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 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.Solids 352, 4583
(2006) .
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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.