are deposited in well-defined patches on the upper SiN membranes upon electron beam irradiation. The thickness of the deposits is linear with the applied electron dose. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrate that the deposited patches are a result of the merging of the original 20 nm-diameter nanoparticles, and that the related surface roughness depends on the electron dose rate used. Using this approach, sub-micrometer scale structures are written on the SiN in liquid by controlling the electron exposure as function of the lateral position. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Manipulations of atoms and molecules by scanning probe microscopy.

    PubMed

    Tseng, Ampere A; Li, Zhuang

    2007-08-01

    Scanning probe microscopy (SPM), including scanning tunneling microscopy (STM) and atomic force microscopy (AFM), has become a powerful tool in building nanoscale structures required by modern industry. In this article, the use of SPM for the manipulation of atoms and molecules for patterning nanostructures for opt-electronic and biomedical applications is reviewed. The principles and procedures of manipulation using STM and AFM-based technologies are presented with an emphasis on their ability to create a wide variety of nanostructures for different applications. The interaction among the atoms/molecules, surface, and tip are discussed. The approaches for positioning the atom/molecule from and to the desired locations and for precisely controlling its movement are elaborated for each specific manipulation technique. As an AFM-based technique, the dip-pen nanolithography is also included. Finally, concluding remarks on technological improvement and future research is provided.

  8. The use of scanning probe microscopy to characterize polymer blends

    SciTech Connect

    Joseph, T.; Yao, L.; Beatty, C.L.

    1996-12-31

    The use of scanning probe microscopy for the examination of atomic scale phenomena in polymers has been well documented, but the use of scanning probe microscopy to examine submicron scale structures has not been well documented. The purpose of this project was to examine the structure of polymer blends on a submicron scale. Two different systems were studied; a blend of recycled thermoplastics and a blend of ground rubber tire particles in a polystyrene matrix. Topographical images, z modulation plots, internal sensor measurements, and lateral force microscopy images were obtained for both systems. The plots were compared to the structures that we were expected to obtain. A second method of mathematical analysis, fractal dimension measurement, was also performed on the topographical images. Fractal dimension measurement has been correlated to fracture toughness in homopolymers, but the correlation has not been established for polymer blends. Comparison of both methods will be shown.

  9. Scanning ion conductance microscopy studies of amyloid fibrils at nanoscale

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Cho, Sang-Joon; Busuttil, Katerina; Wang, Chen; Besenbacher, Flemming; Dong, Mingdong

    2012-05-01

    Atomic force microscopy (AFM) has developed to become a very versatile nano-scale technique to reveal the three-dimensional (3D) morphology of amyloid aggregates under physiological conditions. However, the imaging principle of AFM is based on measuring the `force' between a sharp tip and a given nanostructure, which may cause mechanical deformation of relatively soft objects. To avoid the deformation, scanning ion conductance microscopy (SICM) is an alternative scanning probe microscopy technique, operating with alternating current mode. Here we can indeed reveal the 3D morphology of amyloid fibrils and it is capable of exploring proteins with nanoscale resolution. Compared with conventional AFM, we show that SICM can provide precise height measurements of amyloid protein aggregates, a feature that enables us to obtain unique insight into the detailed nucleation and growth mechanisms behind amyloid self-assembly.

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

    PubMed

    Hempel, Casper

    2017-07-01

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

  11. Laser scanning saturated structured illumination microscopy based on phase modulation

    NASA Astrophysics Data System (ADS)

    Huang, Yujia; Zhu, Dazhao; Jin, Luhong; Kuang, Cuifang; Xu, Yingke; Liu, Xu

    2017-08-01

    Wide-field saturated structured illumination microscopy has not been widely used due to the requirement of high laser power. We propose a novel method called laser scanning saturated structured illumination microscopy (LS-SSIM), which introduces high order of harmonics frequency and greatly reduces the required laser power for SSIM imaging. To accomplish that, an excitation PSF with two peaks is generated and scanned along different directions on the sample. Raw images are recorded cumulatively by a CCD detector and then reconstructed to form a high-resolution image with extended optical transfer function (OTF). Our theoretical analysis and simulation results show that LS-SSIM method reaches a resolution of 0.16 λ, equivalent to 2.7-fold resolution than conventional wide-field microscopy. In addition, LS-SSIM greatly improves the optical sectioning capability of conventional wide-field illumination system by diminishing our-of-focus light. Furthermore, this modality has the advantage of implementation in multi-photon microscopy with point scanning excitation to image samples in greater depths.

  12. Investigations in optoelectronic image processing in scanning laser microscopy

    NASA Astrophysics Data System (ADS)

    Chaliha, Hiranya Kumar

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

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

    NASA Astrophysics Data System (ADS)

    Gregor, Ingo; Ros, Robert; Enderlein, Jörg

    2017-02-01

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

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

    PubMed Central

    Negrean, Adrian; Mansvelder, Huibert D.

    2014-01-01

    In laser-scanning microscopy often an off-the-shelf achromatic doublet is used as a scan lens which can reduce the available diffraction-limited field-of-view (FOV) by a factor of 3 and introduce chromatic aberrations that are scan angle dependent. Here we present several simple lens designs of superior quality that fully make use of high-NA low-magnification objectives, offering diffraction-limited imaging over a large FOV and wavelength range. We constructed a two-photon laser-scanning microscope with optimized custom lenses which had a near diffraction limit point-spread-function (PSF) with less than 3.6% variation over a 400 µm FOV and less than 0.5 µm lateral color between 750 and 1050 nm. PMID:24877017

  15. Scanning Tunneling Microscopy methods for spectroscopic imaging of subsurface interfaces

    NASA Technical Reports Server (NTRS)

    Bell, L. D.; Kaiser, W. J.

    1988-01-01

    A new method for spatially-resolved, spectroscopic investigation of subsurface interface structure has been developed. The method, Ballistic Electron Emission Microscopy (BEEM), is based on Scanning Tunneling Microscopy (STM) techniques. BEEM combines STM vacuum tunneling with unique ballistic electron spectroscopy capabilities. BEEM enables, for the first time, direct imaging of subsurface interface electronic properties with nanometer spatial resolution. STM topographic images of surface structure and BEEM images of subsurface properties are obtained simultaneously. BEEM capabilities are demonstrated by investigation of important metal-semiconductor interfaces.

  16. Image scanning microscopy using a SPAD detector array (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Castello, Marco; Tortarolo, Giorgio; Buttafava, Mauro; Tosi, Alberto; Sheppard, Colin J. R.; Diaspro, Alberto; Vicidomini, Giuseppe

    2017-02-01

    The use of an array of detectors can help overcoming the traditional limitation of confocal microscopy: the compromise between signal and theoretical resolution. Each element independently records a view of the sample and the final image can be reconstructed by pixel reassignment or by inverse filtering (e.g. deconvolution). In this work, we used a SPAD array of 25 detectors specifically designed for this goal and our scanning microscopy control system (Carma) to acquire the partial images and to perform online image processing. Further work will be devoted to optimize the image reconstruction step and to improve the fill-factor of the detector.

  17. Scanning conductance microscopy investigations on fixed human chromosomes.

    PubMed

    Clausen, Casper Hyttel; Lange, Jacob Moresco; Jensen, Linda Boye; Shah, Pranjul Jaykumar; Dimaki, Maria Ioannou; Svendsen, Winnie Edith

    2008-02-01

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

  18. Scanning Tunneling Microscopy methods for spectroscopic imaging of subsurface interfaces

    NASA Technical Reports Server (NTRS)

    Bell, L. D.; Kaiser, W. J.

    1988-01-01

    A new method for spatially-resolved, spectroscopic investigation of subsurface interface structure has been developed. The method, Ballistic Electron Emission Microscopy (BEEM), is based on Scanning Tunneling Microscopy (STM) techniques. BEEM combines STM vacuum tunneling with unique ballistic electron spectroscopy capabilities. BEEM enables, for the first time, direct imaging of subsurface interface electronic properties with nanometer spatial resolution. STM topographic images of surface structure and BEEM images of subsurface properties are obtained simultaneously. BEEM capabilities are demonstrated by investigation of important metal-semiconductor interfaces.

  19. Surface resistivity estimation by scanning surface potential microscopy.

    PubMed

    Rakocevic, Z; Popovic, N; Bogdanov, Z; Goncic, B; Strbac, S

    2008-06-01

    Nickel was sputter deposited on a glass with a thin film thickness of 600 nm under either in an argon atmosphere or under a partial pressure of nitrogen of either 1.3 x 10(-4) or 4 x 10(-4) mbar. Atomic force microscopy and scanning surface potential microscopy (SSPM) were used to study the morphology and to estimate the surface resistivity of the obtained Ni thin films taking into account surface-roughness effects. For the three samples investigated, the surface resistivity values as estimated using SSPM were in good agreement with the results obtained by standard four-point probe measurements.

  20. Ultrafast Photon Counting Applied to Resonant Scanning STED Microscopy

    PubMed Central

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

    2014-01-01

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

  1. Insights into the regulation of transcription by scanning force microscopy.

    PubMed

    Dame, R T; Wyman, C; Goosen, N

    2003-12-01

    The scanning force microscope (SFM) is a valuable tool for the structural analysis of complexes between protein(s) and DNA. In recent years the application of scanning force microscopy to the field of transcription regulation has been reported in numerous studies. Using this technique, novel insights could be obtained into the architecture and dynamics of complexes, which are relevant to the transcription process and the mechanisms by which this process is regulated. In this article an overview is given of SFM studies addressing, in particular, topics in the field of transcription in prokaryotic organisms.

  2. Development of first ever scanning probe microscopy capabilities for plutonium

    DOE PAGES

    Beaux, Miles F.; Cordoba, Miguel Santiago; Zocco, Adam T.; ...

    2017-04-01

    Scanning probe microscopy capabilities have been developed for plutonium and its derivative compounds. Specifically, a scanning tunneling microscope and an atomic force microscope housed in an ultra-high vacuum system and an inert atmosphere glove box, respectively, were prepared for the introduction of small non-dispersible δ-Pu coupons. Experimental details, procedures, and preliminary imaging of δ-Pu coupons are presented to demonstrate the functionality of these new capabilities. In conclusion, these first of a kind capabilities for plutonium represent a significant step forward in the ability to characterize and understand plutonium surfaces with high spatial resolution.

  3. Development of first ever scanning probe microscopy capabilities for plutonium

    NASA Astrophysics Data System (ADS)

    Beaux, Miles F.; Cordoba, Miguel Santiago; Zocco, Adam T.; Vodnik, Douglas R.; Ramos, Michael; Richmond, Scott; Moore, David P.; Venhaus, Thomas J.; Joyce, Stephen A.; Usov, Igor O.

    2017-04-01

    Scanning probe microscopy capabilities have been developed for plutonium and its derivative compounds. Specifically, a scanning tunneling microscope and an atomic force microscope housed in an ultra-high vacuum system and an inert atmosphere glove box, respectively, were prepared for the introduction of small non-dispersible δ-Pu coupons. Experimental details, procedures, and preliminary imaging of δ-Pu coupons are presented to demonstrate the functionality of these new capabilities. These first of a kind capabilities for plutonium represent a significant step forward in the ability to characterize and understand plutonium surfaces with high spatial resolution.

  4. Phase modulation mode of scanning ion conductance microscopy

    SciTech Connect

    Li, Peng; Zhang, Changlin; Liu, Lianqing E-mail: gli@engr.pitt.edu; Wang, Yuechao; Yang, Yang; Li, Guangyong E-mail: gli@engr.pitt.edu

    2014-08-04

    This Letter reports a phase modulation (PM) mode of scanning ion conductance microscopy. In this mode, an AC current is directly generated by an AC voltage between the electrodes. The portion of the AC current in phase with the AC voltage, which is the current through the resistance path, is modulated by the tip-sample distance. It can be used as the input of feedback control to drive the scanner in Z direction. The PM mode, taking the advantages of both DC mode and traditional AC mode, is less prone to electronic noise and DC drift but maintains high scanning speed. The effectiveness of the PM mode has been proven by experiments.

  5. Magnetic force microscopy of colossal magneto-resistive materials and superconductors

    NASA Astrophysics Data System (ADS)

    Lu, Qingyou

    Using a home-built low temperature piezo-driven magnetic force microscope (LT-PD-MFM), we have studied the magnetic domain behaviors in colossal magneto-resistive (CMR) thin films, the vortex behavior in high TC superconducting (HTCS) thin films as well as the localized penetration depth in a Yttrium(1)Barium(2)Copper(3)Oxygen(7) single crystal. We have obtained MFM images of domains in CMR films for temperatures from close to TC to far below TC. Domains behave differently for these two temperature zones. Well below TC, neighboring domains exhibit strong interdomain coupling. External magnetic fields can split domains more easily than rearrange them. As temperature increases, domain interactions become weaker with a reduced magnetization, and are subject to moving, splitting or merging. They are still traceable in the presence of a sample scratch. As temperature drops from TC, domains increase in magnetization. The weak interdomain interactions and high fluctuations make domain tracing impossible if there are no topographic defects. Sample scratches tend to pin domains for T ˜ TC. Current flow in CMR films can split domains. This splitting can be both reversible and irreversible when current is turned on and off. Lattice mismatch between a CMR film and a substrate leads to a stress that results in smaller domains. The magnetization of these smaller domains does not cancel out, resulting in "large-scale" domains if detected from a longer distance from the sample. Images of superconducting vortices in BSSCO films show that they grow with temperature, which is compared with the theory. The theory fits our experimental data well. We also measured the gradient of the levitation force between a magnetic tip and a superconducting single crystal as a function of the tip-sample distance. A series of these measurements were performed at different temperatures. By comparing these data with the theory in which the penetration depth lambda and the TC are parameters to be

  6. Axial scanning in confocal microscopy employing adaptive lenses (CAL).

    PubMed

    Koukourakis, Nektarios; Finkeldey, Markus; Stürmer, Moritz; Leithold, Christoph; Gerhardt, Nils C; Hofmann, Martin R; Wallrabe, Ulrike; Czarske, Jürgen W; Fischer, Andreas

    2014-03-10

    In this paper we analyze the capability of adaptive lenses to replace mechanical axial scanning in confocal microscopy. The adaptive approach promises to achieve high scan rates in a rather simple implementation. This may open up new applications in biomedical imaging or surface analysis in micro- and nanoelectronics, where currently the axial scan rates and the flexibility at the scan process are the limiting factors. The results show that fast and adaptive axial scanning is possible using electrically tunable lenses but the performance degrades during the scan. This is due to defocus and spherical aberrations introduced to the system by tuning of the adaptive lens. These detune the observation plane away from the best focus which strongly deteriorates the axial resolution by a factor of ~2.4. Introducing balancing aberrations allows addressing these influences. The presented approach is based on the employment of a second adaptive lens, located in the detection path. It enables shifting the observation plane back to the best focus position and thus creating axial scans with homogeneous axial resolution. We present simulated and experimental proof-of-principle results.

  7. A Correlative Optical Microscopy and Scanning Electron Microscopy Approach to Locating Nanoparticles in Brain Tumors

    PubMed Central

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

    2014-01-01

    The growing use of nanoparticles in biomedical applications, including cancer diagnosis and treatment, demands the capability to exactly locate them within complex biological systems. In this work a correlative optical and scanning electron microscopy technique was developed to locate and observe multi-modal gold core nanoparticle accumulation in brain tumor models. Entire brain sections from mice containing orthotopic brain tumors injected intravenously with nanoparticles were imaged using both optical microscopy to identify the brain tumor, and scanning electron microscopy to identify the individual nanoparticles. Gold-based nanoparticles were readily identified in the scanning electron microscope using backscattered electron imaging as bright spots against a darker background. This information was then correlated to determine the exact location of the nanoparticles within the brain tissue. The nanoparticles were located only in areas that contained tumor cells, and not in the surrounding healthy brain tissue. This correlative technique provides a powerful method to relate the macro- and micro-scale features visible in light microscopy with the nanoscale features resolvable in scanning electron microscopy. PMID:25464144

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

    PubMed

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

    2015-01-01

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

  9. Focused ion beam scanning electron microscopy in biology.

    PubMed

    Kizilyaprak, C; Daraspe, J; Humbel, B M

    2014-06-01

    Since the end of the last millennium, the focused ion beam scanning electron microscopy (FIB-SEM) has progressively found use in biological research. This instrument is a scanning electron microscope (SEM) with an attached gallium ion column and the 2 beams, electrons and ions (FIB) are focused on one coincident point. The main application is the acquisition of three-dimensional data, FIB-SEM tomography. With the ion beam, some nanometres of the surface are removed and the remaining block-face is imaged with the electron beam in a repetitive manner. The instrument can also be used to cut open biological structures to get access to internal structures or to prepare thin lamella for imaging by (cryo-) transmission electron microscopy. Here, we will present an overview of the development of FIB-SEM and discuss a few points about sample preparation and imaging.

  10. A fast image simulation algorithm for scanning transmission electron microscopy.

    PubMed

    Ophus, Colin

    2017-01-01

    Image simulation for scanning transmission electron microscopy at atomic resolution for samples with realistic dimensions can require very large computation times using existing simulation algorithms. We present a new algorithm named PRISM that combines features of the two most commonly used algorithms, namely the Bloch wave and multislice methods. PRISM uses a Fourier interpolation factor f that has typical values of 4-20 for atomic resolution simulations. We show that in many cases PRISM can provide a speedup that scales with f(4) compared to multislice simulations, with a negligible loss of accuracy. We demonstrate the usefulness of this method with large-scale scanning transmission electron microscopy image simulations of a crystalline nanoparticle on an amorphous carbon substrate.

  11. Elemental imaging of cartilage by scanning x-ray microscopy

    SciTech Connect

    Buckley, C.J.; Foster, G.F.; Burge, R.E. ); Ali, S.Y.; Scotchford, C.A. , Royal National Orthopaedic Hospital, Stanmore, Middlesex ); Kirz, J. ); Rivers, M.L. )

    1992-01-01

    Elemental imaging via scanning transmission x-ray microscopy (STXM) and scanning fluorescence x-ray microscopy (SFXM) has been used to image calcium deposits in cartilage. In the case of STXM, 0.1 {mu}m thick sections were imaged to investigate the proximity of calcium deposits in relation to chondrocyte cells. The resolution available was 0.5 {mu}m, and field widths of up to 25 {mu}m were used at this resolution. The resolution available in SFXM was 10 {mu}m, and field widths of up to 2 mm were used at this resolution on 5-{mu}m thick specimens. Together these techniques were used to map calcium deposits at the cellular level, and at the full tissue size level.

  12. Big, Deep, and Smart Data in Scanning Probe Microscopy

    DOE PAGES

    Kalinin, Sergei V.; Strelcov, Evgheni; Belianinov, Alex; ...

    2016-09-27

    Scanning probe microscopy techniques open the door to nanoscience and nanotechnology by enabling imaging and manipulation of structure and functionality of matter on nanometer and atomic scales. We analyze the discovery process by SPM in terms of information flow from tip-surface junction to the knowledge adoption by scientific community. Furthermore, we discuss the challenges and opportunities offered by merging of SPM and advanced data mining, visual analytics, and knowledge discovery technologies.

  13. Detecting damage in steel with scanning SQUID microscopy

    SciTech Connect

    Lee, Tae-Kyu; Clatterbuck, David; Morris Jr., J.W.; Shaw, T.J.; McDermott R.; Clarke, John

    2001-09-04

    A ''Holy Grail'' of NDE research is a non-destructive method for measuring fatigue damage prior to crack initiation. High-Tc scanning SQUID microscopy may be a useful tool. Because of the exceptional magnetic sensitivity of this technique, fatigue damage can be detected well before microcrack initiation, and in the absence of other obvious microstructure or property changes. Given the spatial resolution of the technique, undamaged material can be located and used to set internal standards.

  14. Single-nanoparticle-terminated tips for scanning probe microscopy.

    PubMed

    Vakarelski, Ivan U; Higashitani, Ko

    2006-03-28

    We have developed a wet-chemistry procedure to attach a 10-40 nm colloidal gold nanoparticle to the top of a scanning probe microscopy (SPM) probe tip, making experiments of single nanoparticle interaction possible. This procedure of particle attachment is flexible and can be modified to attach nanoparticles of different kinds and sizes. The single-nanoparticle-terminated tips also have potential in various other applications, such as probes of enhanced sensitivity for optical and magnetic modes SPM.

  15. Big, Deep, and Smart Data in Scanning Probe Microscopy

    SciTech Connect

    Kalinin, Sergei V.; Strelcov, Evgheni; Belianinov, Alex; Somnath, Suhas; Vasudevan, Rama K.; Lingerfelt, Eric J.; Archibald, Richard K.; Chen, Chaomei; Proksch, Roger; Laanait, Nouamane; Jesse, Stephen

    2016-09-27

    Scanning probe microscopy techniques open the door to nanoscience and nanotechnology by enabling imaging and manipulation of structure and functionality of matter on nanometer and atomic scales. We analyze the discovery process by SPM in terms of information flow from tip-surface junction to the knowledge adoption by scientific community. Furthermore, we discuss the challenges and opportunities offered by merging of SPM and advanced data mining, visual analytics, and knowledge discovery technologies.

  16. Preparation of silver tips for scanning tunneling microscopy imaging

    NASA Astrophysics Data System (ADS)

    Iwami, M.; Uehara, Y.; Ushioda, S.

    1998-11-01

    A simple reliable preparation method of silver tips for scanning tunneling microscopy imaging with atomic resolution is presented. The procedure is based on two-step electrochemical processing; ac electropolishing and subsequent dc electroetching. The quality of the tip is improved by applying high bias voltage pulses while the tip is within tunneling range. This indicates that the end of the tips are sharpened by field evaporation of silver ions.

  17. Scanning angle interference microscopy reveals cell dynamics at the nanoscale.

    PubMed

    Paszek, Matthew J; DuFort, Christopher C; Rubashkin, Matthew G; Davidson, Michael W; Thorn, Kurt S; Liphardt, Jan T; Weaver, Valerie M

    2012-07-01

    Emerging questions in cell biology necessitate nanoscale imaging in live cells. Here we present scanning angle interference microscopy, which is capable of localizing fluorescent objects with nanoscale precision along the optical axis in motile cellular structures. We use this approach to resolve nanotopographical features of the cell membrane and cytoskeleton as well as the temporal evolution, three-dimensional architecture and nanoscale dynamics of focal adhesion complexes.

  18. Correcting nonlinear drift distortion of scanning probe and scanning transmission electron microscopies from image pairs with orthogonal scan directions.

    PubMed

    Ophus, Colin; Ciston, Jim; Nelson, Chris T

    2016-03-01

    Unwanted motion of the probe with respect to the sample is a ubiquitous problem in scanning probe and scanning transmission electron microscopies, causing both linear and nonlinear artifacts in experimental images. We have designed a procedure to correct these artifacts by using orthogonal scan pairs to align each measurement line-by-line along the slow scan direction, by fitting contrast variation along the lines. We demonstrate the accuracy of our algorithm on both synthetic and experimental data and provide an implementation of our method. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Correcting nonlinear drift distortion of scanning probe and scanning transmission electron microscopies from image pairs with orthogonal scan directions

    DOE PAGES

    Ophus, Colin; Ciston, Jim; Nelson, Chris T.

    2015-12-10

    Unwanted motion of the probe with respect to the sample is a ubiquitous problem in scanning probe and scanning transmission electron microscopies, causing both linear and nonlinear artifacts in experimental images. We have designed a procedure to correct these artifacts by using orthogonal scan pairs to align each measurement line-by-line along the slow scan direction, by fitting contrast variation along the lines. We demonstrate the accuracy of our algorithm on both synthetic and experimental data and provide an implementation of our method.

  20. Paleomagnetism on submillimeter scales with scanning magnetic microscopy

    NASA Astrophysics Data System (ADS)

    Andrade Lima, E.; Weiss, B. P.; Fu, R. R.; Suavet, C. R.; Bruno, A. C.

    2013-12-01

    The development of superconducting moment magnetometers three decades ago enabled paleomagnetic studies to be extended to previously inaccessible weakly magnetic samples like sediments, single silicate crystals, and lunar rocks. However, there still are a number of very important questions in geomagnetism and planetary magnetism that have remained unsolved owing to insufficient moment sensitivity and spatial resolution. Examples include retrieving records of magnetic fields in the primitive solar nebula from single meteorite grains, establishing when the geodynamo originated from individual zircon crystals, and understanding the complex magnetostatic interactions in metal grains that plague paleointensity studies of extraterrestrial rocks. Here we describe how we are tackling these problems using two new techniques in scanning magnetic microscopy: SQUID microscopy and magnetic tunnel junction (MTJ) microscopy. Scanning SQUID microscopes offer unparalleled moment sensitivity, but spatial resolution is limited to ~100 μm due to cryogenic constraints. On the other hand, scanning MTJ microscopes operate at room temperature and achieve much higher spatial resolutions (< 10 μm) at the expense of decreased field sensitivity. However, because the MTJ sensor can be placed at very close proximity to the sample, the effective magnetic moment sensitivity is often sufficient for many applications. SQUID microscopes can be utilized as ultra-high sensitivity moment magnetometers (better than 10^-15 Am2) and are particularly powerful to analyze unresolved weak sources such as individual chondrules and single-crystal zircons. The high spatial resolution of MTJ microscopes makes them especially suited to identifying the spatial distribution of magnetic minerals in rocks with complex compositions, such as meteorites and lunar rocks. We present recent results from our paleo- and rock magnetic studies of zircon crystals using SQUID microscopy and briefly discuss the fundamental

  1. Characterization of carbon nanotubes by scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Gallagher, Mark J.; Chen, Dong; Jacobsen, Bruce P.; Sarid, Dror; Lamb, Lowell D.; Tinker, Frank A.; Jiao, Jun; Huffman, Donald R.; Seraphin, Supapan; Zhou, Dan

    Carbon nanotubes, fabricated by the Ebbesen-Ajayan method, were imaged using scanning tunneling microscopy (STM) and atomic force microscopy (AFM) in air and were compared to images obtained with high-resolution transmission electron microscopy (HRTEM). The HRTEM images revealed an abundance of elongated structures ranging in diameter from 3.0 to 30 nm, and with lengths of up to 0.8 μm. Many of the structures possessed several graphitic shells as if the tubes were nested one in the other. Reproducible images of the tubular structures, typically 20 nm in diameter and with a large variation in length, were obtained with both STM and AFM when the nanotubes were deposited on hydrogen-terminated Si(111), confirming that the nested structures observed with HRTEM do indeed have a tubular morphology. No single-walled, bare nanotubes or spherical fullerenes (typical of the Krätschmer-Huffman process) were observed.

  2. Characterization of carbon nanotubes by scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Gallagher, Mark J.; Chen, Dong; Jacobsen, Bruce P.; Sarid, Dror; Lamb, Lowell D.; Tinker, Frank A.; Jiao, Jun; Huffman, Donald R.; Seraphin, Supapan; Zhou, Dan

    1993-02-01

    Carbon nanotubes, fabricated by the Ebbesen-Ajayan method, were imaged using scanning tunneling microscopy (STM) and atomic force microscopy (AFM) in air and were compared to images obtained with high-resolution transmission electron microscopy (HRTEM). The HRTEM images revealed an abundance of elongated structures ranging in diameter from 3.0 to 30 nm, and with lengths of up to 0.8 μm. Many of the structures possessed several graphitic shells as if the tubes were nested one in the other. Reproducible images of the tubular structures, typically 20 nm in diameter and with a large variation in length, were obtained with both STM and AFM when the nanotubes were deposited on hydrogen-terminated Si(111), confirming that the nested structures observed with HRTEM do indeed have a tubular morphology. No single-walled, bare nanotubes or spherical fullerenes (typical of the Krätschmer-Huffman process) were observed.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2013-01-01

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

  5. Potential Applications of Scanning Probe Microscopy in Forensic Science

    NASA Astrophysics Data System (ADS)

    Watson, G. S.; Watson, J. A.

    2007-04-01

    The forensic community utilises a myriad of techniques to investigate a wide range of materials, from paint flakes to DNA. The various microscopic techniques have provided some of the greatest contributions, e.g., FT-IR (Fourier-transform infrared) microspectroscopy utilised in copy toner discrimination, multi-layer automobile paint fragment examination, etc, SEM-EDA (scanning electron microscopy with energy dispersive analysis) used to investigate glass fragments, fibers, and explosives, and SEM in microsampling for elemental analysis, just to name a few. This study demonstrates the ability of the Scanning Probe Microscope (SPM) to analyse human fingerprints on surfaces utilising a step-and-scan feature, enabling analysis of a larger field-of-view. We also extend a line crossings study by incorporating height analysis and surface roughness measurements. The study demonstrates the potential for SPM techniques to be utilised for forensic analysis which could complement the more traditional methodologies used in such investigations.

  6. Imaging ballistic carrier trajectories in graphene using scanning gate microscopy

    SciTech Connect

    Morikawa, Sei; Masubuchi, Satoru; Dou, Ziwei; Wang, Shu-Wei; Smith, Charles G.; Connolly, Malcolm R.; Watanabe, Kenji; Taniguchi, Takashi; Machida, Tomoki

    2015-12-14

    We use scanning gate microscopy to map out the trajectories of ballistic carriers in high-mobility graphene encapsulated by hexagonal boron nitride and subject to a weak magnetic field. We employ a magnetic focusing geometry to image carriers that emerge ballistically from an injector, follow a cyclotron path due to the Lorentz force from an applied magnetic field, and land on an adjacent collector probe. The local electric field generated by the scanning tip in the vicinity of the carriers deflects their trajectories, modifying the proportion of carriers focused into the collector. By measuring the voltage at the collector while scanning the tip, we are able to obtain images with arcs that are consistent with the expected cyclotron motion. We also demonstrate that the tip can be used to redirect misaligned carriers back to the collector.

  7. Developments of scanning probe microscopy with stress/strain fields.

    PubMed

    Guo, H X; Fujita, D

    2011-12-01

    An innovative stress/strain fields scanning probe microscopy in ultra high vacuum (UHV) environments is developed for the first time. This system includes scanning tunneling microscope (STM) and noncontact atomic force microscope (NC-AFM). Two piezo-resistive AFM cantilever probes and STM probes used in this system can move freely in XYZ directions. The nonoptical frequency shift detection of the AFM probe makes the system compact enough to be set in the UHV chambers. The samples can be bent by an anvil driven by a step motor to induce stress and strain on their surface. With a direct current (dc) power source, the sample can be observed at room and high temperatures. A long focus microscope and a monitor are used to observe the samples and the operation of STM and AFM. Silicon(111) surface in room temperature and silicon(001) surface in high temperature with stress were investigated to check the performance of the scanning probe microscope.

  8. Simultaneous Correlative Scanning Electron and High-NA Fluorescence Microscopy

    PubMed Central

    Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Effting, Andries P. J.; Voorneveld, Philip W.; Lucas, Miriam S.; Hardwick, James C.; Wepf, Roger A.; Kruit, Pieter; Hoogenboom, Jacob P.

    2013-01-01

    Correlative light and electron microscopy (CLEM) is a unique method for investigating biological structure-function relations. With CLEM protein distributions visualized in fluorescence can be mapped onto the cellular ultrastructure measured with electron microscopy. Widespread application of correlative microscopy is hampered by elaborate experimental procedures related foremost to retrieving regions of interest in both modalities and/or compromises in integrated approaches. We present a novel approach to correlative microscopy, in which a high numerical aperture epi-fluorescence microscope and a scanning electron microscope illuminate the same area of a sample at the same time. This removes the need for retrieval of regions of interest leading to a drastic reduction of inspection times and the possibility for quantitative investigations of large areas and datasets with correlative microscopy. We demonstrate Simultaneous CLEM (SCLEM) analyzing cell-cell connections and membrane protrusions in whole uncoated colon adenocarcinoma cell line cells stained for actin and cortactin with AlexaFluor488. SCLEM imaging of coverglass-mounted tissue sections with both electron-dense and fluorescence staining is also shown. PMID:23409024

  9. 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.

  10. Atomic-scale electrochemistry on the surface of a manganite by scanning tunneling microscopy

    SciTech Connect

    Vasudevan, Rama K. Tselev, Alexander; Baddorf, Arthur P.; Gianfrancesco, Anthony G.

    2015-04-06

    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 La{sub 0.625}Ca{sub 0.375}MnO{sub 3} grown on (001) SrTiO{sub 3} 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.

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

    PubMed

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

    2015-05-01

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

  12. Environmental scanning electron microscopy gold immunolabeling in cell biology.

    PubMed

    Rosso, Francesco; Papale, Ferdinando; Barbarisi, Alfonso

    2013-01-01

    Immunogold labeling (IGL) technique has been utilized by many authors in combination with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to obtain the identification/localization of receptors and antigens, both in cells and tissues. Environmental scanning electron microscopy (ESEM) represents an important tool in biomedical research, since it does not require any severe processing of the sample, lowering the risk of generating artifacts and interfere with the IGL procedure. The absence of metal coating could yield further advantages for our purpose as the labeling detection is based on the atomic number difference between nanogold spheres and the biological material. Using the gaseous secondary electron detector, compositional contrast is easily revealed by the backscattered electron component of the signal. In spite of this fact, only few published papers present a combination of ESEM and IGL. Hereby we present our method, optimized to improve the intensity and the specificity of the labeling signal, in order to obtain a semiquantitative evaluation of the labeling signal.In particular, we used a combination of IGL and ESEM to detect the presence of a protein on the cell surface. To achieve this purpose, we chose as an experimental system 3T3 Swiss albino mouse fibroblasts and galectin-3.

  13. Scanning Ion Conductance Microscopy for Studying Biological Samples

    PubMed Central

    Happel, Patrick; Thatenhorst, Denis; Dietzel, Irmgard D.

    2012-01-01

    Scanning ion conductance microscopy (SICM) is a scanning probe technique that utilizes the increase in access resistance that occurs if an electrolyte filled glass micro-pipette is approached towards a poorly conducting surface. Since an increase in resistance can be monitored before the physical contact between scanning probe tip and sample, this technique is particularly useful to investigate the topography of delicate samples such as living cells. SICM has shown its potential in various applications such as high resolution and long-time imaging of living cells or the determination of local changes in cellular volume. Furthermore, SICM has been combined with various techniques such as fluorescence microscopy or patch clamping to reveal localized information about proteins or protein functions. This review details the various advantages and pitfalls of SICM and provides an overview of the recent developments and applications of SICM in biological imaging. Furthermore, we show that in principle, a combination of SICM and ion selective micro-electrodes enables one to monitor the local ion activity surrounding a living cell. PMID:23202197

  14. Zernike phase contrast in scanning microscopy with X-rays

    PubMed Central

    Holzner, Christian; Feser, Michael; Vogt, Stefan; Hornberger, Benjamin; Baines, Stephen B.; Jacobsen, Chris

    2011-01-01

    Scanning X-ray microscopy focuses radiation to a small spot and probes the sample by raster scanning. It allows information to be obtained from secondary signals such as X-ray fluorescence, which yields an elemental mapping of the sample not available in full-field imaging. The analysis and interpretation from these secondary signals can be considerably enhanced if these data are coupled with structural information from transmission imaging. However, absorption often is negligible and phase contrast has not been easily available. Originally introduced with visible light, Zernike phase contrast1 is a well-established technique in full-field X-ray microscopes for visualization of weakly absorbing samples2–7. On the basis of reciprocity, we demonstrate the implementation of Zernike phase contrast in scanning X-ray microscopy, revealing structural detail simultaneously with hard-X-ray trace-element measurements. The method is straightforward to implement without significant influence on the resolution of the fluorescence images and delivers complementary information. We show images of biological specimens that clearly demonstrate the advantage of correlating morphology with elemental information. PMID:21544232

  15. Zernike phase contrast in scanning microscopy with X-rays.

    PubMed

    Holzner, Christian; Feser, Michael; Vogt, Stefan; Hornberger, Benjamin; Baines, Stephen B; Jacobsen, Chris

    2010-11-01

    Scanning X-ray microscopy focuses radiation to a small spot and probes the sample by raster scanning. It allows information to be obtained from secondary signals such as X-ray fluorescence, which yields an elemental mapping of the sample not available in full-field imaging. The analysis and interpretation from these secondary signals can be considerably enhanced if these data are coupled with structural information from transmission imaging. However, absorption often is negligible and phase contrast has not been easily available. Originally introduced with visible light, Zernike phase contrast(1) is a well-established technique in full-field X-ray microscopes for visualization of weakly absorbing samples(2-7). On the basis of reciprocity, we demonstrate the implementation of Zernike phase contrast in scanning X-ray microscopy, revealing structural detail simultaneously with hard-X-ray trace-element measurements. The method is straightforward to implement without significant influence on the resolution of the fluorescence images and delivers complementary information. We show images of biological specimens that clearly demonstrate the advantage of correlating morphology with elemental information.

  16. Microvascular quantification based on contour-scanning photoacoustic microscopy

    PubMed Central

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

    2014-01-01

    Abstract. Accurate quantification of microvasculature remains of interest in fundamental pathophysiological studies and clinical trials. Current photoacoustic microscopy can noninvasively quantify properties of the microvasculature, including vessel density and diameter, with a high spatial resolution. However, the depth range of focus (i.e., focal zone) of optical-resolution photoacoustic microscopy (OR-PAM) is often insufficient to encompass the depth variations of features of interest—such as blood vessels—due to uneven tissue surfaces. Thus, time-consuming image acquisitions at multiple different focal planes are required to maintain the region of interest in the focal zone. We have developed continuous three-dimensional motorized contour-scanning OR-PAM, which enables real-time adjustment of the focal plane to track the vessels’ profile. We have experimentally demonstrated that contour scanning improves the signal-to-noise ratio of conventional OR-PAM by as much as 41% and shortens the image acquisition time by 3.2 times. Moreover, contour-scanning OR-PAM more accurately quantifies vessel density and diameter, and has been applied to studying tumors with uneven surfaces. PMID:25223708

  17. Tip/tilt-compensated through-focus scanning optical microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Jun Ho; Park, Jun Hyung; Jeong, Dohwan; Shin, Eun Ji; Park, Chris

    2016-11-01

    Through-Focus Optical Microscopy (TSOM), with nanometer scale lateral and vertical sensitivity matching those of scanning electron microscopy, has been demonstrated to be utilized for 3D inspection and metrology. There have been sensitivity and instability issues in acquiring through-focus images because TSOM 3D information is indirectly extracted by differentiating a target TSOM image from reference TSOM images. This paper first reports on the optical axis instability that occurs during the scanning process of TSOM when implemented in an existing patterned wafer inspection tool by moving the wafer plane; this is followed by quantitative confirmation of the optical/mechanical instability using a new TSOM tool on an optical bench with a Shack-Hartmann wavefront sensor and a tip/tilt sensor. Then, this paper proposes two tip/tilt compensated TSOM optical acquisition methods that can be applied with adaptive optics. The first method simply adopts a tip/tilt mirror with a quad cell in a simple closed loop, while the second method adopts a highorder deformable mirror with a Shack-Hartmann sensor. The second method is able to correct high-order residual aberrations as well as to perform through-focus scanning without z-axis movement, while the first method is easier to implement in pre-existing wafer inspection systems with only minor modification.

  18. Scanning electron microscopy: preparation and imaging for SEM.

    PubMed

    Jones, Chris G

    2012-01-01

    Scanning electron microscopy (SEM) has been almost universally applied for the surface examination and characterization of both natural and man-made objects. Although an invasive technique, developments in electron microscopy over the years has given the microscopist a much clearer choice in how invasive the technique will be. With the advent of low vacuum SEM in the 1970s (The environmental cold stage, 1970) and environmental SEM in the late 1980s (J Microsc 160(pt. 1):9-19, 1989), it is now possible in some circumstances to examine samples without preparation. However, for the examination of biological tissue and cells it is still advisable to chemically fix, dehydrate, and coat samples for SEM imaging and analysis. This chapter aims to provide an overview of SEM as an imaging tool, and a general introduction to some of the methods applied for the preparation of samples.

  19. Application of Scanning Probe Microscopy to Genetic Analysis

    NASA Astrophysics Data System (ADS)

    Sugiyama, Shigeru; Yoshino, Tomoyuki; Tsukamoto, Kazumi; Sasou, Megumi; Kuwazaki, Seigo; Takahashi, Hirokazu; Suetsugu, Yoshitaka; Narukawa, Junko; Yamamoto, Kimiko; Ohtani, Toshio

    2006-03-01

    We are developing an integrated technique involving of nanometer-size dissection of chromosome fragments by atomic force microscopy (AFM) and direct detection of the location of genome library clones by scanning near-field optical/atomic force microscopy (SNOM/AFM). The locations of nucleus organizer regions (NORs) on barley chromosomes and a bacterial artificial chromosome (BAC) clone were successfully detected by SNOM/AFM. Nanometer-scale dissection of silkworm pachytene chromosomes was also performed by AFM, and we succeeded in three successive dissection events of the chromosome region approximately 250 nm apart from each other. If this type of integrated method can be established in the near future, we will easily obtain the nucleotide sequences with positional information on chromosomes, which lead to a time- and cost-saving genome analysis technique.

  20. Imaging plasmodesmata with high-resolution scanning electron microscopy.

    PubMed

    Barton, Deborah A; Overall, Robyn L

    2015-01-01

    High-resolution scanning electron microscopy (HRSEM) is an effective tool to investigate the distribution of plasmodesmata within plant cell walls as well as to probe their complex, three-dimensional architecture. It is a useful alternative to traditional transmission electron microscopy (TEM) in which plasmodesmata are sectioned to reveal their internal substructures. Benefits of adopting an HRSEM approach to studies of plasmodesmata are that the specimen preparation methods are less complex and time consuming than for TEM, many plasmodesmata within a large region of tissue can be imaged in a single session, and three-dimensional information is readily available without the need for reconstructing TEM serial sections or employing transmission electron tomography, both of which are lengthy processes. Here we describe methods to prepare plant samples for HRSEM using pre- or postfixation extraction of cellular material in order to visualize plasmodesmata embedded within plant cell walls.

  1. Scanning electron microscopy of primate chorionic villi following ultrasonic microdissection.

    PubMed

    King, B F

    1991-01-01

    Villi from human, macaque and baboon placentae were subjected to ultrasonication after prolonged osmication, and examined by scanning electron microscopy. The technique was often successful in removing the overlying trophoblast and revealing expanses of the trophoblastic basal lamina, a conclusion corroborated by transmission electron microscopy. These preparations bore a remarkable similarity in appearance to microvascular cast preparations of the fetal vasculature. Relatively straight parallel tubules appeared to correspond in position to the location of fetal vessels in intermediate villi, whereas portions of the basal laminae of terminal villi were in the form of convoluted, branched cylinders similar to SEM images of fetal capillaries of terminal villi. The basal lamina did not have evidence of pores as has been described in some basal laminae.

  2. Chromosome observation by scanning electron microscopy using ionic liquid.

    PubMed

    Dwiranti, Astari; Lin, Linyen; Mochizuki, Eiko; Kuwabata, Susumu; Takaoka, Akio; Uchiyama, Susumu; Fukui, Kiichi

    2012-08-01

    Electron microscopy has been used to visualize chromosome since it has high resolution and magnification. However, biological samples need to be dehydrated and coated with metal or carbon before observation. Ionic liquid is a class of ionic solvent that possesses advantageous properties of current interest in a variety of interdisciplinary areas of science. By using ionic liquid, biological samples need not be dehydrated or metal-coated, because ionic liquid behaves as the electronically conducting material for electron microscopy. The authors have investigated chromosome using ionic liquid in conjunction with electron microscopy and evaluated the factors that affect chromosome visualization. Experimental conditions used in the previous studies were further optimized. As a result, prewarmed, well-mixed, and low concentration (0.5∼1.0%) ionic liquid provides well-contrasted images, especially when the more hydrophilic and the higher purity ionic liquid is used. Image contrast and resolution are enhanced by the combination of ionic liquid and platinum blue staining, the use of an indium tin oxide membrane, osmium tetroxide-coated coverslip, or aluminum foil as substrate, and the adjustment of electron acceleration voltage. The authors conclude that the ionic-liquid method is useful for the visualization of chromosome by scanning electron microscopy without dehydration or metal coating.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

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

    PubMed

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

    2012-06-01

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

  7. Scanning electron microscopy of adult Gongylonema pulchrum (Nematoda: Spirurida).

    PubMed

    Naem, S; Seifi, H; Simon, G T

    2000-05-01

    Scanning electron microscopy (SEM) was used to study the surface ultrastructure of adult worms of Gongylonema pulchrum. The anterior end in both sexes was covered by numerous cuticular platelets. There was a pair of lateral cervical papillac. The buccal opening was small and extended in the dorsoventral direction. Around the mouth a cuticular elevation enclosed the labia, and eight papillae were located laterodorsally and lateroventrally. Two large lateral amphids were seen. On the lateral sides of the female's tail, phasmidal apertures were observed. The caudal end of the male was asymmetrically alate and bore 10 pairs of papillae and two phasmidal apertures.

  8. Noise analysis for through-focus scanning optical microscopy

    PubMed Central

    Attota, Ravikiran

    2016-01-01

    A systematic noise-analysis study for optimizing data collection and data processing parameters for through-focus scanning optical microscopy (TSOM) is presented. TSOM is a three-dimensional shape metrology method that can achieve sub-nanometer measurement sensitivity by analyzing sets of images acquired through-focus using a conventional optical microscope. We show that best balance between signal-to-noise performance and acquisition time can be achieved by judicious spatial averaging. Correct background-signal subtraction of the imaging-system inhomogeneities is also critical, as well as careful alignment of the constituent images in the case of differential TSOM analysis. PMID:26872178

  9. Cooling crystallization experiments observed by in situ scanning force microscopy

    NASA Astrophysics Data System (ADS)

    Kipp, S.; Lacmann, R.

    1996-03-01

    The change in surface morphology of potassium nitrate and potassium alum has been studied in situ by means of scanning force microscopy. The supersaturation and undersaturation were varied in a cooling crystallizer under flow conditions. To keep the crystal growth rate of potassium nitrate low, the specific additive DOW FAX 3B2 had been used in different concentrations. The crystal growth rate of both systems could be determined and the growth and dissolution surface morphologies of potassium alum exhibited structures similar to those of microscopic measurements.

  10. Scanning Conductance Microscopy of Carbon Nanotubes and Polyethylene Oxide Nanofibers

    NASA Astrophysics Data System (ADS)

    Staii, Cristian; Pinto, Nicholas J.; Johnson, Alan T.

    2004-09-01

    We have developed a quantitative model that explains the phase shifts observed in Scanning Conductance Microscopy, by considering the change in the total capacitance of the tip-sample-substrate system. We show excellent agreement with data on samples of (conducting) single wall carbon nanotubes and insulating polyethylene oxide (PEO) nanofibers. Data for large diameter, conducting doped polyaniline/PEO nanofibers are qualitatively explained. This quantitative approach is used to determine the dielectric constant of PEO nanofiber ɛf = 2.88 ± 0.12, a general method that can be extended to other dielectric nanowires.

  11. Scanning Transmission X-ray microscopy Imaging of Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Gilles, M. K.; Kilcoyne, A.; Tyliszczak, T.; Shuh, D. K.; Fakra, S.; Robinson, M.; Chase, K.

    2003-12-01

    Scanning transmission x-ray microscopes (STXM) are used to image a diversity of carbon and metal containing items such as biofilms in soils, magnetic materials, polymers and meteorites. Studies on particles collected on SiO2 filters from biomass burns in Flagstaff, Arizona and individual aerosols collected in South Africa on TEM grids are underway at beamlines 5.3.2 and 11.0.2 at the Advanced Light Source of Lawrence Berkeley National Laboratory. Sub micron particles are imaged in the transmission mode over the energy range of 280 - 1900 eV. Spectromicroscopic studies on individual particles using near edge x-ray absorption fine structure (NEXAFS) probe multiple species within or on the same particle. In (STXM) an X-ray beam is focused with a zone plate onto a sample and the transmitted radiation is detected. Since the signal is obtained in the transmission mode, optically thin samples are required. Hence, atmospheric aerosols with submicron thickness and diameter are well suited for this method. Near edge spectra of various elements were scanned in step sizes from 0.1-0.5 eV around characteristic absorption edges, creating 2 dimensional images at each energy. While STXM images are taken with a lower spatial resolution (currently 40 nm) than microscopies such as scanning electron microscopy, transmission electron microscopy, and atomic force microscopy, detailed chemical information with spatial distributions, and oxidation states is obtained. A particular focus of this work is to obtain more detailed information on the type of carbons, multiply, or singly bonded and whether or not carbon is bonded to oxygen. The ultimate goal is discrimination between organic and black carbon within individual aerosol particles and determining if organic carbon, black carbon, and metal species are distributed homogeneously throughout aerosol particles. Initial scans of the samples from Flagstaff show spectral evidence of aromatic carbon, without distinct C=O signatures. NEXAFS

  12. Measurement of dihedral angles by scanning electron microscopy.

    NASA Technical Reports Server (NTRS)

    Achutaramayya, G.; Scott, W. D.

    1973-01-01

    The extension of Hoover's (1971) technique to the case of dihedral-angle measurement is described. Dihedral angles are often determined by interferometry on thermally grooved grain boundaries to obtain information on relative interfacial energies. In the technique considered the measured angles approach the true angles as the tilt angle approaches 90 deg. It is pointed out that the scanning electron microscopy method provides a means of seeing the real root of a groove at a lateral magnification which is higher than that obtainable with interferometry.

  13. Free-standing graphene by scanning transmission electron microscopy.

    PubMed

    Song, F Q; Li, Z Y; Wang, Z W; He, L; Han, M; Wang, G H

    2010-11-01

    Free-standing graphene sheets have been imaged by scanning transmission electron microscopy (STEM). We show that the discrete numbers of graphene layers enable an accurate calibration of STEM intensity to be performed over an extended thickness and with single atomic layer sensitivity. We have applied this calibration to carbon nanoparticles with complex structures. This leads to the direct and accurate measurement of the electron mean free path. Here, we demonstrate potentials using graphene sheets as a novel mass standard in STEM-based mass spectrometry.

  14. Recent advances in submolecular resolution with scanning probe microscopy.

    PubMed

    Gross, Leo

    2011-04-01

    Recently scanning probe microscopy has made tremendous progress in imaging organic molecules with high lateral resolution. Atoms and bonds within individual molecules have been clearly resolved, indicating the exciting potential of this technique for studying molecular structures, bonding within and between molecules, molecular conformational changes and chemical reactions at the single-molecule level. It turns out that the key step enabling such studies is an atomically controlled functionalization of the microscope tip. In this Perspective, the different techniques used for high-resolution molecular imaging, their implementations, advantages and limitations are described, and possible scientific areas of applications are discussed.

  15. Scanning near-field optical microscopy: application to biological sciences

    NASA Astrophysics Data System (ADS)

    Lim, Tuan-Kay

    2001-12-01

    Recent developments in genetic engineering and medical informatics offer enormous potential for biotechnology. However, key enabling technologies, such as medical instrumentation and analytical tools, are required to support further research in this field. The scanning near-field optical microscopy (SNOM) is one of the key instruments for research in these areas. In this paper, we review the synergy of the SNOM with other technologies for the imaging and characterization of biological materials. Based on this review, the components and systems design parameters are summarized.

  16. Scanning Tunneling Microscopy analysis of space-exposed polymer films

    NASA Technical Reports Server (NTRS)

    Kalil, Carol R.; Young, Philip R.

    1993-01-01

    The characterization of the surface of selected space-exposed polymer films by Scanning Tunneling Microscopy (STM) is reported. Principles of STM, an emerging new technique for materials analysis, are reviewed. The analysis of several films which received up to 5.8 years of low Earth orbital (LEO) exposure onboard the NASA Long Duration Exposure Facility (LDEF) is discussed. Specimens included FEP Teflon thermal blanket material, Kapton film, and several experimental polymer films. Ultraviolet and atomic oxygen-induced crazing and erosion are described. The intent of this paper is to demonstrate how STM is enhancing the understanding of LEO space environmental effects on polymer films.

  17. Measurement of dihedral angles by scanning electron microscopy.

    NASA Technical Reports Server (NTRS)

    Achutaramayya, G.; Scott, W. D.

    1973-01-01

    The extension of Hoover's (1971) technique to the case of dihedral-angle measurement is described. Dihedral angles are often determined by interferometry on thermally grooved grain boundaries to obtain information on relative interfacial energies. In the technique considered the measured angles approach the true angles as the tilt angle approaches 90 deg. It is pointed out that the scanning electron microscopy method provides a means of seeing the real root of a groove at a lateral magnification which is higher than that obtainable with interferometry.

  18. Energy-Filtered Scanning Tunneling Microscopy using a Semiconductor Tip

    NASA Astrophysics Data System (ADS)

    Sutter, P.; Zahl, P.; Sutter, E.; Bernard, J. E.

    2003-04-01

    The use of cleaved, [111]-oriented monocrystalline InAs probe tips enables state-specific imaging in constant-current filled-state scanning tunneling microscopy. On Si(111)-(7×7), the adatom or rest-atom dangling-bond states can thus be mapped selectively at different tip-sample bias. This state-selective imaging is made possible by energy gaps in the projected bulk band structure of the semiconductor probe. The lack of extended bulk states in these gaps gives rise to efficient energy filtering of the tunneling current, to which only sample states not aligned with a gap contribute significantly.

  19. Contrast distortion induced by modulation voltage in scanning capacitance microscopy

    NASA Astrophysics Data System (ADS)

    Chang, M. N.; Hu, C. W.; Chou, T. H.; Lee, Y. J.

    2012-08-01

    With a dark-mode scanning capacitance microscopy (SCM), we directly observed the influence of SCM modulation voltage (MV) on image contrasts. For electrical junctions, an extensive modulated area induced by MV may lead to noticeable changes in the SCM signal phase and intensity, resulting in a narrowed junction image and a broadened carrier concentration profile. This contrast distortion in SCM images may occur even if the peak-to-peak MV is down to 0.3 V. In addition, MV may shift the measured electrical junction depth. The balance of SCM signals components explain these MV-induced contrast distortions.

  20. Integrated micro ring resonator displacement sensor for scanning probe microscopies

    NASA Astrophysics Data System (ADS)

    Kiyat, Isa; Kocabas, Coskun; Aydinli, Atilla

    2004-03-01

    We describe a novel displacement sensor for scanning probe microscopies using an integrated optical micro ring resonator. This device operates by means of monitoring the changes in the transmission spectrum of a high finesse micro ring resonator. Finite element method simulations were carried out to obtain the optimum sensor design and finite difference time domain simulation was used to obtain the transfer characteristics of micro ring resonators. Operation principles and sensitivity calculations are discussed in detail. To achieve high sensitivity, we have studied different types of ring resonator. The highest sensitivity is obtained in a race-track resonator. This new design should provide sensitivities as high as ~10-4 Å-1.

  1. Scanned gate microscopy of a one-dimensional quantum dot.

    PubMed

    Zhang, Lingfeng M; Fogler, Michael M

    2006-10-01

    We analyze electrostatic interaction between a sharp conducting tip and a thin one-dimensional wire, e.g., a carbon nanotube, in a scanned gate microscopy (SGM) experiment. The problem is analytically tractable if the wire resides on a thin dielectric substrate above a metallic backgate. The characteristic spatial scale of the electrostatic coupling to the tip is equal to its height above the substrate. Numerical simulations indicate that imaging of individual electrons by SGM is possible once the mean electron separation exceeds this scale (typically, a few tens of nm). Differences between weakly and strongly invasive SGM regimes are pointed out.

  2. Reprint of : Scattering approach to scanning gate microscopy

    NASA Astrophysics Data System (ADS)

    Jalabert, Rodolfo A.; Weinmann, Dietmar

    2016-08-01

    We present a perturbative approach to the conductance change caused by a weakly invasive scattering potential in a two-dimensional electron gas. The resulting expressions are used to investigate the relationship between the conductance change measured in scanning gate microscopy as a function of the position of a scattering tip and local electronic quantities like the current density. We use a semiclassical approach to treat the case of a strong hard-wall scatterer in a half-plane facing a reflectionless channel. The resulting conductance change is consistent with the numerically calculated quantum conductance.

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

    PubMed

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

    2010-01-01

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

  4. Localized charge imaging with scanning Kelvin probe microscopy

    NASA Astrophysics Data System (ADS)

    Orihuela, M. F.; Somoza, A. M.; Colchero, J.; Ortuño, M.; Palacios-Lidón, E.

    2017-01-01

    In this work, we propose an intuitive and easily implementable approach to model and interpret scanning Kelvin probe microscopy images of insulating samples with localized charges. The method, based on the image charges method, has been validated by a systematic comparison of its predictions with experimental measurements performed on charge domains of different sizes, injected in polymethyl methacrylate discontinuous films. The agreement between predictions and experimental lateral profiles, as well as with spectroscopy tip-sample distance curves, supports its consistency. The proposed procedure allows obtaining quantitative information such as total charge and the size of a charge domain and allows estimating the most adequate measurement parameters.

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

    PubMed

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

    2008-11-25

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

  6. Vectorial scanning force microscopy using a nanowire sensor

    NASA Astrophysics Data System (ADS)

    Rossi, Nicola; Braakman, Floris R.; Cadeddu, Davide; Vasyukov, Denis; Tütüncüoglu, Gözde; Fontcuberta I Morral, Anna; Poggio, Martino

    2016-10-01

    Self-assembled nanowire (NW) crystals can be grown into nearly defect-free nanomechanical resonators with exceptional properties, including small motional mass, high resonant frequency and low dissipation. Furthermore, by virtue of slight asymmetries in geometry, a NW's flexural modes are split into doublets oscillating along orthogonal axes. These characteristics make bottom-up grown NWs extremely sensitive vectorial force sensors. Here, taking advantage of its adaptability as a scanning probe, we use a single NW to image a sample surface. By monitoring the frequency shift and direction of oscillation of both modes as we scan above the surface, we construct a map of all spatial tip-sample force derivatives in the plane. Finally, we use the NW to image electric force fields distinguishing between forces arising from the NW charge and polarizability. This universally applicable technique enables a form of atomic force microscopy particularly suited to mapping the size and direction of weak tip-sample forces.

  7. Fast frame scanning camera system for light-sheet microscopy.

    PubMed

    Wu, Di; Zhou, Xing; Yao, Baoli; Li, Runze; Yang, Yanlong; Peng, Tong; Lei, Ming; Dan, Dan; Ye, Tong

    2015-10-10

    In the interest of improving the temporal resolution for light-sheet microscopy, we designed a fast frame scanning camera system that incorporated a galvanometer scanning mirror into the imaging path of a home-built light-sheet microscope. This system transformed a temporal image sequence to a spatial one so that multiple images could be acquired during one exposure period. The improvement factor of the frame rate was dependent on the number of sub-images that could be tiled on the sensor without overlapping each other and was therefore a trade-off with the image size. As a demonstration, we achieved 960 frames/s (fps) on a CCD camera that was originally capable of recording images at only 30 fps (full frame). This allowed us to observe millisecond or sub-millisecond events with ordinary CCD cameras.

  8. 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.

  9. Band Excitation in Scanning Probe Microscopy: Recognition and Functional Imaging

    NASA Astrophysics Data System (ADS)

    Jesse, S.; Vasudevan, R. K.; Collins, L.; Strelcov, E.; Okatan, M. B.; Belianinov, A.; Baddorf, A. P.; Proksch, R.; Kalinin, S. V.

    2014-04-01

    Field confinement at the junction between a biased scanning probe microscope's tip and solid surface enables local probing of various bias-induced transformations, such as polarization switching, ionic motion, and electrochemical reactions. The nanoscale size of the biased region, smaller or comparable to that of features such as grain boundaries and dislocations, potentially allows for the study of kinetics and thermodynamics at the level of a single defect. In contrast to classical statistically averaged approaches, this approach allows one to link structure to functionality and deterministically decipher associated mesoscopic and atomistic mechanisms. Furthermore, responses measured as a function of frequency and bias can serve as a fingerprint of local material functionality, allowing for local recognition imaging of inorganic and biological systems. This article reviews current progress in multidimensional scanning probe microscopy techniques based on band excitation time and voltage spectroscopies, including discussions on data acquisition, dimensionality reduction, and visualization, along with future challenges and opportunities for the field.

  10. Multifrequency scanning probe microscopy study of nanodiamond agglomerates

    NASA Astrophysics Data System (ADS)

    Aravind, Vasudeva; Lippold, Stephen; Li, Qian; Strelcov, Evgheny; Okatan, Baris; Legum, Benjamin; Kalinin, Sergei; Clarion University Team; Oak Ridge National Laboratory Team

    Due to their rich surface chemistry and excellent mechanical properties and non-toxic nature, nanodiamond particles have found applications such as biomedicine, tribology and lubrication, targeted drug delivery systems, tissue scaffolds and surgical implants. Although single nanodiamond particles have diameters about 4-5nm, they tend to form agglomerates. While these agglomerates can be useful for some purposes, many applications of nanodiamonds require single particle, disaggregated nanodiamonds. This work is oriented towards studying forces and interactions that contribute to agglomeration in nanodiamonds. In this work, using multifrequency scanning probe microscopy techniques, we show that agglomerate sizes can vary between 50-100nm in raw nanodiamonds. Extremeties of particles and Interfaces between agglomerates show dissipative forces with scanning probe microscope tip, indicating agglomerates could act as points of increased adhesion, thus reducing lubricating efficiency when nanodiamonds are used as lubricant additives. This research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

  11. Scanning SQUID microscopy with single electron spin sensitivity

    NASA Astrophysics Data System (ADS)

    Vasyukov, Denis

    2014-03-01

    Superconducting interference devices (SQUIDs) have been traditionally used for studying fundamental properties of magnetic materials and superconductors. Although widely used in scanning magnetic microscopy, their progress towards detection of small magnetic moments was stagnating of late due to limitations imposed by conventional designs of planar SQUIDs and contemporary lithography techniques, restricting sample-to-sensor distance smaller than ~ 0.5 micron and SQUIDs diameters smaller than ~ 200 nm. These limitations were overcome by the invention of a SQUID-on-tip device, subsequent realization of a SQUID-on-tip microscope, and by creation of an ultra-small sensor with spatial resolution of 20 nm and sensitivity to a single electron spin per 1 Hz bandwidth. In this talk I will describe the principles of scanning SQUID magnetometry, its applications to study superconductors and its potential for magnetic nano-scale imaging of novel materials.

  12. Point-spread function synthesis in scanning holographic microscopy

    PubMed Central

    Indebetouw, Guy; Zhong, Wenwei; Chamberlin-Long, David

    2006-01-01

    Scanning holographic microscopy is a two-pupil synthesis method allowing the capture of single-sideband inline holograms of noncoherent (e.g., fluorescent) three-dimensional specimens in a single two-dimensional scan. The flexibility offered by the two-pupil method in synthesizing unusual point-spread functions is discussed. We illustrate and compare three examples of holographic recording, using computer simulations. The first example is the classical hologram in which each object point is encoded as a spherical wave. The second example uses pupils with spherical phase distributions having opposite curvatures, leading to reconstructed images with a resolution limit that is half that of the objective. In the third example, axicon pupils are used to obtain axially sectioned images. PMID:16783435

  13. The relevance of electrostatics for scanning-gate microscopy

    NASA Astrophysics Data System (ADS)

    Schnez, S.; Güttinger, J.; Stampfer, C.; Ensslin, K.; Ihn, T.

    2011-05-01

    Scanning-probe techniques have been developed to extract local information from a given physical system. In particular, conductance maps obtained by means of scanning-gate microscopy (SGM), where a conducting tip of an atomic-force microscope is used as a local and movable gate, seem to present an intuitive picture of the underlying physical processes. Here, we argue that the interpretation of such images is complex and not very intuitive under certain circumstances: scanning a graphene quantum dot (QD) in the Coulomb-blockaded regime, we observe an apparent shift of features in scanning-gate images as a function of gate voltages, which cannot be a real shift of the physical system. Furthermore, we demonstrate the appearance of more than one set of Coulomb rings arising from the graphene QD. We attribute these effects to screening between the metallic tip and the gates. Our results are relevant for SGM on any kind of nanostructure, but are of particular importance for nanostructures that are not covered with a dielectric, e.g. graphene or carbon nanotube structures.

  14. High-speed multiresolution scanning probe microscopy based on Lissajous scan trajectories.

    PubMed

    Tuma, Tomas; Lygeros, John; Kartik, V; Sebastian, Abu; Pantazi, Angeliki

    2012-05-11

    A novel scan trajectory for high-speed scanning probe microscopy is presented in which the probe follows a two-dimensional Lissajous pattern. The Lissajous pattern is generated by actuating the scanner with two single-tone harmonic waveforms of constant frequency and amplitude. Owing to the extremely narrow frequency spectrum, high imaging speeds can be achieved without exciting the unwanted resonant modes of the scanner and without increasing the sensitivity of the feedback loop to the measurement noise. The trajectory also enables rapid multiresolution imaging, providing a preview of the scanned area in a fraction of the overall scan time. We present a procedure for tuning the spatial and the temporal resolution of Lissajous trajectories and show experimental results obtained on a custom-built atomic force microscope (AFM). Real-time AFM imaging with a frame rate of 1 frame s⁻¹ is demonstrated.

  15. Correlative analysis of immunoreactivity in confocal laser-scanning microscopy and scanning electron microscopy with focused ion beam milling.

    PubMed

    Sonomura, Takahiro; Furuta, Takahiro; Nakatani, Ikuko; Yamamoto, Yo; Unzai, Tomo; Matsuda, Wakoto; Iwai, Haruki; Yamanaka, Atsushi; Uemura, Masanori; Kaneko, Takeshi

    2013-01-01

    Recently, three-dimensional reconstruction of ultrastructure of the brain has been realized with minimal effort by using scanning electron microscopy (SEM) combined with focused ion beam (FIB) milling (FIB-SEM). Application of immunohistochemical staining in electron microscopy (EM) provides a great advantage in that molecules of interest are specifically localized in ultrastructures. Thus, we applied immunocytochemistry for FIB-SEM and correlated this immunoreactivity with that in confocal laser-scanning microcopy (CF-LSM). Dendrites of medium-sized spiny neurons in the rat neostriatum were visualized using a recombinant viral vector, which labeled the infected neurons with membrane-targeted GFP in a Golgi stain-like fashion. Moreover, the thalamostriatal afferent terminals were immunolabeled with Cy5 fluorescence for vesicular glutamate transporter 2 (VGluT2). After detection of the sites of terminals apposed to the dendrites by using CF-LSM, GFP and VGluT2 immunoreactivities were further developed for EM by using immunogold/silver enhancement and immunoperoxidase/diaminobenzidine (DAB) methods, respectively. In contrast-inverted FIB-SEM images, silver precipitations and DAB deposits were observed as fine dark grains and diffuse dense profiles, respectively, indicating that these immunoreactivities were as easily recognizable as those in the transmission electron microscopy (TEM) images. Furthermore, in the sites of interest, some appositions displayed synaptic specializations of an asymmetric type. Thus, the present method was useful in the three-dimensional analysis of immunocytochemically differentiated synaptic connections in the central neural circuit.

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

    PubMed

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

    2017-01-25

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  18. A new scanning mode to improve scanning ion conductance microscopy imaging rate with pipette predicted movement.

    PubMed

    Zhuang, Jian; Jiao, Yangbohan; Mugabo, Vincent

    2017-10-01

    Scanning ion conductance microscopy (SICM) is a non-contact surface topography measurement technique that has been increasingly used for soft surfaces such as living biological samples. An approach-retract scanning (ARS) mode is widely used to avoid collision between the SICM probe (i.e., pipette) and an abrupt increase in sample profile. However, the redundant pipette trajectory in the ARS mode lengthens the scan time, thus reducing SICM efficiency and time resolution. To avoid this problem, a new scanning mode is discussed that adds horizontal movement at each measurement point to predict the upcoming sample topography via variation in ion current. The pipette then retracts in response to raised topography, while it raster scans flat or downhill topography. The feasibility was verified by finite element analysis and experimental tests on three kinds of soft samples: polydimethylsiloxane, mice cardiac fibroblasts, and breast cancer cells. The pixel detection frequency during imaging and the mean square error of the sample topography were compared for the two modes. The new scanning mode enhances the SICM imaging rate without loss of imaging quality or scanning stability, while it increases efficiency and time resolution. It thus has an improved performance for characterizing biological samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  20. Biophysical Applications of Scanning Ion Conductance Microscopy (sicm)

    NASA Astrophysics Data System (ADS)

    Anariba, Franklin; Anh, Joon Hyung; Jung, Goo-Eun; Cho, Nam-Joon; Cho, Sang-Joon

    Scanning probe microscopy (SPM) techniques represent one of the most promising approaches to probe the physical and chemical properties of nanoscale materials. The growing convergence of physics and biology has demanded nanotechnology tools to understand the fundamental physics of biological systems. Despite the advantages of SPM techniques, there have been challenges with its application to characterization of biological specimens. In recent times, the development of one class of SPM technique, scanning ion conductance microscopy (SICM), has overcome these limitations and enabled noninvasive, nanoscale investigation of live cells. In this review article, we present the theory behind the SICM operating principles and data modeling. Based on this framework, we discuss recent research advances where the SICM technique has proven technically superior. SICM applications discussed herein include imaging of cell topography, monitoring of live cell dynamics, mechanical stimulation of live cells, and surface patterning. Additional findings on the combination of SICM with other SPM techniques as well as patch clamp electrophysiology are presented in the context of building integrated knowledge on the structure and function of live cells. In summary, SICM bridges physics and biology to enable a range of important biomedical applications.

  1. Nanoscale cellular imaging with scanning angle interference microscopy.

    PubMed

    DuFort, Christopher; Paszek, Matthew

    2014-01-01

    Fluorescence microscopy is among the most widely utilized tools in cell and molecular biology due to its ability to noninvasively obtain time-resolved images of live cells with molecule-specific contrast. In this chapter, we describe a simple high-resolution technique, scanning angle interference microscopy (SAIM), for the imaging and localization of fluorescent molecules with nanometer precision along the optical axis. In SAIM, samples above a reflective surface are sequentially scanned with an excitation laser at varying angles of incidence. Interference patterns generated between the incident and reflected lights result in an emission intensity that depends on the height of a fluorophore above the silicon surface and the angle of the incident radiation. The measured fluorescence intensities are then fit to an optical model to localize the labeled molecules along the z-axis with 5-10 nm precision and diffraction-limited lateral resolution. SAIM is easily implemented on widely available commercial total internal reflection fluorescence microscopes, offering potential for widespread use in cell biology. Here, we describe the setup of SAIM and its application for imaging cellular structures near (<1 μm) the sample substrate. © 2014 Elsevier Inc. All rights reserved.

  2. Microscale friction investigation of polysilicon surface using scanning force microscopy

    NASA Astrophysics Data System (ADS)

    Flueraru, C.; Cobianu, C.; Dascalu, D.; Flueraru, M.

    1998-07-01

    Microscale phenomena between the surface of chemically vapour deposited silicon films and a silicon nitride tip was investigated using Scanning Force Microscopy. An analysis of friction forces for different scan directions is presented. For different applied forces, the friction forces were measured and consequently the friction coefficient was calculated. We found that the average friction force linearly increases with the applied force and is reversible when unloading. Connection between the surface roughness and the friction coefficient was experimentally demonstrated. On a étudié par Microscopie à Force Atomique des phénomènes à échelle microscopique au niveau de la jonction pointe de nitrure de silicium et surface de films de silicium, obtenus par déposition chimique en phase vapeur. Dans cet article, nous présentons une analyse des forces de friction pour différentes directions de balayage. On a déterminé les forces de friction et, en conséquence, nous avons calculé le coefficient de friction pour différentes forces appliquées. Les résultats montrent que la force moyenne de friction augmente en fonction de la force appliquée, et qu'elle est reversible lorsque la charge diminue. Une dépendance entre la rugosité de la surface et le coefficient de friction est déduite.

  3. High-resolution imaging by scanning electron microscopy of semithin sections in correlation with light microscopy.

    PubMed

    Koga, Daisuke; Kusumi, Satoshi; Shodo, Ryusuke; Dan, Yukari; Ushiki, Tatsuo

    2015-12-01

    In this study, we introduce scanning electron microscopy (SEM) of semithin resin sections. In this technique, semithin sections were adhered on glass slides, stained with both uranyl acetate and lead citrate, and observed with a backscattered electron detector at a low accelerating voltage. As the specimens are stained in the same manner as conventional transmission electron microscopy (TEM), the contrast of SEM images of semithin sections was similar to TEM images of ultrathin sections. Using this technique, wide areas of semithin sections were also observed by SEM, without the obstruction of grids, which was inevitable for traditional TEM. This study also applied semithin section SEM to correlative light and electron microscopy. Correlative immunofluorescence microscopy and immune-SEM were performed in semithin sections of LR white resin-embedded specimens using a FluoroNanogold-labeled secondary antibody. Because LR white resin is hydrophilic and electron stable, this resin is suitable for immunostaining and SEM observation. Using correlative microscopy, the precise localization of the primary antibody was demonstrated by fluorescence microscopy and SEM. This method has great potential for studies examining the precise localization of molecules, including Golgi- and ER-associated proteins, in correlation with LM and SEM.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  6. In-situ scanning probe microscopy of electrodeposited nickel.

    SciTech Connect

    Kelly, James J.; Dibble, Dean C.

    2004-10-01

    The performance characteristics and material properties such as stress, microstructure, and composition of nickel coatings and electroformed components can be controlled over a wide range by the addition of small amounts of surface-active compounds to the electroplating bath. Saccharin is one compound that is widely utilized for its ability to reduce tensile stress and refine grain size in electrodeposited nickel. While the effects of saccharin on nickel electrodeposition have been studied by many authors in the past, there is still uncertainty over saccharin's mechanisms of incorporation, stress reduction, and grain refinement. In-situ scanning probe microscopy (SPM) is a tool that can be used to directly image the nucleation and growth of thin nickel films at nanometer length scales to help elucidate saccharin's role in the development and evolution of grain structure. In this study, in-situ atomic force microscopy (AFM) and scanning tunneling microscopy (STM) techniques are used to investigate the effects of saccharin on the morphological evolution of thin nickel films. By observing mono-atomic height nickel island growth with and without saccharin present we conclude that saccharin has little effect on the nickel surface mobility during deposition at low overpotentials where the growth occurs in a layer-by-layer mode. Saccharin was imaged on Au(l11) terraces as condensed patches without resolved packing structure. AFM measurements of the roughness evolution of nickel films up to 1200 nm thick on polycrystalline gold indicate that saccharin initially increases the roughness and surface skewness of the deposit that at greater thickness becomes smoother than films deposited without saccharin. Faceting of the deposit morphology decreases as saccharin concentration increases even for the thinnest films that have 3-D growth.

  7. Resolving 2D Amorphous Materials with Scanning Probe Microscopy

    NASA Astrophysics Data System (ADS)

    Burson, Kristen M.; Buechner, Christin; Lewandowski, Adrian; Heyde, Markus; Freund, Hans-Joachim

    Novel two-dimensional (2D) materials have garnered significant scientific interest due to their potential technological applications. Alongside the emphasis on crystalline materials, such as graphene and hexagonal BN, a new class of 2D amorphous materials must be pursued. For amorphous materials, a detailed understanding of the complex structure is necessary. Here we present a structural study of 2D bilayer silica on Ru(0001), an insulating material which is weakly coupled to the substrate. Atomic structure has been determined with a dual mode atomic force microscopy (AFM) and scanning tunneling microscopy (STM) sensor in ultra-high vacuum (UHV) at low temperatures, revealing a network of different ring sizes. Liquid AFM measurements with sub-nanometer resolution bridge the gap between clean UHV conditions and the environments that many material applications demand. Samples are grown and characterized in vacuum and subsequently transferred to the liquid AFM. Notably, the key structural features observed, namely nanoscale ring networks and larger holes to the substrate, show strong quantitative agreement between the liquid and UHV microscopy measurements. This provides direct evidence for the structural stability of these silica films for nanoelectronics and other applications. KMB acknowledges support from the Alexander von Humboldt Foundation.

  8. Characterization of human breast cancer by scanning acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Di; Malyarenko, Eugene; Seviaryn, Fedar; Yuan, Ye; Sherman, Mark; Bandyopadhyay, Sudeshna; Gierach, Gretchen; Greenway, Christopher W.; Maeva, Elena; Strumban, Emil; Duric, Neb; Maev, Roman

    2013-03-01

    Objectives: The purpose of this study was to characterize human breast cancer tissues by the measurement of microacoustic properties. Methods: We investigated eight breast cancer patients using acoustic microscopy. For each patient, seven blocks of tumor tissue were collected from seven different positions around a tumor mass. Frozen sections (10 micrometer, μm) of human breast cancer tissues without staining and fixation were examined in a scanning acoustic microscope with focused transducers at 80 and 200 MHz. Hematoxylin and Eosin (H and E) stained sections from the same frozen breast cancer tissues were imaged by optical microscopy for comparison. Results: The results of acoustic imaging showed that acoustic attenuation and sound speed in cancer cell-rich tissue regions were significantly decreased compared with the surrounding tissue regions, where most components are normal cells/tissues, such as fibroblasts, connective tissue and lymphocytes. Our observation also showed that the ultrasonic properties were influenced by arrangements of cells and tissue patterns. Conclusions: Our data demonstrate that attenuation and sound speed imaging can provide biomechanical information of the tumor and normal tissues. The results also demonstrate the potential of acoustic microscopy as an auxiliary method for operative detection and localization of cancer affected regions.

  9. Confocal laser scanning microscopy in study of bone calcification

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  10. Extracting twins from orientation imaging microscopy scan data.

    PubMed

    Wright, S I; Larsen, R J

    2002-03-01

    Automated electron backscatter diffraction or orientation imaging microscopy (OIM) provides spatially specific measurements of crystallographic orientation. These measurements are typically collected on regular grids. By inspecting the misorientation between neighbouring measurements on the grid, potential twin boundaries can be identified. If the misorientation is within some given tolerance of a specified twin misorientation, the boundary separating the two measurements may be identified as a potential twin boundary. In addition, for a coherent twin, the twinning planes must be coincident with the grain boundary plane. As OIM scans are inherently two-dimensional, the scan data provide only limited information on the boundary plane. Thus, it is not possible to ascertain definitively whether the twinning planes are coincident with the boundary plane. Nonetheless, the alignment of the surface traces of the twinning planes with the trace of the boundary provides a partial indication of coincidence. An automated approach has been developed that allows data concerning both twin criterion to be extracted from OIM scans. Application of the methodology to deformed zirconium suggests that the twinning planes remain coherent during deformation. The methodology was also used to improve grain size distributions measured by OIM. These results more closely match those obtained by conventional metallography.

  11. Antecedents of two-photon excitation laser scanning microscopy.

    PubMed

    Masters, Barry R; So, Peter T C

    2004-01-01

    In 1931, Maria Göppert-Mayer published her doctoral dissertation on the theory of two-photon quantum transitions (two-photon absorption and emission) in atoms. This report describes and analyzes the theoretical and experimental work on nonlinear optics, in particular two-photon excitation processes, that occurred between 1931 and the experimental implementation of two-photon excitation microscopy by the group of Webb in 1990. In addition to Maria Göppert-Mayer's theoretical work, the invention of the laser has a key role in the development of two-photon microscopy. Nonlinear effects were previously observed in different frequency domains (low-frequency electric and magnetic fields and magnetization), but the high electric field strength afforded by lasers was necessary to demonstrate many nonlinear effects in the optical frequency range. In 1978, the first high-resolution nonlinear microscope with depth resolution was described by the Oxford group. Sheppard and Kompfner published a study in Applied Optics describing microscopic imaging based on second-harmonic generation. In their report, they further proposed that other nonlinear optical effects, such as two-photon fluorescence, could also be applied. However, the developments in the field of nonlinear optical stalled due to a lack of a suitable laser source. This obstacle was removed with the advent of femtosecond lasers in the 1980s. In 1990, the seminal study of Denk, Strickler, and Webb on two-photon laser scanning fluorescence microscopy was published in Science. Their paper clearly demonstrated the capability of two-photon excitation microscopy for biology, and it served to convince a wide audience of scientists of the potential capability of the technique.

  12. Three-dimensional optical sectioning by scanning confocal electron microscopy with a stage-scanning system.

    PubMed

    Hashimoto, Ayako; Shimojo, Masayuki; Mitsuishi, Kazutaka; Takeguchi, Masaki

    2010-06-01

    We evaluated the depth resolution of annular dark-field (ADF) scanning confocal electron microscopy (SCEM) with a stage-scanning system by observation of nanoparticles. ADF-SCEM is a three-dimensional (3D) imaging technique that we recently proposed. An ADF-SCEM instrument involves a pinhole aperture before a detector for rejecting electrons from the out-of-focal plane in a specimen and an annular aperture under the specimen for collecting only scattered electrons. The stage-scanning system enables us to directly obtain optical slice images perpendicular and parallel to an optical axis at a desired position. In particular, the parallel slices visualize the elongation of nanoparticles along the optical axis, which depends on the depth resolution. ADF-SCEM effectively reduced the elongation length of the nanoparticles sufficiently to demonstrate depth sectioning, in comparison with scanning transmission electron microscopy and bright-field SCEM. The experimentally obtained length was nearly equal to the theoretically estimated one from the probe size considering the experimental conditions. Furthermore, we applied this ADF-SCEM technique to analysis of the 3D position of catalytic nanoparticles on carbon nanostructures.

  13. Characterization of two-dimensional hexagonal boron nitride using scanning electron and scanning helium ion microscopy

    SciTech Connect

    Guo, Hongxuan E-mail: msxu@zju.edu.cn; Gao, Jianhua; Ishida, Nobuyuki; Xu, Mingsheng E-mail: msxu@zju.edu.cn; Fujita, Daisuke

    2014-01-20

    Characterization of the structural and physical properties of two-dimensional (2D) materials, such as layer number and inelastic mean free path measurements, is very important to optimize their synthesis and application. In this study, we characterize the layer number and morphology of hexagonal boron nitride (h-BN) nanosheets on a metallic substrate using field emission scanning electron microscopy (FE-SEM) and scanning helium ion microscopy (HIM). Using scanning beams of various energies, we could analyze the dependence of the intensities of secondary electrons on the thickness of the h-BN nanosheets. Based on the interaction between the scanning particles (electrons and helium ions) and h-BN nanosheets, we deduced an exponential relationship between the intensities of secondary electrons and number of layers of h-BN. With the attenuation factor of the exponential formula, we calculate the inelastic mean free path of electrons and helium ions in the h-BN nanosheets. Our results show that HIM is more sensitive and consistent than FE-SEM for characterizing the number of layers and morphology of 2D materials.

  14. Characterization of two-dimensional hexagonal boron nitride using scanning electron and scanning helium ion microscopy

    NASA Astrophysics Data System (ADS)

    Guo, Hongxuan; Gao, Jianhua; Ishida, Nobuyuki; Xu, Mingsheng; Fujita, Daisuke

    2014-01-01

    Characterization of the structural and physical properties of two-dimensional (2D) materials, such as layer number and inelastic mean free path measurements, is very important to optimize their synthesis and application. In this study, we characterize the layer number and morphology of hexagonal boron nitride (h-BN) nanosheets on a metallic substrate using field emission scanning electron microscopy (FE-SEM) and scanning helium ion microscopy (HIM). Using scanning beams of various energies, we could analyze the dependence of the intensities of secondary electrons on the thickness of the h-BN nanosheets. Based on the interaction between the scanning particles (electrons and helium ions) and h-BN nanosheets, we deduced an exponential relationship between the intensities of secondary electrons and number of layers of h-BN. With the attenuation factor of the exponential formula, we calculate the inelastic mean free path of electrons and helium ions in the h-BN nanosheets. Our results show that HIM is more sensitive and consistent than FE-SEM for characterizing the number of layers and morphology of 2D materials.

  15. Laser-scanning photoacoustic microscopy with ultrasonic phased array transducer.

    PubMed

    Zheng, Fan; Zhang, Xiangyang; Chiu, Chi Tat; Zhou, Bill L; Shung, K Kirk; Zhang, Hao F; Jiao, Shuliang

    2012-11-01

    In this paper, we report our latest progress on proving the concept that ultrasonic phased array can improve the detection sensitivity and field of view (FOV) in laser-scanning photoacoustic microscopy (LS-PAM). A LS-PAM system with a one-dimensional (1D) ultrasonic phased array was built for the experiments. The 1D phased array transducer consists of 64 active elements with an overall active dimension of 3.2 mm × 2 mm. The system was tested on imaging phantom and mouse ear in vivo. Experiments showed a 15 dB increase of the signal-to-noise ratio (SNR) when beamforming was employed compared to the images acquired with each single element. The experimental results demonstrated that ultrasonic phased array can be a better candidate for LS-PAM in high sensitivity applications like ophthalmic imaging.

  16. Combined Scanning Transmission Electron Microscopy Tilt- and Focal Series

    SciTech Connect

    Dahmen, Tim; Baudoin, Jean-Pierre G; Lupini, Andrew R; Kubel, Christian; Slusallek, Phillip; De Jonge, Niels

    2014-01-01

    In this study, a combined tilt- and focal series is proposed as a new recording scheme for high-angle annular dark-field scanning transmission electron microscopy (STEM) tomography. Three-dimensional (3D) data were acquired by mechanically tilting the specimen, and recording a through-focal series at each tilt direction. The sample was a whole-mount macrophage cell with embedded gold nanoparticles. The tilt focal algebraic reconstruction technique (TF-ART) is introduced as a new algorithm to reconstruct tomograms from such combined tilt- and focal series. The feasibility of TF-ART was demonstrated by 3D reconstruction of the experimental 3D data. The results were compared with a conventional STEM tilt series of a similar sample. The combined tilt- and focal series led to smaller missing wedge artifacts, and a higher axial resolution than obtained for the STEM tilt series, thus improving on one of the main issues of tilt series-based electron tomography.

  17. Scanning electrochemical microscopy of Li-ion batteries.

    PubMed

    Ventosa, E; Schuhmann, W

    2015-11-21

    Li-ion batteries (LIBs) are receiving increasing attention over the past decade due to their high energy density. This energy storage technology is expected to continue improving the performance, especially for its large-scale deployment in plug-in hybrid electric vehicles (PHEVs) and full electric vehicles (EVs). Such improvement requires having a large variety of analytical techniques at scientists' disposal in order to understand and address the multiple mechanisms and processes occurring simultaneously in this complex system. This perspective article aims to highlight the strength and potential of scanning electrochemical microscopy (SECM) in this field. After a brief description of a LIB system and the most commonly used techniques in this field, the unique information provided by SECM is illustrated by discussing several recent examples from the literature.

  18. Microfluidic push-pull probe for scanning electrochemical microscopy.

    PubMed

    Momotenko, Dmitry; Cortes-Salazar, Fernando; Lesch, Andreas; Wittstock, Gunther; Girault, Hubert H

    2011-07-01

    This paper presents a microfluidic push-pull probe for scanning electrochemical microscopy (SECM) consisting of a working microelectrode, an integrated counter/reference electrode and two microchannels for pushing and pulling an electrolyte solution to and away from a substrate. With such a configuration, a droplet of a permanently renewed redox mediator solution is maintained just at the probe tip to carry out SECM measurements on initially dry substrates or in microenvironments. For SECM imaging purposes, the probe fabricated in a soft polymer material is used in a contact regime. SECM images of various gold-on-glass samples demonstrate the proof-of-concept of a push-pull probe for local surface activity characterization with high spatial resolution even on vertically oriented substrates. Finite element computations were performed to guide the improvement of the probe sensitivity.

  19. Quantitative flaw characterization with scanning laser acoustic microscopy

    SciTech Connect

    Generazio, E.R.; Roth, D.J.

    1986-06-01

    Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. Inaccuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw. 15 references.

  20. Quantitative flaw characterization with scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Generazio, E. R.; Roth, D. J.

    1986-01-01

    Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. Inaccuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw.

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

    PubMed

    Fedorov, Roman G; Mandler, Daniel

    2013-02-28

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

  2. Quantitative flaw characterization with scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Generazio, E. R.; Roth, D. J.

    1986-01-01

    Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. In accuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw.

  3. Scanning force microscopy reveals ellipsoid shape of chicken erythrocyte nucleosomes.

    PubMed Central

    Fritzsche, W; Henderson, E

    1996-01-01

    Scanning force microscopy was used to investigate the conformation of hypotonic spread chicken erythrocyte nucleosomes. Nucleosomal chains were prepared in low-salt conditions and fixed before centrifugation onto glass coverslips and air drying. The images of single nucleosomes were isolated by image processing, and the height and geometry of the resulting three-dimensional structures were investigated. An average nucleosome height of 4.2 +/- 1.1 nm was determined. A virtual cross section at half-maximum height of the nucleosome structure was used for a characterization of the nucleosome geometry. The shape of this cross section was best described by an ellipse with an aspect ratio (major/minor axis) of approximately 1.30. Images FIGURE 1 FIGURE 2 FIGURE 3 PMID:8889198

  4. Theory and application of scanning electron acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu; Chen, Ruiyi; Yost, William T.

    1992-01-01

    A three-dimensional theoretical model based on the application of the thermal conduction and Navier equations to a chopped electron beam incident on a disk specimen is used to obtain the particle displacement field in the specimen. The results lead to a consideration of the signal generation, spatial resolution, and contrast mechanisms in scanning electron acoustic microscopy (SEAM). The model suggests that the time-variant heat source produced by the beam chopping generates driving source, thermal wave, and acoustic wave displacements simultaneously in the specimen. Evidence of the correctness of the prediction is obtained from the mathematically similar problem of pulsed laser light injection into a tank of water. High speed Schlieren photographs taken following laser injection show the simultaneous evolution of thermal and acoustic waveforms. Examples of contrast reversal, stress-induced contrast, and acoustic zone contrast and resolution with SEAM are presented and explained in terms of the model features.

  5. Modeling atomic-resolution scanning transmission electron microscopy images.

    PubMed

    Findlay, Scott D; Oxley, Mark P; Allen, Leslie J

    2008-02-01

    A real-space description of inelastic scattering in scanning transmission electron microscopy is derived with particular attention given to the implementation of the projected potential approximation. A hierarchy of approximations to expressions for inelastic images is presented. Emphasis is placed on the conditions that must hold in each case. The expressions that justify the most direct, visual interpretation of experimental data are also the most approximate. Therefore, caution must be exercised in selecting experimental parameters that validate the approximations needed for the analysis technique used. To make the most direct, visual interpretation of electron-energy-loss spectroscopic images from core-shell excitations requires detector improvements commensurate with those that aberration correction provides for the probe-forming lens. Such conditions can be relaxed when detailed simulations are performed as part of the analysis of experimental data.

  6. Sample heating system for spin-polarized scanning electron microscopy.

    PubMed

    Kohashi, Teruo; Motai, Kumi

    2013-08-01

    A sample-heating system for spin-polarized scanning electron microscopy (spin SEM) has been developed and used for microscopic magnetization analysis at temperatures up to 500°C. In this system, a compact ceramic heater and a preheating operation keep the ultra-high vacuum conditions while the sample is heated during spin SEM measurement. Moreover, the secondary-electron collector, which is arranged close to the sample, was modified so that it is not damaged at high temperatures. The system was used to heat a Co(1000) single-crystal sample from room temperature up to 500°C, and the magnetic-domain structures were observed. Changes of the domain structures were observed around 220 and 400°C, and these changes are considered to be due to phase transitions of this sample.

  7. Video-rate Scanning Confocal Microscopy and Microendoscopy

    PubMed Central

    Nichols, Alexander J.; Evans, Conor L.

    2011-01-01

    Confocal microscopy has become an invaluable tool in biology and the biomedical sciences, enabling rapid, high-sensitivity, and high-resolution optical sectioning of complex systems. Confocal microscopy is routinely used, for example, to study specific cellular targets1, monitor dynamics in living cells2-4, and visualize the three dimensional evolution of entire organisms5,6. Extensions of confocal imaging systems, such as confocal microendoscopes, allow for high-resolution imaging in vivo7 and are currently being applied to disease imaging and diagnosis in clinical settings8,9. Confocal microscopy provides three-dimensional resolution by creating so-called "optical sections" using straightforward geometrical optics. In a standard wide-field microscope, fluorescence generated from a sample is collected by an objective lens and relayed directly to a detector. While acceptable for imaging thin samples, thick samples become blurred by fluorescence generated above and below the objective focal plane. In contrast, confocal microscopy enables virtual, optical sectioning of samples, rejecting out-of-focus light to build high resolution three-dimensional representations of samples. Confocal microscopes achieve this feat by using a confocal aperture in the detection beam path. The fluorescence collected from a sample by the objective is relayed back through the scanning mirrors and through the primary dichroic mirror, a mirror carefully selected to reflect shorter wavelengths such as the laser excitation beam while passing the longer, Stokes-shifted fluorescence emission. This long-wavelength fluorescence signal is then passed to a pair of lenses on either side of a pinhole that is positioned at a plane exactly conjugate with the focal plane of the objective lens. Photons collected from the focal volume of the object are collimated by the objective lens and are focused by the confocal lenses through the pinhole. Fluorescence generated above or below the focal plane will

  8. Adaptive optics for confocal laser scanning microscopy with adjustable pinhole

    NASA Astrophysics Data System (ADS)

    Yoo, Han Woong; van Royen, Martin E.; van Cappellen, Wiggert A.; Houtsmuller, Adriaan B.; Verhaegen, Michel; Schitter, Georg

    2016-04-01

    The pinhole plays an important role in confocal laser scanning microscopy (CLSM) for adaptive optics (AO) as well as in imaging, where the size of the pinhole denotes a trade-off between out-of-focus rejection and wavefront distortion. This contribution proposes an AO system for a commercial CLSM with an adjustable square pinhole to cope with such a trade-off. The proposed adjustable pinhole enables to calibrate the AO system and to evaluate the imaging performance. Experimental results with fluorescence beads on the coverslip and at a depth of 40 μm in the human hepatocellular carcinoma cell spheroid demonstrate that the proposed AO system can improve the image quality by the proposed calibration method. The proposed pinhole intensity ratio also indicates the image improvement by the AO correction in intensity as well as resolution.

  9. Investigation of crossed SAW fields by scanning acoustic force microscopy.

    PubMed

    Behme, G; Hesjedal, T

    2001-07-01

    We used multimode scanning acoustic force microscopy (SAFM) for studying noncollinearly propagating Rayleigh and Love wave fields. By analyzing torsion and bending movement of SAFM cantilever, normal and in-plane wave oscillation components are accessible. The SAFM principle is the down-conversion of surface oscillations into cantilever vibrations caused by the nonlinearity of the tip-sample interaction. Through mixing of complementary oscillation components, phase velocities of crossed Rayleigh waves on GaAs and crossed Rayleigh and Love waves on the layered system SiO2/ST-cut quartz were obtained simultaneously. Now, it is possible to investigate elastic properties of submicron areas through multimode SAFM measurements. Finally, we present mixing experiments of four SAWs on GaAs and discuss the various influences on the measured SAFM amplitude and phase contrast.

  10. 2-photon laser scanning microscopy on native human cartilage

    NASA Astrophysics Data System (ADS)

    Martini, Joerg; Toensing, Katja; Dickob, Michael; Anselmetti, Dario

    2005-08-01

    Native hyaline cartilage from a human knee joint was directly investigated with laser scanning microscopy via 2-photon autofluorescence excitation with no additional staining or labelling protocols in a nondestructive and sterile manner. Using a femtosecond, near-infrared (NIR) Ti:Sa laser for 2-photon excitation and a dedicated NIR long distance objective, autofluorescence imaging and measurements of the extracellular matrix (ECM) tissue with incorporated chondrocytes were possible with a penetration depth of up to 460 μm inside the sample. Via spectral autofluorescence separation these experiments allowed the discrimination of chondrocytes from the ECM and therefore an estimate of chondrocytic cell density within the cartilage tissue to approximately 0.2-2•107cm3. Furthermore, a comparison of the relative autofluorescence signals between nonarthritic and arthritic cartilage tissue exhibited distinct differences in tissue morphology. As these morphological findings are in keeping with the macroscopic diagnosis, our measurement has the potential of being used in future diagnostic applications.

  11. Scanning photoelectron microscopy using a pointed capillary probe

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

    The possibilities of a new type of scanning probe microscopy (SPM) for two different samples are experimentally demonstrated. The method is based on the use of a pointed capillary, which can simultaneously act as a 'classical' SPM probe and also as a controlled thin channel for transporting charged particles emitted by the surface to the detector. In the experiment, photoelectrons pass through a dielectric hollow cone probe with an aperture radius of 1 μm and detected by microchannel plates at different points of the investigated conducting surface irradiated by the second harmonic of a femtosecond Ti : sapphire laser. As a result, the sample's surface profile is visualised with a subwavelength spatial resolution. This method makes it possible to control spatially localised beams of electrons, ions, neutral atoms (molecules) and soft X-ray radiation, as well as opens a possibility for research in the field of nanoscale photodesorption of molecular ions.

  12. Organic Multilayer Films Studied by Scanning Tunneling Microscopy.

    PubMed

    He, Yang; Kröger, Jörg; Wang, Yongfeng

    2017-03-03

    This Minireview focuses exclusively on work with scanning tunneling microscopy to study the self-assembled multilayer films (SAMTs) of organic molecules. The π-conjugated organic molecules form different structures within different monolayers on various substrates. The interplay between molecule-substrate and intermolecular interactions plays a key role in determining the stacking mode of organic multilayer films. Different substrates strongly influence the organic-film growth and electronic properties of the organic molecules. Geometric and electronic structures of SAMTs are important factors that may determine device performance. In addition to the inorganic interface, this Minireview addresses the organic-organic interface. Homo- and hetero-SAMTs of organic molecules are also considered. The subtle interplay between structural and electronic characteristics, on one hand, and functionality and reactivity, on the other hand, are highlighted.

  13. Theory and application of scanning electron acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu; Chen, Ruiyi; Yost, William T.

    1992-01-01

    A three-dimensional theoretical model based on the application of the thermal conduction and Navier equations to a chopped electron beam incident on a disk specimen is used to obtain the particle displacement field in the specimen. The results lead to a consideration of the signal generation, spatial resolution, and contrast mechanisms in scanning electron acoustic microscopy (SEAM). The model suggests that the time-variant heat source produced by the beam chopping generates driving source, thermal wave, and acoustic wave displacements simultaneously in the specimen. Evidence of the correctness of the prediction is obtained from the mathematically similar problem of pulsed laser light injection into a tank of water. High speed Schlieren photographs taken following laser injection show the simultaneous evolution of thermal and acoustic waveforms. Examples of contrast reversal, stress-induced contrast, and acoustic zone contrast and resolution with SEAM are presented and explained in terms of the model features.

  14. Flaw characterization in structural ceramics using scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Roth, Don J.

    1988-01-01

    The ability of scanning laser acoustic microscopy (SLAM) to characterize artifically seeded voids in sintered silicon nitride structural ceramic specimens was investigated. The voids ranged from 20 to 430 microns in diameter and were embedded up to 2 mm beneath the surface of the specimens. Probability of detection was determined as a function of void depth and size. Trigonometric relationships and Airy's diffraction theory were used to obtain predictions of void depth and size from acoustic diffraction patterns produced by the voids. Agreement was observed between actual and predicted void depths. However, predicted void diameters were generally much greater than actual diameters. Precise diameter predictions are difficult to obtain because of measurement uncertainty and the limitations of the 100 MHz SLAM applied to typical ceramic specimens.

  15. Microbial Nanowire Electronic Structure Probed by Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Veazey, Joshua P.; Lampa-Pastirk, Sanela; Reguera, Gemma; Tessmer, Stuart H.

    2010-03-01

    Complex molecules produced by living organisms provide laboratories for interesting physical properties. The study of such interesting physics, likewise, gives new insight into intriguing biological processes. We have studied the pilus nanowires expressed by the bacterium, Geobacter sulfurreducens, using high resolution scanning tunneling microscopy (STM). G. sulfurreducens is a metal reducing bacterium that has evolved electrically conductive pili to efficiently transfer electrons across large distances.footnotetextG. Reguera, K.D. McCarthy, T. Mehta, J.S. Nicoll, M.T. Tuominen, and D.R. Lovley, Nature 435, 1098 (2005) Here we employ the electronic sensitivity of STM to resolve the molecular substructure and the local electronic density of states (LDOS) along the nanowire, in an effort to elucidate the mechanism of conduction. We observe LDOS dependent upon the location of the tip above the nanowire.

  16. Laser-scanning photoacoustic microscopy with ultrasonic phased array transducer

    PubMed Central

    Zheng, Fan; Zhang, Xiangyang; Chiu, Chi Tat; Zhou, Bill L.; Shung, K. Kirk; Zhang, Hao F.; Jiao, Shuliang

    2012-01-01

    In this paper, we report our latest progress on proving the concept that ultrasonic phased array can improve the detection sensitivity and field of view (FOV) in laser-scanning photoacoustic microscopy (LS-PAM). A LS-PAM system with a one-dimensional (1D) ultrasonic phased array was built for the experiments. The 1D phased array transducer consists of 64 active elements with an overall active dimension of 3.2 mm × 2 mm. The system was tested on imaging phantom and mouse ear in vivo. Experiments showed a 15 dB increase of the signal-to-noise ratio (SNR) when beamforming was employed compared to the images acquired with each single element. The experimental results demonstrated that ultrasonic phased array can be a better candidate for LS-PAM in high sensitivity applications like ophthalmic imaging. PMID:23162708

  17. Fabrication of monolithic diamond probes for scanning probe microscopy applications

    NASA Astrophysics Data System (ADS)

    Scholz, Wenzel; Albert, D.; Malave, A.; Werner, Stephfan; Mihalcea, Christopher; Kulisch, Wilhelm; Oesterschulze, Egbert

    1997-04-01

    A process relying on the molding technique for the fabrication of diamond cantilevers with diamond tips integrated on silicon wafers for scanning probe microscopy applications is described. Either hot filament or microwave CVD diamond deposition and standard techniques of silicon micro-machining are employed. The deposition of well- developed tips depends critically on the pretreatment applied to enhance nucleation density; abrasive treatment with diamond powder as well as the bias-enhanced nucleation turned out to be successful. With optimized processes, well- shaped tips with a radius of curvature in the order of 30 nm can be obtained. They consist of high quality diamond according to micro-Raman spectroscopy. The definition of the cantilever area is another critical step which can be solved by proper process design. The fabrication of conductive tips/cantilevers is possible by boron doping. Finally, first performance tests of the diamond tips and cantilevers are presented.

  18. Scanning capacitance microscopy on ultranarrow doping profiles in Si

    NASA Astrophysics Data System (ADS)

    Giannazzo, F.; Goghero, D.; Raineri, V.; Mirabella, S.; Priolo, F.

    2003-09-01

    Scanning capacitance microscopy (SCM) has been performed both in cross-sectional and in angle-beveling configurations on ultranarrow B spikes with a full width at half-maximum smaller than the SCM probe diameter. The dependence of the SCM response on the magnification factor has been studied, demonstrating an improvement both in terms of spatial resolution and sensitivity by angle-beveling sample preparation. The range of applicability of the direct inversion approach for the quantification of SCM profiles on ultranarrow B spikes has been assessed for high doping spikes thicker than 3 nm and measured on bevel. Two-dimensional simulations allowed the reproduction of all the main features of the experimental SCM profiles.

  19. Adaptive optics two-photon scanning laser fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Zhou, Yaopeng; Bifano, Thomas; Lin, Charles

    2011-03-01

    Two-photon fluorescence microscopy provides a powerful tool for deep tissue imaging. However, optical aberrations from illumination beam path limit imaging depth and resolution. Adaptive Optics (AO) is found to be useful to compensate for optical aberrations and improve image resolution and contrast from two-photon excitation. We have developed an AO system relying on a MEMS Deformable Mirror (DM) to compensate the optical aberrations in a two-photon scanning laser fluorescence microscope. The AO system utilized a Zernike polynomial based stochastic parallel gradient descent (SPGD) algorithm to optimize the DM shape for wavefront correction. The developed microscope is applied for subsurface imaging of mouse bone marrow. It was demonstrated that AO allows 80% increase in fluorescence signal intensity from bone cavities 145um below the surface. The AO-enhanced microscope provides cellular level images of mouse bone marrow at depths exceeding those achievable without AO.

  20. Effects of instrument imperfections on quantitative scanning transmission electron microscopy.

    PubMed

    Krause, Florian F; Schowalter, Marco; Grieb, Tim; Müller-Caspary, Knut; Mehrtens, Thorsten; Rosenauer, Andreas

    2016-02-01

    Several instrumental imperfections of transmission electron microscopes are characterized and their effects on the results of quantitative scanning electron microscopy (STEM) are investigated and quantified using simulations. Methods to either avoid influences of these imperfections during acquisition or to include them in reference calculations are proposed. Particularly, distortions inflicted on the diffraction pattern by an image-aberration corrector can cause severe errors of more than 20% if not accounted for. A procedure for their measurement is proposed here. Furthermore, afterglow phenomena and nonlinear behavior of the detector itself can lead to incorrect normalization of measured intensities. Single electrons accidentally impinging on the detector are another source of error but can also be exploited for threshold-less calibration of STEM images to absolute dose, incident beam current determination and measurement of the detector sensitivity. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Thermal mapping of a scanning thermal microscopy tip.

    PubMed

    Jóźwiak, Grzegorz; Wielgoszewski, Grzegorz; Gotszalk, Teodor; Kępiński, Leszek

    2013-10-01

    Scanning thermal microscopy (SThM) is a very promising technique for local investigation of temperature and thermal properties of nanostructures with great application potential in contemporary nanoelectronics and nanotechnology. In order to increase the localization of SThM measurements, the size of probes has recently substantially decreased, which results in novel types of SThM probes manufactured with the use of modern silicon microfabrication technology. Quantitative SThM measurements with these probes need methods, which enable to assess the quality of thermal contact between the probe and the investigated surface. In this paper we propose a tip thermal mapping (TThM) procedure, which is used to estimate experimentally the distribution of power dissipated by the tip of an SThM probe. We also show that the proposed power dissipation model explains the results of active-mode SThM measurements and that the TThM procedure is reversible for a given probe and sample.

  2. Scanning electron microscopy of ascospores of Debaryomyces and Saccharomyces.

    PubMed

    Kurtzman, C P; Smiley, M J; Baker, F L

    1975-02-28

    Ascospores from species of Debaryomyces and the Torulaspora-group of Saccharomyces were examined by scanning electron microscopy. Ornamentation on ascospores of D. hansenii varied from short to long interconnected ridges or broad based, elongated conical protuberances. A spiral rigde system was detected on the ascospores of D. marama, but wart-like protuberances occurred on those of D. cantarelli, D. castellii, D. coudertii, D. formicarius, D. phaffii, D. vanriji and D. yarrowii. Ascospores of D. halotolerans did not have protuberances and the species appears to be identical with Pichia farinosa. Wart-like protuberances also were found on ascospores of S. delbrueckii, S. microellipsodes, S. rosei, S. inconspicuus, S. fermentati, S. montanus and S. vafer, but the ascospore surface of S. pretoriensis was covered by fine ridges. Short tapered ridges covered the ascospores of S. kloeckerianus.

  3. Probing Individual Ice Nucleation Events with Environmental Scanning Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Bingbing; China, Swarup; Knopf, Daniel; Gilles, Mary; Laskin, Alexander

    2016-04-01

    Heterogeneous ice nucleation is one of the processes of critical relevance to a range of topics in the fundamental and the applied science and technologies. Heterogeneous ice nucleation initiated by particles proceeds where microscopic properties of particle surfaces essentially control nucleation mechanisms. Ice nucleation in the atmosphere on particles governs the formation of ice and mixed phase clouds, which in turn influence the Earth's radiative budget and climate. Heterogeneous ice nucleation is still insufficiently understood and poses significant challenges in predictive understanding of climate change. We present a novel microscopy platform allowing observation of individual ice nucleation events at temperature range of 193-273 K and relative humidity relevant for ice formation in the atmospheric clouds. The approach utilizes a home built novel ice nucleation cell interfaced with Environmental Scanning Electron Microscope (IN-ESEM system). The IN-ESEM system is applied for direct observation of individual ice formation events, determining ice nucleation mechanisms, freezing temperatures, and relative humidity onsets. Reported microanalysis of the ice nucleating particles (INP) include elemental composition detected by the energy dispersed analysis of X-rays (EDX), and advanced speciation of the organic content in particles using scanning transmission x-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). The performance of the IN-ESEM system is validated through a set of experiments with kaolinite particles with known ice nucleation propensity. We demonstrate an application of the IN-ESEM system to identify and characterize individual INP within a complex mixture of ambient particles.

  4. Ocular mucin visualization by confocal laser scanning microscopy.

    PubMed

    Peral, Assumpta; Pintor, Jesús

    2008-05-01

    To describe a new method of visualizing human conjunctiva goblet cell mucin secretion by using a combination of impression cytology and laser scanning microscopy. By assembling a Z-stack of confocal microscopy images taken from human impression cytology samples, we obtained 3-dimensional information about the release and spread of goblet cell secretions above the conjunctival surface. After reconstruction and rendering of these images, analysis of the shape and spreading characteristics of the mucins permitted definition of the following parameters related to goblet cell secretion: mucin cloud height as the height of the top of the cloudlike mucin structure visible above the goblet cell opening and spread mucin thickness, which is the thickness of the mucin layer distributed over the surface of the conjunctiva. Several impression cytology samples of control and muco-deficient patients have been analyzed through the confocal laser scanning technique, and significant differences between these groups were found. Mucin cloud height and spread mucin thickness values for controls were 8.81 +/- 4.00 and 2.77 +/- 1.00 microm, respectively (n = 25). These values decreased by approximately 70% and 40%, respectively, for moderately mucodeficient subjects and by 84% and 48% for those with severe mucodeficiency. Classifying those individuals having mucin-related pathology may thus be possible on the basis of application of these techniques. In summary, we present a method of objectively identifying those individuals with problems associated with either a lack of mucins or a reduction in the distribution of these proteins over the ocular surface.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  6. Noise Analysis on Graphene Devices via Scanning Noise Microscopy

    NASA Astrophysics Data System (ADS)

    Cho, Duckhyung; Sung, Moon Gyu; Lee, Hyungwoo; Heo, Kwang; Byun, Kyung-Eun; Kim, Taekyeong; Seo, David H.; Seo, Sunae; Hong, Seunghun

    2013-03-01

    Until now, the studies about low-frequency noises in electronic devices have mostly relied on the scaling behaviour analysis of current noise measured from multiple devices with different resistance values. However, the fabrication of such multiple devices for noise analysis is a labor-intensive and time-consuming work. Herein, we developed the scanning noise microscopy (SNM) method for nanoscale noise analysis of electronic devices, which allowed us to measure the scaling behaviour of electrical current noises in a graphene-strip-based device. In this method, a conductive atomic force microscopy probe made a direct contact on the graphene strip channel in the device to measure the noise spectra through it. The SNM method enabled the investigation of the noise scaling behaviour using only a single device. In addition, the nanoscale noise map was obtained, which allowed us to study the effect of structural defects on the noise characteristics of the graphene strip channel. Our method should be a powerful strategy for nanoscale noise analysis and play a significant role in basic research on nanoscale devices.

  7. Scanning Surface Potential Microscopy of Spore Adhesion on Surfaces

    SciTech Connect

    Lee, Ida; Chung, Eunhyea; Kweon, Hyojin; Yiacoumi, Sotira; Tsouris, Costas

    2012-01-01

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

  8. Volume scanning electron microscopy for imaging biological ultrastructure.

    PubMed

    Titze, Benjamin; Genoud, Christel

    2016-11-01

    Electron microscopy (EM) has been a key imaging method to investigate biological ultrastructure for over six decades. In recent years, novel volume EM techniques have significantly advanced nanometre-scale imaging of cells and tissues in three dimensions. Previously, this had depended on the slow and error-prone manual tasks of cutting and handling large numbers of sections, and imaging them one-by-one with transmission EM. Now, automated volume imaging methods mostly based on scanning EM (SEM) allow faster and more reliable acquisition of serial images through tissue volumes and achieve higher z-resolution. Various software tools have been developed to manipulate the acquired image stacks and facilitate quantitative analysis. Here, we introduce three volume SEM methods: serial block-face electron microscopy (SBEM), focused ion beam SEM (FIB-SEM) and automated tape-collecting ultramicrotome SEM (ATUM-SEM). We discuss and compare their capabilities, provide an overview of the full volume SEM workflow for obtaining 3D datasets and showcase different applications for biological research.

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

    SciTech Connect

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

    2011-01-01

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

  10. Scanning Ion Conductance Microscopy for living cell membrane potential measurement

    NASA Astrophysics Data System (ADS)

    Panday, Namuna

    Recently, the existence of multiple micro-domains of extracellular potential around individual cells have been revealed by voltage reporter dye using fluorescence microscopy. One hypothesis is that these long lasting potential patterns play a vital role in regulating important cell activities such as embryonic patterning, regenerative repair and reduction of cancerous disorganization. We used multifunctional Scanning Ion Conductance Microscopy (SICM) to study these extracellular potential patterns of single cell with higher spatial resolution. To validate this novel technique, we compared the extracellular potential distribution on the fixed HeLa cell surface and Polydimethylsiloxane (PDMS) surface and found significant difference. We then measured the extracellular potential distributions of living melanocytes and melanoma cells and found both the mean magnitude and spatial variation of extracellular potential of the melanoma cells are bigger than those of melanocytes. As compared to the voltage reporter dye based fluorescence microscope method, SICM can achieve quantitative potential measurements of non-labeled living cell membranes with higher spatial resolution.

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

    PubMed Central

    Goldsbury, Claire; Baxa, Ulrich; Simon, Martha N.; Steven, Alasdair C.; Engel, Andreas; Wall, Joseph S.; Aebi, Ueli; Müller, Shirley A.

    2010-01-01

    Amyloid fibrils are filamentous protein aggregates implicated in several common diseases like Alzheimer’s disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies like Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR). PMID:20868754

  12. Amyloid structure and assembly: insights from scanning transmission electron microscopy.

    PubMed

    Goldsbury, Claire; Baxa, Ulrich; Simon, Martha N; Steven, Alasdair C; Engel, Andreas; Wall, Joseph S; Aebi, Ueli; Müller, Shirley A

    2011-01-01

    Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR). Copyright © 2010 Elsevier Inc. All rights reserved.

  13. Morphological classification of bioaerosols from composting using scanning electron microscopy

    SciTech Connect

    Tamer Vestlund, A.; Al-Ashaab, R.; Tyrrel, S.F.; Longhurst, P.J.; Pollard, S.J.T.; Drew, G.H.

    2014-07-15

    Highlights: • Bioaerosols were captured using the filter method. • Bioaerosols were analysed using scanning electron microscope. • Bioaerosols were classified on the basis of morphology. • Single small cells were found more frequently than aggregates and larger cells. • Smaller cells may disperse further than heavier aggregate structures. - Abstract: This research classifies the physical morphology (form and structure) of bioaerosols emitted from open windrow composting. Aggregation state, shape and size of the particles captured are reported alongside the implications for bioaerosol dispersal after release. Bioaerosol sampling took place at a composting facility using personal air filter samplers. Samples were analysed using scanning electron microscopy. Particles were released mainly as small (<1 μm) single, spherical cells, followed by larger (>1 μm) single cells, with aggregates occurring in smaller proportions. Most aggregates consisted of clusters of 2–3 particles as opposed to chains, and were <10 μm in size. No cells were attached to soil debris or wood particles. These small single cells or small aggregates are more likely to disperse further downwind from source, and cell viability may be reduced due to increased exposure to environmental factors.

  14. Scanning Tunneling Microscopy of SILICON(100) 2 X 1

    NASA Astrophysics Data System (ADS)

    Hubacek, Jerome S.

    1992-01-01

    The Si(100) 2 x 1 surface, a technologically important surface in microelectronics and silicon molecular beam epitaxy (MBE), has been studied with the scanning tunneling microscope (STM) to attempt to clear up the controversy that surrounds previous studies of this surface. To this end, an ultra-high vacuum (UHV) STM/surface science system has been designed and constructed to study semiconductor surfaces. Clean Si(100) 2 x 1 surfaces have been prepared and imaged with the STM. Atomic resolution images probing both the filled states and empty states indicate that the surface consists of statically buckled dimer rows. With electronic device dimensions shrinking to smaller and smaller sizes, the Si-SiO_2 interface is becoming increasingly important and, although it is the most popular interface used in the microelectronics industry, little is known about the initial stages of oxidation of the Si(100) surface. Scanning tunneling microscopy has been employed to examine Si(100) 2 x 1 surfaces exposed to molecular oxygen in UHV. Ordered rows of bright and dark spots, rotated 45^circ from the silicon dimer rows, appear in the STM images, suggesting that the Si(100)-SiO_2 interface may be explained with a beta -cristobalite(100) structure rotated by 45^ circ on the Si(100) surface.

  15. Spatial resolution and information transfer in scanning transmission electron microscopy.

    PubMed

    Peng, Yiping; Oxley, Mark P; Lupini, Andrew R; Chisholm, Matthew F; Pennycook, Stephen J

    2008-02-01

    The relation between image resolution and information transfer is explored. It is shown that the existence of higher frequency transfer in the image is just a necessary but not sufficient condition for the achievement of higher resolution. Adopting a two-point resolution criterion, we suggest that a 10% contrast level between two features in an image should be used as a practical definition of resolution. In the context of scanning transmission electron microscopy, it is shown that the channeling effect does not have a direct connection with image resolution because sharp channeling peaks do not move with the scanning probe. Through a quantitative comparison between experimental image and simulation, a Fourier-space approach is proposed to estimate defocus and sample thickness. The effective atom size in Z-contrast imaging depends on the annular detector's inner angle. Therefore, an optimum angle exists for the highest resolution as a trade-off between reduced atom size and reduced signal with limited information transfer due to noise.

  16. All-optical photoacoustic microscopy using a MEMS scanning mirror

    NASA Astrophysics Data System (ADS)

    Chen, Sung-Liang; Xie, Zhixing; Ling, Tao; Wei, Xunbin; Guo, L. Jay; Wang, Xueding

    2013-03-01

    It has been studied that a potential marker to obtain prognostic information about bladder cancer is tumor neoangiogenesis, which can be quantified by morphometric characteristics such as microvascular density. Photoacoustic microscopy (PAM) can render sensitive three-dimensional (3D) mapping of microvasculature, providing promise to evaluate the neoangiogenesis that is closely related to the diagnosis of bladder cancer. To ensure good image quality, it is desired to acquire bladder PAM images from its inside via the urethra, like conventional cystoscope. Previously, we demonstrated all-optical PAM systems using polymer microring resonators to detect photoacoustic signals and galvanometer mirrors for laser scanning. In this work, we build a miniature PAM system using a microelectromechanical systems (MEMS) scanning mirror, demonstrating a prototype of an endoscopic PAM head capable of high imaging quality of the bladder. The system has high resolutions of 17.5 μm in lateral direction and 19 μm in the axial direction at a distance of 5.4 mm. Images of printed grids and the 3D structure of microvasculature in animal bladders ex vivo by the system are demonstrated.

  17. Investigating ultraflexible freestanding graphene by scanning tunneling microscopy and spectroscopy

    NASA Astrophysics Data System (ADS)

    Breitwieser, R.; Hu, Yu-Cheng; Chao, Yen Cheng; Tzeng, Yi Ren; Liou, Sz-Chian; Lin, Keng Ching; Chen, Chih Wei; Pai, Woei Wu

    2017-08-01

    A strictly two-dimensional (2D) material such as freestanding graphene (FSG) is rarely investigated at the atomic scale by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). A basic difficulty in probing FSG by STM and STS is the mechanical instability when a highly compliant 2D atomic layer interacts with a proximal tip. Here we report a detailed method to conduct reliable STM and STS on FSG with atomic precision. We found that FSG is intrinsically rippled and exhibits a nonlinear strain-stress relation under applied normal forces; it shows a very soft region of bending strain and stiffer regions of in-plane tensile strain once the nanoscale ripples of FSG are eliminated. The elimination of the nanoripples can be controlled by tip-induced pulling or pushing force through the so-called closed-loop Z-V STS mode which can monitor the FSG deformation. A key factor for controllable STM and STS measurements is to select tunneling set points to place FSG in metastable configurations, as determined from stress-strain (i.e., Z-V) response. Atomic imaging and electronic states thus measured must be interpreted by considering the dynamical deformation of FSG as tunneling parameters, and therefore tip-FSG forces, are varied.

  18. Study of Biomedical Specimens Using Scanning Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Doroski, D.; Tittmann, B. R.; Miyasaka, C.

    Microscopy is a paramount part of science and the medical field. The optical microscope (OM), scanning electron microscope (SEM), and atomic force microscope (AFM) are commonly used for the imaging of biomedical cells and tissues. Unfortunately, these conventional microscopes have major disadvantages. The atomic force microscope is still underdeveloped in imaging of living biomedical specimens. The OM and SEM require dead specimens for imaging, and cannot image the subsurface of thick specimens. Development of the scanning acoustic microscope (SAM) is a solution to these problems. The SAM has the ability to image living specimens for extended periods of time without harming them, can image the subsurface of the sample, can image thick specimens, and can obtain information about mechanical properties of the specimen. In this study images of esophagus tissue were obtained using an OM, SEM, and SAM. While OM and SEM have been established as valuable tools for imaging of biological tissue samples not much basic imaging of histological structures of biological specimens has been done using the SAM. The goal was to create an imaging baseline for the SAM that showed that it could function at the level of the OM and the SEM. When imaging the tissues, all three of the microscopes yielded similar images

  19. Catalytic reaction processes revealed by scanning probe microscopy. [corrected].

    PubMed

    Jiang, Peng; Bao, Xinhe; Salmeron, Miquel

    2015-05-19

    Heterogeneous catalysis is of great importance for modern society. About 80% of the chemicals are produced by catalytic reactions. Green energy production and utilization as well as environmental protection also need efficient catalysts. Understanding the reaction mechanisms is crucial to improve the existing catalysts and develop new ones with better activity, selectivity, and stability. Three components are involved in one catalytic reaction: reactant, product, and catalyst. The catalytic reaction process consists of a series of elementary steps: adsorption, diffusion, reaction, and desorption. During reaction, the catalyst surface can change at the atomic level, with roughening, sintering, and segregation processes occurring dynamically in response to the reaction conditions. Therefore, it is imperative to obtain atomic-scale information for understanding catalytic reactions. Scanning probe microscopy (SPM) is a very appropriate tool for catalytic research at the atomic scale because of its unique atomic-resolution capability. A distinguishing feature of SPM, compared to other surface characterization techniques, such as X-ray photoelectron spectroscopy, is that there is no intrinsic limitation for SPM to work under realistic reaction conditions (usually high temperature and high pressure). Therefore, since it was introduced in 1981, scanning tunneling microscopy (STM) has been widely used to investigate the adsorption, diffusion, reaction, and desorption processes on solid catalyst surfaces at the atomic level. STM can also monitor dynamic changes of catalyst surfaces during reactions. These invaluable microscopic insights have not only deepened the understanding of catalytic processes, but also provided important guidance for the development of new catalysts. This Account will focus on elementary reaction processes revealed by SPM. First, we will demonstrate the power of SPM to investigate the adsorption and diffusion process of reactants on catalyst surfaces

  20. Scanning hall probe microscopy (SHPM) using quartz crystal AFM feedback.

    PubMed

    Dede, M; Urkmen, K; Girişen, O; Atabak, M; Oral, A; Farrer, I; Ritchie, D

    2008-02-01

    Scanning Hall Probe Microscopy (SHPM) is a quantitative and non-invasive technique for imaging localized surface magnetic field fluctuations such as ferromagnetic domains with high spatial and magnetic field resolution of approximately 50 nm and 7 mG/Hz(1/2) at room temperature. In the SHPM technique, scanning tunneling microscope (STM) or atomic force microscope (AFM) feedback is used to keep the Hall sensor in close proximity of the sample surface. However, STM tracking SHPM requires conductive samples; therefore the insulating substrates have to be coated with a thin layer of gold. This constraint can be eliminated with the AFM feedback using sophisticated Hall probes that are integrated with AFM cantilevers. However it is very difficult to micro fabricate these sensors. In this work, we have eliminated the difficulty in the cantilever-Hall probe integration process, just by gluing a Hall Probe chip to a quartz crystal tuning fork force sensor. The Hall sensor chip is simply glued at the end of a 32.768 kHz or 100 kHz Quartz crystal, which is used as force sensor. An LT-SHPM system is used to scan the samples. The sensor assembly is dithered at the resonance frequency using a digital Phase Locked Loop circuit and frequency shifts are used for AFM tracking. SHPM electronics is modified to detect AFM topography and the frequency shift, along with the magnetic field image. Magnetic domains and topography of an Iron Garnet thin film crystal, NdFeB demagnetised magnet and hard disk samples are presented at room temperature. The performance is found to be comparable with the SHPM using STM feedback.

  1. Post-processing strategies in image scanning microscopy.

    PubMed

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

    2015-10-15

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

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

    PubMed

    Konopka, K

    2006-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Seacor, Taylor; Howell, Carina

    2013-03-01

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

  4. Comparison of scanning ion conductance microscopy with atomic force microscopy for cell imaging.

    PubMed

    Rheinlaender, Johannes; Geisse, Nicholas A; Proksch, Roger; Schäffer, Tilman E

    2011-01-18

    We present the first direct comparison of scanning ion conductance microscopy (SICM) with atomic force microscopy (AFM) for cell imaging. By imaging the same fibroblast or myoblast cell with both technologies in series, we highlight their advantages and disadvantages with respect to cell imaging. The finite imaging force applied to the sample in AFM imaging results in a coupling of mechanical sample properties into the measured sample topography. For soft samples such as cells this leads to artifacts in the measured topography and to elastic deformation, which we demonstrate by imaging whole fixed cells and cell extensions at high resolution. SICM imaging, on the other hand, has a noncontact character and can provide the true topography of soft samples at a comparable resolution.

  5. Atomic force microscopy and scanning electron microscopy study of MgO(110) surface faceting

    NASA Astrophysics Data System (ADS)

    Giese, D. R.; Lamelas, F. J.; Owen, H. A.; Plass, R.; Gajdardziska-Josifovska, M.

    2000-06-01

    Phosphoric- and nitric-acid etching of the MgO(110) surface generates vicinal faceting in both the <001> and <110> directions. Vacuum annealing (to 1000°C) does not introduce thermal faceting, and does not alter the chemical-etch morphology. Three types of acid-induced faceting (early-stage pits, later-stage grooves, and inverted trapezoidal pyramids) are seen as a function of etching time. Facet-angle analysis by atomic force microscopy (AFM) and scanning electron microscopy (SEM) shows the etch morphology to be vicinal, with angles in the range of 9° to 23°, not the low-energy {100} planes expected from minimization of surface energy.

  6. Aberration-corrected scanning transmission electron microscopy for complex transition metal oxides

    NASA Astrophysics Data System (ADS)

    Qing-Hua, Zhang; Dong-Dong, Xiao; Lin, Gu

    2016-06-01

    Lattice, charge, orbital, and spin are the four fundamental degrees of freedom in condensed matter, of which the interactive coupling derives tremendous novel physical phenomena, such as high-temperature superconductivity (high-T c SC) and colossal magnetoresistance (CMR) in strongly correlated electronic system. Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it, and also indispensable for designing new materials and devices. Scanning transmission electron microscopy (STEM) integrating multiple techniques of structure imaging and spectrum analysis, is a comprehensive platform for providing structural, chemical and electronic information of materials with a high spatial resolution. Benefiting from the development of aberration correctors, STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization; many improvements have been achieved in recent years, thereby giving an in-depth insight into material research. Here, we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides; atomic-scale mapping of ferroelectric polarization, octahedral distortions and rotations, valence state, coordination and spin ordering are presented. We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides. Project supported by the National Key Basic Research Project, China (Grant No. 2014CB921002), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07030200), and the National Natural Science Foundation of China (Grant Nos. 51522212 and 51421002).

  7. Image enhancement with two-photon laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Chun-Ming

    1998-07-01

    Although confocal microscopy provides an efficient means of fluorescence imaging, many obstacles including extensive photobleaching and limited penetration depths limit its application. Emergence of two-photon laser scanning microscopy (TPLSM), with limited excitation volume, successfully overcomes those difficulties. Not only is TPLSM shown to have much less photobleaching and better penetration depths than CLSM, but also it is capable of doing UV imaging without using special UV optical elements. Several different aspects of TPLSM are discussed in the dissertation. The progress of 3-D fluorescence microscopy, a historical retrospective of two-photon excitation, the physics of two-photon excitation and our instrument setup are discussed in the first chapter. In chapter II, a qualitative and quantitative confirmation of two-photon excitation, optical transfer efficiency, point spread function and resolution, signal-to-noise ratio, and two-photon excitation spectrum are presented. Chapter III shows the comparison between TPLSM and CLSM. Although CLSM has slightly better resolution than TPLSM, TPLSM has much less photobleaching and toxicity, greater penetration depth, less signal cross talk, and better signal collecting efficiency. Image deconvolution techniques with CLSM and TPLSM are discussed in chapter IV. Using this image processing methods and acquired PSF, we improved the resolution of CLSM and TPLSM dramatically. These deblurring techniques were applied to study the positions of proteins in the pre- and postsynaptic compartments of rat hippocampal culture cells. The improved resolution enabled us to distinguish the positions of Synapsin I, CaM Kinase II, and PSD-95, which could only be done with electron microscopy before. In chapter V, image degradation due to brain tissue scattering is discussed. Emission signals with long wavelengths were shown to have better resolution and image contrast because of less tissue scattering. This result shows the necessity

  8. Scanning probe microscopy investigation of complex-oxide heterostructures

    NASA Astrophysics Data System (ADS)

    Bi, Feng

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

  9. Scanning moiré fringe imaging by scanning transmission electron microscopy.

    PubMed

    Su, Dong; Zhu, Yimei

    2010-02-01

    A type of artificial contrast found in annular dark-field imaging is generated by spatial interference between the scanning grating of the electron beam and the specimen atomic lattice. The contrast is analogous to moiré fringes observed in conventional transmission electron microscopy. We propose using this scanning interference for retrieving information about the atomic lattice structure at medium magnifications. Compared with the STEM atomic imaging at high magnifications, this approach might have several advantages including easy observation of lattice discontinuities and reduction of image degradation from carbon contamination and beam damage. Application of the technique to reveal the Burgers vector of misfit dislocations at the interface of epitaxial films is demonstrated and its potential for studying strain fields is discussed.

  10. 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

  11. C58 on Au(111): A scanning tunneling microscopy study

    NASA Astrophysics Data System (ADS)

    Bajales, Noelia; Schmaus, Stefan; Miyamashi, Toshio; Wulfhekel, Wulf; Wilhelm, Jan; Walz, Michael; Stendel, Melanie; Bagrets, Alexej; Evers, Ferdinand; Ulas, Seyithan; Kern, Bastian; Böttcher, Artur; Kappes, Manfred M.

    2013-03-01

    C58 fullerenes were adsorbed onto room temperature Au(111) surface by low-energy (˜6 eV) cluster ion beam deposition under ultrahigh vacuum conditions. The topographic and electronic properties of the deposits were monitored by means of scanning tunnelling microscopy (STM at 4.2 K). Topographic images reveal that at low coverages fullerene cages are pinned by point dislocation defects on the herringbone reconstructed gold terraces (as well as by step edges). At intermediate coverages, pinned monomers act as nucleation centres for the formation of oligomeric C58 chains and 2D islands. At the largest coverages studied, the surface becomes covered by 3D interlinked C58 cages. STM topographic images of pinned single adsorbates are essentially featureless. The corresponding local densities of states are consistent with strong cage-substrate interactions. Topographic images of [C58]n oligomers show a stripe-like intensity pattern oriented perpendicular to the axis connecting the cage centers. This striped pattern becomes even more pronounced in maps of the local density of states. As supported by density functional theory, DFT calculations, and also by analogous STM images previously obtained for C60 polymers [M. Nakaya, Y. Kuwahara, M. Aono, and T. Nakayama, J. Nanosci. Nanotechnol. 11, 2829 (2011)], 10.1166/jnn.2011.3898, we conclude that these striped orbital patterns are a fingerprint of covalent intercage bonds. For thick C58 films we have derived a bandgap of 1.2 eV from scanning tunnelling spectroscopy data confirming that the outermost C58 layer behaves as a wide band semiconductor.

  12. Scanning tunneling microscopy of graphene on Ru(0001)

    NASA Astrophysics Data System (ADS)

    Marchini, S.; Günther, S.; Wintterlin, J.

    2007-08-01

    After prolonged annealing of a Ru(0001) sample in ultrahigh vacuum a superstructure with a periodicity of ˜30Å was observed by scanning tunneling microscopy (STM). Using x-ray photoelectron spectroscopy it was found that the surface is covered by graphitic carbon. Auger electron spectroscopy shows that between 1000 and 1400K carbon segregates to the surface. STM images recorded after annealing to increasing temperatures display islands of the superstructure, until, after annealing to T⩾1400K , it covers the entire surface. The morphology of the superstructure shows that it consists of a single graphene layer. Atomically resolved STM images and low-energy electron diffraction reveal an (11×11) structure or incommensurate structure close to this periodicity superimposed by 12×12 graphene cells. The lattice mismatch causes a moiré pattern. Unlike the common orientational disorder of adsorbed graphene, the graphene layer on Ru(0001) shows a single phase and very good rotational alignment. Misorientations near defects in the overlayer only amount to ˜1° , and the periodicity of ˜30Å is unaffected. In contrast to bulk graphite both carbon atoms in the graphene unit cell were resolved by STM, with varying contrast depending on the position above the Ru atoms. The filled and empty state images of the moiré structure differ massively, and electronic states at -0.4 and +0.2V were detected by scanning tunneling spectroscopy. The data indicate a significantly stronger chemical interaction between graphene and the metal surface than between neighboring layers in bulk graphite. The uniformity of the structure and its stability at high temperatures and in air suggest an application as template for nanostructures.

  13. Accurate virus quantitation using a Scanning Transmission Electron Microscopy (STEM) detector in a scanning electron microscope.

    PubMed

    Blancett, Candace D; Fetterer, David P; Koistinen, Keith A; Morazzani, Elaine M; Monninger, Mitchell K; Piper, Ashley E; Kuehl, Kathleen A; Kearney, Brian J; Norris, Sarah L; Rossi, Cynthia A; Glass, Pamela J; Sun, Mei G

    2017-10-01

    A method for accurate quantitation of virus particles has long been sought, but a perfect method still eludes the scientific community. Electron Microscopy (EM) quantitation is a valuable technique because it provides direct morphology information and counts of all viral particles, whether or not they are infectious. In the past, EM negative stain quantitation methods have been cited as inaccurate, non-reproducible, and with detection limits that were too high to be useful. To improve accuracy and reproducibility, we have developed a method termed Scanning Transmission Electron Microscopy - Virus Quantitation (STEM-VQ), which simplifies sample preparation and uses a high throughput STEM detector in a Scanning Electron Microscope (SEM) coupled with commercially available software. In this paper, we demonstrate STEM-VQ with an alphavirus stock preparation to present the method's accuracy and reproducibility, including a comparison of STEM-VQ to viral plaque assay and the ViroCyt Virus Counter. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  14. 3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy

    PubMed Central

    Lerner, Thomas R.; Burden, Jemima J.; Nkwe, David O.; Pelchen-Matthews, Annegret; Domart, Marie-Charlotte; Durgan, Joanne; Weston, Anne; Jones, Martin L.; Peddie, Christopher J.; Carzaniga, Raffaella; Florey, Oliver; Marsh, Mark; Gutierrez, Maximiliano G.

    2017-01-01

    ABSTRACT The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here, we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy, and 3D image processing and analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research. PMID:27445312

  15. 3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy.

    PubMed

    Russell, Matthew R G; Lerner, Thomas R; Burden, Jemima J; Nkwe, David O; Pelchen-Matthews, Annegret; Domart, Marie-Charlotte; Durgan, Joanne; Weston, Anne; Jones, Martin L; Peddie, Christopher J; Carzaniga, Raffaella; Florey, Oliver; Marsh, Mark; Gutierrez, Maximiliano G; Collinson, Lucy M

    2017-01-01

    The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here, we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy, and 3D image processing and analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research. © 2017. Published by The Company of Biologists Ltd.

  16. Digital image enhancement for in vivo laser scanning microscopy.

    PubMed

    Gruber, Martin J; Wackernagel, Alexandra; Richtig, Erika; Koller, Silvia; Kerl, Helmut; Smolle, Josef

    2005-11-01

    In vivo confocal laser scanning microscopy (CLSM) is a new method that provides skin images in horizontal plane at a level of resolution that allows to view microanatomic structures. This study examines whether certain digital image-processing steps can increase the visibility of various structures in CLSM. Fifty images were taken from normal skin of 25 probands, and 39 image enhancement procedures were created. Eight procedures that seemed to provide some quality enhancement were deliberately selected for further evaluation. Subsequently, a collection of random pairs of the original image and an image submitted to any of the eight selected procedures was rated by five independent observers. In three of the eight procedures tested, the modified image was significantly preferred to the original image (chi2-test,: P< or =0.001). In particular, smoothing, shading correction, delineate and grey-level normalization in various combinations were helpful in showing the characteristic honeycomb pattern, pigmented basal cell layer, cell borders and the nuclei more clearly. Digital image processing may help to increase visibility of in vivo CLSM images.

  17. Band excitation method applicable to scanning probe microscopy

    DOEpatents

    Jesse, Stephen [Knoxville, TN; Kalinin, Sergei V [Knoxville, TN

    2010-08-17

    Methods and apparatus are described for scanning probe microscopy. A method includes generating a band excitation (BE) signal having finite and predefined amplitude and phase spectrum in at least a first predefined frequency band; exciting a probe using the band excitation signal; obtaining data by measuring a response of the probe in at least a second predefined frequency band; and extracting at least one relevant dynamic parameter of the response of the probe in a predefined range including analyzing the obtained data. The BE signal can be synthesized prior to imaging (static band excitation), or adjusted at each pixel or spectroscopy step to accommodate changes in sample properties (adaptive band excitation). An apparatus includes a band excitation signal generator; a probe coupled to the band excitation signal generator; a detector coupled to the probe; and a relevant dynamic parameter extractor component coupled to the detector, the relevant dynamic parameter extractor including a processor that performs a mathematical transform selected from the group consisting of an integral transform and a discrete transform.

  18. Band excitation method applicable to scanning probe microscopy

    DOEpatents

    Jesse, Stephen; Kalinin, Sergei V

    2013-05-28

    Methods and apparatus are described for scanning probe microscopy. A method includes generating a band excitation (BE) signal having finite and predefined amplitude and phase spectrum in at least a first predefined frequency band; exciting a probe using the band excitation signal; obtaining data by measuring a response of the probe in at least a second predefined frequency band; and extracting at least one relevant dynamic parameter of the response of the probe in a predefined range including analyzing the obtained data. The BE signal can be synthesized prior to imaging (static band excitation), or adjusted at each pixel or spectroscopy step to accommodate changes in sample properties (adaptive band excitation). An apparatus includes a band excitation signal generator; a probe coupled to the band excitation signal generator; a detector coupled to the probe; and a relevant dynamic parameter extractor component coupled to the detector, the relevant dynamic parameter extractor including a processor that performs a mathematical transform selected from the group consisting of an integral transform and a discrete transform.

  19. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    NASA Astrophysics Data System (ADS)

    Lunov, O.; Churpita, O.; Zablotskii, V.; Deyneka, I. G.; Meshkovskii, I. K.; Jäger, A.; Syková, E.; Kubinová, Š.; Dejneka, A.

    2015-02-01

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin-stained rat skin sections from plasma-treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy.

  20. Intracellular phthalocyanine localization: confocal laser scanning microscopy studies

    NASA Astrophysics Data System (ADS)

    Chernyaeva, Elena B.; Greve, Jan; de Grooth, Bart G.; Van Leeuwen, A. G.

    1994-02-01

    Phthalocyanines (Pc) are promising second-generation photosensitizers for the photodynamic therapy (PDT) of cancer. We report on the tetrasulfonated aluminum phthalocyanine (AlPcS4) localization in cultured Chinese hamster lung cells studied by means of confocal laser scanning microscopy (CLSM). In these cells AlPcS4 was found in granules surrounding Golgi apparatus and in the peripheral cytoplasmic region. Peripheral Pc-containing granules partially coincided with the acidic cellular compartments. The effect of irradiation with light on Pc intracellular distribution was also studied. In the Pc-free medium disruption of some Pc- containing granules was observed followed by appearance of Pc fluorescence in the cell plasma membrane, the nuclear envelope, and the near-nuclear region. When cells were irradiated in the presence of Pc in external medium a drastic increase of membrane permeability to Pc was observed, followed by Pc binding the cell plasma membrane, nuclear envelope, and some structures in the cytoplasm. Diffusive Pc fluorescence in the nucleus was also observed. The implication of observed Pc redistribution caused by irradiation with light for the PDT protocol is discussed.

  1. Managing multiple image stacks from confocal laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Zerbe, Joerg; Goetze, Christian H.; Zuschratter, Werner

    1999-05-01

    A major goal in neuroanatomy is to obtain precise information about the functional organization of neuronal assemblies and their interconnections. Therefore, the analysis of histological sections frequently requires high resolution images in combination with an overview about the structure. To overcome this conflict we have previously introduced a software for the automatic acquisition of multiple image stacks (3D-MISA) in confocal laser scanning microscopy. Here, we describe a Windows NT based software for fast and easy navigation through the multiple images stacks (MIS-browser), the visualization of individual channels and layers and the selection of user defined subregions. In addition, the MIS browser provides useful tools for the visualization and evaluation of the datavolume, as for instance brightness and contrast corrections of individual layers and channels. Moreover, it includes a maximum intensity projection, panning and zoom in/out functions within selected channels or focal planes (x/y) and tracking along the z-axis. The import module accepts any tiff-format and reconstructs the original image arrangement after the user has defined the sequence of images in x/y and z and the number of channels. The implemented export module allows storage of user defined subregions (new single image stacks) for further 3D-reconstruction and evaluation.

  2. Scanning SQUID microscopy of local superconductivity in inhomogeneous combinatorial ceramics.

    PubMed

    Iranmanesh, Mitra; Stir, Manuela; Kirtley, John R; Hulliger, Jürg

    2014-11-24

    Although combinatorial solid-state chemistry promises to be an efficient way to search for new superconducting compounds, the problem of determining which compositions are strongly diamagnetic in a mixed-phase sample is challenging. By means of reactions in a system of randomly mixed starting components (Ca, Sr, Ba, La, Y, Pb, Bi, Tl, and Cu oxides), samples were produced that showed an onset of diamagnetic response above 115 K in bulk measurements. Imaging of this diamagnetic response in ceramic samples by scanning SQUID microscopy (SSM) revealed local superconducting areas with sizes down to as small as the spatial resolution of a few micrometers. In addition, locally formed superconducting matter was extracted from mixed-phase samples by magnetic separation. The analysis of single grains (d<80 μm) by X-ray diffraction, elemental analysis, and bulk SQUID measurements allowed Tl2Ca3Ba2Cu4O12, TlCaBaSrCu2O(7-δ), BaPb(0.5)Bi(0.25)Tl(0.25)O(3-δ), TlBa2Ca2Cu3O9, Tl2Ba2CaCu2O8, and YBa2Cu3O7 phases to be identified. SSM, in combination with other diagnostic techniques, is therefore shown to be a useful instrument to analyze inhomogeneous reaction products in the solid-state chemistry of materials showing magnetic properties.

  3. Three-Dimensional Scanning Transmission Electron Microscopy of Biological Specimens

    PubMed Central

    de Jonge, Niels; Sougrat, Rachid; Northan, Brian M.; Pennycook, Stephen J.

    2010-01-01

    A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM). The specimen was a metallic replica of the biological structure comprising Pt nanoparticles 2–3 nm in diameter, with a high stability under electron beam radiation. The 3D dataset was processed by an automated deconvolution procedure. The lateral resolution was 1.1 nm, set by pixel size. Particles differing by only 10 nm in vertical position were identified as separate objects with greater than 20% dip in contrast between them. We refer to this value as the axial resolution of the deconvolution or reconstruction, the ability to recognize two objects, which were unresolved in the original dataset. The resolution of the reconstruction is comparable to that achieved by tilt-series transmission electron microscopy. However, the focal-series method does not require mechanical tilting and is therefore much faster. 3D STEM images were also recorded of the Golgi ribbon in conventional thin sections containing 3T3 cells with a comparable axial resolution in the deconvolved dataset. PMID:20082729

  4. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    SciTech Connect

    Lunov, O. Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A.; Deyneka, I. G.; Meshkovskii, I. K.; Syková, E.; Kubinová, Š.

    2015-02-02

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy.

  5. Applications of confocal laser scanning microscopy to dental bonding.

    PubMed

    Pioch, T; Stotz, S; Staehle, H J; Duschner, H

    1997-11-01

    The introduction of confocal laser scanning microscopy (CLSM) has provided a valuable new technique for the visualization of bonding structures such as a hybrid layer in dentin (Watson, 1989, 1991). In the case of seven commercially-available dentin bonding systems, it could be demonstrated that the CLSM renders considerably more detailed information than the SEM because of its non-destructive nature and because of the possibility of a distinction between components of bonding agents. With most of the bonding systems, measurements of the thickness of the hybrid layer could be carried out when the primer component was labeled with rhodamine B. It was found that this thickness is significantly increased by increases in etching time and only slightly decreased by increases in the drying time of the dentin and of the primer. When rhodamine B was used for dye penetration tests on four different dentin bonding systems, a leakage within the demineralized zone in the dentin was found in each of the specimens. This structure appears similar to that which Sano et al. (1995) called "nanoleakage". The amount of nanoleakage could not be measured by this method. In the case of enamel or ceramic bonding, a penetration zone was found which corresponded to the etching patterns found in enamel and ceramics, respectively. We conclude that CLSM can offer a wealth of new information about bonding morphology and, therefore, should be used in addition to conventional methods so that the maximum information can be obtained.

  6. Scanning electron microscopy applied to seed-borne fungi examination.

    PubMed

    Alves, Marcelo de Carvalho; Pozza, Edson Ampélio

    2009-07-01

    The aim of this study was to test the standard scanning electron microscopy (SEM) as a potential alternative to study seed-borne fungi in seeds, by two different conditions of blotter test and water restriction treatment. In the blotter test, seeds were subjected to conditions that enabled pathogen growth and expression, whereas the water restriction method consisted in preventing seed germination during the incubation period, resulting in the artificial inoculation of fungi. In the first condition, seeds of common bean (Phaseolus vulgaris L.), maize (Zea mays L.), and cotton (Gossypium hirsutum L.) were submitted to the standard blotter test and then prepared and observed with SEM. In the second condition, seeds of cotton (G. hirsutum), soybean (Glycine max L.), and common bean (P. vulgaris L.) were, respectively, inoculated with Colletotrichum gossypii var. cephalosporioides, Colletotrichum truncatum, and Colletotrichum lindemuthianum by the water restriction technique, followed by preparation and observation with SEM. The standard SEM methodology was adopted to prepare the specimens. Considering the seeds submitted to the blotter test, it was possible to identify Fusarium sp. on maize, C. gossypii var. cephalosporioides, and Fusarium oxysporum on cotton, Aspergillus flavus, Penicillium sp., Rhizopus sp., and Mucor sp. on common bean. Structures of C. gossypii var. cephalosporioides, C. truncatum, and C. lindemuthianum were observed in the surface of inoculated seeds. (c) 2009 Wiley-Liss, Inc.

  7. Materials characterisation by angle-resolved scanning transmission electron microscopy

    PubMed Central

    Müller-Caspary, Knut; Oppermann, Oliver; Grieb, Tim; Krause, Florian F.; Rosenauer, Andreas; Schowalter, Marco; Mehrtens, Thorsten; Beyer, Andreas; Volz, Kerstin; Potapov, Pavel

    2016-01-01

    Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaNxAs1−x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with GexSi1−x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16–255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering. PMID:27849001

  8. Three-dimensional scanning transmission electron microscopy of biological specimens

    SciTech Connect

    De Jonge, Niels; Sougrat, Rachid; Northan, Brian; Pennycook, Stephen J

    2010-01-01

    A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM). The specimen was a metallic replica of the biological structure comprising Pt nanoparticles 2 - 3 nm in diameter, with a high stability under electron beam radiation. The 3D dataset was processed by an automated deconvolution procedure. The lateral resolution was 1.1 nm, set by pixel size. Particles differing by only 10 nm in vertical position were identified as separate objects with greater than 20% dip in contrast between them. We refer to this value as the axial resolution of the deconvolution or reconstruction, the ability to recognize two objects, which were unresolved in the original data set. The precision of the height determination was 0.2 nm. The resolution of the reconstruction is comparable to that achieved by tilt-series transmission electron microscopy (TEM). However, the focal-series method does not require mechanical tilting and is therefore much faster. 3D STEM images were also recorded of the Golgi ribbon in conventional thin sections containing 3T3 cells with a comparable axial resolution in the deconvolved data set.

  9. Humidity effects on scanning polarization force microscopy imaging

    NASA Astrophysics Data System (ADS)

    Shen, Yue; Zhou, Yuan; Sun, Yanxia; Zhang, Lijuan; Wang, Ying; Hu, Jun; Zhang, Yi

    2017-08-01

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

  10. Active nanocharacterization of nanofunctional materials by scanning tunneling microscopy.

    PubMed

    Fujita, Daisuke; Sagisaka, Keisuke

    2008-01-01

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

  11. Active nanocharacterization of nanofunctional materials by scanning tunneling microscopy

    PubMed Central

    Fujita, Daisuke; Sagisaka, Keisuke

    2008-01-01

    Recent developments in the application of scanning tunneling microscopy (STM) to nanofabrication and nanocharacterization are reviewed. The main focus of this paper is to outline techniques for depositing and manipulating nanometer-scale structures using STM tips. Firstly, the transfer of STM tip material through the application of voltage pulses is introduced. The highly reproducible fabrication of metallic silver nanodots and nanowires is discussed. The mechanism is thought to be spontaneous point-contact formation caused by field-enhanced diffusion to the apex of the tip. Transfer through the application of z-direction pulses is also introduced. Sub-nanometer displacement pulses along the z-direction form point contacts that can be used for reproducible nanodot deposition. Next, the discovery of the STM structural manipulation of surface phases is discussed. It has been demonstrated that superstructures on Si(001) surfaces can be reverse-manipulated by controlling the injected carriers. Finally, the fabrication of an atomic-scale one-dimensional quantum confinement system by single-atom deposition using a controlled point contact is presented. Because of its combined nanofabrication and nanocharacterization capabilities, STM is a powerful tool for exploring the nanotechnology and nanoscience fields. PMID:27877921

  12. Scanning electron microscopy of the endometrium during the secretory phase.

    PubMed Central

    Motta, P M; Andrews, P M

    1976-01-01

    Scanning electron microscopy was used to study the surface morphology of the rabbit endometrium during the secretory phase of the oestrous cycle. The free surfaces of ciliated and of inactive active secretory cells are described. Changes in secretory cell surface morphology resulting from accumulation and secretion of material involve the apparent retraction of microvilli and the formation of one or more bulbous protrusions of the cell's apical surface. These protrusions may be relatively smooth surfaced or exhibit long slender micro-extensions. The protrusions grow in size and are eventually pinched off. Loss of the bulbous protrusions often leaves behind crater-like invaginations of the cell's surface. Secretory cells adjacent to the endometrial glands are the first to exhibit signs of mucin accumulation and secretion. The single cilium of a secretory cell is not apparently affected by the secretory process. Signs of ciliated and secretory cell degeneration, and possible sloughing, are also described. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:1033932

  13. Arc Welders' pneumoconiosis: application of advanced scanning electron microscopy.

    PubMed

    Guidotti, T L; Abraham, J L; DeNee, P B; Smith, J R

    1978-01-01

    Study of lung tissue from necropsy of a 58-year-old arc welder with arc welders' pneumoconiosis, confirmed by history, chest radiography, and pathology, demonstrates the versatility and usefulness of new techniques in scanning electron microscopy (SEM). Secondary electron imaging, the most familiar SEM mode, showed heavy cellular infiltrates in alveoli, the interstitium, and within the interstices of loose whorled fibrotic nodules. Backscattered electron imaging, in which contrast is proportional to elemental atomic number, revealed intracellular metal particles not otherwise visible. Microprobe analysis, energy-dispersive x-ray spectrometry, mapped elemeental iron over the particle image and identified traces of silicon in the whorled nodules. Arc welders' pneumoconiosis appears to be more than a benign siderosis resulting from particulate iron deposition. Simultaneous exposure to other components of welding fumes may alter the pathologic picture, inducing a more complicated fibrotic reaction. The more recently developed advanced techniques of SEM are well suited to the study of pneumoconioses and other problems of heterogenous tissue and mixed chemical systems.

  14. Imaging electronic states on topological semimetals using scanning tunneling microscopy

    DOE PAGES

    Gyenis, András; Inoue, Hiroyuki; Jeon, Sangjun; ...

    2016-10-18

    Following the intense studies on topological insulators, significant efforts have recently been devoted to the search for gapless topological systems. These materials not only broaden the topological classification of matter but also provide a condensed matter realization of various relativistic particles and phenomena previously discussed mainly in high energy physics. Weyl semimetals host massless, chiral, low-energy excitations in the bulk electronic band structure, whereas a symmetry protected pair of Weyl fermions gives rise to massless Dirac fermions.Weemployed scanning tunneling microscopy/spectroscopy to explore the behavior of electronic states both on the surface and in the bulk of topological semimetal phases. Bymore » mapping the quasiparticle interference (QPI) and emerging Landau levels at high magnetic field in Dirac semimetals Cd3As2 and Na3Bi, we observed extended Dirac-like bulk electronic bands. QPI imaged on Weyl semimetal TaAs demonstrated the predicted momentum dependent delocalization of Fermi arc surface states in the vicinity of the surface projected Weyl nodes.« less

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

    PubMed

    de Jonge, Niels; Sougrat, Rachid; Northan, Brian M; Pennycook, Stephen J

    2010-02-01

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

  16. Characterization of paired helical filaments by scanning transmission electron microscopy.

    PubMed

    Ksiezak-Reding, Hanna; Wall, Joseph S

    2005-07-01

    Paired helical filaments (PHFs) are abnormal twisted filaments composed of hyperphosphorylated tau protein. They are found in Alzheimer's disease and other neurodegenerative disorders designated as tauopathies. They are a major component of intracellular inclusions known as neurofibrillary tangles (NFTs). The objective of this review is to summarize various structural studies of PHFs in which using scanning transmission electron microscopy (STEM) has been particularly informative. STEM provides shape and mass per unit length measurements important for studying ultrastructural aspects of filaments. These include quantitative comparisons between dispersed and aggregated populations of PHFs as well as comparative studies of PHFs in Alzheimer's disease and other neurodegenerative disorders. Other approaches are also discussed if relevant or complementary to studies using STEM, e.g., application of a novel staining reagent, Nanovan. Our understanding of the PHF structure and the development of PHFs into NFTs is presented from a historical perspective. Others goals are to describe the biochemical and ultrastructural complexity of authentic PHFs, to assess similarities between authentic and synthetic PHFs, and to discuss recent advances in PHF modeling.

  17. Combined scanning transmission electron microscopy tilt- and focal series.

    PubMed

    Dahmen, Tim; Baudoin, Jean-Pierre; Lupini, Andrew R; Kübel, Christian; Slusallek, Philipp; de Jonge, Niels

    2014-04-01

    In this study, a combined tilt- and focal series is proposed as a new recording scheme for high-angle annular dark-field scanning transmission electron microscopy (STEM) tomography. Three-dimensional (3D) data were acquired by mechanically tilting the specimen, and recording a through-focal series at each tilt direction. The sample was a whole-mount macrophage cell with embedded gold nanoparticles. The tilt-focal algebraic reconstruction technique (TF-ART) is introduced as a new algorithm to reconstruct tomograms from such combined tilt- and focal series. The feasibility of TF-ART was demonstrated by 3D reconstruction of the experimental 3D data. The results were compared with a conventional STEM tilt series of a similar sample. The combined tilt- and focal series led to smaller "missing wedge" artifacts, and a higher axial resolution than obtained for the STEM tilt series, thus improving on one of the main issues of tilt series-based electron tomography.

  18. 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.

  19. Mechanical property quantification of endothelial cells using scanning acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Shelke, A.; Brand, S.; Kundu, T.; Bereiter-Hahn, J.; Blase, C.

    2012-04-01

    The mechanical properties of cells reflect dynamic changes of cellular organization which occur during physiologic activities like cell movement, cell volume regulation or cell division. Thus the study of cell mechanical properties can yield important information for understanding these physiologic activities. Endothelial cells form the thin inner lining of blood vessels in the cardiovascular system and are thus exposed to shear stress as well as tensile stress caused by the pulsatile blood flow. Endothelial dysfunction might occur due to reduced resistance to mechanical stress and is an initial step in the development of cardiovascular disease like, e.g., atherosclerosis. Therefore we investigated the mechanical properties of primary human endothelial cells (HUVEC) of different age using scanning acoustic microscopy at 1.2 GHz. The HUVECs are classified as young (tD < 90 h) and old (tD > 90 h) cells depending upon the generation time for the population doubling of the culture (tD). Longitudinal sound velocity and geometrical properties of cells (thickness) were determined using the material signature curve V(z) method for variable culture condition along spatial coordinates. The plane wave technique with normal incidence is assumed to solve two-dimensional wave equation. The size of the cells is modeled using multilayered (solid-fluid) system. The propagation of transversal wave and surface acoustic wave are neglected in soft matter analysis. The biomechanical properties of HUVEC cells are quantified in an age dependent manner.

  20. 3D scanning Hall probe microscopy with 700 nm resolution

    NASA Astrophysics Data System (ADS)

    Dede, M.; Akram, R.; Oral, A.

    2016-10-01

    In this report, we present a three dimensional (3D) imaging of magnetic field vector B → (x,y,z) emanating from the magnetic material surfaces using a scanning Hall probe microscopy (3D-SHPM) down to a 700 nm spatial resolution. The Hall probe is used to measure Bz(x,y) on the specimen surface at different heights with the step size of Δz = 250 nm, as we move away from the surface in z direction, until the field decays to zero. These set of images are then used to get ∂Bz(x,y)/∂x and ∂Bz(x,y)/∂y at different z by numerical differentiation. Using the Maxwell's equations in the source free region, Bx(x,y) and By(x,y) can be calculated by integrating ∂Bz(x,y)/∂x and ∂Bz(x,y)/∂y in the z direction. Alternatively, the gradients can also be measured in the Hall gradiometer configuration directly. The operation of the 3D-SHPM is demonstrated by imaging Bx(x,y), By(x,y) and Bz(x,y) on a hard disk specimen at a 700 nm resolution, using both of these methods at 77 K. The system is capable of operating from 300 K down to 4 K range.

  1. 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.

  2. Metal-silicene interaction studied by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    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.

  3. Histological preparation of developing vestibular otoconia for scanning electron microscopy

    NASA Technical Reports Server (NTRS)

    Huss, D.; Dickman, J. D.

    2003-01-01

    The unique nature of vestibular otoconia as calcium carbonate biominerals makes them particularly susceptible to chemical deformation during histological processing. We fixed and stored otoconia from all three otolith endorgans of embryonic, hatchling and adult Japanese quail in glutaraldehyde containing either phosphate or non-phosphate buffers for varying lengths of time and processed them for scanning electron microscopy. Otoconia from all age groups and otolith endorgans processed in 0.1 M phosphate buffer (pH 7.4) showed abnormal surface morphology when compared to acetone fixed controls. Otoconia processed in 0.1 M sodium cacodylate or HEPES buffered artificial endolymph (pH 7.4) showed normal morphology that was similar to controls. The degree of otoconial deformation was directly related to the time exposed to phosphate buffer. Short duration exposure produced particulate deformations while longer exposures resulted in fused otoconia that formed solid sheets. Otoconial surface deformation and fusing was independent of the glutaraldehyde component of the histological processing. These findings should help vestibular researchers to develop appropriate histological processing protocols in future studies of otoconia.

  4. Surface treatment of feldspathic porcelain: scanning electron microscopy analysis

    PubMed Central

    Valian, Azam

    2014-01-01

    PURPOSE Topographic analysis of treated ceramics provides qualitative information regarding the surface texture affecting the micromechanical retention and locking of resin-ceramics. This study aims to compare the surface microstructure following different surface treatments of feldspathic porcelain. MATERIALS AND METHODS This in-vitro study was conducted on 72 porcelain discs randomly divided into 12 groups (n=6). In 9 groups, feldspathic surfaces were subjected to sandblasting at 2, 3 or 4 bar pressure for 5, 10 or 15 seconds with 50 µm alumina particles at a 5 mm distance. In group 10, 9.5% hydrofluoric acid (HF) gel was applied for 120 seconds. In group 11, specimens were sandblasted at 3 bar pressure for 10 seconds and then conditioned with HF. In group 12, specimens were first treated with HF and then sandblasted at 3 bar pressure for 10 seconds. All specimens were then evaluated under scanning electron microscopy (SEM) at different magnifications. RESULTS SEM images of HF treated specimens revealed deep porosities of variable sizes; whereas, the sandblasted surfaces were more homogenous and had sharper peaks. Increasing the pressure and duration of sandblasting increased the surface roughness. SEM images of the two combined techniques showed that in group 11 (sandblasted first), HF caused deeper porosities; whereas in group 12 (treated with HF first) sandblasting caused irregularities with less homogeneity. CONCLUSION All surface treatments increased the surface area and caused porous surfaces. In groups subjected to HF, the porosities were deeper than those in sandblasted only groups. PMID:25352961

  5. Spectroscopic scanning tunneling microscopy insights into Fe-based superconductors

    NASA Astrophysics Data System (ADS)

    Hoffman, Jennifer E.

    2011-12-01

    In the first three years since the discovery of Fe-based high Tc superconductors, scanning tunneling microscopy (STM) and spectroscopy have shed light on three important questions. First, STM has demonstrated the complexity of the pairing symmetry in Fe-based materials. Phase-sensitive quasiparticle interference (QPI) imaging and low temperature spectroscopy have shown that the pairing order parameter varies from nodal to nodeless s± within a single family, FeTe1-xSex. Second, STM has imaged C4 → C2 symmetry breaking in the electronic states of both parent and superconducting materials. As a local probe, STM is in a strong position to understand the interactions between these broken symmetry states and superconductivity. Finally, STM has been used to image the vortex state, giving insights into the technical problem of vortex pinning, and the fundamental problem of the competing states introduced when superconductivity is locally quenched by a magnetic field. Here we give a pedagogical introduction to STM and QPI imaging, discuss the specific challenges associated with extracting bulk properties from the study of surfaces, and report on progress made in understanding Fe-based superconductors using STM techniques.

  6. Characterization of fragile nanostructures using scanning force microscopy

    NASA Astrophysics Data System (ADS)

    Buss, Michael Richard

    1998-12-01

    The possibility of using scanning force microscopy (SFM) to image monolayer arrays of nanometer diameter gold clusters on flat substrates has been investigated. A major difficulty in SFM studies of supported cluster arrays is the interaction force between the SFM probe and the clusters which results in the clusters moving on the substrate during imaging. The addition of a carbon nanotube to the tip of the SFM probe reduces this interaction force, resulting in stable, tapping mode height images of the supported cluster arrays. However, resolution of individual nanometer-size cluster in an array requires reduction of the endform radius of the nanotubes. In an attempt to reduce the effects of image dilation, the endform shape of the nanotube has been modified by spark etching. Also, metal atoms have been deposited onto the tip endform by sparking the tip of the nanotube by sparking the tip against a metal substrate and by electro-depositing metal onto the tip. Molecular dynamics (MD) simulations using embedded-atom-method (EAM) potentials have been used to model the compression behavior of nanometer-size gold clusters. The simulations examined the behavior of free and supported gold particles compressed with normal and shear forces. These results have been used to explain previously observed descrepencies between the calculated and measured elastic modulus of nanometer-size gold clusters.

  7. Scanning microwave microscopy technique for nanoscale characterization of magnetic materials

    NASA Astrophysics Data System (ADS)

    Joseph, C. H.; Sardi, G. M.; Tuca, S. S.; Gramse, G.; Lucibello, A.; Proietti, E.; Kienberger, F.; Marcelli, R.

    2016-12-01

    In this work, microwave characterization of magnetic materials using the scanning microwave microscopy (SMM) technique is presented. The capabilities of the SMM are employed for analyzing and imaging local magnetic properties of the materials under test at the nanoscale. The analyses are performed by acquiring both amplitude and phase of the reflected microwave signal. The changes in the reflection coefficient S11 are related to the local properties of the material under investigation, and the changes in its magnetic properties have been studied as a function of an external DC magnetic bias. Yttrium iron garnet (YIG) films deposited by RF sputtering and grown by liquid phase epitaxial (LPE) on gadolinium gallium garnet (GGG) substrates and permalloy samples have been characterized. An equivalent electromagnetic transmission line model is discussed for the quantitative analysis of the local magnetic properties. We also observed the hysteretic behavior of the reflection coefficient S11 with an external bias field. The imaging and spectroscopy analysis on the experimental results are evidently indicating the possibilities of measuring local changes in the intrinsic magnetic properties on the surface of the material.

  8. Imaging electronic states on topological semimetals using scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Gyenis, András; Inoue, Hiroyuki; Jeon, Sangjun; Zhou, Brian B.; Feldman, Benjamin E.; Wang, Zhijun; Li, Jian; Jiang, Shan; Gibson, Quinn D.; Kushwaha, Satya K.; Krizan, Jason W.; Ni, Ni; Cava, Robert J.; Bernevig, B. Andrei; Yazdani, Ali

    2016-10-01

    Following the intense studies on topological insulators, significant efforts have recently been devoted to the search for gapless topological systems. These materials not only broaden the topological classification of matter but also provide a condensed matter realization of various relativistic particles and phenomena previously discussed mainly in high energy physics. Weyl semimetals host massless, chiral, low-energy excitations in the bulk electronic band structure, whereas a symmetry protected pair of Weyl fermions gives rise to massless Dirac fermions. We employed scanning tunneling microscopy/spectroscopy to explore the behavior of electronic states both on the surface and in the bulk of topological semimetal phases. By mapping the quasiparticle interference (QPI) and emerging Landau levels at high magnetic field in Dirac semimetals Cd3As2 and Na3Bi, we observed extended Dirac-like bulk electronic bands. QPI imaged on Weyl semimetal TaAs demonstrated the predicted momentum dependent delocalization of Fermi arc surface states in the vicinity of the surface-projected Weyl nodes.

  9. Histological preparation of developing vestibular otoconia for scanning electron microscopy

    NASA Technical Reports Server (NTRS)

    Huss, D.; Dickman, J. D.

    2003-01-01

    The unique nature of vestibular otoconia as calcium carbonate biominerals makes them particularly susceptible to chemical deformation during histological processing. We fixed and stored otoconia from all three otolith endorgans of embryonic, hatchling and adult Japanese quail in glutaraldehyde containing either phosphate or non-phosphate buffers for varying lengths of time and processed them for scanning electron microscopy. Otoconia from all age groups and otolith endorgans processed in 0.1 M phosphate buffer (pH 7.4) showed abnormal surface morphology when compared to acetone fixed controls. Otoconia processed in 0.1 M sodium cacodylate or HEPES buffered artificial endolymph (pH 7.4) showed normal morphology that was similar to controls. The degree of otoconial deformation was directly related to the time exposed to phosphate buffer. Short duration exposure produced particulate deformations while longer exposures resulted in fused otoconia that formed solid sheets. Otoconial surface deformation and fusing was independent of the glutaraldehyde component of the histological processing. These findings should help vestibular researchers to develop appropriate histological processing protocols in future studies of otoconia.

  10. X-ray absorption measurement by scanning capacitance microscopy

    NASA Astrophysics Data System (ADS)

    Ishii, Masashi; Uchihashi, Takayuki

    2003-12-01

    This paper describes a demonstration of scanning capacitance microscopy (SCM) as a technique for measuring X-ray absorption fine structure (XAFS) in what is called the SCM-XAFS method. This method achieves the simultaneous analysis of the electrical and chemical characteristics of surface-trapping centers. In obtaining the XAFS spectrum of trapping centers, the method takes advantage of the fact that the X-ray-induced photoemission of a localized electron leads to a change in capacitance. When the Fermi level corresponds to the trapping level, the photoemission process is sensitively detected. Therefore, a specific trapping center may be selectively observed by controlling the bias. From SCM-XAFS measurements of a GaAs surface, we found that gallium oxide trapping centers capture electrons in the positive bias voltage region. Moreover, experimental findings that resonant intra-transition and resonant scattering of emitted photoelectrons enhance the SCM-XAFS signal at particular X-ray photon energy reveal the local density of states of the gallium oxide and the complex structure of the trapping centers.

  11. Scanning electron microscopy and roughness study of dental composite degradation.

    PubMed

    Soares, Luís Eduardo Silva; Cortez, Louise Ribeiro; Zarur, Raquel de Oliveira; Martin, Airton Abrahão

    2012-04-01

    Our aim was to test the hypothesis that the use of mouthwashes, consumption of soft drinks, as well as the type of light curing unit (LCU), would change the surface roughness (Ra) and morphology of a nanofilled composite resin (Z350® 3M ESPE). Samples (80) were divided into eight groups: Halogen LCU, group 1, saliva (control); group 2, Pepsi Twist®; group 3, Listerine®; group 4, Colgate Plax®; LED LCU, group 5, saliva; group 6, Pepsi Twist®; group 7, Listerine®; group 8, Colgate Plax®. Ra values were measured at baseline, and after 7 and 14 days. One specimen of each group was prepared for scanning electron microscopy analysis after 14 days. The data were subjected to multifactor analysis of variance at a 95% confidence followed by Tukey's honestly significant difference post-hoc test. All the treatments resulted in morphological changes in composite resin surface, and the most significant change was in Pepsi Twist® groups. The samples of G6 had the greatest increase in Ra. The immersion of nanofilled resin in mouthwashes with alcohol and soft drink increases the surface roughness. Polymerization by halogen LCU (reduced light intensity) associated with alcohol contained mouthwash resulted in significant roughness on the composite.

  12. Ultrastructure of exogenous surfactants using cryogenic scanning electron microscopy.

    PubMed

    Banerjee, R; Bellare, J R

    2001-01-01

    Therapy with specialised biomaterials, exogenous surfactants, is known to significantly decrease the mortality rates in Respiratory Distress Syndrome (RDS). Surfactants available commercially vary widely in composition and biophysical properties. The present paper studies the ultrastructure of three exogenous surfactants used for the treatment of Respiratory Distress Syndrome, namely, Survanta, ALEC and Exosurf Neonatal with respect to their ability to form liposomes using cryogenic scanning electron microscopy. Liposomal organisation is more obvious in Exosurf than in Survanta and is most pronounced in ALEC. ALEC forms closed regular liposomes with an onion-ring-like internal bilayer arrangement. Survanta forms open membranous structures with wavy ribbon-like membranes. The complex membrane-like structures seen with Survanta may be due to the interaction of lipids with surfactant-specific proteins present in this surfactant which is derived from natural lung extracts and might indicate superior spreading at the lipid-water interface. Artificial protein-free surfactants (ALEC and Exosurf) did not appear to form these open membranous structures. Further study of the ultrastructure of possible biomaterials as surfactants could help in the development of new, improved artificial protein-free surfactants with open membranous structures that might facilitate spreading at the air-liquid interface of lungs.

  13. Materials characterisation by angle-resolved scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Müller-Caspary, Knut; Oppermann, Oliver; Grieb, Tim; Krause, Florian F.; Rosenauer, Andreas; Schowalter, Marco; Mehrtens, Thorsten; Beyer, Andreas; Volz, Kerstin; Potapov, Pavel

    2016-11-01

    Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaNxAs1‑x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with GexSi1‑x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16–255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering.

  14. Energy-Filtered Scanning Tunneling Microscopy using a Semiconductor Tip

    NASA Astrophysics Data System (ADS)

    Sutter, P.

    2003-12-01

    Semiconductor probe tips are explored as a tool for spectroscopic scanning tunneling microscopy (STM). Sharp tips capable of atomic-resolution STM are obtained by cleaving (001) oriented InAs wafers. Tunneling spectra measured with InAs tips on graphite show clear signatures of the bulk band structure of the tip. The influence of the tip electronic structure on the tunneling probability can be used to achieve energy-filtered imaging in filled-state constant-current STM with cleaved [111]-oriented InAs tips. Energy gaps in the projected bulk band structure of the tip suppress tunneling, so that only sample states not aligned with a gap contribute significantly to the tunneling current. On Si(111)-(7×7), such energy filtering enables state-selective imaging. Dangling bonds localized on different near-surface Si atoms — adatoms and rest atoms — are mapped selectively at different tip-sample bias. Our findings suggest an important role of the bulk band structure of the probe tip in determining the tunneling current in STM, which may be used to develop novel paradigms of spectroscopic imaging at the atomic scale.

  15. Semiquantitative confocal laser scanning microscopy applied to marine invertebrate ecotoxicology.

    PubMed

    Chandler, G Thomas; Volz, David C

    2004-01-01

    Confocal laser scanning microscopy (CLSM) represents a powerful, but largely unexplored ecotoxicologic tool for rapidly assessing in vivo effects of toxicants on marine invertebrate embryo quality and development. We describe here a new semiquantitative CLSM approach for assessing relative yolk quantity in marine invertebrate embryos (harpacticoid copepods) produced by parents reared from hatching to adult in the polycylic aromatic hydrocarbon chrysene. This method is based on fluorogenic labeling of embryo yolk and subsequent statistical analysis of areal pixel intensities over multiple Z-series using a general linear model (GLM)-nested analysis of variance. The fluorescent yolk-labeling method described here was able to detect statistically significant differences in yolk concentrations in marine copepod (Amphiascus tenuiremis) eggs or embryos from females exposed to ultraviolet light and chrysene-contaminated sediments. Yolk intensities in embryos from females cultured throughout their life cycles in clean sediments were statistically identical with or without UV exposure. In contrast, yolk intensities in embryos of females cultured throughout their life cycle in chrysene-contaminated sediments were significantly higher in the non-UV-exposed treatment with chrysene at 2500 ng/g sediment (65.7% higher) and the UV-exposed treatment with chrysene at 500 ng/g sediment (76.6% higher).

  16. Scanning Electrochemical Microscopy of DNA Monolayers Modified with Nile Blue

    PubMed Central

    Gorodetsky, Alon A.; Hammond, William J.; Hill, Michael G.; Slowinski, Krzysztof; Barton, Jacqueline K.

    2009-01-01

    Scanning electrochemical microscopy (SECM) is used to probe long-range charge transport (CT) through DNA monolayers containing the redox-active Nile Blue (NB) intercalator covalently affixed at a specific location in the DNA film. At substrate potentials negative of the formal potential of covalently attached NB, the electrocatalytic reduction of Fe(CN)63− generated at the SECM tip is observed only when NB is located at the DNA/solution interface; for DNA films containing NB in close proximity to the DNA/electrode interface, the electrocatalytic effect is absent. This behavior is consistent with both rapid DNA-mediated CT between the NB intercalator and the gold electrode as well as a rate-limiting electron transfer between NB and the solution phase Fe(CN)63−. The DNA-mediated nature of the catalytic cycle is confirmed through sequence-specific and localized detection of attomoles of TATA-binding protein, a transcription factor that severely distorts DNA upon binding. Importantly, the strategy outlined here is general and allows for the local investigation of the surface characteristics of DNA monolayers both in the absence and in the presence of DNA binding proteins. These experiments highlight the utility of DNA-modified electrodes as versatile platforms for SECM detection schemes that take advantage of CT mediated by the DNA base pair stack. PMID:19053641

  17. Scanning electron microscopy of lung following alpha irradiation

    SciTech Connect

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

    1989-09-01

    Pulmonary aggregation of inhaled {sup 239}PuO{sub 2} particles leads to a cellular evolution of focal inflammation, fibrosis, epithelial dysplasia and lung tumor formation. Female Wistar rats were exposed to an aerosol of high-fired {sup 239}PuO{sub 2} (initial lung burden, 3.9 kBq) and the lungs examined at intervals from 1 day to 700 days after exposure by light and scanning electron microscopy and autoradiography. Peribronchiolar Pu particle aggregation increased with time, resulting in well-defined focal inflammatory lesions after 120 days and fibrotic lesions after 180 days. A generalized hypertrophy and hyperplasia of nonciliated bronchiolar cells was seen at 15 days and type II cell hyperplasia by 30 days after exposure. Focal dysplastic changes in type II alveolar epithelium and terminal nonciliated bronchiolar epithelium preceded carcinoma formation. Alveolar bronchiolarization was first noted at 120 days, squamous metaplasia at 210 days, squamous carcinoma at 270 days and adenocarcinoma at 600 days after exposure.

  18. Bifurcation, chaos, and scan instability in dynamic atomic force microscopy

    SciTech Connect

    Cantrell, John H.; Cantrell, Sean A.

    2016-03-28

    The dynamical motion at any point on the cantilever of an atomic force microscope can be expressed quite generally as a superposition of simple harmonic oscillators corresponding to the vibrational modes allowed by the cantilever shape. Central to the dynamical equations is the representation of the cantilever-sample interaction force as a polynomial expansion with coefficients that account for the interaction force “stiffness,” the cantilever-to-sample energy transfer, and the displacement amplitude of cantilever oscillation. Renormalization of the cantilever beam model shows that for a given cantilever drive frequency cantilever dynamics can be accurately represented by a single nonlinear mass-spring model with frequency-dependent stiffness and damping coefficients [S. A. Cantrell and J. H. Cantrell, J. Appl. Phys. 110, 094314 (2011)]. Application of the Melnikov method to the renormalized dynamical equation is shown to predict a cascade of period doubling bifurcations with increasing cantilever drive force that terminates in chaos. The threshold value of the drive force necessary to initiate bifurcation is shown to depend strongly on the cantilever setpoint and drive frequency, effective damping coefficient, nonlinearity of the cantilever-sample interaction force, and the displacement amplitude of cantilever oscillation. The model predicts the experimentally observed interruptions of the bifurcation cascade for cantilevers of sufficiently large stiffness. Operational factors leading to the loss of image quality in dynamic atomic force microscopy are addressed, and guidelines for optimizing scan stability are proposed using a quantitative analysis based on system dynamical parameters and choice of feedback loop parameter.

  19. 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).

  20. Nanoscale ferroelectric information storage based on scanning nonlinear dielectric microscopy.

    PubMed

    Cho, Yasuo

    2007-01-01

    An investigation of ultrahigh-density ferroelectric data storage based on scanning nonlinear dielectric microscopy (SNDM) is described. For the purpose of obtaining fundamental knowledge on high-density ferroelectric data storage, several experiments on nanodomain formation in a lithium tantalate (LiTaO3) single crystal were conducted. Through domain engineering, a domain dot array with an areal density of 1.5 Tbit/inch2 was formed on congruent LiTaO3 (CLT). Sub-nanosecond (500 psec) domain switching speed also has been achieved. Next, actual information storage is demonstrated at a density of 1 Tbit/inch2. Finally, it is described that application of a very small dc offset voltage is very effective in accelerating the domain switching speed and in stabilizing the reversed nano-domain dots. Applying this offset application technique, we formed a smallest artificial nano-domain single dot of 5.1 nm in diameter and artificial nano-domain dot-array with a memory density of 10.1 Tbit/inch2 and a bit spacing of 8.0 nm, representing the highest memory density for rewritable data storage reported to date.

  1. Materials characterisation by angle-resolved scanning transmission electron microscopy.

    PubMed

    Müller-Caspary, Knut; Oppermann, Oliver; Grieb, Tim; Krause, Florian F; Rosenauer, Andreas; Schowalter, Marco; Mehrtens, Thorsten; Beyer, Andreas; Volz, Kerstin; Potapov, Pavel

    2016-11-16

    Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaNxAs1-x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with GexSi1-x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16-255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering.

  2. Simplifying Electron Beam Channeling in Scanning Transmission Electron Microscopy (STEM).

    PubMed

    Wu, Ryan J; Mittal, Anudha; Odlyzko, Michael L; Mkhoyan, K Andre

    2017-08-01

    Sub-angstrom scanning transmission electron microscopy (STEM) allows quantitative column-by-column analysis of crystalline specimens via annular dark-field images. The intensity of electrons scattered from a particular location in an atomic column depends on the intensity of the electron probe at that location. Electron beam channeling causes oscillations in the STEM probe intensity during specimen propagation, which leads to differences in the beam intensity incident at different depths. Understanding the parameters that control this complex behavior is critical for interpreting experimental STEM results. In this work, theoretical analysis of the STEM probe intensity reveals that intensity oscillations during specimen propagation are regulated by changes in the beam's angular distribution. Three distinct regimes of channeling behavior are observed: the high-atomic-number (Z) regime, in which atomic scattering leads to significant angular redistribution of the beam; the low-Z regime, in which the probe's initial angular distribution controls intensity oscillations; and the intermediate-Z regime, in which the behavior is mixed. These contrasting regimes are shown to exist for a wide range of probe parameters. These results provide a new understanding of the occurrence and consequences of channeling phenomena and conditions under which their influence is strengthened or weakened by characteristics of the electron probe and sample.

  3. Contamination mitigation strategies for scanning transmission electron microscopy.

    PubMed

    Mitchell, D R G

    2015-06-01

    Modern scanning transmission electron microscopy (STEM) enables imaging and microanalysis at very high magnification. In the case of aberration-corrected STEM, atomic resolution is readily achieved. However, the electron fluxes used may be up to three orders of magnitude greater than those typically employed in conventional STEM. Since specimen contamination often increases with electron flux, specimen cleanliness is a critical factor in obtaining meaningful data when carrying out high magnification STEM. A range of different specimen cleaning methods have been applied to a variety of specimen types. The contamination rate has been measured quantitatively to assess the effectiveness of cleaning. The methods studied include: baking, cooling, plasma cleaning, beam showering and UV/ozone exposure. Of the methods tested, beam showering is rapid, experimentally convenient and very effective on a wide range of specimens. Oxidative plasma cleaning is also very effective and can be applied to specimens on carbon support films, albeit with some care. For electron beam-sensitive materials, cooling may be the method of choice. In most cases, preliminary removal of the bulk of the contamination by methods such as baking or plasma cleaning, followed by beam showering, where necessary, can result in a contamination-free specimen suitable for extended atomic scale imaging and analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Methods for topography artifacts compensation in scanning thermal microscopy.

    PubMed

    Martinek, Jan; Klapetek, Petr; Campbell, Anna Charvátová

    2015-08-01

    Thermal conductivity contrast images in scanning thermal microscopy (SThM) are often distorted by artifacts related to local sample topography. This is pronounced on samples with sharp topographic features, on rough samples and while using larger probes, for example, Wollaston wire-based probes. The topography artifacts can be so high that they can even obscure local thermal conductivity variations influencing the measured signal. Three methods for numerically estimating and compensating for topographic artifacts are compared in this paper: a simple approach based on local sample geometry at the probe apex vicinity, a neural network analysis and 3D finite element modeling of the probe-sample interaction. A local topography and an estimated probe shape are used as source data for the calculation in all these techniques; the result is a map of false conductivity contrast signals generated only by sample topography. This map can be then used to remove the topography artifacts from measured data or to estimate the uncertainty of conductivity measurements using SThM. The accuracy of the results and the computational demands of the presented methods are discussed. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  5. Alternating current scanning electrochemical microscopy with simultaneous fast-scan cyclic voltammetry.

    PubMed

    Koch, Jason A; Baur, Melinda B; Woodall, Erica L; Baur, John E

    2012-11-06

    Fast-scan cyclic voltammetry (FSCV) is combined with alternating current scanning electrochemical microscopy (AC-SECM) for simultaneous measurements of impedance and faradaic current. Scan rates of 10-1000 V s(-1) were used for voltammetry, while a high-frequency (100 kHz), low-amplitude (10 mV rms) sine wave was added to the voltammetric waveform for the ac measurement. Both a lock-in amplifier and an analog circuit were used to measure the amplitude of the resultant ac signal. The effect of the added sine wave on the voltammetry at a carbon fiber electrode was investigated and found to have negligible effect. The combined FSCV and ac measurements were used to provide simultaneous chemical and topographical information about a substrate using a single carbon fiber probe. The technique is demonstrated in living cell culture, where cellular respiration and topography were simultaneously imaged without the addition of a redox mediator. This approach promises to be useful for the topographical and multidimensional chemical imaging of substrates.

  6. Quantitative Scanning Transmission Electron Microscopy of Electronic and Nanostructured Materials

    NASA Astrophysics Data System (ADS)

    Yankovich, Andrew B.

    Electronic and nanostructured materials have been investigated using advanced scanning transmission electron microscopy (STEM) techniques. The first topic is the microstructure of Ga and Sb-doped ZnO. Ga-doped ZnO is a candidate transparent conducting oxide material. The microstructure of GZO thin films grown by MBE under different growth conditions and different substrates were examined using various electron microscopy (EM) techniques. The microstructure, prevalent defects, and polarity in these films strongly depend on the growth conditions and substrate. Sb-doped ZnO nanowires have been shown to be the first route to stable p-type ZnO. Using Z-contrast STEM, I have showed that an unusual microstructure of Sb-decorated head-to-head inversion domain boundaries and internal voids contain all the Sb in the nanowires and cause the p-type conduction. InGaN thin films and InGaN / GaN quantum wells (QW) for light emitting diodes are the second topic. Low-dose Z-contrast STEM, PACBED, and EDS on InGaN QW LED structures grown by MOCVD show no evidence for nanoscale composition variations, contradicting previous reports. In addition, a new extended defect in GaN and InGaN was discovered. The defect consists of a faceted pyramid-shaped void that produces a threading dislocation along the [0001] growth direction, and is likely caused by carbon contamination during growth. Non-rigid registration (NRR) and high-precision STEM of nanoparticles is the final topic. NRR is a new image processing technique that corrects distortions arising from the serial nature of STEM acquisition that previously limited the precision of locating atomic columns and counting the number of atoms in images. NRR was used to demonstrate sub-picometer precision in STEM images of single crystal Si and GaN, the best achieved in EM. NRR was used to measure the atomic surface structure of Pt nanoacatalysts and Au nanoparticles, which revealed new bond length variation phenomenon of surface atoms. In

  7. Diffusion of photoacid generators by laser scanning confocal microscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Ping L.; Webber, Stephen E.; Mendenhall, J.; Byers, Jeffrey D.; Chao, Keith K.

    1998-06-01

    Diffusion of the photogenerated acid during the period of time between exposure and development can cause contrast loss and ultimately loss of the latent image. This is especially relevant for chemically amplified photoresists that require a post-exposure baking step, which in turn facilitates acid diffusion due to the high temperature normally employed. It is thus important to develop techniques with good spatial resolution to monitor the photogeneration of acid. More precisely, we need techniques that provide two distinct types of information: spatial resolution on various length scales within the surface layer and also sufficient depth resolution so that one can observe the transition from very surface layer to bulk structure in the polymer blend coated on silicon substrate. Herein laser scanning confocal microscopy is used to evaluate the resist for the first time. We report the use of the confocal microscopy to map the pag/dye distribution in PHS matrices, with both reflectance images and fluorescence images. A laser beam is focused onto a small 3D volume element, termed a voxel. It is typically 200 nm X 200 nm laterally and 800 nm axially. The illuminated voxel is viewed such that only signals emanating from this voxel are detected, i.e., signal from outside the probed voxel is not detected. By adjusting the vertical position of the laser focal point, the voxel can be moved to the designated lateral plane to produce an image. Contrast caused by topology difference between the exposed and unexposed area can be eliminated. Bis-p-butylphenyl iodonium triflat (7% of polyhydroxystyrene) is used as photoacid generators. 5% - 18% (by weight, PHS Mn equals 13 k) resist in PGMEA solution is spin cast onto the treated quartz disk with thickness of 1.4 micrometers , 5 micrometers space/10 micrometers pitch chrome mask is used to generate the pattern with mercury DUV illumination. Fluoresceinamine, the pH-sensitive dye, is also used to enhance the contrast of

  8. Automated Quantitative Rare Earth Elements Mineralogy by Scanning Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Sindern, Sven; Meyer, F. Michael

    2016-09-01

    Increasing industrial demand of rare earth elements (REEs) stems from the central role they play for advanced technologies and the accelerating move away from carbon-based fuels. However, REE production is often hampered by the chemical, mineralogical as well as textural complexity of the ores with a need for better understanding of their salient properties. This is not only essential for in-depth genetic interpretations but also for a robust assessment of ore quality and economic viability. The design of energy and cost-efficient processing of REE ores depends heavily on information about REE element deportment that can be made available employing automated quantitative process mineralogy. Quantitative mineralogy assigns numeric values to compositional and textural properties of mineral matter. Scanning electron microscopy (SEM) combined with a suitable software package for acquisition of backscatter electron and X-ray signals, phase assignment and image analysis is one of the most efficient tools for quantitative mineralogy. The four different SEM-based automated quantitative mineralogy systems, i.e. FEI QEMSCAN and MLA, Tescan TIMA and Zeiss Mineralogic Mining, which are commercially available, are briefly characterized. Using examples of quantitative REE mineralogy, this chapter illustrates capabilities and limitations of automated SEM-based systems. Chemical variability of REE minerals and analytical uncertainty can reduce performance of phase assignment. This is shown for the REE phases parisite and synchysite. In another example from a monazite REE deposit, the quantitative mineralogical parameters surface roughness and mineral association derived from image analysis are applied for automated discrimination of apatite formed in a breakdown reaction of monazite and apatite formed by metamorphism prior to monazite breakdown. SEM-based automated mineralogy fulfils all requirements for characterization of complex unconventional REE ores that will become

  9. Novel scanning force microscopy methods for investigation of transcription complexes

    NASA Astrophysics Data System (ADS)

    Guthold, Martin

    1997-11-01

    Scanning force microscopy (SFM) methods were developed to investigate the structure and the dynamics of E. coli transcription complexes. The described techniques will also be applicable to the study of other protein-nucleic acid complexes. First, the deposition process of DNA molecules onto a mica surface was investigated using polymer chain statistics. Conditions were found in which DNA molecules, and also protein-DNA complexes, are able to equilibrate on the surface. These findings imply that DNA and protein-DNA complexes attain a lowest energy state on the surface, and that meaningful structural information can, therefore, be obtained from the corresponding SFM images. Using these imaging conditions, SFM was then used to investigate various transcription complexes. The structures of crucial intermediates in the transcriptional activation of RNA polymeraseċsigma54 by NtrC were visualized and analyzed. Moreover, a new method was pioneered to identify the position of specific subunits in multi- protein assemblies. In this method, a specific subunit is tagged with a short piece of DNA which renders it easily recognizable in SFM images. This technique was employed to determine the positions of the two α subunits and the βsp/prime subunit in RNA polymerase-DNA complexes. Finally, SFM imaging in liquid was used to investigate the dynamics of the specific and non-specific interactions between RNA polymerase and DNA. Image sequences of an RNA polymerase actively transcribing a DNA template were obtained and analyzed. Image sequences of non-specific complexes were also obtained, and showed the RNA polymerase moving along the DNA in a one- dimensional random walk. The latter experiments provide some of the first direct evidence that RNA polymerase diffuses along DNA to facilitate promoter location. Chapters II, III, V and VI of this dissertation include material which has been previously published with co- authors. The co-authors are acknowledged at the beginning of

  10. 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.

  11. Characterization of humic substances by environmental scanning electron microscopy.

    PubMed

    Redwood, Paul S; Lead, Jamie R; Harrison, Roy M; Jones, Ian P; Stoll, Serge

    2005-04-01

    Environmental scanning electron microscopy (ESEM) is a new technique capable of imaging micron and submicron particles. Here, we have applied it to image and quantify natural aquatic organic matter (standard Suwannee River humic acid, SRHA). Uniquely, we have observed the humic aggregate structures as a function of humidity and pH. Large aggregates of tens of micrometers were observed as the dominant material under all conditions, although much smaller material was also observed. Fractal dimensions (D) were calculated between 1.48 and 1.70, although these values were not statistically different under conditions of low humidity. However, D values calculated at high humidities (85%) during the rehydration phase were significantly lower (1.48+/-0.01) than in the initial dehydration phase (1.69+/-0.01). This hysteresis indicated that full rehydration of the HS was either kinetically slow or irreversible after dehydration. Fractal analysis of ESEM images was also performed to probe the change in aggregate structure as a function of pH. Minimum values were calculated at neutral pHs, rising by 0.1-0.2 at both high and low pHs because of a combination of the physical chemistry of HS and the impacts of the drying regime within the ESEM. Thus, ESEM was an important complementary technique to other analytical methods. At present, ESEM cannot be used to image nonperturbed natural samples. However, the method is an ideal method for probing the changes in colloid structure as function of hydration state and has the potential to perform fully quantitative and nonperturbing analysis of colloidal structure.

  12. Scanning transmission electron microscopy methods for the analysis of nanoparticles.

    PubMed

    Ponce, Arturo; Mejía-Rosales, Sergio; José-Yacamán, Miguel

    2012-01-01

    Here we review the scanning transmission electron microscopy (STEM) characterization technique and STEM imaging methods. We describe applications of STEM for studying inorganic nanoparticles, and other uses of STEM in biological and health sciences and discuss how to interpret STEM results. The STEM imaging mode has certain benefits compared with the broad-beam illumination mode; the main advantage is the collection of the information about the specimen using a high angular annular dark field (HAADF) detector, in which the images registered have different levels of contrast related to the chemical composition of the sample. Another advantage of its use in the analysis of biological samples is its contrast for thick stained sections, since HAADF images of samples with thickness of 100-120 nm have notoriously better contrast than those obtained by other techniques. Combining the HAADF-STEM imaging with the new aberration correction era, the STEM technique reaches a direct way to imaging the atomistic structure and composition of nanostructures at a sub-angstrom resolution. Thus, alloying in metallic nanoparticles is directly resolved at atomic scale by the HAADF-STEM imaging, and the comparison of the STEM images with results from simulations gives a very powerful way of analysis of structure and composition. The use of X-ray energy dispersive spectroscopy attached to the electron microscope for STEM mode is also described. In issues where characterization at the atomic scale of the interaction between metallic nanoparticles and biological systems is needed, all the associated techniques to STEM become powerful tools for the best understanding on how to use these particles in biomedical applications.

  13. Light microscopy and scanning electron microscopy study on microstructure of gallbladder mucosa in pig.

    PubMed

    Prozorowska, Ewelina; Jackowiak, Hanna

    2015-03-01

    The present light microscopy (LM) and scanning electron microscopy (SEM) studies on porcine gallbladder mucosa provide a description of the microstructures of great functional importance such as mucosal folds, the epithelium, glands, and lymphatic nodules. The results showed the regional structural differences of the porcine gallbladder wall. Depending on the part of the gallbladder, three types of mucosal structures were described: simple and branched folds and mucosal crypts. An important structural feature found in the mucosa is connected with the structural variety of type of mucosal folds, which change from simple located in the neck, to most composed, i.e., branched or joined, in the polygonal crypts toward the fundus of the gallbladder. The morphometric analysis showed statistically significantly differences in the form and size of the folds and between the fundus, body, and neck of the gallbladder. Differences in the size of mucosal epithelium are discussed in terms of processes of synthesis and secretion of glycoproteins. Regional, species-specific differences in morphology of mucosal subepithelial glands, i.e., their secretory units and openings, and intensity of mucus secretion were described. Our results on the pig gallbladder show adaptation and/or specialization in particular areas of the mucosa for (1) secretion of mucus in the neck or body of gallbladder and (2) for cyclic volume changes, especially in the fundus of gallbladder. The description of the microstructures of mucosa in the porcine gallbladder could be useful as reference data for numerous experiments on the bile tract in the pig.

  14. Reflective confocal laser scanning microscopy and nonlinear microscopy of cross-linked rabbit cornea

    NASA Astrophysics Data System (ADS)

    Krueger, Alexander; Hovakimyan, Marina; Ramirez, Diego F.; Stachs, Oliver; Guthoff, Rudolf F.; Heisterkamp, Alexander

    2009-07-01

    Cross-linking of the cornea with application of Ribovlavin and UV-A light is an evolving clinical treatment of the eye disease keratoconus. Despite the positive clinical track record of corneal cross-linking, the complex wound healing process after the treatment is still under investigation. In this study an animal model was used to clarify the state of wound healing 5 weeks after treatment. Cross-linked rabbit corneae were imaged with reflective confocal laser scanning and nonlinear microscopy, namely second harmonic imaging microscopy (SHIM) and two-photon excited autofluorescence. First results show that the NAD(P) H-autofluorescence of the corneal keratocytes and their scattering signal still show a signature of the treatment five weeks after the cross-linking procedure. The SHIM signals show the structural morphology of the fibrous collagen sheets in the stroma of the cornea. SHIM detected in the forward direction differs substantially from backward SHIM, but no signature of treatment was found in both detection channels of the SHIM signal.

  15. Engineering and Characterization of Collagen Networks Using Wet Atomic Force Microscopy and Environmental Scanning Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Osborn, Jenna; Coffey, Tonya; Conrad, Brad; Burris, Jennifer; Hester, Brooke

    2014-03-01

    Collagen is an abundant protein and its monomers covalently crosslink to form fibrils which form fibers which contribute to forming macrostructures like tendon or bone. While the contribution is well understood at the macroscopic level, it is not well known at the fibril level. We wish to study the mechanical properties of collagen for networks of collagen fibers that vary in size and density. We present here a method to synthesize collagen networks from monomers and that allows us to vary the density of the networks. By using biotynilated collagen and a surface that is functionalized with avidin, we generate two-dimensional collagen networks across the surface of a silicon wafer. During network synthesis, the incubation time is varied from 30 minutes to 3 hours or temperature is varied from 25°C to 45°C. The two-dimensional collagen network created in the process is characterized using environmental atomic force microscopy (AFM) and scanning electron microscopy (SEM). The network density is measured by the number of strands in one frame using SPIP software. We expect that at body temperature (37°C) and with longer incubation times, the network density should increase.

  16. Nanoscale characterization of polyoxometalate catalysts by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Kaba, Mahmoud Samah

    Polyoxometalates (POMs) are dsp0 early transition metal oxide anion clusters that have found applications in acid and oxidation catalysis, electrode functionalization, and anti-retroviral therapy. Scanning tunneling microscopy (STM) is a powerful surface science technique that was used to determine the structural properties of self-assembled monolayers of POMs, and to probe the electronic properties of individual POM molecules. In our studies, POMs were deposited from aqueous solutions onto graphite surfaces, and the STM operated in ambient conditions gave well-resolved images of the POM-derivatized surfaces, showing highly ordered, two-dimensional surface arrays (corrugations). The shape and periodicity of the corrugations were consistent with the molecular dimensions and structures of POMs as determined by X-ray diffraction. Different coadsorbed species were also imaged in air using STM; the species were distinguished based on differences in shapes and on electronic properties. These results are important steps toward real-space STM imaging of chemical reactions. Tunneling spectroscopy (TS) measurements (current-voltage, or I-V spectra) taken atop the corrugations and compared with the I-V spectra of bare graphite, confirmed that the STM imaged individual POM molecules in monolayer arrays on graphite. The characteristics of the POM monolayers, such as the effects of counter-cation substitution and anion-framework substitution on the ordered arrays, were also examined by STM. The ubiquity of the ordered array formation of these metal oxide clusters suggests that they can be utilized to create well-defined surfaces with more complex chemical functions than one typically encounters in studies of metal and oxide single crystal surfaces. The POM corrugations exhibited localized electronic phenomena, referred to as negative differential resistance (NDR), at specific voltages in their I-V spectra. The NDR voltage in the I-V spectrum was dependent on the identity of the

  17. 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

  18. Near-field scanning optical microscopy investigations of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Dearo, Jessie Ann

    The Near-Field Scanning Optical Microscopy (NSOM) studies of novel, optically active, conjugated polymers are presented. NSOM is a relatively new technique which produces super resolution (˜50--100 nm) optical images simultaneously with topography. The conjugated polymer poly(p-phenylene vinylene) (PPV) and derivatives of PPV are organic semiconductor-like materials with interesting and unique optical properties. Derivatives of PPV have been used in LEDs and have potential in other optoelectronic devices. NSOM provides a tool for investigation of the photoluminescence, absorption/reflection, photo-dynamics and photoconductivity of films of PPV and PPV derivatives on the length scale that these properties are fundamentally defined. The NSOM experiments have revealed mesoscale domains (˜100 nm) of varying photoluminescence emission and average molecular order in drop cast films of PPV. NSOM of stretch-oriented PPV have shown domains of perpendicular molecular orientation with low photoluminescence emission. Near-field photoconductivity experiments of stretch-oriented PPV have correlated the mesoscale topography with the photoconductivity properties of the polymer. NSOM experiments of films of poly(2-methoxy, 5-(2'-(ethyl(hexyloxy)-p-phenylene vinylene) (MEH-PPV) have shown that there is mesoscale spatial inhomogeneity in the photo-oxidation process which reduces photoluminescence emission. NSOM has also been used to create nanoscale photo-patterning in MEH-PPV films. The NSOM experiments of blended films of MEH-PPV in polystyrene have shown mesoscale phase separation directly correlated to variations in the optical properties of the film. Derivatives of PPV, stretch-oriented in polyethylene, show photoluminescence intensity variations perpendicular and parallel to the stretch-direction correlated to topography features. As a complement to the NSOM studies of conjugated polymers, single polymer molecule experiments of MEH-PPV are also presented. The

  19. 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

  20. Scanning Tunneling Microscopy and Spectroscopy of Silicon and Carbon Surfaces

    NASA Astrophysics Data System (ADS)

    Baker, Shenda Mary

    1992-01-01

    Scanning Tunneling Microscopy (STM) investigations and additional surface analyses were performed on carbon and silicon surfaces. A number of anomalies have been observed on highly oriented pyrolytic graphite (HOPG), including large corrugations, distorted images, large range of tip motion and the absence of defects. A mechanism involving direct contact between tip and sample or contact through a contamination layer to provide an additional conducting pathway is proposed. This model of point-contact imaging provides an explanation for added stability of the STM system, a mechanism for producing multiple tips or sliding graphite planes and an explanation for the observed anomalies. These observations indicate that the use of HOPG for testing and calibration of STM instrumentation may be misleading. Designs for the atmospheric STM used in this study are also presented. The conditions necessary for preparing a clean silicon(111) (7x7) surface are discussed. The design and analysis of heaters necessary to prepare the silicon reconstructed surface at ultrahigh vacuum (UHV) are described. Results from both radiatively and resistively heated samples are shown in addition to a comparison of topographic and barrier height images of the boron (surd 3 times surd 3) reconstructed surfaces. A spectroscopic distinction between sites of boron, silicon or contaminants is demonstrated. A synthetic boron-doped diamond was examined by a number of analytical techniques in order to determine its composition and surface morphology. Current-voltage spectroscopy taken with the STM indicates that the diamond Fermi level can be pinned in atmospheric conditions. In ultrahigh vacuum, band bending is observed, but the strength of the electric field experienced by the diamond semiconductor is less than expected; introduction of surface charges is shown to account for the field screening. Presentation of an STM study of a protein-antibody complex on a gold surface illustrates the requirements

  1. Photoemission electron microscopy and scanning electron microscopy of Magnetospirillum magnetotacticum’s magnetosome chains

    SciTech Connect

    Keutner, Christoph; von Bohlen, Alex; Berges, Ulf; Espeter, Philipp; Schneider, Claus M.; Westphal, Carsten

    2014-10-07

    Magnetotactic bacteria are of great interdisciplinary interest, since a vast field of applications from magnetic recording media to medical nanorobots is conceivable. A key feature for a further understanding is the detailed knowledge about the magnetosome chain within the bacteria. We report on two preparation procedures suitable for UHV experiments in reflective geometry. Further, we present the results of scanning electron microscopy, as well as the first photoemission electron microscopy experiments, both accessing the magnetosomes within intact magnetotactic bacteria and compare these to scanning electron microscopy data from the literature. From the images, we can clearly identify individual magnetosomes within their chains.

  2. Characterization of protein immobilization on nanoporous gold using atomic force microscopy and scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Tan, Yih Horng; Schallom, John R.; Ganesh, N. Vijaya; Fujikawa, Kohki; Demchenko, Alexei V.; Stine, Keith J.

    2011-08-01

    Nanoporous gold (NPG), made by dealloying low carat gold alloys, is a relatively new nanomaterial finding application in catalysis, sensing, and as a support for biomolecules. NPG has attracted considerable interest due to its open bicontinuous structure, high surface-to-volume ratio, tunable porosity, chemical stability and biocompatibility. NPG also has the attractive feature of being able to be modified by self-assembled monolayers. Here we use scanning electron microscopy (SEM) and atomic force microscopy (AFM) to characterize a highly efficient approach for protein immobilization on NPG using N-hydroxysuccinimide (NHS) ester functionalized self-assembled monolayers on NPG with pore sizes in the range of tens of nanometres. Comparison of coupling under static versus flow conditions suggests that BSA (Bovine Serum Albumin) and IgG (Immunoglobulin G) can only be immobilized onto the interior surfaces of free standing NPG monoliths with good coverage under flow conditions. AFM is used to examine protein coverage on both the exterior and interior of protein modified NPG. Access to the interior surface of NPG for AFM imaging is achieved using a special procedure for cleaving NPG. AFM is also used to examine BSA immobilized on rough gold surfaces as a comparative study. In principle, the general approach described should be applicable to many enzymes, proteins and protein complexes since both pore sizes and functional groups present on the NPG surfaces are controllable.Nanoporous gold (NPG), made by dealloying low carat gold alloys, is a relatively new nanomaterial finding application in catalysis, sensing, and as a support for biomolecules. NPG has attracted considerable interest due to its open bicontinuous structure, high surface-to-volume ratio, tunable porosity, chemical stability and biocompatibility. NPG also has the attractive feature of being able to be modified by self-assembled monolayers. Here we use scanning electron microscopy (SEM) and atomic force

  3. Optical axial scanning in confocal microscopy using an electrically tunable lens.

    PubMed

    Jabbour, Joey M; Malik, Bilal H; Olsovsky, Cory; Cuenca, Rodrigo; Cheng, Shuna; Jo, Javier A; Cheng, Yi-Shing Lisa; Wright, John M; Maitland, Kristen C

    2014-02-01

    This paper presents the use and characterization of an electrically focus tunable lens to perform axial scanning in a confocal microscope. Lateral and axial resolution are characterized over a >250 µm axial scan range. Confocal microscopy using optical axial scanning is demonstrated in epithelial tissue and compared to traditional stage scanning. By enabling rapid axial scanning, minimizing motion artifacts, and reducing mechanical complexity, this technique has potential to enhance in vivo three-dimensional imaging in confocal endomicroscopy.

  4. Three-dimensional microscopy by optical scanning holography

    NASA Astrophysics Data System (ADS)

    Poon, Ting-Chung; Doh, Kyu B.; Schilling, Bradley W.; Wu, Ming H.; Shinoda, Kazunori K.; Suzuki, Yoshiji

    1995-05-01

    We first briefly review a new 3D imaging technique called optical scanning holography (OSH). We then discuss the technique's 3D holographic magnification in the context of optical scanning and digital reconstruction. Finally, we demonstrate the 3D imaging capability of OSH by holographically recording two planar objects at different depths and reconstructing the hologram digitally.

  5. Application of scanning electrochemical microscopy to biological samples.

    PubMed Central

    Lee, C; Kwak, J; Bard, A J

    1990-01-01

    The scanning electrochemical microscope can be used in the feedback mode in two-dimensional scans over biological substrates to obtain topographic information at the micrometer level. In this mode, the effect of distance between a substrate (either conductive or insulating) and a scanning ultramicroelectrode tip on the electrolytic current flowing at the tip is recorded as a function of the tip x-y position. Scans of the upper surface of a grass leaf and the lower surface of a Ligustrum sinensis leaf (which show open stomata structures) immersed in aqueous solution are shown. Scans of the upper surface of an elodea leaf in the dark and under irradiation, where the tip reaction is the reduction of oxygen produced by photosynthesis, demonstrate the possibility of obtaining information about the distribution of reaction sites on the substrate surface. Images PMID:2308933

  6. Arbitrary-scan imaging for two-photon microscopy

    NASA Astrophysics Data System (ADS)

    Botcherby, Edward; Smith, Christopher; Booth, Martin; Juskaitis, Rimas; Wilson, Tony

    2010-02-01

    In this paper, we present details of a scanning two-photon fluorescence microscope we have built with a nearisotropic scan rate. This means that the focal spot can be scanned at high speed along any direction in the specimen, without introducing systematic aberrations. We present experimental point spread function measurements for this system using an Olympus 0.8 NA 40X water dipping objective lens that demonstrates an axial range of operation greater than 200 μm. We give details of a novel actuator device used to displace the focusing element and demonstrate axial scan responses up to 3.5 kHz. Finally, we present a bioscience application of this system to image dendritic processes that follow non-linear paths in three-dimensional space. The focal spot was scanned along one such process at 400 Hz with an axial range of more than 90 μm.

  7. Application of Scanning Electrochemical Microscopy to Biological Samples

    NASA Astrophysics Data System (ADS)

    Lee, Chongmok; Kwak, Juhyoun; Bard, Allen J.

    1990-03-01

    The scanning electrochemical microscope can be used in the feedback mode in two-dimensional scans over biological substrates to obtain topographic information at the micrometer level. In this mode, the effect of distance between a substrate (either conductive or insulating) and a scanning ultramicroelectrode tip on the electrolytic current flowing at the tip is recorded as a function of the tip x-y position. Scans of the upper surface of a grass leaf and the lower surface of a Ligustrum sinensis leaf (which show open stomata structures) immersed in aqueous solution are shown. Scans of the upper surface of an elodea leaf in the dark and under irradiation, where the tip reaction is the reduction of oxygen produced by photosynthesis, demonstrate the possibility of obtaining information about the distribution of reaction sites on the substrate surface.

  8. Atomic scale contact formation: A combined Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM) study

    NASA Astrophysics Data System (ADS)

    Hagedorn, Till; El Ouali, Mehdi; Miyahara, Yoichi; Grütter, Peter

    2008-03-01

    We are investigating contact formation at the atomic scale, in particular the interplay of forces and conductivity [1]. As it has been shown (e.g. in the case of C60 in between a STM tip and an Au(111) sample [2]), the conductivity in molecular junctions depends strongly on the contact geometry. In order to fully characterize the junction, we use a homebuilt ultra high vacuum (UHV) (p < 10-10 mbar) microscope which runs in simultaneous scanning tunneling microscope (STM) and atomic force microscope (AFM) modes. Additionally we image the STM tip structure with field ion microscopy (FIM) prior to using it in our experiments [3]. In order to realize a controlled contact we use the STM tip as one electrode and the sample as counter electrode. We are investigating bare Au(111) samples and W STM tips as an example of a nano metal-metal contact and one C60 molecule sandwiched between the W-tip and the Au(111) sample as a model for a controlled metal-molecule-metal contact. We will present new measurements of I(z), F(z) and dI/dV (z) curves of the above mentioned systems, where z is the tip-sample separation as well as images of the sample and tip structure. [1] Sun et. al. PRB 71 193407, 2005 [2] De Menech et. al. PRB 73, 155407, 2006 [3] Lucier et. al. PRB 72, 235420, 2005

  9. Visualization of Microbial Biomarkers by Scanning Electron Microscopy

    NASA Technical Reports Server (NTRS)

    Wainwright, Norman R.; Allen, Carlton C.; Child, Alice

    2001-01-01

    . Fortunately, many antimicrobial defense systems of higher organisms require sensitive detection to combat microbial pathogens. We employ here the primitive immune system of the evolutionarily ancient horseshoe crab, Limulus polyphemus. This species relies on multi-enzyme signal amplification detection of cell wall molecules and they can be applied to the development of useful detectors of life. An extension of this work includes the visualization of microbial signatures by labeling LAL components with chromogenic or electron dense markers. The protein Limulus Anti-LPS Factor (LALF) has an extremely high affinity for LPS. By coupling LALF binding with colloidal gold labels we demonstrate a correlation of the structures visible by electron microscopy with biochemical evidence of microbial cell wall materials. Pure silica particles were mixed with cultures of E. coli (10(exp 6) cfu/mL). Samples were washed sequentially with buffered saline, LALF, antibody to LALF and finally colloidal gold-labeled Protein A. Negative controls were not exposed to E. coli but received identical treatment otherwise. Samples were coated with carbon and imaged on a JEOL JSM-840 scanning electron microscope with LaB6 source in the back scatter mode with the JEOL annular back scatter detector. 20 nm-scale black spots in this contrast-reversed image originate from electrons back-scattered by gold atoms. Negative controls did not give any signal. Future work will expand application of this technique to soil simulants and mineralized rock samples.

  10. Scanning Tunneling Microscopy Studies of Oxide Surface Structure

    NASA Astrophysics Data System (ADS)

    Novak, David S.

    The structural properties of several oxide and metal/oxide systems have been investigated using scanning tunneling microscopy (STM). Oxide materials find wide use in many very important technological applications, and many of these applications depend on nanometer scale structure of the material. STM provides a unique tool for probing the properties of materials in real-space on the atomic ({~}1A) and nanometer distance scales. Oxides are also scientifically interesting for the wide range of physical properties that they exhibit. In these investigations we have studied the surface structure of the metallic oxide Rb _{0.3}MoO_3, the wide band gap semiconductor TiO_2(110), and metal thin films of copper on TiO_2 (110). Much of this research was performed with a UHV STM system which was built in-house at Rutgers. The design and construction of this UHV STM system, including the STM scanners and control electronics, is described in this dissertation. We have prepared nearly perfect TiO_2 (110) (1 x 1) surfaces which are observed with STM to be atomically flat over large areas. The atomic scale structure of the (1 x 1) surface has been successfully imaged with the STM, and the periodicity found in the images is consistent with the bulk truncated (charge neutral) model for the TiO_2(110) (1 x 1) surface. A discussion is given as to whether the STM is imaging the bridging oxygen atom rows (geometric structure dominating) or the five-fold coordinated titanium site (electronic structure dominating). Under certain preparation conditions, a line defect structure is observed on this surface. The defect structure consists of a rowlike feature of approximately 2 A height oriented along the (001). It is believed that these defect rows are the initial steps in the formation of the "high temperature" (1 x 2) phase which has been observed by several groups. A comparison is made between the experimental data and the various models that have been proposed for the defect rows and the

  11. Visualization of Microbial Biomarkers by Scanning Electron Microscopy

    NASA Technical Reports Server (NTRS)

    Wainwright, Norman R.; Allen, Carlton C.; Child, Alice

    2001-01-01

    . Fortunately, many antimicrobial defense systems of higher organisms require sensitive detection to combat microbial pathogens. We employ here the primitive immune system of the evolutionarily ancient horseshoe crab, Limulus polyphemus. This species relies on multi-enzyme signal amplification detection of cell wall molecules and they can be applied to the development of useful detectors of life. An extension of this work includes the visualization of microbial signatures by labeling LAL components with chromogenic or electron dense markers. The protein Limulus Anti-LPS Factor (LALF) has an extremely high affinity for LPS. By coupling LALF binding with colloidal gold labels we demonstrate a correlation of the structures visible by electron microscopy with biochemical evidence of microbial cell wall materials. Pure silica particles were mixed with cultures of E. coli (10(exp 6) cfu/mL). Samples were washed sequentially with buffered saline, LALF, antibody to LALF and finally colloidal gold-labeled Protein A. Negative controls were not exposed to E. coli but received identical treatment otherwise. Samples were coated with carbon and imaged on a JEOL JSM-840 scanning electron microscope with LaB6 source in the back scatter mode with the JEOL annular back scatter detector. 20 nm-scale black spots in this contrast-reversed image originate from electrons back-scattered by gold atoms. Negative controls did not give any signal. Future work will expand application of this technique to soil simulants and mineralized rock samples.

  12. Scanning thermal microscopy with heat conductive nanowire probes.

    PubMed

    Timofeeva, Maria; Bolshakov, Alexey; Tovee, Peter D; Zeze, Dagou A; Dubrovskii, Vladimir G; Kolosov, Oleg V

    2016-03-01

    Scanning thermal microscopy (SThM), which enables measurement of thermal transport and temperature distribution in devices and materials with nanoscale resolution is rapidly becoming a key approach in resolving heat dissipation problems in modern processors and assisting development of new thermoelectric materials. In SThM, the self-heating thermal sensor contacts the sample allowing studying of the temperature distribution and heat transport in nanoscaled materials and devices. The main factors that limit the resolution and sensitivities of SThM measurements are the low efficiency of thermal coupling and the lateral dimensions of the probed area of the surface studied. The thermal conductivity of the sample plays a key role in the sensitivity of SThM measurements. During the SThM measurements of the areas with higher thermal conductivity the heat flux via SThM probe is increased compared to the areas with lower thermal conductivity. For optimal SThM measurements of interfaces between low and high thermal conductivity materials, well defined nanoscale probes with high thermal conductivity at the probe apex are required to achieve a higher quality of the probe-sample thermal contact while preserving the lateral resolution of the system. In this paper, we consider a SThM approach that can help address these complex problems by using high thermal conductivity nanowires (NW) attached to a tip apex. We propose analytical models of such NW-SThM probes and analyse the influence of the contact resistance between the SThM probe and the sample studied. The latter becomes particularly important when both tip and sample surface have high thermal conductivities. These models were complemented by finite element analysis simulations and experimental tests using prototype probe where a multiwall carbon nanotube (MWCNT) is exploited as an excellent example of a high thermal conductivity NW. These results elucidate critical relationships between the performance of the SThM probe on

  13. MEMS-based high speed scanning probe microscopy.

    PubMed

    Disseldorp, E C M; Tabak, F C; Katan, A J; Hesselberth, M B S; Oosterkamp, T H; Frenken, J W M; van Spengen, W M

    2010-04-01

    The high speed performance of a scanning probe microscope (SPM) is improved if a microelectromechanical systems (MEMS) device is employed for the out-of-plane scanning motion. We have carried out experiments with MEMS high-speed z-scanners (189 kHz fundamental resonance frequency) in both atomic force microscope and scanning tunneling microscope modes. The experiments show that with the current MEMS z-scanner, lateral tip speeds of 5 mm/s can be achieved with full feedback on surfaces with significant roughness. The improvement in scan speed, obtained with MEMS scanners, increases the possibilities for SPM observations of dynamic processes. Even higher speed MEMS scanners with fundamental resonance frequencies in excess of a megahertz are currently under development.

  14. Wide field of view multifocal scanning microscopy with sparse sampling

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Wu, Jigang

    2016-02-01

    We propose to use sparsely sampled line scans with a sparsity-based reconstruction method to obtain images in a wide field of view (WFOV) multifocal scanning microscope. In the WFOV microscope, we used a holographically generated irregular focus grid to scan the sample in one dimension and then reconstructed the sample image from line scans by measuring the transmission of the foci through the sample during scanning. The line scans were randomly spaced with average spacing larger than the Nyquist sampling requirement, and the image was recovered with sparsity-based reconstruction techniques. With this scheme, the acquisition data can be significantly reduced and the restriction for equally spaced foci positions can be removed, indicating simpler experimental requirement. We built a prototype system and demonstrated the effectiveness of the reconstruction by recovering microscopic images of a U.S. Air Force target and an onion skin cell microscope slide with 40, 60, and 80% missing data with respect to the Nyquist sampling requirement.

  15. Correlative light and volume electron microscopy: using focused ion beam scanning electron microscopy to image transient events in model organisms.

    PubMed

    Bushby, Andrew J; Mariggi, Giovanni; Armer, Hannah E J; Collinson, Lucy M

    2012-01-01

    The study of a biological event within a live model organism has become routine through the use of fluorescent labeling of specific proteins in conjunction with laser confocal imaging. These methods allow 3D visualization of temporal events that can elucidate biological function but cannot resolve the tissue organization, extracellular and subcellular details of the tissues. Here, we present a method for correlating electron microscopy image data with the light microscopy data from the same sample volume to reveal the 3D structural information: "correlative light and volume electron microscopy." The methods for live video confocal microscopy, fixation and embedding of the tissue for electron microscopy, the focused ion beam scanning electron microscopy method for sequentially slicing and imaging the volume of interest, and the treatment of the resulting 3D dataset are presented. The method is illustrated with data collected during the angiogenesis of blood vessels in a transgenic zebrafish embryo. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Real-time high dynamic range laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Vinegoni, C.; Leon Swisher, C.; Fumene Feruglio, P.; Giedt, R. J.; Rousso, D. L.; Stapleton, S.; Weissleder, R.

    2016-04-01

    In conventional confocal/multiphoton fluorescence microscopy, images are typically acquired under ideal settings and after extensive optimization of parameters for a given structure or feature, often resulting in information loss from other image attributes. To overcome the problem of selective data display, we developed a new method that extends the imaging dynamic range in optical microscopy and improves the signal-to-noise ratio. Here we demonstrate how real-time and sequential high dynamic range microscopy facilitates automated three-dimensional neural segmentation. We address reconstruction and segmentation performance on samples with different size, anatomy and complexity. Finally, in vivo real-time high dynamic range imaging is also demonstrated, making the technique particularly relevant for longitudinal imaging in the presence of physiological motion and/or for quantification of in vivo fast tracer kinetics during functional imaging.

  17. Real-time high dynamic range laser scanning microscopy

    PubMed Central

    Vinegoni, C.; Leon Swisher, C.; Fumene Feruglio, P.; Giedt, R. J.; Rousso, D. L.; Stapleton, S.; Weissleder, R.

    2016-01-01

    In conventional confocal/multiphoton fluorescence microscopy, images are typically acquired under ideal settings and after extensive optimization of parameters for a given structure or feature, often resulting in information loss from other image attributes. To overcome the problem of selective data display, we developed a new method that extends the imaging dynamic range in optical microscopy and improves the signal-to-noise ratio. Here we demonstrate how real-time and sequential high dynamic range microscopy facilitates automated three-dimensional neural segmentation. We address reconstruction and segmentation performance on samples with different size, anatomy and complexity. Finally, in vivo real-time high dynamic range imaging is also demonstrated, making the technique particularly relevant for longitudinal imaging in the presence of physiological motion and/or for quantification of in vivo fast tracer kinetics during functional imaging. PMID:27032979

  18. Cytogenetic Characterization of the TM4 Mouse Sertoli Cell Line. II. Chromosome Microdissection, FISH, Scanning Electron Microscopy, and Confocal Laser Scanning Microscopy.

    PubMed

    Schmid, Michael; Guttenbach, Martina; Steinlein, Claus; Wanner, Gerhard; Houben, Andreas

    2015-01-01

    The chromosomes and interphase cell nuclei of the permanent mouse Sertoli cell line TM4 were examined by chromosome microdissection, FISH, scanning electron microscopy, and confocal laser scanning microscopy. The already known marker chromosomes m1-m5 were confirmed, and 2 new large marker chromosomes m6 and m7 were characterized. The minute heterochromatic marker chromosomes m4 and m5 were microdissected and their DNA amplified by DOP-PCR. FISH of this DNA probe on TM4 metaphase chromosomes demonstrated that the m4 and m5 marker chromosomes have derived from the centromeric regions of normal telocentric mouse chromosomes. Ectopic pairing of the m4 and m5 marker chromosomes with the centromeric region of any of the other chromosomes (centromeric associations) was apparent in ∼60% of the metaphases. Scanning electron microscopy revealed DNA-protein bridges connecting the centromeric regions of normal chromosomes and the associated m4 and m5 marker chromosomes. Interphase cell nuclei of TM4 Sertoli cells did not exhibit the characteristic morphology of Sertoli cells in the testes of adult mice as shown by fluorescence microscopy and confocal laser scanning microscopy.

  19. Scanning probe microscopy study of microcells from the organ surface Bonghan corpuscle

    NASA Astrophysics Data System (ADS)

    Kwon, Joonhyung; Baik, Ku Youn; Lee, Byung-Cheon; Soh, Kwang-Sup; Lee, Nam Joo; Kang, Chi Jung

    2007-04-01

    Microcells from organ surface Bonghan corpuscles [B. H. Kim, J. Acad. Med. Sci. DPR Kor. 90, 1 (1963)] of mammals have been studied by using optical microscopy, transmission electron microscopy and immunohistochemistry. In order to further investigate their physical and electrical properties at better resolution, many different modes of scanning probe microscopy were used in this research. Their surface morphology was studied by topography imaging and error-signal imaging of atomic force microscopy and their mechanical properties were investigated by force modulation microscopy. Electrostatic force microscopy was also used for their electrical characterization.

  20. Fiber-top and ferrule-top cantilevers for atomic force microscopy and scanning near field optical microscopy

    NASA Astrophysics Data System (ADS)

    Chavan, Dhwajal; Gruca, Grzegorz; van de Watering, Tomek; Heeck, Kier; Rector, Jan; Slaman, Martin; Andres, Dieter; Tiribilli, Bruno; Margheri, Giancarlo; Iannuzzi, Davide

    2012-04-01

    Fiber-top and ferrule-top cantilevers (FTC) are a new generation of all optical, monolithic, self-aligned microdevices. They are obtained by carving a cantilever on the cleaved end of an optical fiber (fiber-top) or on a ferrule terminated fiber (ferrule-top). FTCs rely on Fabry-Perot interferometry to measure the deflection of the cantilever with subnanometer deflection sensitivity. FTCs specially developed for scanning probe microscopy are equipped with a sharp tip that has the dual function of probing the topography and collecting/emitting light. We perform the scanning probe microscopy using these probes in air, liquid and at low temperature (12°K). The light emission/collection functionality of FTC probes also allows one to combine scanning near field optical microscopy (SNOM) and optical transmission microscopy with contact and non-contact mode atomic force microscopy (AFM). This makes FTCs ideal for AFM+SNOM on soft samples, polymers and biological specimen, where bent fiber probes and tuning fork based systems would not be recommended because of the high stiffness of those probes. We demonstrate here the capability of fiber-top cantilevers to measure deflection and collect near field optical signal, and also the capability of ferrule-top cantilevers for simultaneous optical transmission microscopy and topography of SNOM gratings. Thanks to their unique features, FTCs also open up possibilities for UV nanolithography and on-demand optical excitation at nanoscale.

  1. Scanning Probe Microscopy of DNA with a Quartz Tuning Fork

    NASA Astrophysics Data System (ADS)

    King, G. M.; Nunes, G., Jr.

    2001-03-01

    Quartz tuning-forks have recently been put to use as highly sensitive force detectors in atomic force microscopy (AFM).(F.J.Giessibl et al.), Science 289, 422 (2000). In this study we have applied a home-built, tuning-fork based AFM to the investigation of single and double stranded DNA (ssDNA and dsDNA). We operate the microscope in the non-contact mode (typical tip amplitude ~1 nm) with a variety of tips (e.g. Si, Si_3N_4, W). Here we report on recent results showing that the apparent height of plasmid dsDNA on mica substrates depends on both the tip material and imaging frequency shift. This talk will also review our efforts to probe ssDNA with a chemically functionalized tip. Current and future prospects for this dynamic-mode, chemically-sensitive force microscopy technique will be discussed.

  2. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    SciTech Connect

    Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

    2016-05-23

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. In this paper, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. Finally, however, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

  3. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    DOE PAGES

    Jesse, S.; Chi, M.; Belianinov, A.; ...

    2016-05-23

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. In this paper, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature andmore » does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. Finally, however, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.« less

  4. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography.

    PubMed

    Jesse, S; Chi, M; Belianinov, A; Beekman, C; Kalinin, S V; Borisevich, A Y; Lupini, A R

    2016-05-23

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called "big-data" methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

  5. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    NASA Astrophysics Data System (ADS)

    Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

    2016-05-01

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

  6. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    PubMed Central

    Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

    2016-01-01

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy. PMID:27211523

  7. The use of laser scanning confocal microscopy (LSCM) in materials science.

    PubMed

    Hovis, D B; Heuer, A H

    2010-12-01

    Laser scanning confocal microscopes are essential and ubiquitous tools in the biological, biochemical and biomedical sciences, and play a similar role to scanning electron microscopes in materials science. However, modern laser scanning confocal microscopes have a number of advantages for the study of materials, in addition to their obvious uses for high resolution reflected and transmitted light optical microscopy. In this paper, we provide several examples that exploit the laser scanning confocal microscope's capabilities of pseudo-infinite depth of field imaging, topographic imaging, photo-stimulated luminescence imaging and Raman spectroscopic imaging. © 2010 The Authors Journal of Microscopy © 2010 The Royal Microscopical Society.

  8. Adaptive probe trajectory scanning probe microscopy for multiresolution measurements of interface geometry

    SciTech Connect

    Ovchinnikov, Oleg S.; Jesse, Stephen; Kalinin, Sergei V

    2009-01-01

    An adaptive scanning method in scanning probe microscopy (SPM) is developed for studies of surfaces with a highly-non-uniform information density such as nanowires or interfaces in disordered media. In path-engineered SPM, the surface is pre-scanned to locate features, and a secondary scan is acquired with the pixel density concentrated in the vicinity of the objects of interest. Here, we demonstrate this approach for piezoresponse force microscopy, and develop approaches for fractal and self-affine characterization of domain interfaces. The relationship between the variational roughness, structure factor, and correlation functions is established and resolution effects on these parameters are determined

  9. Low voltage scanning electron microscopy of interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Blake, D. F.; Bunch, T. E.; Reilly, T. W.; Brownlee, D. E.

    1987-01-01

    The resolution of available low-voltage SEM (LVSEM) models used in the characterization of interplanetary dust particles (IDPs) is limited by a number of factors including energy spread in the electron source, beam brightness, scanning electron detector geometry, and various lens aberrations. This paper describes an improved model of LVSEM which offers an increased resolution at low voltage. The improvements include a cold cathode FE source which has an extremely low inherent energy spread and high brightness, a second condenser lens to converge the beam and maintain an optimum aperture half-angle, and a detector optimized for low-voltage scanning-electron collection. To reduce lens aberrations, the specimen is immersed in the objective lens field. The features of several IDP samples observed using the images obtained with this LVSEM model are described.

  10. Scanning Tunneling Microscopy of Multilayer Thin Film Solar Cell Materials^*

    NASA Astrophysics Data System (ADS)

    Mantovani, J. G.; Friedfeld, R.; Raffaelle, R. P.

    1996-03-01

    We have been investigating electrochemically deposited multilayer structures based on the Cu_xIn_2-xSe2 system for use in thin film solar cells. The interest in multilayer structures is due to their proposed use in increasing thin film solar cell efficiency. We have imaged the artificially imposed superstructure of our nanoscale multilayers using a scanning tunneling microscope. A comparison is made between the theoretically calculated modulation wavelengths and those generated by Fourier analysis of the scanning tunneling microscope images. A discussion of the use of photo-assisted tunneling spectroscopy in a modified STM is presented. * This work was supported by the Southeastern University Research Association in collaboration with Oak Ridge National Laboratory and the Florida Solar Energy Center.

  11. Low voltage scanning electron microscopy of interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Blake, D. F.; Bunch, T. E.; Reilly, T. W.; Brownlee, D. E.

    1987-01-01

    The resolution of available low-voltage SEM (LVSEM) models used in the characterization of interplanetary dust particles (IDPs) is limited by a number of factors including energy spread in the electron source, beam brightness, scanning electron detector geometry, and various lens aberrations. This paper describes an improved model of LVSEM which offers an increased resolution at low voltage. The improvements include a cold cathode FE source which has an extremely low inherent energy spread and high brightness, a second condenser lens to converge the beam and maintain an optimum aperture half-angle, and a detector optimized for low-voltage scanning-electron collection. To reduce lens aberrations, the specimen is immersed in the objective lens field. The features of several IDP samples observed using the images obtained with this LVSEM model are described.

  12. Scanning SQUID microscopy in a cryogen-free refrigerator

    NASA Astrophysics Data System (ADS)

    Schaefer, Brian T.; Low, David; Prawiroatmodjo, Guenevere E. D. K.; Nangoi, J. Kevin; Kim, Jihoon; Nowack, Katja C.

    With helium prices rising and supply becoming increasingly uncertain, it has become attractive to use dry cryostats with cryocoolers rather than liquid helium to reach low temperatures. However, a cryocooler introduces vibrations at the sample stage, making scanning probe experiments more challenging. Here, we report our progress on a superconducting quantum interference device (SQUID) microscope implemented for the first time in a compact, cryogen-free 5 K system. Our microscope is designed to reach submicron spatial resolution and a flux sensitivity of approximately 1 μΦ0 /√{ Hz} , where Φ0 is the magnetic flux quantum. To enable height feedback while approaching and scanning samples, we mount the SQUID on a quartz tuning fork. Our system promises to meet the capabilities of similar systems implemented in helium cryostats.

  13. Scanning electron microscopy of clays and clay minerals

    USGS Publications Warehouse

    Bohor, B.F.; Hughes, R.E.

    1971-01-01

    The scanning electron microscope (SEM) proves to be ideally suited for studying the configuration, texture, and fabric of clay samples. Growth mechanics of crystalline units-interpenetration and interlocking of crystallites, crystal habits, twinning, helical growth, and topotaxis-also are uniquely revealed by the SEM. Authigenic kaolins make up the bulk of the examples because their larger crystallite size, better crystallinity, and open texture make them more suited to examination by the SEM than most other clay mineral types. ?? 1971.

  14. Molecular structure of DNA by scanning tunneling microscopy.

    PubMed

    Cricenti, A; Selci, S; Felici, A C; Generosi, R; Gori, E; Djaczenko, W; Chiarotti, G

    1989-09-15

    Uncoated DNA molecules marked with an activated tris(l-aziridinyl) phosphine oxide (TAPO) solution were deposited on gold substrates and imaged in air with the use of a high-resolution scanning tunneling microscope (STM). Constant-current and gap-modulated STM images show clear evidence of the helicity of the DNA structure: pitch periodicity ranges from 25 to 35 angstroms, whereas the average diameter is 20 angstroms. Molecular structure within a single helix turn was also observed.

  15. Molecular Structure of DNA by Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Cricenti, A.; Selci, S.; Felici, A. C.; Generosi, R.; Gori, E.; Djaczenko, W.; Chiarotti, G.

    1989-09-01

    Uncoated DNA molecules marked with an activated tris(1-aziridinyl) phosphine oxide (TAPO) solution were deposited on gold substrates and imaged in air with the use of a high-resolution scanning tunneling microscope (STM). Constant-current and gap-modulated STM images show clear evidence of the helicity of the DNA structure: pitch periodicity ranges from 25 and 35 angstroms, whereas the average diameter is 20 angstroms. Molecular structure within a single helix turn was also observed.

  16. Direct observations of atomic diffusion by scanning transmission electron microscopy

    PubMed Central

    Isaacson, M.; Kopf, D.; Utlaut, M.; Parker, N. W.; Crewe, A. V.

    1977-01-01

    The feasibility of using a high-resolution scanning transmission electron microscope to study the diffusion of heavy atoms on thin film substrates of low atomic number has been investigated. We have shown that it is possible to visualize the diffusion of individual uranium atoms adsorbed to thin carbon film substrates and that the observed motion of the atoms does not appear to be induced by the incident electron beam. Images PMID:16592396

  17. High-sensitivity SQUIDs with dispersive readout for scanning microscopy

    NASA Astrophysics Data System (ADS)

    Mol, J. M.; Foroughi, F.; Arps, J.; Kammerloher, E.; Bethke, P.; Gibson, G. W., Jr.; Fung, Y. K. K.; Klopfer, B.; Nowack, K.; Kratz, P. A.; Huber, M. E.; Moler, K. A.; Kirtley, J. R.; Bluhm, H.

    2014-03-01

    In a scanning SQUID microscope, the high magnetic flux sensitivity is utilized to image magnetic properties of sample surfaces. As an alternative to the widely used DC SQUIDs, we present Nb SQUIDs for scanning with dispersive microwave readout, featuring significantly higher bandwidth and sensitivity. An on-chip shunt capacitor in parallel with the junction and flux pickup loops forms an LC resonator whose resonance depends on the flux in the SQUID. The readout utilizes a phase-sensitive detection of the reflected drive signal at the SQUID's resonance frequency. Highest sensitivities are achieved by making use of the inherent nonlinearity of the device at high excitation powers. We present a study of the characteristics and noise measurements of our sensors at 4 K. Extrapolations from our results to 300 mK indicate that flux sensitivities as low as 50 nΦ0Hz- 1 / 2 could be possible. Using high-resolution lithography, our sensors promise sub-micron spatial resolution. Integrated into a scanning microscope, they will provide a powerful tool for the study of weak magnetic effects and quantum coherent phenomena. This work was supported by NSF IMR-MIP grant No. 0957616 and the Alfried Krupp von Bohlen und Halbach - Foundation.

  18. Correlative Fluorescence Microscopy and Scanning Transmission Electron Microscopy of Quantum Dot Labeled Proteins in Whole Cells in Liquid

    PubMed Central

    Dukes, Madeline J.; Peckys, Diana B.; de Jonge, Niels

    2010-01-01

    Correlative fluorescence microscopy and transmission electron microscopy (TEM) is a state-of-the-art microscopy methodology to study cellular function, combining the functionality of light microscopy with the high resolution of electron microscopy. However, this technique involves complex sample preparation procedures due to its need for either thin sections or frozen samples for TEM imaging. Here, we introduce a novel correlative approach capable of imaging whole eukaryotic cells in liquid with fluorescence microscopy and with scanning transmission electron microscopy (STEM); there is no additional sample preparation necessary for the electron microscopy. Quantum dots (QDs) were bound to epidermal growth factor (EGF) receptors of COS7 fibroblast cells. Fixed whole cells in saline water were imaged with fluorescence microscopy and subsequently with STEM. The STEM images were correlated with fluorescence images of the same cellular regions. QDs of dimensions 7 × 12 nm were visible in a 5 μm thick layer of saline water, consistent with calculations. A spatial resolution of 3 nm was achieved on the QDs. PMID:20550177

  19. Correlative fluorescence microscopy and scanning transmission electron microscopy of quantum-dot-labeled proteins in whole cells in liquid.

    PubMed

    Dukes, Madeline J; Peckys, Diana B; de Jonge, Niels

    2010-07-27

    Correlative fluorescence microscopy and transmission electron microscopy (TEM) is a state-of-the-art microscopy methodology to study cellular function, combining the functionality of light microscopy with the high resolution of electron microscopy. However, this technique involves complex sample preparation procedures due to its need for either thin sections or frozen samples for TEM imaging. Here, we introduce a novel correlative approach capable of imaging whole eukaryotic cells in liquid with fluorescence microscopy and with scanning transmission electron microscopy (STEM); there is no additional sample preparation necessary for the electron microscopy. Quantum dots (QDs) were bound to epidermal growth factor (EGF) receptors of COS7 fibroblast cells. Fixed whole cells in saline water were imaged with fluorescence microscopy and subsequently with STEM. The STEM images were correlated with fluorescence images of the same cellular regions. QDs of dimensions 7x12 nm were visible in a 5 microm thick layer of saline water, consistent with calculations. A spatial resolution of 3 nm was achieved on the QDs.

  20. Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses

    PubMed Central

    Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David

    2014-01-01

    Background Limbal ring (also known as ‘circle’) contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or ‘enclosed’ within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of ‘circle’ contact lenses. Methods Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. Results SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1 μm below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. Conclusions SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. PMID

  1. Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses.

    PubMed

    Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David

    2014-09-01

    Limbal ring (also known as 'circle') contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or 'enclosed' within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of 'circle' contact lenses. Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1 μm below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. © 2014 The Authors. Clinical and Experimental

  2. Precision controlled atomic resolution scanning transmission electron microscopy using spiral scan pathways

    PubMed Central

    Sang, Xiahan; Lupini, Andrew R.; Ding, Jilai; Kalinin, Sergei V.; Jesse, Stephen; Unocic, Raymond R.

    2017-01-01

    Atomic-resolution imaging in an aberration-corrected scanning transmission electron microscope (STEM) can enable direct correlation between atomic structure and materials functionality. The fast and precise control of the STEM probe is, however, challenging because the true beam location deviates from the assigned location depending on the properties of the deflectors. To reduce these deviations, i.e. image distortions, we use spiral scanning paths, allowing precise control of a sub-Å sized electron probe within an aberration-corrected STEM. Although spiral scanning avoids the sudden changes in the beam location (fly-back distortion) present in conventional raster scans, it is not distortion-free. “Archimedean” spirals, with a constant angular frequency within each scan, are used to determine the characteristic response at different frequencies. We then show that such characteristic functions can be used to correct image distortions present in more complicated constant linear velocity spirals, where the frequency varies within each scan. Through the combined application of constant linear velocity scanning and beam path corrections, spiral scan images are shown to exhibit less scan distortion than conventional raster scan images. The methodology presented here will be useful for in situ STEM imaging at higher temporal resolution and for imaging beam sensitive materials. PMID:28272404

  3. Precision controlled atomic resolution scanning transmission electron microscopy using spiral scan pathways.

    PubMed

    Sang, Xiahan; Lupini, Andrew R; Ding, Jilai; Kalinin, Sergei V; Jesse, Stephen; Unocic, Raymond R

    2017-03-08

    Atomic-resolution imaging in an aberration-corrected scanning transmission electron microscope (STEM) can enable direct correlation between atomic structure and materials functionality. The fast and precise control of the STEM probe is, however, challenging because the true beam location deviates from the assigned location depending on the properties of the deflectors. To reduce these deviations, i.e. image distortions, we use spiral scanning paths, allowing precise control of a sub-Å sized electron probe within an aberration-corrected STEM. Although spiral scanning avoids the sudden changes in the beam location (fly-back distortion) present in conventional raster scans, it is not distortion-free. "Archimedean" spirals, with a constant angular frequency within each scan, are used to determine the characteristic response at different frequencies. We then show that such characteristic functions can be used to correct image distortions present in more complicated constant linear velocity spirals, where the frequency varies within each scan. Through the combined application of constant linear velocity scanning and beam path corrections, spiral scan images are shown to exhibit less scan distortion than conventional raster scan images. The methodology presented here will be useful for in situ STEM imaging at higher temporal resolution and for imaging beam sensitive materials.

  4. Precision controlled atomic resolution scanning transmission electron microscopy using spiral scan pathways

    NASA Astrophysics Data System (ADS)

    Sang, Xiahan; Lupini, Andrew R.; Ding, Jilai; Kalinin, Sergei V.; Jesse, Stephen; Unocic, Raymond R.

    2017-03-01

    Atomic-resolution imaging in an aberration-corrected scanning transmission electron microscope (STEM) can enable direct correlation between atomic structure and materials functionality. The fast and precise control of the STEM probe is, however, challenging because the true beam location deviates from the assigned location depending on the properties of the deflectors. To reduce these deviations, i.e. image distortions, we use spiral scanning paths, allowing precise control of a sub-Å sized electron probe within an aberration-corrected STEM. Although spiral scanning avoids the sudden changes in the beam location (fly-back distortion) present in conventional raster scans, it is not distortion-free. “Archimedean” spirals, with a constant angular frequency within each scan, are used to determine the characteristic response at different frequencies. We then show that such characteristic functions can be used to correct image distortions present in more complicated constant linear velocity spirals, where the frequency varies within each scan. Through the combined application of constant linear velocity scanning and beam path corrections, spiral scan images are shown to exhibit less scan distortion than conventional raster scan images. The methodology presented here will be useful for in situ STEM imaging at higher temporal resolution and for imaging beam sensitive materials.

  5. CONFOCAL LASER SCANNING MICROSCOPY OF APOPTOSIS IN WHOLE MOUSE AND RAT OVARIES

    EPA Science Inventory

    Confocal Laser Scanning Microscopy of Apoptosis in Whole Mouse and Rat Ovaries. Robert M. Zucker Susan C. Jeffay and Sally D. Perreault Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research ...

  6. EVALUATION OF COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY APPLIED TO AN AMBIENT URBAN AEROSOL SAMPLE

    EPA Science Inventory

    Concerns about the environmental and public health effects of particulate matter (PM) have stimulated interest in analytical techniques capable of measuring the size and chemical composition of individual aerosol particles. Computer-controlled scanning electron microscopy (CCSE...

  7. Study on molecular cavity of oligoamide macrocycles by using scanning tunneling microscopy.

    PubMed

    Wang, Yibing; Li, Yibao; Luo, Yin; Xu, Meng; Zhang, Xuemei; Guo, Yuanyuan; Wei, Guanghong; Yuan, Lihua; Gong, Bing; Yang, Yanlian; Wang, Chen

    2012-11-12

    The molecular structures and assembly structures of aromatic oligoamide macrocycles are identified by using scanning tunneling microscopy at liquid/solid interface, which shows persistent shapes, tunable cavity sizes, and binding of water molecules.

  8. EVALUATION OF COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY APPLIED TO AN AMBIENT URBAN AEROSOL SAMPLE

    EPA Science Inventory

    Concerns about the environmental and public health effects of particulate matter (PM) have stimulated interest in analytical techniques capable of measuring the size and chemical composition of individual aerosol particles. Computer-controlled scanning electron microscopy (CCSE...

  9. Gold Coating of Fiber Tips in Near-Field Scanning Optical Microscopy

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.; Witherow, William K.

    2000-01-01

    We report what is believed to be the first experimental demonstration of gold coating by a chemical baking process on tapered fiber tips used in near-field scanning optical microscopy. Many tips can be simultaneously coated.

  10. Gold Coating of Fiber Tips in Near-Field Scanning Optical Microscopy

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.; Witherow, William K.

    2000-01-01

    We report what is believed to be the first experimental demonstration of gold coating by a chemical baking process on tapered fiber tips used in near-field scanning optical microscopy. Many tips can be simultaneously coated.

  11. CONFOCAL LASER SCANNING MICROSCOPY OF APOPTOSIS IN WHOLE MOUSE AND RAT OVARIES

    EPA Science Inventory

    Confocal Laser Scanning Microscopy of Apoptosis in Whole Mouse and Rat Ovaries. Robert M. Zucker Susan C. Jeffay and Sally D. Perreault Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research ...

  12. Hybrid wide-field and scanning microscopy for high-speed 3D imaging.

    PubMed

    Duan, Yubo; Chen, Nanguang

    2015-11-15

    Wide-field optical microscopy is efficient and robust in biological imaging, but it lacks depth sectioning. In contrast, scanning microscopic techniques, such as confocal microscopy and multiphoton microscopy, have been successfully used for three-dimensional (3D) imaging with optical sectioning capability. However, these microscopic techniques are not very suitable for dynamic real-time imaging because they usually take a long time for temporal and spatial scanning. Here, a hybrid imaging technique combining wide-field microscopy and scanning microscopy is proposed to accelerate the image acquisition process while maintaining the 3D optical sectioning capability. The performance was demonstrated by proof-of-concept imaging experiments with fluorescent beads and zebrafish liver.

  13. Dual-wavelength scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Leblanc, Philip R.

    A dual-wavelength Scanning Near-Field Optical Microscope was developed in order to investigate near-field contrast mechanisms as well as biological samples in air. Using a helium-cadmium laser, light of wavelengths 442 and 325 nanometers is coupled into a single mode optical fiber. The end of the probe is tapered to a sub-wavelength aperture, typically 50 nanometers, and positioned in the near-field of the sample. Light from the aperture is transmitted through the sample and detected in a confocal arrangement by two photomultiplier tubes. The microscope has a lateral topographic resolution of 10 nanometers, a vertical resolution of 0.1 nanometer and an optical resolution of 30 nanometers. Two alternate methods of producing the fiber probes, heating and pulling, or acid etching, are compared and the metal coating layer defining the aperture is discussed. So-called "shear-force" interactions between the tip and sample are used as the feedback mechanism during raster scanning of the sample. An optical and topographic sample standard was developed to calibrate the microscope and extract the ultimate resolution of the instrument. The novel use of two wavelengths enables the authentication of true near-field images, as predicted by various models, as well as the identification of scanning artifacts and the deconvolution of often highly complicated relationships between the topographical and optical images. Most importantly, the use of two wavelengths provides information on the chemical composition of the sample. Areas of a polystyrene film are detected by a significant change in the relative transmission of the two wavelengths with a resolution of 30 nanometers. As a biological application, a preliminary investigation of the composition of Black Spruce wood cell fibers was performed. Comparisons of the two optical channels reveal the expected lignin distributions in the cell wall.

  14. Imaging the Predicted Isomerism of Oligo(aniline)s: A Scanning Tunneling Microscopy Study.

    PubMed

    Thomas, James O; Andrade, Hugo D; Mills, Benjamin M; Fox, Neil A; Hoerber, Heinrich J K; Faul, Charl F J

    2015-07-01

    The self-assembly of two emeraldine base tetra(aniline) derivatives is investigated using scanning tunneling microscopy. A combination of the scanning tunneling microscopy data and calculations reveals the presence of predicted cis/trans isomerism in this oxidation state. This isomerism is shown to hinder self-assembly into ordered structures, and provides indications as to why the properties of these materials, and their parent polymer, polyaniline, remain unfulfilled.

  15. [Using of scanning electron microscopy for detection of gunshot residue].

    PubMed

    Havel, J; Vajtr, D; Starý, V; Vrána, J; Zelenka, K; Adámek, T

    2006-07-01

    Scanning electron microscope improves the possibility of investigation of surroundings near of gunshot wounds in forensic medicine, it is the next subsequent method for differentiating of area of entrance and exit wound, supplemental method for determination of firing distance, permit of detection (GSR) on the hand of shooter and ensured describing of samples and their stored. Detection of GSR provides many information about composition of bullet and primer. Authors are demonstrating the possibility of detection of GSR on experimental shooting to the krupon (pigs' skin) in different situation (such as in a room and in outside area) and using of different weapon (hand gun CZ No.75 and machine gun No.58).

  16. 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.

  17. Theory of the laser diode interaction in scanning force microscopy

    SciTech Connect

    Sarid, D.; Iams, D.A.; Ingle, J.T.; Weissenberger, V.

    1989-08-01

    The theory of interaction of a vibrating cantilever and a laser diode used in a scanning force microscope is given in terms of a feedback-dependent parameter C, which determines the gain associated with this interaction. It is shown that both C and the amplitude of vibrations can be determined experimentally from the measurement of the first and second harmonics. Experimental results, which are in good agreement with the theory, yield a value for C which is 0.045. Under these weak feedback conditions, it is found that the interaction can be modeled approximately as a simple homodyne process.

  18. [Scanning electron microscopy of heat-damaged bone tissue].

    PubMed

    Harsanyl, L

    1977-02-01

    Parts of diaphyses of bones were exposed to high temperature of 200-1300 degrees C. Damage to the bone tissue caused by the heat was investigated. The scanning electron microscopic picture seems to be characteristic of the temperature applied. When the bones heated to the high temperature of 700 degrees C characteristic changes appear on the periostal surface, higher temperatura on the other hand causes damage to the compact bone tissue and can be observed on the fracture-surface. Author stresses the importance of this technique in the legal medicine and anthropology.

  19. Time-resolved scanning electron microscopy with polarization analysis

    SciTech Connect

    Frömter, Robert Oepen, Hans Peter; Kloodt, Fabian; Rößler, Stefan; Frauen, Axel; Staeck, Philipp; Cavicchia, Demetrio R.; Bocklage, Lars; Röbisch, Volker; Quandt, Eckhard

    2016-04-04

    We demonstrate the feasibility of investigating periodically driven magnetization dynamics in a scanning electron microscope with polarization analysis based on spin-polarized low-energy electron diffraction. With the present setup, analyzing the time structure of the scattering events, we obtain a temporal resolution of 700 ps, which is demonstrated by means of imaging the field-driven 100 MHz gyration of the vortex in a soft-magnetic FeCoSiB square. Owing to the efficient intrinsic timing scheme, high-quality movies, giving two components of the magnetization simultaneously, can be recorded on the time scale of hours.

  20. Scanning transmission electron microscopy: Albert Crewe's vision and beyond.

    PubMed

    Krivanek, Ondrej L; Chisholm, Matthew F; Murfitt, Matthew F; Dellby, Niklas

    2012-12-01

    Some four decades were needed to catch up with the vision that Albert Crewe and his group had for the scanning transmission electron microscope (STEM) in the nineteen sixties and seventies: attaining 0.5Å resolution, and identifying single atoms spectroscopically. With these goals now attained, STEM developments are turning toward new directions, such as rapid atomic resolution imaging and exploring atomic bonding and electronic properties of samples at atomic resolution. The accomplishments and the future challenges are reviewed and illustrated with practical examples. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. A scanning tunneling microscopy tip with a stable atomic structure

    NASA Astrophysics Data System (ADS)

    Kim, Yeong-Cheol; Seidman, David N.

    2004-02-01

    A single stable adatom on a {110}-type plane of a tungsten tip is created via field-evaporation in a field-ion microscope (FIM) operating at room temperature. This single adatom has sufficient surface mobility at room temperature and migrates, in one-dimension, along a <111>-type direction toward an edge of a {110}-type plane, due to the existence of an electric field gradient. The plane edge has a higher local electric field than its center, since it has a higher local geometric curvature. This result implies that the stable position of a single adatom during a scan of a scanning tunneling microscope (STM) tip on a surface is at the edge and not at the center of a {110}-type plane at room temperature. Therefore, the electron wave function of a tip is not symmetric and this fact should be taken into account in a careful analysis of STM images. Also a tip with a dislocation emerging at a {110}-type plane is suggested as an improved STM tip configuration, as the step at the surface, created by the intersection of the dislocation with it, is a perpetual source of single adatoms.

  2. Automated rapid particle investigation using scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Wilkins, Jerod Laurence

    The chemical composition of fly ash particles has been known to vary significantly depending on a number of factors. Current bulk methods of investigation including X-Ray Fluorescence and X-Ray Diffraction are thought to be inadequate in determining the performance of fly ash in concrete. It is the goal of this research to develop a method of Automated Rapid Particle Investigation that will not look at fly ash as a bulk material but as individual particles. By examining each particle individually scientists and engineers will have the ability to study the variation in chemical composition by comparing the chemistry present in each particle. The method of investigation developed by this research provides a practical technique that will allow the automated chemical analysis of hundreds, or even thousands, of fly ash particles in a matter of minutes upon completion of sample preparation and automated scanning electron microscope (ASEM) scanning. This research does not examine the significance of the chemical compounds discovered; rather, only the investigation methodology is discussed. Further research will be done to examine the importance of the chemistry discovered with this automated rapid particle investigation technique.

  3. Scanning transmission x-ray microscopy of unaltered biological specimens

    SciTech Connect

    Iskander, N.

    1987-05-01

    A scanning transmission x-ray microscope at the National Synchrotron Light Source was used to image fresh, wet biological specimens at 32 Angstroms, with resolution better than 750 Angstroms. A gold Fresnel zone plate (outer zone width 500 Angstroms) was used to focus the undulator radiation, and the sample was scanned through the spot. Absorption data was recorded digitally as a gridded array. The major accomplishment of the experiment was the demonstration of the ability to image biological samples in their natural state with high resolution and natural elemental contrast mechanisms. This was achieved through the design of a sample holder that maintains an aqueous environment for the sample, yet is transparent to x-rays at 32 Angstroms. The specimens used were isolated zymogen granules (approximately 1 micron diameter) from the pancreatic acinar cells of rats. The absorption data were correlated to protein concentration, and estimates of the protein concentrations within the granules were obtained. The data also yields some information about the spatial organization of the protein in the granules, and our data is compared to models for the internal structure. The success of this experiment points toward future opportunities for dynamical studies on living systems. 6 refs., 28 figs., 2 tabs.

  4. A spin rotator for spin-polarized scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Kohashi, Teruo; Konoto, Makoto; Koike, Kazuyuki

    2004-06-01

    A Wien filter, which is a common energy analyzer, was modified as a spin rotator for use in a spin-polarized scanning electron microscope. By switching the spin rotator on and off, magnetic domain images of all three magnetization vectors can be produced in one scan. The electrodes and the magnetic pole pieces were specially designed by using a three-dimensional computer simulation for electric and magnetic fields, electron trajectories, and spin rotation; the broad beam of the secondary electrons passes through to the spin detector with a 90° rotation. The structure is simple with only two electrodes that have hyperbolically curved surfaces to create a stigmatic focusing effect, while the surfaces of the magnetic pole pieces are flat to enable a uniform rotation of all electron spins. The performance was tested and confirmed to be effective by observing the magnetic domain structures of Fe(001) with in-surface-plane magnetization and a TbFeCo magneto-optical medium with surface normal magnetization.

  5. Synthesis and characterization of Copper/Cobalt/Copper/Iron nanostructurated films with magnetoresistive properties

    NASA Astrophysics Data System (ADS)

    Ciupinǎ, Victor; Prioteasa, Iulian; Ilie, Daniela; Manu, Radu; Petrǎşescu, Lucian; Tutun, Ştefan Gabriel; Dincǎ, Paul; MustaÅ£ǎ, Ion; Lungu, Cristian Petricǎ; Jepu, IonuÅ£; Vasile, Eugeniu; Nicolescu, Virginia; Vladoiu, Rodica

    2017-02-01

    Copper/Cobalt/Copper/Iron thin films were synthesized in order to obtain nanostructured materials with special magnetoresistive properties. The multilayer films were deposited on silicon substrates. In this respect we used Thermionic Vacuum Arc Discharge Method (TVA). The benefit of this deposition technique is the ability to have a controlled range of thicknesses starting from few nanometers to hundreds of nanometers. The purity of the thin films was insured by a high vacuum pressure and a lack of any kind of buffer gas inside the coating chamber. The morphology and structure of the thin films were analyzed using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) Techniques and Energy Dispersive X-ray Spectroscopy (EDXS). Magnetoresistive measurement results depict that thin films possess Giant Magneto-Resistance Effect (GMR). Magneto-Optic-Kerr Effect (MOKE) studies were performed to characterize the magnetic properties of these thin films.

  6. Differentiating Ferroelectric and Nonferroelectric Electromechanical Effects with Scanning Probe Microscopy

    DOE PAGES

    Balke, Nina; Maksymovych, Petro; Jesse, Stephen; ...

    2015-06-02

    Ferroelectricity in functional materials remains one of the most fascinating areas of modern science in the past several decades. In the last several years, the rapid development of piezoresponse force microscopy (PFM) and spectroscopy revealed the presence of electromechanical hysteresis loops and bias-induced remnant polar states in a broad variety of materials including many inorganic oxides, polymers, and biosystems. In many cases, this behavior was interpreted as the ample evidence for ferroelectric nature of the system. Here, we systematically analyze PFM responses on ferroelectric and nonferroelectric materials and demonstrate that mechanisms unrelated to ferroelectricity can induce ferroelectric-like characteristics through chargemore » injection and electrostatic forces on the tip. In this paper, we will focus on similarities and differences in various PFM measurement characteristics to provide an experimental guideline to differentiate between ferroelectric material properties and charge injection. In conclusion, we apply the developed measurement protocols to an unknown ferroelectric material.« less

  7. High Resolution Quantitative Angle-Scanning Widefield Surface Plasmon Microscopy

    PubMed Central

    Tan, Han-Min; Pechprasarn, Suejit; Zhang, Jing; Pitter, Mark C.; Somekh, Michael G.

    2016-01-01

    We describe the construction of a prismless widefield surface plasmon microscope; this has been applied to imaging of the interactions of protein and antibodies in aqueous media. The illumination angle of spatially incoherent diffuse laser illumination was controlled with an amplitude spatial light modulator placed in a conjugate back focal plane to allow dynamic control of the illumination angle. Quantitative surface plasmon microscopy images with high spatial resolution were acquired by post-processing a series of images obtained as a function of illumination angle. Experimental results are presented showing spatially and temporally resolved binding of a protein to a ligand. We also show theoretical results calculated by vector diffraction theory that accurately predict the response of the microscope on a spatially varying sample thus allowing proper quantification and interpretation of the experimental results. PMID:26830146

  8. Differentiating Ferroelectric and Nonferroelectric Electromechanical Effects with Scanning Probe Microscopy

    SciTech Connect

    Balke, Nina; Maksymovych, Petro; Jesse, Stephen; Herklotz, Andreas; Tselev, Alexander; Eom, Chang-Beom; Kravchenko, Ivan I.; Yu, Pu; Kalinin, Sergei V.

    2015-06-02

    Ferroelectricity in functional materials remains one of the most fascinating areas of modern science in the past several decades. In the last several years, the rapid development of piezoresponse force microscopy (PFM) and spectroscopy revealed the presence of electromechanical hysteresis loops and bias-induced remnant polar states in a broad variety of materials including many inorganic oxides, polymers, and biosystems. In many cases, this behavior was interpreted as the ample evidence for ferroelectric nature of the system. Here, we systematically analyze PFM responses on ferroelectric and nonferroelectric materials and demonstrate that mechanisms unrelated to ferroelectricity can induce ferroelectric-like characteristics through charge injection and electrostatic forces on the tip. In this paper, we will focus on similarities and differences in various PFM measurement characteristics to provide an experimental guideline to differentiate between ferroelectric material properties and charge injection. In conclusion, we apply the developed measurement protocols to an unknown ferroelectric material.

  9. Electromechanical imaging of biomaterials by scanning probe microscopy.

    PubMed

    Rodriguez, B J; Kalinin, S V; Shin, J; Jesse, S; Grichko, V; Thundat, T; Baddorf, A P; Gruverman, A

    2006-02-01

    The majority of calcified and connective tissues possess complex hierarchical structure spanning the length scales from nanometers to millimeters. Understanding the biological functionality of these materials requires reliable methods for structural imaging on the nanoscale. Here, we demonstrate an approach for electromechanical imaging of the structure of biological samples on the length scales from tens of microns to nanometers using piezoresponse force microscopy (PFM), which utilizes the intrinsic piezoelectricity of biopolymers such as proteins and polysaccharides as the basis for high-resolution imaging. Nanostructural imaging of a variety of protein-based materials, including tooth, antler, and cartilage, is demonstrated. Visualization of protein fibrils with sub-10nm spatial resolution in a human tooth is achieved. Given the near-ubiquitous presence of piezoelectricity in biological systems, PFM is suggested as a versatile tool for micro- and nanostructural imaging in both connective and calcified tissues.

  10. Core/shell nanofiber characterization by Raman scanning microscopy

    PubMed Central

    Sfakis, Lauren; Sharikova, Anna; Tuschel, David; Costa, Felipe Xavier; Larsen, Melinda; Khmaladze, Alexander; Castracane, James

    2017-01-01

    Core/shell nanofibers are becoming increasingly popular for applications in tissue engineering. Nanofibers alone provide surface topography and increased surface area that promote cellular attachment; however, core/shell nanofibers provide the versatility of incorporating two materials with different properties into one. Such synthetic materials can provide the mechanical and degradation properties required to make a construct that mimics in vivo tissue. Many variations of these fibers can be produced. The challenge lies in the ability to characterize and quantify these nanofibers post fabrication. We developed a non-invasive method for the composition characterization and quantification at the nanoscale level of fibers using Confocal Raman microscopy. The biodegradable/biocompatible nanofibers, Poly (glycerol-sebacate)/Poly (lactic-co-glycolic) (PGS/PLGA), were characterized as a part of a fiber scaffold to quickly and efficiently analyze the quality of the substrate used for tissue engineering. PMID:28271000

  11. Electromechanical Imaging of Biomaterials by Scanning Probe Microscopy

    SciTech Connect

    Rodriguez, Brian J; Kalinin, Sergei V; Shin, Junsoo; Jesse, Stephen; Grichko, V.; Thundat, Thomas George; Baddorf, Arthur P; Gruverman, A.

    2006-01-01

    The majority of calcified and connective tissues possess complex hierarchical structure spanning the length scales from nanometers to millimeters. Understanding the biological functionality of these materials requires reliable methods for structural imaging on the nanoscale. Here, we demonstrate an approach for electromechanical imaging of the structure of biological samples on the length scales from tens of microns to nanometers using piezoresponse force microscopy (PFM), which utilizes the intrinsic piezoelectricity of biopolymers such as proteins and polysaccharides as the basis for high-resolution imaging. Nanostructural imaging of a variety of protein-based materials, including tooth, antler, and cartilage, is demonstrated. Visualization of protein fibrils with sub-10 nm spatial resolution in a human tooth is achieved. Given the near-ubiquitous presence of piezoelectricity in biological systems, PFM is suggested as a versatile tool for micro- and nanostructural imaging in both connective and calcified tissues.

  12. Rigorous theory on elliptical mirror focusing for point scanning microscopy.

    PubMed

    Liu, Jian; Tan, Jiubin; Wilson, Tony; Zhong, Cien

    2012-03-12

    A rigorous elliptical mirror focusing formula based on spherical wave transformation is derived as a kind of imaging technique with high NA for potential applications in molecule imaging, spectroscopy and industrial artifact microscopy. An apodization factor is given and used to compare the energy conversation rules in lens transmission and parabolic and elliptical mirror reflections. Simulation results indicate that the axial HFWHM of elliptical and parabolic mirrors is about 80% of the corresponding HFWHM of lens in case of NA = 1 and φs = 0, and the side lobe noise is also slightly lower than that of lens, but the transverse HFWHM of mirrors is comparatively wider despite the width of main lobe is still smaller. In comparison with parabolic mirror based system, an elliptical mirror based system is potentially promising in aberration control of incident beam when the aperture of mirror is enlarged to adapt a large stage or specimen container at a small beam shading ratio.

  13. Scanning Probe Microscopy as a Tool Applied to Agriculture

    NASA Astrophysics Data System (ADS)

    Leite, Fabio Lima; Manzoli, Alexandra; de Herrmann, Paulo Sérgio Paula; Oliveira, Osvaldo Novais; Mattoso, Luiz Henrique Capparelli

    The control of materials properties and processes at the molecular level inherent in nanotechnology has been exploited in many areas of science and technology, including agriculture where nanotech methods are used in release of herbicides and monitoring of food quality and environmental impact. Atomic force microscopy (AFM) and related techniques are among the most employed nanotech methods, particularly with the possibility of direct measurements of intermolecular interactions. This chapter presents a brief review of the applications of AFM in agriculture that may be categorized into four main topics, namely thin films, research on nanomaterials and nanostructures, biological systems and natural fibers, and soils science. Examples of recent applications will be provided to give the reader a sense of the power of the technique and potential contributions to agriculture.

  14. Differentiating Ferroelectric and Nonferroelectric Electromechanical Effects with Scanning Probe Microscopy.

    PubMed

    Balke, Nina; Maksymovych, Petro; Jesse, Stephen; Herklotz, Andreas; Tselev, Alexander; Eom, Chang-Beom; Kravchenko, Ivan I; Yu, Pu; Kalinin, Sergei V

    2015-06-23

    Ferroelectricity in functional materials remains one of the most fascinating areas of modern science in the past several decades. In the last several years, the rapid development of piezoresponse force microscopy (PFM) and spectroscopy revealed the presence of electromechanical hysteresis loops and bias-induced remnant polar states in a broad variety of materials including many inorganic oxides, polymers, and biosystems. In many cases, this behavior was interpreted as the ample evidence for ferroelectric nature of the system. Here, we systematically analyze PFM responses on ferroelectric and nonferroelectric materials and demonstrate that mechanisms unrelated to ferroelectricity can induce ferroelectric-like characteristics through charge injection and electrostatic forces on the tip. We will focus on similarities and differences in various PFM measurement characteristics to provide an experimental guideline to differentiate between ferroelectric material properties and charge injection. In the end, we apply the developed measurement protocols to an unknown ferroelectric material.

  15. Combining scanning probe microscopy and x-ray spectroscopy

    PubMed Central

    2011-01-01

    A new versatile tool, combining Shear Force Microscopy and X-Ray Spectroscopy was designed and constructed to obtain simultaneously surface topography and chemical mapping. Using a sharp optical fiber as microscope probe, it is possible to collect locally the visible luminescence of the sample. Results of tests on ZnO and on ZnWO4 thin layers are in perfect agreement with that obtained with other conventional techniques. Twin images obtained by simultaneous acquisition in near field of surface topography and of local visible light emitted by the sample under X-Ray irradiation in synchrotron environment are shown. Replacing the optical fibre by an X-ray capillary, it is possible to collect local X-ray fluorescence of the sample. Preliminary results on Co-Ti sample analysis are presented. PMID:21711848

  16. Second-harmonic scanning microscopy of domains in Al wire bonds in IGBT modules.

    PubMed

    Simesen, Paw; Pedersen, Kristian Bonderup; Pedersen, Kjeld

    2015-12-28

    Scanning second harmonic generation microscopy has been used to investigate crystallographic orientation of the grain structure in Al wire bonds in insulated gate bipolar transistor modules. It was shown that the recorded second harmonic microscopy images revealed the grain structure of the Al sample. Additional information of the individual grain orientation was achieved by using simple interpretations of the recorded rotational anisotropy.

  17. Band Excitation in Scanning Probe Microscopy: Recognition and Functional Imaging

    SciTech Connect

    Jesse, Stephen; Vasudevan, Dr. Rama; Collins, Liam; Strelcov, Evgheni; Okatan, Mahmut B; Belianinov, Alex; Baddorf, Arthur P; Proksch, Roger; Kalinin, Sergei V

    2014-01-01

    Field confinement at the junction between a biased scanning probe microscope s (SPM) tip and solid surface enables local probing of various bias-induced transformations such as polarization switching, ionic motion, or electrochemical reactions to name a few. The nanoscale size of the biased region is smaller or comparable to features like grain boundaries and dislocations, potentially allows for the study of kinetics and thermodynamics at the level of a single defect. In contrast to classical statistically averaged approaches, this allows one to link structure to functionality and deterministically decipher associated mesoscopic and atomistic mechanisms. Furthermore, this type of information can serve as a fingerprint of local material functionality, allowing for local recognition imaging. Here, current progress in multidimensional SPM techniques based on band-excitation time and voltage spectroscopies is illustrated, including discussions on data acquisition, dimensionality reduction, and visualization along with future challenges and opportunities for the field.

  18. Ferroelectric Switching by the Grounded Scanning Probe Microscopy Tip

    SciTech Connect

    Ievlev, Anton V.; Morozovska, A. N.; Shur, Vladimir Ya.; Kalinin, Sergei V.

    2015-06-19

    The process of polarization reversal by the tip of scanning probe microscope was intensively studied for last two decades. Number of the abnormal switching phenomena was reported by the scientific groups worldwide. In particularly it was experimentally and theoretically shown that slow dynamics of the surface screening controls kinetics of the ferroelectric switching, backswitching and relaxation and presence of the charges carriers on the sample surface and in the sample bulk significantly change polarization reversal dynamics. Here we experimentally demonstrated practical possibility of the history dependent polarization reversal by the grounded SPM tip. This phenomenon was attributed to induction of the slowly dissipating charges into the surface of the grounded tip that enables polarization reversal under the action of the produced electric field. Analytical and numerical electrostatic calculations allow additional insight into nontrivial abnormal switching phenomena reported earlier.

  19. Optimization of the imaging response of scanning microwave microscopy measurements

    SciTech Connect

    Sardi, G. M.; Lucibello, A.; Proietti, E.; Marcelli, R.; Kasper, M.; Gramse, G.; Kienberger, F.

    2015-07-20

    In this work, we present the analytical modeling and preliminary experimental results for the choice of the optimal frequencies when performing amplitude and phase measurements with a scanning microwave microscope. In particular, the analysis is related to the reflection mode operation of the instrument, i.e., the acquisition of the complex reflection coefficient data, usually referred as S{sub 11}. The studied configuration is composed of an atomic force microscope with a microwave matched nanometric cantilever probe tip, connected by a λ/2 coaxial cable resonator to a vector network analyzer. The set-up is provided by Keysight Technologies. As a peculiar result, the optimal frequencies, where the maximum sensitivity is achieved, are different for the amplitude and for the phase signals. The analysis is focused on measurements of dielectric samples, like semiconductor devices, textile pieces, and biological specimens.

  20. Moessbauer spectroscopy and scanning electron microscopy of the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Brown, Christopher L.; Oliver, Frederick W.; Hammond, Ernest C., Jr.

    1989-01-01

    Meteorites provide a wealth of information about the solar system's formation, since they have similar building blocks as the Earth's crust but have been virtually unaltered since their formation. Some stony meteorites contain minerals and silicate inclusions, called chondrules, in the matrix. Utilizing Moessbauer spectroscopy, we identified minerals in the Murchison meteorite, a carbonaceous chondritic meteorite, by the gamma ray resonance lines observed. Absorption patterns of the spectra were found due to the minerals olivine and phyllosilicate. We used a scanning electron microscope to describe the structure of the chondrules in the Murchison meteorite. The chondrules were found to be deformed due to weathering of the meteorite. Diameters varied in size from 0.2 to 0.5 mm. Further enhancement of the microscopic imagery using a digital image processor was used to describe the physical characteristics of the inclusions.

  1. Scanning Hall probe microscopy of a diluted magnetic semiconductor

    SciTech Connect

    Kweon, Seongsoo; Samarth, Nitin; Lozanne, Alex de

    2009-05-01

    We have measured the micromagnetic properties of a diluted magnetic semiconductor as a function of temperature and applied field with a scanning Hall probe microscope built in our laboratory. The design philosophy for this microscope and some details are described. The samples analyzed in this work are Ga{sub 0.94}Mn{sub 0.06}As films grown by molecular beam epitaxy. We find that the magnetic domains are 2-4 mum wide and fairly stable with temperature. Magnetic clusters are observed above T{sub C}, which we ascribe to MnAs defects too small and sparse to be detected by a superconducting quantum interference device magnetometer.

  2. Ferroelectric Switching by the Grounded Scanning Probe Microscopy Tip

    DOE PAGES

    Ievlev, Anton V.; Morozovska, A. N.; Shur, Vladimir Ya.; ...

    2015-06-19

    The process of polarization reversal by the tip of scanning probe microscope was intensively studied for last two decades. Number of the abnormal switching phenomena was reported by the scientific groups worldwide. In particularly it was experimentally and theoretically shown that slow dynamics of the surface screening controls kinetics of the ferroelectric switching, backswitching and relaxation and presence of the charges carriers on the sample surface and in the sample bulk significantly change polarization reversal dynamics. Here we experimentally demonstrated practical possibility of the history dependent polarization reversal by the grounded SPM tip. This phenomenon was attributed to induction ofmore » the slowly dissipating charges into the surface of the grounded tip that enables polarization reversal under the action of the produced electric field. Analytical and numerical electrostatic calculations allow additional insight into nontrivial abnormal switching phenomena reported earlier.« less

  3. [Cleaning implantation burs. Observations using scanning electron microscopy].

    PubMed

    Penel, G; Iost, A; Libersa, J C

    2001-01-01

    Drastic aseptic conditions are necessary in implantological treatments. A good sterilizing procedure of the specific instrumentation, like drills, is based on an efficient cleaning. Because of their design, the cleaning of drills is a real challenge. The aim of this investigation is to evaluate two different cleaning procedures usually used by implantologists. One is based on a manual cleaning, the other on an ultra-sonic cleaning. The instrument observed by scan-electron-microscope, is a I.T.I. system drill. The results show the superiority of the ultra-sonic cleaning. The manual cleaning is especially ineffective on the inside and the cutting part of the drill. Even if ultra-sonic cleaning is definitely a better procedure, it has to be improved. A extensive study should be conducted to optimize the cleaning parameters, if not, single-use drill should be definitely preferred by implantologists.

  4. Sizing of single fluorescently stained DNA fragments by scanning microscopy

    PubMed Central

    Laib, Stephan; Rankl, Michael; Ruckstuhl, Thomas; Seeger, Stefan

    2003-01-01

    We describe an approach to determine DNA fragment sizes based on the fluorescence detection of single adsorbed fragments on specifically coated glass cover slips. The brightness of single fragments stained with the DNA bisintercalation dye TOTO-1 is determined by scanning the surface with a confocal microscope. The brightness of adsorbed fragments is found to be proportional to the fragment length. The method needs only minute amount of DNA, beyond inexpensive and easily available surface coatings, like poly-l-lysine, 3-aminoproyltriethoxysilane and polyornithine, are utilizable. We performed DNA-sizing of fragment lengths between 2 and 14 kb. Further, we resolved the size distribution before and after an enzymatic restriction digest. At this a separation of buffers or enzymes was unnecessary. DNA sizes were determined within an uncertainty of 7–14%. The proposed method is straightforward and can be applied to standardized microtiter plates. PMID:14602931

  5. Nondestructive monitoring damage in composites using scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Wey, A. C.; Kessler, L. W.; Dos Reis, H. L. M.

    1992-01-01

    Several Nicalon fiber reinforced LAS (lithium alumino-silicate) glass matrix composites were tested to study the relation between the residual strength and the different amounts of damage. The samples were fatigued by four-point cyclic loading at a 5 Hz rate at 500 C for a different number of cycles. 10 MHz scanning laser acoustic microscope (SLAM) images were taken to monitor damage on the samples. Our SLAM results indicate that there were defects already existing throughout the sample before fatigue, and the resultant damage pattern from fatigue could be related to the initial defect distribution in the sample. Finally, the fatigued samples were fractured and the residual strength data could not be explained by the cyclic fatigue alone. Rather, the damage patterns evident in the SLAM images were needed to explain the scatter in the data. The results show that SLAM is useful in nondestructively monitoring damage and estimating residual strength of fatigued ceramic composites.

  6. The theory and practice of high resolution scanning electron microscopy

    SciTech Connect

    Joy, D.C. Oak Ridge National Lab., TN )

    1990-01-01

    Recent advances in instrumentation have produced the first commercial examples of what can justifiably be called High Resolution Scanning Electron Microscopes. The key components of such instruments are a cold field emission gun, a small-gap immersion probe-forming lens, and a clean dry-pumped vacuum. The performance of these microscopes is characterized by several major features including a spatial resolution, in secondary electron mode on solid specimens, which can exceed 1nm on a routine basis; an incident probe current density of the order of 10{sup 6} amps/cm{sup 2}; and the ability to maintain these levels of performance over an accelerating voltage range of from 1 to 30keV. This combination of high resolution, high probe current, low contamination and flexible electron-optical conditions provides many new opportunitites for the application of the SEM to materials science, physics, and the life sciences. 27 refs., 14 figs.

  7. 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.

  8. Scanning electron microscopy of human cortical bone failure surfaces.

    PubMed

    Braidotti, P; Branca, F P; Stagni, L

    1997-02-01

    Undecalcified samples extracted from human femoral shafts are fractured by bending and the fracture surfaces are examined with a scanning electron microscope (SEM). The investigation is performed on both dry and wet (hydrated with a saline solution) specimens. SEM micrographs show patterns in many respects similar to those observed in fractography studies of laminated fiber-reinforced synthetic composites. In particular, dry and wet samples behave like brittle and ductile matrix laminates, respectively. An analysis carried out on the basis of the mechanisms that dominate the fracture process of laminates shows that a reasonable cortical bone model is that of a laminated composite material whose matrix is composed of extracellular noncollagenous calcified proteins, and the reinforcement is constituted by the calcified collagen fiber system.

  9. Detector non-uniformity in scanning transmission electron microscopy.

    PubMed

    Findlay, S D; LeBeau, J M

    2013-01-01

    A non-uniform response across scanning transmission electron microscope annular detectors has been found experimentally, but is seldom incorporated into simulations. Through case study simulations, we establish the nature and scale of the discrepancies which may arise from failing to account for detector non-uniformity. If standard detectors are used at long camera lengths such that the detector is within or near to the bright field region, we find errors in contrast of the order of 10%, sufficiently small for qualitative work but non-trivial as experiments become more quantitative. In cases where the detector has been characterized in advance, we discuss the detector response normalization and how it may be incorporated in simulations. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

    SciTech Connect

    Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.; Schemer-Kohrn, Alan L.; Guzman, Anthony D.; Lavender, Curt A.

    2016-03-30

    The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

  11. U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

    SciTech Connect

    Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.; Schemer-Kohrn, Alan L.; Guzman, Anthony D.; Lavender, Curt A.

    2016-10-01

    The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

  12. Comparison of Scheimpflug-photography, specular microscopy and scanning electron microscopy to detect corneal changes in toxicity studies in rats

    SciTech Connect

    Boeker, T.W.; Wegener, A.; Koch, F.; Hockwin, O. )

    1990-01-01

    With an increasing number of in-vivo methods to examine the eyes of laboratory animals, the rat has become an important animal model in experimental eye research. Specular microscopy is a clinical tool to examine the corneal endothelium in-vivo. To evaluate the versatility of this method for small animal eyes, we studied both corneal endothelial cell-count and corneal thickness in normal rats as well as those with diabetic, naphthalene and UV-B cataract. As a reference scanning electron microscopy (SEM) of the corneal endothelium was performed. For cell-counts the correlation coefficient between both methods was found to be sufficient. The comparison of corneal thickness measurement (SEM-values) with specular microscopy and with Scheimpflugbiometry failed to show a satisfactory correlation. The study proves that specular microscopy is a useful tool to document changes also in the endothelium of the rat-cornea.

  13. A two-axis water-immersible MEMS scanning mirror for scanning optical and acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Xu, Song; Huang, Chih-Hsien; Zou, Jun

    2016-03-01

    Fast scanning is highly desired for both ultrasound and photoacoustic microscopic imaging. Limited by water environment required for acoustic propagation, traditional mircoelectromechanical system (MEMS) scanning mirrors could not be widely used. In this paper, a new water-immersible scanning mirror microsystem has been designed, fabricated and tested. Polymer hinges were employed to achieve reliable under water performance. Two pairs of high strength neodymium magnet disc and three compact RF choke inductor were used to actuate mirror module. Experimental results show that the fast axis can reach a mechanical scanning angle of +/-15° at the resonance frequency of 350 Hz in air, and +/-12.5° at the resonance frequency of 240 Hz in water, respectively. The slow axis can reach a mechanical scanning angle of +/-15° at the resonance frequency of 20 Hz in air, and +/-12.5° at the resonance frequency of 13 Hz in water, respectively. The two scanning axes have very different resonance frequencies, which are suitable for raster scanning.

  14. The Integration of Scanning Electron Microscopy, Scanning Probe Microscopy, and Luminescence Spectroscopy in one Platform: New Opportunities and Applications in Photovoltaics

    NASA Astrophysics Data System (ADS)

    Romero, Manuel

    2012-02-01

    We have recently integrated scanning tunneling microscopy (STM), atomic force microscopy (AFM), and near-field scanning optical microscopy (NSOM) onto the mechanical stage of a scanning electron microscope compatible with operation under high vacuum and the use of cryogenics. This instrument is unique in the sense that is not just the assembly of different microscopes but an integrated platform in which both the electron beam and the ultrasharp tip of the AFM/STM/NSOM can be controlled simultaneously and independently as excitation or sensing elements, providing innovative modes of operation and access to optoelectronic properties in the micro and nanoscale not accessible before. Furthermore, this instrument is equipped with focused laser illumination of the tip and detection of luminescence and can be used to measure cathodoluminescence, scanning tunneling luminescence, photoluminescence, and electroluminescence, all with high resolution. In this contribution, we review the application of these techniques to the development of second- and third-generation photovoltaics (PV) beyond those commercially available today. Among these applications, we present the luminescence and electron transport across single grain boundaries in chalcopyrite and kesterite compounds, the detection of single molecule species using plasmonics, the nanoscale imaging of the exciton transport in organic semiconductors, and the insitu manipulation and measurement of nanowires.

  15. Scanning electron microscopy in characterizing seeds of some leguminous trees

    NASA Astrophysics Data System (ADS)

    Ghosh, Nabarun; Chatterjee, Amiyanghshu; Smith, Don W.

    2009-05-01

    SEM has greatly increased our knowledge of the microstructure of seeds. Mature seed coats are rather thick walled and stable in a vacuum: this allows quick preparation for SEM examination, without the need of complicated dehydration techniques. The low level of technical expenditure required, in combination with the high structural diversity exhibited and the intuitive ability to understand the "three dimensional", often aesthetically appealing micro-structures visualized, has turned seed-coat studies into a favorite tool of many taxonomists. We used dry mature seeds of 26 species of 4 Leguminous genera, Acacia, Albizia, Cassia and Dalbergia to standardize a procedure for identifying the seeds through SEM on the seed surface and seed sections. We cut transverse and longitudinal sections of the seeds and observed the sections from different regions of seeds: midseed, near the hilum and two distal ends. Light microscopy showed the color, texture, pleurograms, fissures and hilum at lower magnification. The anatomical study with SEM on the seed sections revealed the size, shape, and number of tiers and cellular organization of the epidermis, hypodermis, endosperm and internal structural details. We found the ornamentation pattern of the seeds including undulations, reticulations and rugae that were species specific. Species of Dalbergia (assamica, latifolia and sissoo), Albizia (odoratissima and procera), Acaia (arabica and catechu) and Cassia (glauca, siamia and spectabilis) are difficult to distinguish externally, but SEM studies provided enough characteristic features to distinguish from the other. This technique could be valuable in identifying seeds of important plant species for conservation and trading.

  16. Analysis of somitogenesis using multiphoton laser scanning microscopy (MPLSM)

    NASA Astrophysics Data System (ADS)

    Dickinson, Mary E.; Longmuir, Kenneth J.; Fraser, Scott E.

    2001-04-01

    In order to study complex cellular interactions in the developing somite and nervous system, we have been refining techniques for labeling and imaging individual cells within the living vertebrate embryo. Most recently, we have been using MPLSM to analyze cellular behaviors, such as cell migration, filopodial extension, cell process collapse, and neuron pathfinding using time-lapse microscopy in 3-dimensions (3-d). To enhance the efficiency of two-photon excitation in these samples, we have been using a Zeiss LSM 510 NLO fiber delivery system with a Grating Dispersion Compensator (GDC). This system not only offers the convenience of fiber delivery for coupling our Ti:Sapphire laser to the microscope, but also affords us precise control over the pulsewidth of the mode- locked beam. In addition, we have developed a novel peptide/non-cationic lipid gene delivery system to introduce GFP plasmid into somite cells. This approach has allowed us to generate detailed 3-d images of somite cell morphologies at various stages of somite development in a way that best preserves the vitality of the cells being imaged.

  17. 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.

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

    PubMed

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

    2014-03-01

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

  19. An optical scan-calibration system in scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Yunliang; Zhang, Hao; Wang, Keyi

    2009-11-01

    Scanning Probe Microscopes(SPM) use piezoelectric actuators to generate the scans. But the nonlinearities inherent in the piezoelectric actuators limit the usefulness of the instruments in precision metrology. This paper describes a simple optical beam displacement sensor that is used to accurately measure the (x,y) position of a piezoelectric tube scanner used in Scanning Near-field Optical Microscope(SNOM). As the nonlinearities is too complex to make up a simple math model, this paper use the Artificial neural network to Calibrate the nonlinearities.

  20. Combined optical and mechanical scanning in optical-resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Li, Lei; Yeh, Chenghung; Hu, Song; Wang, Lidai; Soetikno, Brian T.; Chen, Ruimin; Zhou, Qifa; Shung, K. Kirk; Maslov, Konstantin I.; Wang, Lihong V.

    2014-03-01

    Combined optical and mechanical scanning (COMS) in optical-resolution photoacoustic microscopy (OR-PAM) has provided five scanning modes with fast imaging speed and wide field of view (FOV). With two-dimensional (2D) galvanometer-based optical scanning, we have achieved a 2 KHz B-scan rate and 50 Hz volumetric-scan rate, which enables real-time tracking of cell activities in vivo. With optical-mechanical hybrid 2D scanning, we are able to image a wide FOV (10×8 mm2) within 150 seconds, which is 20 times faster than the conventional mechanical scan in our second-generation OR-PAM. With three-dimensional mechanical-based contour scanning, we can maintain the optimal signal-to-noise ratio and spatial resolution of OR-PAM while imaging objects with uneven surfaces, which is ideal for fast and quantitative studies of tumors and the brain.