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Full-Text Articles in Physics

A Theoretical Model For Biased Superlattice Devices, Michael Ferner Dec 1992

A Theoretical Model For Biased Superlattice Devices, Michael Ferner

Theses

A model describing the subband structures and tunneling characteristics of superlattices is presented. The model solves the envelope function equations by the transfer matrix technique. The results are codified in a Fortran program, and the model is applied to several structures.

Superlattice have been studied extensively, however many new structures await investigation.

This model is presented as a preliminary design tool. The program allows a designer to do preliminary calculations. This type of investigation guides a designer toward a goal by making possible a large number of calculations on many different structures.


Quantitative Measurement Of Pyrolysis And Combustion Species Concentration By Molecular-Beam-Sampling-Mass-Spectrometry, Xian Zhong Oct 1992

Quantitative Measurement Of Pyrolysis And Combustion Species Concentration By Molecular-Beam-Sampling-Mass-Spectrometry, Xian Zhong

Theses

A molecular-beam-sampling apparatus utilizing both a time-of-flight mass spectrometer with vacuum ultraviolet (VUV) photoionization and a quadrupole mass spectrometer with electron impact ionization is described. These systems are used to analyze reactants and products, as well as reactive intermediates, from flow tube experiments at reduced pressures and elevated temperatures. It is shown that the quadrupole signal sensitivity can be predicted using literature cross sections which are based upon the atom hybridization within the various molecules. Measurements of the VUV photoionization sensitivity for stable species led to development of a group additivity approach to predict cross sections. This approach was extended ...


Review: 'Theory Of Dielectric Optical Waveguides,' 2nd Edition, By Dietrich Marcuse, Bradley D. Duncan Aug 1992

Review: 'Theory Of Dielectric Optical Waveguides,' 2nd Edition, By Dietrich Marcuse, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

I suppose I ought to say up front that while preparing this review I often found myself feeling very much like a student evaluating his teacher. After all, it was, in part, the first edition of Dietrich Marcuse's Theory of Dielectric Optical Waveguides (among a handful of other similar texts) from which I first studied the principles of optical waveguide theory under the demanding, yet patient and graceful guidance of Dr. Ahmad Safaai-Jazi. Thus with the utmost respect for a teacher whom I have never met, I shall try to faithfully share my thoughts and feelings regarding the second ...


Review: 'Optical Fiber Communications' (2nd Edition), By Gerd Keiser, Bradley D. Duncan May 1992

Review: 'Optical Fiber Communications' (2nd Edition), By Gerd Keiser, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

If first impressions are worth anything (and they usually are), I would have to admit that my first impression of the second edition of Gerd Keiser's now popular text Optical Fiber Communications was quite good. My compliments are hereby extended to the publisher for choosing a rather handsome cover and dust jacket. It stands in strong contrast to the text's first edition, which still ranks as probably the ugliest book I own, with color choices ranging from dull cream and "baby" blue to pale pink! I am now happy to say that this older version has been discretely ...


Optical Properties Of Γ- And Α-Ce By Spectroscopic Ellipsometry, Joo Yull Rhee Jan 1992

Optical Properties Of Γ- And Α-Ce By Spectroscopic Ellipsometry, Joo Yull Rhee

Retrospective Theses and Dissertations

We have built a rotating analyzer type ellipsometer with an ultra high vacuum sample chamber. We measured the dielectric functions of [gamma]- and [alpha]-Ce in the energy range from 1.5 to 5.4 eV to investigate the role of the 4f electron in the isostructural phase transition. [gamma]- and [alpha]-Ce were made in situ by evaporation of Ce on sapphire substrates at room temperature and at 25 K, respectively. All measurements were performed inside a UHV chamber at pressures lower than 1 x 10[superscript]-10 Torr.;The measured dielectric functions showed a thickness dependence. The thicker ...


Slip Length In A Dilute Gas, Alejandro Garcia, D. Morris, L. Hannon Jan 1992

Slip Length In A Dilute Gas, Alejandro Garcia, D. Morris, L. Hannon

Faculty Publications

We study the phenomenon of slip length using molecular dynamics and direct simulation Monte Carlo simulations of a dilute gas. Our work extends the range of Knudsen numbers that have been previously studied. In a recent paper, Bhattacharya and Lie [Phys. Rev. 43, 761 (1991)] suggest a logarithmic dependence of slip length on Knudsen number. By a simple redefinition of the mean free path, we obtain good agreement between simulation results and Maxwell theory for slip length. The anomalies seen by Bhattacharya and Lie appear to be due to their definition of the mean free path.


Slip Length In A Dilute Gas, Alejandro Garcia, D. Morris, L. Hannon Jan 1992

Slip Length In A Dilute Gas, Alejandro Garcia, D. Morris, L. Hannon

Alejandro Garcia

We study the phenomenon of slip length using molecular dynamics and direct simulation Monte Carlo simulations of a dilute gas. Our work extends the range of Knudsen numbers that have been previously studied. In a recent paper, Bhattacharya and Lie [Phys. Rev. 43, 761 (1991)] suggest a logarithmic dependence of slip length on Knudsen number. By a simple redefinition of the mean free path, we obtain good agreement between simulation results and Maxwell theory for slip length. The anomalies seen by Bhattacharya and Lie appear to be due to their definition of the mean free path.


Optical Transformations In Three-Space: Simulations With A Pc, Raymond G. Wilson, Sean M. Mccreary, Jeffrey L. Thompson Dec 1991

Optical Transformations In Three-Space: Simulations With A Pc, Raymond G. Wilson, Sean M. Mccreary, Jeffrey L. Thompson

Raymond Wilson

Using Fourier transform and convolution techniques, it is illustrated how all aspects of Fraunhofer diffraction of virtually any aperture real or complex can be calculated and displayed in two- and three-space using an IBM-compatible PC. Details of program commands using software Matlab are illustrated as well as results of plotting software Surfer. Fresnel diffraction is illustrated using Fourier transformation.