Surface Science at ORNL

Oak Ridge National Laboratory has several projects related to the Chemistry and Physics at surfaces with clear relevance to heterogeneous catalysis. The goal of these projects is to achieve increased understanding of the fundamental aspects of the structure of solid surfaces, growth of films on solid surfaces, electronic and magnetic properties of surface or interactions and reactions of gases, liquids, or ions at surfaces. This work spans the Physical Sciences Directorate.

The Surface Chemistry and Heterogeneous Catalysis group in the Chemical Sciences Division studies molecular interactions at model catalytic systems using a variety of surface analytical techniques. Primary interest focuses on understanding how metals interact synergistically with oxide supports to control the surface chemistry that occurs on the model catalytic systems. A variety of UHV based techniques are used to prepare and probe the structure and composition of surfaces including x-ray photoemission, reflection absorption infra-red spectroscopy, thermal desorption, low energy electron diffraction and auger electron spectroscopy. A beamline is maintained at the National Synchrotron Light Source for the purpose of using soft x-ray photoemission and near edge x-ray absorption spectroscopy to probe molecular orientation and chemical transformations on surfaces.

The Scanning Probes and Nanoscale Physics group at ORNL's Center for Nanophase Materials Sciences seeks to map functionality of materials at nanoscale dimensions including magnetism, metal-insulator transitions, quantum criticality, superconductivity, and ferroelectricity. One emphasis area includes synthesis and characterization of highly oriented transition metal oxide surfaces, including oxides which may have important catalytic function. These are prepared in a system using laser MBE growth in high pressure ozone and characterization tools such as RHEED, XPS, AES, LEED and variable temperature SPM. New scanning probe microscopy techniques are developed for studies of atomic and electronic structure, electromechanical and transport properties in vacuum, ambient or liquid conditions. The group utilizes extensions of atomic force, scanning tunneling, and electron microscopy to visualize structure-property relationships, energy transformation pathways, and energy dissipation in complex materials, at surfaces and buried interfaces.

The Aqueous Chemistry and Geochemistry group in the Chemical Sciences division has understanding liquid-solid interfaces as one of their focus areas. A suite of unique facilities, including high temperature densimeters, vapor pressure and volatility apparatus, calorimeters, pH measurement cells, hydrogen-service pressure systems, and isotope-ratio mass spectrometers are applied in these studies. These capabilities are augmented through extensive collaborations to provide access to additional specialized techniques for molecular-level studies of oxide/water interfaces and the properties of fluids under nanoscale confinement in porous and fractured media.