Bulletin of the American Physical Society
Spring 2012 Meeting of the APS Ohio-Region Section
Volume 57, Number 4
Friday–Saturday, April 13–14, 2012; Columbus, Ohio
Session F1: Materials Science and Condensed Matter Physics |
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Chair: Nancy M. Santagata, Ohio State University Room: Physics Research Building Smith Seminar Room |
Saturday, April 14, 2012 8:00AM - 8:12AM |
F1.00001: Effect of blending on nematic order in semiflexible polymers Kiran Khanal, Jutta Luettmer-Strathmann Semiflexible polymers of sufficient stiffness exhibit liquid crystalline order at sufficient polymer concentrations. In this work, we investigate blends of flexible and semiflexible polymers with the aid of Monte Carlo simulations of a bond-fluctuation model. The model is an extension of Shaffer's bond-fluctuation model, where chain stiffness is controlled by including different forms of bending penalties, and includes attractive interactions between monomers. From simulations for a range of values of the bending energy, density, and temperature, we determine the effect of concentration of the flexible polymer on liquid crystalline order. [Preview Abstract] |
Saturday, April 14, 2012 8:12AM - 8:24AM |
F1.00002: Effect of an external field on nematic order in semiflexible polymers Jutta Luettmer-Strathmann, Kiran Khanal Semiflexible polymers of sufficient stiffness exhibit liquid crystalline order at sufficient polymer concentrations. In this work, we investigate blends of flexible and semiflexible polymers under a uniform external field with the aid of Monte Carlo simulations of a bond-fluctuation model. The model is an extension of Shaffer's bond-fluctuation model, where chain stiffness is controlled by including different forms of bending penalties, and includes attractive interactions between monomers. From simulations for a range of values of the bending energy, density, and temperature, we determine the effect of an external field on liquid crystalline order. [Preview Abstract] |
Saturday, April 14, 2012 8:24AM - 8:36AM |
F1.00003: Effects of Sapphire Substrate Annealing Conditions on the Quality of ZnO Films Tom Oder, Michael McMaster, Andrew Smith, Nagaraju Velpukonda, Joshua Petrus The effects of pre-deposition annealing of sapphire substrates on the properties of sputter-deposited ZnO films were investigated. The films were deposited on sapphire substrates using radio frequency magnetron sputtering from a high purity ZnO solid target. Prior to the film deposition, the sapphire substrates were annealed in different gases including argon, nitrogen, oxygen and vacuum. The deposited films were annealed in N$_{2}$ at 900 \r{ }C for 5 min and characterized using photoluminescence spectroscopy, X-ray diffraction (XRD), Hall effect and Atomic force microscopy measurements. The optimum conditions consisted of pre-deposition annealing in oxygen. The XRD 2$\theta $-scans from all the samples had peaks at around 34.4\r{ } corresponding to the diffraction from the (0 0 0 2) plane of ZnO and indicates a strong c-axis orientation perpendicular to the surface at the sapphire substrate. The near band edge luminescence spectra had peaks with narrow line widths as small as 8.59 meV and are attributed to radiative recombination of bound excitons. The Hall effect measurements indicate n-type conductivity with high electron concentrations. [Preview Abstract] |
Saturday, April 14, 2012 8:36AM - 8:48AM |
F1.00004: Characterization of metallic adatoms on GaAs David Gohlke, Jay Gupta As semiconductor nanostructures become smaller, defects play an ever-increasing role in systems of interest. Scanning tunneling microscopy (STM) can be used to probe and manipulate systems on the atomic scale. For exceptionally clean systems, we study our samples at low-temperature (5K) and ultra-high vacuum (UHV). Here we examine the properties of charged atoms on the surface of the semiconductor gallium arsenide (GaAs). We determine the binding site and charge of these adatoms, and use this information to tune the energy levels of electron acceptors in the surface. Funding for this research was provided by the Center for Emergent Materials at the Ohio State University, an NSF MRSEC (Award Number DMR-0820414). http://www.physics.ohio-state.edu/$\sim$jgupta/ [Preview Abstract] |
Saturday, April 14, 2012 8:48AM - 9:00AM |
F1.00005: Nanoscale Assessment of Water Incursion to the Metal/Coating Interface Hyungjin Lee, Jim Browning, Mark Foster While a great deal of research on macroscopic corrosion phenomena has been done and an empirical knowledge of effective corrosion mitigation strategies is available, a fundamental understanding of many nanoscale aspects of corrosion or precorrosion processes at metal interface is lacking. Neutron reflectometry (NR) can be used to nondestructively determine depth profile of a substance near an interface with a resolution of 1-2 nm. Key precorrosion phenomena that we have focused on are ingress of small molecules such as water and salt into coating or coating/metal interface. To simulate a practical precorrosion process, an in situ experiment in which the sample is in the presence of water vapor can be performed. Samples of a thin epoxy coating containing siloxane on an aluminum substrate having a native oxide have been studied by NR. Composition depth profile of water at coating/oxide interface can be inferred using a comparison of the data from samples under dry and humid conditions. We have shown that water incursion along coating/metal interface is fast compared to incursion through face of coating. Also, our work has provided evidence that, with a more highly crosslinked coating, after a small amount of water has entered along the interface water incursion slows dramatically. [Preview Abstract] |
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