Search Results

Advanced search parameters have been applied.
open access

Cross Sections for X-Ray Photoelectron-Induced Desorption of Hydrogen Ions From Metal Surfaces

Description: We have measured the cross sections for x-ray photoelectron-induced desorption of hydrogen ions from beryllium, carbon, aluminum, tantalum, and gold surfaces. This report describes the results of the cross-section measurements, and discusses a time-of-flight technique that allows the determination of ionic-desorption cross sections as small as 10/sup -25/ cm/sup 2/ per photoelectron. 19 refs., 7 figs.
Date: September 20, 1985
Creator: Kinney, J. H.; Siekhaus, W. J. & Anderson, R. A.
Partner: UNT Libraries Government Documents Department
open access

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)
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

Existence of fcc TiCr/sub 1/ /sub 8/H/sub 5/ /sub 3/

Description: Originally an orthorhombic structure was assigned to the non-stoichiometric hydride TiCr/sub 1/ /sub 8/H/sub 3/ /sub 6/. Recent neutron and x-ray diffraction data indicated, however, that an alternate interpretation was possible, i.e. the solid consists of two hydride phases, an ..cap alpha..' Laves phase having a composition of TiCr/sub 1/ /sub 8/H/sub 2/ /sub 8/ and an fcc phase with a much higher hydrogen content. This proved to be the case and it has been determined that the high concentrat… more
Date: February 1, 1982
Creator: Johnson, J. R.; Reilly, J. J.; Reidinger, F.; Corliss, L. M. & Hastings, J. M.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

Sampling and analysis of trace-organic constituents in ambient and workplace air at coal-conversion facilities

Description: A review of the recent literature reveals that current sampling procedures involve the use of glass fiber filters for particulate-sorbed organics and sorbent resins such as Tenax GC and XAD-2 for vapor-phase organics. Ultra trace-organic analysis of air pollutants or particulates may require the collection of a large (1000 to 3000 m/sup 3/) sample by a high volume air sampler. Personal air sampling requires a smaller (approx. = 0.5 m/sup 3/) and a portable collection apparatus. Trapped organic … more
Date: July 1, 1980
Creator: Flotard, R D
Partner: UNT Libraries Government Documents Department
open access

Assessment and development of an advanced heat pump for recovery of volatile organic compounds

Description: This report documents Phase 1 of a project conducted by Mechanical Technology Incorporated (MTI) for the assessment and development of an advanced heat pump for recovery of VOC solvents from process gas streams. In Phase 1, MTI has evaluated solvent recovery applications within New York State (NYS), identified host sites willing to implement their application, and conducted a preliminary design of the equipment required. The design and applications were evaluated for technical and economic feas… more
Date: June 1, 1992
Partner: UNT Libraries Government Documents Department
open access

Multicomponent mass transport model: a model for simulating migration of radionuclides in ground water

Description: This report presents the results of the development of a one-dimensional radionuclide transport code, MMT2D (Multicomponent Mass Transport), for the AEGIS Program. Multicomponent Mass Transport is a numerical solution technique that uses the discrete-parcel-random-wald (DPRW) method to directly simulate the migration of radionuclides. MMT1D accounts for: convection;dispersion; sorption-desorption; first-order radioactive decay; and n-membered radioactive decay chains. Comparisons between MMT1D … more
Date: July 1, 1980
Creator: Washburn, J.F.; Kaszeta, F.E.; Simmons, C.S. & Cole, C.R.
Partner: UNT Libraries Government Documents Department
open access

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
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

Waste Isolation Safety Assessment Program. Task 4. Third Contractor Information Meeting. [Adsorption-desorption on geological media]

Description: The study subject of this meeting was the adsorption and desorption of radionuclides on geologic media under repository conditions. This volume contans eight papers. Separate abstracts were prepared for all eight papers. (DLC)
Date: June 1, 1980
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

Auger decay mechanism in photon-stimulated desorption of ions from surfaces

Description: Photon-stimulated desorption (PSD) of positive ions was studied with synchrotron radiation using an angle-integrating time-of-flight mass spectrometer. Ion yields as functions of photon energy near core levels were measured from condensed gases, alkali fluorides, and other alkali and alkaline earth halides. These results are compared to bulk photoabsorption measurements with emphasis on understanding fundamental desorption mechanisms. The applicability of the Auger decay mechanism, in which ion… more
Date: November 1, 1983
Creator: Parks, C.C.
Partner: UNT Libraries Government Documents Department
open access

Chemical Technology Division, Annual technical report, 1991

Description: Highlights of the Chemical Technology (CMT) Division's activities during 1991 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) technology for fluidized-bed combustion and coal-fired magnetohydrodynamics; (3) methods for treatment of hazardous and mixed hazardous/radioactive waste; (4) the reaction of nuclear waste glass and spent fuel under conditions expected for an uns… more
Date: March 1, 1992
Partner: UNT Libraries Government Documents Department
open access

Photodegradation effects in materials exposed to high flux solar and solar simulated radiation

Description: This report contains study results about photodegradation effects in materials exposed to high flux solar and solar simulated radiation. The studies show that high flux photoirradiation of materials can result in significant changes in the stability of materials. Photodesorption and photo-enhanced oxidation were determined to be the major mechanisms. These mechanisms were shown to affect, in extremely adverse ways, the expected thermal stability of solar relevant materials, especially stainless… more
Date: April 1, 1992
Creator: Ignatiev, A
Partner: UNT Libraries Government Documents Department
open access

CO + H/sub 2/ reaction over nitrogen-modified iron catalysts. Quarterly technical progress report, October 1, 1983-December 30, 1983. [Denitriding of iron nitrides in both hydrogen and helium]

Description: The synthesis of epsilon-Fe/sub 2.7/N is confirmed by Moessbauer spectroscopy. Carburization of epsilon-iron nitride for 2.5 hours in 3H/sub 2//CO at 523 K starts the formation of a bulk structure similar to that seen during ..gamma..'-iron nitride carburization. Reaction of ..gamma..'-Fe/sub 4/N in 3CO/H/sub 2/ synthesis gas at 523 K shows a better bulk stability than reaction in 3H/sub 2//CO. Kinetic analysis of the product distribution at the higher CO ratio confirms greater activity and sel… more
Date: February 1, 1984
Creator: Delgass, W.N.
Partner: UNT Libraries Government Documents Department
open access

Study of Electron and UV Photon Surface Interactions. Progress Report, March 1, 1977--February 28, 1978

Description: Considerable data on ESD from 304 stainless steel have been obtained. Cross sections as a function of bombarding electron energy, surface temperature, desorbing species, etc. are now available. Energy distributions of desorbing ions have also been tabulated. It is interesting to note that regardless of sample material and sample preparation H/sup +/ and F/sup +/ were always predominant ESD species. Electron induced dissociation of metal oxides, noted during AES measurements, has been studied fo… more
Date: November 1, 1977
Creator: Lichtman, D.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
open access

Investigation of methods for the selective removal and characterization of transition metals associated with solids in the marine environment

Description: The operation of an OTEC plant will result in the mixing of large volumes of seawater from different depths within the ocean. Because suspended particulate material is intimately involved in marine food webs and transition metals, such as copper, can have toxic effects, it is important to develop a sound methodology for characterizing and quantifying transition metal behavior associated with the solid material. The characterization of solid-phase-associated transition metals in the marine envir… more
Date: February 1, 1981
Creator: Van Valin, R. & Morse, J. W.
Partner: UNT Libraries Government Documents Department
open access

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.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen