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Engineering Physics Commons

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1998

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Articles 1 - 5 of 5

Full-Text Articles in Engineering Physics

Charge-Correlation Effects In Calculations Of Atomic Short-Range Order In Metallic Alloys, F. J. Pinksi, J. B. Staunton, Duane D. Johnson Jun 1998

Charge-Correlation Effects In Calculations Of Atomic Short-Range Order In Metallic Alloys, F. J. Pinksi, J. B. Staunton, Duane D. Johnson

Duane D. Johnson

The “local” chemical environment that surrounds an atom directly influences its electronic charge density. These atomic charge correlations play an important role in describing the Coulomb and total energies for random substitutional alloys. Although the electronic structure may be well represented by a single-site theory, such as the coherent potential approximation, the electrostatic energy is not as well represented when these charge correlations are ignored. For metals, including the average effect from the charge correlation coming from only the nearest-neighbor shell has been shown to be sufficient to determine accurately the energy of formation. In this paper, we incorporate such …


Mass Transfer With Chemical Reaction In The Process Of Ammonia Desorption From Aqueous Solutions Containing Carbon Dioxide, Wojciech M. Budzianowski Jan 1998

Mass Transfer With Chemical Reaction In The Process Of Ammonia Desorption From Aqueous Solutions Containing Carbon Dioxide, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Measurement Of Thin Liquid Film Drainage Using A Novel High-Speed Impedance Analyzer, K. O. Hool, R. C. Saunders, Harry J. Ploehn Jan 1998

Measurement Of Thin Liquid Film Drainage Using A Novel High-Speed Impedance Analyzer, K. O. Hool, R. C. Saunders, Harry J. Ploehn

Faculty Publications

This work describes the design and implementation of a new instrument, called the thin film impedance analyzer, which measures the rate of drainage of thin oil films. The instrument forms an oil film by elevating a planar oil–water interface into a water drop hanging from a stainless steel capillary tube immersed in the oil. The instrument measures the magnitude of the impedance of the matter between the capillary tube and a screen electrode immersed in the lower water phase. Under appropriate conditions, the capacitance of the oil film dominates the impedance. The instrument records the increase in the magnitude of …


Atomic Hydrogen Cleaning Of Inp(100) For Preparation Of A Negative Electron Affinity Photocathode, K. A. Elamrawi, M. A. Hafez, H. E. Elsayed-Ali Jan 1998

Atomic Hydrogen Cleaning Of Inp(100) For Preparation Of A Negative Electron Affinity Photocathode, K. A. Elamrawi, M. A. Hafez, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Atomic hydrogen cleaning is used to clean InP(100) negative electron affinity photocathodes. Reflection high-energy electron diffraction patterns of reconstructed, phosphorus-stabilized, InP(100) surfaces are obtained after cleaning at ∼400 °C. These surfaces produce high quantum efficiency photocathodes (∼8.5%), in response to 632.8 nm light. Without atomic hydrogen cleaning, activation of InP to negative electron affinity requires heating to ∼530 °C. At this high temperature, phosphorus evaporates preferentially and a rough surface is obtained. These surfaces produce low quantum efficiency photocathodes (∼0.1%). The use of reflection high-energy electron diffraction to measure the thickness of the deposited cesium layer during activation by correlating …


Characteriation Of Bulk, Polycrystalline Indium Nitride Grown Of Subatmospheric Pressures, Jeffrey Dyck, Kathleen Kash, Kwieseon Kim, Walter Lambrecht, Cliff Hayman, Alberto Argoitia, Michael Grossner, Willie Zhou, John Angus Dec 1997

Characteriation Of Bulk, Polycrystalline Indium Nitride Grown Of Subatmospheric Pressures, Jeffrey Dyck, Kathleen Kash, Kwieseon Kim, Walter Lambrecht, Cliff Hayman, Alberto Argoitia, Michael Grossner, Willie Zhou, John Angus

Jeffrey Dyck

Polycrystalline, wurtzitic indium nitride was synthesized by saturating indium metal with atomic nitrogen from a microwave plasma source. Plasma synthesis avoids the high equilibrium pressures required when molecular nitrogen is used as the nitrogen source. Two types of growth were observed: 1) small amounts of indium nitride crystallized from the melt during cooling and 2) hexagonal platelets formed adjacent to the In metal source on the crucible sides. The mechanism of this latter growth is not established, but may involve transport of indium as a liquid film. The crystals were characterized by electron diffraction, X-ray diffraction, elemental analysis, scanning electron …