New insight on the hydrogen bonding structures of nanoconfined water: a Raman study

Water adsorbed in nanoporous silica glass has been investigated by Raman spectroscopy. The analysis was performed as a function of temperature (from +5 to +75 °C), pore diameter (25 and 75 ° A) and by changing the nature of the substrate (from hydrophilic to hydrophobic) in order to understand the role played on the dynamic peculiarities of water arrangements both by the bare geometrical confinement and the specific interaction with surface. The experimental spectra, collected in the intra-molecular O–H stretching vibrational region, have been decomposed into a sum of sub-bands, representingwater molecule arrangements with different types of hydrogen bonding. Hence, we gave a quantitative picture of the temperature and confinement effects on the connectivity pattern.