Atomic, Molecular and Optical Physics Commons^™

Atomic Data Revisions For Transitions Relevant To Observations Of Interstellar, Circumgalactic, And Intergalactic Matter, Frances H. Cashman, Varsha P. Kulkarni, Romas Kisielius, Gary J. Ferland, Pavel Bogdanovich

Physics and Astronomy Faculty Publications

Measurements of element abundances in galaxies from astrophysical spectroscopy depend sensitively on the atomic data used. With the goal of making the latest atomic data accessible to the community, we present a compilation of selected atomic data for resonant absorption lines at wavelengths longward of 911.753 Å (the H I Lyman limit), for key heavy elements (heavier than atomic number 5) of astrophysical interest. In particular, we focus on the transitions of those ions that have been observed in the Milky Way interstellar medium (ISM), the circumgalactic medium (CGM) of the Milky Way and/or other galaxies, and the intergalactic medium …

Building And Validating A Model For Investigating The Dynamics Of Isolated Water Molecules, Grant Cates

Senior Theses

Understanding how water molecules behave in isolation is vital to understand many fundamental processes in nature. To that end, scientists have begun studying crystals in which single water molecules become trapped in regularly occurring cavities in the crystal structure. As part of that investigation, numerical models used to investigate the dynamics of isolated water molecules are sought to help bolster our fundamental understanding of how these systems behave. To that end, the efficacy of three computational methods—the Euler Method, the Euler-Aspel Method and the Beeman Method—is compared using a newly defined parameter, called the predictive stability coefficient ρ. This …

Continuity Of Heavy Rydberg Behaviour In The Ungerade Ion-Pair States Of H2, Alexander M. Chartrand, Robert J. Donovan, Kenneth P. Lawley, Elizabeth Mccormack

Physics Faculty Research and Scholarship

Heavy Rydberg behaviour and absolute quantum defects are reported for resonances in the ungerade manifold of H₂ above the (1s, 3l) dissociation limit. The continuity of the vibrational progression of the B''B-bar state through the crossing with the 3p asymptote is demonstrated and a predominantly diabatic picture of the vibrational motion emerges, indicating that the ion-pair resonances possess little 6¹Σ_u⁺ state character.

Time-Resolved Thz Conductivity Of An Intermediate Band Semiconductor, Elliot Weiss

Macalester Journal of Physics and Astronomy

Intermediate band materials have promising applications as affordable, highly efficient solar materials. However, intermediate band solar cells exhibit low efficiency to date. Carrier recombination is a critical process that limits efficiency. If electrons relax to the valence band before they can be collected, their energy is lost. To help understand the recombination dynamics and physical properties of intermediate band semiconductors, we obtain time-resolved THz conductivity measurements of the intermediate band semiconductor, GaPAsN, at various temperatures. From our results, we build a model that provides insight to the recombination dynamics of GaPAsN.

Intervalley Scattering Rates In Tellurium Observed Via Time-Resolved Terahertz Spectroscopy, Joshua R. Rollag

Macalester Journal of Physics and Astronomy

We conducted time-resolved terahertz spectroscopy measurements on the elemental semiconductor tellurium. Pump-probe measurements were used to find the conductivity as a function of time in single crystalline tellurium samples. It was found that the excitation dynamics in tellurium changes for photon energies of 1.03 eV and 1.55 eV. The change in these excitation dynamics was attributed to intervalley scattering effects. A model using intervalley scattering and Auger recombination was fit to the data, giving a value of 2.28 ps for the intervalley scattering time constant in tellurium.

Conductivity Measurements Of A Thermoelectric Nanomaterial Through Thz Spectroscopy, Michaela S. Koller, James Heyman, Gunnar Footh

Macalester Journal of Physics and Astronomy

In today’s society there is a great demand on energy output—in the United States alone we rely heavily on non-renewable energy sources. Thermoelectric materials may be able to be used to create more efficient energy systems or recover wasted heat from inefficient technologies. This paper focuses on the conductivity of a new thermoelectric material that incorporates copper into a tellurium nanowire PEDOT:PSS material. The addition of copper seems to increase the conductivity of the material, although the exact relationship between the percentage of copper to tellurium and its affect on the conductivity is uncertain from the results.

Quasi-Optical Measurement For Low Loss Material Characterization In Submillimeter Wave Range, Ha Khiem Tran, Thanh Ngoc Dan Le, Branimir Pejcinovic

Student Research Symposium

An accurate knowledge of dielectric constant of materials is required in many sub-millimeter wave applications. Free-space measurement of materials has always been one of the first choices due to their non-destructive nature and relatively simple sample preparation. However, free-space measurement systems at sub-millimeter frequency range suffer from two main problems: high loss because of divergent beam pattern and diffraction when the beam waist of the radiated beam is relatively large compared to the size of the sample under tests. In order to mitigate these issues, we set up a quasi-optical system using off-axis parabolic mirrors, which enhance the dynamic range …

Discontinuities In The Electromagnetic Fields Of Vortex Beams In The Complex Source-Sink Model, Andrew Vikartofsky, Liang-Wen Pi, Anthony F. Starace

Anthony F. Starace Publications

An analytical discontinuity is reported in what was thought to be the discontinuity-free exact nonparaxial vortex beam phasor obtained within the complex source-sink model. This discontinuity appears for all odd values of the orbital angular momentum mode. Such discontinuities in the phasor lead to nonphysical discontinuities in the real electromagnetic field components. We identify the source of the discontinuities, and provide graphical evidence of the discontinuous real electric fields for the first and third orbital angular momentum modes. A simple means of avoiding these discontinuities is presented.

Developing Tools For A Precision Measurement Of Newton's Gravitational Constant Using Atom Interferometry, Elizabeth Ashwood

Honors College Theses

We propose a new atom interferometry scheme for making a precision measurement of Newton's Gravitational constant (Big G) using NASA's Cold-Atom Laboratory which is scheduled to be deployed to the International Space Station in 2017. The proposed interferometer consists of splitting a harmonically confined Bose-Einstein condensate into multiple pieces. In a perfect harmonic potential, all of the pieces come to rest at the same time, at which point the harmonic trap is turned off. These initially motionless condensate clouds then accumulate different phases due to the relative velocity they develop caused by the gravitational attraction of a nearby source mass. …

Kinetic Theory Of Dark Solitons With Tunable Friction, Hilary M. Hurst, Dimitry K. Efimkin, I. B. Spielman, Victor Galitski

Faculty Research, Scholarly, and Creative Activity

We study controllable friction in a system consisting of a dark soliton in a one-dimensional Bose-Einstein condensate coupled to a non-interacting Fermi gas. The fermions act as impurity atoms, not part of the original condensate, that scatter off of the soliton. We study semi-classical dynamics of the dark soliton, a particle-like object with negative mass, and calculate its friction coefficient. Surprisingly, it depends periodically on the ratio of interspecies (impurity-condensate) to intraspecies (condensate-condensate) interaction strengths. By tuning this ratio, one can access a regime where the friction coefficient vanishes. We develop a general theory of stochastic dynamics for negative mass …

Studies In Mesoscopics And Quantum Microscopies, Zhenghao Ding, Gabriel C. Spalding

Honors Projects

This thesis begins with a foundational section on quantum optics. The single-photon detectors used in the first chapter were obtained through the Advanced Laboratory Physics Association (ALPhA), which brokered reduced cost for educational use, and the aim of the single-photon work presented in Chapter 1 is to develop modules for use in Illinois Wesleyan's instructional labs beyond the first year of university. Along with the American Association of Physics Teachers, ALPhA encourages capstone-level work, such as Chapter 1 of this honors thesis, which is explicitly designed to play the role of passing on, to a next generation of physics majors, …

Silver Nanoparticles As A Potential Solar Absorber, Benjamin Hardy

Honors Projects

This work reports the development of Silver nanoparticles implanted into a polymer as a solar absorber. The plasmonic nature of silver nanoparticle allows for adjustments to be made in its UV-VIS-NIR absorbance spectrum. A combination of different sized/shaped particles could result in ideal absorption of the majority of the solar spectrum. Allotting this with the stability of a polymer leads to potential solids or solutions that could work as a solar absorber. Tests were also performed to determine whether or not UV-C irradiation during synthesis effects the characteristics of silver nanoparticles, in particular the absorbance. Successful synthesis of silver nanoparticle …

High Current Table-Top Setup For Femtosecond Gas Electron Diffraction, Omid Zandi, Kyle J. Wilkin, Martin Centurion

Martin Centurion Publications

We have constructed an experimental setup for gas phase electron diffraction with femtosecond resolution and a high average beam current. While gas electron diffraction has been successful at determining molecular structures, it has been a challenge to reach femtosecond resolution while maintaining sufficient beam current to retrieve structures with high spatial resolution. The main challenges are the Coulomb force that leads to broadening of the electron pulses and the temporal blurring that results from the velocity mismatch between the laser and electron pulses as they traverse the sample. We present here a device that uses pulse compression to overcome the …

Microwave Assisted Dipole-Dipole Transitions, Jacob T. Paul

Physics and Astronomy Honors Papers

We explore this two photon assisted transition through computational and numerical analysis of possible energy levels. We calculate the matrix elements of the energy transition in detail discussing constants and the quantum mechanical possibilities of energy exchanges in these systems.

The goal is to better understand the energy exchange, so that moving forward we can control it. This paper covers the theoretical ends to controlling the energy transition by the way of two photon assisted transitions. The energy transitions take place between a dipole-dipole interaction, and a microwave photon.

Using An Atomic Molecular Optics Laboratory For Undergraduate Research And Mentoring Of Physics Students In Georgia, Matthew P. Dallas

Georgia College Student Research Events

Using an Atomic Molecular Optics Laboratory for Undergraduate Research and Mentoring of Physics Students in Georgia

An Atomic and Molecular Optical (AMO) Physics research lab is an excellent tool to train and mentor undergraduate students in advanced laboratory techniques. Students gain valuable basic experience in experimental designs, data acquisition techniques, working with high precision optical equipment, building electronics, and working in the machine shop. The current project is building and testing an enclosure for the diode laser to reduce sound and vibrational interference. In addition, we are developing and evaluating a new, more compact laser cavity which is 3d printed. …

Stochastic Electron Acceleration In Lightning Flashes, Samer Alnussrat

Research Horizons Day Posters

No abstract provided.

Neutron-Unbound Excited States Of 23n, M. Jones, T. Baumann, J. Brett, J. Bullaro, P. A. Deyoung, J.E. Finck, N. Frank, K. Hammerton, J. Hinnefeld, Z. Kohley, A. N. Kuchera, J. Pereira, A. Rabeh, J. K. Smith, A. Spyrou, Sharon L. Stephenson, K. Stiefel, M. Tuttle-Timm, R. G.T. Zegers, M. Thoennessen

Physics and Astronomy Faculty Publications

Neutron unbound states in 23N were populated via proton knockout from an 83.4 MeV/nucleon 24O beam on a liquid deuterium target. The two-body decay energy displays two peaks at E1∼100keV and E2∼1MeV with respect to the neutron separation energy. The data are consistent with shell model calculations predicting resonances at excitation energies of ∼3.6MeV and ∼4.5MeV. The selectivity of the reaction implies that these states correspond to the first and second 3/2− states. The energy of the first state is about 1.3 MeV lower than the first excited 2+ in 24O. This decrease is largely due to coupling with the …

Lorentz-Symmetry Test At Planck-Scale Suppression With Nucleons In A Spin-Polarized 133 Cs Cold Atom Clock, H. Pihan-Le Bars, C. Guerlin, R.-D. Lasseri, J.-P. Ebran, Q. G. Bailey, S. Bize, E. Khan, P. Wolf

Publications

The authors introduce an improved model that links the frequency of the 133 Cs hyperfine Zeeman transitions.

Atomic Layer Growth Of Inse And Sb₂Se₃ Layered Semiconductors And Their Heterostructure, Robert Browning, Neal Kuperman, Bill Moon, Raj Solanki

Physics Faculty Publications and Presentations

Metal chalcogenides based on the C–M–M–C (C = chalcogen, M = metal) structure possess several attractive properties that can be utilized in both electrical and optical devices. We have shown that specular, large area films of ^_y-InSe and Sb₂Se₃ can be grown via atomic layer deposition (ALD) at relatively low temperatures. Optical (absorption, Raman), crystalline (X-ray diffraction), and composition (XPS) properties of these films have been measured and compared to those reported for exfoliated films and have been found to be similar. Heterostructures composed of a layer of y-InSe (intrinsically n-type) followed by a layer of …

Implementation And Characterization Of A Magneto-Optical Trap, Michael Anthony Highman

Undergraduate Honors Thesis Projects

Rydberg atoms are those which have their valence electron excited to high principal quantum number n. Atoms in the Rydberg state are the research focus of the experiment from which this paper derives. Rydberg atoms are fragile, and thermal collisions are enough to ionize and destroy the Rydberg state. A magneto-optical trap (MOT) serves the purpose of "ultra-cooling" atoms to temperatures around 140 micro-Kelvin and dramatically reduces the impact of thermal collisions. This paper details the theory and equipment necessary to realize a MOT of rubidium-85. It will then discuss the characterization of the MOT we implemented by a …