Evaluation of stone pore size distribution by means of NMR

Nuclear magnetic resonance (NMR) is a technique that exploits magnetic properties of atomic nuclei with spin quantum number different from zero in an external magnetic field. The energy exchanges between the system and its surroundings is obtained by studying the time length needed for the spin system magnetization to reach the equilibrium value, after a selected perturbation. Therefore, NMR helps in determining the interactions between the pore walls and the hydrogen nuclei of water molecules trapped in the stone porous structure. This further gives information about the chemical-physical properties of the porous matrix. The determination of porous matrix properties in natural porous stones is a very important goal in the Cultural Heritage conservation field. Porous structure of a natural stone depends on its genesis and on its particular history.