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Click here for:Date: | TBA |
Time: | TBA |
Place: | NRC TBA |
Inquiries: | sjhwang@okstate.edu or osu-clpr@okstate.edu |
Date: | Tuesday (usually) |
Time: | 3:00-4:00 PM |
Place: | NRC TBA |
Inquiries: | jpw519@okway.okstate.edu |
Date: | Tuesday (biweekly, fall semester only) |
Time: | 4:30 PM |
Place: | PS 147 |
Inquiries: | physpaw@mvs.ucc.okstate.edu |
or by phone at 4-5815 |
Date: | Thursday |
Time: | 1:30-3:00 PM |
Place: | Studio D, Classroom Building, Room 106A, OSU |
& Bizzell Library, Room 104, OU | |
Inquiries: | shaown@okstate.edu or milton@nhn.ou.edu |
Date: | Thursday |
Time: | 3:30-4:30 PM |
Place: | PS 110 |
Inquiries: | aihua@westlake.phy.okstate.edu A> or perk@okstate.edu |
Date: | Friday (bi)weekly |
Time: | 2:30 PM |
Place: | PS 147 |
Inquiries: | perk@okstate.edu |
No talks scheduled
No talks scheduled
Speaker: | Dr. Ravi Vadipalli |
Engineering Research Center | |
Mississippi State University | |
Date: | Thursday, July 18, 2002 |
Time: | 2:30 PM |
Place: | PS 147 |
Title: | Transient Effects During the Boost Phase of a Free Particle Wave-Packet |
In view of the conceptual advantages of particle-like behavior of the wave-packet, and with widespread availability of massively parallel and distributed computing environments, quantum fluid dynamics (QFD), based on Bohm's hydrodynamic formalism [1], has regained much interest during the recent past. Borrowing techniques from computational fluid dynamics (CFD), Lopreore and Wyatt [2] derived and implemented governing equations of the quantum trajectory method (QTM), based on the QFD formalism, on a sequential computing environment. Brook et al. [3] parallelized the QTM on OpenMP architecture using a partially implicit scheme. Brook et al. [3] also performed accuracy study of a propagating wave-packet for free particle. These studies exhibited unfavorable relative error for probability density. This presentation offers a method to remove the observed anomalies without compromising for the accuracy. In view of the limitations of OpenMP, we implemented an MPI version of the code with fully explicit scheme. Details of our implementation will also be discussed.
References:
Host: J. W. Mintmire, mintmir@okstate.edu.
Speaker: | Dr. W.G. Harter |
Department of Physics | |
University of Arkansas | |
Date: | Tuesday, July 23, 2002 |
Time: | 2:30 PM |
Place: | PS 110 |
Title: | Nothing-Going-Nowhere-Fast and A New Old-Time Revival: |
Wave Interferometric Theory of Relativity, Quantum Dynamics, Revivals and Computers |
Faster-than-light wave motion is a more common and useful phenomenon than is generally appreciated. Extreme wave velocities are not, as has been suggested, a threat to modern QED, but serve instead as a surprisingly simple recapitulation of it. Faster-than-light and slower-than-light wave nodes in commercial continuous wave (CW) lasers trace Lorentz-Minkowski space-time-wave coordinate manifolds. A reexamination of CW laser interference and wave velocity suggests a simple re-derivation of fundamental ideas of both special relativity and quantum theory. The result is a unified approach to quantum theory and relativity with improved physical clarity and simpler logic than either subject could have by itself.
Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 2.00 PM. All students are welcome! Refreshments will be served.
Wednesday, 24 July 2002, Room PS 147
3:00 PM | Sean Bailey | Low Temperature Photoluminescence of Hydrothermally and Czochralski grown Bi12GeO20 |
3:15 PM | Daniel Bergman | Growth Rates of Band Pattern Formation in a Rotating Suspension of Non-Brownian Settling Particles |
3:30 PM | Ryan Scott | Calculating Reaction Enthalpy Using Electronic Structure Analysis for the Addition of Ozone to Nitrogen Monoxide and Ozone to Ethylene |
3:45 PM | Jacob Weierman | Double-Wall Chiral Carbon Nano-Tubes |
4:00 PM | Darin Corman | Synthesis of 6-Mercaptopurine Riboside Capped CdTe Nanoparticles |
Thursday, 25 July 2002, Room PS 147
1:30 PM | David Klein | Preliminary Investigations Towards Developing an In-Situ Subsurface Radiation Monitor |
1:45 PM | Adam Wood | Some Optical Properties of Bismuth Titanium Oxide Alloy Crystals |
2:00 PM | Greg Bergesen | Stability Analysis for the Laser with Injected Signal |
2:15 PM | Byron Bemis | Design and Construction of a Rotating Sample Holder for an FTIR Spectrometer |
2:30 PM | Lucas Ward | XPS and UPS Spectra of Cyanogen Chloride Deposited on Silicon (100) |
Speaker: | Dr. Robert T. Sang |
Laser Atomic Physics Laboratory | |
Centre for Quantum Dynamics | |
Griffith University, Queensland, Australia | |
Date: | Thursday, July 25, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | The Manipulation of Nano-Bombs |
Rare gas metastable atoms are atoms in excited states that can not decay via single photon dipole transitions. As a consequence, the lifetime of the states are greatly increased. In the case of neon for example, the lifetime of the 3P2 metastable state is approximately 20s. Rare gas atoms in excited states have a great deal of internal energy which can be released with high efficiency when colliding with another atom or a surface. This usually results in an ionisation process and makes the detection efficiency of these atoms very high, hence they are an ideal species for many experiments in atomic physics. Furthermore, rare gas metastable atoms have optical transitions that allows for highly effective centre of mass manipulation using light. A disadvantage of experiments with these species of atoms, is that the production of high density beams of these species is difficult.
In this talk I will present an overview of the research that we are performing to enhance and manipulate beams of metastable atoms as well as applications such as investigations of cold collisions of these species and the utilisation of metastable atomic beams in nanotechnological applications.
No talks scheduled
Speaker: | Dr. John Sutherland |
Brookhaven National Laboratory, Upton, N.Y. | |
Date: | Thursday, August 8, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | Molecular Analysis of DNA damage: Physical Principles and Biomedical Applications |
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.
Speaker: | Dr. Allan Cheville |
School of Computer and Electrical Engineering | |
Oklahoma State University | |
Date: | Tuesday, August 13, 2002 |
Time: | 3:00 PM |
Place: | 102 ATRC |
Title: | Optics at the Low Frequency Edge-Grazing at the THz Table |
Since physical measurements in optics commonly deal with intensity, it is common to "ignore" the fact that light also has phase. To extract phase information, or to directly determine E rather than EE*, one must measure the phase relative to another light beam such as with interferometry or holography. New techniques based on ultrafast optics such as FROG, TADPOLE, SPIDER, and GRENOUILLIE also permit computational extraction of optical phase while simultaneously adding to the worlds' supply of acronyms. The direct measurement of E and phase is familiar to electrical engineers however, since electronic techniques permit measurements of these quantities out to tens of GHz.
This talk focuses on the region between optics and electronics--the terahertz or far infrared spectral region. There has been relatively little work done in this region since THz frequencies are difficult to access either from the electronics side (too fast) or from the optics side (lack of good sources and detectors). However, this frequency range permits both direct measurement of the electric field (electronics) and the use of free space propagation and quasi-optical techniques.
Here we present both an overview of how to access this spectral region through a union of ultrafast optics and microelectronic fabrication. Also, several examples of THz spectroscopy and imaging are presented, making use of unique properties of ultrafast single cycle pulses with directly measurable electric fields.
First Week of Classes
Speaker: | Dr. P.K. Kabir |
Department of Physics | |
University of Virginia | |
Date: | Thursday, August 29, 2002 |
Time: | 1:30 PM |
Place: | Willard Hall, Room 004, OSU |
& Bizzell Library, Room 104, OU | |
Title: | Time Reversal in K Systems |
Labor Day Week. No talks scheduled.
Speaker: | Dr. Doug Bergman |
Department of Physics and Astronomy10 | |
Rutgers University | |
Date: | Thursday, September 12, 2002 |
Time: | 1:30 PM |
Place: | Willard Hall, Room 004, OSU |
& Bizzell Library, Room 104, OU | |
Title: | HiRes |
Speaker: | Dr. Penger Tong |
Department of Physics | |
Oklahoma State University | |
Date: | Thursday, September 12, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | Plume Dynamics in Turbulent Heat Transport |
Non-equilibrium systems often organize into various interesting structures, just like the equilibrium systems do. An example is turbulent Rayleigh-Bénard convection, which has attracted much attention in recent years. Despite its relatively low Reynolds number (Re), turbulent convection shares many common features that are usually associated with high-Re turbulent flows. These features include coherent structures, intermittent fluctuations, and anomalous scaling. In this talk I will briefly review the recent development in the area and report our recent experimental studies of the dynamics of thermal plumes near the conducting surface and in the bulk region of the cell [1-3]. Using the techniques of laser Doppler velocimetry, thermometry, and flow visualization, we measure the large-scale flow structure and the local heat flux in a convection cell filled with water. The experiment clearly demonstrates how otherwise random unstable modes (thermal plumes) in a closed cell organize themselves in both space and time to generate a large-scale flow structure, which rotates and oscillates coherently in a turbulent environment.
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.
Speaker: | Beining Nie |
Department of Physics, OSU | |
Date: | Friday, September 13, 2002 |
Time: | 1:30 PM |
Place: | PS 147 |
Title: | Modeling of the Photocycle of Photoactive Yellow Protein |
Molecular dynamics simulation was applied to study the first two intermediate states--pG and pR during the photocycle of Photoactive Yellow Protein (PYP). Conformational changes of PYP in pG and pR states based on Gó-model parameters were investigated. By biasing to the native state, we solvated specific conformations of PYP intermediates with water box and trancated the solvated system in order to carry out quantum chemistry calculations of pKa shift before proton transfer and after proton transfer. With a large number of energy calculations of proton transfer event, the energy barrier for proton transfer will be obtained.
Speaker: | Dr. Rigoberto Advincula |
Department of Chemistry | |
University of Houston | |
Date: | Thursday, September 19, 2002 |
Time: | 3:30 PM |
Place: | PS 103 (Please Note!) |
Title: | Nanostructured Organic and Polymer Materials: |
From Ultrathin Film to Nanoparticles |
This talk gives an excellent overview of our efforts on the synthesis, characterization, and functionalization of organic and polymer materials as nanomaterials. The protocol follows the fourfold approach to materials research, which includes: synthesis, layer ordering, surface analysis, and application. A number of synthesis strategies usually involve the preparation of oligomers, amphiphiles, precursor polymers, and dendrimers. While conventional organic and polymer synthesis methodologies are utilized, the challenge is in a careful rationale and design incorporating the functional group (electro-optical properties) simultaneously with self-assembly parameters for nanostructuring. This protocol is demonstrated in a number of our current projects, which includes: the electrostatic layer-by-layer (LBL) self-assembly of oligothiophenes, the precursor-polymer and electrodeposition approach to pi-conjugated polymers, photoalignment of azobenzene dye dendrimers, and aggregation of oligothiophene dendrimers (organic nanoparticles). Another strategy involves the use of the surface initiated polymerization (SIP) approaches to tethering polymer brushes on a variety of flat and nanoparticle surfaces and nanocomposite preparation. Thus a number of targeted materials are realized based on this approach. This approach bridges an important gap between organic and polymer chemists and the materials needs in nanoscience and nanotechnology.
Note: Coffee and cookies in PS 117. This colloquium is hosted by the Chemistry Department.
Speaker: | Dr. Dirk M. Guldi |
Notre Dame Radiation Laboratory | |
University of Notre Dame | |
Date: | Friday, September 27, 2002 |
Time: | 2:30 PM |
Place: | PS 103 (Note: Unusual Time and Place) |
Title: | Carbon Nanostructures: From Fullerenes to Nanotubes. |
Their Implementation into Donor Acceptor Ensembles |
Combining the rapidly evolving fields of novel nanostructured materials and supramolecular chemistry is an attractive strategy for constructing large and complex, yet highly ordered, functioning molecular and supramolecular entities as viable tools for efficient conversion of solar energy. The fundamental advantage for the fabrication of tailored architectures is the control over composition, alignment, orientation and separation between individual constituents at a molecular level. In nanostructures, charge separation and retarding energy-wasting charge recombination depends, to a large extent, on the cooperativity of these key parameters. In this context, the ability of fullerenes to inhibit charge recombination, while still allowing fast charge separation, is of paramount importance. This renders fullerenes profitable electron acceptors or relays in donor-acceptor ensembles. Recent developments towards novel super- and supramolecular donor-acceptor nanoarchitectures will be highlighted. In particular, detailed photo-, photoelectro- and radiation-chemical studies in condensed media and organized thin films at semiconductor surfaces will be described to illustrate the performance of a model system in artificial photosynthesis.
Speaker: | Dr. Chung Kao |
Department of Physics and Astronomy | |
University of Oklahoma | |
Date: | Thursday, October 3, 2002 |
Time: | 1:30 PM |
Place: | Willard Hall, Room 004, OSU |
& Bizzell Library, Room 104, OU | |
Title: | Higgs Decays into Leptons |
Speaker: | Dr. Enver Bulur |
Department of Physics | |
Oklahoma State University | |
Date: | Thursday, October 3, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | Optically Stimulated Luminescence: |
Basics and Some Applications Related to Radiation Measurements |
Optically Stimulated luminescence (OSL) is the emission of light from a previously excited solid upon stimulation with light (usually visible photons). High-energy irradiation creates free electrons and holes in a crystal lattice, which are then trapped in the lattice defects (either pre-existing or created by radiation). Trapped charges are stable for a long enough time to allow storage. Upon optical stimulation trapped charges are released and may recombine radiatively resulting in the so-called Optically Stimulated Luminescence.
Initial work related to materials exhibiting OSL was concentrated on infrared detection. Nowadays main application areas are radiation dosimetry dating of geological and archaeological findings and two-dimensional imaging of radiation fields (photons and heavy particles like neutrons). Basic processes leading to Optically Stimulated Luminescence, experimental considerations, some applications in radiation dosimetry and imaging will be discussed briefly.
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.
Speaker: | Peyman Ahmadi |
Department of Physics, OSU | |
Date: | Friday, October 4, 2002 |
Time: | 1:30 PM |
Place: | PS 147 |
Title: | Laser Cooling and BEC |
Speaker: | Dr. Joe Lykken |
Theoretical Physics Department | |
Fermi National Accelerator Laboratory | |
Date: | Thursday, October 10, 2002 |
Time: | 1:30 PM |
Place: | Willard Hall, Room 004, OSU |
& Bizzell Library, Room 104, OU | |
Title: | CPT Violation and Neutrinos |
Speaker: | Dr. Joe Lykken |
Theoretical Physics Department | |
Fermi National Accelerator Laboratory | |
Date: | Thursday, October 10, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | Particle Accelerators for Cosmology |
From quarks we learn about cosmology, and from cosmology we learn about quarks. This colloquium addresses how this remarkable connection exists, and what we hope to learn from it in the next few years.
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.
Speaker: | Dr. Sourov Roy |
Department of Physics | |
Technion, Israel Institute of Technology | |
Date: | Tuesday, October 15, 2002 |
Time: | 12:30 PM |
Place: | PS 147 |
Title: | Anomaly Mediated Supersymmetry Breaking and Its Test in Linear Colliders |
Speaker: | Dr. Carl Bender |
Department of Physics | |
Washington University | |
Date: | Thursday, October 17, 2002 |
Time: | Postponed |
Speaker: | Dr. Eddie Baron |
Department of Physics and Astronomy | |
University of Oklahoma | |
Date: | Thursday, October 17, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | Using Supernovae as Cosmological Probes |
I describe the recent work that has been done using Type Ia Supernovae as cosmological beacons and the surprising discovery of the "dark energy" heretofore completely unknown, but it is the major energy component of our universe. I describe planned future observations with which I am involved and explain how Type II supernovae can also be used to provide a completely independent test for the existence of 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.
Speaker: | Prof. Hermann Kochan |
German Space Agency, Cologne, Germany | |
Date: | Monday, October 21, 2002 |
Time: | 11:30 AM |
Place: | Life Sciences East, Room 216 |
Title: | Planetary Simulations in the Laboratory: Recent Work and Future Ideas |
Broadcast live from the University of Arkansas
Speaker: | Dr. Kimball A. Milton |
Department of Physics and Astronomy | |
University of Oklahoma | |
Date: | Thursday, October 24, 2002 |
Time: | 1:30 PM |
Place: | Willard Hall, Room 004, OSU |
& Bizzell Library, Room 104, OU | |
Title: | Calculating Casimir Energies in Renormalizable Quantum Field Theory |
Speaker: | Dr. Qian Niu |
Department of Physics | |
University of Texas at Austin | |
Date: | Thursday, October 24, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | Picking Single Atoms From a Bose-Einstein Condensate |
In this talk, I will review the basics of Bose-Einstein condensation and single particle trapping. I will then describe a scheme for extracting atoms one by one from a condensate with high fidelity. The single atoms may be used for quantum information processing.
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.
Speaker: | Dr. William S. Burgett |
Department of Physics | |
University of Texas at Dallas, Richardson, TX | |
Date: | Thursday, October 31, 2002 |
Time: | 1:30 PM |
Place: | Willard Hall, Room 004, OSU |
& Bizzell Library, Room 104, OU | |
Title: | Trans-GZK Cosmic Rays: Is This New Physics? |
As has been widely reported and discussed, there apparently exists a flux of cosmic rays with energies exceeding the Greisen-Zatsepin-Kuzmin (GZK) threshold for proton propagation from source distances greater than ~ 50 - 100 Mpc.This poses a challenge as no (currently) obvious source appears to exist within this distance of the Earth. Thus, the "mystery of the highest energy cosmic rays" may signal the existence of physics beyond the Standard Model or the existence of as yet undetected cosmic accelerators with an unknown acceleration mechanism (or both!). This talk will provide a summary of what is known, not known, and still debatable about these events as well as the explanations proposed to resolve the puzzle. In particular, details will be given of one specific scenario known as "precocious unification of neutrinos" that arises as a low energy consequence of some higher-dimensional string models. Finally, a description will be given of how observational data can be used to set a lower limit on the string scale of these models.
Speaker: | Dr. Jacques H.H. Perk |
Department of Physics | |
Oklahoma State University | |
Date: | Thursday, October 31, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | Recent Progress in Susceptibility Calculations |
in Periodic and Quasiperiodic Ising Models |
A decades old surmise of Aharony and Fisher on corrections to scaling in the two-dimensional Ising model is finally shown to fail using record-long series expansions obtained by a novel polynomial algorithm. Various implications will be discussed.
The wavevector-dependent susceptibility (structure function) of a number of quasiperiodic lattices can also be computed using new polynomial algorithms. Regular lattices with quasiperiodic interactions varying by Fibonacci rules will be discussed first. A quasicrystal with Ising spins on half the sites of a Penrose tiling will be considered next. A number of conclusions will be drawn.
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.
Speaker: | Dr. Bruce J. Ackerson |
Department of Physics | |
Oklahoma State University | |
Date: | Wednesday, November 6, 2002 |
Time: | 3:30 PM |
Place: | Case Study 3, Student Union |
Title: | Hypothesis Based Learning |
Speaker: | Dr. Henry Kelly |
President | |
Federation of American Scientists | |
Date: | Thursday, November 7, 2002 |
Time: | 1:30 PM |
Place: | Willard Hall, Room 004, OSU |
& Bizzell Library, Room 104, OU | |
Title: | Getting Serious About Research in Learning |
Speaker: | Dr. Gary Yen |
School of Computer and Electrical Engineering | |
Oklahoma State University | |
Date: | Thursday, November 7, 2002 |
Time: | 4:00 PM |
Place: | PS 110 |
Title: | Evolutionary Multi-criterion Decision Making and Optimization |
This study classifies existing Multiobjective Evolutionary Algorithms (MOEAs) and analyzes several state-of-the-art MOEAs based on different design procedures of those crucial building blocks. A Rank-Density based Genetic Algorithm (RDGA) is designed by synergistically integrates important features of existing MOEAs in a unique way. From the simulation results, RDGA has shown its capability in finding a near-complete and near-optimal Pareto set at the final generation. In addition, an MOEA with dynamic population size---Dynamic Multiobjective Evolutionary Algorithm (DMOEA)---is derived from RDGA. Regulated by dynamic population strategies, DMOEA is found to be competitive with, or even superior to, other representative MOEAs in terms of keeping the diversity of the individuals along the trade-off surface, tending to extend the Pareto front to new areas, finding a well-approximated Pareto optimal front, and achieve optimal population size according to desired density value and approximated number of trade-off hyper-areas. Based on extensive studies on MOEAs, an MOEA Toolbox is designed to provide flexible choices to the users by combining different building blocks.
Note: Please note that we start half an hour later than usual.
Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.30 PM. All students are welcome! Refreshments will be served.
Speaker: | Dr. Martin Griebel |
Max-Planck-Institute for Solid-State, Stuttgart, Germany | |
Date: | Friday, November 8, 2002 |
Time: | 1:30 PM |
Place: | 102 ATRC |
Title: | Novel Materials for Ultrafast Photoconductive Switches: |
Superlattices of Self-Assembled ErAs-Islands in a III-V Semiconductor Matrix |
Semiconductor materials with ultrafast optical response allow a broad variety of high-frequency optoelectronic applications such as ultrabroad bandwith photodetectors, picosecond-sampling with photoconductive switches as well as detection and generation of terahertz radiation with photomixers and pulse driven dipolar antennas. Recent findings suggest that a material consisting of equidistant layers of self-assembled ErAs islands embedded in a GaAs matrix (ErAs:GaAs) is a promising alternative to low-temperature-grown GaAs, the most widely used material for these types of applications.
We study the carrier dynamics in ErAs:GaAs as a function of the superlattice period L with the help of photocurrent autocorrelation experiments. We observe an increase of the electron lifetime t by nearly two orders of magnitude from 190 fs to 17 ps if L is enlarged from 10 to 400 nm. This behavior is understood in terms of a diffusion model that predicts a quadratic dependence of t on L in agreement with the data.
Photoconductive sampling has been performed by embedding ErAs:GaAs-photoconductive switches in a coplanar waveguide structure. Illuminating the switches with subpicosecond laser pulses by means of dispersion compensated optical fibers we accomplished a time resolution of less than 2.0 ps. Cryogenic experiments revealed that this time resolution is temperature independent and insensitive to magnetic fields. In conjunction with the straightforward, unparalleled lifetime tunability, thermal stability, and availability of additional control parameters to influence the dark current of ErAs:GaAs, this material appears ideally suited to perform transport measurements on mesoscopic devices with ultrahigh time resolution under cryogenic conditions and in high magnetic fields, our ultimate longterm goal.
By narrowing the bandgap of the matrix material surrounding the ErAs island layers, photoconductive switches may be operated at longer wavelengths. Photocurrent autocorrelation experiments on an ErAs:InGaAs superlattice sample displayed electron lifetimes of 1.1 ps. Tuning the wavelength from 750 nm to 1 B5m revealed no change and we expect no difficulties in extending the operation-wavelengths up to 1.67 B5m.
Note: Opportunity to meet the speaker at 1:15 pm. D. Grischkowsky is the host. Phone 4-6622, email: grischd@ceat.okstate.edu.
Speaker: | Dr. Stuart A. Raby |
Department of Physics | |
Ohio State University | |
Date: | Thursday, November 14, 2002 |
Time: | 1:30 PM |
Place: | Willard Hall, Room 004, OSU |
& Bizzell Library, Room 104, OU | |
Title: | Higgs and SUSY Particle Predictions from SO(10) Yukawa Unification |
Speaker: | Dr. Stuart Raby |
Department of Physics | |
Ohio State University | |
Date: | Thursday, November 14, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | The Puzzle of Charge and Mass |
Beginning with the seminal work of Rutherford, Geiger and Marsden in 1911, physicists have investigated the atom using particle beams (alpha particles, and protons) as probes. They developed new detection methods; the geiger counter, scintillators, cloud and then bubble chambers. This new paradigm for probing matter and new detectors lead to many discoveries.
To make a long story short, by 1974 the chaos of discovery lead to the Standard Model describing all observed particle phenomena in terms of three fundamental forces (4 including gravity) and the fundamental building blocks of matter, quarks and leptons. Only now, after the dust of this chaotic discovery settles, are we able with hindsight to recognize the underlying principles which define the theory we call the Standard Model.
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.
Speaker: | Alexander Mitov |
Department of Physics | |
University of Rochester | |
Date: | Tuesday, November 19, 2002 |
Time: | 12:30 PM |
Place: | PS 147 |
Title: | Radion in the Randall-Sundrum Model |
Speaker: | Dr. Lynne H. Orr |
Department of Physics and Astronomy | |
University of Rochester | |
Date: | Thursday, November 21, 2002 |
Time: | 1:30 PM |
Place: | Willard Hall, Room 004, OSU |
& Bizzell Library, Room 104, OU | |
Title: | QCD and the Top Quark |
Speaker: | Dr. Eleanor Hodby |
JILA (Joint Institute for Laboratory Astrophysics) | |
& University of Colorado, Boulder, Colorado | |
Date: | Thursday, November 21, 2002 |
Time: | 3:30 PM |
Place: | PS 110 |
Title: | Superfluidity and Rotating BECs |
Realization of Bose-Einstein Condensation in a dilute, weakly-interacting atomic vapor has proved to be one of the most important achievements in Physics over the last decade. Bose-Einstein condensation occurs when many identical particles occupy the same quantum mechanical state. It is at the heart of phenomena such as superconductivity and superfluidity of liquid helium. This talk presents experimental evidence that such a dilute gas condensate is superfluid, by investigating its behavior in a rotating trapping potential. In particular, the observation of a purely irrotational flow pattern and the formation of quantized vortices will be described.
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.
Thanksgiving
Prefinals Week
Speaker: | Dr. Kam-Sing Wong |
(Ph.D. Oxford, 1987) | |
Associate Professor of Physics | |
Hong Kong University of Science and Technology | |
Date: | Monday, December 2, 2002 |
Time: | 3:30 PM |
Place: | ATRC 103 |
Title: | Ultrafast Dynamics of Random Lasers from ZnO Nano-Particles |
We investigated random scattering of light in a disorder gain medium of ZnO powder using the pump-probe technique. Using a probe beam at l=390nm, the width (q) of the coherent backscattering peak from the ZnO powder is measured to be ~7.5°, thus the coherent scattering length l is approximately 1.2l (q=l/2pl) which is close to the strong scattering regime. When a pump beam (l=267nm) exceeds a certain excitation threshold, laser-like supernarrow peaks (bandwidth less than 1nm) emerged from the ZnO broad photoluminescence background. Concurrently, we also observed enhancement and sharpening of the coherent backscattering cone. Since light from the center of the backscatter cone experience the largest number of scatterings (i.e. longest gain length), this result is thus consistent with the random laser model that the supernarrow peak is due to amplification and stimulated emission of photon in the random gain medium. The ultrafast risetime and picosecond decay time of the emission state above the lasing threshold show that the sharp emission peaks are indeed due to stimulated emission. These random laser dynamics are in good qualitative agreement with the recent theoretical simulations.
Note: Opportunity to meet the speaker at 3:15 pm. W. Zhang is the host. Phone: 4-7297, email: wwzhang@okstate.edu.
Speaker: | Dr. Robert M. Metzger |
Department of Chemistry & | |
Center for Materials for Information Technology | |
University of Alabama at Tuscaloosa | |
Date: | Thursday, December 5, 2002, 2002 |
Time: | 3:30 PM |
Place: | PS 103 |
Title: | Hexagonally Ordered Nanoporous Aluminum Oxide as a Casing |
for Magnetic Nanowires, Nanoholes, and Nanoditches |
Acid-anodized aluminum forms amorphous alumina with long and columnar nanopores with approximately hexagonal ordering ("alumite"). Excellent hexagonal ordering of these nanopores has been achieved by 24 hours of anodization [1], but with restricted domain size (2-4 µm2) [2], which can be increased to 100 µm2 with longer anodization [2].
We have electrodeposited Fe in disordered pores of 11 nm diameter [3], and Co in ordered pores 30 nm in diameter and 100 nm pore-to-pore separation: the magnetic easy axis is out-of-plane (the Co crystallographic c-axis in plane, oriented randomly) [2]. The longer wires have an easy axis out-of-plane, with squareness > 0.9, coercivity > 1900 Oe, and a fluctuation field of 5.3 Oe. The shorter wires are more isotropic, with lower coercivities (~ 1300 Oe) and larger fluctuation fields ~ 8.4 Oe.
Using a sinusoidal waveform, we can control the average length and diameter of these nanowires, but there is still a distribution of nanowire lengths. When we use an unusual AC voltage waveform, multiple nucleation of Co nanowires with c-axis out of plane is obtained [5,6].
Using Ar ion milling, we can make 10 nm nanoholes on the bottom of the alumite nanopores [7]. In addition, we can deposit atop a Si substrate some single-walled or multiple-walled carbon nanotubes, then cover them partially with a Ti layer thinner than the nanotubes, then sonicate the nanotubes away, leaving nanoditches [8].
Note: Refreshments at 3:00 p.m. in PS 117.
Speaker: | Dr. Paul W. Fenimore |
Los Alamos National Lab | |
Date: | Friday, December 6, 2002 |
Time: | 3:00 PM |
Place: | PS 108 |
Title: | Slaving: Solvent Fluctuations Dominate Protein Dynamics and Functions |
Protein motions are essential for function. Comparing protein processes with the dielectric fluctuations of the surrounding solvent shows that they fall into two classes: nonslaved and slaved. Nonslaved processes are independent of the solvent motions; their rates are determined by the protein conformation and vibrational dynamics. Slaved processes are tightly coupled to the solvent; their rates have approximately the same temperature dependence as the rate of the solvent fluctuations, but they are smaller. Because the temperature dependence is determined by the activation enthalpy, whereas the protein and the hydration shell control the activation entropy through the energy landscape. Bond formation is the prototype of nonslaved processes; opening and closing of channels are quintessential slaved motions. The prevalence of slaved motions highlights the importance of the environment in cells and membranes for the functions of proteins.
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This page was prepared by Helen Au-Yang and Jacques H.H. Perk.
jhhp@jperk.phy.okstate.edu