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Articles 1 - 18 of 18
Full-Text Articles in Entire DC Network
Tunable Optical Delay In Doppler-Broadened Cesium Vapor, Monte D. Anderson
Tunable Optical Delay In Doppler-Broadened Cesium Vapor, Monte D. Anderson
Theses and Dissertations
Variable-delay tunable optical delay line or optical buffers are critical for the development of all-optical networks components as well as interferometry and analytic instruments. Recent research on slow light may hold the key for the development of the first practical tunable optical delay device. In this research the linear dispersion delay effects in an alkali vapor. The hyperfine relaxation observations present insight into the complex bleach wave dynamics during a high-intensity pulsed pump in DPAL systems.
Generalized Ellipsometry On Sculptured Thin Films Made By Glancing Angle Deposition, Daniel Schmidt
Generalized Ellipsometry On Sculptured Thin Films Made By Glancing Angle Deposition, Daniel Schmidt
Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research
In this thesis, physical properties of highly optically and magnetically anisotropic metal sculptured thin films made by glancing angle deposition are presented. Predominantly, the determination of optical and magneto-optical properties with spectroscopic generalized Mueller matrix ellipsometry and homogenization approaches is discussed. Nomenclatures are proposed to unambiguously identify the sculptured thin film geometry.
Generalized ellipsometry, a non-destructive optical characterization technique, is employed to determine geometrical structure and anisotropic dielectric properties of highly spatially coherent three-dimensionally nanostructured thin films in the spectral range from 400 to 1700 nm. The analysis of metal slanted columnar thin films (F1-STFs) deposited at glancing angle ( …
Underway And Moored Methods For Improving Accuracy In Measurement Of Spectral Particulate Absorption And Attenuation, Wayne H. Slade, Emmanuel Boss, Giorgio Dall'olmo, M. Rois Langner, James Loftin, Michael J. Behrenfeld, Collin Roesler, Toby K. Westberry
Underway And Moored Methods For Improving Accuracy In Measurement Of Spectral Particulate Absorption And Attenuation, Wayne H. Slade, Emmanuel Boss, Giorgio Dall'olmo, M. Rois Langner, James Loftin, Michael J. Behrenfeld, Collin Roesler, Toby K. Westberry
Earth and Oceanographic Science Faculty Work
Optical sensors have distinct advantages when used in ocean observatories, autonomous platforms, and on vessels of opportunity, because of their high-frequency measurements, low power consumption, and the numerous established relationships between optical measurements and biogeochemical variables. However, the issues of biofouling and instrument stability over time remain complicating factors when optical instruments are used over periods longer than several days. Here, a method for obtaining calibration-independent measurements of spectral particle absorption and attenuation is presented. Flow-through optical instrumentation is routinely diverted through a large-surface area 0.2-μm cartridge filter, allowing for the calculation of particle optical properties by differencing temporally adjacent …
Refractive Index Dynamics Of Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Refractive Index Dynamics Of Quantum Dot Based Waveguide Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Guillaume Huyet, Et. Al.
Physical Sciences Publications
The refractive index dynamics of InAs/GaAs quantum dot based waveguide absorbers is studied using heterodyne pump-probe measurements. Absorption reduction due to the pump can be accompanied by either positive or negative refractive index changes depending on the wavelength used. This change in sign of the phase amplitude coupling can be understood by considering the atomlike nature of the quantum dot transitions involved.
On Using The Color-Magnitude Diagram Morphology Of M67 To Test Solar Abundances, Z. Magic, A. Serenelli, A. Weiss, B. Chaboyer
On Using The Color-Magnitude Diagram Morphology Of M67 To Test Solar Abundances, Z. Magic, A. Serenelli, A. Weiss, B. Chaboyer
Dartmouth Scholarship
The open cluster M67 has solar metallicity and an age of about 4 Gyr. The turnoff (TO) mass is close to the minimum mass for which solar metallicity stars develop a convective core during main sequence evolution as a result of the development of hydrogen burning through the CNO cycle. The morphology of the color-magnitude diagram (CMD) of M67 around the TO shows a clear hook-like feature, a direct sign that stars close to the TO have convective cores. VandenBerg et al. investigated the possibility of using the morphology of the M67 TO to put constraints on the solar metallicity, …
Solvothermal Synthesis, Structure And Optical Property Of Nanosized Cosb3 Skutterudite, Latha Kumari, Wenzhi Li, Jiangyu Huang, Paula P. Provencio
Solvothermal Synthesis, Structure And Optical Property Of Nanosized Cosb3 Skutterudite, Latha Kumari, Wenzhi Li, Jiangyu Huang, Paula P. Provencio
Department of Physics
Binary skutterudite CoSb3 nanoparticles were synthesized by solvothermal method. The nanostructuring of CoSb3 material was achieved by the inclusion of various kinds of additives. X-ray diffraction examination indicated the formation of the cubic phase of CoSb3. Structural analysis by transmission electron microscopy analysis further confirmed the formation of crystalline CoSb3 nanoparticles with high purity. With the assistance of additives, CoSb3nanoparticles with size as small as 10 nm were obtained. The effect of the nanostructure of CoSb3on the UV–visible absorption and luminescence was studied. The nanosized CoSb3 skutterudite may find application …
Sn 2010u: A Luminous Nova In Ngc 4214, Roberta M. Humphreys, José L. Prieto, Philip Rosenfield, L. Andrew Helton, Christopher S. Kochanek, K. Z. Stanek, Rubab Khan, Dorota Szczygiel, Karen Mogren, Robert A. Fesen
Sn 2010u: A Luminous Nova In Ngc 4214, Roberta M. Humphreys, José L. Prieto, Philip Rosenfield, L. Andrew Helton, Christopher S. Kochanek, K. Z. Stanek, Rubab Khan, Dorota Szczygiel, Karen Mogren, Robert A. Fesen
Dartmouth Scholarship
The luminosity, light curve, post-maximum spectrum, and lack of a progenitor on deep pre-outburst images suggest that SN 2010U was a luminous, fast nova. Its outburst magnitude is consistent with that for a fast nova using the maximum magnitude-rate of decline relationship for classical novae.
Stirring Up The Pot: Can Cooling Flows In Galaxy Clusters Be Quenched By Gas Sloshing?, J. A. A. Zuhone, M. Markevitch, R. E. Johnson
Stirring Up The Pot: Can Cooling Flows In Galaxy Clusters Be Quenched By Gas Sloshing?, J. A. A. Zuhone, M. Markevitch, R. E. Johnson
Dartmouth Scholarship
X-ray observations of clusters of galaxies reveal the presence of edges in surface brightness and temperature, known as "cold fronts." In relaxed clusters with cool cores, these commonly observed edges have been interpreted as evidence for the "sloshing" of the core gas in the cluster's gravitational potential. Such sloshing may provide a source of heat to the cluster core by mixing hot gas from the cluster outskirts with the cool-core gas. Using high-resolution N-body/Eulerian hydrodynamic simulations, we model gas sloshing in galaxy clusters initiated by mergers with subclusters. The simulations include merger scenarios with gas-filled and gasless subclusters. The …
Influence Of Ni Nanoparticle On The Morphology And Growth Of Interfacial Intermetallic Compounds Between
A.S. Md Abdul Haseeb
TiO2 thin films were deposited on unheated and heated glass substrates at an elevated sputtering pressure of 3 Pa by radio frequency (RF) reactive magnetron sputtering. TiO2 films deposited at room temperature were annealed in air for 1 h at various temperatures ranging from 300 to 600 °C. The structural and optical properties of the thin films were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet-visible-near infrared (UV-VIS-NIR) spectrophotometry. XRD results show that as-grown and post-annealed TiO2 films have anatase crystal structure. Higher substrate and annealing temperatures result in a slight increase of crystallinity. TiO2 …
Application Of Luminescence Sensors In Oxygen Diffusion Measurement And Study Of Luminescence Enhancement/Quenching By Metallic Nanoparticles, Sanchari Chowdhury
Application Of Luminescence Sensors In Oxygen Diffusion Measurement And Study Of Luminescence Enhancement/Quenching By Metallic Nanoparticles, Sanchari Chowdhury
USF Tampa Graduate Theses and Dissertations
The first part of this dissertation deals with the application of a luminescence quenching method to measure diffusion and permeation coefficients of oxygen in polymers. Most luminescence oxygen sensors do not follow linearity of the Stern-Volmer (SV) equation due to heterogeneity of luminophore in the polymer matrix, thus the complexity of data analysis is increased. To circumvent this limitation, inverted fluorescence microscopy is utilized in this work to investigate the SV response of the sensors at the micron-scale. In these diffusion experiments, oxygen concentration is measured by luminescence changes in regions with high SV constants and good linearity. Thus, we …
Core Gas Sloshing In Abell 1644, Ryan E. Johnson, Maxim Markevitch, Gary A. Wegner, Christine Jones, William R. Forman
Core Gas Sloshing In Abell 1644, Ryan E. Johnson, Maxim Markevitch, Gary A. Wegner, Christine Jones, William R. Forman
Dartmouth Scholarship
We present an analysis of a 72 ks Chandra observation of the double cluster Abell 1644 (z = 0.047). The X-ray temperatures indicate that the masses are M 500 = (2.6 ± 0.4) × 1014 h –1 M ☉ for the northern sub-cluster and M 500 = (3.1 ± 0.4) × 1014 h –1 M ☉ for the southern, main cluster. We identify a sharp edge in the radial X-ray surface brightness of the main cluster, which we find to be a cold front, with a jump in temperature of a factor of ~3. This edge possesses …
Estimating The Maritime Component Of Aerosol Optical Depth And Its Dependency On Surface Wind Speed Using Satellite Data, Y. Lehahn, I. Koren, E. Boss, Y. Ben-Ami, O. Altaratz
Estimating The Maritime Component Of Aerosol Optical Depth And Its Dependency On Surface Wind Speed Using Satellite Data, Y. Lehahn, I. Koren, E. Boss, Y. Ben-Ami, O. Altaratz
Marine Sciences Faculty Scholarship
Six years (2003-2008) of satellite measurements of aerosol parameters from the Moderate Resolution Imaging Spectroradiometer (MODIS) and surface wind speeds from Quick Scatterometer (QuikSCAT), the Advanced Microwave Scanning Radiometer (AMSR-E), and the Special Sensor Microwave Imager (SSM/I), are used to provide a comprehensive perspective on the link between surface wind speed and marine aerosol optical depth over tropical and subtropical oceanic regions. A systematic comparison between the satellite derived fields in these regions allows to: (i) separate the relative contribution of wind-induced marine aerosol to the aerosol optical depth; (ii) extract an empirical linear equation linking coarse marine aerosol optical …
Metallization Of Nanofilms In Strong Adiabatic Electric Fields, Maxim Durach, Anastasia Rusina, Matthias F. Kling, Mark I. Stockman
Metallization Of Nanofilms In Strong Adiabatic Electric Fields, Maxim Durach, Anastasia Rusina, Matthias F. Kling, Mark I. Stockman
Maxim Durach
We introduce an effect of metallization of dielectric nanofilms by strong, adiabatically varying electric fields. The metallization causes optical properties of a dielectric film to become similar to those of a plasmonic metal (strong absorption and negative permittivity at low optical frequencies). This is a quantum effect, which is exponentially size-dependent, occurring at fields on the order of 0.1 V/Å and pulse durations ranging from ∼1 fs to ∼10 ns for a film thickness of 3–10 nm.
Investigations On Tio2 And Ag Based Single And Multilayer Films For Window Glazings
Investigations On Tio2 And Ag Based Single And Multilayer Films For Window Glazings
A.S. Md Abdul Haseeb
In this investigation, TiO2 and Ag based single and multilayer-films were deposited on microscope glass slides with varying individual layer thicknesses by radio-frequency reactive magnetron sputtering. Prior to multilayer development, single layers of Ag and TiO2 were deposited and characterized. All the films were prepared at an elevated pressure of 3 Pa at room temperature. It was found that single layer of TiO2 showed anatase polycrystalline structure. It also exhibited high visible transmittance of above 80% and higher refractive index of 2.31 at a wavelength of 550 nm. The indirect optical band gap of the TiO2 films was estimated as …
Influence Of Substrate Temperatures On Structural, Morphological And Optical Properties Of Rf-Sputtered Anatase Tio 2 Films
A.S. Md Abdul Haseeb
In this investigation, TiO 2 thin films were deposited on glass substrates at varying substrate temperatures from room temperature to 300 °C by radio-frequency (RF) magnetron sputtering at an elevated sputtering pressure of 3 Pa. As-deposited TiO 2 films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), field emission Auger electron microscopy (FEAES), and UV-visible-NIR spectrophotometry. The XRD results reveal that all the as-deposited films possessing the anatase structure and crystallinity of TiO 2 films appears to deteriorate slightly at higher substrate temperatures. The crystallite size of the as-deposited films at different substrate temperatures …
Chemical Bath Deposition And Characterization Of Cu_2o-Cu_Xs Thin Films, D. D. O. Eya
Chemical Bath Deposition And Characterization Of Cu_2o-Cu_Xs Thin Films, D. D. O. Eya
Turkish Journal of Physics
Cu_2O-Cu_xS thin films have been deposited on glass substrate by chemical bath deposition technique. The films were obtained by depositing Copper Sulphide (Cu_xS) on Copper (I) Oxide (Cu_2O) and then Cu_2O on Cu_xS. The peak solar transmittance across the thin films were found to be
Optical Properties Of Photopolymer Layers Doped With Aluminophosphate Nanocrystals, Elsa Leite, Tzvetanka Babeva, E Ng, Vincent Toal, Svetlana Mintova, Izabela Naydenova
Optical Properties Of Photopolymer Layers Doped With Aluminophosphate Nanocrystals, Elsa Leite, Tzvetanka Babeva, E Ng, Vincent Toal, Svetlana Mintova, Izabela Naydenova
Articles
The optical properties of photopolymer layers consisting of an acrylamide–based matrix and microporous aluminophosphate nanocrystals of AEI- type are investigated. The compatibility of the photopolymer doped with the nanoparticles is studied. The surface and volume properties of the layers with different levels of doping with microporous nanocrystals are characterized. The effective refractive indices and absorption coefficients of the doped photopolymer layers are determined and used to calculate the refractive index and porosity of pure AEI nanoparticles used as dopants. Volume transmission gratings were recorded in the doped photopolymer layers at different spatial frequencies. By spatial monitoring of the characteristic Raman …
Structure And Optical Properties Of Cuals_2 Thin Films Prepared Via Chemical Bath Deposition, Tariq Alwan, Mushtak Jabbar
Structure And Optical Properties Of Cuals_2 Thin Films Prepared Via Chemical Bath Deposition, Tariq Alwan, Mushtak Jabbar
Turkish Journal of Physics
CuAlS_2 thin films of thicknesses 118 \pm 5 nm were deposited on glass substrates using chemical bath deposition technique. The details of the preparation method are well described. The method is relatively simple and is easily controlled and sufficient to produce large area and good adherence to the substrate films. Effect of annealing temperature T_a on the structure, and optical properties of CuAlS_2 films were investigated. The structures of the films were studied by X-ray diffraction and FTIR spectrophotometer. The optical properties of the films were ascertained by UV-VIS spectrophotometer (wavelengths ranging between 300 and 900 nm). The optical transmittance …