Auger-Photoelectron Coincidence Spectroscopy Studies of Surface Alloys, Ultrathin Metal Films, and Layered Compounds

w:\awards\awards96\*.doc 9801681 Bartynski This experimental research project is concerned with surface analysis using Auger-Photoelectron Coincidence Spectroscopy (APECS) focusing on local electronic properties of surface alloys, ultrathin metal films, and layered compounds. In this technique, a core photoelectron and its associated Auger electron are detected in time coincidence. This method is used to probe electronic structure with high surface specificity and to study extremely low defect concentrations on oxide surfaces. The systems under study include surface alloys Ag/Cu(100), Au/Ni(110), Pd/Cu(100 and Ag/Pd(100). The surface atoms intermix, even though the components are immiscible in the bulk. Low dimensional systems and interactions between molecular adsorbates and surface defects are also of interest. A large portion of the work is carried out at the National Synchrotron Light Source at Brookhaven National Laboratory. This research program is interdisciplinary in nature and involves one or more postdoctoral and graduate students, who receive excellent training in preparation for careers in industry, government laboratories or academia. %%% This experimental research project is concerned with advanced methods to study the outermost atomic layers of a sample. Such surface analysis methods typically employ a light (photon) beam falling on the sample, which can lead to other electron(s) and/or light being ejected. In the present work the detected particles are an electron and a photon, which are coincident in time, which is an indication that they both come from the same atomic event. This method of "Auger-Photoelectron Coincidence Spectroscopy (APECS)" is used to focus on local electronic properties of surface alloys, ultrathin metal films, and layered compounds. The systems under study include surface allo ys Ag/Cu(100), Au/Ni(110), Pd/Cu(100 and Ag/Pd(100). The surface atoms intermix, even though the components are immiscible in the bulk. Low dimensional systems and interactions between molecular adsorbates and surface defects are also of interest. A large portion of the work is carried out at the National Synchrotron Light Source at Brookhaven National Laboratory. This research program is interdisciplinary in nature and involves one or more postdoctoral and graduate students, who receive excellent training in preparation for careers in industry, government laboratories or academia. ***