Department of Physics

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Colloquia & Seminars, Spring 2009

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An Informal Seminar on Mathematica: Applications to research and teaching

Speaker: Professors Jim Rabchuk, Kishor Kapale, William Polley and couple of students
Date: February 20, 2009 (Friday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
Jim Rabchuk and Kishor Kapale will lead an informal presentation and discussion about the uses of Mathematica in research   and in teaching with faculty and students interested in learning about   the program and what it can do. Examples using Mathematica will be   presented.

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Atomic Gas around Super-massive Black Holes in the Youngest Radio Galaxies

Speaker: Esteban D. Araya, Jansky Fellow National Radio Astronomy Observatory & University of New Mexico
Date: February 27, 2009 (Friday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
Radio galaxies are among the most energetic objects in the Universe. They are powered by super-massive black holes that accrete material and drive large radio jets. In this talk I will discuss studies of a particular type of radio galaxies known as Compact Symmetric Objects, that are the likely progenitors of the largest radio galaxies. I will focus on very high angular resolution observations of atomic hydrogen toward the galaxy B2352+495, that were obtained with the Very Long Baseline Array (VLBA) - a radio interferometer with antennas distributed from the Virgin Islands to Hawaii. We find evidence for a velocity gradient in the atomic hydrogen consistent with rotation around a super-massive black hole. The results support the hypothesis that compact symmetric objects are young radio sources, and indicate the possibility of conducting high angular resolution observations of atomic hydrogen to measure the mass of super-massive black holes in the youngest radio galaxies. An overview of other of my research projects will also be presented.

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Emerging active regions on the sun

Speaker: Jacob Brown
Date: March 6, 2009 (Friday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
Active regions on the Sun, is one of the unique features of the Sun's Magnetic field. As the sun rotates flux tubes come through the suns surface and create these active regions. In this talk, I will be focusing on when the active regions are first emerging from below the surface of the sun and how different features of the active regions emergence are interacting with each other to explain why they do what they do.

About the speaker:
Jacob Brown is a physics and mathematics major student from the Department of Physics, Western Illinois University.

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A Mechanical Demonstration Illustrating Parametric Resonance

Speaker: Professor James Rabchuk
Date: April 10, 2009 (Friday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
One of the most common motions observed in the world is oscillation. The simplest physical model for oscillation is the Simple Harmonic Oscillator (SHO). The form of the force responsible for this motion is given by Hooke's Law, where k is a positive constant, called the spring stiffness or spring constant. One important extension of this model is obtained when the constant k is allowed to vary with time in a periodic fashion, so that (Equation). This model is called the Mathieu equation. In contrast to the SHO, this model only results in oscillatory behavior for certain values of the parameters a and b, a phenomenon called "parametric resonance". Numerous physical systems display this kind of resonance, including several of the most important technological advances in physics and chemistry over the past 50 years; the RF Paul Ion Trap and the RF Quadrupole Mass filter. Yet, while the importance of these devices has grown, there are very few satisfactory demonstrations of parametric resonance, especially as it applies to the principles of the RF devices. In this talk, I will present a demonstration apparatus developed here at WIU which gives a remarkably clear picture of the phenomenon of parametric resonance and the principles behind RF ion traps and mass filters.

About the speaker:
Professor James Rabchuck is a physics professor from Western Illinois University. His research interests lie in the areas of hydrodynamic stability, magnetoelasticity and simulations of electromagnetic phenomena.

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Introduction to Thermoelectric Effects and Their Applications in Energy and Environment

Speaker: Professor Shang-Fen Ren
Department of Physics
Illinois State University
Date: April 15, 2009 (Wednesday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
Energy and environment are among the most important challenges facing the world in 21st century. Finding scientific solutions to meet these challenges is one of the scientists' obligations to the society. Thermoelectric effects are materials' property that can directly transfer heat into electricity and also transfer heat by electricity. With the rapid progress of nanotechnology in recent years, breakthroughs have been made in raising the materials' thermoelectric efficiency. In this talk, I will give an introduction to thermoelectric effects and their current and potential applications in energy and environment. I will also discuss the role of my own research in the searching for the most efficient thermoelectric materials.

About the speaker:
Professor Sheng-Fen Ren received her Ph.D. from Texas A&M University in 1986 and has been a Professor of Physics at Illinois State University since 1994. She is a Fellow of the American Physical Society and has received numerous grants from National Science Foundation and Research Conrporation.

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The Roger M. and Jean S. Morrow Distinguished Lecture

Spectroscopy of Semiconductors under Pressure, or Bouncing Photons off Squeezed Materials

Speaker: Professor Meera Chandrasekhar
Department of Physics and Astronomy
University of Missouri-Columbia
Date: April 16, 2009 (Thursday)
Time: 7 p.m.
Room: 205 Currens Hall

Abstract
Pressure is a powerful tool in the study of solids. When materials are squeezed so that their inter-atomic or inter-molecular separations are decreased by just two or three percent, drastic changes can occur in their properties. This talk will focus primarily on semiconducting materials, which are a class of materials that have electrical conductivity between that of metals and insulators. The most famous semiconductor is silicon, which is the basic material used in the electronics industry. In applications that involve the production of light, gallium arsenide (GaAs) is often used, for example, in light-emitting diodes. When enough pressure is applied, the grey-colored GaAs turns red. Twisted molecular arrangements of organic semiconductors may become flat. I will discuss how we apply hydrostatic pressure using a diamond anvil cell, and what we learn when we use light as a probe to investigate the changes that occur in inorganic and organic semiconductors.

About the speaker:
Professor Meera Chandrasekhar obtained her Ph.D. in Physics from Brown University. After a post-doctoral fellowship at Max-Planck-Institute in Stuttgart, W. Germany, she came to the University of Missouri-Columbia in 1978, where she is currently a Professor of Physics. She has received several distinguished awards for her research, teaching and her work with K-12 students, including the Presidential Award for Excellence in Science, Mathematics and Engineering Mentoring in 1999, the Curators' Distinguished Teaching Professorship in 2004, and the Presidential Award for Outstanding Teaching in 2006. She is a fellow of the American Physical Society, with numerous grants and publications.

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Part 1. Physics Outreach and Professional Development Efforts at Missouri University

Part 2. Pressure Studies of Organic Semiconductors

Speaker: Professor Meera Chandrasekhar
Department of Physics and Astronomy
University of Missouri-Columbia
Date: April 17, 2009 (Friday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract 1
The Department of Physics and Astronomy has conducted several outreach programs over the years, including the Physics Open House and K-12-centered projects. Our recent effort focused on professional development for 9th grade teachers, so that they can teach a year-long course in physics for high-school freshmen. In this 3-year project, entitled A TIME for Physics First, we developed curriculum based on inquiry and modeling methods, and trained 70 teachers in 25 Missouri school districts.

Abstract 2
I will describe our studies of structure-property relations in organic semiconductors using hydrostatic pressure as a tool to tune the properties. We have studied planar and non-planar molecules with high luminescence efficiencies. These materials are of interest for the production of optical devices such as LEDs. Slight variations in the choice of functionalizing side chains result in dramatic differences in the inter- and intra-chain structures in these molecules. Through photoluminescence (PL) and Raman scattering studies under pressure we are able to understand changes in the conformation of the molecules, and consequent changes in their electronic and vibrational structure.

About the speaker:
Professor Meera Chandrasekhar obtained her Ph.D. in Physics from Brown University. After a post-doctoral fellowship at Max-Planck-Institute in Stuttgart, W. Germany, she came to the University of Missouri-Columbia in 1978, where she is currently a Professor of Physics. She has received several distinguished awards for her research, teaching and her work with K-12 students, including the Presidential Award for Excellence in Science, Mathematics and Engineering Mentoring in 1999, the Curators' Distinguished Teaching Professorship in 2004, and the Presidential Award for Outstanding Teaching in 2006. She is a fellow of the American Physical Society, with numerous grants and publications.

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Exploring exotic matter through the quantum manipulation of dipolar atoms

Speaker: Professor Benjamin Lev
Department of Physics
University of Illinois Urbana-Champaign
Date: April 24, 2009 (Friday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
Highly magnetic atoms such as dysprosium offer the ability to create strongly correlated matter in both atomic physics and quantum optics settings. In addition, these atoms will form the key ingredient in novel devices possessing unsurpassed sensitivity and resolution for the microscopy of condensed matter materials. Our group aims to develop technology to perform the first laser cooling---and subsequent trapping in atom chips and optical lattices---of dysprosium and similar lanthanides. This will lead to three research projects: the investigation of quantum liquid crystal physics in 2D Fermionic dipolar lattices; the exploration of non-equilibrium quantum phase transitions in many body cavity QED; and the development of atom chip microscopy at the 10-10 magnetic flux quantum level.

About the speaker:
Professor Benjamin Lev is a physics professor from the Department of Physics, University of Illinois at Urbana-Champaign. His research focuses on experimental ultra-cold atomic and molecular physics, quantum optics, and quantum information science. http://research.physics.uiuc.edu/Lev/LevLab/Home.html

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The Solar-Stellar Connection

Speaker: Professor James E. Neff
Department of Physics and Astronomy
College of Charleston
Date: April 29, 2009 (Wednesday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
There are two cutting edges of astrophysics. The limelight usually shines on discoveries that expand the frontiers of the known universe, but it is the other extreme (the nearest stars) that allows us to extend our detailed physical understanding further into the universe. The outer atmospheres of stars serve as a large-scale plasma physics laboratory and as a tool for understanding "magnetic activity" on the Sun. The Earth resides in a space environment dominated by solar activity, and the Sun dominates all other drivers for our climate. A better understanding of stellar astrophysics can therefore lead to a better understanding of the history and evolution of the Earth and its climate. I will describe experimental techniques that are advancing our understanding stellar magnetic activity.

About the speaker:
Prof Neff is a Professor of Physics and Astronomy at College of Charleston and is an observational astronomer.

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Orbital Angular Momentum of Light for Fun and Profit

Speaker: Professor Kishor T Kapale
Department of Physics
Western Illinois University
Date: May 1, 2009 (Friday)
Time: 4 p.m.
Room: 205 Currens Hall

Abstract
Polarization is a well known and extensively utilized property of light, analog of which for matter, say electron, is its spin. On the other hand, orbital angular momentum (OAM) of light is a relatively unknown concept even though matter is known to have orbital angular momentum both in classical as well as quantum regimes. Light OAM is inherently quantum in nature and has recently become a topic of intense theoretical as well as experimental inquiry. In this talk I will introduce the concept of OAM of light, discuss methods for generation and detection of light with OAM---that's all fun! It is natural to ask what is this new property of light useful for, to know how to profit from it. I will discuss a variety of applications from the work of others as well as mine encompassing fields of biology, quantum communication, gyroscopy and astronomy.

About the speaker:
Professor Kishor Kapale is a faculty at the Department of Physics, Western Illinois University. Professor Kapale is a theoretical physicist whose research focuses on quantum optics, atomic optics, quantum information theory and applied quantum physics.