This title appears in the Scientific Report :
2016
Please use the identifier:
http://hdl.handle.net/2128/9919 in citations.
Please use the identifier: http://dx.doi.org/10.1103/PhysRevE.93.022104 in citations.
Crossover from localized to diffusive water dynamics in carbon nanohorns: A comprehensive quasielastic neutron-scattering analysis
Crossover from localized to diffusive water dynamics in carbon nanohorns: A comprehensive quasielastic neutron-scattering analysis
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...
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Personal Name(s): | Bellissent-Funel, Marie-Claire |
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Kaneko, Katsumi / Ohba, Tomonori / Appavou, Marie-Sousai / Soininen, Antti / Wuttke, Joachim (Corresponding author) | |
Contributing Institute: |
JCNS-FRM-II; JCNS-FRM-II Streumethoden; JCNS-2 Neutronenstreuung; JCNS-1 |
Published in: | Physical Review E Physical review / E, 93 93 (2016 2016) 2 2, S. 022104 022104 |
Imprint: |
College Park, Md.
APS
2016
2016-02-02 2016-02-01 |
DOI: |
10.1103/PhysRevE.93.022104 |
Document Type: |
Journal Article |
Research Program: |
Jülich Centre for Neutron Research (JCNS) FRM II / MLZ Soft Matter, Health and Life Sciences |
Subject (ZB): | |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://dx.doi.org/10.1103/PhysRevE.93.022104 in citations.
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. |