The UK Medium Energy Ion Scattering Facility: Composition and Crystallography of Surfaces and Buried Interfaces

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This proposal seeks the resources to ensure effective operation of the unique UK Medium Energy Ion Scattering (MEIS) facility for the next 4 years. As such, it aims to exploit the considerable assets both in equipment (replacement value ~ 3M) and expertise that exist at the Daresbury Laboratory near Warrington. Funding is needed to provide manpower, consumables and eqipment to ensure the facility runs efficiently and continues to create the potential for new experiments in research areas not previously explored. MEIS is a technique which provides compositional and structural information with a depth resolution approaching that of a single atomic layer. Probing ions scatter from atoms in the target in elastic billiard ball like collisions losing energy to the recoiling atoms. Energy analysis of the scattered ion enables the elemental identity of the atom to be established, while additional smaller energy losses due to inelastic electronic excitations allow the determination of the depth of the target atom below the surface. High-energy resolution ensures atomic-scale depth sensitivity. The elastic scattering also gives rise to 'shadowing' of one atom by another on the incident and outgoing trajectories, and the resulting variations of scattered yield with scattering angle provide layer-specific structural data. Consequently, MEIS provides unique compositional and structural information on the surface and sub-surface properties of solids and ultra-thin films. The outstanding capabilities of the MEIS instrument at Daresbury, coupled with its unique status as a user facility, offer UK scientists the ability to study a range of surface and near surface phenomena in fundamental and applied science, much of which underpins key technological areas as diverse as:- Catalysts, where research is envisaged to study the role segregation in the effectiveness of bimetallic catalysts and also the possibility of making catalysts capable of producing chirally pure products.- Magnetic multilayer materials like those found in modern data storage devices such as hard disc drives- Silicon processing techniques for advanced devices such as computer processors and memory chips (including growth, implantation and metallisation)- Corrosion protection for architectural, aerospace and automotive applications along with more specialised products such as medical implants - Novel semiconductor materials that could be used in future generations of electronic goods (spintronic devices and quantum dots) The user programme comprises both fundamental studies of model systems and technological studies of 'real-world' materials. Since the facility is open to all academic users, new applications in novel areas can be expected to emerge during the funding period.