Apr 28, 2016
The Near-IR Spectrum of NO(X ̃<sup>2</sup>Π)-He Detected Through Excitation Into the A-State Continuum
Guest: Volker Beutner, UGA Physics and Astronomy
Thursday, April 28, 2016 10:00 am - 11:00 am
Location: Room 204B, Physics BuildingNitric Oxide (NO) plays an important role in areas such as Chemistry, Physics and Biology. In order to better understand the interactions of NO, its van der Waals complexes are the target of experimental and theoretical studies. Different NO-Rare gas complexes have been studied, however there has yet to be a report of any structured spectrum of the NO-He complex. In this thesis, a measurement of the near IR spectrum of NO-He in the region of the first NO overtone transition is presented. The IR absorption is detected by exciting the vibrationally excited complex into the A ̃-state continuum. The comparison to the theory of Klos, Chalasinski et al. (J. Chem. Phys. 112, 2195 (2000)) is in good agreement with the observed spectrum. Given the results, this thesis opens up the possibility of using Helium as a seed gas in order to study other NO van der Waals complexes. Dr. Mather now serves as Senior Project Scientist (95-present) for the James Webb Space Telescope, the successor to the great Hubble Space Telescope.
Apr 28, 2016
Guest: Dr. Ashvin Chhabra, President, Euclidean Capital
Thursday, April 28, 2016 3:30 pm
Location: Physics Auditorium (Rm 202)
The great crash of 2008 brought the question of stability of the financial markets to the forefront. Are financial markets stable? Was the great crash of 2008 an unexpected aberration? How should individual investors invest over a lifetime? Why are otherwise smart people such lousy investors? What does Modern Portfolio Theory tell us about investing and where does it fail? Does Behavioral finance capture Investor mistakes correctly? The speaker will attempt to answer these questions from a Physicist’s viewpoint. This leads to a new framework for investing that extends modern portfolio theory to incorporate large deviations – such as bubble and crashes. The Colloquium will not assume prior knowledge of the subject matter and will be aimed at an audience of a variety of backgrounds.
Ashvin B. Chhabra is President of Euclidean Capital and manages the Endowment for the Simons Foundation. He was Chief Investment Officer of Merrill Lynch Wealth Management, one of the largest wealth management firms in the world, from 2013-2015 and Chief Investment Officer for the Institute for Advanced Study, Princeton prior to that. He is the author of the recently published book The Aspirational Investor. Dr. Chhabra received his M.S. in Physics from the University of Georgia and Ph.D. from Yale University in Applied Physics.
Observatory Open House
Apr 28, 2016
Guest: Dr. Robin Shelton and Dr. Loris Magnani, UGA Physics and Astronomy
Thursday, April 28, 2016 9:30 pm - 10:30 pm
Location: UGA Observatory (4th floor Physics Building)
Our second public viewing with the newly fixed telescope will be on April 28, 2016. Because of the limited space in the dome, you must have a reservation to come to this showing. Click here to make a reservation.
The observatory is located at the top of the Physics building. To get to the observatory take the elevator to the 4th floor. A guide will meet you on the 4th floor and direct your group to the stairway that leads to the observatory. As the weather can be unpredictable, we might not know whether a viewing will be possible until shortly before the event begins.
If you need more information please call 706-542-2485.
May 20, 2016
Friday, May 20, 2016 1:30 pm - Saturday, May 21 1:00 pm
Location: CSP Conference Room (322)
Standard time-dependent and time-independent computational approaches have seen tremendous success in their application to reactive and inelastic chemical process. However, their utility is generally restricted to small numbers of atoms, low levels of internal excitation, and/or reduced spatial dimensionality. While advances in computational resources continue, the dynamical treatment of systems involving seven or so atoms is generally intractable without severe approximations for manifold reasons.
This one-day workshop brings together experts pursing other paradigms for chemical dynamics focused on three main themes: new algorithms and computing platforms (neural networks, machine learning, quantum simulation), alternative theoretical methodologies (quantum-semiclassical, kinetic theories), and nonstandard mechanisms and effects (roaming, geometric phase, external field control).
The meeting will roughly run from 1:30pm Friday to 1:00pm Saturday, with a poster session Friday evening. Participation will be limited to ~30 attendees and there is no registration fee. Inquires can be addressed to Phillip Stancil (email@example.com).
Details and schedule for the workshop, as well as registration can be accessed through the workshop site: https://www.physast.uga.edu/workshops/amqcd
Jun 24, 2016
Guest: Mayuri Perera, UGA Physics and Astronomy
Friday, June 24, 2016 1:00 pm - 2:00 pm
Location: Room 204B, Physics Building
The relaxation dynamics of Ce3+ ions in phosphor materials relevant to solid state lighting has been investigated. Of particular interest was the temperature dependence of the emission efficiency in heavily doped yttrium aluminum garnet (YAG) materials, which show a decreased quenching temperature compared to low concentration samples. Using site se- lective spectroscopy, we demonstrate that the lowering of the quenching temperature in high concentration samples is due to cerium ions in distorted sites. Our results can be generalized that high concentrations of cerium and/or an addition of optically mute rare earth ions to broaden the emission spectrum will lead to a lowered quenching temperature. We studied also Na2Gd2O(BO3)2 doped with Ce3+, a system where Ce3+ ions occupy two distinct lattice sites. In this case it is shown that the luminescence quenching is due to photoionization.
Index words: Lifetime Measurements, Luminescencence, Level Crossing, Rare Earth Ions, Photoionization
Jul 13, 2016
Guest: Renata Cumbee, UGA Physics and Astronomy
Wednesday, July 13, 2016 2:00 pm - 3:00 pm
Location: Room 322, Physics Building
Atomic collisions play a fundamental role in astrophysics, plasma physics, and fusion physics. In this dissertation, we focus on charge exchange (CX) between hot ions and neutral atoms relevant to a selection of astronomical environments. Even though charge exchange calculations can provide vital information including neutral and ion density distributions, ion temperatures, elemental abundances, and ion charge state distributions in the environments considered, both theoretical calculations and laboratory studies of these processes lack the necessary reliability and/or coverage. In order to better understand the spectra we observe in astrophysical environments in which both hot plasma and neutral gas are present, includ- ing comets, the heliosphere, supernova remnants, galaxy clusters, star forming galaxies, the outflows of starburst galaxies, and cooling flows of hot gas in the intracluster medium, a thorough CX X-ray model is needed. Included in this model should be a complete set of X-ray line ratios for relevant ion and neutral interactions for a range of energies.
In this work, theoretical charge exchange emission spectra are produced using cross sec- tions calculated with widely applied approaches including the quantum mechanical molecular orbital close coupling (QMOCC), atomic orbital close coupling (AOCC), classical trajectory Monte Carlo (CTMC), and the multichannel Landau-Zener (MCLZ) methods. When possible, theoretical data are benchmarked to experiments. Using a comprehensible, but still far from complete, CX database, new models are performed for a variety of X-ray emitting environments. In an attempt to describe the excess emission in X-rays of the starburst galaxy M82, Ne X CX line ratios are compared to line ratios observed in the region. A more com- plete XSPEC X-ray emission model is produced for H-like and He-like C-Al ions colliding with H and He for a range of energies; 200, 300, 500, 700, 1000, 2000, 3000, and 5000 eV/u. This model is applied to the northeast rim of the Cygnus Loop supernova remnant in an attempt to determine the contribution of CX to that region. The database is also applied to a preliminary model of the fast and slow solar wind interacting with the heliosphere.
Index words: atomic processes, galaxies: individual: M82, galaxies: starbursts, ISM: supernova remnants, line: formation, X-rays: general, X-rays: ISM, X-rays: galaxies
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