| Synthetic schemes have been developed for the preparation of organically-functionalized Au, Ag, Pt, and Pd crystalline nanoparticles (nanocrystals) in the size range of 1.0 to 10 nm. For certain of these nanocrystals, particle growth mechanisms and stabilization theories based on thermodynamic and kinetic arguments have been advanced. A host of analytical and materials characterization techniques have been utilized to probe the chemical, physical, and electronic properties of the organically-functionalized nanocrystals. In addition, procedures based on self-assembly and Langmuir-Blodgett film techniques have been developed as rational means for fabricating two- and three-dimensional close-packed ordered arrays (superlattices) of these nanocrystals on micron length scales. Moreover, "first generation" applications of these nanocrystals have been demonstrated in the areas of catalysis and single-electron solid-state devices.; The organically-functionalized nanocrystals were prepared in organic media as monodisperse (non-aggregated) colloids with narrow size distributions {dollar}(sigmaapproxpm10%){dollar} and well-defined surface compositions. These materials are soluble in organic as well as aqueous media and may be stored as powders or as colloids. In addition, they may be placed in complex chemical environments (e.g., low-temperature glasses, polymer solutions, gels, micelle solutions, etc.) to form nanocrystal-host matrix systems, and methodologies for achieving this have been developed in the present work.; The chemical and physical properties of the nanocrystals have been investigated using the techniques of XRD, TEM, UV/vis, IR, XPS, MS, NMR, DSC, TGA, and elemental analysis. The electronic properties of these nanocrystals have been probed with resistivity-temperature, current-voltage (I-V), and AC impedance ({dollar}Delta{dollar}C-V) measurements. The results of these characterization experiments demonstrate that the nanoparticles are indeed crystalline, that they are functionalized with organic molecules covalently-bound to the metal particle surface, and that they possess unique optical, electronic, and surface properties as a direct consequence of finite-size effects.; The unique properties of these nanocrystals, coupled with the ability to place and arrange them in a variety of meaningful ways have enabled "first generation" applications in catalysis and single electron solid-state devices. The positive results of these applications experiments assert the future promise of organically-functionalized metal nanocrystals as applied materials. |
