A metal- coating Chamber for High-Resolution Cryo-SEM

1990 ◽  
Vol 48 (1) ◽  
pp. 418-419
Author(s):  
John G. Sheehan
Keyword(s):  
High Resolution ◽  
Colloidal Suspensions ◽  
Metal Coating ◽  
Colloidal Interactions ◽  
Amorphous Ice ◽  
High Vapor ◽  
Particulate Coatings ◽  
20 Nm ◽  
Film Nucleation ◽  
Coating Chamber

Improvements in particulate coatings for printable paper require understanding mechanisms of colloidal interactions in paper coating suspensions. One way to deduce colloidal interactions is to mage particle spacings and orientations at high resolution with cryo-SEM. Recent improvements in cryo-SEM technique have increased resolution enough to image particles in coating paints,vhich are sometimes smaller than 100 nm. In this report, a metal-coating chamber is described for preparation of colloidal suspensions for cryo-SEM at resolution down to 20 nm. It was found that etching is not necessary to achieve this resolution.A 120 K cryo-SEM sample will remain in an SEM for hours without noticeable condensation of imorphous ice. This is due to the high vapor pressure of vapor-condensed amorphous ice, measured by Kouchi. However, clean vacuum is required to coat samples with the thinnest possible continuous metal films which are required for high magnification SEM. Vapor contaminants, especially hrydrocarbons, are known to interfere with thin-film nucleation and growth so that more metal is needed to form continuous films, and resolution is decreased. That is why the metal-coating chamber in fig. 1 is designed for the cleanest possible vacuum. Feedthroughs for the manipulator md the shutter, which are operated during metal coating, are sealed with leak-proof stainless-steel Dellows. The transfer rod slides through a baseplate feedthrough that is double o-ring sealed.

Ultra high resolution SEM at high voltage images individual fab fragments applied as molecular label to cell surface receptors

1989 ◽  
Vol 47 ◽  
pp. 70-71
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Resolution ◽  
High Energy ◽  
Metal Coating ◽  
Beam Diameter ◽  
Surface Receptors ◽  
Surface Mobility ◽  
Metal Atoms ◽  
Shadowing Effect ◽  
Imaging Mode ◽  
Deposition Techniques

Topographic ultra high resolution can now routinely be established on bulk samples in cold field emission scanning electron microscopy with a second generation of microscopes (FSEM) designed to provide 0.5 nm probe diameters. If such small probes are used for high magnification imaging, topographic contrast is so high that remarkably fine details can be imaged on 2DMSO/osmium-impregnated specimens at ribosome surfaces even without a metal coating. On TCH/osmium-impregnated specimens topographic resolution can be increased further if the SE-I imaging mode is applied. This requires that beam diameter and metal coating thickness be made smaller than the SE range of ~1 nm and background signal contributions be reduced. Subnanometer small probes can be obtained (only) at high accelerating voltages. Subnanometer thin continuous metal films can be produced under the following conditions: self-shadowing effect between metal atoms must be reduced through appropriate deposition techniques and surface mobility of metal atoms must be diminished through high energy sputtering and/or specimen cooling.

High-resolution scanning electron microscopy in biology

1990 ◽  
Vol 48 (3) ◽  
pp. 14-15
Author(s):  
Keiichi Tanaka
Keyword(s):  
High Resolution ◽  
Immunoglobulin M ◽  
Metal Coating ◽  
Biological Macromolecules ◽  
Ultrahigh Resolution ◽  
Preparation Methods ◽  
Low Contrast ◽  
Almost All ◽  
Charging Effect ◽  
Scanning Electron

With the development of scanning electron microscope (SEM) with ultrahigh resolution, SEM became to play an important role in not only cytology but also molecular biology. However, the preparation methods observing tiny specimens with such high resolution SEM are not yet established.Although SEM specimens are usually coated with metals for getting electrical conductivity, it is desirable to avoid the metal coating for high resolution SEM, because the coating seriously affects resolution at this level, unless special coating techniques are used. For avoiding charging effect without metal coating, we previously reported a method in which polished carbon plates were used as substrate. In the case almost all incident electrons penetrate through the specimens and do not accumulate in them, when the specimens are smaller than 10nm. By this technique some biological macromolecules including ribosomes, ferritin, immunoglobulin G were clearly observed.Unfortunately some other molecules such as apoferritin, thyroglobulin and immunoglobulin M were difficult to be observed only by the method, because they had very low contrast and were easily damaged by electron beam.

Influence of Interfacial Copper on the Ti-SiO2 Reaction During Nitridation of Cu-Ti Films

1995 ◽  
Vol 398 ◽  
Author(s):  
Daniel Adams ◽  
T.L. Alford ◽  
N.D. Theodore ◽  
T. Laursen ◽  
S.W. Russell ◽  
...  
Keyword(s):  
Free Surface ◽  
High Resolution ◽  
Consumption Rate ◽  
Catalytic Effect ◽  
Energy Dispersive ◽  
Ti Alloy ◽  
Alloy Films ◽  
X Ray ◽  
20 Nm ◽  
Ti Films

ABSTRACTCu(90 nm)/Ti(20 nm) bilayers and Cu(Ti 27 at.%) alloy films were deposited on SiO2 and annealed in an NH3 ambient at temperatures 400–700° C for 30 min. During annealing Ti segregated to both the free surface and the alloy/SiO2 interface. At the surface Ti reacted with NH3 to form TiN, whereas at the interface the Ti reacted with the SiO2 to form a TiO/Ti5Si3 structure. High resolution energy dispersive x-ray analysis revealed the presence of interfacial Cu between the Ti-silicide and Ti-oxide layers at temperatures greater than 450°C. Using Cu-Ti alloy films enhanced the Si02 consumption rate by a factor of 3-4 compared to that of pure Ti. It is suggested that the interfacial Cu is responsible for the increased rate. It is plausible that an interfacial Cu2O component has a catalytic effect on the Ti- SiO2 reaction.

Spot Electron-Beam Lithography as a Novel Method of High Resolution Pattern Nanofabrication

2014 ◽  
Vol 215 ◽  
pp. 459-461
Author(s):  
Alexander S. Samardak ◽  
Margarita V. Anisimova ◽  
Alexey V. Ognev ◽  
Vadim Yu. Samardak ◽  
Liudmila A. Chebotkevich
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Electron Beam Lithography ◽  
The Novel ◽  
Practical Applications ◽  
Novel Method ◽  
20 Nm ◽  
Scanning Electron

We present a novel method of pattern nanofabrication with high resolution and small shape defects using the traditional electron-beam lithography (EBL) or only a scanning electron microscope (SEM). Our method of Spot EBL is extremely fast, highly scalable on big areas, capable of sub-20 nm resolution and fabrication of polymer patterns with complicated shapes. We show the nanostructure images fabricated by Spot EBL and propose practical applications of the novel method.

Image analysis of 2-D Na,K-ATPase crystals maintained in vitreous ice

1988 ◽  
Vol 46 ◽  
pp. 396-397
Author(s):  
Manoj Misra ◽  
Harry C. Beall ◽  
Kenneth A. Taylor ◽  
H.P. Ting-Beall
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Electron Microscope ◽  
High Resolution ◽  
Optical Diffraction ◽  
Native State ◽  
Amorphous Ice ◽  
Ordered Arrays ◽  
Minimal Dose ◽  
Molecular Description

The molecular description of the Na,K-ATPase in the native state at high-resolution is required for the detailed description of the mechanism by which the active transport of Na and K ions occurs. Our efforts, therefore, are directed toward obtaining this molecular description by means of electron microscopy of ordered arrays of Na,K-ATPase molecules preserved in the frozen-hydrated state in amorphous ice.The procedure for crystallization of Na,K-ATPase was similar to that of Mohraz et al. Electron microscope grids for cryo-microscopy were prepared essentially as described by Dubochet et al. Frozen-hydrated specimens were examined in the Philips 420 electron microscope using a Gatan model 626 Cryotransfer system and cooling holder. Micrographs were recorded at 36000X under minimal dose conditions. Electron micrographs of frozen-hydrated membranes were screened initially by optical diffraction and examined for the presence of 4-6 rows of crystal lattice without any discernible visual disorder.

High-resolution biological microanalysis in the field-emission STEM

1990 ◽  
Vol 48 (2) ◽  
pp. 154-155
Author(s):  
R.D. Leapman ◽  
S.B. Andrews
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Dose ◽  
Dark Field ◽  
X Ray ◽  
Macromolecular Assemblies ◽  
Freeze Dried ◽  
Annular Dark Field ◽  
20 Nm ◽  
Electron Energy Loss

The recent availability of a cryotransfer stage, efficient electron energy loss spectrometers (EELS), and ultrathin window energy-dispersive x-ray spectrometers (EDXS) for the VG Microscopes HB501 field-emission STEM now provides this instrument with the potential for high resolution (<20 nm) biological microanalysis. In practice, limits are normally imposed by the sample itself, due to damage in the electron beam and to changes in structure and composition during freezing, sectioning, transfering and freeze-drying. We have therefore investigated what types of useful high-resolution analytical information can be obtained from rapidly frozen samples, including thin tissue cryosections and frozen isolated macromolecules and macromolecular assemblies.Frozen-hydrated samples were cryotransfered at ~-175C into the VG STEM after which a vacuum of ~3x10-9 mbar was maintained. Samples were freeze-dried by warming to ~-90C over 30 min and were then recooled to below ~-160C to minimize radiation damage and contamination during analysis. Digital annular dark-field images were obtained at low dose (~10 e/Å2) with single electron sensitivity, using a probe current of 2 to10 pA and a beam energy of 100 keV.

Uranium Fixation During Uranium Migration Under an Oxidizing Condition

1994 ◽  
Vol 353 ◽  
Author(s):  
Takashi Murakami ◽  
Katsuyuki Tsuzuki ◽  
Tsutomu Sato ◽  
Hiroshi Isobe ◽  
Toshihiko Ohnuki
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Rock Specimen ◽  
Uranium Mineral ◽  
Ore Deposit ◽  
Iron Minerals ◽  
Transmission Electron ◽  
Uranium Migration ◽  
20 Nm

AbstractA rock specimen, collected downstream of the Koongarra uranium ore deposit, Australia, was examined mainly by high resolution transmission electron microscopy in order to understand the uranium fixation mechanism. Uranium was found to exist as saleeite (Mg(UO2)2(PO4)2.10H2O) microcrystals of 1 – 20 nm scattered between iron minerals (mainly goethite and hematite) of 2 – 50 nm. The microtextural relationship between saléeite and the iron minerals revealed that the iron minerals function as catalyst for the formation of saléeite. The intermediate metamict microstructures of the saléeite microcrystals are consistent with the estimated formation age of saléeite, 1 to 3 × 106 years. Uranium has been, thus, fixed as saléeite downstream as well as in the secondary ore deposit. Saléeite in the secondary ore deposit showed completely periodic to fully metamict microstructures, suggesting that saléeite, a major uranium mineral in the secondary ore deposit, probably began to form a few million years ago and continued to form for the next million years.

In Situ High-Resolution Observation for Decomposition of NaAlH4

2007 ◽  
Vol 561-565 ◽  
pp. 1621-1624
Author(s):  
Hiroshi Kawasaki ◽  
Somei Ohnuki ◽  
Takanori Suda ◽  
Naoyuki Hashimoto ◽  
Yoshitsugu Kojima
Keyword(s):  
High Resolution ◽  
Critical Issue ◽  
Reactive Intermediate ◽  
Hydrogen Storage Materials ◽  
Hydrogen Capacity ◽  
Resolution Observation ◽  
Structural Details ◽  
20 Nm ◽  
High Resolution Observation

NaAlH4 has a theoretical hydrogen capacity of 5.6 wt. % with two-step reaction, and the control of the reaction temperature and reversibility is a critical issue for onboard application. To clarify nano-structural details of decomposition of NaAlH4, the in-situ annealing experiment was carried out in a high resolution microscope. It was confirmed that NaAlH4 decomposed at between 200 and 300°C, resulted in formation of many gas bubbles at interface between the particle and oxide film. A reactive intermediate, Na3AlH6, may decompose in this temperature range. Sodium alanate particle was originally agglomeration of small nano-sized crystal with the size of 10 – 20 nm, and the crystal grain grew to 110 nm in diameter after completing decomposition at around 400°C. This is the first step for examination of the microstructural response of catalysts on hydrogen storage materials.

scholarly journals High-Resolution Imaging of Dried and Living Single Bacterial Cell Surfaces: Artifact or Not?

2011 ◽  
Vol 19 (5) ◽  
pp. 22-25 ◽  
Author(s):  
Dominik Greif ◽  
Daniel Wesner ◽  
Dario Anselmetti ◽  
Jan Regtmeier
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Metal Coating ◽  
Environmental Scanning ◽  
Cell Surfaces ◽  
Critical Point Drying ◽  
Resolution Imaging ◽  
Sem Imaging ◽  
Scanning Electron

When studying highly resolved scanning electron microscope images of cell surfaces, the question arises, whether the observed patterns are real or just artifacts of the cell preparation process. The following steps are usually necessary for preparation: fixation, drying, and metal coating. Each step might introduce different artifacts. Clever techniques have been developed to dry cells as gently as possible, for example critical point drying with different organic solvents and CO2. Instrument manufacturers also have taken account of this issue, for example, through the realization of the environmental scanning electron microscope (ESEM), operating with a low-vacuum environment saturated with water so that samples might stay hydrated. Another approach is the extreme high-resolution scanning electron microscope (XHR SEM), where the electron beam is decelerated shortly before reaching the sample. This technique requires no metal coating of the sample. Cryo-SEM also may be used, where no sample preparation is required beyond freezing in a high-pressure freezer or other cryo-fixation device. Then the cell can be examined in the frozen, hydrated state using a cryostage. However, at least some kind of preparation is necessary for SEM imaging, and we wanted to find out what changes the preparation makes on the cell surface.

Microstructural Characterization Methods for Magnetic Thin Films

1999 ◽  
Vol 562 ◽  
Author(s):  
J. E. Wittig ◽  
J. Bentley ◽  
T. P. Nolan
Keyword(s):  
Thin Films ◽  
High Resolution ◽  
Microstructural Characterization ◽  
Magnetic Thin Films ◽  
Complete Analysis ◽  
Structure Property ◽  
Characterization Methods ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
20 Nm

ABSTRACTMicrostructural characterization is key to determining the structure-property-processing relationships required to optimize the performance of magnetic thin films for longitudinal magnetic recording. Since the grain size of modem recording media is on the order of 10 to 20 nm, only high-resolution characterization methods such as transmission electron microscopy (TEM) can accurately describe the microstructure. Complete analysis requires a combination of conventional and high-resolution TEM imaging with analytical methods such as energy dispersivespectroscopy and energy-filtered TEM imaging. This paper provides examples from CoCr(Pt,Ta) alloys that reveal the strengths and limitations of these characterization methods as they apply to microstructural characterization of magnetic thin films.

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