Structure and Dynamics of Vapor-deposited Aqueous Solution Glasses

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In order to clarify the origin of the low energy excitation of glasses, which is one of the important problems in the physics of disordered systems, we have measured the neutron scattering and heat capacity of glassy water and several aqueous solution glasses. Two different types of solutes were taken for this study; one is well-solved solute CD_3OH and the other is less-solved solute Xe and SF_6. CD_3OH may have the effect destroying hydrogen-bond network, and Xe and SF_6 forming hydrogen-bond network through the hydrophobic hydration forming cage-like local structure. Both glasses were prepared by the low-temperature vapor-deposition technique which was developed by us.At the beginning of the study, we have measured the neutron diffraction and small angle scattering of glassy water (solvent of the present systems) and SF_6 solution glass. Annealing the samples around 120 K, which is ca. 10 K lower than the glass transition temperature, reduced average mass density and density fluctuation around 0.1 Å^<-1>. Then we measured inelastic neutron scattering of the CD_3OH, Xe and SF_6 aqueous solution glasses with several concentrations. CD_3OH increased the intensity of the low-energy excitation while Xe and SF_6 reduced the intensity. These effects were enhanced by the increase of solute concentration. Annealing around 120 K also reduced the intensity of the low-energy excitation. By combining all of the present results, we have concluded that the origin of the low energy excitation of hydrogen-bonded network glasses is the nano-scale disorder and distortion due to partially broken hydrogen bonds.At present, the above results have been published in five international journals, We had good response in all of the eight (four overseas and four domestic) international meetings where the present results were reported.