Dynamics of phenanthrenequinone on carbon nano-onion surfaces probed by quasielastic neutron scattering

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Suresh M. Chathoth
  • Daniela M. Anjos
  • Eugene Mamontov
  • Gilbert M. Brown
  • Steven H. Overbury

Detail(s)

Original languageEnglish
Pages (from-to)7291-7295
Journal / PublicationJournal of Physical Chemistry B
Volume116
Issue number24
Publication statusPublished - 21 Jun 2012
Externally publishedYes

Abstract

We used quasielastic neutron scattering (QENS) to study the dynamics of phenanthrenequinone (PQ) on the surface of onion-like carbon (OLC), or so-called carbon onions, as a function of surface coverage and temperature. For both the high- and low-coverage samples, we observed two diffusion processes; a faster process and nearly an order of magnitude slower process. On the high-coverage surface, the slow diffusion process is of long-range translational character, whereas the fast diffusion process is spatially localized on the length scale of ∼4.7 Å. On the low-coverage surface, both diffusion processes are spatially localized; on the same length scale of ∼4.7 Å for the fast diffusion and a somewhat larger length scale for the slow diffusion. Arrhenius temperature dependence is observed except for the long-range diffusion on the high-coverage surface. We attribute the fast diffusion process to the generic localized in-cage dynamics of PQ molecules, and the slow diffusion process to the long-range translational dynamics of PQ molecules, which, depending on the coverage, may be either spatially restricted or long-range. On the low-coverage surface, uniform surface coverage is not attained, and the PQ molecules experience the effect of spatial constraints on their long-range translational dynamics. Unexpectedly, the dynamics of PQ molecules on OLC as a function of temperature and surface coverage bears qualitative resemblance to the dynamics of water molecules on oxide surfaces, including practically temperature- independent residence times for the low-coverage surface. The dynamics features that we observed may be universal across different classes of surface adsorbates. © 2012 American Chemical Society.

Citation Format(s)

Dynamics of phenanthrenequinone on carbon nano-onion surfaces probed by quasielastic neutron scattering. / Chathoth, Suresh M.; Anjos, Daniela M.; Mamontov, Eugene et al.
In: Journal of Physical Chemistry B, Vol. 116, No. 24, 21.06.2012, p. 7291-7295.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review