Scene Change Artifacts In Fourier Transform Spectroscopy Of Temporally Changing Sources,
2010
Air Force Institute of Technology
Scene Change Artifacts In Fourier Transform Spectroscopy Of Temporally Changing Sources, Anthony M. Young
Theses and Dissertations
Improved understanding of midwave infrared (1-5 micron) spectral emissions from detonation fireballs is needed to develop phenomenological models for battle space optical forensics. The ability to measure radiance over a wide band pass at arbitrary resolutions make Fourier-transform spectrometers (FTS) an attractive tool. However, interferometer based spectroscopic measurements can be corrupted when the observed intensity changes during data acquisition. While small, random fluctuations in scene intensity translate into noise, systematic variations introduce scene-change artifacts (SCAs) into Fourier-transformed spectrum.
Passive Ranging Using Infra-Red Atmospheric Attenuation,
2010
Air Force Institute of Technology
Passive Ranging Using Infra-Red Atmospheric Attenuation, Douglas J. Macdonald
Theses and Dissertations
Methods of estimating range to an emissive target based on the depth of an atmospheric absorption band are demonstrated. The present work uses measurements of the CO2 absorption band centered at 2.0 µm where signal-to-background ratios are maximum for many applications. Model results, based on high-resolution transmission molecular absorption (HITRAN) database cross sections, are used to predict range accuracy at ranges of up to 50 km and are compared with short range (<5km) experimental results. The spectra of 23 high explosive events were used to validate the model. Using the assumption of a blackbody spectrum, extracted ranges consistently underestimated the true range by approximately 13%. By incorporating the stoichiometry of the fireball from previous research and using particulate contribution as a parameter, the error for the range estimates could be reduced to 3%.
Positron Annihilation Ratio Spectroscopy (Psars) Applied To Positronium Formation Studies,
2010
Air Force Institute of Technology
Positron Annihilation Ratio Spectroscopy (Psars) Applied To Positronium Formation Studies, Robert C. Slaughter
Theses and Dissertations
A Positron Annihilation of Radiation Spectrometer (PsARS) was developed and characterized. PsARS spectroscopy as well as digital Positron Annihilation Lifetime Spectroscopy (PALS) was applied to measure positronium formation on gold nanoparticles deposited through an evaporative method onto a thin capillary tube. This gold coated capillary tube was designed to be used for positronium lifetime studies in local electric field experiments. High local electric fields can polarize a positron-electron pair, which may result in an extended lifetime of the positron. These fields may be created through the interaction of an external electric field with silver nanoparticles deposited onto the surface of …
Hard Collisions In Rubidium Using Sub-Doppler Spectroscopy,
2010
Air Force Institute of Technology
Hard Collisions In Rubidium Using Sub-Doppler Spectroscopy, Douglas E. Thornton
Theses and Dissertations
To better understand the laser kinetics of an alkali gain medium, hard collisions, or velocity-changing collisions, has been studied and a velocity-changing collisional rate has been calculated. Previous works have studied these collisions, but no rate has been calculated. Using the precise tool of sub-Doppler spectroscopy, atomic hard collisions can be observed. The collected spectra are fitted with two different line shapes to demonstrate the accuracy of this method. From the fits, the number of hard collisions can be extracted. The time scale of the hard collisions in rubidium is interpolated by varying the chopping frequency of the pump beam, …
Bosonic Analog Of The Klein Paradox,
2010
Illinois State University
Bosonic Analog Of The Klein Paradox, R E. Wagner, M R. Ware, Q Su, Rainer Grobe
Faculty publications – Physics
The standard Klein paradox describes how an incoming electron scatters off a supercritical electrostatic barrier that is so strong that it can generate electron- positron pairs. This fermionic system has been widely discussed in textbooks to illustrate some of the discrepancies between quantum mechanical and quantum field theoretical descriptions for the pair creation process. We compare the fermionic dynamics with that of the corresponding bosonic system. We point out that the direct counterpart of the Pauli exclusion principle (the central mechanism to resolve the fermionic Klein paradox) is stimulated emission, which leads to the resolution of the analogous bosonic paradox.
Dynamics Of Strong Radio Sources With Umrt-Ii.,
2010
Universiti Malaya
Dynamics Of Strong Radio Sources With Umrt-Ii., Mohammed Awid Al-Amri
Student Works (2010-2019)
Radio astronomy is a new field in Southeast Asia. University Malaya Radio Telescope UMRT-II is located on the roof of Block B in the Department of Physics, University of Malaya to detect neutral hydrogen emission line. Doppler shift of 1420.4 MHz for different radio sources were observed to determine their dynamics. By measuring the Doppler shift, the velocity V, of each radio source can be determined. Hence the dynamic of radio source can be deduced. The radio spectrum of Coma Cluster was also analyzed and its dark matter content was estimated. The observation time effort was investigated for Coma Cluster …
Magnetodielectric Coupling Of Infrared Phonons In Single-Crystal Cu2oseo3,
2010
University of Florida
Magnetodielectric Coupling Of Infrared Phonons In Single-Crystal Cu2oseo3, K. H. Miller, X. S. Xu, H. Berger, E. S. Knowles, D. J. Arenas, M. W. Meisel, D. B. Tanner
Xiaoshan Xu Papers
Reflection and transmission as a function of temperature (5–300 K) have been measured on a single crystal of the magnetoelectric ferrimagnetic compound Cu2OSeO3 utilizing light spanning the far infrared to the visible portions of the electromagnetic spectrum. The complex dielectric function and optical properties were obtained via Kramers-Kronig analysis and by fits to a Drude-Lortentz model. The fits of the infrared phonons show a magnetodielectric effect near the transition temperature (Tc~60 K). Assignments to strong far-infrared phonon modes have been made, especially those exhibiting anomalous behavior around the transition temperature.
Tunable Band Gap In Bi(Fe1−Xmnx)O3 Films,
2010
University of Nebraska-Lincoln
Tunable Band Gap In Bi(Fe1−Xmnx)O3 Films, X. S. Xu, J. F. Ihlefeld, J. H. Lee, O. K. Ezekoye, E. Vlahos, R. Ramesh, V. Gopalan, X. Q. Pan, D. G. Schlom, J. L. Musfeldt
Xiaoshan Xu Papers
In order to investigate band gap tunability in polar oxides, we measured the optical properties of a series of Bi(Fe1−xMnx)O3 thin films. The absorption response of the mixed metal solid solutions is approximately a linear combination of the characteristics of the two end members, a result that demonstrates straightforward band gap tunability in this system.
Adsorption-Controlled Growth Of Bimno3 Films By Molecular-Beam Epitaxy,
2010
Cornell University
Adsorption-Controlled Growth Of Bimno3 Films By Molecular-Beam Epitaxy, J. H. Lee, X. Ke, R. Misra, J. F. Ihlefeld, X. S. Xu, Z. G. Mei, T. Heeg, M. Roeckerath, J. Schubert, Z. K. Liu, J. L. Musfeldt, P. Schiffer, D. G. Schlom
Xiaoshan Xu Papers
We have developed the means to grow BiMnO3 thin films with unparalleled structural perfection by reactive molecular-beam epitaxy and determined its band gap. Film growth occurs in an adsorption-controlled growth regime. Within this growth window bounded by oxygen pressure and substrate temperature at a fixed bismuth overpressure, single-phase films of the metastable perovskite BiMnO3 may be grown by epitaxial stabilization. X-ray diffraction reveals phase-pure and epitaxial films with w rocking curve full width at half maximum values as narrow as 11 arc sec (0.003°). Optical absorption measurements reveal that BiMnO3 has a direct band gap of 1.1±0.1 …
Lattice Dynamical Probe Of Charge Order And Antipolar Bilayer Stacking In Lufe2o4,
2010
University of Nebraska-Lincoln
Lattice Dynamical Probe Of Charge Order And Antipolar Bilayer Stacking In Lufe2o4, X. S. Xu, J. De Groot, Q.-C. Sun, B. C. Sales, D. Mandrus, M. Angst, A. P. Litvinchuk, J. L. Musfeldt
Xiaoshan Xu Papers
We investigated the infrared response of LuFe2O4 through the series of charge, magnetic, and structural transitions. All vibrational modes couple strongly to the charge order, whereas the LuO zone-folding modes are also sensitive to magnetic order and structural distortion. The dramatic splitting of the LuO2 layer mode is attributed to charge-rich/poor proximity effects and its temperature dependence reveals the antipolar nature of the W layer pattern.
Optical Properties Of Quasi-Tetragonal Bifeo3 Thin Films,
2010
University of Tennessee
Optical Properties Of Quasi-Tetragonal Bifeo3 Thin Films, P. Chen, N. J. Podraza, X. S. Xu, A. Melville, E. Vlahos, V. Gopalan, R. Ramesh, D. G. Schlom, J. L. Musfeldt
Xiaoshan Xu Papers
Optical transmission spectroscopy and spectroscopic ellipsometry were used to extract the optical properties of an epitaxially grown quasi-tetragonal BiFeO3 thin film in the near infrared to near ultraviolet range. The absorption spectrum is overall blue shifted compared with that of rhombohedral BiFeO3, with an absorption onset near 2.25 eV, a direct 3.1 eV band gap, and charge transfer excitations that are ~0.4 eV higher than those of the rhombohedral counterpart. We interpret these results in terms of structural strain and local symmetry breaking.
Robust Isothermal Electric Control Of Exchange Bias At Room Temperature,
2010
University of Nebraska-Lincoln
Robust Isothermal Electric Control Of Exchange Bias At Room Temperature, Xi He, Ning Wu, Anthony N. Caruso, Elio Vescovo, Kirill D. Belashchenko, Peter A. Dowben, Christian Binek
Kirill Belashchenko Publications
Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with highspeed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr2O3 has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr2O3 single crystal, we achieve reversible, room-temperature isothermal switching …
Infrared Skin Damage Thresholds From 1940-Nm Continuous-Wave Laser Exposures,
2010
Air Force Research Laboratory
Infrared Skin Damage Thresholds From 1940-Nm Continuous-Wave Laser Exposures, Jeffrey W. Oliver, David J. Stolarski, Gary D. Noojin, Harvey M. Hodnett, Corey A. Harbert, Kurt J. Schuster, Michaedl F. Foltz, Semih S. Kumru, Clarence P. Cain, C. J. Finkeldei, Gavin Buffington, Isaac D. Noojin, Robert J. Thomas
Physics Faculty Publications
A series of experiments are conducted in vivo using Yucatan mini-pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1940-nm continuous-wave thulium fiber laser irradiation. Experiments employ exposure durations from 10 ms to 10 s and beam diameters of approximately 4.8 to 18 mm. Thermal imagery data provide a time-dependent surface temperature response from the laser. A damage endpoint of minimally visible effect is employed to determine threshold for damage at 1 and 24 h postexposure. Predicted thermal response and damage thresholds are compared with a numerical model of optical-thermal interaction. Results are compared …
Demonstration Of A Neutral Atom Controlled-Not Quantum Gate,
2010
College of Saint Benedict/Saint John's University
Demonstration Of A Neutral Atom Controlled-Not Quantum Gate, L. Isenhower, E. Urban, X. L. Zhang, A. T. Gill, T. Henage, Todd A. Johnson, T. G. Walker, M. Saffman
Physics Faculty Publications
We present the first demonstration of a CNOT gate between two individually addressed neutral atoms. Our implementation of the CNOT uses Rydberg blockade interactions between neutral atoms held in optical traps separated by >8 μm. Using two different gate protocols we measure CNOT fidelities of F=0.73 and 0.72 based on truth table probabilities. The gate was used to generate Bell states with fidelity F=0.48±0.06. After correcting for atom loss we obtain an a posteriori entanglement fidelity of F=0.58.
Imaging Live Cells Grown On A Three Dimensional Collagen Matrix Using Raman Microspectroscopy,
2010
Technological University Dublin
Imaging Live Cells Grown On A Three Dimensional Collagen Matrix Using Raman Microspectroscopy, Franck Bonnier, Peter Knief, Basil Lim, Aidan Meade, Jennifer Dorney, Kunal Bhattacharya, Fiona Lyng, Hugh Byrne
Articles
Three dimensional collagen gels have been used as matrices for the imaging of live cells by Raman spectroscopy. The study is conducted on a human lung adenocarcinoma (A549) and a spontaneously immortalized human epithelial keratinocyte (HaCaT) cell line. The lateral resolution of the system has been estimated to be
Preparing A Vacuum Chamber To Trap Atoms, And The Principles Of A Magneto-Optical Trap,
2010
California Polytechnic State University - San Luis Obispo
Preparing A Vacuum Chamber To Trap Atoms, And The Principles Of A Magneto-Optical Trap, Grant Rayner
Physics
No abstract provided.
Direct Measurements Of Island Growth And Step-Edge Barriers In Colloidal Epitaxy,
2010
Cornell University
Direct Measurements Of Island Growth And Step-Edge Barriers In Colloidal Epitaxy, Rajesh Ganapathy, Mark R. Buckley, Sharon J. Gerbode, Itai Cohen
All HMC Faculty Publications and Research
Epitaxial growth, a bottom-up self-assembly process for creating surface nano- and microstructures, has been extensively studied in the context of atoms. This process, however, is also a promising route to self-assembly of nanometer- and micrometer-scale particles into microstructures that have numerous technological applications. To determine whether atomic epitaxial growth laws are applicable to the epitaxy of larger particles with attractive interactions, we investigated the nucleation and growth dynamics of colloidal crystal films with single-particle resolution. We show quantitatively that colloidal epitaxy obeys the same two-dimensional island nucleation and growth laws that govern atomic epitaxy. However, we found that in colloidal …
Investigation Of The Influence Of High Risk Human Papillomavirus On The Biochemical Composition Of Cervical Cancer Cells Using Vibrational Spectroscopy,
2010
Technological University Dublin
Investigation Of The Influence Of High Risk Human Papillomavirus On The Biochemical Composition Of Cervical Cancer Cells Using Vibrational Spectroscopy, Kamila Ostrowska, Alison Malkin, Aidan Meade, John O'Leary, Cara Martin, Cathy Spillane, Hugh Byrne, Fiona Lyng
Articles
The main aetiology of cervical cancer is infection with high risk human papillomavirus (HPV). Cervical cancer is almost 100% curable if detected in the early stages. Thus, information about the presence and levels of HPV in patient samples has high clinical value. As current screening methods, such as the Pap smear test, are highly subjective and in many cases show low sensitivity and specificity, new supportive techniques are desirable to improve the quality of cervical cancer screening. In this study, vibrational spectroscopic techniques (Raman and Fourier Transform Infra Red absorption) have been applied to the investigation of four cervical cancer …
Deposition Of High-Quality Hfo2 On Graphene And The Effect Of Remote Oxide Phonon Scattering,
2010
Pennsylvania State University
Deposition Of High-Quality Hfo2 On Graphene And The Effect Of Remote Oxide Phonon Scattering, K. Zou, X. Hong, D. Keefer, J. Zhu
Xia Hong Publications
We demonstrate atomic layer deposition of high-quality dielectric HfO2 films on graphene and determine the magnitude of remote oxide surface phonon scattering in dual-oxide structures. The carrier mobility in these HfO2-covered graphene samples reaches 20 000 cm2/Vs at low temperature. Distinct contributions to the resistivity from surface optical phonons in the SiO2 substrate and the HfO2 overlayer are isolated. At 300 K, surface phonon modes of the HfO2 film centered at 54 meV limit the mobility to approximately 20 000 cm2/Vs.
Unusual Resistance Hysteresis In N-Layer Graphene Field Effect Transistors Fabricated On Ferroelectric Pb(Zr0.2Ti0.8)O3,
2010
University of Nebraska–Lincoln
Unusual Resistance Hysteresis In N-Layer Graphene Field Effect Transistors Fabricated On Ferroelectric Pb(Zr0.2Ti0.8)O3, X. Hong, J. Hoffman, A. Posadas, K. Zou, C. H. Ahn, J. Zhu
Xia Hong Publications
We have fabricated n-layer graphene field effect transistors on epitaxial ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT) thin films. At low gate voltages, PZT behaves as a high-k dielectric with k up to 100. An unusual resistance hysteresis occurs in gate sweeps at high voltages, with its direction opposite to that expected from the polarization switching of PZT. The relaxation of the metastable state is thermally activated, with an activation barrier of 50–110 meV and a time constant of 6 h at 300 K. We attribute its origin to the slow dissociation/recombination dynamics of water molecules adsorbed at …
