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Self-diffusion in fluids in porous glass: Confinement by pores and liquid adsorption layers

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dc.contributor.author Kimmich R.
dc.contributor.author Stapf S.
dc.contributor.author Maklakov A.
dc.contributor.author Skirda V.
dc.contributor.author Khozina E.
dc.date.accessioned 2018-09-17T20:47:54Z
dc.date.available 2018-09-17T20:47:54Z
dc.date.issued 1996
dc.identifier.issn 0730-725X
dc.identifier.uri https://dspace.kpfu.ru/xmlui/handle/net/134067
dc.description.abstract Diffusion coefficients of 10 different polar and nonpolar liquids filled in porous glasses with mean pore diameters of 4 or 30 nm were determined with the aid of the NMR field-gradient technique. In the time scale of these experiments (0.3 to 500 ms) diffusion coefficients were found to be time independent. Within the experimental error, no influence of the polarity of the adsorbate can be stated. The diffusion coefficients of all investigated fluids in glass with 4 and 30 nm pores were reduced by factors of 0.17 and 0.63, respectively, relative to the bulk values. This relatively weak reduction can be explained by considering the known porosities of the adsorbents. The second objective of this study was to examine the diffusion behaviour below the melting point of adsorbates in porous glass. Fluids confined in pores do not freeze at the bulk freezing temperatures. In this respect, two phases must be distinguished. A maximal two monolayer thick film adsorbed on the inner surfaces does not crystallize at all, whereas the 'free' fraction of the fluid in the pores freezes at reduced temperatures according to the Gibbs-Thompson relation. The nonfrozen surface layers form a network in which self-diffusion can be investigated. Experiments have been carried out with cyclohexane. A reduction factor of 0.06 was found relative to the extrapolated values of the entirely unfrozen fluid in porous glass with a mean pore diameter of 30 nm. It is, thus, demonstrated that molecules in adsorption layers virtually retain their translational degrees of freedom along the surfaces. The lowering of the diffusivity is mainly due to the geometric restriction rather than to the interaction with the surface.
dc.relation.ispartofseries Magnetic Resonance Imaging
dc.subject Confined liquids
dc.subject Field-gradient NMR diffusometry
dc.subject Porous glass
dc.subject Self-diffusion
dc.subject Surface layers
dc.title Self-diffusion in fluids in porous glass: Confinement by pores and liquid adsorption layers
dc.type Conference Paper
dc.relation.ispartofseries-issue 7-8
dc.relation.ispartofseries-volume 14
dc.collection Публикации сотрудников КФУ
dc.relation.startpage 793
dc.source.id SCOPUS0730725X-1996-14-78-SID0029908932


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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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