Auger-Photoelectron Coincidence Studies of Solids and Their Surfaces

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9411610 Bartynski A technique of Auger-photoelectron coincidence spectroscopy (APECS) with synchrotron radiation will be employed to study the core level line shapes and Auger electron spectra in selected metals, semiconductors and oxides. The enhanced sensitivity of APECS will be used to study the core level shifts, charge transfer, and electronic structure at the clean and adsorbate covered surfaces. With the ability of APECS to eliminate lifetime broadening, we will probe the line shapes of 3p (4p) core levels in several 3d (4d) transition metals for surface shifts and hidden splittings. Site- specific electronic properties and correlation effects in inhomogeneous solids will also be studied by measuring core-valence (CVV) Auger transitions coincidence with shifted core levels. Finally, we will use the unique capabilities of APECS to explore the photoexcitation/decay process itself. The majority of the research will be performed at the National Synchrotron Light Source of Brookhaven National Laboratory. Our group has developed Auger-photoelectron coincidence spectroscopy using synchrotron radiation as a new experimental probe of solids. This is a qualitative improvement over conventional Auger electron or photoelectron spectroscopy. It is more surface sensitive, it eliminates background signal, it sharpens spectral lines, and it provides a new and unique way to study the local electronic properties of complicated systems. The technique will be utilized to obtain new information about the electronic structure and bonding at clean and adsorbate covered semiconductor and metal surfaces. The site-specific nature of the technique will be used to probe the electronic properties of different atoms in solid compounds. The sharper spectral lines will allow new ways to investigate magnetic effects and electronic interactions in solids. Finally the unique capabilities of this technique will provide clues to the photoexcitation/decay process itself. The ma jority of the research will be performed at the National Synchrotron Light Source of Brookhaven National Laboratory. ***