Bulletin of the American Physical Society
2005 72nd Annual Meeting of the Southeastern Section of the APS
Thursday–Saturday, November 10–12, 2005; Gainesville, FL
Session GD: Nanoscience I |
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Chair: Steve Hill, University of Florida Room: Hilton Hickory |
Friday, November 11, 2005 10:45AM - 10:57AM |
GD.00001: Thermoelectric Properties of Lead Telluride/Polymer Nanocomposites Garrett May, Yi Wang, Jiye Fang, Kevin Stokes The thermoelectric properties of lead telluride/conducting polymer nanocomposites are investigated and evaluated as possible thermoelectric materials. The lead telluride nanoparticles are synthesized using high-temperature organometallic chemical techniques and have diameter less than 20 nm. The lead telluride nanoparticles are combined with a conducting polymer in varying volume fractions with $>$95 wt. {\%} semiconducting material. The resulting composite is cold-pressed into a solid. Electrical conductivity and Seebeck coefficient are measured from room temperature to 100$^{o}$C. The thermoelectric properties are reported as a function of lead telluride/polymer ratio. [Preview Abstract] |
Friday, November 11, 2005 10:57AM - 11:09AM |
GD.00002: Spectral density of fluctuations for a driven, nonlinear micromechanical oscillator at kinetic phase transition Corey Stambaugh, Ho Bun Chan We measure the spectral densities of fluctuations of an underdamped nonlinear micromechanical oscillator. By applying a sufficiently large periodic driving force, two stable dynamical states occur within a particular range of drive frequency. White noise is injected into the driving force allowing the system to overcome the activation barrier and to switch between the two states. While the system predominately resides in one of the two states for most excitation frequencies, a narrow range of frequencies exist where the population levels are approximately equal and the system is at a `kinetic phase transition' that is analogous to the phase transition of thermal equilibrium systems. By examining the power spectral densities of the measured oscillation amplitude, the fluctuation characteristics of the system can be studied. At the `kinetic phase transition' a supernarrow peak, centered at the excitation frequency, arises as a result of noise-induced transitions between the two dynamic states. A smaller, secondary peak associated with fluctuations about the two attractors is also examined. Its dependence on noise and excitation frequency is shown to be different from that of the supernarrow peak. [Preview Abstract] |
Friday, November 11, 2005 11:09AM - 11:21AM |
GD.00003: Effect of surface morphology on adsorption-induced bending of microcantilevers Ramya Desikan, Ida Lee, Thomas Thundat Microcantilevers undergo bending due to molecular adsorption when adsorption is confined to a single surface. The origin of the adsorption-induced force is assumed to be surface stress variation due to molecular adsorption. Single crystal silicon cantilevers were etched for a series of different time periods using two different types of Potassium Hydroxide solutions in order to obtain a rough and a smooth finish on the cantilever surface. Cantilevers that approximately had the same resonance frequency in the rough and smooth etched categories were chosen for comparison in the experiment. Liquid phase adsorption of 1-Do-decan-thiol on the cantilevers having a thin gold receptor was investigated with optical beam deflection method. The surface roughness of the cantilevers was quantified using atomic force microscopy imaging of the cantilever. Our results indicate that an increase in surface area does not increase the bending of a microcantilever, a smoother surface provides a better platform for the formation of a Self Assembled Monolayer. The un-etched cantilevers were used as the control and had the least deflection. [Preview Abstract] |
Friday, November 11, 2005 11:21AM - 11:33AM |
GD.00004: Optical Trapping and Torquing of Nanorods Douglas Bonessi, Keith Bonin, Thad Walker We previously trapped and studied the motion of glass nanorods with diameters in the range of 260-500 nm and lengths of 1-4 microns. Here we plan to report on optical trapping experiments using smaller rods with diameters of 100 nm or less and with different electronic properties. Once trapped, we plan to manipulate them by applying a torque, which will enable us to measure the electro-optical properties of the trapped rods, specifically their polarizability. This torque will allow us to rotate the rods both away from and near a surface and observe how the motion changes as you approach the surface. Such surface interactions are critical in micro- and nanoscale fluidics and we hope to study the influence of such interactions on the motion of optically-trapped nanorods near surfaces. [Preview Abstract] |
Friday, November 11, 2005 11:33AM - 11:45AM |
GD.00005: Synthesis and Characterization of Hydrophobic-Core Hydrophilic-Shell Nanoparticles and its Use as Encapsulating Agents for Fluorescent Probes Jorge Ch\'{a}vez, Jeffrey Wong, Randolph Duran Hydrophobic--core hydrophilic-shell nanoparticles were synthesized and used for the encapsulation of hydrophobic fluorescent dyes. The synthesis of these nanocontainers is based on a microemulsion system combining three amphiphiles, being one of them chemically active. This combination produces spherical aggregates with hydrophobic interiors and the ability to grow a chemically connected, hydrophilic shell. The non polar interior of this system offers the possibility of encapsulating hydrophobic species and, at the same time, the polar character of its periphery allows its use in aqueous environments. In this contribution, we report the characterization of the nanocapsule precursors and the final product, as well as the study of the final fate of the encapsulated agents inside the capsules. Dynamic light scattering, transmission electron microscopy and atom force microscopy were used for the characterization of the particles. The dyes used in this study, dansyl chloride and coumarin 153 are good sensors of rigidity and polarity, which was used to prove their encapsulation by fluorescence studies. This system opens the possibility for hydrophobic fluorescent probes to be used for imaging applications in biological relevant systems. [Preview Abstract] |
Friday, November 11, 2005 11:45AM - 11:57AM |
GD.00006: Making Carbon Nanotubes with an Underwater Arc. Gary Hunter, Lee Culver, Elizabeth Nelson, James Espinosa, Bob Powell The Physics Experimental Nanotechnology Group at the University of West Georgia has produced carbon nanotubes via the electric arc method. The apparatus consists of a low D.C. voltage, variable current power supply, two carbon electrodes, and a water reservoir. The arc was sustained for ten seconds, producing a carbonaceous residue on the cathode. This buildup was removed from the electrode and examined under a transmission electron microscope. Samples of nanotubes were produced in electric arcs that had direct currents ranging from 30 amps to 150 amps for a fixed voltage of 25 volts. Typical samples were 10-15 nanometers in diameter and lengths ranging up to hundreds of nanometers. [Preview Abstract] |
Friday, November 11, 2005 11:57AM - 12:09PM |
GD.00007: Effect of electron correlation in nanotubes: electron localization Russell Selva, Andrew Kinchen, Yuriy Malozovsky We study the electron correlation in the zigzag and armchair carbon nanotubes (CNT). We derived the dynamic pair interaction potential between two electrons in the tubule incorporating short-range and exchange correlation. Dispersion of plasmon modes at different values of angular momentum, and chirality angle and single-particle excitations are derived as well. We find that the plasma modes are not Landau damped with the lowest mode has acoustic behavior. We also evaluate the self-energy part due to the interaction of an electron with acoustic mode. We find that the multiple scattering of an electron on the plasma acoustic mode leads to the so-called plasmaron quasiparticle and self-localization of an electron in the polarization well. [Preview Abstract] |
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