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The dynamics of the plastically crystalline phase of cyanoadamantane revisited by NMR line shape analysis and field-cycling relaxometry

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dc.contributor.author Flämig M.
dc.contributor.author Fatkullin N.
dc.contributor.author Rössler E.
dc.date.accessioned 2020-01-21T20:31:20Z
dc.date.available 2020-01-21T20:31:20Z
dc.date.issued 2019
dc.identifier.issn 0021-9606
dc.identifier.uri https://dspace.kpfu.ru/xmlui/handle/net/157339
dc.description.abstract © 2019 Author(s). The dynamics of cyanoadamantane (CN-ADA) in its plastically crystalline phase encompasses three processes: overall tumbling of the rigid molecule, rotation around the molecular symmetry axis, and vacancy diffusion. This makes CN-ADA a prototypical case to be studied by field-cycling as well as by conventional NMR relaxometry. Data are collected from 430 K down to about 4 K and frequencies in the range of 10 kHz-56 MHz are covered. The overall tumbling is interpreted as a cooperative jump process preceding along the orthogonal axis of the cubic lattice and exhibiting a temperature independent non-Lorentzian spectral density. Consequently, a master curve is constructed, which yields model-independent correlation times, which agree well with those reported in the literature. It can be interpolated by a Cole-Davidson function with a width parameter βCD = 0.83. The uniaxial rotation persisting in the glassy crystal (T < Tg = 170 K) is governed by a broad distribution of activation energies, g(E). In this case, the standard master curve construction applied for the overall tumbling, for example, fails, as the actually probed distribution of correlation times G(ln τ) strongly changes with temperature. We suggest a scaling method that generally applies for the case that a relaxation process is determined by a distribution of thermally activated processes. Frequency as well as temperature dependence of the relaxation rate can be used to reconstruct g(E). In addition, g(E) is extracted from the proton line-shape, which was measured down to 4 K. Vacancy diffusion governs the relaxation dispersion at highest temperatures; yet, a quantitative analysis is not possible due to instrumental limitations.
dc.relation.ispartofseries Journal of Chemical Physics
dc.title The dynamics of the plastically crystalline phase of cyanoadamantane revisited by NMR line shape analysis and field-cycling relaxometry
dc.type Article
dc.relation.ispartofseries-issue 22
dc.relation.ispartofseries-volume 151
dc.collection Публикации сотрудников КФУ
dc.source.id SCOPUS00219606-2019-151-22-SID85076571465


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  • Публикации сотрудников КФУ Scopus [24551]
    Коллекция содержит публикации сотрудников Казанского федерального (до 2010 года Казанского государственного) университета, проиндексированные в БД Scopus, начиная с 1970г.

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