The overall objectives of the project are to elucidate systematically the electronic properties of 1-Dimensional (1D) and 2- Dimensional (2D) nanostructures using scanning tunneling microscopy (STM), and to develop and exploit scanning probe microscopies (SPM) techniques for the manipulation and fabrication of nanostructures. STM and spatially-resolved tunneling spectroscopy will be used to characterize systematically the atomic structure and local electronic properties of single wall carbon nanotubes (SWNTs) and inorganic nanowires (NWs). These studies will (i) characterize and model the intrinsic electronic structure, and the effect of defects and intertube/interwire coupling for SWNTs and NWs, (ii) elucidate the structural distributions of SWNTs as a function of chemical processing, and (iii) explore the consequences of mechanical deformation on electronic structure and transport through SWNTs and inorganic NWs. STM and spectroscopy will also be used to characterize the fabrication, structure and electronic properties of transition metal dichalcogenide 2D nanocrystals. These investigations will (i) elucidate the mechanism of the STM tip-induced 2D nanocrystal formation in tantalum diselenide, (ii) characterize the size dependent electronic properties and effects of intercluster interactions in 2D charge density wave nanocrystals, and (iii) explore the generality of tip-induced solid-solid transformations as a method for the fabrication of 2D nanocrystals in other material systems. %%% Nanometer scale structures represent an exciting and challenging area of interdisciplinary research that could impact broad areas of technology ranging from electronics to super strong composites. A prerequisite for the realization of such applications is a greater understanding of their intrinsic and potentially unique physical properties and a greater understanding of how they can be synthesized or fabricated. The results of this project are expected to advance significantly the basic scientific understanding of the electronic properties of 1D and 2D nanostructures that are needed ultimately to exploit these materials. ***
