Hrem Study of Ultra Thin Titanium Films

1997 ◽  
Vol 472 ◽  
Author(s):  
T. Braisaz ◽  
P. Ruterana ◽  
G. Nouet ◽  
Ph. Komninou ◽  
Th. Kehagias ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Vacuum ◽  
High Resolution Electron Microscopy ◽  
Zone Axis ◽  
Ultra High Vacuum ◽  
Electron Gun ◽  
Mirror Plane ◽  
Planar Defects ◽  
Resolution Electron ◽  
Order Of Magnitude

ABSTRACTHigh resolution electron microscopy has been used to characterize the structure of ultra thin films of titanium deposited on KBr substrate by Ultra High Vacuum (UHV) electron-gun evaporation. The size of the grains has an order of magnitude of 10 nm whatever the substrate temperature. The observations have been carried out along <1123> zone axis. Some of the grains contain planar defects which were identified as the twin {1011}. The atomic structure of this twin is characterized by a mirror plane similar to that observed in polycrystalline titanium. Additionaly, this structure can be modified by a b2/2 twinning dislocation.

Atomic-level imaging of the surface structure of Ag2O

1984 ◽  
Vol 42 ◽  
pp. 656-657
Author(s):  
William Krakow
Keyword(s):  
High Vacuum ◽  
Atomic Level ◽  
Ultra High Vacuum ◽  
Research Groups ◽  
Resolution Electron ◽  
Surface Reconstructions ◽  
Order Of Magnitude ◽  
High Resolution Electron Microscope ◽  
Saturated Structure ◽  
Transmission And Reflection

In recent years electron microscopy has been used to image surfaces in both the transmission and reflection modes by many research groups. Some of this work has been performed under ultra high vacuum conditions (UHV) and apparent surface reconstructions observed. The level of resolution generally has been at least an order of magnitude worse than is necessary to visualize atoms directly and therefore the detailed atomic rearrangements of the surface are not known. The present author has achieved atomic level resolution under normal vacuum conditions of various Au surfaces. Unfortunately these samples were exposed to atmosphere and could not be cleaned in a standard high resolution electron microscope. The result obtained surfaces which were impurity stabilized and reveal the bulk lattice (1x1) type surface structures also encountered by other surface physics techniques under impure or overlayer contaminant conditions. It was therefore decided to study a system where exposure to air was unimportant by using a oxygen saturated structure, Ag2O, and seeking to find surface reconstructions, which will now be described.

Is there an electron wind?

1990 ◽  
Vol 48 (4) ◽  
pp. 798-799
Author(s):  
L. D. Marks ◽  
J. P. Zhang
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Zone Axis ◽  
Electron Holography ◽  
Electron Wave ◽  
Small Particles ◽  
Resolution Electron ◽  
Pass Through ◽  
Electron Wind ◽  
Inelastic Scatter

A not uncommon question in electron microscopy is what happens to the momentum transferred by the electron beam to a crystal. If the beam passes through a crystal and is preferentially diffracted in one direction, is the momentum ’lost’ by the beam transferred to the crystal? Newton’s third law implies that this must be the case. Some experimental observations also indicate that this is the case; for instance, with small particles if the particles are supported on the top surface of a film they often do not line up on the zone axis, but if they are on the bottom they do. However, if momentum is transferred to the crystal, then surely we are dealing with inelastic scattering, not elastic scattering and is not the scattering probability different? In addition, normally we consider inelastic scatter as incoherent, and therefore the part of the electron wave that is inelastically scattered will not coherently interfere with the part of the wave that is scattered; but, electron holography and high resolution electron microscopy work so the wave passing through a specimen must be coherent with the wave that does not pass through the specimen.

A Field Emission Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 6-7
Author(s):  
A. Tonomura ◽  
T. Komoda
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
High Vacuum ◽  
High Resolution Electron Microscopy ◽  
Ultra High Vacuum ◽  
Electron Optics ◽  
Ion Pumps ◽  
High Brightness ◽  
Emission Electron ◽  
Resolution Electron

We have developed a field emission electron microscope. Although field emission gun requires ultra high vacuum and skillful technique, it brings about the favorable characteristics of high brightness and small energy spread. This characteristics will enable a significant progress in coherent electron optics and high resolution electron microscopy, especially in electron beam holography.Its column is Hitachi HU-11C Electron Microscope modified for ultra high vacuum operation, and it is evacuated with five ion pumps. Field emission gun is divided into two parts and is evacuated differentially with two ion pumps and a sublimation pump. The final pressures in these rooms are 5x10-10 Torr and 5x10-8 Torr respectively.

Surface studies in UHV: Applications of High-resolution electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 444-445
Author(s):  
M. R. McCartney ◽  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Vacuum ◽  
High Resolution Electron Microscopy ◽  
Plan View ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Video Systems ◽  
Electron Microscopes

The examination of surfaces requires not only that they be free of adsorbed layers but the environment of the sample must also be maintained at high vacuum so that the surfaces remain clean. The possibility of resolving surface structures with atomic resolution has provided the motivation for optimizing intermediate and high voltage electron microscopes for this particular application. Electron microscopy offers a variety of techniques which have the capability of achieving atomic level detail of surfaces including plan-view imaging, REM and profile imaging. Operation at higher voltages permits reasonable pole piece dimensions thereby providing space for in situ studies yet still compatible with high resolution. Moreover, video systems can be attached which permit observation and recording of dynamic phenomena without compromising microscope performance.

Crystal defects of mordenite structures

1999 ◽  
Vol 14 (6) ◽  
pp. 2616-2620 ◽  
Author(s):  
S. G. Song
Keyword(s):  
Electron Microscopy ◽  
Chemical Properties ◽  
High Resolution Electron Microscopy ◽  
Crystal Defects ◽  
Channel Structure ◽  
Planar Defects ◽  
Resolution Electron ◽  
Main Emphasis ◽  
Pore Blockage ◽  
Catalytic Applications

Crystal defects in mordenite materials were observed and characterized by high-resolution electron microscopy (HREM). These defects are identified as line, planar, and 3D defects, which may result in pore blockage of the mordenite channel structure and be detrimental to their chemical properties for catalytic applications. The planar defects are the most severe ones affecting the structural properties of mordenite because of their density and scale. The main emphasis of this investigation is focused on the crystallographic aspects of these defects.

Recent trends in high-resolution electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 530-533
Author(s):  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Two Dimensional ◽  
Planar Defects ◽  
Medium Voltage ◽  
Resolution Electron ◽  
Routine Basis ◽  
Recent Trends ◽  
Electron Microscopes

The recent advent of high-resolution electron microscopes (HREMs) capable of resolving sub-2-Ångstrom detail on a routine basis has led to an enormous increase in the range of materials which can be usefully studied. Not only is it possible to resolve individual atomic columns in low index zones of most common metals but observations of semiconductors, for example, are no longer restricted to the traditional [110] zone, thereby making it feasible at last to obtain two-dimensional information about surfaces, interfaces and other planar defects. There is a worldwide upsurge of interest in the capabilities of these machines and the so-called medium-voltage (300-400kV) HREMs are selling rapidly despite their considerable expense. Our objective here is to provide a brief and selective overview of the latest applications and likely trends in HREM studies of materials - further details can be found elsewhere in these proceedings. No attempt is made to review instrumentation developments since they are being considered separately.

A New Method of Preparing Tilt Boundaries for High Resolution Electron Microscopy

1987 ◽  
Vol 115 ◽  
Author(s):  
William Krakow ◽  
Victor Castańo
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
High Resolution ◽  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Zone Axis ◽  
New Method ◽  
Lateral Overgrowth ◽  
Resolution Electron ◽  
Tilt Boundaries

ABSTRACTA new method of preparing bicrystal substrates of NaCl with a common tilt zone axis has been developed. Upon a lateral overgrowth of NaCl, bridging the two mechanically polished and oriented crystals, very thin films can then be vapor deposited. Au bicrystals of ∼ 75Å thickness and b.c.c. Cr films of similar thickness with grain boundaries have been fabricated.

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