Active Creation of Instrinsically Localized Vibrations in Uranium Using X-Ray and Neutron Scattering

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In real materials, nonlinear forces cause the frequencies of vibrating atoms to depend on amplitude. As a consequence, a large-amplitude fluctuation on the scale of the atom spacing can develop a frequency that does not resonate with the normal modes, causing energy to become trapped in an intrinsically localized mode (ILM)--also called 'discrete breather' or 'lattice soliton'. As temperature is increased, entropy is expected to stabilize increased concentrations of these random hotspots. This mechanism, which spontaneously concentrates energy, has been observed in analogous systems on a larger scale, but direct sightings at the atomic scale have proved difficult. Two challenges ... continued below

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Manley, M; Alatas, A; Trouw, F; Hults, W; Leu, B; Lynn, J et al. August 23, 2007.

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In real materials, nonlinear forces cause the frequencies of vibrating atoms to depend on amplitude. As a consequence, a large-amplitude fluctuation on the scale of the atom spacing can develop a frequency that does not resonate with the normal modes, causing energy to become trapped in an intrinsically localized mode (ILM)--also called 'discrete breather' or 'lattice soliton'. As temperature is increased, entropy is expected to stabilize increased concentrations of these random hotspots. This mechanism, which spontaneously concentrates energy, has been observed in analogous systems on a larger scale, but direct sightings at the atomic scale have proved difficult. Two challenges have hampered progress: (1) the need to separate ILMs from modes associated with crystal imperfections, and (2) complications that arise at high temperatures, including feature broadening and multiphonon processes. Here we solve both of these problems by actively creating ILMs at low temperatures in {alpha}-uranium using high-energy inelastic x-ray and neutron scattering. The ILM creation excitation occurs at energies ten times higher than conventional lattice excitations, cleanly separating it from modes associated with crystal imperfections. The discovery of this excitation not only proves the existence of ILMs in uranium but also opens up a new route for finding ILMs in other materials and, in the process, a new area for spectroscopy.

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PDF-file: 12 pages; size: 0.4 Mbytes

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  • Journal Name: Active Creation of Instrunsically Localized Vibrations in Uranium Using X-Ray and Meutron Scattering, vol. 77, n/a, June 24, 2008, pp. 214305; Journal Volume: 77

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  • Report No.: UCRL-JRNL-234237
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 943819
  • Archival Resource Key: ark:/67531/metadc896222

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • August 23, 2007

Added to The UNT Digital Library

  • Sept. 27, 2016, 1:39 a.m.

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  • Dec. 6, 2016, 6:44 p.m.

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Manley, M; Alatas, A; Trouw, F; Hults, W; Leu, B; Lynn, J et al. Active Creation of Instrinsically Localized Vibrations in Uranium Using X-Ray and Neutron Scattering, article, August 23, 2007; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc896222/: accessed December 15, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.