Seminars and Colloquia, July through December, 2019

• This Week's schedule.
• Earlier Semesters.
• Typical Week's schedule.
• July 1-5, 2019's schedule.
• July 8-12, 2019's schedule.
• July 15-19, 2019's schedule.
• July 22-26, 2019's schedule.
• July 29-August 2, 2019's schedule.
• August 5-9, 2019's schedule.
• August 12-16, 2019's schedule.
• August 19-23, 2019's schedule.
• August 26-30, 2019's schedule.
• September 2-6, 2019's schedule.
• September 9-13, 2019's schedule.
• September 16-20, 2019's schedule.
• September 23-27, 2019's schedule.
• September 30-October 4, 2019's schedule.
• October 7-11, 2019's schedule.
• October 14-18, 2019's schedule.
• October 21-25, 2019's schedule.
• October 28-November 1, 2019's schedule.
• November 4-8, 2019's schedule.
• November 11-15, 2019's schedule.
• November 18-22, 2019's schedule.
• November 25-29, 2019's schedule.
• December 2-6, 2019's schedule.
• December 9-13, 2019's schedule.
• December 16-20, 2019's schedule.
• December 23-27, 2019's schedule.
• December 30-31, 2019's schedule.

Seminars and Colloquia, Typical Week:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

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

Oklahoma State Physics Department

Seminars and Colloquia, July 1-5, 2019

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, July 8-12, 2019

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, July 15-19, 2019

Physics Colloquium:

Abstract:

Space is a harsh environment for human explorers. Ionizing radiation occurs naturally in space, and can have detrimental effects on both the spacecraft hardware and the health of the astronaut crew.

This presentation provides an overview of the space ionizing radiation environment, NASA radiation measurements and instrumentation, models and tools used for radiation exposure predictions, space weather forecasting needs for long duration exploration missions, and exposure risks and mitigation with a focus on crew health. The particularities are discussed of the environmental components and the implications on risk assessments and spacecraft shielding efficiency.

NASA’s Exploration Program aims to return astronauts to the Moon by 2024. The Orion spacecraft is the first Exploration architecture element, and the first NASA human spacecraft to include design requirements for crew radiation protection. Orion is designed by Lockheed Martin as prime contractor. Its maiden flight Exploration Flight Test 1 (EFT-1) was successfully completed in 2014. The trajectory exposed the spacecraft to the core of the Van Allen proton belts. This provided an opportunity for validating the radiation shielding predictions by measurements. The results indicated good correlation with pre-flight predictions. Orion’s next test flight Artemis 1, formerly known as Exploration Mission 1 (EM-1) is scheduled for 2020. The 21-42 day mission to cis-lunar space provided the opportunity for a large scale international radiation experiment referred to as the Matroshka AstroRad Radiation Experiment (MARE). MARE consists of two radiotherapy phantoms—named Zohar and Helga—located in the Orion seats #3 and #4, and fitted with an extensive complement of passive and active radiation detectors. Zohar is also fitted with AstroRad—a novel individual astronaut radiation shield manufactured by StemRad Israel. This allows simultaneous characterization of the intravehicular radiation environment and mitigation efficiency. NASA, the German Aerospace Center DLR, and the Israeli Space Agency ISA are the co-principal investigators to MARE. The co-investigator team consists of dosimeter providers from 10 countries on 3 continents, and includes the Department of Physics at OSU. Lockheed Martin facilitates MARE by as payload integrator and liaison to the Orion Program on behalf of the international science team.

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, July 22-26, 2019

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, July 29-August 2, 2019

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, August 5-9, 2019

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, August 12-16, 2019

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, August 19-23, 2019

First week of classes

Physics Journal Club, special event:

Abstract:

Unique physical properties and atomic structure of real impact diamonds from Popigai astrobleme (Yakutia, North-East Russia) and exotic closed-shell multiply twinned graphite microcrystals found in Chelyabinsk superbolide dust (Feb 15, 2013, Ural mountains, Northern Russia) were studied using ab initio DFT and MD simulations. The key features of unique atomic structure and mechanical properties of the carbon nano- and microcrystals extracted from real impact and meteorite materials were interpreted using electronic structure calculations. The unique scale and dramatic consequences of both historic events for dinosaur existence and human history makes a theoretical consideration of the carbon nanostructures critically important for survival of entire humanity.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Oklahoma State Physics Department

Seminars and Colloquia, August 26-30, 2019

Second week of classes.

Department of Chemistry Seminar:

Abstract:

The optical properties of gold and silver nanoparticles have been known for centuries, appearing in Roman glassware as well as medieval stained glass. An understanding of the phenomenon giving rise to these brilliant colors emerged in the last century: collective oscillations of conduction electrons called localized surface plasmon resonances (LSPRs) can be excited by light, leading to wavelength-dependent absorption and scattering. LSPRs have a broad technology potential as an attractive platform for surface-enhanced spectroscopies, non-bleaching labels, hyperthermal cancer therapy, waveguides, and so on. Excitingly, this light-matter interaction can be controlled by the size, shape, and dielectric environment of the nanoparticles; enabling the manipulation of LSPR energy, absorption/scattering ratio, light confinement, as well as far-field and near-field emission geometry, all important for specific applications.

Most plasmonic metals studied to date are composed of either Cu, Ag, and Au. The former two can pose significant challenges related to oxidation, the latter is often perceived as cost-prohibitive, and all three are rare. Recently, much attention has been focused on earth-abundant Al, which is an excellent plasmonic in the UV. This talk will briefly discuss colloidal Al nanoparticles as a plasmonic material, then report results on a new composition: magnesium. Mg nanoparticles are remarkably active plasmonics across the UV, Vis and NIR, as shown optically and with STEM-EELS. Surprisingly, they are stable in air for weeks owing to a self-limiting oxide layer. Colloidal Mg has potential on its own as a plasmonic structure, and can also be used as a scaffold for additional surface chemistry, sensing, and hybrid photocatalysts.

Oklahoma State Physics Department

Seminars and Colloquia, September 2-6, 2019

Labor Day holiday: Monday, September 2.

Condensed Matter Seminar:

Abstract:

The first part of the talk is about numerical calculations of the remnant magnetization of non-interacting fine magnetic particles, assuming a Gamma distribution of relaxation times. In addition, a log-normal of distribution of energy barriers have been carried out with different means and standard deviations for three systems.

The second part of the talk is about the time-dependent magnetization measurements on three systems of Fe₃O₄ fine particles. The remnant magnetization measurements were carried out in the temperature range T = 5 - 300 K over a period of time (t) between 30 - 300 s. The remnant magnetization was found to obey the relation M = C − S ln t. Annealing the sample at 530 K was found to increase its magnetic anisotropy constant. The results were analyzed within the context of Néel theory of magnetic clusters.

Oklahoma State Physics Department

Seminars and Colloquia, September 9-13, 2019

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Oklahoma State Physics Department

Seminars and Colloquia, September 16-20, 2019

Chemistry and Physics Colloquium:

Abstract:

Our group targets preparation, single crystal growth, computational studies, and characterization of low-cost hybrid organic-inorganic and all-inorganic halides for prospective optoelectronic applications. In this general talk, I will overview the rich structural chemistry, physical properties and prospective applications of several brand-new hybrid organic-inorganic and all-inorganic halide materials. The unprecedented control over structural dimensionality, distortions and tunable chemical compositions allows for fine-tuning of physical properties of halides including their optical band gaps, transport and magnetic properties. In our group, lessons learned from literature are applied to a expand the halides family beyond Pb/Sn-based perovskites. The bird’s eye view will be concluded by our group’s recent results on (mostly) non-perovskite halides, which demonstrate ultrabright room-temperature luminescence with quantum yield values approaching unity.

Note: Refreshments served in PS 147 at 3:00 PM.

Oklahoma State Physics Department

Seminars and Colloquia, September 23-27, 2019

Oklahoma State Physics Department

Seminars and Colloquia, September 30-October 4, 2019

Physics Colloquium:

Abstract:

NASA recently selected the Dragonfly quadcopter, on which I serve as Deputy Principal Investigator, as the fourth mission in its New Frontiers program of planetary missions.  Dragonfly will land on the surface of Saturn’s hazy moon Titan to explore prebiotic chemistry, to evaluate its habitability, and look for chemical biosignatures.  Titan is one of just 4 planetary bodies that has both a thick atmosphere and a solid surface—Venus, Earth, and Mars are the others.  Among these, only Titan and Earth have active hydrological cycles with clouds, rain, and surface lakes and seas, though Titan’s contain methane and ethane instead of water.  I will discuss the present state of our knowledge about Titan’s geology, chemistry, and meteorology, as well as discussion the Dragonfly mission and how it will answer outstanding questions.  (1) How far has prebiotic chemistry progressed toward life? (2) What potentially habitable biomes might Titan possess, both with respect to water-based life and methane/ethane-based “life, but not as we know it”? And (3) is there chemical evidence for past or extant life on Titan?

Note: Reception in 147 Physical Sciences at 3:00 PM. Traditional student-speakeri chat. Open to the public! Refreshments served.

Oklahoma State Physics Department

Seminars and Colloquia, October 7-11, 2019

Physics Colloquium:

Abstract:

Many processes in nature are driven by the conversion of light into chemical and mechanical energy at the level of single molecules. After absorbing a photon, chemical bonds can be broken and new bonds made, the structure of the molecule changes, and the extra energy appears in the form of vibrations (heat). These processes often take place on femtosecond timescales, and are thus hard to observe. In this talk, I will describe recent advances in our ability to capture these changes as they happen, on the relevant timescales and with atomic spatial resolution using ultrafast electron diffraction. We will focus on a few exemplary reactions were we have imaged the motion of nuclear wave-packets during bond breaking and structural changes, and coherent vibrations that persist in the ground state of the reaction products.

Note: Reception in 147 Physical Sciences at 3:00 PM. Traditional student-speaker chat. Open to the public! Refreshments served.

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

Condensed Matter Seminar:

Abstract:

Technological and scientific advancement has been driven by mankind’s ability to craft the world around us into functional technologies. In this talk, we will explore a modern method that continues this tradition, allowing the creation artificial crystalline structures of complex oxides with unprecedented properties that promise next generation functionalities. Pulsed laser deposition allows stacking of single atomic layers of disparate materials with sharp interfaces where novel properties, not present in either constituent materials, arise. To directly probe these nanoscale interfaces, advanced synchrotron X-ray characterization will be introduced as a powerful tool for investigating the strongly entangled lattice, orbital, charge, and magnetic degrees of freedom exhibited by these artificial structures. Some of the fascinating physical phenomena derived from these strongly correlated systems, such as unconventional superconductivity and 2D magnetism, will be showcased. We will conclude this talk with a discussion of the promising future applications for this class of materials, with an emphasis on topological phenomena.

Oklahoma State Physics Department

Seminars and Colloquia, October 14-18, 2019

Physics Colloquium:

Abstract:

Interference plays vital roles in both the fundamental and applicational aspects of physics. We will discuss the significance of interference for quantum mechanics. We will also point out how it opens up new directions of research in the fields of imaging and quantum information science. Finally, future research directions will be outlined for prospective graduate and undergraduate research students.

Note: Reception in 147 Physical Sciences at 3:00 PM. Traditional student-speaker chat. Open to the public! Refreshments served.

Oklahoma State Physics Department

Seminars and Colloquia, October 21-25, 2019

Fall Break: No classes Friday, October 25.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Abstract:

In this talk I will show how to probe a leptonic scalar which couples exclusively to the active neutrino at the LHC. Such a scalar can be produced at hadron colliders like LHC via vector boson fusion process and lead to same-sign dilepton, two forward jets and missing transverse energy. If the scalar mass is below GeV-scale, its couplings to neutrinos are stringently constrained by the low-energy high-precision data such as those from charged meson and charged lepton decays, W and Z data, neutrino beam experiments like MINOS, light dark matter searches in NA64, and IceCube limits on neutrino self-interactions. When the scalar mass is above the GeV-scale, the projected LHC sensitivity would surpass all existing bounds.

Oklahoma State Physics Department

Seminars and Colloquia, October 28-November 1, 2019

Physics Colloquium:

Abstract:

Join Scarlett Ruppert, Coordinator of Employee Wellness, to learn about the multitude of fitness and wellness programs and services offered to OSU students, faculty, staff and family members. Discover the variety of options available to you right here on campus and learn how to live a healthier, happier, more productive life,

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Abstract:

We examine the discovery potential for double Higgs production at the high luminosity LHC in the final state with two b-tagged jets, two leptons and missing transverse momentum. Although this dilepton final state has been considered a difficult channel due to the large backgrounds, we argue that it is possible to obtain sizable signal significance, by adopting a deep learning framework making full use of the relevant kinematics along with the jet images from the Higgs decay. The proposed method can be easily generalized to the semi-leptonic channel of double Higgs production, as well as to other processes with similar final states.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Oklahoma State Physics Department

Seminars and Colloquia, November 4-8, 2019

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Abstract:

In this talk I will entertain the possibility that the low energy excess observed by the MiniBooNE experiment is related to the mechanism of neutrino masses. I will review the MiniBooNE excess itself, present our proposal for a low scale neutrino mass model, and then show how these two could be connected.

Physics Colloquium:

Abstract:

Neutrinos are one of the most abundant of all known particles in the universe, but yet the least understood ones. A rich neutrino physics program is underway, in the US and abroad, with the goal of significantly improving our knowledge of this sector. In this colloquium I will revisit what sort of physics we expect to learn from neutrinos, and the challenges that we will need to overcome in order to do so. I will highlight the big questions in neutrino physics and the impact of future experiments in answering these.

Note: Reception in 147 Physical Sciences at 3:00 PM. Traditional student-speaker chat. Open to the public! Refreshments served.

Oklahoma State Physics Department

Seminars and Colloquia, November 11-15, 2019

Physics Colloquium:

Abstract:

The wave functions of electronic states in solids typically respect the symmetries of the host material. However, interactions among electrons can give rise to more exotic ordered ground states. An intriguing example is the formation of nematic electron fluids, whose wave functions spontaneously break the rotational symmetry of the underlying crystal lattice. In this talk, I will describe scanning tunneling microscope measurements of nematic order in bismuth surface states at high magnetic field. Spectroscopy reveals the emergence of broken symmetry quantum Hall states, and by imaging the corresponding anisotropic wave functions, we are able to directly visualize local nematic domains in this material.

Note: Reception in 147 Physical Sciences at 3:00 PM. Traditional student-speaker chat. Open to the public! Refreshments served.

Physics Journal Club:

Abstract:

In this talk, I will present a series of scanning tunneling microscope experiments that further investigate the role of electron-electron interactions and their tunability on the surface of bismuth. By changing the applied magnetic field, we can tune between two exotic quantum Hall states: a nematic phase with broken rotational symmetry and a ferroelectric phase in which the wave functions carry a dipole moment. Moreover, at boundaries between different nematic domains, we observe counter-propagating quantum Hall edge states. We are able to control the number of edge modes at the domain walls and thereby switch between metallic and insulating behavior in this new type of interacting Luttinger liquid.

Oklahoma State Physics Department

Seminars and Colloquia, November 18-22, 2019

Physics Colloquium:

Abstract:

Using conjugated organic materials for photovoltaics has many potential advantages over traditional inorganic semiconducting materials. Organic semiconductors are mechanically flexible, endlessly tunable through modification of the molecular constituents, and compatible with inexpensive and scalable processing methods. One application of organic electronic materials is organic photovoltaics (OPV), so-called plastic solar cells. OPV power conversion efficiency recently has risen to over 17% in lab-scale solar cells, and applications ranging from solar windows to roll-out solar panels are currently on the market or in development. In this talk I give an overview of the chemistry and physics underlying OPV performance and I describe an approach to modeling semiconducting polymer materials based on combining quantum mechanical calculations with large-scale classical molecular dynamics simulations. I present results derived using this approach to predict how charges move in six molecularly similar polymer OPV materials. The simulation results demonstrate that seemingly minor alterations in molecular structure can result in large changes in the bulk material, and that the interplay between the material structure and the underlying molecular properties can lead to surprising and counter-intuitive effects on material performance.

Note: Reception in 147 Physical Sciences at 3:00 PM. Traditional student-speaker chat. Open to the public! Refreshments served.

Department of Chemistry Seminar:

Abstract:

Molecular nanocars are single molecules with wheels, chassis, axles and light activated motors. The nanocars are so small that 50,000 could be parked across the diameter of a human hair. These have been studied as they drive across surfaces, and used to win the first international nanocar race, traveling 150 nm in 90 minutes around two pylons and across a finish line. The motors are now used in medicine for the killing of cells by drilling through their cell membranes or cell walls. Targeting is done with short peptides. Experiments on cancer cells and highly antibiotic resistant bacteria have been conducted.

Note: Refreshments will be served in PS 107 at 9:00am.

Physics Journal Club:

Abstract:

The paradigm for creating materials for energy applications is no longer simply discovering a single material but instead involves combining multiple materials to achieve a desired functionality. Simulating interfaces between disparate materials, or entire devices, requires large systems, often approximated by classical simulations based on force fields (FFs). The accuracy of such simulations can be questionable, however, because standard FFs may not accurately reflect forces in changing chemical environments near an interface or a defect. Moreover, in principle even seemingly small changes in how atoms are arranged may shift charges around or induce local polarizations via vibronic coupling in ways that would affect predicted material properties. We have observed such an effect in ab initio molecular dynamics simulations on inorganic perovskite materials of the form CsBX₃ (B = Sn,Pb, X = Br,I), which are of interest as possible absorbers for photovoltaics. We found that even small changes in the local environment around each atom can alter the atoms&srquo; properties in ways that standard FFs cannot capture. This is surprising because the simulated systems are nominally homogeneous materials with no defects, and yet the results imply that the atoms in these materials are electronically variable in ways that deserve attention when thinking about how to use the materials. To enable simulation of such materials, I describe a machine learning (ML) approach to predict quantum-derived atomic properties (e.g., charge, dipole moment, etc.) from descriptors of the local environment, and I conclude by outlining a general approach for incorporating the ML predictions into FFs for classical simulations.

Oklahoma State Physics Department

Seminars and Colloquia, November 25-29, 2019

Thanksgiving

Students’ Thanksgiving break, November 27-29.

Oklahoma State Physics Department

Seminars and Colloquia, December 2-6, 2019

Prefinals Week

Physics Colloquium:

Abstract:

TBA

Note: Reception in 147 Physical Sciences at 3:00 PM. Traditional student-speaker chat. Open to the public! Refreshments served.

Oklahoma State Physics Department

Seminars and Colloquia, December 9-13, 2019

Finals Week

Oklahoma State Physics Department

Seminars and Colloquia, December 16-20, 2019

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, December 23-27, 2019

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, December 30-31, 2019

No talks scheduled

Last Updated:

perk@okstate.edu