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In-situ characterization of common impurities in uranium metal by spark spectrochemistry

Description: A rapid spectrochemical method, involving the application of a condensed spark to finished or semifinished uranium metal surfaces, was developed to analyze large numbers of parts (50 or more in a single day) for up to nine specification impurity elements. No sampling or preparation is required, and the on-site analysis is carried out by transporting the spectrograph and source to the production area. The procedure is used for process control and is supplemental to the more refined pyro carrier spectrochemical analysis used for product certification. Elements determined by the large quartz prism spectrograph include: copper, iron, molybdenum, nickel, niobium, titanium, silicon, and zirconium. Carbon is determined by a very slight change in procedure. (auth)
Date: March 29, 1974
Creator: King, H.G.
Partner: UNT Libraries Government Documents Department

Hidden quasars in ultraluminous infared galaxies

Description: Abstract. Many ultraluminous infrared galaxies (ULIRGS) are pow- ered by quasars hidden in the center, but many are also powered by starbursts. A simply diagnostic diagram is proposed that can iden- tify obscured quasars in ULIRGs by their high-ionization emission lines ([0 III]X5007/HP ,? 5), and �warm� IR color (&/f6s 2 0.25).
Date: August 27, 1998
Creator: Brotherton, M. S.; Stanford, S. A.; Tran, H. & van Breugel, W.
Partner: UNT Libraries Government Documents Department

Effect of particle size on the carrier-distillation analysis of PuO$sub 2$

Description: A study was made to determine the effect of particle size on the carrier- distillation analysis of PuO/sub 2/ and to explain how to avoid the difficulties caused by large PuO/sub 2/ particles. The relative intensity of five elements was determined for three particle sizes and it was shown that it increases as the particle size becomes smaller. Further the line intensity of the added internal standard Co also increased with decreasing particle size. Accurate spectrochemical results were obtained when the PuO/sub 2/ particle size was reduced to 45 mu m or less. (JSR)
Date: January 1, 1974
Creator: Martell, C.J.
Partner: UNT Libraries Government Documents Department

Electronic structure of cobalt nanocrystals suspended inliquid

Description: The electronic structure of cobalt nanocrystals suspended in liquid as a function of size has been investigated using in-situ x-ray absorption and emission spectroscopy. A sharp absorption peak associated with the ligand molecules is found that increases in intensity upon reducing the nanocrystal size. X-ray Raman features due to d-d and to charge-transfer excitations of ligand molecules are identified. The study reveals the local symmetry of the surface of {var_epsilon}-Co phase nanocrystals, which originates from a dynamic interaction between Co nanocrystals and surfactant + solvent molecules.
Date: July 16, 2007
Creator: Liu, Hongjian; Guo, Jinghua; Yin, Yadong; Augustsson, Andreas; Dong, Chungli; Nordgren, Joseph et al.
Partner: UNT Libraries Government Documents Department

Effect of Mn Substitution for Multiferroic BiFeO3 Probed by High-Resolution Soft-X-Ray Spectroscopy

Description: The electronic structures of BiFeO{sub 3} (BF) and Mn-doped BiFeO{sub 3} (BF(Mn)) have been studied by X-ray absorption spectroscopy (XAS) and soft-X-ray emission spectroscopy (SXES). The BF and BF(Mn) have the mixed valence state of Fe{sup 2+} and Fe{sup 3+}. The valence band is mainly composed of O 2p state hybridized with the majority-spin t{sub 2g} and e{sub g} orbitals of Fe 3d state. The conduction band is composed of the minority-spin t{sub 2g} and e{sub g} orbitals of Fe 3d. The band gaps of BF and BF(Mn) are estimated to be 1.3 eV and 2.7 eV, respectively. The increase of band gap with Mn substitution contributes to the change of bandwidth of valence band.
Date: July 11, 2008
Creator: Higuchi, Tohru; Higuchi, T.; Hattori, T.; Sakamoto, W.; Itoh, N.; Shimura, T. et al.
Partner: UNT Libraries Government Documents Department

Electronic Structure of the ID Conductor K0.3MoO3 studied using resonant inelastic x-ray scattering and soft x-ray emission spectroscopy

Description: The electronic structure of the quasi-one dimensional conductor K{sub 0.3}MoO{sub 3} has been measured using high resolution resonant inelastic x-ray scattering and x-ray absorption spectroscopy. The data is compared to that from the related two dimensional insulator {alpha}-MoO{sub 3}. Scattering features are observed from both oxides that are explained in terms of the band momentum selectivity of the scattering process, allowing a comparison of the scattering data to recent band structure calculations.
Date: September 24, 2008
Creator: Learmonth, T.; Glans, P.-A.; McGuinness, C.; Plucinski, L.; Zhang, Y.; Guo, J.-H. et al.
Partner: UNT Libraries Government Documents Department

Mg-induced increase of bandgap in Zn1-xMgxO nanorods revealed by x-ray absorption and emission spectroscopy

Description: X-ray absorption near-edge structure (XANES) and x-ray emission spectroscopy (XES) measurements were used to investigate the effect of Mg doping in ZnO nanorods. The intensities of the features in the O K-edge XANES spectra of Zn{sub 1-x}Mg{sub x}O nanorods are lower than those of pure ZnO nanorods, suggesting that Mg doping increases the negative effective charge of O ions. XES and XANES spectra of O 2p states indicate that Mg doping raises (lowers) the conduction-band-minimum (valence-band-maximum) and increases the bandgap. The bandgap is found to increase linearly with the Mg content, as revealed by photoluminescence and combined XANES and XES measurements.
Date: July 10, 2008
Creator: Pong, Way-Faung; Chiou, J. W.; Tsai, H. M.; Pao, C. W.; Chien, F. Z.; Pong, W. F. et al.
Partner: UNT Libraries Government Documents Department

A preliminary report on the photoionization efficiency spectrum, ionization energy and heat of formation of Br{sub 2}O; and the appearance energy of BrO{sup +} (Br{sub 2}O)

Description: We report experimental results for the photoionization efficiency (PIE) spectrum of Br{sub 2}O along with the ionization energy (derived form the ionization threshold) and the appearance energy (AE) of BrO{sup +} (Br{sub 2}O). A value for the heat of formation of Br{sub 2}O is derived form the AE result. Experiments were performed by employing a discharge flow-photoionization mass spectrometer (DF-PIMS) apparatus coupled to beamline U-11 at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory.
Date: August 1, 1995
Creator: Thorn, R. P., Jr.; Monks, P. S.; Stief, L. J.; Kuo, S. C.; Zhang, Z. & Klemm, R. B.
Partner: UNT Libraries Government Documents Department

Excitations and Optical Properties of Phenylene Based Polymers

Description: A complex picture of phenylene-based polymers is developed which unifies features of band and molecular exciton models. It incorporates major experimental finding in direct, and photoinduced optical absorption, stimulated photoemission and photoconductivity. The authors give new assignments for the most disputed features and identify new ones as edge states. The authors confirm a low binding energy for the principle emitting exciton and show that it dominates also in the fundamental absorption. Contradictions in the current modeling state-of-art are displayed and discussed.
Date: July 1, 1998
Creator: Kirova, N.; Brazovskii, S.; Bishop, A.R.; McBranch, D. & Klimov, V.
Partner: UNT Libraries Government Documents Department

The Absence of Plasma in"Spark Plasma Sintering"

Description: Spark plasma sintering (SPS) is a remarkable method for synthesizing and consolidating a large variety of both novel and traditional materials. The process typically uses moderate uni-axial pressures (<100 MPa) in conjunction with a pulsing on-off DC current during operation. There are a number of mechanisms proposed to account for the enhanced sintering abilities of the SPS process. Of these mechanisms, the one most commonly put forth and the one that draws the most controversy involves the presence of momentary plasma generated between particles. This study employees three separate experimental methods in an attempt to determine the presence or absence of plasma during SPS. The methods employed include: in-situ atomic emission spectroscopy, direct visual observation and ultra-fast in-situ voltage measurements. It was found using these experimental techniques that no plasma is present during the SPS process. This result was confirmed using several different powders across a wide spectrum of SPS conditions.
Date: April 10, 2008
Creator: Hulbert, Dustin M.; Anders, Andre; Dudina, Dina V.; Andersson, Joakim; Jiang, Dongtao; Unuvar, Cosan et al.
Partner: UNT Libraries Government Documents Department

Soft X-ray synchrotron radiation investigations of actinidematerials systems utilizing X-ray emission spectroscopy and resonantinelastic X-ray scattering

Description: Synchrotron radiation (SR) methods have been utilized with increasing frequency over the past several years to study topics in actinide science, ranging from those of a fundamental nature to those that address a specifically-targeted technical need. In particular, the emergence of microspectroscopic and fluorescence-based techniques have permitted investigations of actinide materials at sources of soft x-ray SR. Spectroscopic techniques with fluorescence-based detection are useful for actinide investigations since they are sensitive to small amounts of material and the information sampling depth may be varied. These characteristics also serve to simplify both sample preparation and safety considerations. Examples of investigations using these fluorescence techniques will be described along with their results, as well as the prospects for future investigations utilizing these methodologies.
Date: January 3, 2004
Creator: Shuh, D.K.; Butorin, S.M.; Guo, J.-H. & Nordgren, J.
Partner: UNT Libraries Government Documents Department

Comment on ?Spin crossover in (Mg,Fe)O: A M?ssbauer effect study with an alternative interpretation of x-ray emission spectroscopy data?

Description: Electronic spin-pairing transition of iron in magnesiow{umlt u}stite-(Mg,Fe)O has been recently studied with X-ray emission and M{umlt o}ssbauer spectroscopies under high pressures. While these studies reported a high-spin to low-spin transition of iron to occur at pressures above approximately 50 GPa, the width of the observed transition varies significantly. In particular, Kantor et al. reported that the transition in (Mg0.8,Fe0.2)O occurs over a pressure range of approximately 50 GPa in high-pressure M{umlt o}ssbauer measurements. To account for the discrepancy in the transition pressure, Kantor et al. reanalyzed the X-ray emission spectra by Lin et al. using a simple spectral decomposition method and claimed that X-ray emission measurements are also consistent with a spin crossover of iron at high pressures. Here we show that the proposed fitting method is inadequate to describe the X-ray emission spectrum of the low-spin FeS2 and would give an erroneous satellite peak (K{sub beta}') intensity, leading to an artificial high-spin component and, consequently, to invalid conclusions regarding the width of the pressure-induced transition in magnesiow{umlt u}stite. Furthermore, we compare Kantor's M{umlt o}ssbauer data with other recent high-pressure M{umlt o}ssbauer studies and show that the width of the transition can be simply explained by different experimental conditions (sample thickness, diameter, and hydrostaticity).
Date: May 23, 2006
Creator: Lin, J.; Struzhkin, V. V. & Garriliuk, A.
Partner: UNT Libraries Government Documents Department

Kondo-like 4f delocalization in Gd at high pressure

Description: We present resonant inelastic x-ray scattering (RIXS) and x-ray emission spectroscopy (XES) results which suggest Kondo-like aspects in the delocalization of 4f electrons in Gd metal to 113 GPa. Analysis of the RIXS data reveal a prolonged and continuous process throughout the entire pressure range, so that the volume collapse transition at 59 GPa is only part of the delocalization phenomenon. Moreover, the L{sub {gamma}1} XES spectra indicate no apparent change in the bare 4f moment across the collapse, suggesting that Kondo screening is responsible for the expected Pauli-like behavior in magnetic susceptibility.
Date: November 28, 2005
Creator: Maddox, B R; Lazicki, A; Yoo, C S; Iota, V; Chen, M; McMahan, A K et al.
Partner: UNT Libraries Government Documents Department

Electronic structure of multiferroic BiFeO3 by resonant soft-x-ray emission spectroscopy

Description: The electronic structure of multiferroic BiFeO{sub 3} has been studied using soft-X-ray emission spectroscopy. The fluorescence spectra exhibit that the valence band is mainly composed of O 2p state hybridized with Fe 3d state. The band gap corresponding to the energy separation between the top of the O 2p valence band and the bottom of the Fe 3d conduction band is 1.3 eV. The soft-X-ray Raman scattering reflects the features due to charge transfer transition from O 2p valence band to Fe 3d conduction band. These findings are similar to the result of electronic structure calculation by density functional theory within the local spin-density approximation that included the effect of Coulomb repulsion between localized d states.
Date: July 11, 2008
Creator: Higuchi, Tohru; Higuchi, T.; Liu, Y.-S.; Yao, P.; Glans, P.-A.; Guo, Jinghua et al.
Partner: UNT Libraries Government Documents Department

Electronic Spin Crossover of Iron in Ferroperclase in Earth?s Lower Mantle

Description: Pressure-induced electronic spin-pairing transitions of iron and associated effects on the physical properties have been reported to occur in the lower-mantle ferropericlase, silicate perosvkite, and perhaps in post silicate perovskite at high pressures and room temperature. These recent results are motivating geophysicists and geodynamicists to reevaluate the implications of spin transitions on the seismic heterogeneity, composition, as well as the stability of the thermal upwellings of the Earth's lower mantle. Here we have measured the spin states of iron in ferropericlase and its crystal structure up to 95 GPa and 2000 K using a newly constructed X-ray emission spectroscopy and diffraction with the laser-heated diamond cell. Our results show that an isosymmetric spin crossover occurs over a pressure-temperature range extending from the upper part to the lower part of the lower mantle, and low-spin ferropericlase likely exists in the lowermost mantle. Although continuous changes in physical and chemical properties are expected to occur across the spin crossover, the spin crossover results in peculiar behavior in the thermal compression and sound velocities. Therefore, knowledge of the fraction of the spin states in the lower-mantle phases is thus essential to correctly evaluate the composition, geophysics, and dynamics of the Earth's lower mantle.
Date: January 25, 2007
Creator: Lin, J F; Vanko, G; Jacobsen, S D; Iota, V; Struzhkin, V V; Prakapenka, V B et al.
Partner: UNT Libraries Government Documents Department


Description: Beryllium has been used widely in specific areas of nuclear technology. Frequent monitoring of air and possible contaminated surfaces in U.S Department of Energy (DOE) facilities is required to identify potential health risks and to protect DOE workers from beryllium-contaminated dust. A new method has been developed to rapidly remove spectral interferences prior to beryllium (Be) measurement by inductively-coupled plasma atomic emission spectrometry (ICP-AES). The ion exchange separation removes uranium (U), thorium (Th), niobium (Nb), vanadium (V), molybdenum (Mo), zirconium (Zr), tungsten (W), iron (Fe), chromium (Cr), cerium (Ce), erbium (Er) and titanium (Ti). A stacked column consisting of Diphonix Resin{reg_sign} and TEVA Resin{reg_sign} reduces the levels of the spectral interferences so that low level Be measurements can be performed accurately. If necessary, an additional anion exchange separation can be used for further removal of interferences, particularly chromium. The method has been tested using spiked filters, spiked wipe samples and certified reference material standards with high levels of interferences added. The method provides very efficient removal of spectral interferences with very good accuracy and precision for beryllium on filters or wipes. A vacuum box system is employed to reduce analytical time and reduce labor costs.
Date: January 14, 2008
Creator: Maxwell, S; Matthew Nelson, M; Linda Youmans, L & Maureen Bernard, M
Partner: UNT Libraries Government Documents Department

Laser sampling system for an inductively-coupled atomic emission spectrometer. Final report

Description: A laser sampling system was attached to a Perkin Elmer Optima 3000 inductively-coupled plasma, atomic emission spectrometer that was already installed and operating in the Chemistry and Geochemistry Department at the Colorado School of Mines. The use of the spectrometer has been highly successful. Graduate students and faculty from at least four different departments across the CSM campus have used the instrument. The final report to NSF is appended to this final report. Appendices are included which summarize several projects utilizing this instrument: acquisition of an inductively-coupled plasma atomic emission spectrometer for the geochemistry program; hydrogen damage susceptibility assessment for high strength steel weldments through advanced hydrogen content analysis, 1996 and 1997 annual reports; and methods for determination of hydrogen distribution in high strength steel welds.
Date: February 15, 1998
Partner: UNT Libraries Government Documents Department

Direct Drive Cylindrical Implosions on the Omega Laser at the Laboratory for Laser Energetics of the University of Rochester

Description: The primary goals of this report are to (1) understand experimental radiography better (radiograph known static targets); and (2) to better understand the sources and effects of short wavelength perturbations on the long wavelength RT growth. Some secondary goals are to initiate Richtmyer-Meshkov mix targets; test beryllium cylinder implosions (if available); and observe emission spectroscopy from chlorinated foam to study implosions. To achieve these goals the authors: (1) shot mix targets with late backlighter and confirmed set up of radiography, begin static targets; (2) did a sequence of unperturbed and perturbed targets of different smoothness and thickness, fill in static, beryllium, and chlorinated foam targets; and (3) repeated step number 2 at a different backlighter time.
Date: May 10, 1999
Creator: Barnes, C.W.
Partner: UNT Libraries Government Documents Department

Automated plasma control with optical emission spectroscopy

Description: Plasma etching and desmear processes for printed wiring board (PWB) manufacture are difficult to predict and control. Non-uniformity of most plasma processes and sensitivity to environmental changes make it difficult to maintain process stability from day to day. To assure plasma process performance, weight loss coupons or post-plasma destructive testing must be used. These techniques are not real-time methods however, and do not allow for immediate diagnosis and process correction. These tests often require scrapping some fraction of a batch to insure the integrity of the rest. Since these tests verify a successful cycle with post-plasma diagnostics, poor test results often determine that a batch is substandard and the resulting parts unusable. These tests are a costly part of the overall fabrication cost. A more efficient method of testing would allow for constant monitoring of plasma conditions and process control. Process anomalies should be detected and corrected before the parts being treated are damaged. Real time monitoring would allow for instantaneous corrections. Multiple site monitoring would allow for process mapping within one system or simultaneous monitoring of multiple systems. Optical emission spectroscopy conducted external to the plasma apparatus would allow for this sort of multifunctional analysis without perturbing the glow discharge. In this paper, optical emission spectroscopy for non-intrusive, in situ process control will be explored along with applications of this technique to for process control, failure analysis and endpoint determination in PWB manufacture.
Date: August 1, 1995
Creator: Ward, P.P.
Partner: UNT Libraries Government Documents Department