128 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Raman Spectroscopy"  
Results: 1 - 24 next
open access

Investigation of Structure and Properties of Low Temperature Deposited Diamond-Like Carbon Films

Description: Electrodeposition is a novel method for fabrication of diamond-like carbon (DLC) films on metal substrates. In this work, DLC was electrochemically deposited on different substrates based on an anodic oxidation cyclization of acetylene in liquid ammonia. Successfully anodic deposition was carried out for DLC onto nickel substrate at temperatures below -40°C. Comparative studies were performed on a series of different carbon sources (acetylene, sodium acetylide, and a mixture of acetylene and… more
Date: August 2004
Creator: Pingsuthiwong, Charoendee
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
open access

Raman Study of Lead Zirconate Titanate Under Uniaxial Stress

Description: The authors used micro-Raman spectroscopy to monitor the ferroelectric (FE) to antiferroelectric (AFE) phase transition in PZT ceramic bars during the application of uniaxial stress. They designed and constructed a simple loading device, which can apply sufficient uniaxial force to transform reasonably large ceramic bars while being small enough to fit on the mechanical stage of the microscope used for Raman analysis. Raman spectra of individual grains in ceramic PZT bars were obtained as the s… more
Date: April 1, 2000
Creator: Tallant, David R.; Simpson, Regina L.; Grazier, J. Mark; Zeuch, David H.; Olson, Walter R. & Tuttle, Bruce A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Measurements and characterization - Electro-optical characterization

Description: This brochure presents the capabilities that the Measurements and Characterization Division has in Electro-Optical Characterization, in which a variety of spectroscopy, ellipsometry, and capacitance techniques are used to probe the fundamental electrical and optical properties of solid-state materials.
Date: March 16, 2000
Creator: Cook, G.
Item Type: Refine your search to only Book
Partner: UNT Libraries Government Documents Department
open access

Raman study of phonons in Sr{sub 3}Mn{sub 2}O{sub 6.54} and Sr{sub 3}Mn{sub 2}O{sub 7} layered manganites

Description: Polycrystalline Sr{sub 3}Mn{sub 2}O{sub 6.54} and Sr{sub 3}Mn{sub 2}O{sub 7} layered manganites were studied at room temperature using Raman spectroscopy. While the phonon spectrum of the stoichiometric Sr{sub 3}Mn{sub 2}O{sub 7} sample is consistent with the group theoretical analysis for the 14/mm structure, three additional modes are observed in the phonon spectrum of the oxygen deficient Sr{sub 3}Mn{sub 2}O{sub 6.54} sample. Based on an analysis of the temperature dependence of the Raman sp… more
Date: April 27, 2000
Creator: Guedes, I.; Mitchell, J. F.; Argyriou, D. & Grimsditch, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Towards Chip Scale Liquid Chromatography and High Throughput Immunosensing

Description: This work describes several research projects aimed towards developing new instruments and novel methods for high throughput chemical and biological analysis. Approaches are taken in two directions. The first direction takes advantage of well-established semiconductor fabrication techniques and applies them to miniaturize instruments that are workhorses in analytical laboratories. Specifically, the first part of this work focused on the development of micropumps and microvalves for controlled f… more
Date: September 21, 2000
Creator: Ni, J.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Analysis of Surface Leaching Processes in Vitrified High-Level Nuclear Wastes Using In-Situ Raman Imaging and Atomistic Modeling - Final Report

Description: The in situ analysis of surface conditions of vitrified nuclear wastes can provide an important check of the burial status of radioactive objects without risk of radiation exposure. Raman spectroscopy was initially chosen as the most promising method for testing the surface conditions of glasses undergoing chemical corrosion, and was used extensively during the first year. However, it was determined that infrared reflection spectroscopy was better suited to this particular need and was used for… more
Date: April 24, 2001
Creator: Simmons, Joseph H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

MICROMECHANICS IN CONTINOUS GRAPHITE FIBER/EPOXY COMPOSITES DURING CREEP

Description: Micro Raman spectroscopy and classic composite shear-lag models were used to analyze the evolution with time of fiber and matrix strain/stress around fiber breaks in planar model graphite fiber-epoxy matrix composites. Impressive agreements were found between the model predictions and the experimental results. The local matrix creep leads to an increase in the load transfer length around the break under a constant load. This increases the chance of fiber breakage in the neighboring intact fiber… more
Date: February 1, 2001
Creator: ZHOU, C. & AL, ET
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A high-resolution large-acceptance analyzer for X-ray fluorescence and Raman spectroscopy

Description: A newly designed multi-crystal X-ray spectrometer and its applications in the fields of X-ray fluorescence and X-ray Raman spectroscopy are described. The instrument is based on 8 spherically curved Si crystals, each with a 3.5 inch diameter form bent to a radius of 86 cm. The crystals are individually aligned in the Rowland geometry capturing a total solid angle of 0.07 sr. The array is arranged in a way that energy scans can be performed by moving the whole instrument, rather than scanning ea… more
Date: August 2, 2001
Creator: Bergmann, Uwe & Cramer, Stephen P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Calcium-Dependent Conformation of a Heme and Fingerprint Peptide of the Di-Heme Cytochrome c Peroxidase from Paracoccus Pantotrophus

Description: The structural changes in the heme macrocycle and substituents caused by binding of Ca{sup 2+} to the diheme cytochrome c peroxidase from Paracoccuspantotrophus were clarified by resonance Raman spectroscopy of the inactive filly oxidized form of the enzyme. The changes in the macrocycle vibrational modes are consistent with a Ca{sup 2+}-dependent increase in the out-of-plane distortion of the low-potential heme, the proposed peroxidatic heme. Most of the increase in out-of-plane distortion occ… more
Date: December 18, 2000
Creator: Pauleta, Sofia R.; Lu, Yi; Goodhew, Celia F.; Moura, Isabel; Pettigrew, Graham W. & Shelnutt, John A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fiber-Optic Laser Raman Spectroscopy Sensor

Description: The Defense Programs Plant Directed Research and Development Program sponsored the optimization and interface of a fiber-optic Raman sensor as a complementary technique to mass spectrometry currently used in the Tritium Facility for measuring hydrogen isotopes. This sensor will provide real-time feedback while reducing the sample load for off-line gas analysis by the Tritium mass spectrometers. The compact Raman system incorporates a 488 nanometer laser system, spectrometer and detector along w… more
Date: September 15, 2003
Creator: Ziegler, K. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Rapid Ultrasensitive Chemical-Fingerprint Detection of Chemical and Biochemical Warfare Agents

Description: Vibrational spectra can serve as chemical fingerprints for positive identification of chemical and biological warfare molecules. The required speed and sensitivity might be achieved with surface-enhanced Raman spectroscopy (SERS) using nanotextured metal surfaces. Systematic and reproducible methods for preparing metallic surfaces that maximize sensitivity have not been previously developed. This work sought to develop methods for forming high-efficiency metallic nanostructures that can be inte… more
Date: December 1, 2002
Creator: ASHBY, CAROL I.; SHEPODD, TIMOTHY J.; YELTON, WILLIAM G. & MURON, DAVID J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Raman phonons in RPO{sub 4} crystals.

Description: Orthophosphates formed by elements in the first half of the lanthanide transition series (La, Pr, Nd, Sm, Eu and Gd) are structural analogs to the monoclinic mineral monazite. This mineral is characterized by an almost unique combination of properties that make its synthetic forms attractive as possible hosts for the long-term storage of actinide wastes. Crystals of lanthanide orthophosphates were grown by dissolving and by reacting lanthanide oxides in molten lead pyrophosphate at high tempera… more
Date: May 15, 2002
Creator: Paschoal, C. W. A.; Ayala, A. P.; Guedes, I.; Loong, C.-K. & Boatner, L. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

ET-based mixed-donor CT salt : [ET/MET/MT](ReO{sub 4}).

Description: A new charge-transfer(CT) salt of the ET-based mixed-donor, [ET/MET/MT](ReO{sub 4}), has been prepared by the electrocrystallization. This salt has been revealed to be a 1:1 salt by x-ray structure analysis and micro-Raman spectroscopy. EPR measurement gives g = 2.007 and {_}H{sub pp} = 9.18G at 300K. It shows a semiconducting behavior with E{sub g} = 92-110 meV depending on the samples.
Date: August 21, 2002
Creator: Noh, D.-Y.; Han, Y.-K.; Kang, W.; Kang, H. & Geiser, U.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Friction-induced structural transformations of DLC coatings under different atmospheres.

Description: The structural transformations that occur in diamondlike carbon coatings with increasing hydrogen content have been investigated by Raman spectroscopy, transmission electron microscopy, electron diffraction, and electron-energy-loss spectroscopy. Friction tests were performed with uncoated steel balls against coated substrates at contact stresses of 1 GPa in ambient air (relative humidity = 30 - 40%), dry air (relative humidity < 1%), and dry nitrogen (< 1%). The lowest friction coefficie… more
Date: June 27, 2002
Creator: Sanchez-Lopez, J. C.; Erdemir, A.; Donnet, C. & Rojas, T. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Large-Scale Production of Single-Walled Carbon Nanotubes using Ultrafast Pulses from an FEL

Description: We report very high production rates of SWNTs from carbon vapor produced by ultrafast ({approx}0.5 ps) pulsed infrared radiation from the Free Electron Laser (FEL) at Thomas Jefferson National Accelerator (Jlab). To harness the high average power ({approx} 1 kW average power) of this FEL beam, a new vaporization geometry was developed in which the laser radiation impinges on the sidewall of a translating and spinning, carbon rod. Using only 30% of the available FEL average power at a wavelength… more
Date: January 1, 2002
Creator: Jordan, Kevin; Eklund, P. C.; Pradhan, B. K.; Kim, U. J.; Fischer, J. E. & Smith, M. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Friction-induced structural transformations of DLC coatings under different atmospheres.

Description: The structural transformations that occur in diamondlike carbon coatings with increasing hydrogen content have been investigated by Raman spectroscopy, transmission electron microscopy, electron diffraction, and electron-energy-loss spectroscopy. Friction tests were performed with uncoated steel balls against coated substrates at contact stresses of 1 GPa in ambient air (relative humidity = 30 - 40%), dry air (relative humidity < 1%), and dry nitrogen (< 1%). The lowest friction coefficie… more
Date: March 21, 2002
Creator: Sanchez-Lopez, J. C.; Erdemir, A.; Donnet, C. & Rojas, T. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Pathway and Surface Mechanism Studies of 1,3-butadiene Selective Oxidation Over Vanadium-Molybdenum-Oxygen Catalysts

Description: The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9-14 m{sup 2}/g, and compositions were within the solid solution regime, i.e. below 15.0 mol % MoO{sub 3}/(MoO{sub 3} + V{sub 2}O{sub 5}). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V{sup +4} and were further reduced in 1,3-butadiene oxidati… more
Date: May 27, 2002
Creator: Schroeder, William David
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

New Metal Niobate and Silicotitanate Ion Exchangers: Development and Characterization

Description: This project is a continuing EMSP project entitled ''New Silicotitanate Waste Forms: Development and Characterization.'' In our original study, the phase selection and chemical durability of silicotitanates (including commercially available IE-911) as a function of temperature (500 to 1000 C) was fully characterized by a combination of techniques including XRD, TEM, SEM, NMR, Raman spectroscopy, XAFS, XANES, and by thermodynamic studies. In addition, work on this program led to new discoveries … more
Date: June 1, 2002
Creator: Su, Yali; Nenoff, Tina M. & Navrotsky, Alexandra
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Interfacial phenomena on selected cathode materials

Description: We have carried out a series of surface studies of selected cathode materials. Instrumental techniques such as Raman microscopy, surface enhanced Raman spectroscopy (SERS), and atomic force microscopy were used to investigate the cathode surfaces. The goal of this study was to identify detrimental processes which occur at the electrode/electrolyte interface and can lead to electrode degradation and failure during cycling and/or storage at elevated temperatures.
Date: June 22, 2001
Creator: Kostecki, Robert; Matsuo, Yoshiaki & McLarnon, Frank
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

FTIR Laboratory in Support of the PV Program

Description: The Fourier Transform Infrared Spectroscopy (FTIR) Laboratory supports the Solar Energy Technologies Program through the measurement and characterization of solar energy-related materials and devices. The FTIR technique is a fast, accurate, and reliable method for studying molecular structure and composition. This ability to identify atomic species and their bonding environment is a powerful combination that finds use in many research and development efforts. A brief overview of the technical a… more
Date: January 1, 2005
Creator: Keyes, B. M.; Gedvilas, L. M.; Bhattacharya, R.; Xu, Y.; Li, X. & Wang, Q.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A New Method for In-situ Characterization of Important Actinides and Technetium Compounds via Fiberoptic Surface Enhanced Raman Spectroscopy (SERS)

Description: This project serves to fill information gap through the development of a novel surface-enhanced Raman scattering (SERS) spectroscopy to selectively and sensitively monitor and characterize the chemical speciation of radionuclides at trace levels. The SERS technique permits both of these measurements to be made simultaneously, and results in significant improvement over current methods in reducing time of analysis, cost, and sample manipulation. Our overall goal is (a) to develop a scientific ba… more
Date: June 15, 2003
Creator: Dai, Sheng & Gu, B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A New Method for In-situ Characterization of Important Actinides and Technetium Compounds via Fiberoptic Surface Enhanced Raman Spectroscopy (SERS)

Description: This project serves to fill information gap through the development of a novel surface-enhanced Raman scattering (SERS) spectroscopy to selectively and sensitively monitor and characterize the chemical speciation of radionuclides at trace levels. The SERS technique permits both of these measurements to be made simultaneously, and results in significant improvement over current methods in reducing time of analysis, cost, and sample manipulation. Our overall goal is (a) to develop a scientific ba… more
Date: June 24, 2004
Creator: Dai, Sheng & Gu, B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
Back to Top of Screen