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THz - Dynamics as a Probe of Nanostructure Alexei P. Sokolov, University of Akron, DMR 0605784

THz - Dynamics as a Probe of Nanostructure Alexei P. Sokolov, University of Akron, DMR 0605784.

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THz - Dynamics as a Probe of Nanostructure Alexei P. Sokolov, University of Akron, DMR 0605784

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  1. THz - Dynamics as a Probe of NanostructureAlexei P. Sokolov, University of Akron, DMR 0605784 • Using inelastic X-ray and Neutron scattering, we unravel the connection between damping of THz vibrations G and their excess density of states g(w) (the so-called Boson peak). The results provide a way to analyze structural heterogeneity on a scale 1-10 nm from analysis of the THz vibrational spectra. • We discovered that compression of polymeric systems (application of high pressure) increases structural heterogeneity at the nanoscale. This result seems to be counterintuitive, but provides an explanation for the observed changes in segmental relaxation under compression. Densification of PIB (high pressure) leads to increase of the boson peak amplitude ABP, indicating increase in heterogeneity at the nanoscale. Relationship between damping of THz vibrations G and the amplitude of the Boson peak ABP in glasses Phys.Rev.Lett. 99, (2007, in print); Phys.Rev.B (2007, submitted); J.Non-Cryst.Solids352, 4583 (2006).

  2. THz - Dynamics as a Probe of NanostructureAlexei P. Sokolov, University of Akron, DMR 0605784 Broader Impact: The developed method allows analysis of nanostructure in the bulk materials and will help deeper understanding of the Dynamics of Complex Systems. Education: Under this grant, two students, J.H.Roh and B. Begen have completed their PhD. Two more PhD students, K. Kumar and L. Hong, and a post graduate student S. Pawlus have been actively involved in the research. Outreach: Our group is involved in teaching school students through the Science Fair and the University of Akron Math and Science Upward Bound Program for disadvantaged students. We also work with the Akron Global Polymer Academy to assist K-12 science instruction via distance learning and personal interaction. Dr. Sokolov works with students from Copley-Fairlawn Middle school (CFMS), in particular, helping them with preparation for Science Olympiad. The team from CFMS became 5th in the State of Ohio in 2007. This is the best achievements ever for this school. The Science Olympiad Team from the Copley-Fairlawn Middle School became 5th on the State of Ohio competition in 2007. The picture shows the team after the State award ceremony.

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