Application of high-pressure scanning electron microscopy (ECO-SEM) in forensic sample analysis

1996 ◽  
Vol 54 ◽  
pp. 848-849
Author(s):  
Thomas A. Kubic ◽  
JoAnn Buscaglia
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Carbon Coating ◽  
High Vacuum ◽  
Controlled Environment ◽  
Sample Analysis ◽  
Sample Chamber ◽  
Forensic Sample ◽  
Scanning Electron

Traditionally to obtain satisfactory images and reasonable resolution with a Scanning Electron Microscope (SEM), it has been necessary to employ a high vacuum within the sample chamber.High vacuum can result in the dehydration of materials with an alteration of sample morphology and in some cases the introduction of artifacts. In such an environment, samples that are nonconductive experience extensive charging with image degradation. Samples of forensic concern, such as textile bundles or swatches, exhibit this problem even after the application of metal coating. The problem is even more pronounced when carbon coating is used, as is often the preference of forensic microscopists in order to simplify interpretation of the EDX spectra.The commercial availability of "high pressure" or controlled environment SEMs that operate with sample chamber pressures from 50 to 4000 millitorr, while the electron guns and columns are kept at high vacuum conditions have solved these problems. The presence of this "higher" pressure retards dehydration while charging effects are nearly eliminated.

Scattering of Electrons at High - Pressure and Restoration of Image Contrast in High Pressure Scanning Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 384-385
Author(s):  
J. S. Shah ◽  
R. Durkin ◽  
A. N. Farley
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Cross Sections ◽  
Single Scattering ◽  
Image Contrast ◽  
Experimental Scheme ◽  
Medium Resolution ◽  
Scattering Approximation ◽  
Scanning Electron

It is now possible to perform High Pressure Scanning Electron Microscopy (HPSEM) in the range 10 to 2000 Pa. Here the effect of scattering on resolution has been evaluated by calculating the profile of the beam in high pressure and assessing its effect on the image contrast . An experimental scheme is presented to show that the effect of the primary beam ionization is to reduce image contrast but this effect can be eliminated by a novel use of specimen current detection in the presence of an electric field. The mechanism of image enhancement is discussed in terms of collection of additional carriers generated by the emissive components.High Pressure SEM (HPSEM) instrumentation is establishing itself as commercially viable. There are now a number of manufacturers, such as JEOL, ABT, ESCAN, DEBEN RESEARCH, selling microscopes and accessories for HPSEM. This is because high pressure techniques have begun to yield high quality micrographs at medium resolution.To study the effect of scattering on the incident electron beam, its profile - in a high pressure environment - was evaluated by calculating the elastic and inelastic scattering cross sections for nitrogen in the energy range 5-25 keV. To assess the effect of the scattered beam on the image contrast, the modification of a sharp step contrast function due to scattering was calculated by single scattering approximation and experimentally confirmed for a 20kV accelerated beam.

XRPD and Scanning Electron Microscopy of Alloys of the CuAlS2 – CuFeS2 System Prepared by Thermobaric Treatment

MRS Advances ◽  
2018 ◽  
Vol 3 (56) ◽  
pp. 3323-3328
Author(s):  
Barys Korzun ◽  
Anatoly Pushkarev
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Lattice Constants ◽  
Scanning Electron

ABSTRACTAlloys of the CuAlS2 – CuFeS2 system were prepared by thermobaric treatment at high pressure of 5.5 GPa and temperatures ranging from 573 to 1573 K and phase formation in the system was investigated using X-ray powder diffraction, optical microscopy and scanning electron microscopy equipped with energy dispersive spectroscopy. The unit-cell parameters (the lattice constants and the unit-cell volume) were computed as a function of the composition. Absence of complete solubility in the (CuAlS2)1-x-(CuFeS2)x system was established. Formation of solid solutions with the tetragonal structure of chalcopyrite was detected for compositions with the molar part of CuFeS2 x not exceeding 0.10.

Purification of SWNTs Using Microwave Heating

2001 ◽  
Vol 706 ◽  
Author(s):  
Avetik R. Harutyunyan ◽  
Bhabendra K. Pradhan ◽  
Gamini U. Sumanasekera ◽  
Jiping Chang ◽  
Gugang Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Microwave Heating ◽  
Acid Treatment ◽  
Carbon Coating ◽  
Single Wall Carbon Nanotubes ◽  
Metal Catalyst ◽  
Thermo Gravimetric ◽  
Mild Acid ◽  
Scanning Electron

AbstractA new method for purifying single wall carbon nanotubes (SWNTs) using microwave heating is developed. The microwaves couple to the residual metal catalyst, raising significantly the local temperature leading to both the oxidation and rupturing of the carbon passivation layer over the metal catalyst particles and sintering. With this protective carbon coating weakened or removed, a mild acid treatment in HCl is then sufficient to remove most of the metal in the sample, leaving the nanotubes in tact. Results from transmission and scanning electron microscopy (TEM & SEM), Raman spectroscopy and thermo-gravimetric studies are discussed.

Failure Analysis of High Pressure Container using Fractography and Material Morphology

2018 ◽  
Vol 773 ◽  
pp. 287-291
Author(s):  
Eui Soo Kim
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Failure Analysis ◽  
Large Scale ◽  
Chemical Properties ◽  
Accurate Analysis ◽  
Internal Pressures ◽  
Scanning Electron ◽  
And Chemical Properties

High-pressure gas containers must be able to withstand high internal pressures because they store compressed gases. Otherwise, cracks or defects may lead to an explosion, which may in turn lead to a large-scale disaster. Therefore, accurate analysis of the causes of cracks or defects and various techniques for detecting cracks or defects are needed. In this research, we analyzed the failure mechanism of a high-pressure gas container through fractography using scanning electron microscopy and optical microscopy and through measurements of their mechanical and chemical properties.

Morphology of the lateral fields of the infective juvenile of the entomopathogenic family Steinernematidae (Nematoda) using high pressure freezing (HPF)

Nematology ◽  
2019 ◽  
Vol 22 (1) ◽  
pp. 69-74
Author(s):  
Zdeněk Mráček ◽  
Jiří Nermut’ ◽  
Martina Tesařová ◽  
Vladimír Půža
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Infective Juvenile ◽  
Field Pattern ◽  
Taxonomic Character ◽  
High Pressure Freezing ◽  
Lateral Field ◽  
Transmission Electron ◽  
Scanning Electron

Summary The lateral field pattern of infective juveniles of the nematode family Steinernematidae is an important taxonomic character. Scanning electron microscopy (SEM) shows the number of ridges and lines or incisures clearly, but does not provide other details. In the present study, ten species from six clades of Steinernematidae have been studied for their lateral field morphology using SEM and high pressure freezing (HPF) with transmission electron microscopy (TEM). Both methods indicated the same number of ridges and lines, although HPF/TEM resulted in a more detailed morphology with differences between the species. The tips of the ridges are either finely rounded or pointed and the lines are V-shaped or have a broadened bottom. These characters represent an additional pattern that may be characteristic for some species within the phylogenetic clades. Further studies of the lateral field morphology of other species is needed to ascertain whether each pattern is clade specific and phylogenetically valuable.

Environmental SEM in a Multi-User Biological Sciences E.M. Unit

1999 ◽  
Vol 5 (S2) ◽  
pp. 286-287
Author(s):  
Christopher J. Gilpin ◽  
Mohamed S. Baguneid
Keyword(s):  
Biological Sciences ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Vacuum ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Environmental Sem ◽  
Imaging Mechanisms ◽  
Scanning Electron ◽  
The Ideal

Environmental scanning electron microscopy (ESEM) has matured into a mainstream technique in many areas of microscopy. Instrumentation has evolved and our understanding of some of the imaging mechanisms has progressed. However the majority of laboratories where ESEMs are located are based around the materials sciences. Despite the fact that ESEM is the only SEM instrument that permits liquid water to be present whilst imaging, the housing of such a microscope in biological EM units has been relatively rare. This authors laboratory is a multi-user EM unit based in a School of Biological Sciences. There exists the opportunity for basic biological scientists, clinical and pre-clinical medical and dental researchers to make use of such a resource. Indeed as the ESEM is housed alongside a conventional high vacuum instrument and a cryo high vacuum instrument there exists the ideal opportunity to carry out comparative studies.This study will examine a range of biological samples using ESEM, cryo SEM and dry high vacuum SEM.

Characteristics of Micro/Nanopores and Their Petroleum Significance in the Eastern Segment of the Altun Piedmont, Qaidam Basin, Western China

2021 ◽  
Vol 21 (1) ◽  
pp. 181-194
Author(s):  
Qing-Bin Xie ◽  
Xin Li ◽  
Chuan-Long Li ◽  
Yong-Shu Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Pressure ◽  
Field Emission ◽  
Qaidam Basin ◽  
Western China ◽  
Tight Sandstone ◽  
Eastern Segment ◽  
Scanning Electron ◽  
Nuclear Magnetic

With continuous improvements in nanotechnology, the development of micro/nanoscale pores and fractures in reservoirs can be more clearly identified, and great progress has been made in tight sandstone and shale. Bedrock has an ultralow porosity and is a reservoir with low permeability. To study the characteristics of micro/nanoscale pore development and reveal their petroleum significance in the eastern segment of the Altun Piedmont, research has been conducted with the use of cathodoluminescence, field emission scanning electron microscopy and energy spectrum analysis, formation microresistivity image logging, high-pressure mercury injection and nuclear magnetic logging. The results have shown that the porosity of the bedrock reservoir in the eastern segment of the Altun Piedmont, as measured by helium injection and nuclear magnetic logging, is between 0.004% and 9.76%, the average porosity is between 1.663% and 3.844%, and the permeability is between the maximum of 0.002 mD and 33.239 mD. The average permeability is between 0.02 mD and approximately 3.836 mD. Micro/nanopores are generally developed, with the majority being intragranular micro/nanopores, intercrystalline micro/nanopores and microcracks, as summarized by the field emission scanning electron microscopy and energy dispersive spectroscopy analysis. Four differently sized pores develop: micropores account for approximately 20%, transition pores account for approximately 30%, and mesopores and macropores account for approximately 25% each. The pore throat development below 100 nm is greater than 50% according to the collation of experimental data from high-pressure mercury intrusion; therefore, micro/nanopores are the main storage space in the study area, and the gas logging shows good results. Micro/nanopores are also one of the main reservoir spaces of bedrock reservoirs in conjunction with the conventional reservoir space, and thus, micro/nanopores have important petroleum significance.

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