Total scattering based on spallation neutron diffraction is a powerful method to determine the effective atomic pair distribution function (PDF) in materials. PDF is a quantitative measure of every pair of atoms probed in a diffraction experiment (internal particle structure, surface absorbed species, and interface correlations) and thus contains an unexploited wealth of information for finite systems. At present, the PDF analysis of the fluid phase and the non-periodic/highly disordered interface with the solid phase is interesting for model validations and challenging for experimental designs. Several neutron total scattering results display the promising sensitivity for probing ligand and light species (e.g., H2O) at the surface of oxide and metal nanoparticles. The new in-situ Neutron Powder Diffractometer (NPDF at LANSCE-LC) pressure cell apparatus was designed to extend the temperature (up to 750K) and pressure (up to 100MPa) conditions for various energy applications, such as sorption of fluids and gas uptake/storage. The primary goal is to study the atomic structure information of supercritical CO2 and other fluids/gases of interest when they interface with solid surfaces under non-ambient conditions. Special attention is paid to supercritical and subcritical CO2 and their applications to carbon storage in subsurface reservoirs (e.g., how the invading CO2 fluid mediates the early stages of calcite-H2O-CO2 interactions).

High-pressure fluid cell for NPDF instrument: Probing interface reactions for finite systems

247th National Meeting (2014)

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