Seminars and Colloquia, January through June, 2003

• This Week's schedule.
• Earlier Semesters.
• Typical Week's schedule.
• January 1-3, 2003's schedule.
• January 6-10, 2003's schedule.
• January 13-17, 2003's schedule.
• January 20-24, 2003's schedule.
• January 27-31, 2003's schedule.
• February 3-7, 2003's schedule.
• February 10-14, 2003's schedule.
• February 17-21, 2003's schedule.
• February 24-28, 2003's schedule.
• March 3-7, 2003's schedule.
• March 10-14, 2003's schedule.
• March 17-21, 2003's schedule.
• March 24-28, 2003's schedule.
• March 31-April 4, 2003's schedule.
• April 7-11, 2003's schedule.
• April 14-18, 2003's schedule.
• April 21-25, 2003's schedule.
• April 28-May 2, 2003's schedule.
• May 5-9, 2003's schedule.
• May 12-16, 2003's schedule.
• May 19-23, 2003's schedule.
• May 26-30, 2003's schedule.
• June 2-6, 2003's schedule.
• June 9-13, 2003's schedule.
• June 16-20, 2003's schedule.
• June 23-27, 2003's schedule.
• June 30-July 4, 2003's schedule.

Seminars and Colloquia, Typical Week:

Center for Laser and Photonics Research Seminar:

Center for Sensors & Sensor Technologies Seminar:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

OSU NanoNet Seminar:

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

Oklahoma State Physics Department

Seminars and Colloquia, January 1-3, 2003

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, January 6-10, 2003

No talks scheduled: Prelim Exams

Oklahoma State Physics Department

Seminars and Colloquia, January 13-17, 2003

No talks scheduled: First Week of Classes

Oklahoma State Physics Department

Seminars and Colloquia, January 20-24, 2003

OSU NanoNet Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, January 27-31, 2003

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

Unusual ability of carbon is to form zero dimensional (0D) quantum dots of subnanometer dimension in the form of fullerenes and one-dimensional (1D) quantum wires in the form of carbon nanotubes. Buckminsterfullerene, C₆₀, has become one of the most attractive nanostructured materials as 0D quantum dots due to the structural perfection and reproducibility, availability in large quantities, self-assembled nanostructure, and monodisperse feature. The current research focuses on the ultrafast and nonlinear optical processes possibly affected by the introduction of tungsten into C₆₀. Sol gel films doped with fullerene-tungsten complex are prepared using the pulsed laser deposition (PLD) technique. Significant enhancement of optical nonlinearity is experimentally observed using the eclipsing Z-Scan technique. Unique linear and nonlinear optical properties for metal-C₆₀ complex are mainly attributed to highly polarizable conjugated -electron delocalized over the surface of the carbon cage. We demonstrate upconverted luminescence that provides the proof of the higher excited state absorption responsible for reverse saturable absorption. Four-wave mixing measurement indicates that the fullerene-tungsten complex shows a fast nonlinear response of 10 ps. Large optical nonlinearity and fast nonlinear response make metal fullerenes be attractive candidates for optical limiting 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.

Oklahoma State Physics Department

Seminars and Colloquia, February 3-7, 2003

Special High Energy Physics Seminar:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Joint Oklahoma NanoNet, Chemistry & Physics Colloquium:

Note: Refreshments at 3:00 p.m. in PS 117.

OSU NanoNet Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, February 10-14, 2003

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

The effect of molecular properties on the conductivity of molecular-scale electronic components is well studied. The back-effect of the current on the molecule can likewise be substantial. In particular, resonance inelastic current can leave sufficient energy in molecular modes for dynamic processes such as vibration or chemical reaction to ensue.

A representative example, which is the current-triggered vibration of C₆₀ trapped between two gold electrodes will be discussed. The unoccupied molecular orbitals of C₆₀ assist in the conduction of electrons between the gold electrodes. However, the equilibrium displacement of ionic C₆₀^- is closer to the gold surface than that of neutral C₆₀. Thus during the tunneling event, part of the electronic energy will be channeled into vibrational excitations of the C₆₀ center of mass. The details of the quantum mechanical study of this process will be outlined in this talk.

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:

First meeting is two weeks from now.

Oklahoma State Physics Department

Seminars and Colloquia, February 17-21, 2003

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

Do the Great Red Spot of Jupiter, spirals in a frog egg, and ripples on sand have anything in common? The sizes are vastly different, and the biology of even a simple frog egg is vastly more complicated than the physics of sand or a fluid. Does an understanding of these ordered spatial patterns require a detailed understanding at the molecular level of the system in which the pattern is formed? We argue not. Rather, we show that patterns formed in diverse systems can in many cases be understood from a common approach. Ordered spatial patterns emerge when a system is stressed sufficiently by imposing a difference in temperature, velocity, chemical concentration, etc. across the system. Suppose, for example, a temperature difference is imposed on a box of gas by heating from below and cooling from above. For small temperature differences the heat simply flows from the bottom to the top, but for a temperature difference above a certain well-defined level, an ordered striped pattern (convection rolls) spontaneously develops. The general principles that govern the formation of these patterns and many others in physics, chemistry, and biology will be discussed and illustrated.

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.

OSU NanoNet Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, February 24-28, 2003

Physics Colloquium:

Abstract:

According to the scaling theory of localization, all quantum electronic states are localized in two-dimensional (2D) systems. One consequence of the theory is that there is no quantum percolation transition in 2D. However, in a real system at a finite temperature, electron phase coherent length is finite and the system is between quantum and classical. We find, in such a 2D system, a metal-insulator transition (MIT) caused by a novel type of semi-classical percolation. The relevance to recently observed 2D MIT 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:

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

Special High Energy Physics Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, March 3-7, 2003

APS March Meeting

Oklahoma High Energy Physics Seminar on Talk-Back Television:

OSU NanoNet Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, March 10-14, 2003

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Postponed

Physics Colloquium:

Abstract:

New aluminum oxide crystals for volumetric optical data storage will be presented for the first time. Magnesium impurity and double oxygen vacancy defects are responsible for the main optical properties of the new material. One-bit recording in multiple layers was successfully demonstrated using two-photon absorption while one-photon absorption and a confocal fluorescence detection scheme were applied for binary and multilevel data readout. Holographic recording was also demonstrated. Plane holograms were recorded and were read non-destructively. Optical disks with capacity of up to 1 TB and high data transfer rate can be developed.

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

Journal Club on Statistical Mechanics and Condensed Matter Physics:

Postponed

Oklahoma State Physics Department

Seminars and Colloquia, March 17-21, 2003

Spring Break

Oklahoma State Physics Department

Seminars and Colloquia, March 24-28, 2003

Photonics Seminar:

Note: Attendance of both IGERT Fellows and Photonics students is mandatory.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

A 'shallow donor,' consisting of an electron bound to an impurity atom in a semiconducting material, exhibits a hydrogen-atom-like character. Modern crystal growth techniques, such as molecular beam epitaxy, allow realization of shallow donor configurations where the electron and the donor atom are spatially separate, despite being bound together by their mutual coulomb interaction, as in case of technologically important High-Electron Mobility Transistors. Here we report results of far-infrared (FIR) magneto-spectroscopy of such 'remote shallow donor' states in Si-doped GaAs/AlGaAs quantum well structures. The shallow donor transitions, induced by FIR radiation in the presence of a magnetic field, are studied by means of photoconductivity, a tool that has so far remained unexplored in remote donor identification despite its success in bulk donor identification. Unlike previous investigations, no doping is performed in regions where electrons are confined, thereby promoting formation of only remote donor species. A variety of shallow donor transitions are observed, including those corresponding to binding of in-well electrons to Si dimmers in the barrier. Experimental results are compared with theoretical calculations based on a variational approach within the effective mass theory. Apart from underlining the significance of donor segregation in heterostructures, our results also indicate that, in contrast to prior belief, impurity incorporation into the host crystal may have a non-random origin.

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.

OSU NanoNet Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, March 31-April 4, 2003

Physics Colloquium:

Abstract:

We re-examine the interpretation and significance of the classical extinction theorem by adopting a microscopic point of view to several relevant problems. The usual interpretation of the extinction theorem as given by Ewald states that a wave incident on a crystal (or dielectric) is extinguished by dipoles in the boundary of the medium and is replaced by a wave consistent with Maxwell's equations for the medium. We show that the extinction theorem can be described as a mathematical identity only, with little physical significance. To further prove our point, a microscopic approach is taken to the problem of a monochromatic plane wave normally incident on a dielectric. We assume the medium to be made up of polarizable molecules. We sum over ALL the dipoles of the medium and obtain the usual results. The dipoles at the boundary are shown to have no significant role when plane waves are treated. Further work using pulses is required for timing results... how long does it take light to reflect? (fs or sub-fs) and how to measure this? These questions 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.

Oklahoma State Physics Department

Seminars and Colloquia, April 7-11, 2003

Special Physics Colloquium:

Abstract:

Users, in particular, of commercial quantum-chemical computer codes such as Gaussian98 have embraced density-functional theory (DFT). As implemented in all such codes, DFT calculations require accurate 3-D numerical integration. Thus one should expect and/or demand that those codes switch from using Gaussian basis functions to using completely numerical methods, such as those used by Becke in his NUMOL academic code. This talk looks at the alternative, completely analytic DFT methods. The analytic approach to molecular physics is reviewed beginning with the linear-combination-of-atomic-orbitals (LCAO) approximation and the use of Gaussian orbitals. In the LCAO approach basis functions necessarily have angular momentum. That fact has consequences for analytic integral evaluation. It is likely that the most efficient computerized analytic integral evaluation will involve generalized Gaunt coefficients [BI Dunlap, J. Chem. Phys. 118, 1036 (2003)]. Rapid analytic integral evaluation facilitates analytic approaches to DFT, which are based on variational fitting. Analytic Xα, in which every atom has an individual exchange-correlation energy, is reviewed because it is the most robust such method developed to date.

Supported by the Office of Naval Research directly and through the Naval Research Laboratory.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Joint Chemistry, Physics and Oklahoma NanoNet Colloquium:

Abstract:

When a quantum charged particle moves along a closed trajectory in the external magnetic field, the Aharonov-Bohm effect can occur, caused by quantum interference between paths with different phases. We propose a novel magnetic interference effect for a neutral, but polarizable exciton in a quantum ring. The ground state of polarized exciton acquires a nonzero angular momentum with increasing normal magnetic field. This leads to the suppression of the photoluminescence in defined windows of the magnetic field. Such 'blinking' behavior comes from magnetic quantum phases and allows us to tailor optical properties of nanocrystals. We demonstrate theoretically this effect using models of InAs self-organized quantum rings and type-II quantum dots. In relatively shallow nano-structures, the quantum dot can be ionized due to optically-induced Auger processes. In the presence of Auger processes, the emission spectra exhibit very spectacular behavior coming from exciton ionization.

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 14-18, 2003

Photonics Seminar:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

The early demonstration of dispersion management by the use of additional laser fields and the realization of electromagnetically induced transparency have led to the emergence of a new discipline of optical physics namely the subject of coherent control of optical properties of a variety of systems. Many varied applications of coherent control have been proposed and realized. These include predictions like enhancement of nonlinearly generated signals, enhancement of magneto-optical rotations, laser induced large chirality, sub and super-luminal propagation, two photon transparency, quenching of spontaneous emission etc. The underlying physical principles and the role of quantum interferences in coherent control would 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.

OSU NanoNet Seminar:

Abstract:

Nanostructured materials can be defined as materials in which the grain size or layer thickness is in the range of 1-100 nm, much smaller than that found in conventional materials. They are both scientifically interesting and technologically important and have started a revolution in materials science. Superior properties have been demonstrated for a broad range of nanomaterials including materials whose strengths approach theoretical limits, ceramics and intermetallics that possess ductility, and materials with enhanced magnetic, electronic and optical properties. Potential applications for nanostructured materials include paint pigments, cosmetics, pharmaceuticals, medical diagnostics, catalysts and supports, membranes and filters, batteries and fuel cells, electronic, magnetic and optical devices, flat panel displays, biomaterials, structural materials, and protective coatings. A major effort of Professor Apblett's research group is to develop new chemical methods for the economical production of nanostructured metal oxides for use in catalyst, magnetic, and environmental applications. The use of such materials for in situ neutralization of terrorist explosives will also be discussed.

Oklahoma State Physics Department

Seminars and Colloquia, April 21-25, 2003

College of Engineering, Architecture and Technology Southwest Mechanics Lecture Series:

Abstract:

Large scale motions having streamwise extent of the order of the thickness of the turbulent flow, delta, and scaling with the outer variable are known to contain a large fraction of the streamwise turbulent kinetic energy. But, they are not thought to contribute very much to the Reynolds shear stress--hence Townsend's (1976) designation of delta-scale motions as "inactive". PIV experiments show that, contrary to conventional wisdom, the delta-scale modes make a substantial contribution to the total shear stress. Studies of Reynolds shear stress co-spectra reveal two clearly separated modes, one consisting of the delta-scale modes and the inertial subrange, and the other consisting of super-delta scales, i.e. scales much longer than the boundary thickness.

Ronald J. Adrian was educated at the University of Minnesota (B.M.E. 1967, M.S. 1969) and at Churchill College, Cambridge, where he received his Ph.D. degree in physics in 1972. He is a member of the Department of Theoretical and Applied Mechanics at the University of Illinois, Urbana-Champaign where he holds the Hoeft Chair in Engineering and is the Director of the Laboratory for Turbulence and Complex Flow. His research interests are the space-time structure of turbulent fluid motion and the development of techniques, both experimental and mathematical, to explore this structure. Methods to which he has made fundamental contributions are the laser Doppler velocimeter technique, the method of particle image velocimetery and the stochastic estimation method. He co-edited Experiments in Fluids, and a ten volume series on Laser Techniques in Fluid Mechanics, and currently, he serves as an Associate Editor of the Journal of Fluid Mechanics. His awards have included two SAE Colwell Merit Awards, a U.S. Churchill Foundation Award, and the Nusselt-Reynolds Prize. He is a past Chairman of the American Physical Society Division of Fluid Dynamics, and the US National Committee on Theoretical and Applied Mechanics. He is a Fellow of the American Physical Society, the American Academy of Mechanics and ASME, and he is a member of the United States National Academy of Engineering.

Contact Person: Prof. Frank W. Chambers, Mechanical and Aerospace Engineering, fchamb@ceat.okstate.edu.

Photonics Seminar:

Note: Attendance of both IGERT Fellows and Photonics students is mandatory.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

I will talk about statistical properties--level spacing distribution, level correlations, etc.--of the energy levels with large quantum numbers (semiclasical quantization) in size-quantized systems. Correspondence between the properties of classical motion and the quantum energy spectrum will be discussed. In a particular, I will show that the familiar spectrum of a particle in a rectangular box reveals some very surprising features. The level of my presentation should be accessible to undergraduate physics majors.

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.

Special Computational Physics Seminar:

Journal Club on Statistical Mechanics and Condensed Matter Physics:

Postponed in view of much activity earlier this week

Oklahoma State Physics Department

Seminars and Colloquia, April 28-May 2, 2003

Oklahoma NSF EPSCoR Annual Conference:

Meeting Date is May 15. Registration Deadline is 5:00 PM, May 1. There is no cost to register, but space is limited. To register or for more information, see the meeting website.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

The Higgs mechanism is responsible for the generation of mass in the Standard Model. The shortcomings of the Higgs in the Standard Model are reviewed. The Standard Model Higgs boson could be discovered at the Tevatron or the LHC.

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.

Prefinals Week

No Friday talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, May 5-9, 2003

Finals Week

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, May 12-16, 2003

Oklahoma NSF EPSCoR Annual Conference:

Network for Nanostructured Materials & Functional Genomics Resources Consortium

Registration Deadline is 5:00 PM, May 1. There is no cost to register, but space is limited. For more information, see the meeting website.

Oklahoma State Physics Department

Seminars and Colloquia, May 19-23, 2003

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, May 26-30, 2003

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, June 2-6, 2003

Oklahoma State Physics Department

Seminars and Colloquia, June 9-13, 2003

No talks scheduled.

Oklahoma State Physics Department

Seminars and Colloquia, June 16-20, 2003

Special Seminar:

Abstract:

Certain quasiperiodic sequences introduced by the famous mathematician N. G. de Bruijn are examined; a theorem of Tracy on the Fibonacci sequence can be more easily proven and is generalized to other sequences, including the silver-mean sequence. The Penrose Tiling construction from the pentagrid of de Bruijn is reviewed. We show how Kronecker's theorem can be used to calculate the probability and joint probability of meshes in the pentagrid.

Using these results, the q-dependent susceptibility in a number of quasiperiodic Ising models are evaluated. The q-dependent susceptibility is the Fourier transform of the pair-correlation function and is equivalent to the diffraction patterns in scattering experiments.

Oklahoma State Physics Department

Seminars and Colloquia, June 23-27, 2003

Oklahoma State Physics Department

Seminars and Colloquia, June 30-July 4, 2003

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