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Group Page
Professor
Ph.D., Oklahoma State University
Study of nanoheaters and their effect upon temperature changes at the nanometer scale
Information Understanding heat transfer at the nanoscale is essential to predict and control the thermal energy balance in nanodevices and other nanostructures. As device dimensions continue to be reduced and number densities increase, heat dissipation becomes an increasingly serious problem. This problem is exacerbated by the fact that certain pathways for heat dissipation may become less efficient at the nanoscale because the size of the nanodevice is close in scale to the phonon mean-free path (1-100 nm). We have begun to use the photothermal properties of single isolated metal nanoparticles for unique and in-depth studies of nanoscale heat transfer. We have recently shown that a single isolated metal nanoparticle can generate sufficient heat upon irradiation to induce readily observable phase changes in ice. This phenomenon can serve as the basis for a sensitive nanocalorimetry experiment in which the temperature profile around a nanoparticle heat source can be measured as a function of optical energy input. We seeks to develop a more comprehensive understanding of nanoscale heat transport from well-characterized, isolated, hot, nanometer-sized structures to a surrounding medium with known thermal properties.
Natural gas hydrates are extremely abundant in the world. The recovery of natural gases from this tremendous natural resource is hampered by major technical and commercial challenges in the recovery process. Currently, much is known about the thermodynamic stability but little is known about the kinetics of nucleation, formation, conversion, or decomposition. Gas hydrates can provide a sequestration media for CO2. If a way is found to displace the methane in the hydrate with CO2 efficiently, then an abundant carbon neutral energy source can be harvested. This project seeks to develop a more comprehensive understanding of the relationship between gas hydrate structure stability (sI or sII) and cage occupancy (small or large cage) during thermal stimulation by examining, on a molecular scale, the conversion of methane clathrate hydrate into the more stable CO2 hydrate. We will use Raman spectroscopy to ascertain rates of nucleation, conversion and dissociation of gas hydrates with and without thermal stimulation. A local (~μm size) area will be thermally stimulation by remotely exciting metal nanoparticle aggregates in the solid hydrate with visible light. These results will allow us to determine how gas hydrates respond to a thermal perturbation and will give much needed insight into the kinetic properties of this extremely abundant natural resource. Ultimately these results will be used to formulate a much needed unified hydrate kinetic model.
Selected Publications Richardson HH, Thomas AC, Carlson MT, Kordesch ME, Govorov AO, Thermo-optical Responses of Nanoparticles: Melting of Ice and Nanocalorimetry Approach. J. Electronic Materials 36(12) 1587-1593 (2007).
Govorov AO, Richardson HH, Generating Heat with Metal Nanoparticles. NanoToday 2(1) 30-38 (2007). Richardson HH, Hickman ZN, Thomas AC, Dendramis KA, Thayer GE, Ewing GE, Ice Nucleation in alpha-Al2O3, in "Physics and Chemistry of Ice" (W. F. Kuhs, ed.). Royal Society of Chemistry, (2007). Richardson HH, Hickman ZN, Thomas AC, Kordesch ME, Govorov AO, Thermo-optical properties of nanoparticles and nanoparticle complexes embedded in ice : characterization of heat generation and actuation of larger-scale effects. Mater. Res. Soc. Symp. Proc. 964 R03-18 (2007). Richardson HH. 2D-IR Correlation and Principle Component Analysis of the Interfacial Melting of Thin Ice Films. Journal of Molecular Structure 799(1-3) 56-60 (2006). Thomas AC, Richardson HH. 2D-IR correlation analysis of thin film water adsorbed on alpha-Al2O3(0001). Journal of Molecular Structure 799(1-3) 158-162 (2006). Richardson HH, Hickman ZN, Govorov AO, Thomas AC, Zhang W, Kordesch ME. Thermooptical Properties of Gold Nanoparticles Embedded in Ice: Characterization of Heat Generation and Melting. Nano Letters 6(4) 783-788 (2006). |
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