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Dependence of secondary ion emission from organic material on the energy loss of the impacting heavy ion

Description: Samples of the amino acid valine were irradiated by 2.5 MeV-Ar, 0.8 MeV-Kr and 1.0 MeV Xe beams from the Argonne Dynamitron accelerator in order to study the energy distributions of ejected secondary ions. For Kr and Xe the nuclear stopping power exceeded the electronic stopping power by a factor 2 or 3, respectively, but the functional shape of the energy distributions and the mean ejection energies (0.9--1.4 eV) indicated that the molecular ions (M{plus minus}H){sup {plus minus}} are desorbed… more
Date: January 1, 1991
Creator: Hunt, J.E. (Argonne National Lab., IL (United States)) & Wien, K. (Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik)
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Partner: UNT Libraries Government Documents Department
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Structure of NH/sub 3/ on Ni(111)

Description: In a recent study of the adsorption of NH/sub 3/ on NI(111) at T approx. 190 K using angle resolved UPS, it was concluded that NH/sub 3/ is molecularly adsorbed, and is bonded to the surface via the N atom with the H atoms oriented away from the surface. To study the bonding configuration using a direct and independent technique, we have examined NH/sub 3/ on Ni(111) using the electron stimulated desorption ion angular distribution (ESDIAD) method, coupled with temperature programmed desorption… more
Date: January 1, 1980
Creator: Madey, T. E.; Houston, J. E.; Seabury, C. W. & Rhodin, T. N.
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Partner: UNT Libraries Government Documents Department
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Reactivity of Young Chars via Energetic Distribution Measurements

Description: In this report, we present some preliminary work performed on the effect of CO{sub 2} partial pressure on temperature programmed desorption spectra from CO{sub 2}-oxidized chars. The following was accomplished during the reporting period: Temperature programmed desorption (TPD) experiments were conducted on oxidized resin and Wyodak coal char samples gasified under varying different CO{sub 2} partial pressures. The following observations were made: CO{sub 2} partial pressure can be an important… more
Date: January 1, 1991
Creator: Calo, J. M.; Zhang, L. H.; Rachel, W. G. & Lilly, W. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Tritium permeability of structural materials and surface effects on permeation rates

Description: Tritium management in any system always will include containment such that tritium release rates will be less than established limits and also will be as low as practical. The well known properties of hydrogen to permeate through most materials make the complete containment of tritium an impossible task. However, tritium release rates from a given system can be minimized by two primary efforts. First is the selection of a compatible containment material which frequently also will be the structu… more
Date: January 1, 1980
Creator: Bell, J T; Redman, J D & Bittner, H F
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Partner: UNT Libraries Government Documents Department
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Activated recombinative desorption: a potential component in mechanisms of spacecraft glow

Description: The concept of activated recombination of atomic species on surfaces is capable of explaining the production of vibrationally and translationally excited desorbed molecular species. Equilibrium statistical mechanics predicts that the molecular quantum state distributions of desorbing molecules is a function of only the surface temperature when the adsorption probability is unity and independent of initial collision conditions. In most cases though the adsorption probability is dependent upon in… more
Date: January 1, 1985
Creator: Cross, J.B.
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Partner: UNT Libraries Government Documents Department
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Kinetic and equilibrium measurements of coal drying

Description: The retention, attachment, and release of water (sorption, adsorption, and desorption) in Fruitland subbituminous coal are shown to be very complex phenomena. The vapor pressure and thermodynamic activity of water in the coal at about 315 K vary sharply with composition. Removal of 60% of the water initially present reduces the vapor pressure by about 60%. The total moisture content of saturated coal also varies with temperature. A 10 K rise in temperature reduces the sorbed water by about 8%. … more
Date: January 1, 1980
Creator: Heller, A. & Elliott, G.R.B.
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Partner: UNT Libraries Government Documents Department
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Temperature programmed desorption from LiAlO sub 2 treated with H sub 2

Description: Temperature programmed desorption (TPD) measurements have been made of H{sub 2}O and H{sub 2} desorption from LiAlO{sup 2} treated at 923 K with He-H{sub 2} mixtures containing 990, 495, and 227 vppm H{sub 2}. Desorptions were into sweep gases of pure He and into He-H{sub 2} mixtures. The H{sub 2}O and H{sub 2} desorption peaks were shown to be the sums of first order subpeaks which had reproducible desorption activation energy and pre-exponential terms. For H{sub 2}O desorption, the activation… more
Date: January 1, 1991
Creator: Fischer, A.K.
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Partner: UNT Libraries Government Documents Department
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Field studies and modeling of chemical processes in the unsaturated zone

Description: Technical assistance is being provided to Nuclear Materials Safety and Safeguards of the Nuclear Regulatory Commission to evaluate the validity of several guidelines listed in 10 CFR Part 61 for the future burial of low-level radioactive waste. Those guidelines include the requirement that the burial site shall be capable of being modeled. Both laboratory- and field-scale studies are being conducted under unsaturated moisture conditions and under steady-state and unsteady-state flow conditions.… more
Date: January 1, 1985
Creator: Polzer, W.L. & Fuentes, H.R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comparison of photodesorption yields from aluminum stainless and Cu-plated beam tubes

Description: Photon Stimulated Desorption (PSD) from the walls of beam ducts constitutes the most serious gas load in storage rings and therefore exerts a great influence on both beam quality and lifetime. With the exception of the SSC which plans to use a Cu-plated beam tube, all existing and proposed machines use either aluminum or stainless steel beam tubes. In order to develop techniques for producing surfaces with the lowest PSD, we have studied the above materials using a dedicated beam line at the Na… more
Date: January 1, 1989
Creator: Halama, H.J. & Foerster, C.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Thermal desorption spectroscopy (TDS) of hydrogen from niobium

Description: Thermal desorption spectroscopy is often used to determine the activation energy of desorption of an adsorbate on a substrate as well as the order of the kinetics. In the case of flash desorption of an adsorbate from a surface obeying second order kinetics, a plot of Log(theta/sub o/T/sub p//sup 2/) vs 1/T/sub p/ (where theta/sub o/ is the initial surface coverage and T/sub P/ is the temperature of the maximum desorption rate, i.e., the desorption temperature) will yield a straight line, the sl… more
Date: January 1, 1982
Creator: Ghosh, V.J.; Pick, M.A.; Welch, D.O. & Dienes, G.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The search for low photodesorption coatings

Description: Low photo desorption (PSD) from surfaces of vacuum chambers increases the beam lifetime and reduces the cost of the pumping system of any storage ring. In compact rings where all radiated power ({approximately}10 kW) is incident on a few meters only, low PSD and good thermal conductivity of photon absorbers are of particular importance. An experimental chamber in which one meter long bars can be exposed to white photon beam with 500 eV critical energy has been built and installed on the U10B be… more
Date: January 1, 1990
Creator: Foerster, C.L. & Korn, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Tube effects and the kinetics of desorption of H sub 2 O/H sub 2 from LiAlO sub 2 by temperature programmed desorption measurements

Description: Temperature programmed desorption (TPD) measurements are in progress to provide data describing the kinetics of desorption of H{sub 2}O(g) and H{sub 2}(g) from ceramic tritium breeders. Preliminary blank experiments indicated that the steel can be a reactive participant with H{sub 2}O being consumed and H{sub 2} being evolved. There is also evidence of some dissolution of H{sub 2} in the steel. However, it is possible to stabilize the tube in the absence of added H{sub 2} so that useful measure… more
Date: January 1, 1989
Creator: Fischer, A. K. & Johnson, C. E.
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Partner: UNT Libraries Government Documents Department
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Trapping, detrapping, and replacement of keV hydrogen implanted into graphite

Description: Trapping and detrapping of low energy hydrogen isotopes in graphite is relevant to the collection of fuel particles in graphite probes for diagnostics of particle fluxes and energies in the plasma boundary layer, and to the recycling of fuel particles. The measurement of saturation concentrations by ..cap alpha.. profiling of D may be influenced by detrapping of deuterium by the analyzing /sup 3/He-beam.
Date: January 1, 1980
Creator: Roth, J.; Scherzer, B. M.U.; Blewer, R. S.; Brice, D. K.; Picraux, S. T. & Wampler, W. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Structures of adsorbed CO on atomically smooth and on stepped sngle crystal surfaces

Description: The structures of molecular CO adsorbed on atomically smooth surfaces and on surfaces containing monatomic steps have been studied using the electron stimulated desorption ion angular distribution (ESDIAD) method. For CO adsorbed on the close packed Ru(001) and W(110) surfaces, the dominant bonding mode is via the carbon atom, with the CO molecular axis perpendicular to the plane of the surface. For CO on atomicaly rough Pd(210), and for CO adsorbed at step sites on four different surfaces vici… more
Date: January 1, 1980
Creator: Madey, T.E. & Houston, J.E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Studies of surface adsorption on LiAlO/sub 2/

Description: Computational and experimental approaches are being taken to understanding surface adsorption/desorption effects on tritium inventory and release. The computational survey integrates a thermodynamic treatment of surface adsorption and bulk phase effects such as solubility and gas phase composition. The system T/sub 2/O:T/sub 2/:LiAlO/sub 2/ was examined. The calculations indicate that surface adsorption can be expected to contribute most to tritium inventory under the conditions of lower temper… more
Date: January 1, 1986
Creator: Fischer, A. K.; McDaniel, J. A. & Johnson, C. E.
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Partner: UNT Libraries Government Documents Department
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Reactivity of young chars via energetic distribution measurements

Description: The temperature programmed desorption (TPD) has become a standard technique for investigating the physico-chemical state of adsorbed species on surfaces. In this reporting period, a new TPD-MS/TGA (mass spectrometry/thermal gravimetric analysis) system has been designed, and all the necessary components have been acquired. This new system is built around a new Cahn D-200 digital recording microbalance, which was recently purchased for this purpose. The TPD reactor essentially becomes the hangdo… more
Date: January 1, 1991
Creator: Calo, J.M.; Zhang, L.H. & Lilly, W.D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Desorption of large organic molecules by laser-induced plasmon excitation

Description: Ejection of large organic molecules from surfaces by laser-induced electronic-excited desorption has attracted considerable interest in recent years. In addition to the importance of this effect for fundamental investigations of the ejection process, this desorption technique has been applied to the study of large, fragile molecules by mass spectrometry. In this paper, we present a new method to induce electronic excitation on the metal surface for the desorption of large organic molecules. 3 r… more
Date: January 1, 1991
Creator: Lee, I.; Callcott, T.A. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Physics and Astronomy) & Arakawa, E.T. (Oak Ridge National Lab., TN (USA))
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Partner: UNT Libraries Government Documents Department
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Photon stimulated desorption of neutral species from aluminum

Description: Photon Simulated Desorption of neutral species (PSD) is the major dynamic gas load in electron synchrotron light source. In the National Synchrotron Light Source, PSD presented initial machine commissioning difficulty. Sensitivity to surface contamination on PSD had been experienced during an incident of Fomblin Oil contamination. U10B-Photon Stimulated Desorption Experimental Station is constructed to investigate: (1) the degree of the contribution to the photon stimulated desorption (PSD) fro… more
Date: January 1, 1991
Creator: Chou, T.S.
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Partner: UNT Libraries Government Documents Department
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Chemical cleaning of aluminum alloy surfaces for use as vacuum materials in synchrotron light sources

Description: Photon and electron desorption from the vacuum chamber walls of electron storage rings such as the proposed Advanced Photon Source (APS), are sometimes responsible for the production of large gas loads during operation even in systems with very good static vacuum. The gas released by beam-induced desorption results in scattering of the beam electrons, and a consequent reduction in the beam lifetime. In extreme cases, the beam-induced outgassing may cause so much scattering that it is not possib… more
Date: January 1, 1989
Creator: Kaufherr, N.; Krauss, A.; Gruen, D.M.; Nielsen, R. (Illinois Univ., Urbana, IL (USA). Materials Research Lab. & Argonne National Lab., IL (USA))
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Partner: UNT Libraries Government Documents Department
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Hydrogen pumping and release by graphite under high flux plasma bombardment

Description: Inert gas (helium or argon) plasma bombardment has been found to increase the surface gas adsorptivity of isotropic graphite (POCO-graphite), which can then getter residual gases in a high vacuum system. The inert gas plasma bombardment was carried out at a flux approx. = 1 x 10/sup 18/ ions s/sup -1/ cm/sup -2/ to a fluence of the order of 10/sup 21/ ions/cm/sup 2/ and at temperatures around 800/sup 0/C. The gettering capability of graphite can be easily recovered by repeating inert gas plasma… more
Date: January 1, 1988
Creator: Hirooka, Y.; Leung, W. K.; Conn, R. W.; Goebel, D. M.; LaBombard, B.; Nygren, R. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Thermodynamic and kinetic aspects of surface acidity

Description: Our research in the general area of acid catalysis involves the characterization of solid acidity and the corresponding assessment of catalytic performance of acidic materials. Acid characterization studies are required to provide essential information about the type of acid site (i.e., Lewis versus Bronsted), the strength of the sites, and the mobility of molecules adsorbed on the acid sites. An accurate measure of acid strength is given by the heat of adsorption of a basic probe molecule on t… more
Date: January 1, 1992
Creator: Dumesic, J.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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