Studies of water at inorganic solid surfaces
After a brief review of calorimetric evidences from experiments performed on confined water, we describe the results of a neutron diffraction experiment performed on water confined in MCM41-S-15. This, inequivocally shows that, when the size of the confining volume is small enough, water occupies the available volume in a seriously inhomogeneous manner and that the coexistence of different phases, microcrystals and void regions cannot be excluded. Upon cooling the sample a more uniform filling of the pores can be obtained, and the microscopic structure of water changes accordingly, recovering a more tetrahedral simmetry. The consequences of these results on the interpretation of other independent experiments are also considered.