Seminars and Colloquia, January through June, 2004

• This Week's schedule.
• Earlier Semesters.
• Typical Week's schedule.
• January 1-2, 2004's schedule.
• January 5-9, 2004's schedule.
• January 12-16, 2004's schedule.
• January 19-23, 2004's schedule.
• January 26-30, 2004's schedule.
• February 2-6, 2004's schedule.
• February 9-13, 2004's schedule.
• February 16-20, 2004's schedule.
• February 23-27, 2004's schedule.
• March 1-5, 2004's schedule.
• March 8-12, 2004's schedule.
• March 15-19, 2004's schedule.
• March 22-26, 2004's schedule.
• March 29-April 2, 2004's schedule.
• April 5-9, 2004's schedule.
• April 12-16, 2004's schedule.
• April 19-23, 2004's schedule.
• April 26-30, 2004's schedule.
• May 3-7, 2004's schedule.
• May 10-14, 2004's schedule.
• May 17-21, 2004's schedule.
• May 24-28, 2004's schedule.
• May 31-June 4, 2004's schedule.
• June 7-11, 2004's schedule.
• June 14-18, 2004's schedule.
• June 21-25, 2004's schedule.
• June 28-July 2, 2004's schedule.

Seminars and Colloquia, Typical Week:

Center for Sensors & Sensor Technologies Seminar:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Journal Club on Statistical Mechanics and Condensed Matter Physics (Informal):

Oklahoma Nanonet Informal Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, January 1-2, 2004

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, January 5-9, 2004

No talks scheduled: Prelim Exams

Oklahoma State Physics Department

Seminars and Colloquia, January 12-16, 2004

First Week of Classes

Oklahoma NanoNet Informal Seminar:

Abstract:

In this presentation, after a brief introduction of quantum size confinement and luminescence of nanoparticles, I will mainly introduce our projects on the applications of luminescent nanoparticles in displays, X-ray medical imaging and in vivo detection. In addition, I will also discuss briefly the storage luminescence, upconversion luminescence, temperature and pressure behaviors of nanoparticles we observed in Nomadics.

Oklahoma State Physics Department

Seminars and Colloquia, January 19-23, 2004

Physics Colloquium:

Abstract:

The surface functionalization of group IV semiconductors, in particular Si(100), with organic molecules promises the opportunity to create devices that exploit the combined properties of organic materials and conventional semiconductors. The adsorption and chemical bonding of organic molecules to fine-tune the chemical and physical properties of the surface has applications in chemical sensors, biological recognition, and molecular and optical electronics. To realize these applications, a fundamental understanding of the reactivity of the Si(100) surface towards various organic compounds is required. Our investigations focus on the reactivity of the carbon nitrogen triple-bond. In particular, we employ cyanogen halides (ClCN, BrCN and ICN) as models for the CN triple bond functionality in order to observe the adsorption and decomposition in a straightforward manner. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) are utilized to investigate the adsorption of cyanogen halides on the Si (100) surface. At 100 K, XPS results have shown that the CN triple bond remains intact for submonolayer exposures. The UPS spectra reveal two peaks that are assigned to the pi electrons in the CN triple bond, indicating that some fraction of XCN adsorbs molecularly at 100 K. The XPS and UPS measurements conducted at room temperature support complete X-CN bond cleavage at 298 K, leaving an intact adsorbed CN species. Upon annealing to higher temperatures, XPS and UPS measurements reveal that the CN bond is stable until approximately 700 K. At even higher temperatures, silicon carbides and nitrides form.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Journal Club on Statistical Mechanics and Condensed Matter Physics Joint with High Energy Physics:

This is a three-hour video on “superstrings, hidden dimensions and the quest for the ultimate theory,” presented on a level that should be fully accessible to all science majors. Part of it will be shown and, if there is enough interest, the other part will be shown at a later date. If there are not enough seats in PS 147, a second showing will be arranged. The program can be watched section-by-section on line at http://www.pbs.org/wgbh/nova/elegant/, where also additional information can be found.

Oklahoma State Physics Department

Seminars and Colloquia, January 26-30, 2004

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

This talk will be a case history of the birth of the Research Computing Facility (RCF), its rapid development and accompanying growing pains, some lessons learned, remaining questions and opportunities for the future. RCF at the University of Nebraska-Lincoln was formed four years ago as a result of NSF/EPSCoR funding to promote high performance computing and multi-disciplinary research. From an initial resource of an 8 cpu Origin 2000, RCF has now grown to include a 256 processor LINUX cluster named PrairieFire that initially ranked 107th on the Top500 Supercomputers list. RCF currently has users from across campus as well as off-campus, running a wide variety of commercial and in-house code on four different machines. These resources are supported with only two full-time personnel and a loyal group of graduate and undergraduate students. Our evolving model for operation and administration will be presented, with a candid assessment of its strengths and weaknesses.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma NanoNet Informal Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, February 2-6, 2004

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Joint Physics, Chemistry & Oklahoma NanoNet Colloquium:

Abstract:

There has recently been increasing interest in the chemical dynamics of solvents confined in nanostructured materials. Ultimately one would like to design nanostructured materials adapted for specific reactive or spectroscopic purposes, e.g., catalysis or sensing, by controlling the cavity/pore size, geometry, and surface chemistry. In order to develop guidelines for this design, we must first understand how the characteristics of a cavity affect the chemistry. Computational studies of nano-confined solvent systems will be presented for chemical processes involving charge transfer that are intimately coupled to the solvent dynamics (and thus should exhibit pronounced changes upon confinement). Specifically, we have simulated the steady-state optical absorption and fluorescence spectra and the time-dependent fluorescence of a solute with a charge transfer transition dissolved in a nano-confined solvent. In addition, a model proton transfer reaction occurring in a confined solvent has been studied. The effect of cavity size and shape on the spectra, dynamics, and reaction energetics will be discussed.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Journal Club on Statistical Mechanics and Condensed Matter Physics Joint with High Energy Physics:

This is a three-hour video on “superstrings, hidden dimensions and the quest for the ultimate theory,” presented on a level that should be fully accessible to all science majors. The second part of it will be shown. The program can be watched section-by-section on line at http://www.pbs.org/wgbh/nova/elegant/, where also additional information can be found.

Oklahoma State Physics Department

Seminars and Colloquia, February 9-13, 2004

Joint Chemistry, Physics & Oklahoma Nanonet Colloquium:

Oklahoma State Physics Department

Seminars and Colloquia, February 16-20, 2004

Research Presentation:

Refreshments will be served at 8:30 AM.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Oklahoma State Physics Department

Seminars and Colloquia, February 23-27, 2004

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Cancelled. Dr. Turbiner is giving three other talks at OU instead.

Physics Colloquium:

Abstract:

A Bose-Einstein condensate of trapped ultracold atomic gases in an external optical lattice shows a very interesting quantum phase transition between a Mott insulating phase and a superfluid phase. Experimentally, this phase transition can be studied in great detail due to the fact that all relevant parameters can be continuously varied across the transition. Theoretically, the system can be described by a theoretical model which is called Bose-Hubbard model. This model has been studied for some time and is quite well understood. We are introducing a non-equilibrium situation by coupling the one-dimensional system to external leads so that particles will flow into the system at one end and out of the system at the other end. Numerical diagonalization techniques are used to study the properties of this system. We will show some results for the situation where a stationary flow is established.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma NanoNet Informal Seminar:

Abstract:

Thresholdless laser emission has been observed from a fused-silica microsphere coated with HgTe quantum dots. The microsphere is made by melting the end of an optical fiber, then coated with polyelectrolyte and a sparse coverage of nanoparticles. Pump light at 830 nm is coupled into a whispering-gallery mode (WGM) from a tapered fiber, exciting nanoparticles in a band around the sphere's equator. Subsequent emission, into another WGM with high efficiency, produces laser emission in the range of 1620–1720 nm. These microlasers have potential applications in telecommunications and sensing, and this work may enable fundamental studies of cavity quantum electrodynamics.

Oklahoma State Physics Department

Seminars and Colloquia, March 1-5, 2004

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

In recent years evidence has increasingly pointed to the role of nanoscopic domains within lipid membranes as locales for the binding of anchored proteins, signal transduction, protein transport, and the binding and transport into the cell of several pathogens and toxins, including the HIV-1 virus. These domains, referred to as "lipid rafts", tend to be rich in a certain class of lipids called sphingolipids, and in cholesterol. At this time details of the sub-nanometer structures and of the interactions which drive domain formation are not known. In this talk I will describe the efforts of our group at IIT and at the University of Illinois at Urbana to use simulation as a tool to begin to probe the driving forces which underlie lateral organization in membranes.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Journal Club on Statistical Mechanics and Condensed Matter Physics:

Oklahoma State Physics Department

Seminars and Colloquia, March 8-12, 2004

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Abstract:

We model the observed glueball mass spectrum in terms of energies for tightly knotted and linked QCD flux tubes. The data is fit well with one parameter. We predict additional glueball masses.

Physics Colloquium:

Abstract:

Magnetic monopoles were predicted by Dirac over seventy years ago and fit naturally into models of elementary particle physics. Arguments for their existence are compelling but, in spite of many experimental searches, monopoles have yet to be found. We discuss some of these issues.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, March 15-19, 2004

Spring Break

Physics Colloquium:

Abstract:

The Optically Stimulated Luminescence (OSL) technique is now well established for personal dosimetry applications, having several advantages over the older Thermoluminescence (TL) technique introduced in the 60’s. However, the potential of OSL for dosimetry of heavy charged particle fields, such as the ones found in space or at high altitudes, is just beginning to be explored. (As a comparison, the TL dosimeter LiF:Mg,Ti has been used experimentally for space and aircrew dosimetry since the mid 90’s.) This talk will discuss recent results which are extremely relevant for dosimetry of heavy charged particles: the observation of OSL processes in aluminum oxide that are dependent on the ionization density caused by the radiation. It will be shown that the OSL signal contains information not only about the energy deposited in the material, but also on the type of energy deposition. Advantages over the thermoluminescence technique will also be discussed.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Journal Club on Statistical Mechanics and Condensed Matter Physics:

A few short talks will be presented in preparation for next week's APS meeting:

Based on paper by Ye Xiong, X. C. Xie and S.J. Xiong

Based on paper by Ye Xiong and X. C. Xie

Oklahoma State Physics Department

Seminars and Colloquia, March 22-26, 2004

APS March Meeting

Physics Colloquium:

Abstract:

In addition to measuring whole-body dose, the skin and extremity dose to radiation workers often requires monitoring using a separate dosimeter. For skin contamination incidents, a mathematical tool to determine the dose from the contamination event. Most of the dose from a contamination event will come from beta radiation. This presentation describes how the physics of beta transport is modeled in the computer code Varskin 3, which is currently undergoing beta testing as part of a project funded by the US Nuclear Regulatory Commission. In addition, the results of a short study to develop a finger ring dosimeter based on optically stimulated luminescence readout of α-Al₂O₃:C powder will be presented.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Oklahoma NanoNet Informal Seminar:

Abstract:

Pulsed laser deposition (PLD) uses physical processes for fabrication of layered structures in micro- and nano-dimension. PLD technique was herein used to fabricate various structures such as wave guides containing nanoparticles for random lasing, layered sol gel films doped with fullerene and metallofullerene for optical limiting applications, and film coatings of aluminum oxide on alloy surfaces for corrosion protection. Random lasing was achieved in 20-nm TiO₂ doped PPV/glass waveguide where the TiO₂ nanoparticles served as activating scatters and 150-fs pulses at 544 nm from a Ti:Sapphire laser system were used as a pumping source. Nonlinear optical techniques were employed to determine nonlinear response in fullerenes. Thickness and function of the aluminum oxide layer were analyzed with the electrochemical method.

Oklahoma State Physics Department

Seminars and Colloquia, March 29-April 2, 2004

Physics Colloquium:

Abstract:

The colloquium will give an overview of fundamental research and application of the EPR dating method and the comparison with luminescence spectroscopy. Powder spectra simulations combined with spectral deconvolution offer a promising new technique for intensity determination of interfering EPR signals. To analyze relatively complex EPR powder spectra, multi-frequency EPR measurements can be helpful, of which examples are shown for mollusc shells. Characterization of the radiation sensitivities of the different defects in quartz and carbonates using high doses clearly show the limitation of previously applied model functions. Specifically for the aluminum center in quartz, Monte-Carlo simulations demonstrate the problematic aspects and danger of applying the extrapolation method for determining the Equivalent Dose (D_E). Extended models describing the interaction of the EPR detectable defects in quartz during irradiation show reasonable agreement with experimental data.

Comparative EPR, Thermoluminescence and Radioluminescence studies on quartz indicate that the Al centre may act as the recombination site for the blue emission (470 nm), while the electron trap remains unknown. The same TL emission is shown to display a significant increase of the radiation sensitivity with applied dose in sedimentary and fired quartz. Using the comparison between the complimentary spectroscopic techniques, possible mechanisms are discussed.

Dating applications will include EPR dating of volcanic rocks and marine sediments and spatially resolved luminescence dating. The presentation will end with a brief description of possible new research activities at the Optically/Thermally Stimulated Laboratory at OSU.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Oklahoma Nanonet Informal Seminar:

Abstract:

Three-dimensional nanostructures can be fabricated by the glancing angle deposition technique. By rotating the substrate in both polar and azimuthal directions, one can fabricate desired nanostructures, such as nano-rod arrays with different shapes, nano-spring arrays, and even multilayer nanostructures. This method offers a fully three-dimensional control of the nanostructure with additional capability of self-alignment. There is almost no limitation on materials that can be fabricated into desired nanostructures. In this presentation, we will discuss the current status of the glancing angle deposition technology, its potential applications, and its future challenges.

Oklahoma State Physics Department

Seminars and Colloquia, April 5-9, 2004

Photonics Seminar:

Each of these talks will last between 30 and 40 minutes and so the seminar will be finished by 5:00 pm. Both Marty and Shelley work in Dr. John Mintmire's group. These seminars are required for IGERT students and we strongly encourage other students to participate also.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

Quantum coherence effects in atoms such as electromagnetically-induced transparency and absorption, lasing without inversion, and superradiance have become well-known in atomic physics. In this talk I will review a variety of photonic coherence phenomena that are predicted to occur in passive and active coupled optical resonators. Specifically, the effective dispersive and absorptive response of coupled resonators is derived, and used to determine the conditions for slow and fast light, coupled-resonator-induced transparency and absorption, lasing without gain, and cooperative cavity emission in these systems. These effects rely on coherent photon trapping, in direct analogy with coherent population trapping phenomena in atomic systems. I will also show that the coupled-mode equations that describe coupled-resonator dynamics are formally identical to the Schrödinger equation in the rotating-wave approximation. Notably, because these effects are predicted directly from coupled-mode theory, they are not unique to atoms, nor are they uniquely quantum in nature, but rather are fundamental to systems of coherently coupled resonators.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, April 12-16, 2004

Extra Physics Colloquium:

Postponed or Cancelled.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Joint Physics, Chemistry & Oklahoma Nanonet Colloquium:

Abstract:

The characteristic internuclear potentials exhibited by molecules lead to unusual shapes of molecular nanostructures, shapes that challenge our ordinary understanding of how such structures are prepared. Such assemblies are of substantial interest both for intrinsic assembly reasons and as current-carrying components of molecular transport junctions.

The community is now doing intensive research in both of these aspects, and this talk will focus on topics very close to this interest. In the first part we will discuss the formation of micellar molecular aggregates in solution, and their dependence upon the properties of the individual molecular components. The second part will discuss some aspects of molecular charge transport in junctions, particularly the use of molecular dynamical stereochemistry as a gating mechanism.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, April 19-23, 2004

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

The Standard Model (SM) provides a highly successful description of strong, weak and electromagnetic interactions at present energies. In combination with Einstein's general relativity, it helps lay the foundation of another successful theory, the hot big bang cosmology. Some attempts to go beyond this theoretical framework will be discussed, necessitated in part by exciting experimental discoveries, namely neutrino oscillations, CMB anisotropy, and dark energy.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

The Oklahoma Microscopy Society Spring Workshop:

Oklahoma State Physics Department

Seminars and Colloquia, April 26-30, 2004

Prefinals Week

Southwest Mechanics Lecture Series Presentation:

Abstract:

A large group at Caltech is working to develop a neural prosthetic that can aid the handicapped. This talk will first summarize our overall efforts to develop neural prostheses based on the brain's Parietal Reach Region (PRR). The PRR, whose function is briefly reviewed, encodes the arm's reaching intentions. We then describe our experimental set-up for testing this concept on primate models, and present preliminary experimental results that demonstrate the possibility of using a cognitive neural prosthetic to control external devices by pure though alone. The second half of the talk will focus on our efforts to develop a new class of "movable" electrodes that autonomously isolate a neural cell so as to optimize the recorded signal quality, and then maintain optimal signal quality using feedback. Such devices are likely to improve the reliability and robustness of future chronic neural prosthetic systems.

Photonics Seminar:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

The web is a powerful tool for extending the what, when, where, and how of student learning experiences. Online simulations exist for use as pre-lab or pre-class experiences to prepare students, or to perform virtual “experiments” that are impossible in a physical lab. Educational resources developed by top research groups are available for enrichment of standard course material. Novel curricula for physics and astronomy labs are posted online for instructors to access, modify, and use. However, few of us have the time to search out these quality teaching and learning resources, to say nothing of creating them ourselves.

This talk will introduce two projects with the goals of helping teachers and students find and use these resources: ComPADRE—a joint effort of the AAPT, APS, AAS, AIP, and SPS; and MERLOT—a consortium of higher education institutions including the Oklahoma State Regents. These online collections of materials include the tools to share, organize, comment on, and review teaching and learning resources. The use of and participation in these online collections will be explored, along with some of the creative and fun teaching resources on them.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma NanoNet Informal Seminar:

Abstract:

In 2001, Velev and co-workers demonstrated the dielectrophoretic formation of microscopic wires from solutions of gold nanoparticles [Science, 294: 397-417 (2001)]. This approach demonstrates a potentially scalable technique for organizing populations of nanoscopic building blocks into simple devices that self-interface with macroscopic electronics; hence, the step of manipulating the device to establish electrical contact is effectively eliminated. Recently, we have employed this approach to fabricate individual microwires between pre-specified points in a circuit, facilitating the characterization of the electrical properties of the wires. In this talk, I will summarize the phenomenology associated with these current conduction studies, and discuss our progress towards elucidating the mechanism of conductivity that underlies the observed behaviors.

Oklahoma State Physics Department

Seminars and Colloquia, May 3-7, 2004

Finals Week

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, May 10-14, 2004

Physics & EPSCoR Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, May 17-21, 2004

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, May 24-28, 2004

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, May 31-June 4, 2004

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, June 7-11, 2004

Oklahoma Nanonet Informal Seminar:

Note: Coffee and cookies available at 3:15 in PS 147.

Oklahoma State Physics Department

Seminars and Colloquia, June 14-18, 2004

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, June 21-25, 2004

Oklahoma Nanonet Informal Seminar:

Abstract:

The compressive failure of continuous fiber reinforced composites has received considerable attention in the recent years because it typically occurs at a stress level that is 40-50 % below the tensile strength of the composite. This paper is primarily focused on enhancing the compressive strength and stiffness of unidirectional polymer matrix composites (PMC) through a series of modifications in matrix composition using nanoparticle reinforcement, and by optimizing thermoplastic pultrusion manufacturing process variables.

Low-cost commodity resins such as polypropylene (PP), suffer primarily due to low compressive strength. Enhancement of the compressive strength of pultruded thermoplastic composites can be achieved by improving the yield strength of the surrounding matrix in shear and reducing fiber misalignment in the composite through optimization of manufacturing process variables. Increase in matrix yield strength is obtained through the use of uniformly dispersed surfactant-modified nanoclay platelets, and decreasing fiber misalignment concurrently, thereby making use of positive synergies that may exist between these effects. A single-screw extruder was used to mechanically facilitate the dispersion. This new family of materials exhibits enhanced compressive stiffness and strength of the matrix material, by including exfoliated nano-scale montmorillonite particles in the fabrication of resin pre-impregnated (prepreg) glass fiber filaments. Preliminary test results on E-Glass/PP/MMT pultruded samples indicate approximately two-fold increase in modulus and strength with only 5% nanoclay loading, without adversely affecting PP resin viscosity. Scanning Electron Micrographs (SEM) were taken to examine the failure surfaces. Transmission Electron Microscopy (TEM) revealed all platelet morphologies, namely exfoliated, intercalated and stacked structures within the samples. Dramatic improvement in compressive strength (124%) and compressive modulus (110%) were observed with relatively low nanoclay loadings. An analytical model was also developed within the framework of continuum mechanics to predict changes in the matrix yield strain and the critical shear strain within the kink band with increasing nanoclay loadings. In addition, development of a multi-scale atomistic-continuum modeling is also underway to gain fundamental insight into the strengthening mechanism.

Note: Coffee and cookies available at 3:15 in PS 147.

Oklahoma State Physics Department

Seminars and Colloquia, June 28-July 2, 2004

No talks scheduled.

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This page was prepared by Helen Au-Yang and Jacques H.H. Perk.