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| Home > Publications database > Crossover from localized to diffusive water dynamics in carbon nanohorns: A comprehensive quasielastic neutron-scattering analysis |
| Home > Publications database > Crossover from localized to diffusive water dynamics in carbon nanohorns: A comprehensive quasielastic neutron-scattering analysis |
| Journal Article | FZJ-2016-01521 |
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2016
APS
College Park, Md.
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Please use a persistent id in citations: http://hdl.handle.net/2128/9919 doi:10.1103/PhysRevE.93.022104
Abstract: Incoherent neutron scattering by water confined in carbon nanohorns was measured with the backscattering spectrometer SPHERES and analyzed in exemplary breadth and depth. Quasielastic spectra admit δ-plus-Kohlrausch fits over a wide q and T range. From the q and T dependence of fitted amplitudes and relaxation times, however, it becomes clear that the fits do not represent a uniform physical process, but that there is a crossover from localized motion at low T to diffusive α relaxation at high T. The crossover temperature of about 210 to 230 K increases with decreasing wave number, which is incompatible with a thermodynamic strong-fragile transition. Extrapolated diffusion coefficients D(T) indicate that water motion is at room temperature about 2.5 times slower than in the bulk; in the supercooled state this factor becomes smaller. At even higher temperatures, where the α spectrum is essentially flat, a few percentages of the total scattering go into a Lorentzian with a width of about 1.6μeV, probably due to functional groups on the surface of the nanohorns.
Keyword(s): Health and Life (1st) ; Condensed Matter Physics (2nd) ; Soft Condensed Matter (2nd)
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; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; Nationallizenz
; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection
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