“High Resolution High Voltage Electron Microscopy”

1968 ◽  
Vol 26 ◽  
pp. 326-327
Author(s):  
Benjamin M. Siegel
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Voltage ◽  
Full Potential ◽  
Contrast Imaging ◽  
High Voltage Electron Microscopy ◽  
Low Contrast ◽  
Voltage Electron ◽  
Critical Areas ◽  
High Voltage Electron

The potential advantages of high voltage electron microscopy for extending the limits of resolution and contrast in imaging low contrast objects, such as biomolecular specimens, is very great. The results of computations will be presented showing that at accelerating voltages of 500-1000 kV it should be possible to achieve spacial resolutions of 1 to 1.5 Å and using phase contrast imaging achieve adequate image contrast to observe single atoms of low atomic number.The practical problems associated with the design and utilization of the high voltage instrument are, optimistically, within the range of competence of the state of the art. However, there are some extremely important and critical areas to be systematically investigated before we have achieved this competence. The basic electron optics of the column required is well understood, but before the full potential of an instrument capable of resolutions of better than 1.5 Å are realized some very careful development work will be required. Of great importance for the actual achievement of high resolution with a high voltage electron microscope is the fundamental limitation set by the characteristics of the high voltage electron beam that can be obtained from the accelerator column.

Advances in High Voltage Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 8-9
Author(s):  
L. E. Thomas ◽  
J. S. Lally ◽  
R. M. Fisher
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Contrast Imaging ◽  
High Voltage Electron Microscopy ◽  
Direct Beam ◽  
Diffraction Contrast ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Maximum Transmission

Diffraction contrast imaging in a HVEM differs from 100 kv electron microscopy mainly because of the increased importance of many-beam interactions among the systematic reflections from a given set of low index planes. Since the last annual EMSA meeting our understanding of the consequences of these interactions, in particular the marked changes in the diffraction conditions which give optimum transmission and defect contrast, has advanced rapidly. Progress in a number of related areas will be described.Transmission - Throughout the range 100-1000 kv maximum transmission occurs when the crystal is oriented for systematic diffraction from the lowest index reflecting planes. Relatively poor transmission always results when nonsystematic reflections are simultaneously excited. At 100 kv the Bragg deviation which maximizes transmission in the direct beam is just positive of the 1st order Bragg position, at k ∼ 0.6.

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.

Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain

1977 ◽  
Vol 35 ◽  
pp. 570-571 ◽  
Author(s):  
Lee D. Peachey ◽  
Clara Franzini-Armstrong
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Three Dimensional ◽  
Biological Tissues ◽  
High Voltage Electron Microscopy ◽  
Transverse Tubular System ◽  
Peroxidase Reaction ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
T System

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.

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