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in subjects: "Reflectivity"  
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Development of extreme ultraviolet and soft x-ray multilayer optics for scientific studies with femtosecond/attosecond sources

Description: The development of multilayer optics for extreme ultraviolet (EUV) radiation has led to advancements in many areas of science and technology, including materials studies, EUV lithography, water window microscopy, plasma imaging, and orbiting solar physics imaging. Recent developments in femtosecond and attosecond EUV pulse generation from sources such as high harmonic generation lasers, combined with the elemental and chemical specificity provided by EUV radiation, are opening new opportunities… more
Date: May 21, 2009
Creator: Aquila, Andrew Lee
Partner: UNT Libraries Government Documents Department
open access

Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

Description: Surface sensitive synchrotron X-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface at room temperature. To control surface charge density, lipids, dihexadecyl hydrogen-phosphate (DHDP) and dimysteroyl phosphatidic acid (DMPA), were spread as monolayer materials at the air/water interface, containing CsI at various concentrations. Five decades in bulk concentrations (CsI) are investigated, demonstrating that the interfacial dist… more
Date: August 15, 2009
Creator: Bu, Wei
Partner: UNT Libraries Government Documents Department
open access

Recombination and propagation of quasiparticles in cuprate superconductors

Description: Rapid developments in time-resolved optical spectroscopy have led to renewed interest in the nonequilibrium state of superconductors and other highly correlated electron materials. In these experiments, the nonequilibrium state is prepared by the absorption of short (less than 100 fs) laser pulses, typically in the near-infrared, that perturb the density and energy distribution of quasiparticles. The evolution of the nonequilibrium state is probed by time resolving the changes in the optical re… more
Date: May 20, 2004
Creator: Gedik, Nuh
Partner: UNT Libraries Government Documents Department
open access

Dynamic ray tracing and its application in triangulated media

Description: Hale and Cohen (1991) developed software to generate two-dimensional computer models of complex geology. Their method uses a triangulation technique designed to support efficient and accurate computation of seismic wavefields for models of the earth`s interior. Subsequently, Hale (1991) used this triangulation approach to perform dynamic ray tracing and create synthetic seismograms based on the method of Gaussian beams. Here, I extend this methodology to allow an increased variety of ray-theore… more
Date: July 1993
Creator: Rueger, A.
Partner: UNT Libraries Government Documents Department
open access

Computational Study and Analysis of Structural Imperfections in 1D and 2D Photonic Crystals

Description: Dielectric reflectors that are periodic in one or two dimensions, also known as 1D and 2D photonic crystals, have been widely studied for many potential applications due to the presence of wavelength-tunable photonic bandgaps. However, the unique optical behavior of photonic crystals is based on theoretical models of perfect analogues. Little is known about the practical effects of dielectric imperfections on their technologically useful optical properties. In order to address this issue, a fin… more
Date: June 1, 2005
Creator: Maskaly, Karlene Rosera
Partner: UNT Libraries Government Documents Department
open access

Near-ground cooling efficacies of trees and high-albedo surfaces

Description: Daytime summer urban heat islands arise when the prevalence of dark-colored surfaces and lack of vegetation make a city warmer than neighboring countryside. Two frequently-proposed summer heat island mitigation measures are to plant trees and to increase the albedo (solar reflectivity) of ground surfaces. This dissertation examines the effects of these measures on the surface temperature of an object near the ground, and on solar heating of air near the ground. Near-ground objects include peopl… more
Date: May 1, 1997
Creator: Levinson, R.M.
Partner: UNT Libraries Government Documents Department
open access

Reflectivity of plasmas created by high-intensity, ultra-short laser pulses

Description: Experiments were performed to characterize the creation and evolution of high-temperature (T{sub e}{approximately}100eV), high-density (n{sub e}>10{sup 22}cm{sup {minus}3}) plasmas created with intense ({approximately}10{sup 12}-10{sup 16}W/cm{sup 2}), ultra-short (130fs) laser pulses. The principle diagnostic was plasma reflectivity at optical wavelengths (614nm). An array of target materials (Al, Au, Si, SiO{sub 2}) with widely differing electronic properties tested plasma behavior over a lar… more
Date: June 1, 1994
Creator: Gold, David Michael
Partner: UNT Libraries Government Documents Department
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