Physical Sciences and Mathematics Commons^™

Charge On Luminous Bodies Resembling Natural Ball Lightning Produced Via Electrical Arcs Through Lump Silicon, Christina L. Porter, Galen P. Miley, David J. Griffiths, Erik J. Sánchez

Physics Faculty Publications and Presentations

A phenomenon resembling natural ball lightning can be produced via electrical arcing through silicon. We use lump silicon instead of silicon wafers to achieve higher production rates and larger, longer-lived luminous balls than previously reported. The luminous balls consist of a silicon core surrounded by a porous network of loosely bound silicon dioxide nanoparticles. We find that the balls carry a small net charge on the order of 10−12 C and propose that the nanoparticles are electrostatically bound to the core due to this charge.

Extended Necessary Condition For Local Operations And Classical Communication: Tight Bound For All Measurements, Scott M. Cohen

Physics Faculty Publications and Presentations

We give a necessary condition that a separable measurement can be implemented by local quantum operations and classical communication (LOCC) in any finite number of rounds of communication, generalizing and strengthening a result obtained previously. That earlier result involved a bound that is tight when the number of measurement operators defining the measurement is relatively small. The present results generalize that bound to one that is tight for any finite number of measurement operators, and we also provide an extension which holds when that number is infinite. We apply these results to the famous example on a 3 × 3 …

Confined Mesoscopic Fluid-Like Films Analyzed With Frequency Modulation And Acoustic Detection, Rodolfo Fernandez Rodriguez

Dissertations and Theses

Complete understanding of the physics underlying the changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like systems undergo at solid-liquid interfaces or under confinement remains one of the major challenges in condensed matter physics. Moreover, studies of confined mesoscopic fluid films are relevant to technological areas like adhesion, wetting processes and nanotribology.

This thesis addresses the interaction between two sliding solids interfaces separated by a nanometer sized gap, with emphasis on the role of the mesoscopic fluid film trapped between them. For this purpose we integrated two acoustic techniques, recently introduced by our group, into a sub-nanometer precision …

Characterization And Modeling Of Nonlinear Dark Current In Digital Imagers, Justin Charles Dunlap

Dissertations and Theses

Dark current is an unwanted source of noise in images produced by digital imagers, the de facto standard of imaging. The two most common types of digital imager architectures, Charged-Coupled Devices (CCDs) and Complementary Metal-Oxide-Semiconductor (CMOS), are both prone to this noise source. To accurately reflect the information from light signals this noise must be removed. This practice is especially vital for scientific purposes such as in astronomical observations.

Presented in this dissertation are characterizations of dark current sources that present complications to the traditional methods of correction. In particular, it is observed that pixels in both CCDs and CMOS …

Modulation Of The Cardiac Calcium Release Channel By Homocysteine Thiolactone, Laura Jean Owen

Dissertations and Theses

Elevated levels in blood serum (≥10μmol/L) of the amino acid homocysteine is strongly correlated with the incidence of heart failure (HF). We present evidence that the cyclic thioester, homocysteine thiolactone (HTL), a metabolic product of homocysteine, irreversibly modifies proteins that regulate the contractile process in cardiac muscle. Two proteins found in the sarcoplasmic reticulum (SR), the Ca²⁺ pump (SERCA2), and the ryanodine receptor (RyR2), are responsible for controlling the cytosolic Ca²⁺ concentration and hence the contractile state of the heart. While both improper Ca²⁺ handling and elevated homocysteine levels have been considered bio-markers in HF, a direct …

Slm-Based Fourier Differential Interference Contrast Microscopy, Sahand Noorizadeh

Dissertations and Theses

Optical phase microscopy provides a view of objects that have minimal to no effect on the detected intensity of light that are unobservable by standard microscopy techniques. Since its inception just over 60 years ago that gave us a vision to an unseen world and earned Frits Zernike the Nobel prize in physics in 1953, phase microscopy has evolved to find various applications in biological cell imaging, crystallography, semiconductor failure analysis, and more. Two common and commercially available techniques are phase contrast and differential interference contrast (DIC). In phase contrast method, a large portion of the unscattered light that accounts …

Open-Access Crystallography Database Administration: Preparation And Upload Of 400 Structures, Justin Shuck

PSU McNair Scholars Online Journal

Since 2004, Portland State's Nano-Crystallography Group has provided crystallographic resources including five interactive open-access databases (educational subset of the Crystallographic Open Database (COD), Crystal Morphology Database, Nano-Crystallography Database and Wiki Crystallography Database) as well as a mirror to the whole COD, which is the world's largest openaccess crystallography database (with currently over 235 thousand data entries of inorganic, organic, and metal-organic compounds as well as minerals). Before information can be stored inside of databases they must be put in Crystallographic Information Framework files (CIFs), the framework established by the International Union of Crystallography, and the worldwide standard for representing crystallographic …

Positional Control Of Plasmonic Fields And Electron Emission, Robert Campbell Word, Joseph P. Fitzgerald, Rolf Könenkamp

Physics Faculty Publications and Presentations

We report the positional control of plasmonic fields and electron emission in a continuous gap antenna structure of sub-micron size. We show experimentally that a nanoscale area of plasmon-enhanced electron emission can be motioned by changing the polarization of an exciting optical beam of 800 nm wavelength. Finite-difference calculations are presented to support the experiments and to show that the plasmon-enhanced electric field distribution of the antenna can be motioned precisely and predictively.

3d Systems' Technology Overview And New Applications In Manufacturing, Engineering, Science, And Education, Trevor Snyder, Mike Andrews, Mark M. Weislogel, Peter Moeck, Jennifer Stone-Sundberg, Derek Birkes, Madeline Paige Hoffert, Adam Lindeman, Jeff Morrill, Ondrej Fercak, Sasha Friedman, Jeff Gunderson, Anh Ha, Jack Mccollister, Yongkang Chen, John T. Geile, Andrew Paul Wollman, Babek Attari, Nathan Botnen, Vasant Vuppuluri, Jennifer Shim, Werner Kaminsky, Dustin Adams, John Graft

Physics Faculty Publications and Presentations

Since the inception of 3D printing, an evolutionary process has taken place in which specific user and customer needs have crossed paths with the capabilities of a growing number of machines to create value-added businesses. Even today, over 30 years later, the growth of 3D printing and its utilization for the good of society is often limited by the various users' understanding of the technology for their specific needs. This article presents an overview of current 3D printing technologies and shows numerous examples from a multitude of fields from manufacturing to education.

Vibrational Modes In Acoustic Gallery Scanning Probe Microscopy, Hsien-Chih Hung, Andres H. La Rosa, Rodolfo Fernandez, Bret Comnes, Richard Nordstrom

Physics Faculty Publications and Presentations

A distinct characteristic in Acoustic Gallery Scanning Probe Microscopy (AG-SPM) constitutes the use of its supporting structural frame as an acoustic resonant cavity for monitoring the nanometer-sized amplitude of its stylus-probe. Although very straightforward in its implementation, its amplitude detection sensitivity could be improved by a more thorough understanding of its working principle mechanism, as well as by a more systematic procedure to attain a closer matching between one of the cavitys acoustic resonances and the probes natural frequency. Herein, a description of the working principle of the AG-SPM is attempted from a vibrationalmode analysis perspective, and a successful specific …

Optical Injection Unlocking For Cavity Ringdown Spectroscopy, Gregory A. Bostrom, Andrew L. Rice, Dean B. Atkinson

Physics Faculty Publications and Presentations

Continuous wave cavity ringdown spectroscopy requires a rapid termination of the injection of light into the cavity to initiate the decay (i.e., ringdown) event. We demonstrate a technique that accomplishes this through pulsed optical injection of a second laser into the main laser, resulting in 20-100 MHz frequency shifts in the otherwise cavity-locked main laser sufficient to create ringdown events at 3.5 kHz. Data on the frequency shift as a function of both main laser current and relative wavelength are presented, 88 well 88 a demonstration that single exponential decays are maintained in the process.

Necessary Condition For Local Quantum Operations And Classical Communication With Extensive Violation By Separable Operations, Scott M. Cohen

Physics Faculty Publications and Presentations

We give a conceptually simple necessary condition such that a separable quantum operation can be implemented by local operations on subsystems and classical communication between parties (LOCC), a condition which follows from a novel approach to understanding LOCC. This necessary condition applies to all LOCC protocols involving any number of parties and any finite number of rounds of communication. Furthermore, it demonstrates an extremely strong difference between separable operations and LOCC, in that there exist examples of the former for which the condition is extensively violated. More precisely, the violation by separable operations of our necessary condition for LOCC grows …

Subwavelength Visualization Of Light In Thin Film Waveguides With Photoelectrons, Joseph P. Fitzgerald, Robert Campbell Word, Rolf Könenkamp

Physics Faculty Publications and Presentations

We report the visualization and quantitative analysis of electromagnetic surface fields at solid surfaces with the potential for λ/50 resolution. To illustrate this capability, we investigate patterns in two-photon photoemission images of light-diffracting structures in waveguiding, transparent thin films. The obtained micrographs show interference patterns between incident and guided light with a remarkable sensitivity to subwavelength features. We demonstrate that photoemission rates are directly related to the surface field strengths and develop a subwavelength method to calculate the surface fields from optical properties and surface topology based on the two-dimensional Kirchhoff diffraction integral. Calculated images based on this theoretical approach …

Zinc Oxide Random Laser Threshold Enhancement Via Addition Of Passive Scatterers, Zachariah M. Peterson, Rolf Könenkamp, Robert Campbell Word

Student Research Symposium

Zinc oxide (ZnO) is a wide bandgap n-type semiconductor with a variety of optical and electrical applications and many methods of fabrication. Strong optical scattering and photoluminescence from ZnO nanoparticles and films makes the material an ideal candidate for a random laser. Previous studies have shown both incoherent and coherent random lasing from ZnO films and particles agglomerations. When used as a passive scatterer in a laser dye gain medium, the addition of ZnO has been shown to improve the threshold for lasing. By combining active scattering ZnO with a passive scatterer, MgO, we show here that the lasing threshold …

Predicting The Optical Response Of A Generalized Multilayer Thin Film, A.J. Lawrence, Erik J. Sánchez

Student Research Symposium

The contrast mechanism in Kerr imaging is the apparent angle through which the plane of polarization is rotated upon reflection from a magnetic surface, and this can be calculated for a well characterized surface given the polarization state of the incident light. As in traditional optical microscopy, the spatial resolution is limited by diffraction to roughly half the wavelength of the illumination light. The diffraction limit can be circumvented through the use of near-field scanning optical microscopy, in which the illumination source is an evanescent field at the tip of a tapered optical fiber. The complication in merging these two …

Approximate Equations Of State In Two-Temperature Plasma Mixtures, John D. Ramshaw, Andrew W. Cook

Physics Faculty Publications and Presentations

Approximate thermodynamic state relations for multicomponent atomic and molecular gas mixtures are often constructed by artificially partitioning the mixture into its constituent materials and requiring the separated materials to be in temperature and pressure equilibrium. Iterative numerical algorithms have been employed to enforce this equilibration and compute the resulting approximate state relations in single-temperature mixtures. In partially ionized gas mixtures, there is both theoretical and empirical evidence that equilibrating the chemical potentials, number densities, or partial pressures of the free electrons is likely to produce more accurate results than equilibrating the total pressures. Moreover, in many situations of practical interest …

Surface Plasmons Of A Graphene Parallel Plate Waveguide Bounded By Kerr-Type Nonlinear Media, H. Hajian, A. Soltani-Vala, M. Kalafi, Pui T. Leung

Physics Faculty Publications and Presentations

The exact dispersion relations of the transverse magnetic surface plasmons (SPs) supported by a graphene parallel plate waveguide (PPWG), surrounded on one or both sides by Kerr-type nonlinear media, are obtained analytically. It is shown that if self-focusing nonlinear materials are chosen as the surrounding media, the SPs localization length (LL) is decreased, while their propagation length (PL) remains unchanged, as compared to those of a typical graphene PPWG. Moreover, PL and LL of the SPs are considerably affected by adjusting nonlinear parts of the dielectric permittivities of the nonlinear media. It is found that using an appropriate defocusing nonlinear …

Bioelectrical Impedance Analysis As A Laboratory Activity: At The Interface Of Physics And The Body, Elliot Mylott, Ellynne Marie Kutschera, Ralf Widenhorn

Physics Faculty Publications and Presentations

We present a novel laboratory activity on RC circuits aimed at introductory physics students in life-science majors. The activity teaches principles of RC circuits by connecting ac-circuit concepts to bioelectrical impedance analysis (BIA) using a custom-designed educational BIA device. The activity shows how a BIA device works and how current, voltage, and impedance measurements relate to bioelectrical characteristics of the human body. From this, useful observations can be made including body water, fat-free mass, and body fat percentage. The laboratory is engaging to pre-health and life-science students, as well as engineering students who are given the opportunity to observe electrical …

3d Printing Of Crystallographic Models And Open Access Databases, Werner Kaminsky, Trevor J. Snyder, Peter Moeck

Physics Faculty Publications and Presentations

Provides a brief overview of opportunities for crystallography allowed by the recent developments in 3D printing technology. in combination with open access databases.

3d Printing Of Crystallographic Models For Interdisciplinary College Education, Peter Moeck, Werner Kaminsky, Trevor J. Snyder

Physics Faculty Publications and Presentations

Provides a brief overview of the Crystallography Open Database, and how advances in 3D printing have created opportunities in teaching of college level crystallography courses.

3d Printing & Open Access Databases For Crystallographic College Education, Peter Moeck, Jennifer Stone-Sundberg, Trevor J. Snyder, Werner Kaminsky, Saulius Grazulis, International Advisory Board Of The Crystallography Open Database

Physics Faculty Publications and Presentations

Presentation gives an overview of available open access databases of crystals and crystal structures, as well as discussions of how newly developed 3D printing technologies can be used to teach crystallography at the college level. Offers advice regarding conversion of crystallographic information files to 3D printing files, and shares news from the 3D printing of crystallographic models community.

On The Production Of The Positive Antihydrogen Ion H̄+ Via Radiative Attachment, Chris M. Keating, M. Charlton, Jack C. Straton

Physics Faculty Publications and Presentations

We provide an estimate of the cross section for the radiative attachment of a second positron into the state of the ion using Ohmura and Ohmura's (1960 Phys. Rev. 118 154) effective range theory and the principle of detailed balance. The ion can potentially be created using interactions of positrons with trapped antihydrogen, and our analysis includes a discussion in which estimates of production rates are given. Motivations to produce include its potential use as an intermediary to cool antihydrogen to ultra-cold (sub-mK) temperatures for a variety of studies, including spectroscopy and probing the gravitational interaction of the anti-atom.

Advances In Crystallographic Image Processing For Scanning Probe Microscopy, Peter Moeck, Taylor T. Bilyeu, A. Mainzer Koenig, Jack C. Straton

Physics Faculty Publications and Presentations

Brief overview of advances in image processing for scanning probe microscopes, as related to high resolution images of crystals and arrays of membrane proteins.

Kinesthetic Activities For The Classroom, Elliot E. Mylott, Justin C. Dunlap, Lester Lampert, Ralf Widenhorn

Physics Faculty Publications and Presentations

Educators have found that kinesthetic involvement in an experiment or demonstration can engage students in a powerful way. With that as our goal, we developed three activities that allow students to connect with and quantitatively explore key physics principles from mechanics with three fun physical challenges. By presenting these activities as competitions, we can challenge students to use what they know about the relevant physics to improve their performance and beat their own score or those of other students. Each activity uses an original, real-time data collecting program that offers students and educators a simple, clear method to demonstrate various …