A System For Conducting Laser-Induced Fluorescence Measurements On Gas Mixtures Exposed To Alpha Radiation,
2018
University of Southern Mississippi
A System For Conducting Laser-Induced Fluorescence Measurements On Gas Mixtures Exposed To Alpha Radiation, Patrick Ables
Master's Theses
This paper documents modifications to an existing vacuum system to allow laser-induced fluorescence spectroscopy measurements within simulated atmospheres under a variety of conditions. This added capability will expand the laboratory’s ability to experimentally validate a computational model that calculates the effects of radiation within the atmosphere. The computational model could reveal radiation-induced chemical products that can be used to develop an alternative detection method that can be implemented from a safe distance. The selection of molecules for experimental validation has been limited to those which can be detected utilizing cavity ringdown spectroscopy. The current model indicates nitric oxide and ozone …
Compensation Of Non-Linear Bandwidth Broadening By Laser Chirping In Thomson Sources,
2018
Old Dominion University
Compensation Of Non-Linear Bandwidth Broadening By Laser Chirping In Thomson Sources, C. Maroli, V. Petrillo, I. Drebot, L, Serafini, B. Terzić, G. A. Krafft
Physics Faculty Publications
A new laser chirping prescription is derived by means of the phase-stationary method for an inci- dent Gaussian laser pulse in conjunction with a Li enard-Wiechert calculation of the scattered radia- tion flux and spectral brilliance. This particularly efficient laser chirp has been obtained using the electric field of the laser and for electrons and radiation on axis. The frequency modulation is some- what reduced with respect to that proposed in the previous literature, allowing the application of this procedure to lasers with larger values of the parameter a0. Numerical calculations have been performed using mildly focused and …
Weak Measurements For Quantum Characterization And Control,
2018
University of New Mexico
Weak Measurements For Quantum Characterization And Control, Jonathan A. Gross
Physics & Astronomy ETDs
This dissertation concerns itself with the virtues and vices of weak measurements. Weak measurements are all around us, but this does not mean that one should manufacture weakness on all occasions. We critically evaluate two proposals that claim weak measurements provide a novel means of performing quantum state tomography, allegedly increasing tomographic efficacy and yielding foundational insights into the nature of quantum mechanics. We find weak measurements are not an essential ingredient for most of their advertised features. In contrast to this negative finding, we highlight an optimal tomographic scheme for which weak continuous measurements are the best known implementation, …
Detecting Rydberg Interactions With Controlled Ionization,
2018
Ursinus College
Detecting Rydberg Interactions With Controlled Ionization, Lauren Yoast
Physics and Astronomy Summer Fellows
Rydberg atoms, which have a highly excited outer electron, are easily manipulated by electric fields. Using a magneto-optical trap, we cool Rubidium atoms to a few hundred millionths of a Kelvin above absolute zero and then excite to Rydberg states. Our first project looks at the dipole-dipole interactions of two atoms starting in the 33p state and ending in the 34s and 33s states. The standard technique is to apply an increasing electric field that ionizes the Rydberg electron and sends it to a detector, but unfortunately the signals overlap. A genetic algorithm is used to separate the signals by …
Imaging Cf3I Conical Intersection And Photodissociation Dynamics With Ultrafast Electron Diffraction,
2018
SLAC National Accelerator Laboratory, Menlo Park, CA
Imaging Cf3I Conical Intersection And Photodissociation Dynamics With Ultrafast Electron Diffraction, Jie Yang, Xiaolei Zhu, Thomas J.A. Wolf, Zheng Li, J. Pedro F. Nunes, Ryan Coffee, James P. Cryan, Markus Gühr, Kareem Hegazy, Tony F. Heinz, Keith Jobe, Renkai Li, Xiaozhe Shen, Theodore Veccione, Stephen Weathersby, Kyle J. Wilkin, Charles Yoneda, Qiang Zheng, Todd J. Martinez, Martin Centurion, Xijie Wang
Martin Centurion Publications
Conical intersections play a critical role in excited-state dynamics of polyatomic molecules because they govern the reaction pathways of many nonadiabatic processes. However, ultrafast probes have lacked sufficient spatial resolution to image wave-packet trajectories through these intersections directly. Here, we present the simultaneous experimental characterization of one-photon and two-photon excitation channels in isolated CF3I molecules using ultrafast gas-phase electron diffraction. In the two-photon channel, we have mapped out the real-space trajectories of a coherent nuclear wave packet, which bifurcates onto two potential energy surfaces when passing through a conical intersection. In the one-photon channel, we have resolved excitation …
Molecular Assembly Of Monolayer-Protected Gold Nanoparticles And Their Chemical, Thermal, And Ultrasonic Stabilities,
2018
Western Kentucky University
Molecular Assembly Of Monolayer-Protected Gold Nanoparticles And Their Chemical, Thermal, And Ultrasonic Stabilities, Steven Ray Isaacs
Masters Theses & Specialist Projects
Gold monolayer-protected nanoclusters (MPCs) with average diameters of 1-5 nm protected by alkane- and arenethiolates were synthesized. Mixed-monolayer protected nanoparticles (MMPCs) were prepared by functionalizing hexanethiolate-protected MPCs with either 11-mercaptoundecanoic acid (MUA-MMPC), 11-mercaptoundecanol (MUO-MMPC), or 4-aminothiophenol (ATP-MMPC) using ligand place exchange. Presentation of various chemical reagents such as nucleophile, acid, or base and change in physical environment through ultrasonic and thermal irradiation resulted in changes to particles and their physical properties. Thermogravimetric analysis (TGA) was used to measure maximum temperature of the derivated thermogravimetric peaks (Tmax,DTG) as a means of comparing temperature dependence of mass loss. The absorption spectrum within …
Fabrication Of An Apparatus For All-Optical Production Of Metastable Krypton,
2018
Old Dominion University
Fabrication Of An Apparatus For All-Optical Production Of Metastable Krypton, Lindsay M. Thornton
Physics Theses & Dissertations
Atom Trap Trace Analysis (ATTA) has made radiokrypton dating of polar ice and groundwater samples a possibility for scientists all over the world, allowing them to date samples further back in time and more accurately than other methods. However, this technique is hampered by the 36-hour cleaning process required for production of metastable-state krypton atoms via a radio-frequency driven plasma. Production of metastable krypton all-optically would dramatically increase the rate at which samples could be measured. Attempts to build an apparatus that could accomplish this have been done in the past but were lacking in aordability and practicality for widespread …
The Development Of A Diffraction Grating For An Element Of Directional Output Of Radiation From Microlasers,
2018
Lyceum Physical Technical High School
The Development Of A Diffraction Grating For An Element Of Directional Output Of Radiation From Microlasers, Evgenii Levdik
The International Student Science Fair 2018
In nanophotonics, axisymmetric microlasers became widespread. As they have lots of advantages, they can be used in many scientific and industrial areas, such as microchips for data transfer in order to make electrical circuits smaller. But there is a drawback: they radiate in all directions in the plane of the substrate. This is why elements of directional output of radiation are being developed. A necessary part of such element is the diffraction grating applied to the surface of the waveguide. Such gratings are already being created, but with very expensive methods, for example, electronic lithography. We present a technique for …
Control Of Harmonic Generation By The Time Delay Between Two-Color, Bicircular Few-Cycle Mid-Ir Laser Pulses,
2018
Voronezh State University, Russia
Control Of Harmonic Generation By The Time Delay Between Two-Color, Bicircular Few-Cycle Mid-Ir Laser Pulses, M. V. Frolov, N. L. Manakov, A. A. Minina, N. V. Vvedenskii, A. A. Silaev, M. Yu. Ivanov, Anthony F. Starace
Anthony F. Starace Publications
We study control of high-order harmonic generation (HHG) driven by time-delayed, few-cycle ω and 2ω counterrotating mid-IR pulses. Our numerical and analytical study shows that the time delay between the two-color pulses allows control of the harmonic positions, both those allowed by angular momentum conservation and those seemingly forbidden by it. Moreover, the helicity of any particular harmonic is tunable from left to right circular without changing the driving pulse helicity. The highest HHG yield occurs for a time delay comparable to the fundamental period T = 2π/ω.
The Development Of A Diffraction Grating For An Element Of Directional Output Of Radiation From Microlasers,
2018
Lyceum Physical Technical High School
The Development Of A Diffraction Grating For An Element Of Directional Output Of Radiation From Microlasers, Evgenii Levdik
The International Student Science Fair 2018
In nanophotonics, axisymmetric microlasers became widespread. As they have lots of advantages, they can be used in many scientific and industrial areas, such as microchips for data transfer in order to make electrical circuits smaller. But there is a drawback: they radiate in all directions in the plane of the substrate. This is why elements of directional output of radiation are being developed. A necessary part of such element is the diffraction grating applied to the surface of the waveguide. Such gratings are already being created, but with very expensive methods, for example, electronic lithography. We present a technique for …
Imaging The Three-Dimensional Orientation And Rotational Mobility Of Fluorescent Emitters Using The Tri-Spot Point Spread Function,
2018
Washington University in St Louis
Imaging The Three-Dimensional Orientation And Rotational Mobility Of Fluorescent Emitters Using The Tri-Spot Point Spread Function, Oumeng Zhang, Jin Lu, Tianben Ding, Matthew D. Lew
Electrical & Systems Engineering Publications and Presentations
Fluorescence photons emitted by single molecules contain rich information regarding their rotational motions, but adapting single-molecule localization microscopy (SMLM) to measure their orientations and rotational mobilities with high precision remains a challenge. Inspired by dipole radiation patterns, we design and implement a Tri-spot point spread function (PSF) that simultaneously measures the three-dimensional orientation and the rotational mobility of dipole-like emitters across a large field of view. We show that the orientation measurements done using the Tri-spot PSF are sufficiently accurate to correct the anisotropy-based localization bias, from 30 nm to 7 nm, in SMLM. We further characterize the emission anisotropy …
Accelerated Broadband Spectra And Attosecond Charge Migration Simulations Using Real-Time Time-Dependent Density Functional Theory,
2018
Louisiana State University and Agricultural and Mechanical College
Accelerated Broadband Spectra And Attosecond Charge Migration Simulations Using Real-Time Time-Dependent Density Functional Theory, Adam S. Bruner
LSU Doctoral Dissertations
In this dissertation, the calculations of light-matter interactions offer insight into the structure and dynamical response of electrons in molecular systems. Such information is useful for characterizing molecules, electronic structure, photochemistry, photomaterials, and a host of other applications. In the first part of this work, simulations of broadband absorption spectra are accelerated by the use of Pad´e approximanants of Fourier Transforms and dipole decomposition. Electronic absorption spectra from valence and core levels are obtained using time-dependent methods and compared to results from established perturbative techniques. In addition, core level absorption spectra are calculated for a nickel porphyrin and shown to …
Production Of Photoionized Plasmas In The Laboratory With X-Ray Line Radiation,
2018
Queen's University Belfast, UK
Production Of Photoionized Plasmas In The Laboratory With X-Ray Line Radiation, S. White, R. Irwin, J. R. Warwick, G. F. Gribakin, G. Sarri, F. P. Keenan, D. Riley, S. J. Rose, E. G. Hill, Gary J. Ferland, B. Han, F. Wang, G. Zhao
Physics and Astronomy Faculty Publications
In this paper we report the experimental implementation of a theoretically proposed technique for creating a photoionized plasma in the laboratory using x-ray line radiation. Using a Sn laser plasma to irradiate an Ar gas target, the photoionization parameter, ξ = 4πF/Ne, reached values of order 50erg cm s−1, where F is the radiation flux in erg cm−2 s−1. The significance of this is that this technique allows us to mimic effective spectral radiation temperatures in excess of 1 keV. We show that our plasma starts to be collisionally dominated …
Rotation Of Two-Petal Laser Beams In The Near Field Of A Spiral Microaxicon,
2018
Samara National Research University and RAS – Branch of the FSRC “Crystallography and Photonics” RAS, Molodogvardeyskaya 151, 443001, Samara, Russia
Rotation Of Two-Petal Laser Beams In The Near Field Of A Spiral Microaxicon, S. S. Stafeev, Liam O'Faolain, M. V. Kotlyar
Cappa Publications
Using a spiral microaxicon with the topological charge 2 and NA = 0.6 operating at a 532-nm wavelength and fabricated by electron-beam lithography, we experimentally demonstrate the rotation of a two-petal laser beam in the near field (several micrometers away from the axicon surface). The estimated rotation rate is 55 °/mm and linearly dependent on the on-axis distance, with the theoretical rotation rate being 53 °/mm. The experimentally measured rotation rate is found to be linear and coincident with the simulation results only on the on-axis segment from 1.5 to 3 mm. The experimentally measured rotation rate is 66 °/mm …
Assembling And Characterizing The Efficiency Of An Injection Locked Laser System For Cold Neutral Atom Optical Traps,
2018
California Polytechnic State University, San Luis Obispo
Assembling And Characterizing The Efficiency Of An Injection Locked Laser System For Cold Neutral Atom Optical Traps, Alexandra Papa Crawford
Physics
Creating a quantum computer requires a system of particles that can be well-controlled to achieve quantum operations. We need a large array of these particles – called qubits – with long coherence times, which can be initialized, operated on by single and two qubit gates, and read out. For neutral atoms, the qubit states are stable ground states that interact minimally with the environment, leading to long coherence times. Experimentally, the qubits are manipulated using carefully timed laser beam pulses with controlled frequency and intensity, but the outstanding issue for optically trapping cold atoms is finding a light pattern that …
Electron- And Positron-Impact Ionization Of Inert Gases,
2018
Old Dominion University
Electron- And Positron-Impact Ionization Of Inert Gases, R. I. Campeanu, H. R. J. Walters, Colm T. Whelan
Physics Faculty Publications
Triple-differential cross sections (TDCS) are presented for the electron and positron impact ionization of inert gas atoms in a range of geometries where a number of significant few body effects compete to define the shape of the TDCS. Using both positrons and electrons as projectiles has opened up the possibility of performing complementary studies which could effectively isolate competing interactions which cannot be separately detected in an experiment with a single projectile. A comparison is presented between theory and the recent experiments of [Gavin, deLucio, and DuBois, Phys. Rev. A95, 062703 (2017)] for e± and contrasted with the …
Out-Of-Plane (E,2E) Measurements And Calculations On He Autoionizing Levels As A Function Of Incident-Electron Energy,
2018
University of Kentucky
Out-Of-Plane (E,2E) Measurements And Calculations On He Autoionizing Levels As A Function Of Incident-Electron Energy, Nicholas L. S. Martin, C. M. Weaver, Brian N. Kim, B. A. Deharak, O. Zatsarinny, K. Bartschat
Physics and Astronomy Faculty Publications
Out-of-scattering-plane (e,2e) measurements and calculations are reported for the three singlet helium 2ℓ2ℓ′ autoionizing levels, with 80, 100, 120, 150, and 488 eV incident-electron energies, and scattering angles 60∘, 50.8∘, 45∘, 39.2∘, and 20.5∘, respectively. The kinematics are the same in all cases: the momentum transfer is K = 2.1 a.u., and ejected electrons are detected in a plane that contains the momentum-transfer direction and is perpendicular to the scattering plane. The results are presented as (e,2e) angular distributions energy integrated over …
The Spin-Forbidden A 4Σ−–X 2Π1/2 Transition Of Geh Detected In Absorption Using Intracavity Laser Spectroscopy,
2018
University of Missouri–St. Louis
The Spin-Forbidden A 4Σ−–X 2Π1/2 Transition Of Geh Detected In Absorption Using Intracavity Laser Spectroscopy, Jack Harms, Leah O’Brien, James O’Brien
Chemistry & Biochemistry Faculty Works
The a 4Σ−–X 2Π1/2 transition of GeH has been recorded in absorption for the first time using Intracavity Laser Spectroscopy (ILS). The GeH molecules were produced in a 0.40–0.60 A DC plasma discharge inside an aluminum hollow cathode, using 500 mTorr of Ar, 100 mTorr of H2, and 200 mTorr of GeH4. This cathode is located within the resonator cavity of a Coherent Verdi™ V-10 pumped dye laser. Effective path lengths for this series of measurements using the ILS method ranged from 2 to 7 km. Spectra were calibrated using the absorption spectrum of I2 collected from an extracavity cell, …
The Spin-Forbidden A^4z-—X^2n(1/2) Transition Of Geh Detected In Absorption Using Intracavity Laser Spectroscopy,
2018
University of Missouri-St. Louis
The Spin-Forbidden A^4z-—X^2n(1/2) Transition Of Geh Detected In Absorption Using Intracavity Laser Spectroscopy, James O'Brien, L. O'Brien, L. Harms
Chemistry & Biochemistry Faculty Works
The a 4Σ--X 2Π1/2 transition of GeH has been recorded in absorption for the first time using Intracavity Laser Spectroscopy (ILS). The GeH molecules were produced in a 0.40-0.60 A DC plasma discharge inside an aluminum hollow cathode, using 500 mTorr of Ar, 100 mTorr of H2, and 200 mTorr of GeH4. This cathode is located within the resonator cavity of a Coherent Verdi™ V-10 pumped dye laser. Effective path lengths for this series of measurements using the ILS method ranged from 2 to 7 km. Spectra were calibrated using the absorption spectrum of I2 collected from an extracavity cell, …
A Microresonator-Based Laser Doppler Velocity Sensor For Interplanetary Atmospheric Re-Entry,
2018
Southern Methodist University
A Microresonator-Based Laser Doppler Velocity Sensor For Interplanetary Atmospheric Re-Entry, Benjamin Wise
Mechanical Engineering Research Theses and Dissertations
In this thesis, a laser velocity sensor concept based on optical microresonators is presented and the application to spacecraft atmospheric entry is explored. The concept is based on the measurement of Doppler shift of back-scattered laser light. Specifically, the Doppler shift is detected by observing the whispering gallery optical modes (WGM) of a dielectric microresonator excited by the back scattered light from particulates and gas molecules. The microresonator replaces the typical Fabry-Perot interferometer and CCD camera system, thereby significantly reducing the size and weight of the overall detection system. This thesis presents proof-of-concept results for this measurement approach. The Doppler …
