Acquisition of a Low Energy Electron Microscope

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9503490 Flynn The Low Energy Electron Microscope (LEEM) is a recently- available materials characterization technique which allows low energy electrons to probe the outer layers of a solid. With LEEM it is possible first to image surface topography, second to observe diffraction from the periodicities of the near-surface structure, and third to image using photoelectrons and thus probe the spatial variation of electronic structure. These instruments are very well adapted to the examination of samples through the range from high temperature to below room temperature. In situ dynamical studies offer special opportunities to view in real time not only bulk but also surface phenomena. As LEEM instruments operate in the limit of ultrahigh vacuum where surfaces remain uncontaminated for many hours, the dynamics of surface structure and reactions thus become accessible. A further major asset is the availability in the vicinity of the sample of access ports that can house molecular beam sources for eptiaxial growth conducted before or during observations. Commercial machines which offer these powerful combinations of capabilities are just now becoming available. The time is therefore ripe for the dedicated application of a LEEM instrument to materials research problems of critical interest tot the materials research community. This machine will be used to study the real time imaging of kinetic step flow processes that occur during growth, oxidation or other reaction on the surfaces of precisely tailored samples. Our focus on the materials themselves promises to document and systematize information of this type for a variety of crystal types, in addition to the discoveries of new processes that typically rewards this type of exploratory research. This (LEEM) will be placed in the University of Illinois EpiCenter, a central facility dedicated to the crystal growth and surface processes of metals, ceramics, and semiconductors.