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.

Comparative High-Resolution X-Ray Diffraction Analysis of GaN/AlGaN Heterostructure on Al2O3 and Si (111) Substrate Grown by Plasma Assisted Molecular Beam Epitaxy

2015 ◽  
Vol 1754 ◽  
pp. 129-134
Author(s):  
Sanjay Kr. Jana ◽  
Saptarsi Ghosh ◽  
Syed Mukulika Dinara ◽  
Apurba Chakraorty ◽  
D. Biswas
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Field Emission ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
Reciprocal Space Mapping ◽  
X Ray ◽  
Scanning Electron

AbstractThe work presents a comparative study on GaN/AlGaN type-II heterostructures grown on c-plane Al2O3 and Si (111) substrates by Plasma Assisted Molecular Beam Epitaxy. The in-depth structural characterizations of these samples were performed by High-Resolution X-Ray Diffraction, X-ray Reflectivity and Field Emission Scanning Electron Microscopy. The in-plane and out-of plane strains were determined from measured c- and a-lattice parameters of the epilayers from reciprocal space mapping of both symmetric triple axis (002) and asymmetric grazing incidence (105) double axis mode. The mosaicity parameters like tilt and correlation lengths were also calculated from reciprocal space mapping. Moreover, the twist angle was measured from skew symmetric off axis scan of (102), (103), and (105) planes along with (002) symmetric plane. The defect density were measured from the full width at half maxima of skew symmetric scan of (002) and (102) reflection planes. Also, the strained states of all the layers were analyzed and corresponding Al mole fraction was calculated based on anisotropic elastic theory. The thicknesses of the layers were measured from simulation of the nominal structure by fitting with X-ray Reflectivity experimental curves and also by comparing with cross sectional Field Emission Scanning Electron Microscopy micrographs.

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.

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.

Wood identification of charcoal with 3D-reflected light microscopy

IAWA Journal ◽  
2020 ◽  
Vol 41 (4) ◽  
pp. 478-489 ◽  
Author(s):  
Valentina Zemke ◽  
Volker Haag ◽  
Gerald Koch
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Field Emission ◽  
Polarized Light ◽  
Structural Features ◽  
Light Illumination ◽  
Reflected Light ◽  
Carbonized Wood ◽  
Scanning Electron

Abstract The present study focusses on the application of 3D-reflected light microscopy (3D-RLM) for the wood anatomical identification of charcoal specimens produced from domestic and tropical timbers. This special microscopic technique offers a detailed investigation of anatomical features in charcoal directly compared with the quality of field emission scanning electron microscopy (FESEM). The advantages of using the 3D-RLM technology are that fresh fracture planes of charcoal can be directly observed under the microscope without further preparation or surface treatment. Furthermore, the 3D-technique with integrated polarized light illumination creates high-contrast images of uneven and black charcoal surfaces. Important diagnostic structural features such as septate fibres and intercellular canals can be clearly detected and intervessel pits are directly measured. The comparison of the microscopic analyses reveals that 3D-reflected light microscopy (3D-RLM) provides an effective alternative technique to conventional field emission scanning electron microscopy for the identification of carbonized wood.

scholarly journals Nickel-Doped Cerium Oxide Nanoparticles: Green Synthesis Using Stevia and Protective Effect against Harmful Ultraviolet Rays

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4424 ◽  
Author(s):  
Mehrdad Khatami ◽  
Mina Sarani ◽  
Faride Mosazadeh ◽  
Mohammadreza Rajabalipour ◽  
Alireza Izadi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cerium Oxide ◽  
Field Emission ◽  
Cerium Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
X Ray Diffraction ◽  
Ni Doping ◽  
X Ray ◽  
Scanning Electron

Nanoparticles of cerium oxide CeO2 are important nanomaterials with remarkable properties for use in both industrial and non-industrial fields. In a general way, doping of oxide nanometric with transition metals improves the properties of nanoparticles. In this study, nickel- doped cerium oxide nanoparticles were synthesized from Stevia rebaudiana extract. Both doped and non-doped nanoparticles were characterized by X-ray diffraction, Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray, Raman spectroscopy, and Vibrating-Sample Magnetometry analysis. According to X-ray diffraction, Raman and Energy Dispersive X-ray crystalline and single phase of CeO2 and Ni doped CeO2 nanoparticles exhibiting fluorite structure with F2g mode were synthesized. Field Emission Scanning Electron Microscopy shows that CeO2 and Ni doped nanoparticles have spherical shape and sizes ranging of 8 to 10 nm. Ni doping of CeO2 results in an increasing of magnetic properties. The enhancement of ultraviolet protector character via Ni doping of CeO2 is also discussed.

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