19,239 research outputs found
Detection of nanoparticles by means of reflection electron energy loss spectroscopy depth profiling
The various studies of nanoparticles are of great importance because of the wide application of nanotechnology. The shape and structure of the nanoparticles can be determined by transmission electron microscopy (TEM) and their chemistry by electron energy loss spectroscopy. TEM sample preparation is an expensive and difficult procedure, however. Surface sensitive, analytical techniques, such as Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) are well applicable to detect the atoms that make up the nanoparticles, but cannot determine whether particle formation occurred. On the other hand, reflection electron energy loss spectroscopy (REELS) probes the electronic structures of atoms, which are strongly different for the atoms being in solution or in precipitated form. If the particle size is in the nm range, plasmon resonance can be excited in it, which appears as a loss feature in REELS spectrum. Thus, by measuring AES (XPS) spectra parallel with those of REELS, besides the atomic concentrations the presence of the nanoparticles can also be identified. As an example, the appearance of nanoparticles during ion beam induced mixing of C/Si layer will be shown
High temperature electronic requirements in aeropropulsion systems
The needs for high temperature electronic and electro-optic devices as they would be used on aircraft engines in either research and development applications, or operational applications are discussed. The conclusion reached is that the temperature at which the devices must be able to function is in the neighborhood of 500 to 600 C either for R&D or for operational applications. In R&D applications the devices must function in this temperature range when in the engine but only for a moderate period of time. On an operational engine, the reliability requirements dictate that the devices be able to be burned-in at temperatures significantly higher than those at which they will function on the engine. The major point made is that semiconductor technology must be pushed well beyond the level at which silicon will be able to function
Broadway Rag
Man and woman standing away from, but looking towards the fronthttps://scholarsjunction.msstate.edu/cht-sheet-music/13683/thumbnail.jp
The Troubadour : Intermezzo Two Step
https://digitalcommons.library.umaine.edu/mmb-ps/1040/thumbnail.jp
Sunbeam
Illustration of Native American woman sitting on ground holding tomahawk; Teepees, man rowing canoe, river, and trees in backgroundhttps://scholarsjunction.msstate.edu/cht-sheet-music/7657/thumbnail.jp
Hesitation Con Amore : Valse
https://digitalcommons.library.umaine.edu/mmb-ps/2721/thumbnail.jp
Silvery Moonlight
Man and woman riding a canoehttps://scholarsjunction.msstate.edu/cht-sheet-music/13882/thumbnail.jp
Regimental Daughters : March and Two Step
https://digitalcommons.library.umaine.edu/mmb-ps/2362/thumbnail.jp
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