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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Disposal of hypergolic propellants, phase 6 task 4. Disposal pond products

Waste monomethyl hydrazine scrubber liquor, consisting of aqueous solutions containing small amounts of CH4, Cl2, CH3Cl, CH2Cl2, and CHCl3 as well as large amounts of CH3OH is scheduled to be dumped in stabilization ponds along with nitrate and nitrite salt solutions obtained as waste liquors from the N2O4 scrubbers. The wastes are investigated as to the hazardous materials generated by such combinations of items as described as well as the finite lifetime of such materials in the stabilization ponds. The gas liquid chromatograph was used in the investigation. A series of experiments designed to convert nitrate and nitrite salts to the environmentally innocuous N2O and N2 using solar energy is reported. Results indicate that this solar conversion is feasible.

Cohenour, B. C.↗
NASA NTRS1977

Atomic and molecular fluorescence as a stratospheric species monitor

The results of an investigation are presented evaluating the potential of atomic and molecular fluorescence as a stratospheric monitor of the concentrations of any one of 18 minor species: Cl, Cl2, ClO, ClO2, CO, H2, HCHO, HCl, HNO2, HNO3, H2S, NH3, NO, NO2, N2O, O, OH, and SO2. All spectral regions from the vacuum ultraviolet through the infrared were included. It was found that suitable systems can be constructed for the stratospheric monitoring of CO (5 ppb), NO2 (less than 1 ppb), OH (0.2 ppt), and O (50-200 ppt). The fluorescence sensitivities for Cl (0.5-1.0 ppt), H2 (0.2 ppm at 10 torr) and SO2 (1-10 ppb) are marginally insufficient with current technology.

Schofield, K.↗
NASA NTRS1977

Measurements of the electronic transition moment of the A 2 Pi-X 2 Pi system of ClO

The electronic transition moment of the A 2 Pi-X 2 Pi band system of ClO has been determined from spectral emission measurements behind incident shock waves in Cl2-O2 mixtures. The temperature of the radiating gas was typically 3500 K. Narrow bandpass radiometers were used to obtain absolute measurements of the ClO emission from which electronic transition moments were derived by a synthetic spectrum analysis. Absolute measurements of the O2 Schumann-Runge system and the photo-dissociation cross section of ClO are also reported.

Cooper, D. M.↗
NASA NTRS1977

Spontaneous emission from ScF in a supersonic mixing flame

An investigation was conducted of the two reactions: Sc + F2 yields ScF(asterisk) + F and Y + Cl2 yields YCl(asterisk) + Cl. Experiments were designed for studying the reactions under the relatively high pressure conditions (5-20 torr) appropriate for chemical laser operation. A shock tube was used to provide a short duration flow through a supersonic nozzle array. Shock wave heating is used to dissociate the ScCl3 or YCl3 at temperatures of about 6000 K, before the gases are accelerated and expanded through the supersonic nozzle array. The expanded primary flow is then mixed with a secondary flow of F2 introduced through slots at the trailing edge of each nozzle blade. Graphs show the temporal behavior of the visible spontaneous emission over the range from 3000 to 9000 A for a typical test condition, a microdensitometer tracing of the visible emission over the range from 4000 to 7000 A, and the spontaneous emission from ScF(asterisk) obtained by computer image processing of intensity data.

Fischell, D. R.↗
NASA NTRS1977

Rate constants for reactions of ClO/x/ of atmospheric interest

Chemical kinetics measurements on 82 gas phase reactions of chlorine containing species are reviewed. Recommended rate constants are given. The principal species of interest are Cl, Cl2, ClO, Cl2O, ClOO, OClO, CINO, HCl and halo derivatives of methane and ethane. Absorption spectra are given for 21 species. In addition the chemical kinetics methods used to obtain these data are discussed with regard to their applicability and reliability.

Watson, R. T.↗
NASA NTRS1978

The reaction of ClOO with NO

Reactions of ClOO with NO were studied by photolyzing Cl2 in the presence of NO and O2 with or without added N2. Steady-state photolysis results show that two reactions of ClOO and NO can occur, one forming ClO and the other forming ClNO. The rate constants for the reactions are calculated, and their values indicate that the reactions are probably not important in the stratosphere.

Wongdontri-Stuper, W.↗
NASA NTRS1980

Energy storage-boiler tank

Activities performed in an effort to demonstrate heat of fusion energy storage in containerized salts are reported. The properties and cycle life characteristics of a eutectic salt having a boiling point of about 385 C (NaCl, KCl, Mg Cl2) were determined. M-terphenyl was chosen as the heat transfer fluid. Compatibility studies were conducted and mild steel containers were selected. The design and fabrication of a 2MWh storage boiler tank are discussed.

Chubb, T. A.↗
NASA NTRS1979

Effect of interfacial species on shear strength of metal-sapphire contacts

The interfacial shear strength of the metal-insulator system has been studied by means of the coefficient of static friction of copper, nickel, or gold contacts on sapphire in ultrahigh vacuum. The effect on contact strength of adsorbed oxygen, nitrogen, chlorine, and carbon monoxide on the metal surfaces is reported. It was found that exposures as low as 1 L of O2 on Ni produced observable increases in contact strength, whereas exposures of 3 L of Cl2 lead to a decrease in contact strength. These results imply that submonolayer concentrations of these species at the interface of a thin Ni film on Al2O3 should affect film adhesion similarly. The atomic mechanism by which these surface or interface phases affect interfacial strength is not yet understood.

Pepper, S. V.↗
NASA NTRS1980

Spectra from nuclear-excited plasmas

The paper discusses the spectra taken from He-3(n,p)H-3 nuclear-induced plasmas under high thermal neutron flux, lasing conditions. Also, initial spectra are presented for U-235F6 generated plasmas. From an evaluation of these spectra, important atomic and molecular processes that occur in the plasma can be inferred. The spectra presented are the first to be generated by He-3 and U-235F6 nuclear reactions under high neutron flux, lasing conditions. The U-235(n,ff)FF reaction, which liberates 165 MeV of fission-fragment kinetic energy, creates plasmas that are of great interest, since at sufficiently high densities of U-235F6 the gas becomes self-critical; thus, there is no need for an external driving reactor (source of neutrons). The spectra from mixtures of He-3 and Ar, Xe, Kr, Ne, Cl2, F2 and N2 indicate little difference between high-pressure nuclear-induced plasmas and high-pressure electrically pulsed afterglow plasmas for noble-gas systems

De Young, R. J.↗
NASA NTRS1980

Asymmetrical ClO3 - Its possible formation from ClO and O2 and its possible reactions

An analysis of recent accurate experimental studies of Cl2-photosensitized O3 decomposition, in which O3 disappearance and OClO formation were directly monitored, suggests the possibility that the suppression of the quantum yield in the presence of O2 may be due to the formation of asymmetrical chlorine trioxide (ClO.O2). Other intermediaries, such as Cl2O2, which may also form in the system are not thought to explain the observations. In addition to its capacity to oxidize, which it shares with other peroxo compounds, asymmetrical ClO3 appears to undergo an interesting class of reactions in which the loosely bound O2 adduct is relatively easily displaced by reactive atoms and radicals such as chlorine.

Prasad, S. S.↗
NASA NTRS1981

Temperature dependence of the self-reaction of CH3O2 radicals

The rate constants for the reaction CH3O2 + CH3O2 yields products (1) were measured in the temperature range from 248 to 417 K, taking into consideration pressures in the range from 60 to 700 torr of N2. The experimental investigation was carried out in a Pyrex flash photolysis system employing ultraviolet absorption detection. Methylperoxy radicals (CH3O2) were produced by the photolysis of Cl2-CH4-O2 mixtures. Rate constants were measured by observing the second-order disappearance of CH3O2 radicals. Plots of 1/(CH3O2 optical density) vs. time were observed to be linear over a concentration change of a factor of 10-50. Results of the kinetic runs at each temperature are summarized in a table, and an Arrhenius plot of the data is shown in a graph.

Sander, S. P.↗
NASA NTRS1983

Cleaning chemistry of InSb(100) molecular beam epitaxy substrates

InSb has been used as a substrate for molecular beam epitaxy. For good epitaxial growth, a substrate surface which is smooth and clean on an atomic scale is required. Chemical cleaning procedures provide an oxide film to passivate the surface. This film is then desorbed by in situ heating. The material forming the film should, therefore, have a high vapor pressure at some temperature less than the substrate melting temperature. A chloride film appears to satisfy the latter requirement. The present investigation is, therefore, concerned with the formation of a chloride film rather than an oxide film. Carbon contamination has been found to cause problems in chemical cleaning procedures. The level of carbon contamination found in the case of chloride film formation, is therefore compared with the corresponding level observed in procedures using oxide films. It appears that a chloride film grown in connection with a short exposure time to a Cl2 plasma is preferable to other passivation films studied.

Vasquez, R. P.↗
NASA NTRS1984

Characterization of Open Circuit Voltage and Capacity as a Function of Time

It is noted from the data presented that Li/BCX cells lose approximately 8% of their rated capacity in the first 2 months of storage. After this period of time, little difference is noted in the average realized capacity; however, a significant increase in the range is observed. Over the same period of time the OCV falls at a rate of 0.02V per 1,000 hours. After a period of 8,000 hours the OCV appears stabilize at a value of approximately 3.75V. This may be related to changes in Cl2 concentration due to self-discharge or other reactions. These data indicate that no correlation exists between the reduced open circuit voltage and the realized capacity.

Krehl, P. W.↗
NASA NTRS1984

A measurement of the vibrational band strength for the v3 band of the HO2 radical

Laboratory measurements of the v(3) band strength of HO2 using a tunable diode laser to measure the absorption strength of a vibration-rotation line in the P branch near 1080/cm are reported. The HO2 is generated in a discharge-flow system by reaction of fluorine atoms with excess H2O2: F + H2O2 - HO2 + HF. The HO2 concentration is determined from measurements of F-atom concentrations using both chemical titration with Cl2 and tunable diode laser absorption by the F-atom spin-orbit transition near 404/cm. The experimental data are consistent with a value of k(3) = (1.6 + or - 0.3) x 10 to the 12th cu cm/s and a ratio k(4)/k(1) = 1.0 + or - 0.4. The line strength for the 6(15) - 7(16)F(1) transition is 2.9 x 10 to the -21 sq cm/molecule/cm, which corresponds to a v(3) band strength of 35 + or - 9/sq cm/(STP atm). This value is a factor of 1.6 to 6 lower than previous ab initio calculations.

Zahniser, M. S.↗
NASA NTRS1984

Reaction products on current or potential reversal in Li/SOCl2 cells

The products formed during abnormal operation due to current or potential reversal in Li/SOCl2 cells have been identified by several complementary analytical techniques. In addition to the expected corrosion of cell components, the following compounds were found: Cl2, SO2, SO2Cl2, S2Cl2 and SCl2. The presence of Cl2O and ClO2 reported by Salmon el al. (1982) has not been confirmed.

Carter, B. J.↗
NASA NTRS1985

Mechanistic studies related to the safety of Li/SOCl2 cells

Mechanistic studies of the reactions in Li-SOCl2 cells have been undertaken to improve understanding of the safety problems of these cells. The electrochemical reduction of 1.5M LiAlCl4/SOCl2 has been investigated using gas chromatography, electron spin resonance spectroscopy, and infrared spectroscopy. Cl2 and S2Cl2 have been identified as intermediates in the reduction of SOCl2, along with a radical species (g/xx/ = 2.004, g/yy/ = 2.016, g/zz/ = 2.008) and the proposed triplet ground-state dimer of this radical. SO2 and sulfur have been identified as products. Based upon these findings, a mechanism for the electrochemical reduction of 1.5M LiAlCl4/SOCl2 has been proposed, and its implications for safety of Li-SOCl2 cells during discharge to +0.5V at 25-30 C are discussed.

Carter, B. J.↗
NASA NTRS1985

Laboratory studies on the reactions between chlorine, sulfur dioxide, and oxygen - Implications for the Venus stratosphere

Fourier transform IR spectrophotometry is used to monitor the reactants and products in a Venus stratosphere simulation study involving the photolysis of mixtures of Cl2 and SO2, with and without O2 present in an atmosphere of N2. When several speculative reactions inferred from these experiments are incorporated by the Yung and DeMore (1982) model of Venus stratospheric chemistry, it emerges that SO2Cl2 is a key reservoir species for chlorine, and that the reaction between Cl and SO2 furnishes an important cycle for the destruction of O2 and the conversion of SO2 to H2SO4, thereby providing a possible solution to the photochemistry of the Venus stratosphere.

Demore, W. B.↗
NASA NTRS1985

An upper limit to the rate of the HCl + ClONO2 reaction

The reaction HCl + ClONO2 yields Cl2 + HNO3 has been studied by Fourier transform infrared spectroscopy and by a static wall-less UV absorption technique. An upper limit to the homogeneous bimolecular rate constant of 10 to the -19th cu cm/molecule per sec was established, making the reaction unimportant in the stratosphere.

Molina, L. T.↗