Showing papers by "Bernt Krebs published in 2009"

Dynamics of Water in Voids between Well-Defined and Densely Packed Spherical Nanocages Acting as Polyprotic Inorganic Acids

Abstract: Using quasielastic neutron scattering, we have investigated the water dynamics of powders of the compound with the stoichiometry of [Mo72Fe30O252(CH3COO)12[Mo2O7(H2O)]2[H2 Mo2O8(H2O)](H2O)91]· ≈ 150H2O. It contains about 150 crystal water molecules in the voids between the spherical {Mo72Fe30} nanocapsules, which are considered unique polytropic inorganic acids with well-defined hydrophilic surfaces due to the presence of H2O and O atoms. It has been proposed that {Mo72Fe30} can be used as a structurally well-constrained experimental model of oxide mineral surfaces for earth scientists.(1) In this respect, it is of fundamental importance to understand the dynamics of the water molecules at the surface of the nanoclusters. Our measurements show that the dynamics of these water molecules is as expected profoundly different from that of bulk water at the same temperature, especially because of the strong hydrogen bonding between the crystal and cluster surface water molecules. In fact, our data show a non-De...