COLL 399 |
| Jess P. Wilcoxon1, Billie L. Abrams2, and Paula P. Provencio1. (1) Dept. 1122, Sandia National Laboratories, Mail Stop 1421, Albuquerque, NM 87185-1421, (2) Dept. 1123, Sandia National Laboratories, Mail Stop 1421, Albuquerque, NM 87185-1421 |
| The optical properties of metallic nanocrystals or quantum dots (QDs) depend on the size of the cluster due to quantum confinement of the electrons and well as classical effects such as damping of the optical plasmon due to scattering at the interface with the embedding medium. To explore the effect of size, shape, and chemical interface on the optical properties of such metallic QDs in a highly dispersed state we have developed high resolution size-exclusion chromatography (HRSEC) to size and shape select sub-populations of these QDs and study their size-dependent absorbance properties. We also use HRSEC as a feedback method to elucidate the synthetic variables which dominate the final cluster properties such as size dispersion. Among the systems to be discussed include such materials as Al, Au, Ag, Cu, Pd, Pt, and Sn. New non-classical features occur in the optical absorbance of the smallest clusters of Au, Ag, and Cu which correspond to the development of discrete densities of state as such clusters become molecule-like. The smallest clusters even develop visible photoluminesence as we have shown previously. Detailed studies of novel nanoclusters such as Al, Pd, and Sn using HRSEC, HRTEM and x-ray fluorescence will be presented. Acknowledgement: This work was supported by Sandia’s Laboratory Directed Research and Development program; the Defense Threat Reduction Agency; and the Division of Materials Sciences, Office of Basic Energy Research, US Department of Energy under contract DE-AC04-94AL8500. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000 |
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Nanoscience and Nanotechnology
8:30 AM-11:45 AM, Wednesday, March 31, 2004 Marriott -- Orange County 5, Oral
Division of Colloid and Surface Chemistry |