The design and construction of an atomic force microscope (AFM) suitable for operation in an ultra-high vacuum environment (UHV) will be carried out in this project. The AFM will have interchangeable cantilever-tip assemblies, in situ sample exchange, and a field ion microscope (FIM) for tip characterization. The AFM will permit fundamental studies of adhesion, wear, and surface microstructure. In particular, nanometer scale studies of the following will be carried out: (a) mass transfer caused by contact between the tip and sample; (b) nanometer scale indentation of surface and thin film mechanical properties; (c) frictional forces between the tip and sample; (d) surface structure by imaging in contact and non-contact modes. %%% The AFM will be incorporated into an existing UHV surface analysis system equipped for Auger spectroscopy, ion sputtering, and in situ polymer and metal vapor deposition of thin films. Research will focus on the surface properties of non-conducting materials, specifically ceramics, polymers, and their composites. Thin films of metals and metal oxides on these materials will also be studied. The FIM will allow the study of tip damage and mass transfer during contact under well characterized conditions. The UHV AFM/FIM system will also be capable of scanning tunneling microscopy studies.