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Associate Professor
Ph.D.,University of South Carolina
Development and characterization of new nanoparticle-based materials

My present research centers around the synthesis and characterization of new types of composite materials that exhibit interesting and useful optical properties. The majority of the current work involves the inclusion of metal spheres only a few nanometers across into amorphous materials such as polymers and glass. Probable uses for these new composites include new lasing materials, active camouflage, new flat optical displays, and electrically-tunable optical filters. In addition to these projects, we are involved in a collaboration with Drs. H. H. Richardson (Chemistry) and M. E. Kordesch (Physics) to fabricate highly-efficient light-emitting devices from III-nitride semiconductors.

The metal nanoparticles that we study have optical and electronic properties that differ from those of macroscopic metal specimens. These differences arise from the extreme spatial confinement of the conduction electrons in these particles. Our interest in these nanoparticles stems from a few key optical properties:

• they absorb light 100 to 1,000 times more strongly than do typical organic dye molecules,

• their colors depend strongly upon their interactions with neighboring particles, and

• they induce unusual (and sometimes paradoxical) behavior in nearby luminescent molecules.

These properties alone make metal nanoparticles intriguing entities. By doping them into appropriate materials, we are able to either improve upon existing properties of the host material, or, in some cases, confer functionality that is not present in the host material alone. Below are the descriptions of two projects currently underway in my laboratory that involve nanoparticle-containing composites.

V. I. Dimitrova, P. G. Van Patten, H. H. Richardson, M. E. Kordesch, "Visible Emission From Electroluminescent Devices Using an Amorphous AlN:Er³⁺ Thin-Film Phosphor," Appl. Phys. Lett. 77 , 2000, 478-479.

P. G. Van Patten, A. P. Shreve, R. J. Donohoe, "Structural and Photophysical Properties of a Water-Soluble Porphyrin Associated with Polycations in Solutions and Electrostatically-Assembled Ultrathin Films," J. Phys. Chem. B 104, 2000, 5986-5992.

J. Chen, M. A. Reed, C. L. Asplund, A. M. Casses, A. M. Rawlett, P. G. Van Patten, M. L. Myrick, J. M. Tour, "Placement of Conjugated Oligomers in an Alkanethiol Matrix by STM Lithography," Appl. Phys. Lett. 75, 1999, 624-626.

J. D. Noll, M. A. Nicholson, P. G. Van Patten, C.-W. Chung, M. L. Myrick, "The Templated Electrochemical Synthesis of Nanoscale Polypyrrole Wires on HOPG Defects and Circular Oxidative Etch Pits," J. Electrochem. Soc. 145, 1998, 3320-3328.

X. Shi, D. Q. Li, M. Lutt, M. R. Fitzsimmons, P. G. Van Patten, "Self-Assembled Multilayers and Photoluminescence Properties of a New Water-Soluble Poly(para-Phenylene)," Mat. Res. Symp. Proc. 488, 1998, 133-138.