Combined NMR cryoporometry and relaxometry

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 perforin cryoporometry and relaxometry measurements. Using materials with a well-defined pore size, i.e. silica gels, both methods are compared with the standard N-2-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.