Career Development Plan

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Abstract 9624154 Frisbie This proposal addresses two separate projects which are part of general investigations of nanoscale materials chemistry. The first project, is concerned with the construction of nanoscale molecular transistors (NMTs) to determine electrical conductivity mechanisms in individual molecules and molecular aggregates. These molecular devices will operate analogously to recently developed single electron transistors based on quantum dots. To make these devices, new methods for nanofabrication with the atomic force microscope will be utilized as well as conventional electron beam writing techniques. Molecules can be placed between closely-spaced source and drain electrodes by vapor deposition, or by molecular self-assembly. The aim is to observe the Coulomb Blockade for the first time in organic materials, to achieve room temperature operation, and to demonstrate transport spectroscopy in which the energy levels available for charge transport in the molecules are revealed. Completion of these studies will result in significantly new knowledge of conductivity mechanisms in organic materials and will define an important prospective device technology for molecular electronics. For the second project, a new scanning probe technique, near-field scanning optical microscopy (NSOM), will be used to probe the optical properties of electrochemical interfaces and nanostructures with high (50 nm) spatial resolution. In particular, the aim is to show that NSOM can be used to map current density at electrochemical interfaces by imaging luminescence from certain electrochemical reactions. Investigation of luminescence from porous silicon will be conducted to verify that the light emission occurs from silicon nanostructures and to track the development of these nanostructures during growth of the porous oxide. Finally, experiments are described to use NSOM as a nanolithography tool and as a means for direct measurement of intermolecular forces with simultaneo us tip-sample contact area measurement. %%% Tremendous opportunities are arising for gaining new knowledge and developing new technology by building and studying nanoscale structures. Recent developments in molecular self-assembly technology and scanning probe microscopies in particular enable unprecedented manipulation and investigation of materials on the nanoscopic scale. This research is aimed at utilizing these new methods for probing nanoscale properties of materials and interfaces. In the first project, nanoscale molecular transistors are constructed to determine electrical conductivity mechanisms in individual molecules and molecular aggregates. These molecular devices will operate analogously to recently developed single electron transistors and offer an important prospective device technology for molecular electronics. In the second project, a new scanning probe technique is to probe the optical properties of organic materials and electrochemical interfaces with high (~50 nm) spatial resolution.