High-Resolution, Low Voltage, Field-Emission Scanning Electron Microscopy (HRLVFESEM) Applications for Cell Biology and Specimen Preparation Protocols

2007 ◽  
pp. 145-169 ◽  
Author(s):  
Heide Schatten
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Field Emission ◽  
Cell Biology ◽  
Low Voltage ◽  
Specimen Preparation ◽  
Scanning Electron

Field Emission Scanning Electron Microscopy Studies of Industrial Polymers - A Survey

1998 ◽  
Vol 4 (S2) ◽  
pp. 814-815
Author(s):  
E.F. Osten ◽  
M.S. Smith
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
Structural Features ◽  
X Ray Diffraction ◽  
Styrene Acrylonitrile ◽  
Microscopy Techniques ◽  
Scanning Electron

We are using the term "Industrial Polymers" to refer to polymers [plastics] that are produced by the ton or (in the case of films) by the mile. For example, in descending order of world-wide use (tonnage), the top eight of these polymers are polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), styrene polymers (including polystyrene - PS, and acrylonitrile-butadienestyrene/ styrene-acrylonitrile - ABS/SAN), polyesters (PETP), polyurethane (PU), phenolics and aminoplastics.Industrial polymers, which have been produced by the millions of tons for the last five decades and are of obvious social and economic importance, have been exhaustively characterized. Structural features which affect physical properties and indicate process variables have been studied by many techniques other than microscopy (x-ray diffraction, thermal analysis, rheology, chromatographies, etc.). Microscopy techniques for polymer characterization have been well documented. Our motivation to apply field emission (high resolution) scanning electron microscopy to the study of polymers is: (1) The application of low voltage, high resolution SEM to biological materials is well characterized.

Structural Evidence for Actin-like Filaments in Toxoplasma gondii Using High-Resolution Low-Voltage Field Emission Scanning Electron Microscopy

2003 ◽  
Vol 9 (4) ◽  
pp. 330-335 ◽  
Author(s):  
Heide Schatten ◽  
L. David Sibley ◽  
Hans Ris
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Toxoplasma Gondii ◽  
Field Emission ◽  
Low Voltage ◽  
Protozoan Parasite ◽  
Cytoskeletal Network ◽  
Unicellular Organisms ◽  
Scanning Electron

The protozoan parasite Toxoplasma gondii is representative of a large group of parasites within the phylum Apicomplexa, which share a highly unusual motility system that is crucial for locomotion and active host cell invasion. Despite the importance of motility in the pathology of these unicellular organisms, the motor mechanisms for locomotion remain uncertain, largely because only limited data exist about composition and organization of the cytoskeleton. By using cytoskeleton stabilizing protocols on membrane-extracted parasites and novel imaging with high-resolution low-voltage field emission scanning electron microscopy (LVFESEM), we were able to visualize for the first time a network of actin-sized filaments just below the cell membrane. A complex cytoskeletal network remained after removing the actin-sized fibers with cytochalasin D, revealing longitudinally arranged, subpellicular microtubules and intermediate-sized fibers of 10 nm, which, in stereo images, are seen both above and below the microtubules. These approaches open new possibilities to characterize more fully the largely unexplored and unconventional cytoskeletal motility complex in apicomplexan parasites.

High-resolution scanning electron microscopy of carbon fiber

1989 ◽  
Vol 47 ◽  
pp. 704-705
Author(s):  
Deborah L. Vezie
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Carbon Fiber ◽  
Field Emission ◽  
Carbon Fibers ◽  
Low Voltage ◽  
Electron Gun ◽  
Scanning Electron

As part of an extensive study of polyacrylonitrile (PAN) and mesophase pitch-based carbon fibers, high resolution scanning electron microscopy (HRSEM) is shown to provide additional insight into understanding and modelling microstructural origins of mechanical properties of carbon fiber. Although carbon fiber has been studied extensively, no sufficiently clear relationship between structure and mechanical properties such as elastic modulus and compressive strength has yet been developed from quantitative TEM and WAXS investigations.In this study, HRSEM data of selected carbon fibers is used to illustrate the power of HRSEM to elucidate structural differences likely accounting for changes in mechanical properties not sensitively probed either by TEM or WAXS. The three-dimensional nature of SEM imaging with accompanying high resolution permits a clearer visualization and more detailed examination of regional structures within carbon fiber over two-dimensional TEM and globally averaged WAXS data.The design of the high resolution, field emission SEM permits low voltage imaging of poorly conducting samples with resolution an order of magnitude greater than a conventional tungsten hairpin filament SEM under the same operating voltage and sample preparation conditions. Although carbon fiber is a relatively conductive material, charging effects can be seen in uncoated PAN fibers above 3.0 keV in a conventional SEM. Lower accelerating voltages are necessary for uncoated imaging of these fibers, but become impractical due to degradation of conventional SEM performance at these voltages. Uncoated sample imaging is preferred to prevent conventional evaporation or sputter coating techniques from obscuring or altering the sample surface, although charging effects may then be a problem. The high resolution, field emission SEM solves these competing voltage/ charging/ resolution issues for poorly conducting materials with the very nature of its design; the high brightness of the electron gun at low voltage coupled with the “in lens” sample placement and above the objective lens detector dramatically improve the resolution of these instruments, especially at low voltage.

Three Dimensional Imaging of Light Metals Using Serial Block Face Scanning Electron Microscopy (SBFSEM)

2013 ◽  
Vol 765 ◽  
pp. 501-505 ◽  
Author(s):  
Teruo Hashimoto ◽  
George E. Thompson ◽  
Michele Curioni ◽  
Xiao Rong Zhou ◽  
Peter Skeldon
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Low Voltage ◽  
Three Dimensional ◽  
Specimen Preparation ◽  
Light Metals ◽  
Metallic Materials ◽  
Block Face ◽  
Scanning Electron

Ultramicrotomy is used extensively as a specimen preparation method for transmission electron microscopy (TEM) in the biological and polymer fields, where relatively soft materials are sectioned to generate electron transparent specimens. Additionally, in corrosion control studies of light metals, e.g. aluminium and magnesium and their alloys, ultramictrotomy has been progressed at Manchester for characterisation of the metallic materials and their filming behaviour as well as the propagation of corrosion into the material interior at selected sites. The benefits of ultramicrotomy include the ability to generate uniform thicknesses of multiphase specimens with relatively large observation areas that include, for example, randomly distributed intermetallic particles in the alloy. However, mechanical sectioning with a diamond knife generates artefacts that include chattering and local damage; localised corrosion of the thin slices may also result from their residence on a water bath at the rear of the knife prior to collection for TEM study. Recently, ultramicrotomy has also been utilised to assist high resolution imaging in the scanning electron microscope (SEM); the generation of relatively flat specimens removes roughness effects from the secondary electron signal and improves the backscattered electron yield due to removal of an oxidised or carbon contaminated surface. The combination of ultramicrotomy and low voltage scanning electron microscopy has also enabled generation of high resolution, three dimensional images using sectioning and subsequent imaging of the fresh surface by SEM. However, importantly, recent instrumental developments, i.e. the GATAN 3View System, now enable ultramicrotomy to be performed in-SEM. Consequently, rapid in-SEM sectioning and imaging can now be undertaken with ready reconstruction of electron tomographs for light metallic materials. Here, the application of the Gatan 3View system in a Quanta 250 FEG-ESEM is presented, with consideration of artefacts introduced by the electron beam for serial block face sectioning imaging of light alloys.

Imaging of polymer single crystals in low-voltage, high-resolution scanning electron microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 1106-1107
Author(s):  
W.W. Adams ◽  
G. Price ◽  
A. Krause
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Single Crystals ◽  
Low Voltage ◽  
Polymer Surface ◽  
Beam Current ◽  
Image Features ◽  
First Results ◽  
Scanning Electron

It has been shown that there are numerous advantages in imaging both coated and uncoated polymers in scanning electron microscopy (SEM) at low voltages (LV) from 0.5 to 2.0 keV compared to imaging at conventional voltages of 10 to 20 keV. The disadvantages of LVSEM of degraded resolution and decreased beam current have been overcome with the new generation of field emission gun SEMs. In imaging metal coated polymers in LVSEM beam damage is reduced, contrast is improved, and charging from irregularly shaped features (which may be unevenly coated) is reduced or eliminated. Imaging uncoated polymers in LVSEM allows direct observation of the surface with little or no charging and with no alterations of surface features from the metal coating process required for higher voltage imaging. This is particularly important for high resolution (HR) studies of polymers where it is desired to image features 1 to 10 nm in size. Metal sputter coating techniques produce a 10 - 20 nm film that has its own texture which can obscure topographical features of the original polymer surface. In examining thin, uncoated insulating samples on a conducting substrate at low voltages the effect of sample-beam interactions on image formation and resolution will differ significantly from the effect at higher accelerating voltages. We discuss here sample-beam interactions in single crystals on conducting substrates at low voltages and also present the first results on HRSEM of single crystal morphologies which show some of these effects.

Pre-Meeting Topical Conference

2002 ◽  
Vol 8 (I1) ◽  
pp. 20-20
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Voltage ◽  
Ion Beam ◽  
Analytical Electron Microscopy ◽  
Polymeric Materials ◽  
Specimen Preparation ◽  
Microbeam Analysis ◽  
Scanning Electron

Topic: Characterization of Non-Conductive or Charging Materials by Microbeam AnalysisThe goal of this topical conference is to present the state of the art for materials characterization of non-conductive or charging materials using microbeam analysis. Examples of charging materials include polymeric materials, ceramic materials, and photoresist materials in the microelectronic industry. Also, the characterization of biological specimens will be covered because they are prone to problems related to charging. These materials are of great technological importance and their characterization is still a great challenge because they charge when analyzed with an electron beam. The techniques of microbeam analysis that will be considered are: X-ray Microanalysis in the Electron Microprobe, Low Voltage Scanning Electron Microscopy, Environmental Scanning Electron Microscopy, Analytical Electron Microscopy with Field Emission Transmission Electron Microscopy, and Focused Ion Beam Milling for specimen preparation. World experts will present papers on these topics. Papers from this topical conference will be published in a special issue of Microscopy & Microanalysis.

High-Resolution Field Emission Scanning Electron Microscopy (FESEM) Imaging of Cellulose Microfibril Organization in Plant Primary Cell Walls

2017 ◽  
Vol 23 (5) ◽  
pp. 1048-1054 ◽  
Author(s):  
Yunzhen Zheng ◽  
Daniel J. Cosgrove ◽  
Gang Ning
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Wall ◽  
High Resolution ◽  
Field Emission ◽  
Cell Walls ◽  
Cellulose Microfibrils ◽  
Critical Point Drying ◽  
Sputter Coating ◽  
Scanning Electron

AbstractWe have used field emission scanning electron microscopy (FESEM) to study the high-resolution organization of cellulose microfibrils in onion epidermal cell walls. We frequently found that conventional “rule of thumb” conditions for imaging of biological samples did not yield high-resolution images of cellulose organization and often resulted in artifacts or distortions of cell wall structure. Here we detail our method of one-step fixation and dehydration with 100% ethanol, followed by critical point drying, ultrathin iridium (Ir) sputter coating (3 s), and FESEM imaging at a moderate accelerating voltage (10 kV) with an In-lens detector. We compare results obtained with our improved protocol with images obtained with samples processed by conventional aldehyde fixation, graded dehydration, sputter coating with Au, Au/Pd, or carbon, and low-voltage FESEM imaging. The results demonstrated that our protocol is simpler, causes little artifact, and is more suitable for high-resolution imaging of cell wall cellulose microfibrils whereas such imaging is very challenging by conventional methods.

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