Combined Atomic Imaging and Diffraction Studies of the Electrooxidation of Supported Metal Multilayers

The solid/liquid interface plays a fundamental role in a diverse range of physical phenomena, for example in catalysis, crystal growth and in many biological reactions that govern the building of the human body and the functioning of the brain. Unravelling the atomic structure at the solid/liquid interface remains, therefore, one of the major challenges facing surface science today for it is only by understanding the physical processes in model systems that we can extrapolate to more complex environments. The key to developing this understanding lies in the preparation and study of model surfaces with well-defined elemental reaction sites.The development of alternative methods of energy supply and storage requires major advances in materials research. Such advances may now be achieved by the manipulation of molecular and atomic-scale processes, leading to an increased understanding of the physical and chemical properties of new materials. In particular, design of these materials may become possible from fundamental principles, i.e. understanding surface properties, as distinct from the bulk material properties, by the application of modern experimental techniques. The aims of this proposal are to further the understanding of the atomic and electronic structure at the electrochemical interface particularly to develop a fundamental understanding of the oxidation and reduction of transition metal multilayer films deposited by electrochemical methods. Due to the buried nature of the electrochemical interface, it is inaccessible to most standard surface science techniques that employ strongly adsorbed electron probes to gain surface sensitivity. Study of the interface is restricted to techniques that employ penetrating radiation, such as x-ray scattering or to imaging techniques such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM). The utilization of synchrotron radiation facilities (the European Synchrotron Radiation Facility in Grenoble and the Diamond Light Source at the Rutherford Appleton Laboratory) is a key component of this project. They offer state-of-the-art equipment for performing x-ray scattering experiments with high incident x-ray flux, energy tuneability and high resolution. Using such equipment it will be possible to probe surface atomic structure and the structures of adsorbed species with sub-monolayer resolution and also to gain electronic structure information from selected interface atoms that form the boundary between the solid surface and the liquid electrolyte where electric field driven reactions occur. By combining x-ray scattering (reciprocal space information) and imaging techniques (real space information) it will be possible to build a detailed picture of a surface structure under 'real' working conditions.