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Synthesis and Infrared Spectra of Substituted Phthalimidines

Description: A number of N-substituted-3-hydroxy-3-phenylphthal-imidines and some of the isomeric amides have been prepared in order to study changes in the infrared spectra of these compounds due to structural changes in the molecule, particularly with reference to a hydroxyl band at 3.0µ and a carbonyl band at 5.75µ.
Date: June 1962
Creator: Reeves, Linda R.
Partner: UNT Libraries

Infrared Spectroscopy of Carbohydrates: A Review of the Literature

Description: Report presenting of survey of the literature on the infrared spectroscopy of carbohydrates in order to assemble and systematize information in this field. Discusses principles and instrumentation, sampling techniques, comparison of samples, and the interpretation of the spectra. In addition, examples are discussed of the use of infrared spectra for qualitative and quantitative purposes and in the determination of structure. Special techniques are briefly described.
Date: June 1968
Creator: Tipson, R. Stuart
Partner: UNT Libraries Government Documents Department

Computational studies of the potential energy surface for O(¹D) + H₂S: Characterization of pathways involving H₂SO, HOSH, and H₂OS

Description: Article on computational studies of the potential energy surface for O(¹D) + H₂S and the characterization of pathways involving H₂SO, HOSH, and H₂OS.
Date: December 1, 1994
Creator: Goumri, Abdellatif; Rocha, John-David Ray; Laakso, Dianna; Smith, C. E. & Marshall, Paul
Partner: UNT College of Arts and Sciences

Determination of the electronic structure of bilayer graphene from infrared spectroscopy results

Description: We present an experimental study of the infrared conductivity, transmission, and reflection of a gated bilayer graphene and their theoretical analysis within the Slonczewski-Weiss-McClure (SWMc) model. The infrared response is shown to be governed by the interplay of the interband and the intraband transitions among the four bands of the bilayer. The position of the main conductivity peak at thecharge-neutrality point is determined by the interlayer tunneling frequency. The shift of this peak as a function of the gate voltage gives information about less known parameters of the SWMc model such as those responsible for the electron-hole and sublattice asymmetries. These parameter values are shown to be consistent with recent electronic structure calculations for the bilayer graphene and the SWMc parameters commonly used for the bulk graphite.
Date: November 12, 2008
Creator: Zhang, L. M.; Li, Z. Q.; Basov, D. N.; Fogler, M. M.; Hao, Z. & Martin, Michael C.
Partner: UNT Libraries Government Documents Department

PREPARATION AND PROPERTIES OF THE ACTINIDE BOROHYDRIDES: Pa(BH4)4, Np(BH4)4, AND Pu(BH4)4

Description: The actinide borohydrides, Pa(BH{sub 4}){sub 4}, Np(BH{sub 4}){sub 4}, and Pu(BH{sub 4}){sub 4} have been synthesized. Pa(BH{sub 4}){sub 4}, a solid at 20{sup o} is isostructural with U(BH{sub 4}){sub 4}. Np(BH{sub 4}){sub 4} and Pu(BH{sub 4}){sub 4} are volatile liquids at 20{sup o} but are isostructural at low temperatures and crystallize in a tetragonal crystal structure type. The metal atom distances indicate the solid is monomeric and similar to Zr(BH{sub 4}){sub 4}. Preliminary Raman spectra on solid Np(BH{sub 4}){sub 4} support this idea. Gas-phase infrared spectra indicate theNp and Pu atoms in these compounds are surrounded by four BH{sub 4}{sup -} groups in a tetrahedral array with each B coordinated via 3 hyrodgen bridge bonds to the metal atom.
Date: October 1, 1977
Creator: Banks, R.H; Edelstein, N.M; Rietz, R.R.; Templeton, David H. & Zalkin, Allan
Partner: UNT Libraries Government Documents Department

Enhanced sensitivity for hyperspectral infrared chemical detection

Description: The sensitivity of imaging, hyperspectral, passive remote sensors in the long-wavelength infrared (LWIR) spectral region is currently limited by the ability to achieve an accurate, time-invariant, pixel-to-pixel calibration of the elements composing the Focal Plane Array (FPA). Pursuing conventional techniques to improve the accuracy of the calibration will always be limited by the trade-off between the time required to collect calibration data of improved precision and the drift in the pixel response that occurs on a timescale comparable to the calibration time. This paper will present the results from a study of a method to circumvent these problems. Improvements in detection capability can be realized by applying a quick, repetitive dither of the field of view (FOV) of the imager (by a small angular amount), so that radiance/spectral differences between individual target areas can be measured by a single FPA pixel. By performing this difference measurement repetitively both residual differences in the pixel-to-pixel calibration and l/f detector drift noise can effectively be eliminated. In addition, variations in the atmosphere and target scene caused by the motion of the sensor platform will cause signal drifts that this technique would be able to remove. This method allows improvements in sensitivity that could potentially scale as the square root of the observation time.
Date: January 1, 2001
Creator: Jacobson, P. L. (Phillip L.); Petrin, R. R. (Roger R.); Koskelo, A. C. (Aaron C.); Quick, C. R. (Charles R.) & Romero, J. J. (Jerry J.)
Partner: UNT Libraries Government Documents Department

Final Report on LDRD project 130784 : functional brain imaging by tunable multi-spectral Event-Related Optical Signal (EROS).

Description: Functional brain imaging is of great interest for understanding correlations between specific cognitive processes and underlying neural activity. This understanding can provide the foundation for developing enhanced human-machine interfaces, decision aides, and enhanced cognition at the physiological level. The functional near infrared spectroscopy (fNIRS) based event-related optical signal (EROS) technique can provide direct, high-fidelity measures of temporal and spatial characteristics of neural networks underlying cognitive behavior. However, current EROS systems are hampered by poor signal-to-noise-ratio (SNR) and depth of measure, limiting areas of the brain and associated cognitive processes that can be investigated. We propose to investigate a flexible, tunable, multi-spectral fNIRS EROS system which will provide up to 10x greater SNR as well as improved spatial and temporal resolution through significant improvements in electronics, optoelectronics and optics, as well as contribute to the physiological foundation of higher-order cognitive processes and provide the technical foundation for miniaturized portable neuroimaging systems.
Date: September 1, 2009
Creator: Speed, Ann Elizabeth; Spahn, Olga Blum & Hsu, Alan Yuan-Chun
Partner: UNT Libraries Government Documents Department

Laser-induced reactions in a deep UV resist system: Studied with picosecond infrared spectroscopy

Description: One of the most technologically important uses of organic photochemistry is in the imaging industry where radiation-sensitive organic monomers and polymers are used in photoresists. A widely-used class of compounds for imaging applications are diazoketones; these compounds undergo a photoinduced Wolff rearrangement to form a ketene intermediate which subsequently hydrolyses to a base-soluble, carboxylic acid. Another use of organic molecules in polymer matrices is for dopant induced ablation of polymers. As part of a program to develop diagnostics for laser driven reactions in polymer matrices, we have investigated the photoinduced decomposition of 5-diazo-2,2-dimethyl-1,3-dioxane-4,6-dione (5-diazo Meldrum`s acid, DM) in a PMMA matrix using picosecond infrared spectroscopy. In particular, irradiation of DM with a 60 ps 266 nm laser pulse results in immediate bleaching of the diazo infrared band ({nu} = 2172 cm{sup -1}). Similarly, a new band appears within our instrument response at 2161 cm{sup -1} (FWHM = 29 cm{sup -1}) and is stable to greater than 6 ns.; we assign this band to the ketene photoproduct of the Wolff rearrangement. Using deconvolution techniques we estimate a limit for its rate of formation of {tau} < 20 ps. The linear dependence of the absorbance change with the pump power (266 nm) even above the threshold of ablation suggest that material ejection take place after 6ns.
Date: December 31, 1995
Creator: Lippert, T.; Koskelo, A. & Stoutland, P.O.
Partner: UNT Libraries Government Documents Department

Carbon implanted in optical grade fused silica: annealing effects in reducing and oxidizing atmospheres

Description: Carbon is implanted into fused silica with doses of 1, 3, 6, 10X10{sup 16} ions/cm{sup 2}. Infrared spectroscopy identified the formation of CO and CO{sub 2} molecules in the implanted glasses. Relations among concentrations of carbon dioxide, carbon monoxide, and carbon doses are established by the infrared measurements. Annealing under different atmospheres have dramatic effects on CO and CO{sub 2} concentrations.
Date: January 1, 1997
Creator: Tsung, Y.S.; Mu, R.; Ueda, A.; Henderson, D.O.; Wang, P.W.; White, C.W. et al.
Partner: UNT Libraries Government Documents Department

Evaluating open-path FTIR spectrometer data using different quantification methods, libraries, and background spectra obtained under varying environmental conditions

Description: Studies were performed to evaluate the accuracy of open-path Fourier Transform Infrared (OP-FTIR) spectrometers using a 35 foot outdoor exposure chamber in Pittsboro, North Carolina. Results obtained with the OP-FTIR spectrometer were compared to results obtained with a reference method (a gas chromatograph equipped with a flame ionization detector, GC-FID). Concentration results were evaluated in terms of the mathematical methods and spectral libraries used for quantification. In addition, the research investigated the effect on quantification of using different backgrounds obtained at various times during the day. The chemicals used in this study were toluene, cyclohexane, and methanol; and these were evaluated over the concentration range of 5-30 ppm.
Date: December 31, 1995
Creator: Tomasko, M.S.
Partner: UNT Libraries Government Documents Department

Low severity coal liquefaction promoted by cyclic olefins. Quarterly report, October 1996--December 1996

Description: The goal of this research is to develop a methodology for analyzing the reactivity of cyclic olefins in situ in a high temperature and high pressure infrared cell. The reactivities of naphthalene, decalin, tetralin, isotetralin, 1,2-dihydronaphthalene and 1,4-dihydronaphthalene have been studied at 230{degrees}C under ambient pressure and under 500 psig blankets of both nitrogen and hydrogen.
Date: June 1, 1997
Creator: Curtis, C.W.
Partner: UNT Libraries Government Documents Department

Inelastic neutron scattering study of the (O{sub 4}H{sub 4}) substitution in garnet

Description: Inelastic scattering data have been collected at incident neutron energies of 50, 150, 300 and 600 meV for hydrogarnet [Sr{sub 3}Al{sub 2}(O{sub 4}H{sub 4}){sub 3}], a model compound for silicate hydrogarents found in the Earth`s crust and mantle. The vibrational spectrum is characterized by a relatively sharp O-H stretch at {approximately}460 meV, which is consistent with the weak O...H bond ({approximately}2.65 {angstrom}) and other complex features in the 20-100 meV region. The mode assignment for isostructural grosslar and the infrared spectra for hydrogarnet were used as a basis for the intreperation of many of the neutron spectral features.
Date: July 14, 1997
Creator: Lager, G.A.; Nipko, J.C. & Loong, C.K.
Partner: UNT Libraries Government Documents Department

Size, shape, and crystallinity of luminescent structures in oxidized Si nanoclusters and H-passivated porous Si

Description: Near-edge and extended x-ray absorption fine structure measurements from a wide variety of H-passivated porous Si samples and oxidized Si nanocrystals, combined with electron microscopy, ir-absorption, {alpha}-recoil, and luminescence emission data, provide a consistent structural picture of the species responsible for the luminescence observed in these systems. For luminescent porous Si samples peaking in the visible region, i. e., {le}700nm, their mass-weighted-average structures are determined here to be particles - not wires, whose short-range character is crystalline - not amorphous, and whose dimensions - typically <15 {angstrom} - are significantly smaller than previously reported or proposed. These results depend only on sample luminescence behavior, not on sample preparation details, and thus have general implications in describing the mechanism responsible for visible luminescence in porous silicon. New results are also presented which demonstrate that the observed luminescence is unrelated to either the photo-oxidized Si species in porous Si or the interfacial suboxide species in the Si nanocrystals.
Date: November 1, 1994
Creator: Schuppler, S.; Marcus, M.A.; Xie, Y.H.; Harris, T.D.; Brown, W.L.; Chabal, Y.J. et al.
Partner: UNT Libraries Government Documents Department

Raman and infrared studies of the Sharp 890 cm{sup -1} mode in organic superconductors.

Description: Raman and infrared spectra of several organic superconductors are presented, showing some unusual behaviors of a sharp line at 890 cm{sup {minus}} in both spectra. These include a frequency shift below T{sub c}, a positive deuterium isotope shift, frequency softening at low temperatures and sensitivity to lattice superstructure. It is proposed that either the ion or the neutral molecule has a distortion with a strong v{sub 60}(B{sub 3g}) mode component.
Date: November 28, 2000
Creator: Eldridge, J. E.; Lin, Y.; Schlueter, J. A.; Wang, H. H. & Kini, A. M.
Partner: UNT Libraries Government Documents Department

Synthetic infrared spectra for correlation spectroscopy

Description: As a first step toward the development of a new remote sensing technique that the authors call holographic correlation spectroscopy, they demonstrate that diffractive optics can be used to synthesize the infrared spectra of real compounds. In particular, they have designed, fabricated, and characterized a diffractive element that successfully reproduces the major features f the spectrum of gaseous HF in the region between 3,600 cm{sup {minus}1} and 4,300 cm{sup {minus}1}. The reflection-mode diffractive optic consists of 4,096 lines, each 4.5 {micro}m wide, at 16 discrete depths relative to the substrate (from 0 to 1.2 {micro}m), and was fabricated on a silicon wafer using anisotropic reactive ion-beam etching in a four-mask-level process. The authors envision the use of diffractive elements of this type to replace the cumbersome reference cells of conventional correlation spectroscopy and thereby enable a new class of compact and versatile correlation spectrometers.
Date: December 1, 1997
Creator: Sinclair, M.B.; Butler, M.A.; Ricco, A.J.; Kravitz, S.H.; Zubrzycki, W.J. & Warren, M.E.
Partner: UNT Libraries Government Documents Department

EXAFS studies of lanthanide coordination in crystalline phosphates and amorphous phytates

Description: As part of the DOE Efficient Separations and Processing Integrated Program, techniques are being developed to stabilize radioactive and hazardous contaminants to prevent their migration from buried wastes. This report is part of a study to immobilize actinide ions in the near-surface environment by reacting them with organophosphorus complexants that decompose to phosphates. Nd and Gd ions were used as models for Pu, Am, and Cm ions; phytic acid was used as the complexant. Solid Nd and Gd phytates were prepared and the coordination characterized by EXAFS.
Date: December 31, 1995
Creator: Morss, L.R.; Schmidt, M.A.J. & Nash, K.L.
Partner: UNT Libraries Government Documents Department

Adaptable Multivariate Calibration Models for Spectral Applications

Description: Multivariate calibration techniques have been used in a wide variety of spectroscopic situations. In many of these situations spectral variation can be partitioned into meaningful classes. For example, suppose that multiple spectra are obtained from each of a number of different objects wherein the level of the analyte of interest varies within each object over time. In such situations the total spectral variation observed across all measurements has two distinct general sources of variation: intra-object and inter-object. One might want to develop a global multivariate calibration model that predicts the analyte of interest accurately both within and across objects, including new objects not involved in developing the calibration model. However, this goal might be hard to realize if the inter-object spectral variation is complex and difficult to model. If the intra-object spectral variation is consistent across objects, an effective alternative approach might be to develop a generic intra-object model that can be adapted to each object separately. This paper contains recommendations for experimental protocols and data analysis in such situations. The approach is illustrated with an example involving the noninvasive measurement of glucose using near-infrared reflectance spectroscopy. Extensions to calibration maintenance and calibration transfer are discussed.
Date: December 20, 1999
Creator: THOMAS,EDWARD V.
Partner: UNT Libraries Government Documents Department

Nonlinear optical studies of organic liquid interfaces

Description: Infrared-visible sum-frequency generation is the only available technique that can generate surface vibrational spectra for liquid interfaces. Several examples from recent studies in our laboratory are used to show how the surface vibrational spectra can yield useful information about structures of liquid surfaces.
Date: July 1, 1995
Creator: Shen, Y.R.
Partner: UNT Libraries Government Documents Department

Use of step scan FT-IR and multivariate curve resolution to understand aging of propellant binder as a function of depth into the polymer material.

Description: A sample of polymeric propellant binder was aged from 0 to 60 days at 95 C and analyzed using FT-IR step scan photoacoustic spectroscopy. This technique has the ability of to obtain spectra of the polymer as a function of depth into the polymer material. Multivariate curve resolution was applied to the spectra data obtained to extract the contributions of the aged and un-aged spectral components from the spectra. It was found that multivariate curve resolution could efficiently separate highly overlapped spectra and yielded insights into the aging process.
Date: January 1, 2003
Creator: Rivera, Dion Arledge & Alam, Mary Kathleen
Partner: UNT Libraries Government Documents Department