Search NASA⌕ Search

SEARCH · Search NASA

Results for “Spectroscopy, Fourier Transform Infrared”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Pyridoxine deficiency affects biomechanical properties of chick tibial bone

The mechanical integrity of bone is dependent on the bone matrix, which is believed to account for the plastic deformation of the tissue, and the mineral, which is believed to account for the elastic deformation. The validity of this model is shown in this study based on analysis of the bones of vitamin B6-deficient and vitamin B6-replete chick bones. In this model, when B6-deficient and control animals are compared, vitamin B6 deficiency has no effect on the mineral content or composition of cortical bone as measured by ash weight (63 +/- 6 vs. 58 +/- 3); mineral to matrix ratio of the FTIR spectra (4.2 +/- 0.6 vs. 4.5 +/- 0.2), line-broadening analyses of the X-ray diffraction 002 peak (beta 002 = 0.50 +/- 0.1 vs. 0.49 +/- 0.01), or other features of the infrared spectra. In contrast, collagen was significantly more extractable from vitamin B6-deficient chick bones (20 +/- 2% of total hydroxyproline extracted vs. 10 +/- 3% p < or = 0.001). The B6-deficient bones also contained an increased amount of the reducible cross-links DHLNL, dehydro-dihydroxylysinonorleucine, (1.03 +/- 0.07 vs. 0.84 +/- 0.13 p < or = 0.001); and a nonsignificant increase in HLNL, dehydro-hydroxylysinonorleucine, (0.51 +/- 0.03 vs. 0.43 +/- 0.03, p < or = 0.10). There were no significant changes in bone length, bone diameter, or area moment of inertia. In four-point bending, no significant changes in elastic modulus, stiffness, offset yield deflection, or fracture deflection were detected. However, fracture load in the B6-deficient animals was decreased from 203 +/- 35 MPa to 151 +/- 23 MPa, p < or = 0.01, and offset yield load was decreased from 165 +/- 9 MPa to 125 +/- 14 MPa, p < or = 0.05. Since earlier histomorphometric studies had demonstrated that the B6-deficient bones were osteopenic, these data suggest that although proper cortical bone mineralization occurred, the alterations of the collagen resulted in changes to bone mechanical performance.

Non-NASA Center↗
NASA NTRS1995

Infrared spectroscopy of matrix-isolated polycyclic aromatic hydrocarbon cations. 2. The members of the thermodynamically most favorable series through coronene

Gaseous, ionized polycyclic aromatic hydrocarbons (PAHs) are thought to be responsible for a very common family of interstellar infrared emission bands. Here the near- and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene:phenanthrene, pyrene, benzo[e]pyrene, benzo[ghi]perylene, and coronene, are presented to test this hypothesis. For those molecules that have been studied previously (pyrene, pyrene-d10, and coronene), band positions and relative intensities are in agreement. In all of these cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeuteriophenanthrene, pyrene, benzo[ghi]perylene, and coronene cations. With the exception of coronene, the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations, the CC stretching and CH in-plane bending modes give rise to bands that are an order of magnitude stronger than those of the neutral species, and the CH out-of-plane bends produce bands that are 5-20 times weaker than those of the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed.

NASA Discipline Exobiology↗
NASA NTRS1985

Resin Characterization in Cured Composite Materials

Molecular-level characterization of polymeric matrix resin in cured graphite-reinforced composite materials now determined through analysis of diffuse reflectance (DR) with Fourier Transform Infrared (FTIR) spectroscopy. Improved analytical method based on diffuse reflectance. DR/ FTIR technique successfully applied to analysis of several different composites and adhesives impossible to analyze by conventional methods.

Young, P. R.↗
NASA NTRS1986

Emission FTIR analyses of thin microscopic patches of jet fuel residues deposited on heated metal surfaces

The relationship of fuel stability to fuel composition and the development of mechanisms for deposit formation were investigated. Fuel deposits reduce heat transfer efficiency and increase resistance to fuel flow and are highly detrimental to aircraft performance. Infrared emission Fourier transform spectroscopy was chosen as the primary method of analysis because it was sensitive enough to be used in-situ on tiny patches of monolayers or of only a few molecular layers of deposits which generally proved completely insoluble in any nondestructive solvents. Deposits of four base fuels were compared; dodecane, a dodecane/tetralin blend, commercial Jet A fuel, and a broadened-properties jet fuel particularly rich in polynuclear aromatics. Every fuel in turn was provided with and without small additions of such additives as thiophene, furan, pyrrole, and copper and iron naphthenates.

Lauer, J. L.↗
NASA NTRS1985

Photovoltaics module interface: General purpose primers

The interfacial chemistry established between ethylene vinyl acetate (EVA) and the aluminized back surface of commercial solar cells was observed experimentally. The technique employed is called Fourier Transform Infrared (FTIR) spectroscopy, with the infrared signal being reflected back from the aluminum surface through the EVA film. Reflection infrared (IR) spectra are given and attention is drawn to the specific IR peak at 1080/cm which forms on hydrolytic aging of the EVA/aluminum system. With this fundamental finding, and the workable experimental techniques, candidate silane coupling agents are employed at the interface, and their effects on eliminating or slowing hydrolytic aging of the EVA/aluminum interface are monitored.

Boerio, J.↗
NASA NTRS1988

Measurement of HO2 and other trace gases in the stratosphere using a high resolution far-infrared spectrometer at 28 KM

The major events and results to date of the ongoing program of measuring stratospheric composition by the technique of far-infrared Fourier-transform spectroscopy from a balloon-borne platform are reviewed. The highlights of this period were the two balloon flight campaigns which were performed at Palestine, Texas, both of which produced large amounts of scientifically useful data.

Traub, Wesley A.↗
NASA NTRS1988

Infrared absorption study of neutron-transmutation-doped germanium

Using high-resolution far-infrared Fourier transform absorption spectroscopy and Hall effect measurements, the evolution of the shallow acceptor and donor impurity levels in germanium during and after the neutron transmutation doping process was studied. The results show unambiguously that the gallium acceptor level concentration equals the concentration of transmutated Ge-70 atoms during the whole process indicating that neither recoil during transmutation nor gallium-defect complex formation play significant roles. The arsenic donor levels appear at full concentration only after annealing for 1 h at 450 C. It is shown that this is due to donor-radiation-defect complex formation. Again, recoil does not play a significant role.

Park, I. S.↗
NASA NTRS1989

Frequency and intensity analysis of the nu3, nu4, and nu6 bands of formaldehyde

The infrared spectra of the nu3, nu4, and nu6 bands of formaldehyde in the region from 890/cm to 1580/cm have been obtained at high resolution using tunable diode laser and Fourier transform-infrared spectroscopy. The transition frequencies have been analyzed using a Hamiltonian including terms through sextic in centrifugal distortion and including five interstate vibration-rotation coupling terms. Excited-state pure rotational transitions are also included in the data, and their frequencies are reproduced well. Individual measured line intensities are used to determine dipole derivatives and band strengths using the fully coupled, asymmetric top eigenvectors.

Reuter, D. C.↗
NASA NTRS1991

Study of balloon and thermal control material degradation aboard LDEF

The initial results of analysis performed on a number of polymeric materials which were exposed aboard the Long Duration Exposure Facility (LDEF) are discussed. These materials include two typical high altitude balloon films (a polyester and a polyethylene) and silver-backed Teflon from thermal control blanket samples. The techniques used for characterizing changes in mechanical properties, chemical structure and surface morphology include Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy, and dynamic mechanical analysis.

Letton, Alan↗
NASA NTRS1993

Spectroscopic studies of model polar stratospheric cloud films

Fourier transform infrared (FTIR) spectroscopy has been used to study nitric-acid/ice films representative of type I polar stratospheric clouds (PSCs). These studies reveal that in addition to amorphous nitric acid/ice mixtures, there are three stable stoichiometric hydrates of nitric acid: nitric-acid monohydrate (NAM), dihydrate (NAD), and trihydrate (NAT). We also observe two distinct crystalline forms of the trihydrate, which we denote alpha- and beta-NAT. These two forms appear to differ in their concentration of crystalline defects, but not in their chemical composition. In addition to probing the composition of type I PSCs, we have also used FTIR spectroscopy to study the interaction of HCl with model PSC films. In this work we find that for HCl pressures in the range 10 exp -5 to 10 exp -7 Torr, HCl is taken up by ice at 155 K to form a thin layer of HCl.6H2O. At 193 K, the uptake of HCl by ice was consistent with less than or equal to monolayer coverage. Uptake of HCl by alpha and beta-NAT at 175 K was also consistent with less than or equal to monolayer coverage.

Tolbert, Margaret A.↗
NASA NTRS1994

Growth of nitric acid hydrates on thin sulfuric acid films

Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-3 x 10(exp -4) Torr H2O and 1-2.5 x 10(exp -6) Torr HNO3) and subjected to cooling and heating cycles. Fourier Transform Infrared (FTIR) spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

Iraci, Laura T.↗
NASA NTRS1995

FTIR studies of low temperature sulfuric acid aerosols

Sub-micrometer sized sulfuric acid H2SO4 particles were generated using a constant output atomizer source. The particles were then exposed to water vapor before being injected into a low temperature cell. Multipass transmission Fourier Transformation Infrared (FTIR) spectroscopy was used to determine the phase and composition of the aerosols as a function of time for periods of up to five hours. Binary H2SO4H2O aerosols with compositions from 35 to 95 wt % H2SO4 remained liquid for over 3 hours at room temperatures ranging from 189-240 K. These results suggest that it is very difficut to freeze SSAs via homogeneous nucleation. Attempts to form aerosols more dilute than 35 wt % H2SO4 resulted in ice formation.

Anthony, S. E.↗
NASA NTRS1995

A New Antiwear Additive/Surface Pretreatment for PFPE Liquid Lubricants

Pin-on-disk tribology experiments were conducted on a perfluoroalkylelher (PFPE) liquid lubricant with and without a new PFPE lubricant antiwear additive material, a silane. It was found that the silane provided moderate improvement in the antiwear performance of the PFPE lubricant when applied to the metallic surface as a surface coating or when added to the PFPE as a dispersion (emulsion). Slightly better results were obtained by using the combination of a surface coating and an emulsion of the silane. The silane emulsions or coatings did not affect the friction properties of the lubricant. Micro-Fourier transformation infrared (muFTIR) spectroscopy analysis was performed to study silane transfer films and the degradation of the PFPE. The silane was found to mitigate degradation of the PFPE which may have been the major reason for the improved antiwear performance observed.

Morales, Wilfredo↗
NASA NTRS1997

Development of Processing Techniques for Advanced Thermal Protection Materials

Thermal Protection Materials Branch (TPMB) has been involved in various research programs to improve the properties and structural integrity of the existing aerospace high temperature materials. Specimens from various research programs were brought into the analytical laboratory for the purpose of obtaining and refining the material characterization. The analytical laboratory in TPMB has many different instruments which were utilized to determine the physical and chemical characteristics of materials. Some of the instruments that were utilized by the SJSU students are: Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX), X-ray Diffraction Spectrometer (XRD), Fourier Transform-Infrared Spectroscopy (FTIR), Ultra Violet Spectroscopy/Visible Spectroscopy (UV/VIS), Particle Size Analyzer (PSA), and Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). The above mentioned analytical instruments were utilized in the material characterization process of the specimens from research programs such as: aerogel ceramics (I) and (II), X-33 Blankets, ARC-Jet specimens, QUICFIX specimens and gas permeability of lightweight ceramic ablators. In addition to analytical instruments in the analytical laboratory at TPMB, there are several on-going experiments. One particular experiment allows the measurement of permeability of ceramic ablators. From these measurements, physical characteristics of the ceramic ablators can be derived.

Selvaduray, Guna↗
NASA NTRS1999

Diagnostic for Plasma Enhanced Chemical Vapor Deposition and Etch Systems

In order to meet NASA's requirements for the rapid development and validation of future generation electronic devices as well as associated materials and processes, enabling technologies ion the processing of semiconductor materials arising from understanding etch chemistries are being developed through a research collaboration between Stanford University and NASA-Ames Research Center, Although a great deal of laboratory-scale research has been performed on many of materials processing plasmas, little is known about the gas-phase and surface chemical reactions that are critical in many etch and deposition processes, and how these reactions are influenced by the variation in operating conditions. In addition, many plasma-based processes suffer from stability and reliability problems leading to a compromise in performance and a potentially increased cost for the semiconductor manufacturing industry. Such a lack of understanding has hindered the development of process models that can aid in the scaling and improvement of plasma etch and deposition systems. The research described involves the study of plasmas used in semiconductor processes. An inductively coupled plasma (ICP) source in place of the standard upper electrode assembly of the Gaseous Electronics Conference (GEC) radio-frequency (RF) Reference Cell is used to investigate the discharge characteristics and chemistries. This ICP source generates plasmas with higher electron densities (approximately 10(exp 12)/cu cm) and lower operating pressures (approximately 7 mTorr) than obtainable with the original parallel-plate version of the GEC Cell. This expanded operating regime is more relevant to new generations of industrial plasma systems being used by the microelectronics industry. The motivation for this study is to develop an understanding of the physical phenomena involved in plasma processing and to measure much needed fundamental parameters, such as gas-phase and surface reaction rates. species concentration, temperature, ion energy distribution, and electron number density. A wide variety of diagnostic techniques are under development through this consortium grant to measure these parameters. including molecular beam mass spectrometry (MBMS). Fourier transform infrared (FTIR) spectroscopy, broadband ultraviolet (UV) absorption spectroscopy, a compensated Langmuir probe. Additional diagnostics. Such as microwave interferometry and microwave absorption for measurements of plasma density and radical concentrations are also planned.

Cappelli, Mark A.↗
NASA NTRS2000

Deterrent Concentration Measurement with FTIR and Subsequent Ballistic Performance in Medium Caliber Propellant

To meet ballistic requirements, medium and small caliber propellants use deterrent coatings to obtain burn rate progressivity. The required amount and distribution of deterrent varies between gun systems, propellant types, and often between lots. Micro Fourier Transform Infrared (FTIR) spectroscopy was used to measure deterrent gradients in RP36 propellants coated with methyl centralite (MC) at different deterrent levels and different processing conditions. The aromatic C-C bonds at 1496 cm(exp -1) wavenumber were used to monitor the deterrent profiles through the grain. Deterrent gradients measured with FTIR spectroscopy were then used to estimate burn rate gradients in the deterred grains. Burn rates were calculated from literature models and from closed bomb data of RP36 containing uniform deterrent concentration. Finally, the burn rate gradients were input into an IBHFG2 model of a 200 cc-closed bomb. The early flame spreading portion of the closed bomb ballistic cycle (0 to 0.2 P/Pmax) was roughly modeled by dividing the charge up into five propellant decks and igniting them at different times in the ballistic cycle. Pressure traces and vivacity curves from closed bomb shots were compared to predictions. In addition to the burn rate gradient, the closed bomb pressure trace was heavily dependent on ignition and flame spread. These two phenomena were not readily distinguishable from one another in deterred grains. The same RP-36 propellant was shot in a 25 mm M793TP round which was again modeled with IBHVG2. Peak pressure and muzzle velocity were accurately modeled when erosive burning effects were empirically factored into the model.

Furrow, Keith W.↗
NASA NTRS2001

Functionalization of Carbon Nanotubes using Atomic Hydrogen

We have investigated the irradiation of multi walled and single walled carbon nanotubes (SWNTs) with atomic hydrogen. After irradiating the SWNT sample, a band at 2940/cm (3.4 microns) that is characteristic of the C-H stretching mode is observed using Fourier transform infrared (FTIR) spectroscopy. Additional confirmation of SWNT functionalization is tested by irradiating with atomic deuterium. A weak band in the region 1940/cm (5.2 micron) to 2450/cm (4.1 micron) corresponding to C-D stretching mode is also observed in the FTIR spectrum. This technique provides a clean gas phase process for the functionalization of SWNTs, which could lead to further chemical manipulation and/or the tuning of the electronic properties of SWNTs for nanodevice applications.

Khare, Bishun N.↗
NASA NTRS2003

Thermal and Chemical Characterization of Composite Materials. MSFC Center Director's Discretionary Fund Final Report, Project No. ED36-18

The purpose of this research effort was to: (1) provide a concise and well-defined property profile of current and developing composite materials using thermal and chemical characterization techniques and (2) optimize analytical testing requirements of materials. This effort applied a diverse array of methodologies to ascertain composite material properties. Often, a single method of technique will provide useful, but nonetheless incomplete, information on material composition and/or behavior. To more completely understand and predict material properties, a broad-based analytical approach is required. By developing a database of information comprised of both thermal and chemical properties, material behavior under varying conditions may be better understood. THis is even more important in the aerospace community, where new composite materials and those in the development stage have little reference data. For example, Fourier transform infrared (FTIR) spectroscopy spectral databases available for identification of vapor phase spectra, such as those generated during experiments, generally refer to well-defined chemical compounds. Because this method renders a unique thermal decomposition spectral pattern, even larger, more diverse databases, such as those found in solid and liquid phase FTIR spectroscopy libraries, cannot be used. By combining this and other available methodologies, a database specifically for new materials and materials being developed at Marshall Space Flight Center can be generated . In addition, characterizing materials using this approach will be extremely useful in the verification of materials and identification of anomalies in NASA-wide investigations.

Stanley, D. C.↗