Both cryoporometry and relaxometry probe the surface-to-volume ratio of a porous material. Nuclear magnetic resonance (NMR) relaxometry uses the random motion of molecules, whereas cryoporometry uses the melting-point depression of a confined liquid. An NMR setup has been built to simultaneously perform cryoporometry and relaxometry measurements. Using materials with a well-defined pore size, i.e. silica gels, both methods are compared with the standard N2-adsorption technique, and a good correlation is found. The methods can be used in the pore size range between 1 and 100 nm. By performing NMR relaxometry during cryoporometry, more information about the pore-size distribution can be obtained. Besides for silica gels, this is demonstrated for mortar, which has a complicated pore structure.

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. Random-walk simulations of NMR dephasing effects due to uniform magnetic-field gradients in a pore. Physical Review E, 65(2), 021306-1/8. DOI: 10.1103/PhysRevE.65.021306 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A random-walk simulation program was developed to study the effect of dephasing spins in a uniform magnetic-field gradient in a porous material. It is shown that this simulation program correctly reproduces basic nuclear magnetic resonance behavior, such as the formation of a spin echo. The spin-echo decay due to dephasing in a nonrestricted medium gives the well-known exponential relation containing the cube of time, whereas the spin-echo decay due to dephasing in a porous material gives a monoexponential decay. By varying the pore size and magnetic-field gradient, the motional averaging regime and the localization regime can be simulated. Moreover, the unknown intermediate regime is investigated. By choosing the right scaling parameters, the spin-echo decay due to dephasing in a pore can be described by one master curve for all pore sizes and gradient strengths. This master curve reveals a small intermediate regime, perfectly symmetrical around the gradient for which the dephasing length is exactly equal to the structural length of the pore.

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