Capillary condensation in a fractal porous medium.
Small-angle x-ray and neutron scattering are used to characterize the surface roughness and porosity of a natural rock which are described over three decades in length scales and over nine decades in scattered intensities by a surface fractal dimension D = 2.68+/-0.03. When this porous medium is exposed to a vapor of a contrast-matched water, neutron scattering reveals that surface roughness disappears at small scales, where a Porod behavior typical of smooth interfaces is observed instead. Water-sorption measurements confirm that such interface smoothing is due predominantly to the water condensing in the most strongly curved asperities rather than covering the surface with a wetting film of uniform thickness.
Broseta
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D
Institut Français du Pétrole, 92842 Rueil-Malmaison Cedex, France.
Barré
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L
Vizika
O
O
Shahidzadeh
N
N
Guilbaud
J P
JP
Lyonnard
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S