Search NASA⌕ Search

SEARCH · Search NASA

Results for “VACUUM SPECTROSCOPY”

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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Nickel hydrogen multicell common pressure vessel battery development update

The technology background and design qualification of the multicell common pressure vessel nickel hydrogen battery are described. The results of full flight qualification, including random vibration at 19.5 g for two minutes in each axis, electrical characterization in a thermal vacuum chamber, and mass spectroscopy vessel leak detection are reviewed and 12.7 cm qualification and 25.4 cm design adaptation are discussed.

Zagrodnik, Jeffrey P.↗
NASA NTRS2010

Total Synthesis of Ionic Liquid Systems for Dissolution of Lunar Simulant

For purposes of Space Resource Utilization, work in the total synthesis of a new ionic liquid system for the extraction of oxygen and metals from lunar soil is studied and described. Reactions were carried out according to procedures found in the chemical literature, analyzed via Thin-Layer Chromatography and 1H Nuclear Magnetic Resonance Spectroscopy and purified via vacuum distillation and rotary evaporation. Upon final analysis via 1H NMR, it was found that while the intermediates of the synthesis had been achieved, unexpected side products were also present. The mechanisms and constraints of the synthesis are described as well as the final results of the project and recommendations for continued study

Sharpe, Robert J.↗
NASA NTRS2006

Accurate VUV Laboratory Measurements of Fe III Transitions for Astrophysical Applications

We report preliminary measurements of Fe III spectra in the 1150 to 2500 A wavelength interval. Spectra have been recorded with an iron-neon Penning discharge lamp (PDL) between 1600 and 2500 A at Imperial College (IC) using high resolution Fourier (FT) transform spectroscopy. These FT spectrometer measurements were extended beyond 1600 A to 1150 A using high-resolution grating spectroscopy at the National Institute of Standards and Technology (NIST). These recorded spectra represent the first radiometrically calibrated measurements of a doubly-ionized iron-group element spectrum combining the techniques of vacuum ultraviolet FT and grating spectroscopy. The spectral range of the new laboratory measurements corresponds to recent HST/STIS observations of sharp-lined B stars and of Eta Carinae. The new improved atomic data can be applied to abundance studies and diagnostics of astrophysical plasmas.

Blackwell-Whitehead, R. J.↗
NASA NTRS1982

Surface chemistry and wear behavior of single-crystal silicon carbide sliding against iron at temperatures to 1500 C in vacuum

X-ray photoelectron and Auger electron spectroscopy analyses and morphological studies of wear and metal transfer were conducted with a single-crystal silicon carbide 0001 surface in contact with iron at various temperatures to 1500 C in a vacuum of 10 to the minus 8th power pascal. The results indicate that below 800 C, carbide-carbon and silicon are primarily seen on the silicon carbide surface. Above 800 C the graphite increases rapidly with increase in temperature. The outermost surficial layer, which consists mostly of graphite and little silicon at temperatures above 1200 C is about 2 nm thick. A thicker layer, which consists of a mixture of graphite, carbide, and silicon is approximately 100 nm thick. The closer the surface sliding temperature is to 800 C, the more the metal transfer produced. Above 800 C, there was a transfer of rough, discontinuous, and thin iron debris instead of smooth, continuous and thin iron film which was observed to transfer below 800 C. Two kinds of fracture pits were observed on the silicon carbide surface: (1) a pit with a spherical asperity; and (2) multiangular shaped pits.

Miyoshi, K.↗
NASA NTRS1985

Observation of adsorbate-induced surface states by elastic electron tunneling spectroscopy

Electronic structure induced by adsorbates at the interface of Al/AlOx/Au tunnel junctions has been observed by elastic electron tunneling spectroscopy. Strong structures appearing in the tunneling spectra above approximately 1 eV after exposure to I, Hg, Bi, and organohalides, have been interpreted in terms of adsorbate-induced surface states. The spectroscopic capabilities of elastic electron tunneling spectroscopy may be useful in the area of chemical detection. In the broader sense, the observation of adsorbate-induced unoccupied electronic states below the vacuum energy, makes elastic electron tunneling spectroscopy a potentially useful technique for the study of surfaces.

Leduc, H. G.↗
NASA NTRS1981

Integrated material-surface analyzer

These 10 surface-analysis tests can be run without breaking vacuum: secondary-ion mass spectroscopy, ion-scattering spectroscopy, electron-stimulated desorption, residual-gas analysis, auger electron spectroscopy, x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, characteristic-electron energy-loss spectroscopy, scanning electron microscope, scanning low-energy electron probe. Quadruple mass spectrometer, used in first 4 tests, serves as electron transfer lens in last 6 tests.

Grunthaner, F. J.↗
NASA NTRS1987

A survey of simulation and diagnostic techniques for hypersonic nonequilibrium flows

The possible means of simulating nonequilibrium reacting flows in hypersonic environments, and the required diagnostic techniques, are surveyed in two categories: bulk flow behavior and determination of chemical rate parameters. Flow visualization of shock shapes for validation of computational-fluid dynamic calculations is proposed. The facilities and the operating conditions necessary to produce the required nonequilibrium conditions, the suitable optical techniques, and their sensitivity requirements, are surveyed. Shock-tubes, shock-tunnels, and ballistic ranges in a wide range of sizes and strengths are found to be useful for this purpose, but severe sensitivity requirements are indicated for the optical instruments, which can be met only by using highly-collimated laser sources. Likewise, for the determination of chemical parameters, this paper summarizes the quantities that need to be determined, required facilities and their operating conditions, and the suitable diagnostic techniques and their performance requirements. Shock tubes of various strengths are found to be useful for this purpose. Vacuum ultraviolet absorption and fluorescence spectroscopy and coherent anti-Stokes Raman spectroscopy are found to be the techniques best suited for the measurements of the chemical data.

Sharma, Surendra P.↗
NASA NTRS1993

Nickel-hydrogen CPV battery update

The multicell common pressure vessel (CPV) nickel hydrogen battery manufactured by Johnson Controls Battery Group, Inc. has completed full flight qualification, including random vibration at 19.5 g for two minutes in each axis, electrical characterization in a thermal vacuum chamber, and mass-spectroscopy vessel leak detection. A first launch is scheduled for late in 1992 or early 1993 by the Naval Research Laboratory (NRL). Specifics of the launch date are not available at this time due to the classified nature of the program. Release of orbital data for the battery is anticipated following the launch.

Jones, Kenneth R.↗
NASA NTRS1993

Comprehensive investigation of HgCdTe metalorganic chemical vapor deposition

The principal objective of this experimental and theoretical research program was to explore the possibility of depositing high quality epitaxial CdTe and HgCdTe at very low pressures through metalorganic chemical vapor deposition (MOCVD). We explored two important aspects of this potential process: (1) the interaction of molecular flow transport and deposition in an MOCVD reactor with a commercial configuration, and (2) the kinetics of metal alkyl source gas adsorption, decomposition and desorption from the growing film surface using ultra high vacuum surface science reaction techniques. To explore the transport-reaction issue, we have developed a reaction engineering analysis of a multiple wafer-in-tube ultrahigh vacuum chemical vapor deposition (UHV/CVD) reactor which allows an estimate of wafer or substrate throughput for a reactor of fixed geometry and a given deposition chemistry with specified film thickness uniformity constraints. The model employs a description of ballistic transport and reaction based on the pseudo-steady approximation to the Boltzmann equation in the limit of pure molecular flow. The model representation takes the form of an integral equation for the flux of each reactant or intermediate species to the wafer surfaces. Expressions for the reactive sticking coefficients (RSC) for each species must be incorporated in the term which represents reemission from a wafer surface. The interactions of MOCVD precursors with Si and CdTe were investigated using temperature programmed desorption (TPD) in ultra high vacuum combined with Auger electron spectroscopy (AES). These studies revealed that diethyltellurium (DETe) and dimethylcadmium (DMCd) adsorb weakly on clean Si(100) and desorb upon heating without decomposing. These precursors adsorb both weakly and strongly on CdTe(111)A, with DMCd exhibiting the stronger interaction with the surface than DETe.

Raupp, Gregory B.↗
NASA NTRS2006

Atomic Oscillator Strengths in the Vacuum Ultraviolet

We have developed techniques to measure branching fractions in the vacuum ultraviolet using diffraction grating spectroscopy and phosphor image plates as detectors. These techniques have been used to measure branching fractions in Fe II that give prominent emission lines in astrophysical objects.

Nave, Gillian↗
NASA NTRS2010

The Thermal Infrared Investigation on Cassini: A Challenge for Laboratory Studies

Slides about the Composite Infrared Spectrometer (CIRS) examine Cassini remote sensing spectral coverage; instrument description; thermal-vacuum testing; mechanical layout; laboratory spectroscopy and Voyager IRIS; composite brightness temperature of Titan; Titan FP1, FP3, and FP4 large average; Titan's atmospheric haze; CIRS values for Titan's atmosphere, isotopic species identified, and molecular parameters.

Jennings, Donald↗
NASA NTRS1980

Polytetrafluoroethylene transfer film studied with X-ray photoelectron spectroscopy

Polytetrafluoroethylene (PTFE) was rubbed against nickel in ultrahigh vacuum at loads up to 3.9 N and speeds up to 94 mm/sec. The transfer film formed on the nickel was analyzed using X-ray phototectron spectroscopy. The film was indistinguishable from bulk PTFE except for the possible presence of a small amount of NiF2. The transfer film was found to be about 1 molecule (0.5 nm) thick under all conditions; but at speeds above 10 mm/sec, there was evidence of bulk transfer in the form of fragments as well. The thickness measurements required a choice among conflicting published values of the inelastic mean free path for electrons in polymers. The values chosen gave internally consistent results.

Wheeler, D. R.↗
NASA NTRS1992

Vacuum ultraviolet absorption in a hydrogen arcjet

Atomic absorption spectroscopy was utilized to measure the ground state atomic hydrogen number density in the plasma produced in a low power hydrogen arcjet. A microwave driven hydrogen plasma was used as the source of radiation resonant with the vacuum ultraviolet Lyman alpha transition. The suitability of this radiation source is discussed. The optical depth of this transition prevented measurements at locations where the ground state atomic hydrogen number density was larger than 3 x 10 exp 19/cu m. These results indicate that other single-photon optical diagnostic techniques are equally ineffective in locations of higher hydrogen number density unless the spectral line shape of the atomic hydrogen absorbers is known.

Manzella, David H.↗
NASA NTRS1991

Ultraviolet spectroscopy of cometary comae

During the past decade, vacuum ultraviolet spectra of over 30 comets have been obtained with the IUE satellite observatory. With few exceptions, the spectra of these comets appear to be similar, with OH and H produced by the photodissociation of water being the dominant species and emissions of C, O, S, CS and CO2(+) usually present. Although signs of variabiity of many kinds in comet spectra appear, the evidence from the UV observations suggests that all comets have the same basic chemical composition and that observed differences are due to evolution and ageing processes. During the 1985-86 apparition of Comet Halley, spectra were also obtained by other spacecraft and by sounding rocket instruments, including a long-slit imaging spectrograph.

Feldman, Paul D.↗
NASA NTRS1978

Experimental Studies of the Formation/Deposition of Sodium Sulfate in/from Combustion Gases

Processes related to the hot corrosion of gas turbine components were examined in two separate investigations. Monochromatic laser light was used to probe condensation onset and condensate film growth (via interference of reflected light) on electrically heated ribbons immersed in seeded, flat flame combustion product gases. Boron trichloride is used as the seed gas in these preliminary experiments conducted to obtain precise measurements of the dew point/deposition rates. Because of the importance of gaseous Na(g) as a precursor to NaSO4 formation, the kinetics and mechanisms of the heterogeneous reaction H(g) + NaCl(s) yields Na(g) + HCl(g) was studied using atomic absorption spectroscopy combined with microwave discharge-vacuum flow reactor techniques at moderate temperatures. Preliminary results indicate the H-atom attack of solid NaCl vaporization is negligible; hence the corresponding gas phase (homogeneous) reaction no role in the observed Na(g) production.

Rosner, D. E.↗
NASA NTRS1979

Photochemistry of bromoacetylene - Formation of HBr and quenching of excited Br/4 2P 0 1/2/

The photolysis of bromacetylene is examined by means of vacuum ultraviolet flash photolysis-kinetic spectroscopy, with attention given to the production of Br atoms in the 2P 0 3/2 and 2P 0 1/2 states, the production of HBr, and UV absorption attributable to the ethynyl radical. Although Br(2P 0 1/2) and Br(2P 0 3/2) were both directly observed at the shortest delay time after the flash, strongly indicating the presence of the ethynyl radical, transient absorption by C2H was not detected in the range 125 to 180 nm. Quenching rate constants for the decay of the 2P 0 1/2 state of Br, which is observed to form concurrently with the ground state, are derived for quenching by He, CH2Br, CF4, and D2 from the pseudo-first-order decay rates. HBr was observed as a secondary photolysis product, and a model of its formation by the exothermic reaction of ground-state atoms with C2HBR, coupled with the secondary production of Br atoms, is found to agree well with the experiment.

Laufer, A. H.↗
NASA NTRS1988

Scanning Tunneling Microscopy methods for spectroscopic imaging of subsurface interfaces

A new method for spatially-resolved, spectroscopic investigation of subsurface interface structure has been developed. The method, Ballistic Electron Emission Microscopy (BEEM), is based on Scanning Tunneling Microscopy (STM) techniques. BEEM combines STM vacuum tunneling with unique ballistic electron spectroscopy capabilities. BEEM enables, for the first time, direct imaging of subsurface interface electronic properties with nanometer spatial resolution. STM topographic images of surface structure and BEEM images of subsurface properties are obtained simultaneously. BEEM capabilities are demonstrated by investigation of important metal-semiconductor interfaces.

Bell, L. D.↗