Inelastic neutron scattering (INS) spectroscopy is a form of vibrational spectroscopy that is complementary to the conventional methods of infrared and Raman spectroscopies. Its usefulness derives from the properties of the neutron, which is a neutral particle and has a magnetic moment. Its sensitivity to all types of atomic movements makes neutron spectroscopy the experimental method of choice when detailed knowledge of the vibration spectrum of a material is requested – on the level of phonon dispersion in single crystals or vibrational density of states (VDOS) in polycrystalline samples. In particular INS is a highly sensitive to those modes that involve motion of hydrogen atoms.<br/>IN1-Lagrange is a instrument oriented to studies of lattice and molecular excitations in complex materials that has been recently installed at the high-flux neutron reactor Institut Laue-Langevin (ILL) and is fully operational since 2012. Unique at the ILL by the combination of high energy range (1-1000 meV), high count rate and flexible resolution variation in a broad range. With these characteristics Lagrange opens new possibilities for the spectroscopic studies of complex materials and in particular of water confined in porous media.<br/>A large body of experimental and simulation work convincingly shows that the structure and dynamics of water are significantly modified when water molecules are close to interfaces or confined in porous spaces. Understanding the properties of such confined water is of prime importance in numerous scientific fields, in particular environmental sciences. Neutron scattering techniques have been extensively used for the study of water confined in swelling clay minerals and here will be introduced how the INS spectroscopy can help on the understanding the properties of confined water. In particular results on the recent studies of the orientation-dependent vibration spectra of water molecules confined in the interlayer space of synthetic saponite by means of INS and Density Functional Theory (DFT) calculations.<br/><br/>

Inelastic neutron scattering techniques for the study of water confined in swelling clay minerals

249th National Meeting (2015)

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