9410527 Weiss This research program, supported in the Analytical and Surface Chemistry Program, is focussed on developing an understanding of the scanning tunneling microscope for determining molecular structure and spectra of adsorbed species. The effects of local structure, defects and adsorbate interactions on surface chemical and physical properties are studied in systems ranging from isolated rare gas atoms and aromatic molecules to self asembled monolayers and polymer films. Instrumental development and expansion of the capabilities of the scanning probe microscope, including the development of the tunable microwave frequency AC STM, form a large fraction of the research effort. Real systems of fundamental and technological interest will be examined using scanning probe microscopy in these studies. %%% Scanning tunneling microscopy has proven to be an invaluable method for the examination of the detailed structure of surfaces and molecules adsorbed on surfaces. The research supported in this program addresses the detailed understanding of the imaging mechanism operative in scanning probe microscopy. A full understanding of the mechanism of image formation will enable the development of improved scanning probe methods, increasing the range of interesting and technologically important surfaces and adsorbed overlayers which can be probed with these methods. This instrumentation development forms a large fraction of the work supported here.
