An Illuminating System of a 100-kV Analytical Electron Microscope with a Field-Emission Electron Gun

1990 ◽  
Vol 48 (1) ◽  
pp. 122-123
Author(s):  
A. Delong ◽  
J. Chmelík ◽  
V. Kolařík
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Analytical Electron Microscopy ◽  
Electron Gun ◽  
Transmission Mode ◽  
Resolving Power ◽  
Objective Lens ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Illuminating System

Our aim was to design a microscope for application in both the classical transmission electron microscopy (CTEM) and in the analytical electron microscopy having in the scanning modes (SEM, STEM) a resolving power approaching that in the CTEM. The problem can be optimally solved by using the field emission source of electrons. The illuminating system and the objective lens have the following parameters:a) The resolving power of the objective lens in the transmission mode is as high as 3.5 Å.b) The optical aberrations of the pre—field of the objective lens and of the set of condenser lenses allow a resolution of approx. 5 Å to be achieved in the scanning mode.c) The illuminated area of the specimen observed in the transmission mode is large enough to allow operation with the objective lens switched on at a magnification 1000 x.

The effect of small additions of Cu on precipitation in Al-Mg-Si alloys

1990 ◽  
Vol 48 (2) ◽  
pp. 442-443
Author(s):  
M. Tamizifar ◽  
G. Cliff ◽  
R.W. Devenish ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Argon Atmosphere ◽  
Age Hardening ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Analytical Electron ◽  
Scanning Transmission

Small additions of copper, <1 wt%, have a pronounced effect on the ageing response of Al-Mg-Si alloys. The object of the present investigation was to study the effect of additions of copper up to 0.5 wt% on the ageing response of a series of Al-Mg-Si alloys and to use high resolution analytical electron microscopy to determine the composition of the age hardening precipitates.The composition of the alloys investigated is given in Table 1. The alloys were heat treated in an argon atmosphere for 30m, water quenched and immediately aged either at 180°C for 15 h or given a duplex treatment of 180°C for 15 h followed by 350°C for 2 h2. The double-ageing treatment was similar to that carried out by Dumolt et al. Analyses of the precipitation were carried out with a HB 501 Scanning Transmission Electron Microscope. X-ray peak integrals were converted into weight fractions using the ratio technique of Cliff and Lorimer.

scholarly journals Analytical High-resolution Electron Microscopy Reveals Organ-specific Nanoceria Bioprocessing

2017 ◽  
Vol 46 (1) ◽  
pp. 47-61 ◽  
Author(s):  
Uschi M. Graham ◽  
Robert A. Yokel ◽  
Alan K. Dozier ◽  
Lawrence Drummy ◽  
Krishnamurthy Mahalingam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Organ Specific

This is the first utilization of advanced analytical electron microscopy methods, including high-resolution transmission electron microscopy, high-angle annular dark field scanning transmission electron microscopy, electron energy loss spectroscopy, and energy-dispersive X-ray spectroscopy mapping to characterize the organ-specific bioprocessing of a relatively inert nanomaterial (nanoceria). Liver and spleen samples from rats given a single intravenous infusion of nanoceria were obtained after prolonged (90 days) in vivo exposure. These advanced analytical electron microscopy methods were applied to elucidate the organ-specific cellular and subcellular fate of nanoceria after its uptake. Nanoceria is bioprocessed differently in the spleen than in the liver.

Mixed-layer mica-chlorite in very low-grade metaclastites from the Malàguide Complex (Betic Cordilleras, Spain)

Clay Minerals ◽  
2001 ◽  
Vol 36 (3) ◽  
pp. 307-324 ◽  
Author(s):  
M. D. Ruiz Cruz
Keyword(s):  
Electron Microscopy ◽  
Mixed Layer ◽  
Analytical Electron Microscopy ◽  
Low Grade ◽  
X Ray ◽  
Betic Cordilleras ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Microscopy Data ◽  
Ray Patterns

AbstractMixed-layered phyllosilicates with composition intermediate between mica and chlorite were identified in very low-grade metaclastites from the Malàguide Complex (Betic Cordilleras, Spain), and studied by X-ray diffraction, and transmission and analytical electron microscopy. They occur both as small grains in the rock matrix, and associated with muscovitechlorite stacks. Transmission electron microscope observations revealed a transition from chlorite to ordered 1:1 interstratifications through complex 1:2 and 1:3 interstratifications. Analytical electron microscopy data indicate a composition slightly different from the sum of discrete trioctahedral chlorite and dioctahedral mica. The types of layer transitions suggest that mixed-layer formation included two main processes: (1) the replacement of a brucite sheet by a cation sheet in the chlorite structure; and (2) the precipitation of mica-like layers between the chlorite layers. The strongest diffraction lines in oriented X-ray patterns are: 12.60 Å (002), 7.98 Å (003), 4.82 Å (005) and 3.48 Å (007).

Palaeoweathering in slates from the Iberian Hercynian Massif (Spain): investigation by TEM of clay mineral signatures

Clay Minerals ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 435-451 ◽  
Author(s):  
M. A. Vicente ◽  
F. Elsass ◽  
E. Molina ◽  
M. Robert
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Climatic Conditions ◽  
Subtropical Climate ◽  
Lower Stage ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Tropical Areas ◽  
Well Differentiated ◽  
Confined Environment

AbstractPalaeoweathering profiles are widely represented in the Iberian meseta. Transmission electron microscopy (TEM) and analytical electron microscopy (AEM) were used to describe the mechanisms governing the processes involved in the formation of one of these weathering profiles developed over slates of the Iberian Hercynian Massif. Three well-differentiated weathering stages were distinguished, based upon well-defined mineralogical signatures characteristic of primary or secondary minerals. The lower stage is characterized by fresh green slates composed of Fe-chlorite, micas, quartz and feldspars. The soft slates represent an intermediate weathering stage. A confined environment has permitted the development of smectite from the different primary phyllosilicates, both by neoformation of montmorillonite and transformation into beidellite. In the upper part of the profile, the red slates are the most weathered. A tropical or subtropical climate has resulted in the formation of kaolinite and abundant iron oxides over several metres. The present study demonstrates that the three identified weathering stages were formed under the same climatic conditions. Such ‘toposequences’ are developed at the present time in tropical areas (Bocquier, 1971).

Evidence of a Precursor in the Neoformation of Palygorskite — New Data by Analytical Electron Microscopy

Clay Minerals ◽  
1994 ◽  
Vol 29 (2) ◽  
pp. 255-264 ◽  
Author(s):  
M. Suarez ◽  
J. M. Martin Pozas ◽  
M. Robert ◽  
F. Elsass
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Arid Environment ◽  
Relative Increase ◽  
Climatic Conditions ◽  
Early Diagenesis ◽  
Alluvial Fan ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Small Basin

AbstractThe rocks of the palygorskite deposit at Bercimuel (Segovia, Spain) have been studied by transmission electron microscopy and microanalysis. These rocks correspond to the zone of convergence of two alluvial fan systems that have filled the small basin of the River Riaza and would originally have been composed of illite and quartz silts. Among the accumulations of palygorskite it is possible to observe surrounded particles of micromicas that have undergone dissolution and opening thereby giving rise to disordered illite-smectite mixed-layer clays. This process continued up to the individualization of structural relics formed of units of 1–5 layers. At the same time, the chemical composition was modified with a loss of K and Al and a relative increase in Si and Mg, progressively evolving towards the composition of palygorskite. The paleogeographic position of the deposits, and the climatic conditions (arid environment), appear to be the dominant factors in the neoformation of palygorskite by alteration of the original sediments. The basic mineralogical process could be referred to as ‘early diagenesis’ in the formation of calcretes.

scholarly journals Advances and Applications of Atomic-Resolution Scanning Transmission Electron Microscopy

2021 ◽  
Vol 27 (5) ◽  
pp. 943-995
Author(s):  
Jingyue (Jimmy) Liu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Field Emission ◽  
Scanning Transmission Electron Microscopy ◽  
Electron Gun ◽  
Atomic Resolution ◽  
Single Atom ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

Although scanning transmission electron microscopy (STEM) images of individual heavy atoms were reported 50 years ago, the applications of atomic-resolution STEM imaging became wide spread only after the practical realization of aberration correctors on field-emission STEM/TEM instruments to form sub-Ångstrom electron probes. The innovative designs and advances of electron optical systems, the fundamental understanding of electron–specimen interaction processes, and the advances in detector technology all played a major role in achieving the goal of atomic-resolution STEM imaging of practical materials. It is clear that tremendous advances in computer technology and electronics, image acquisition and processing algorithms, image simulations, and precision machining synergistically made atomic-resolution STEM imaging routinely accessible. It is anticipated that further hardware/software development is needed to achieve three-dimensional atomic-resolution STEM imaging with single-atom chemical sensitivity, even for electron-beam-sensitive materials. Artificial intelligence, machine learning, and big-data science are expected to significantly enhance the impact of STEM and associated techniques on many research fields such as materials science and engineering, quantum and nanoscale science, physics and chemistry, and biology and medicine. This review focuses on advances of STEM imaging from the invention of the field-emission electron gun to the realization of aberration-corrected and monochromated atomic-resolution STEM and its broad applications.

High-resolution scanning electron microscopy

1987 ◽  
Vol 45 ◽  
pp. 530-533
Author(s):  
T. Nagatani
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Field Emission ◽  
Scanning Transmission Electron Microscope ◽  
Objective Lens ◽  
Second Development ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron

Although the main development of scanning electron microscopy (SEM) has been accomplished mostly by the Cambridge group and it has not been changed so much for about two decades, it should be noted that there have been two important developments to pursuing high resolution of better than 1nm.Most notably, use of a field emission gun developed by Crewe et al for the scanning transmission electron microscope (STEM) to form a fine electron beam has been most effective in SEMs due to its high brightness and low energy spread. Thus, several models of field emission (FE) SEMs have been developed in the early ’70s and commercialized with a resolution of 2∼3nm at around 30kV.The second development is to use a highly excited objective lens. The specimen has to be set inside the pole-pieces (so-called “in-lens” type).

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