A Comparison of Scanning and Fixed Beam High Voltage Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 6-7
Author(s):  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Scanning Transmission Electron Microscope ◽  
Recording Time ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
High Voltage Supply ◽  
Fixed Beam

Since the theoretical advantage of high voltage microscopy in terms of improved resolution has not yet been achieved, the justification for the building of high voltage microscopes has been mainly the possibility of studying thicker specimens plus the observation of some radiation damage and some relativistic n-beam dynamical diffraction effects. For most of these purposes the scanning mode of transmission electron microscopy has clear advantages.As in the case of the fixed beam instrument (FBI), the limitation on resolution of the scanning transmission electron microscope (STEM) for ideal thin specimens is determined largely by instabilities of the high voltage supply and lens currents and by mechanical instabilities. In this respect the STEM suffers from the disadvantage that the point-by-point recording of the image involves a greater recording time and hence greater sensitivity to long term instabilities.

scholarly journals Some Current and Future Trends of High Voltage Transmission Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 2-3
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Materials Science ◽  
Future Trends ◽  
Light Elements ◽  
Special Effects ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Transmission Electron ◽  
Resolution Level

The Optimum Voltages for Electron Microscopy – The advantages of high voltage electron microscopy are now well established, and many applications, such as use of environmental cells both in metallurgy and biology, are now possible. However recent experiments at Toulouse indicate that except for light elements, there is no appreciable gain in transmission for a given resolution level as the energy is increased above 1 MeV (see Fig. 1). These results are not as optimistic as theory might indicate. Special effects such as critical voltages above 1 MeV are of interest, but knock-on radiation damage imposes limitations on many applications. Thus it would appear that 1 MeV is a reasonable upper limit for most applications in materials science.

Observations on Developing Blood Vessels in Rat Spinal Cord—A High Voltage Electron Microscopy Study

1974 ◽  
Vol 32 ◽  
pp. 66-67
Author(s):  
Richard S. Hannah
Keyword(s):  
Electron Microscopy ◽  
Spinal Cord ◽  
High Voltage ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
High Voltage Electron Microscopy ◽  
Thin Sections ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Transmission Electron

The formation of junctional complexes between endothelial cell processes was examined in rat spinal cords, from age birth to six weeks. Segments of spinal cord were removed from the region of the cervical enlargement and fixed. For comparative purposes, animals from each time group were subdivided into groups, fixed by either immersion or perfusion with an aldehyde combination in sodium cacodylate buffer and embedded in Araldite. Thin sections were examined by conventional transmission electron microscopy. Thick sections (0.5μ - 1.0μ) were stained with uranyl magnesium acetate for four hours at 60°C and lead citrate for 30 mins. and examined in the AEI Mark II High Voltage Electron Microscope.

Detection efficiency and estimation of the performance of high voltage STEM

1978 ◽  
Vol 36 (1) ◽  
pp. 84-85
Author(s):  
A. Ishikawa ◽  
C. Morita ◽  
M. Hibino ◽  
S. Maruse
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
High Voltage ◽  
Detection Efficiency ◽  
Beam Current ◽  
High Energy ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Transmission Electron

One of the problems which are met in conventional transmission electron microscopy (CTEM) at high voltages is the reduction of the sensitivity of photographic films for high energy electron beams, resulting in the necessity of using high beam current. This cancels out an advantage of high voltage electron microscopy which is otherwise expected from the reduction of the inelastic scattering in the specimen, that is the reduced radiation damage of the specimen during observations. However, it is expected that the efficiency of the detector of scanning transmission electron microscopy (STEM) can be superior to that of CTEM, since the divergence of the electron beam in the detecting material does not affect the quality of the image. In addition to observation with less radiation damage, high voltage STEM with high detection efficiency is very attractive for observations of weak contrast objects since the enhancement of the contrast (which is an important advantage of STEM) is easily realized electrically.

Integrated microscopy resource for biomedical research at the university of wisconsin at madison

1987 ◽  
Vol 45 ◽  
pp. 594-597 ◽  
Author(s):  
G. Schatten ◽  
J. Pawley ◽  
H. Ris
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
High Voltage ◽  
Biomedical Research ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
University Of Wisconsin ◽  
Transmission Electron ◽  
The University

The High Voltage Electron Microscopy Laboratory [HVEM] at the University of Wisconsin-Madison, a National Institutes of Health Biomedical Research Technology Resource, has recently been renamed the Integrated Microscopy Resource for Biomedical Research [IMR]. This change is designed to highlight both our increasing abilities to provide sophisticated microscopes for biomedical investigators, and the expansion of our mission beyond furnishing access to a million-volt transmission electron microscope. This abstract will describe the current status of the IMR, some preliminary results, our upcoming plans, and the current procedures for applying for microscope time.The IMR has five principal facilities: 1.High Voltage Electron Microscopy2.Computer-Based Motion Analysis3.Low Voltage High-Resolution Scanning Electron Microscopy4.Tandem Scanning Reflected Light Microscopy5.Computer-Enhanced Video MicroscopyThe IMR houses an AEI-EM7 one million-volt transmission electron microscope.

Development of Field Emission Gun for High Voltage Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 604-605
Author(s):  
H. Shimoyama ◽  
C. Morita ◽  
S. Arai ◽  
N. Yokoi ◽  
K. Miyauchi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Field Emission ◽  
High Voltage ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Transmission Electron ◽  
Scanning Transmission

For the last few years we have been developing a field emission (FE) gun system for our high voltage electron microscope (HVEM) H-1250 ST (maximum accelerating voltage of 1.25 MV) at Nagoya University, in order to attain much higher level of performance of the instrument and to exploit further extended field of application. In the first stage of the project during the period from 1986 to 1987, the FE gun system had been mounted on the top of the accelerating tube, and successfully been operated at the accelerating voltage of 1 MV for the first time pin the world. The operation was very stable and high resolution images for both scanning transmission electron microscopy (STEM) and conventional transmission electron microscopy (CTEM) modes were possible at this stage. At the same time, however, several practical problems related to incorporating the FE gun into the HVEM were made clear. Since then several important modifications on instrumentation and electronics have been made and the project is now at the second stage. In this paper a brief outline of the FE gun system developed for our HVEM is described especially from the view point of instrumentation and electronics.

scholarly journals High Voltage Microscopy in Paleontological Studies – Graptolites

1970 ◽  
Vol 28 ◽  
pp. 492-493
Author(s):  
W. B. N. Berry ◽  
R. S. Takagi ◽  
G. Thomas ◽  
D. J. Jurica
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
The Other ◽  
Transmission Power ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Transmission Electron ◽  
Thin Sectioning ◽  
Electron Microscopes ◽  
Biological Methods

Transmission electron microscopy has seldom been used in studies of fossils, and to date, no electron diffraction work has been reported. Because of the limited transmission power of the 100 kV electron microscopes (<lμ), the techniques which have been used to prepare specimens have followed standard biological methods, including ultra-thin sectioning and staining. High voltage electron microscopy on the other hand allows examination of considerably thicker specimens (up to 5μ at 500 kV) and is particularly useful in studying fossils e.g. it is often not necessary to section pieces of the fossil. Minimal preparation is advantageous because materials that have been interred in rocks of the earth's crust for millions of years are commonly brittle and distort or break while being sectioned with the microtome.

High Voltage Electron Microscopy of Ion-Milled Dental Enamel

1974 ◽  
Vol 32 ◽  
pp. 60-61
Author(s):  
L. D. Ackerman ◽  
S. H. Y. Wei
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Third Molar ◽  
Polarized Light ◽  
Dental Enamel ◽  
Longitudinal Section ◽  
Ion Milling ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.

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