Controlling the formation process and atomic structures of single pyrazine molecular junction by tuning the strength of the metal–molecule interaction

2017 ◽  
Vol 19 (15) ◽  
pp. 9843-9848 ◽  
Author(s):  
Satoshi Kaneko ◽  
Ryoji Takahashi ◽  
Shintaro Fujii ◽  
Tomoaki Nishino ◽  
Manabu Kiguchi
Keyword(s):  
Formation Process ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Molecular Junction ◽  
Break Junction ◽  
Atomic Structures ◽  
Molecule Interaction

Fabrication of single pyrazine molecular junction with Au, Ag and Cu electrodes using mechanically controllable break junction technique in ultra-high vacuum.

Ultra High Vacuum Scanning Tunneling Microscopy Observation of Multilayer Step Structure on GaAs and AlAs Vicinal Surface Grown by Metalorganic Vapor Phase Epitaxy

1996 ◽  
Vol 448 ◽  
Author(s):  
Jun-Ya Ishizaki ◽  
Yasuhiko Ishizaki ◽  
Takashi Fukui
Keyword(s):  
Scanning Tunneling Microscopy ◽  
High Vacuum ◽  
Gaas Layer ◽  
Layer Growth ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Vicinal Surface ◽  
Microscopy Observation ◽  
Tunneling Microscopy ◽  
Atomic Structures

AbstractWe observe the atomic structures at the multilayer step region on MOVPE-grown GaAs (001) vicinal surface using ultra high vacuum scanning tunneling microscopy (UHV-STM), and clarify that (4×2) or (4×3) like reconstruction units are dominant. Oxide free AlAs surfaces grown on GaAs vicinal surface are also successfully observed by UHV-STM. The reconstruction units at the multilayer step region on AlAs surface have the same units on GaAs vicinal surface. GaAs surface has the lack of dimmer rows on the terrace region just below the multilayer step region, while AlAs surface has dimmer rows even on the terrace just below the multilayer step region. GaAs layer growth leads tothe step bunching phenomenon and AlAs surface leads to the step debunching phenomenon.

Hrem Investigation of the Structure of the Σ5(210)/[001] Symmetric Tilt Grain Boundaries in Nb.

1991 ◽  
Vol 229 ◽  
Author(s):  
G. H. Campbell ◽  
S. M. Foiles ◽  
Wayne E. King ◽  
M. Rühle ◽  
W. Wien
Keyword(s):  
High Vacuum ◽  
High Resolution Electron Microscopy ◽  
Ultra High Vacuum ◽  
Experimental Result ◽  
Energy Structure ◽  
Interatomic Potentials ◽  
Pseudopotential Theory ◽  
Atomic Structures ◽  
Embedded Atom ◽  
Symmetric Tilt

AbstractWe have simulated the atomic structures of the Σ 5 (210)/[001 ] symmetric tilt grain boundary using interatomic potentials for Nb developed employing the embedded atom method (EAM) and the model generalized pseudopotential theory (MGPT). These potentials do not predict the same lowest energy structure for the Σ 5 (210)/[001]. Using the ultra high vacuum diffusion bonding process, we have fabricated Σ 5 (210)/[001] bicrystals. The samples have been observed using high resolution electron microscopy and the observed images have been compared with those simulated based on the structures predicted theoretically. The experimental result for the Σ 5 (210)/[001] is in close agreement with the structure predicted using the EAM.

Tribochemical Study of Hydrogenated Carbon Coatings With Different Hydrogen Content Levels in Ultra High Vacuum

1997 ◽  
Vol 119 (3) ◽  
pp. 437-442 ◽  
Author(s):  
Xiaohan Yun ◽  
David B. Bogy ◽  
C. Singh Bhatia
Keyword(s):  
Hydrogen Content ◽  
High Vacuum ◽  
Carbon Films ◽  
Ultra High Vacuum ◽  
Carbon Overcoat ◽  
Carbon Coatings ◽  
Disk Interface ◽  
Atomic Structures ◽  
Chemical Factors ◽  
Friction Measurements

Hydrogenated carbon films (CHx) with different hydrogen content percentages have been examined. Drag tests on CHx coated disks, using 50 percent Al2O3/TiC sliders, with and without carbon coating on the slider air bearing surfaces (ABS), were conducted in an ultra high vacuum chamber equipped with a mass spectrometer. Mass fragments of lubricant released from the head disk interfaces were recorded in real time along with friction measurements. The results show that a higher hydrogen content in the carbon overcoat can improve wear durability by reducing the friction coefficient and affecting the chemical reactions between the sliders and the lubricant. A carbon overcoat on the slider ABS can protect Z-dol lubricant from catalytic reaction with the Al2O3 in the slider material. The wear durability at the head disk interface is controlled by combined mechanical and chemical factors, which are defined by the atomic structures of the contacting surfaces.

UHV-TED study of clean Si(100) surface structures

1993 ◽  
Vol 51 ◽  
pp. 1002-1003
Author(s):  
Ganesh Jayaram
Keyword(s):  
Surface Science ◽  
High Vacuum ◽  
Careful Analysis ◽  
Ultra High Vacuum ◽  
Electron Gun ◽  
Silicon Surfaces ◽  
Diffraction Spot ◽  
Stable Operation ◽  
Thin Sample ◽  
Atomic Structures

Detailed information about the structure of silicon surfaces is very important prior to deposition of metal contacts. Though transmission electron diffraction is sensitive to the atomic structures of both the surface and the bulk, under appropriate conditions, information on the structure of the surface can be obtained from a careful analysis of the diffraction spot intensities.Since Si(100) surface is highly reactive (sticking coefficient for water = 1), preparation and observation of clean surfaces necessitates ultra-high vacuum (UHV) conditions. A thin sample of Si(100) (B doped to 1 ohm-cm) was prepared for observation inside a Hitachi UHV-H9000 300keV electron microscope (stable operation pressure ∼9xl0-11 Torr). It was mechanically polished, dimpled and ion-milled before being transferred into a UHV surface science chamber attached to the microscope. In situ sample preparation carried out inside this chamber involved a combination of sputtering using 2-4 keV argon ions (to clean the surface) and electron-gun annealing cycles (to order the surface).

High-Resolution Lattice Images of Superconductors Observed at 4.2 K

1990 ◽  
Vol 48 (1) ◽  
pp. 16-17
Author(s):  
Hiroyuki Yoshida ◽  
Yasuhiro Yokota ◽  
Hatsujiro Hashimoto ◽  
Masashi Iwatsuki ◽  
Yoshiyasu Harada
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Oxide Superconductors ◽  
Atomic Structures ◽  
Cryo Electron Microscopy ◽  
Resolution Observation ◽  
Lattice Images ◽  
High Resolution Images

High resolution cryo electron microscopy has been applied to the observation of microstructures of A15-type and oxide superconductors. In order to study the relation between atomic structures and superconducting properties the atomic resolution observation at cryogenic temperatures seems to be important, especially for high Tc superconductors with perovskite structure whose coherent length along c axis is closed to the lattice spacings. High resolution lattice images were obtained using a superconducting cryo electron microscope JEM-2000 SCM operated at 160 KV. The microscope enable the specimen to keep at 4.2 K without thermal drift and vibration under ultra high vacuum. The magnetic field at the specimen position is 1.4 T when the electron microscope is operated at 160 kV.Figure 1 shows a high resolution image of the electropolished thin crystal of Nb3(A10.77Ge0.23) (Tc=19 K). In the both sides of the grain boundary the (100) lattice fringes with 0.52 nm spacing of the A15 structure are clearly resolved. The high resolution images obtained for Nb3Sn superconductors gave the bright dots at the position of Nb atom chains along 001 direction as confirmed by the image contrast calculation.

Intensity measurement of surface diffraction spots by EELS

1992 ◽  
Vol 50 (1) ◽  
pp. 282-283
Author(s):  
P. Xu ◽  
L. D. Marks
Keyword(s):  
High Vacuum ◽  
Absolute Intensity ◽  
Intensity Measurement ◽  
Ultra High Vacuum ◽  
Plan View ◽  
Atomic Structures ◽  
Transmission Electron ◽  
Clean Environment ◽  
Electron Microscopes ◽  
Surface Diffraction

With the development of the modern ultra-high vacuum (UHV) transmission electron microscopes, it has become possible to study the surfaces of various materials in a clean environment. Transmission electron diffraction in a plan view geometry is particularly powerful in solving the surface atomic structures, for example Si(111)-7x7. Surface diffraction spots in such a pattern are usually quite strong, readily apparent on a phosphor screen. In addition, these spots are much clearer in an off zone diffraction pattern. This paper presents the absolute intensity measurement of the surface spots intensity using an electron energy loss spectrometer.

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

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