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Light quasiparticles dominate electronic transport in molecular crystal field-effect transistors

Description: We report on an infrared spectroscopy study of mobile holes in the accumulation layer of organic field-effect transistors based on rubrene single crystals. Our data indicate that both transport and infrared properties of these transistors at room temperature are governed by light quasiparticles in molecular orbital bands with the effective masses m[small star, filled]comparable to free electron mass. Furthermore, the m[small star, filled]values inferred from our experiments are in agreement wit… more
Date: March 1, 2007
Creator: Li, Z. Q.; Podzorov, V.; Sai, N.; Martin, Michael C.; Gershenson, M. E.; Di Ventra, M. et al.
Partner: UNT Libraries Government Documents Department
open access

A Proposal to Search for Charmed Particle Production Near Threshold

Description: We propose to search for charmed particle production thresholds by looking for anomalies in the ratio of K{sup -}/{pi}{sup -} production at P{sub T} {approx} 1 GeV/c as the incident energy is varied. Any anomalous behavior will be further investigated using a two arm effective mass spectrometer.
Date: November 1, 1974
Creator: Gross, D.; Nitz, D.; Olsen, S.; U., /Rochester; Abe, K.; Bomberowitz, R. et al.
Partner: UNT Libraries Government Documents Department
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Confined excitons, phonons and their interactions in Ge nanocrystals embedded in SiO2

Description: The authors report the resonant Raman scattering of the optical phonon in Ge nanocrystals with radius ranging from 2 to 5 nm. They have observed the effect of quantum confinement on both the optical phonon and the E{sub 1} exciton. The confinement energy of the E{sub 1} exciton has been explained within the effective mass approximation.
Date: December 31, 2000
Creator: Teo, K. L.; Kwok, S. H. & Yu, P. Y.
Partner: UNT Libraries Government Documents Department
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Flow Properties of Superfluid Systems of Fermions

Description: The nonspherically symmetric solutions to the Bardeen-Cooper-Schrieffer theory are given a physical interpretation in terms of an anisotropic fluid model. These solutions have been used previously to predict a phase transition in liquid by He{sup 3} by Emery and Sessler and Anderson, Morel, Brueckner, and Soda. An investigation of the flow properties of such systems is made that involves the calculation of the effective mass for flow in a straight channel and the moment of inertia of a cylindri… more
Date: May 16, 1960
Creator: Glassgold, A. E. & Sessler, A. M.
Partner: UNT Libraries Government Documents Department
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Revised Proposal to Search for Heavy Resonances

Description: During October 1974, we submitted a most timely proposal to search for narrow, heavy resonances by measuring the effective mass spectrum of {pi}{pi}, {pi}K, KK, {pi}p, Kp and {bar p}p pairs. The subsequent discovery of a heavy, narrow resonance at SLAC and BNL caused much excitement and raised many new questions. In part, this may have been the reason why our proposal (No. 357) did not receive the consideration we feel it strongly deserved. We therefore resubmit our proposal, with additional cl… more
Date: December 1, 1974
Creator: Jovanovic, D.; Lundy, R.; Finley, D.; Loeffler, F.; Shibata, E.; Stanfield, K. et al.
Partner: UNT Libraries Government Documents Department
open access

MSW without matter

Description: We examine the effects of a scalar field, coupled only to neutrinos, on oscillations among weak interaction current eigenstates. The existence of a real scalar field is manifested as effective masses for the neutrino mass3 eigenstates, the same for F, as for v. Under some conditions, this can lead to a vanishing of {delta}m{sup 2}, giving rise to MSW-like effects. We present an idealized example and show that it may be possible to resolve the apparent discrepancy in spectra required by reproces… more
Date: September 1, 1996
Creator: Goldman, T.; McKellar, B.H.J. & Stephneson, G.J. Jr.
Partner: UNT Libraries Government Documents Department
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Band anticrossing in dilute nitrides

Description: Alloying III-V compounds with small amounts of nitrogen leads to dramatic reduction of the fundamental band-gap energy in the resulting dilute nitride alloys. The effect originates from an anti-crossing interaction between the extended conduction-band states and localized N states. The interaction splits the conduction band into two nonparabolic subbands. The downward shift of the lower conduction subband edge is responsible for the N-induced reduction of the fundamental band-gap energy. The ch… more
Date: December 23, 2003
Creator: Shan, W.; Yu, K. M.; Walukiewicz, W.; Wu, J.; Ager, J. W., III & Haller, E. E.
Partner: UNT Libraries Government Documents Department
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Approach for Selection of Rayleigh Damping Parameters Used for Time History Analysis

Description: Nonlinearities, whether geometric or material, need to be addressed in seismic analysis. One good analysis method that can address these nonlinearities is direct time integration with Rayleigh damping. Modal damping is the damping typically specified in seismic analysis Codes and Standards. Modal damping is constant for all frequencies where Rayleigh damping varies with frequency. An approach is proposed here for selection of Rayleigh damping coefficients to be used in seismic analyses that are… more
Date: July 1, 2009
Creator: Spears, R. E. & Jensen, S. R.
Partner: UNT Libraries Government Documents Department
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Comparison of quantum confinement effects between quantum wires and dots

Description: Dimensionality is an important factor to govern the electronic structures of semiconductor nanocrystals. The quantum confinement energies in one-dimensional quantum wires and zero-dimensional quantum dots are quite different. Using large-scale first-principles calculations, we systematically study the electronic structures of semiconductor (including group IV, III-V, and II-VI) surface-passivated quantum wires and dots. The band-gap energies of quantum wires and dots have the same scaling with … more
Date: March 30, 2004
Creator: Li, Jingbo & Wang, Lin-Wang
Partner: UNT Libraries Government Documents Department
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Coexistence of Two- and Three-dimensional Shubnikov-de Haas Oscillations in Ar^+ -irradiated KTaO_3

Description: We report the electron doping in the surface vicinity of KTaO{sub 3} by inducing oxygen-vacancies via Ar{sup +}-irradiation. The doped electrons have high mobility (> 10{sup 4} cm{sup 2}/Vs) at low temperatures, and exhibit Shubnikov-de Haas oscillations with both two- and three-dimensional components. A disparity of the extracted in-plane effective mass, compared to the bulk values, suggests mixing of the orbital characters. Our observations demonstrate that Ar{sup +}-irradiation serves as … more
Date: May 16, 2012
Creator: Harashima, S.; Bell, C.; Kim, M.; Yajima, T.; Hikita, Y. & Hwang, H.Y.
Partner: UNT Libraries Government Documents Department
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Search for exotic baryons in 800-GeV pp ---> p Xi+- pi+- X

Description: The authors report the results of a high-statistics, sensitive search for narrow baryon resonances decaying to {Xi}{sup -}{pi}{sup -}, {Xi}{sup -}{pi}{sup +}, {bar {Xi}}{sup +}{pi}{sup +}. The only resonances observed are the well known {Xi}{sup 0}(1530) and {bar {Xi}}{sup 0}(1530). No evidence is found for a state near 1862 MeV, previously reported by NA49[11]. At the 95% confidence level, we find the upper limit for the production of a Gaussian enhancement with {sigma} = 7.6 MeV in the {Xi}{s… more
Date: July 1, 2005
Creator: Christian, D. C.; Felix, J.; Gottschalk, E. E.; Hartouni, E. P.; Knapp, B. C.; Kreisler, M. N. et al.
Partner: UNT Libraries Government Documents Department
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Band anticrossing in highly mismatched semiconductor alloys

Description: The basic theoretical aspects of the band anticrossing effects in highly electronegativity-mismatched semiconductor alloys are reviewed. The many-impurity Anderson model treated in the coherent potential approximation is applied to the semiconductor alloys, in which metallic anion atoms are partially substituted by atoms of a highly electronegative element. Analytical solutions for the Green's function describe dispersion relations and state broadening effects for the restructured conduction ba… more
Date: July 26, 2002
Creator: Walukiewicz, W.
Partner: UNT Libraries Government Documents Department
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Photoemission in Strongly Correlated Crystalline F-Electron Systems: A Need for a New Approach

Description: The unusual properties of heavy fermion (or heavy electron) materials have sparked an avalanche of research over the last two decades in order to understand the basic phenomena responsible for these properties. Photoelectron spectroscopy (often referred to as PES in the following sections), the most direct measurement of the electronic structure of a material, should in principle be able to shed considerable light on this matter. In general the distinction between a localized and a band-like st… more
Date: December 1, 1998
Creator: Arko, A. J.; Joyce, J. J. & Sarrao, J.
Partner: UNT Libraries Government Documents Department
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The Energy Gap in Nuclear Matter

Description: The magnitude of the energy gap in nuclear matter associated with a highly correlated ground state of the type believed to be important in the theory of superconductivity has been evaluated theoretically. The integral equation of Cooper, Mills, and Sessler is linearized and transformed into a form suitable for numerical solution. The energy gap, calculated by using an appropriate single-particle potential and the Gammel-Thaler two-body potential, is found to be a very strong function of the den… more
Date: January 31, 1960
Creator: Emery, V. J. & Sessler, A. M.
Partner: UNT Libraries Government Documents Department
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Conduction band mass determinations for n-type InGaAs/InAlAs single quantum wells

Description: The authors report the measurement of the conduction band mass in n-type single 27-ML-wide InGaAs/InAlAs quantum well lattice matched to InP using two methods: (1) Magnetoluminescence spectroscopy and (2) far-infrared cyclotron resonance. The magnetoluminescence method utilizes Landau level transitions between 0 and 14 T at 1.4 K. The far infrared cyclotron resonance measurements were made at 4.2 K and to fields as large up to 18 T. The 2D-carrier density N{sub 2D} = 3 {times} 10{sup 11} cm{sup… more
Date: May 1, 1998
Creator: Jones, E. D.; Reno, J. L.; Kotera, Nobuo & Wang, Y.
Partner: UNT Libraries Government Documents Department
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Equation of state of hadronic matter with dibaryons in an effective quark model

Description: The equation of state of symmetric nuclear matter with the inclusion of non-strange dibaryons is studied. They pay special attention to the existence of a dibaryon condensate at zero temperature. These calculations have been performed in an extended quark-meson coupling model with density-dependent parameters, which takes into account the finite size of nucleons and dibaryons. A first-order phase-transition to pure dibaryon matter has been found. The corresponding critical density is strongly d… more
Date: June 1, 1998
Creator: Aguirre, R. & Schvellinger, M.
Partner: UNT Libraries Government Documents Department
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A study of parameters useful for describing plasma-opening switches

Description: Plasma opening switches (POS) have been used continually and studied since their introduction in 1975. During that period they have performed well for prepulse suppression and sharpening the front of the power pulse. Their use for long conduction time and rapid opening to stand off high voltage in the same POS has met with very limited success. There has been a large theoretical effort involving models and particle-in-cell simulations (PICS), but the connection between theory and experiment has… more
Date: September 1, 1998
Creator: Mendel, C. W., Jr.; Seidel, D. B. & Rosenthal, S. E.
Partner: UNT Libraries Government Documents Department
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Synthesis of cadmium telluride quantum wires and the similarity of their band gaps to those of equidiameter cadmium telluride quantum dots

Description: High-quality colloidal CdTe quantum wires having purposefully controlled diameters in the range of 5-11 nm are grown by the solution-liquid-solid (SLS) method, using Bi-nanoparticle catalysts, cadmium octadecylphosphonate and trioctylphosphine telluride as precursors, and a TOPO solvent. The wires adopt the wurtzite structure, and grow along the [002] direction (parallel to the c axis). The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to… more
Date: July 11, 2008
Creator: Wang, Lin-Wang; Sun, Jianwei; Wang, Lin-Wang & Buhro, William E.
Partner: UNT Libraries Government Documents Department
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Single particle wavefunction localizations in bulged CdSenanowires

Description: Using atomistic empirical pseudopotentials, we havecalculated the electronic structures of CdSe nanowires with a bulgedarea. The localized state wavefunctions and their binding energies arecalculated, and their dependences on the bulged area shape are analyzed.We find that both the binding energy and the wavefunction localizationstrongly depend on the bulged area shape, with the most compact shapeproduces the largest binding energy and strongest wavefunctionlocalization. We also find that the t… more
Date: July 2, 2006
Creator: Zhao, Zhengji; Wang, Lin-Wang & Wu, Fengmin
Partner: UNT Libraries Government Documents Department
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Predicting dissolution patterns in variable aperture fractures: 1. Development and evaluation of an enhanced depth-averaged computational model

Description: Water-rock interactions within variable-aperture fractures can lead to dissolution of fracture surfaces and local alteration of fracture apertures, potentially transforming the transport properties of the fracture over time. Because fractures often provide dominant pathways for subsurface flow and transport, developing models that effectively quantify the role of dissolution on changing transport properties over a range of scales is critical to understanding potential impacts of natural and ant… more
Date: April 21, 2006
Creator: Detwiler, R L & Rajaram, H
Partner: UNT Libraries Government Documents Department
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Supercritical Stability, Transitions, and (Pseudo)tachyons

Description: Highly supercritical strings (c >> 15) with a time-like linear dilaton provide a large class of solutions to string theory, in which closed string tachyon condensation is under control (and follows the worldsheet renormalization group flow). In this note we analyze the late-time stability of such backgrounds, including transitions between them. The large friction introduced by the rolling dilaton and the rapid decrease of the string coupling suppress the back-reaction of naive instabiliti… more
Date: January 3, 2007
Creator: Aharony, Ofer & Silverstein, Eva
Partner: UNT Libraries Government Documents Department
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Electronic Structure of Germanium Nanocrystal Films Probed with Synchrotron Radiation

Description: The fundamental structure--property relationship of semiconductor quantum dots has been investigated. For deposited germanium nanocrystals strong quantum confinement effects have been determined with synchrotron radiation based x-ray absorption and photoemission techniques. The nanocrystals are condensed out of the gas phase with a narrow size distribution and subsequently deposited in situ onto various substrates. The particles are crystalline in the cubic phase with a structurally disordered … more
Date: May 1, 2002
Creator: Bostedt, C
Partner: UNT Libraries Government Documents Department
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