High resolution Scanning Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 6-7
Author(s):  
David C. Joy
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
High Performance ◽  
Secondary Electron ◽  
Wide Energy Range ◽  
Wide Energy ◽  
Electron Microscopes ◽  
Electron Imaging ◽  
Scanning Electron

High resolution scanning electron microscopy is still a relatively new and unfamiliar concept because in the early days of the SEM it was expected, that secondary electron imaging would be limited to a resolution of between 5 and 10nm at best. Now, however, because of improvements in instrumentation and technique based on advances in the understanding of electron beam interactions with solids current SEMs can demonstrate spatial resolutions below 1nm, rivaling those obtained by transmission instruments.High performance scanning electron microscopes always incorporate two advanced items of instrumentation. Firstly they use field emission guns (FEGs). The high brightness, low energy spread, and small source size of the FEG makes it possible to produce an electron probe of sub-nanometer size which contains sufficient current for secondary electron imaging (i.e 10-12 amps or more) and which can maintain this performance over a wide energy range (3 to 30keV). Secondly, the new high performance instruments place the specimen within a high excitation, immersion, probe forming lens.

Scanning Electron Microscopy and Secondary-Electron Imaging Microscopy

2012 ◽  
pp. 2280-2280
Author(s):  
Yimei Zhu ◽  
Hiromi Inada ◽  
Achim Hartschuh ◽  
Li Shi ◽  
Ada Della Pia ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Secondary Electron ◽  
Electron Imaging ◽  
Scanning Electron

Validation of George and Robinson SE-I Signal Theorem. Implications for Ultrahigh Resolution Sem on Bulk Untilted Specimens

1982 ◽  
Vol 40 ◽  
pp. 368-369 ◽  
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Scattering ◽  
Secondary Electron ◽  
Ultrahigh Resolution ◽  
Secondary Electrons ◽  
Electron Imaging ◽  
Scanning Electron

In scanning electron microscopy on bulk untilted specimens topographic resolution in conventional “secondary electron imaging” (SEI) mode is very low; only in the order of several beam diameters. Extensive electron scattering within the specimen was thought to limit resolution since secondary electrons (SE) are collected irrespectively of their origin.

Secondary Electron Imaging of Liquid Water Films in the Environmental Scanning Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 374-375
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Liquid Water ◽  
Secondary Electron ◽  
Gas Pressure ◽  
Aqueous Environment ◽  
Water Films ◽  
Electron Imaging ◽  
Scanning Electron ◽  
Gas Pressures

High gas pressure scanning electron microscopy is now routinely possible with new microscopes operating between 0.1 and 20 torr gas pressure. Since the specimen chamber is separated from the electron optical column by pressure-limiting apertures, high gas pressures present at the level of the specimen do not affect the high vacuum in the column. The use of a single PLA underneath the last probe-forming lens allows maintainance of ∼0.1 torr. Twenty torr can be stabilized with two PLA, forming two differentially pumped pressure zones which may be incorporated into the last probe-forming lens.One of the most important new features of high gas pressure microscopy is the possibility to alter the type of gas and its pressure over a large range. High gas pressures (>1 torr) are required for charge neutralization on rugged insulators and for gas amplification of the SE signal. Additionally, using water vapors, liquid water can be stabilized. However, the aqueous environment is only one example among many possibilities.The secondary electron imaging of liquid water is a fascinating new aspect of scanning electron microscopy. At saturated water vapor pressures, water is stable indefinitely. Increasing or decreasing the vapor pressure allows condensation or evaporation of water and provides means to generate water films. As can be seer from Fig. 1, the stabilizing pressure for water at 20°C is 17.5 torr. Such a pressure would require a very short working distance for SE imaing. Therefore, it is preferable to reduce the specimen temperature and to establish vapor saturation at lower pressures. However, liquid water can only be stabilized at pressures greater than ∼4.5 torr.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

Scanning Electron Microscopy-cuticular Lesions on the Roundworm Ascaris Suum

1970 ◽  
Vol 28 ◽  
pp. 114-115
Author(s):  
P. A. Madden ◽  
W. R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Freeze Drying ◽  
Room Temperature ◽  
Secondary Electron ◽  
Distilled Water ◽  
Freeze Dried ◽  
Silver Paint ◽  
To Come ◽  
Scanning Electron

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.

Examination of Schistosome Cercariae and Schistosomules by Scanning Electron Microscopy

1969 ◽  
Vol 27 ◽  
pp. 50-51
Author(s):  
D. Johnson ◽  
P. Moriearty
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Light Microscopy ◽  
Surface Structure ◽  
Extensive Study ◽  
Scanning Microscopy ◽  
Host Parasite ◽  
Conventional Electron Microscopy ◽  
Scanning Electron

Since several species of Schistosoma, or blood fluke, parasitize man, these trematodes have been subjected to extensive study. Light microscopy and conventional electron microscopy have yielded much information about the morphology of the various stages; however, scanning electron microscopy has been little utilized for this purpose. As the figures demonstrate, scanning microscopy is particularly helpful in studying at high resolution characteristics of surface structure, which are important in determining host-parasite relationships.

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