Astrophysics and Astronomy Commons^™

Universal Disorder In Organic Semiconductors Due To Fluctuations In Space Charge, Tzucheng Wu

Physics & Astronomy ETDs

This thesis concerns the study of charge transport in organic semiconductors. These materials are widely used as thin-film photoconductors in copiers and laser printers, and for their electroluminescent properties in organic light-emitting diodes. Much contemporary research is directed towards improving the efficiency of organic photovoltaic devices, which is limited to a large extent by the spatial and energetic disorder that hinders the charge mobility. One contribution to energetic disorder arises from the strong Coulomb interactions between injected charges with one another, but to date this has been largely ignored. We present a mean-field model for the effect of mutual interactions …

Single Particle Tracking: Analysis Techniques For Live Cell Nanoscopy., Peter K. Relich

Physics & Astronomy ETDs

Single molecule experiments are a set of experiments designed specifically to study the properties of individual molecules. It has only been in the last three decades where single molecule experiments have been applied to the life sciences; where they have been successfully implemented in systems biology for probing the behaviors of sub-cellular mechanisms. The advent and growth of super-resolution techniques in single molecule experiments has made the fundamental behaviors of light and the associated nano-probes a necessary concern among life scientists wishing to advance the state of human knowledge in biology. This dissertation disseminates some of the practices learned in …

Memory Effects In Brownian Motion, Random Walks Under Confining Potentials, And Relaxation Of Quantum Systems, Matthew Chase

Physics & Astronomy ETDs

This dissertation is a report on a number of distinct topics in the field of non-equilibrium statistical mechanics including the evolution of classical as well as quantum systems.

The evolution of an object that is described by the Ornstein-Uhlenbeck process generalized through a time-nonlocal attraction is considered. The time-nonlocality is taken to be represented in the Langevin description through the presence of memory. Analysis of the Langevin equation is performed for algebraic and delay-type memories. An equivalent \emph{bona-fide} Fokker-Planck equation is constructed.

A random walker subjected to a non-standard confining potential, taken to be a piece-wise linear function, is analyzed. …

Extending The Reach Of Directional Dark Matter Experiments Through Novel Detector Technologies, Nguyen S. Phan

Physics & Astronomy ETDs

Dark matter is believed to comprise over 80% of the matter in the Universe. Its composition could be in the form of weakly interacting massive particles (WIMPs), which are predicted by extensions of the Standard Model, namely supersymmetric theories. Even though hints of its existence were detected in astronomical observations over eighty years ago, its detection through means other than the gravitational influence on observable luminous matter still eludes us.

Currently, there are many ongoing direct detection experiments, that aim to measure the signals left by the elastic scattering of WIMPs with nuclei in the detector target material. The detection …

Probing Dark Matter-Neutrino Connection Via Indirect Detection Experiments, Bradley Knockel

Physics & Astronomy ETDs

Various evidence reveals that dark matter is a primary component of this universe. The amount of dark matter is known, but its identity is a mystery. To determine its properties, efforts to detect and produce dark matter are underway. Dark matter annihilations throughout the galaxy may produce photons, neutrinos, and cosmic rays. Neutrino and photon detectors may then indirectly detect dark matter by detecting these annihilation products. The annihilation rate, dark matter mass, and dark matter scattering rate off of matter affect the signals received at Earth. These signals can therefore probe the identity of dark matter, especially if dark …

Resting-State Connectivity Dynamics In The Human Brain Using High-Speed Fmri, Kishore Vakamudi

Physics & Astronomy ETDs

Resting-state fMRI using seed-based connectivity analysis (SCA) typically involves regression of the confounding signals resulting from movement and physiological noise sources. This not only adds additional complexity to the analysis but may also introduce possible regression bias. We recently introduced a computationally efficient real-time SCA approach without confound regression, which employs sliding-window correlation analysis with running mean and standard deviation (meta-statistics). The present study characterizes the confound tolerance of this windowed seed-based connectivity analysis (wSCA), which combines efficient decorrelation of confounding signal events with high-pass filter characteristics that reduce sensitivity to drifts. The confound suppression and the strength of resting-state …

Quantum Information In Rydberg-Dressed Atoms, Tyler Emerson Keating

Physics & Astronomy ETDs

In any physical platform, two ingredients are essential for quantum information processing: single-qubit control, and entangling interactions between qubits. Neutral atoms can be individually controlled with high fidelity and are resilient to environmental noise, making them attractive candidates for implementing quantum information protocols. However, achieving strong interactions remains a major obstacle. One way to increase the interaction strength between neutral atoms is to excite them into high-lying Rydberg states, which exhibit large electric dipole moments (and by extension, strong electric dipole-dipole interactions). By slowly ramping up the Rydberg level coupling in a system, one can "dress'' the atomic ground states …

The Biophysical Effects Of Deuterium Oxide On Biomolecules And Living Cells Through Open Notebook Science., Anthony Salvagno

Physics & Astronomy ETDs

This dissertation explores various effects of deuterium oxide (D2O also known as heavy water) in nature. Water is everywhere and interacts with just about everything. As such, it would be quite a daunting task to characterize every effect that water exhibits on everything in the universe. This research is a small piece of the puzzle, and provides some fundamental understanding of how water interacts with other molecules. This is done from two viewpoints: (1) the effects of heavy water on living cells and (2) the effects of heavy water on molecules. Varying concentrations of deuterium oxide were used as the …

The Evaluation Of Erk1 Dimerization Models Using Fluorescence Correlation Spectroscopy And The Development Of Analysis Algorithms For Single-Molecule Super Resolution, Fang Huang

Physics & Astronomy ETDs

In this dissertation, we describe three advancements in the area of fluorescence spectroscopy and microscopy. First, we have implemented Fluorescence Correlation Spectroscopy on a home-built confocal microscope. We proposed F/N analysis which stands for the ratio between average intensity and average number of moving objects in FCS as a method to detect dimerization of fluorescently tagged proteins diffusing in three dimensions. We used the technique to evaluate the dimerization hypothesis of ERK1 protein during nucleus translocation and it shows that ERK1 nucleus translocation is dimerization independent. Second, we have developed a multi-emitter analysis algorithm for single-molecule super resolution techniques that …

Silcom Quantum Walls: Fabrication And Opticla Analysis, An-Shyang Chu

Physics & Astronomy ETDs

The fabrication and optical analysis of well-defined Si quantum walls (periodic slabs) are presented. Using a unique combination of interference lithography and wet-­chemical KOH etching, vertically-standing, periodic Si rectangular slabs are fabricated with a slab thickness ranging from a few nm to ~ 200 nm. Each slab has its three principal axes in the,anddirection, and each slab surfaces is extended in the-plane and normal to thedirection. These samples are used to study the effects of the size confinement on the crystal properties of Si. Raman scattering experiment is carried out because the scattering of the phonons is highly dependent on …

Design Of A Device Independent Computer Graphic Software Package, An-Shyang Chu

Physics & Astronomy ETDs

The fabrication and optical analysis of well-defined Si quantum walls (periodic slabs) are presented. Using a unique combination of interference lithography and wet-­chemical KOH etching, vertically-standing, periodic Si rectangular slabs are fabricated with a slab thickness ranging from a few nm to ~ 200 nm. Each slab has its three principal axes in the <110>, <112> and <111> direction, and each slab surfaces is extended in the <110>-<112> plane and normal to the <111> direction. These samples are used to study the effects of the size confinement on the crystal properties of Si. Raman scattering experiment is carried out because the scattering of …

Saturated Solar Ponds: Modified Equations And Results Of A Laboratory Experiment, Markus Karl Rothmeyer

Physics & Astronomy ETDs

The diffusion equation for salt gradient solar ponds has been modified to include the Soret effect (a thermal cross-effect due to the temperature gradient). The contribution of the Soret effect to the diffusion flux of salt is shown to be on the order of 4% in the winter and 28% in the summer for the UNM NaCl solar pond. The traditional stability criterion for solar ponds remains practically unchanged by the Soret effect. However, the contribution of non-constant properties (diffusion coefficient, thermal diffusivity and viscosity)--which have been neglected so far--seems to be significant. Saturated solar ponds are described by a …

Energy And Angular Distribution Of Neutrons From Proton-Proton Inelastic Scattering At 800 Mev, Ted Dean Rupp

Physics & Astronomy ETDs

The neutron energy spectra from the reaction p + p → n + p + π⁺ for an incident proton energy of 800 MeV was measured for all phase space. ++ The channels were dominated by △⁺⁺. (1232) resonance and had a total cross section of 16 ± 1.5 mb. Also, the data demonstrated the dominance of Sand P waves. The experimental results were compared to isobar, phase space and a one pion exchange model. The isobar and phase space models failed to predict the experimental results; however, the one pion exchange model fit the data for …

Polynomial And Rational Fraction Representations Of A Diatomic Molecular Potential, Paul R. Findley

Physics & Astronomy ETDs

A method is presented for approximating a diatomic molecular vibrational potential by fitting to modified forms of the potential. Power's numerical Born-Oppenheimer potential for the H₂⁺ electronic ground state is the potential used in this thesis. The modification procedure is to multiply the potential by various powers of the internuclear separation. This removes the troublesome Coulomb pole at zero internuclear separation. Graphs of the modified forms are presented. Polynomials were fitted directly to the potential, to the modified forms, and to the pure electronic energy. Comparisons are made among the various representations of the potential obtained from the …

Precipitation Phenomena In Antimony-Implanted Aluminium, Richard Allen Kant

Physics & Astronomy ETDs

An experimental and theoretical study of the influence of temperature flux, and fluence on the formation and evolution of compounds formed by ion implantation has been conducted. Transmission electron microscopy was used to determine the size distribution of AJSb precipitates resulting from implanting single crystal A1 with Sb. In addition, the role of ion damage was investigated using both Ar and Al bombardment. These experiments show that for samples which initially contain no Sb, the number density of pre• cipitates decreases with increasing fluence and temperature, and with decreasing flux.

Measurement Of The H- Photodetachment Cross Section In The Continuum Region From 1.5 To 10.5 Ev, Mohammad Hassan Sharifian-Attar

Physics & Astronomy ETDs

We have measured the H photodetachment cross section in the photon energy range from 1.5 to 10.5 eV, using a colliding beam method. The H beam with an energy of 800 MeV, at Los Alamos Linear Accelerator, was intersected by a nitrogen laser beam with a photon energy of 3 .678 eV in the lab frame. We changed the energy of the pho"ton in the H rest frame, through the Doppler effect, by varying the angle between the laser and the H beams. The magnitude of the Doppler shift was enough to cover the entire range from 1.5 to 10.5 …

Neutron-Proton Elastic Scattering At 790 Mev, Roger Daniel Carlini

Physics & Astronomy ETDs

The forward n-p differential cross-section is measured at 790 Mev from 9.5 to 60. degrees in the center of mass. The systematic errors are less than 4.0%. The differential cross-section is parameterized by the function dσ/dΩ = A e^bt, where t is the momentum transfer between the incoming and outgoing neutrons in (GeV/C)², and A and b are constants having the values A= 9.757±.069, b= 5.052±.045. With 36 data points the x² is 55. The magnitude of the ratio of the real to imaginary part of the forward scattering amplitude is found to be .3501±.14.

Convection In Pulsating Stars, Michael John Robert Costello

Physics & Astronomy ETDs

Stellar models using mixing length convection in a linear calculation show a red edge to the instability strip. The models are of a 6 solar mass, 1 x 10 ergs/sec luminos­ity, King 4A composition, cepheid variable star, for various values of effective temperature, Te, and mixing length parameter, a. Results are obtained with an assumed instantaneous adjustment of the convective flux to changes in the local stellar conditions. Calculations of the convective time de­lay show it to be small compared to the period, under the assumption that the convective time delay is due solely to the inertia of convective bubbles. …

Heights Of Formation For Certain Solar Spectral Lines, Erik J. Schwendeman

Physics & Astronomy ETDs

Heights of formation are calculated for several of the solar spectral lines studied by the National Aeronautics and Space Administration - Goddard Space Flight Center (NASA-GSFC) New Mexico Solar Station at Sacramento Peak Observatory. These lines are Ca II H, K, 8498 Å and 8542 Å, MgI b₁, NaI D₁ and D₂ and Sil 4103 Å. I calculate the heights of formation for each of these lines along with upper and lower confidence limits representing the height region where 90% of the total intensity of the line is formed in the solar photosphere and chromosphere. The …

A Covariant Approach To Wave Equations In General Relativity, Alan L. Dudley

Physics & Astronomy ETDs

A formalism for the manipulation of tensors in both real and complex spacetimes is introduced, which utilizes the irreducible representations of the Lorentz group to substantially simplify certain general relativistic calculations. The notation is completely covariant and is most effective for massless field calculations. Results emerge which eliminate the majority of the algebraic burden of the traditional Newman­Penrose formalism and, simultaneously, allow the reader to understand both the physical and geometrical meanings of each step of the derivations. The technique developed is well suited for perturbation analyses. Consequently, the perturbed wave equations for massless fields are examined. The notation has …

Infrared Observations Of Hii Regions And Comet West, Paul A. Heckert

Physics & Astronomy ETDs

In Chapter 1, I outline the methods of making ground-based infrared observations. I concentrate on the observational procedures rather than the instrumental design. Near-infrared observations of S 156A, _S 158A, S 159A, S 162A₁, S 228, and G 45. 5 + 0 .1 (#2) made with a beam size of ̴1 are used to estimate the total near infrared flux. After correcting for the line of sight extinction the near infrared luminosities are greater than the Lyman-α luminosities inferred from radio observations. A strong double peaked infrared source was discovered near the region of G 25.3-0.1. The infrared …

Plasma Sheath Analysis By Computer Simulation, Leo J. Rahal

Physics & Astronomy ETDs

The time development of a fully ionized, dense two-component plasma is investigated through the use of a one-dimensional particle simulation code. The plasma is initially composed of two distinct regions. One region is a uniform plasma in which electrons and ions are at the sane temperature and have no electric fields due to charge separ­ation. The other region contains a charge separation of electrons and ions resulting in an electric field. There also exists an electron current which produces a confining magnetic field. This is the sheath region between the neutral plasma and the confining magnetic field. The simulation occurs …

Theoretical Studies Of Nucleic Acid Sugar Ring Analogs, Ali-Reza Hashemi-Attar

Physics & Astronomy ETDs

Extended Hueckel theory (EHT) was used to study analogs of sugar rings in nucleic acid monomers. The energy gradient in a variable metric algorithm was used to find the potential energy along the pseudorotation path. Use of the energy gradient made it possible to permit 34 degrees of freedom in a molecule. Seven molecules and their isomers were studied. These were: 3-hydroxy2-methyl tetrahydrofuran, 2-ami no-4-hydroxytetrahydrofiJran, 5-ami no3-hydroxy-2-methyltetrahydrofuran (deoxyribonucleic acid analog), 3,4-dihydroxy-2-methyltetrahydrofuran, 2-amino-3,4-dihydroxytetrahydrofuran, 2-amino-5-methyltetrahydrofuran, and 2-amino-3,4-dihydroxy-5-methyltetrahydrofuran (ribonucleic acid analog).

It was shown that the difference in sum of total overlap populations (TOP) for all pairs of atoms between two related conformations …

Neutron Spectra At Zero Degrees From Proton Bombardment Of Light Nuclei At Medium Energies, Constantine George Cassapakis

Physics & Astronomy ETDs

The neutron-momentum spectra at 0° resulting from proton bombardment of 9Be, 12C, and 27Al at Tp=633MeV, and those of 12C and 27Al at Tp=786 MeV, have been measured at the LAMPF (Los Alamos Meson Physics Facility)-Nucleon Physics Laboratory.

The measurements utilized the recently developed single arm, multiwire proportional counter, recoil-proton, magnetic spectrometer. I

dentification of the recoil charged particles was achieved through momentum analysis and simultaneous time­of-flight determination for each particle constituting a valid event.

The momentum and energy resolutions achieved are about 1% and 1.4%, respectively, at the incident proton energies considered.

The spectra for 9Be and 27Al exhibit …

The Determination Of Double Mode Variable Star Periods, Arne A. Henden

Physics & Astronomy ETDs

ABSTRACT

The problem of determining the periods of objects oscillating in one or more modes is discussed. Although the methods described are applicable to many different kinds of objects and observations, the discussion has been limited to double mode Cepheid stars.

Two methods of solution are followed in detail. An autocorrela­tion technique based on the scatter of points in an amplitude-phase plane is used for most cases. A means of calculating smoothed mean curves is discussed. A Fourier transform method is presented for closely spaced data points, with prewhitening included for accurate secondary period and amplitude determinations.

Three test problems …

A Satellite Study Of The High Energy Proton Environment Under The Radiation Belt, Kailash Chandra Dhingra

Physics & Astronomy ETDs

Proton data outside of the South Atlantic Radiation anomaly (in the regions where h_min < 0) from the University of New Mexico High Energy Neutron and Proton Detector aboard OSO-6 satellite were analyzed in the present work. The detector was useful in the energy range from 75-145 Mev and the data were obtained during the period from August 1969 to January 1971. The altitude of the satellite varied from about 480 Km to 580 Km. Since the observed proton flux resulted from different source mechanisms a procedure was developed that allowed us to compute and separate the contributions made by different mechanisms in the observed protons. New evidence was derived from the study of the Down-Up asymmetry both along the field direction and the zenith of the look direction (ZAP angle) which substantiated the hypothesis that either one or both of the processes of the radial and the pitch angle diffusion play active roles in the origin and the distributions of the protons in the inner radiation belt. It was argued that processes drive the trapped protons in the radiation belt into the regions where stable trapping is not possible and thus contribute to the observed protons in these regions. We were further able to compute the total diffusing flux; however, it was assumed that both the Splash and the Re-entrant albedo proton fluxes were equal. Since this assumption was not very accurate, an incorrect estimation of the diffusing proton flux might have resulted. In addition to the above, the flux and the energy spectrum of the albedo protons were derived at three different regions. These were then compared with the results of other investigators. Discrepencies in both the flux and the energy spectrum were observed. Our flux value of 1.05 protons/m² -sec-ster-Mev for the Re-entrant albedo at an energy of 85 Mev in the region where L = 2.5 was about a factor of two and a half higher than estimated by Ray (1967). No west-east asymmetry was observed in the true proton flux (proton flux obtained by subtracting the background contamination from the observed proton flux), within the limits of the experimental error. Since such an asymmetry was expected if we assume that the albedo protons alone constitute the true protons, it was concluded …

A Theoretical Study Of The Predissociation Of The O2 B 3Ʃu- Electronic State, Richard Allan Harris

Physics & Astronomy ETDs

It has been known for many decades that the B 3Ʃ_u^- state of the oxygen molecule, the upper state of the Schumann-Runge electronic band system, is predissociated. The predissociation has been attributed to the 3Π_u state, arising from the ground state, separated atom, manifold of molecular states, by previous investigators with the crossing point of the potential energy curves ranging from somewhere on the inner limb to somewhere on the outer limb of the bound excited B 3Ʃ_u^- state. This research has been undertaken to quantitatively describe the observed predissociation. A model with adjustable parameters …

Pi-Meson Absorption On The Deuteron, Bruce Goplen

Physics & Astronomy ETDs

The nonradiative absorption of positive pi-mesons by deuterons is studied within the framework of Lagrangian formalism and the impulse approximation. The pi-nucleon absorption interaction is taken to be pseudovector; however, the reaction is believed to be dominated by pi­nucleon scattering. Thus, the main thrust of the investigation is directed at three different approaches to the scattering interaction. First, the Hamiltonian formalism of Koltun and Reitan is extended to include energetic pions. An off-shell form is chosen for p-wave scattering which at low energy reduces to the field-theoretical result of Klein. In the second approach, the S-matrix formalism of Lazard, Ballot …

General Geodesic Motion In The Extended Kerr Manifold, Richard H. St. John

Physics & Astronomy ETDs

The timelike and null geodesics in the Kerr metric describe important properties of the space surrounding a rotating black hole. The general characteristics of these geodesics, with an emphasis on those on the axis of symmetry and the equatorial plane, are found in this paper. On the axis of symmetry, the behavior of all timelike and null geodesics is completely described. The accessibility of various spaces added for geodesic completeness in the extended manifold is found by making local observations of geodesics in one coordinate patch from geodesics in another. The analysis on the equatorial plane shows that for a …

Neutron And Proton Measurements Of Oso-6 Near The South Atlantic Radiation Anomaly., Philip Jay Cooper

Physics & Astronomy ETDs

The University of New Mexico High-Energy Neutron Experiment flown aboard NASA Satellite OS0-6 in 1969 was designed and built to study neutrons at an altitude of 􀀄500 km, above the earth's dense atmosphere. The detector was a proton recoil telescope with directional discrimination and was sensitive to protons as well as neutrons. Neutron data from August, 1969 to January, 1971 was analyzed in the energy range 40-120 Mev. Proton data in the energy range 60-170 Mev obtained during October and November of 1969 was also analyzed. Analysis was limited to the region of space known as the South Atlantic Radiation …