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Application of Soft X-Ray Appearance Potential Spectroscopy to Light Lanthanides, 4d Transition Metals, and Insulators

Description: Evaporated films of La, Ce, Yb, Y, Ag--Mn(5 percent), KCl, MnF$sub 2$, CsCl and LaF$sub 3$ were studied using the soft x-ray appearance potential spectroscopy (SXAPS) technique. Studies were also made of bulk polycrystalline samples of Y, Zr, Nb, and Mo. The results are discussed in terms of existing SXAPS theories. Several similarities between soft x-ray absorption (SXA) data and the SXAPS results are discussed, and it is shown that the SXA data can aid in the interpretation of SXAPS spectra w… more
Date: October 1, 1975
Creator: Smith, R. J.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Theoretical studies of the crystal structure of rare earths and actinides at zero temperature

Description: Accurate total energy electronic structure calculations have recently been carried out over a range of volumes for selected rare-earth and actinide elements in crystal structures, experimentally observed in these elements. Correct zero temperature crystal structures are obtained, and calculated equilibrium properties are in reasonable agreement with experiment. Results of these calculations indicate that the interactions underlying crystal structure stability are similar in itinerant f-electron… more
Date: July 1, 1993
Creator: Wills, J. M. & Eriksson, O.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Local Structure of La1-xSrxCoO3 determined from EXAFS and neutron PDF studies

Description: The combined local structure techniques, extended x-ray absorption fine structure (EXAFS) and neutron pair distribution function analysis, have been used for temperatures 4<= T<= 330 K to rule out a large Jahn-Teller (JT) distortion of the Co-O bond in La1?xSrxCoO3 for a significant fraction of Co sites (x<= 0.35), indicating few, if any, JT-active, singly occupied eg Co sites exist.
Date: January 26, 2009
Creator: Sundaram, N.; Jiang, Y.; Anderson, I. E.; Belanger, D. P.; Booth, C. H.; Bridges, F. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Atomic polar tensors and acid-base properties of metal-oxide building blocks

Description: The sensitivity of the atomic polar tensor to compositional substituents is reported for the alkali silicate series. Rotational invariants, effective atomic charge (GAPT) and charge normalized anisotropy and dipole ({alpha}{sub n} and {gamma}{sub n}) are used to characterize the charge distribution and chemical environment of the atomic sites. Comparison of {alpha}{sub n} and {gamma}{sub n} with a series of known Bronsted and Lewis acids and bases suggests that these rotational invariants may a… more
Date: February 1, 1993
Creator: Ferris, K. F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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MPSA 2004 Final Report

Description: This proposal was to support a portion of the costs of Methods in Protein Structure Analysis 2004 (MPSA2004). MPSA2004 was the 15th in the series of MPSA international conferences on protein structure analysis that began in 1974. MPSA2004 was held on the campus of the University of Washington, Seattle, WA August 29 through September 2, 2004. Twenty-four internationally recognized speakers gave invited presentations; additional participants were chosen to present short talks in the 10 topics tha… more
Date: February 18, 2006
Creator: Anderson, Carl W.
Item Type: Refine your search to only Text
Partner: UNT Libraries Government Documents Department
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X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

Description: Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s{yields}3d pre-edg… more
Date: January 1, 1996
Creator: Westre, T.E.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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New tight-binding pair potentials for mineral oxides: Application to {beta}-cassiterite (110), {beta}-tridymite (10{bar 1}0) and cristobalite (110)

Description: Tight-binding, total-energy (TBTE) methods have successfully predicted surface atomic geometries for a variety of semiconducting and insulating materials that are well described by a nearest-neighbor model of interatomic interactions. However, little work has been done on distant-neighbor models, which are required to study many important mineral oxides. In this paper we demonstrate one way in which the TBTE methodology can be extended to these materials. To illustrate this approach, we calcula… more
Date: April 1, 1992
Creator: Godin, T. J. & LaFemina, J. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A Determination of the Fine Structure Constant Using Precision Measurements of Helium Fine Structure

Description: Spectroscopic measurements of the helium atom are performed to high precision using an atomic beam apparatus and electro-optic laser techniques. These measurements, in addition to serving as a test of helium theory, also provide a new determination of the fine structure constant α. An apparatus was designed and built to overcome limitations encountered in a previous experiment. Not only did this allow an improved level of precision but also enabled new consistency checks, including an extr… more
Date: August 2010
Creator: Smiciklas, Marc
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Localized Electron States Near a Metal-SemiconductorNanocontact

Description: The electronic structure of nanowires in contact withmetallic electrodes of experimentally relevant sizes is calculated byincorporating the electrostatic polarization potential into the atomisticsingle particle Schrodinger equation. We show that the presence of anelectrode produces localized electron/hole states near the electrode, aphenomenon only exhibited in nanostructures and overlooked in the past.This phenomenon will have profound implications on electron transport insuch nanosystems. We … more
Date: April 25, 2007
Creator: Demchenko, Denis O. & Wang, Lin-Wang
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Near-Edge X-Ray Absorption Fine Structure Examination of Chemical Bonding in Sputter Deposited Boron and Boron-Nitride Films

Description: Near-edge x-ray absorption fine structure (NEXAFS) is used to examine the chemical bonding in boron and boron-nitride films sputter deposited from a fully-dense, pure boron target. Reactive sputtering is used to prepare the boron-nitride and multilayered films. Although the process of sputter deposition often produces films that lack long range order, NEXAFS reveals the distinguishing features of sp{sup 2} and sp{sup 3} hybridization that are associated with different crystalline structures. Th… more
Date: May 1, 1996
Creator: Jankowski, Alan Frederic; Hayes, J. P. & Sutherland, D. G. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Lifetime Measurement of the 2{sup +}{sub 1} state in {sup 20}C

Description: Establishing how and when large N/Z values require modified or new theoretical tools is a major quest in nuclear physics. Here we report the first measurement of the lifetime of the 2{sup +}{sub 1} state in the near-dripline nucleus {sup 20}C. The deduced value of {tau}{sub #28;2{sup +}{sub 1}} = 9.8 ± 2.8(stat){sup +0.5}{sub −1.1}(syst) ps gives a reduced transition probability of B(E2;2{sup +}{sub 1}{yields}0{sup +}{sub g.s.}) = 7.5{sup +3.0}{sub −1.7}(stat){sup +1.0}{sub −0.4}(syst) e{sup 2}… more
Date: June 28, 2011
Creator: Petri, Marina-Kalliopi; Fallon, Paul; Macchiavelli, Augusto; Paschalis, Stephanos; Starosta, Krzysztof; Baugher, Travis et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Calibration of 3D Upper Mantle Structure in Eurasia Using Regional and Teleseismic Full Waveform Seismic Data

Description: Adequate path calibrations are crucial for improving the accuracy of seismic event location and origin time, size, and mechanism, as required for CTBT monitoring. There is considerable information on structure in broadband seismograms that is currently not fully utilized. The limitations have been largely theoretical. the development and application to solid earth problems of powerful numerical techniques, such as the Spectral Element Method (SEM), has opened a new era, and theoretically, it sh… more
Date: April 23, 2005
Creator: Romanowicz, Barbara & Panning, Mark
Item Type: Refine your search to only Text
Partner: UNT Libraries Government Documents Department
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Calibration of 3D Upper Mantle Structure in Eurasia Using Regional and Teleseismic Full Waveform Seismic Data

Description: Adequate path calibrations are crucial for improving the accuracy of seismic event location and origin time, size, and mechanism, as required for CTBT monitoring. There is considerable information on structure in broadband seismograms that is currently not fully utilized. The limitations have been largely theoretical. the development and application to solid earth problems of powerful numerical techniques, such as the Spectral Element Method (SEM), has opened a new era, and theoretically, it sh… more
Date: April 23, 2005
Creator: Romanowicz, Barbara & Panning, Mark
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Invariant patterns in crystal lattices: Implications for protein folding algorithms

Description: Crystal lattices are infinite periodic graphs that occur naturally in a variety of geometries and which are of fundamental importance in polymer science. Discrete models of protein folding use crystal lattices to define the space of protein conformations. Because various crystal lattices provide discretizations of the same physical phenomenon, it is reasonable to expect that there will exist invariants across lattices related to fundamental properties of the protein folding process. This paper … more
Date: June 1, 2000
Creator: Hart, William E. & Istrail, Sorin
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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