Nanogate - A Nanosecond Gated Image Intensifier with High Gain and High Resolution

Understanding of catalytic processes requires detailed knowledge of the catalyst. As heterogeneous catalysis is a surface phenomena the understanding of the atomic surface structure of both the active material and the support material is of utmost importance. This work is a high resolution electron microscopy (HREM) study of different phases found in a used automobile catalytic converter.The high resolution micrographs were obtained with a JEM-4000EX working with a structural resolution better than 0.17 nm and equipped with a Gatan 622 TV-camera with an image intensifier. Some work (e.g. EDS-analysis and diffraction) was done with a JEM-2000FX equipped with a Link AN10000 EDX spectrometer. The catalytic converter in this study has been used under normal driving conditions for several years and has also been poisoned by using leaded fuel. To prepare the sample, parts of the monolith were crushed, dispersed in methanol and a drop of the dispersion was placed on the holey carbon grid.

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A Structural Model for a Quasi-Crystalline Material Derived from TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178999 ◽

1990 ◽

Vol 48 (1) ◽

pp. 48-49

Author(s):

Jan-Olov Bovin ◽

Osamu Terasaki ◽

Jan-Olle Malm ◽

Sven Lidin ◽

Sten Andersson

Keyword(s):

High Resolution ◽

Electron Diffraction ◽

Structural Model ◽

Image Intensifier ◽

Crystalline Materials ◽

Icosahedral Phases ◽

Transmission Electron ◽

Electron Microscopes ◽

Diffraction Patterns ◽

Quasi Crystals

High resolution transmission electron microscopy (HRTEM) is playing an important role in identifying the new icosahedral phases. The selected area diffraction patterns of quasi crystals, recorded with an aperture of the radius of many thousands of Ångströms, consist of dense arrays of well defined sharp spots with five fold dilatation symmetry which makes the interpretation of the diffraction process and the resulting images different from those invoked for usual crystals. The atomic structure of the quasi crystals is not established even if several models are proposed. The correct structure model must of course explain the electron diffraction patterns with 5-, 3- and 2-fold symmetry for the phases but it is also important that the HRTEM images of the alloys match the computer simulated images from the model. We have studied quasi crystals of the alloy Al65Cu20Fe15. The electron microscopes used to obtain high resolution electro micrographs and electron diffraction patterns (EDP) were a (S)TEM JEM-2000FX equipped with EDS and PEELS showing a structural resolution of 2.7 Å and a IVEM JEM-4000EX with a UHP40 high resolution pole piece operated at 400 kV and with a structural resolution of 1.6 Å. This microscope is used with a Gatan 622 TV system with an image intensifier, coupled to a YAG screen. It was found that the crystals of the quasi crystalline materials here investigated were more sensitive to beam damage using 400 kV as electron accelerating voltage than when using 200 kV. Low dose techniques were therefore applied to avoid damage of the structure.

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Line of Sight Analysis

10.5194/epsc2021-150 ◽

2021 ◽

Author(s):

Emily Law ◽

Natalie Gallegos ◽

Shan Malhotra

Keyword(s):

High Resolution ◽

Solar System ◽

High Gain ◽

Line Of Sight ◽

Time Intervals ◽

Ground Station ◽

Points Of Interest ◽

Digital Elevation ◽

Initial Release ◽

Elevation Model

The Line of Sight (LoS) is one of the latest tools to join the analytics suite of tools for the Solar System Treks (https://trek.nasa.gov) portals.&#160; The LoS tool provides a way to compute visibility between the entities in our solar system. More concretely, this utility searches for windows of communication or a &#8220;line of sight&#8221; between any two entities. Entities include orbiters, rovers, planetary bodies, ground stations, and other topographical locations. In addition to establishing communications between the two entities, the tool also takes into account local terrains of the entities in question. The software seeks to answer questions about establishing communications between a rover and an orbiter, or an orbiter to a ground station. In mission planning, LoS can be used to determine possible traverses for a rover that must maintain communications with a lander, or find time intervals of communication to an orbiter when a rover or lander are near an obstructing surface feature such as a crater rim or mound. Computations can be even more granular and lines of sight can be computed between mission instruments, thus allowing to ask questions such as &#8220;Is the High Gain Antenna on a rover visible from an orbiter?&#8221; The initial release of the software focuses on the lunar surface and the LRO spacecraft. Users can ask whether a topographical location on the moon is visible from the orbiter or a discrete set of ground stations on Earth. The tool uses NAIF SPICE and various mission kernels for computing planetary geometries. LoS also uses high resolution Digital Elevation Model (DEM) to model the terrain surrounding the points of interest. In-house software is used to convert high resolution DEMs into a format compatible with the tool. Users can provide their own DEMs to model the terrain on different topographical locations to use for their own computations.

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