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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Rate constant for the fraction of atomic chlorine with formaldehyde from 200 to 500K

A flash photolysis - resonance fluorescence technique was used to measure rate constant. The results were independent of substantial variations in H2CO, total pressure (Ar), and flash intensity (i.e., initial Cl). The rate constant was shown to be invariant with temperature, the best representation for this temperature range being K = (7.48 + or - 0.50) x 10 to the minus 11 power cu cm molecule-1 s-1 where the error is one standard deviation. The rate constant is theoretically discussed and the potential importance of the reaction in stratospheric chemistry is considered.

Michael, J. V.↗
NASA NTRS1979

Lunar sample analysis

The surface composition of two samples from the highly shocked, glass-coated lunar basalt (12054) and from four glass-coated fragments from the 1-2 mm (14161) fines were examined by X-ray photoemission spectroscopy to determine whether the agglutination process itself is responsible for the difference between their surface and bulk compositions. Auger electron spectroscopy of glass balls from the 15425 and 74001 fines were analyzed to understand the nature, extent, and behavior of volatile phases associated with lunar volcanism. Initial results indicate that (1) volatiles, in the outer few atomic layers sampled, vary considerably from ball to ball; (2) variability over the surface of individual balls is smaller; (3) the dominant volatiles on the balls are S and Zn; and (4) other volatiles commonly observed are P, Cl, and K.

Housley, R. M.↗
NASA NTRS1978

A kinetics investigation of several reactions involving chlorine containing compounds

The technique of flash photolysis-resonance fluorescence was utilized to study nine reactions of stratospheric importance. The tropospheric degradation reactions of seven halogenated hydrocarbons were studied to assess their possible influx into the stratosphere. There are reactions of either Cl, OH, or O(3P) species with hydrogenated species, O3 or chlorinated compounds. Apart from the kinetic measurements, the quantum yield for the production of O(1D) from O3 in the crucial wavelength region of 293 to 316.5 nm was studied by utilizing a narrow wavelength laser as the photolysis source. The product formation was monitored by measuring the fluorescence of NO2 formed through O(1D) reaction with N2O followed by NO reaction with O3 to give NO2.

Davis, D. D.↗
NASA NTRS1979

Launch vehicle effluent measurements during the September 5, 1977, Titan 3 launch at Air Force eastern test range

Airborne effluent measurements and cloud physical behavior data are presented. The monitoring program included airborne effluent measurements in situ in the launch cloud, visible and infrared photography of cloud growth and physical behavior, and limited surface collection of rain samples. Effluent measurements included concentrations of HCl, Cl2, NO, nitric oxide, and particles as a function of time in the exhaust cloud. In situ particle mass concentration and number density were measured as a function of time and size in the range of 0.05 micron m to 30 micron m diameter. Measurement results were similar to those of previous launch monitorings. Maximum HCl and nitric oxide concentrations of Cl2 were maximum about 2 minutes after launch and by 10 to 15 minutes had decayed to less than 10 ppb (detection limit). Particle measurements showed most of the particles present to be below about 3-micron m diameter. Postlaunch analyses of collected particle samples showed significant amounts of Al (some cases Cl) from about 3-micron m to 0.04-micron m diameter.

Wornom, D. E.↗
NASA NTRS1978

Morphology and elemental composition analysis by size of rocket particulate effluent

Particulate samples collected on six stages of a quartz crystal microbalance cascade impactor mounted in an aircraft traversing the plume of a large solid-fueled rocket are analyzed, postflight, by scanning electron microscopy (SEM) and energy dispersed X-ray (EDXRA). The results indicate the morphology and elemental composition of the particles fall into several distinct groups. Those larger than about 0.5 micron in diameter and nearly spherical in shape contain, among elements with atomic numbers of 11 and higher, only aluminum, suggesting they are aluminum oxide formed in the solid rocket fuel combustion. Still larger but less symmetrical particles contain only sodium and chlorine. Particles much smaller than 0.5 micron seem to end up as agglomerates after impaction (or during the impaction process), and show a complex elemental make-up of Na, Al, S, Cl, K, Ca, Fe and Zn. The unagglomerated single particles smaller than 0.2 micron, on the other hand, show no evidence of elements above atomic number 11 at all, suggesting they may be carbon or hydrocarbon particles.

Chuan, R. L.↗
NASA NTRS1978

Fluorescent accessory phases in the carbonaceous matrix of ureilites

The carbonaceous matrix of ureilite meteorites (C-bearing olivine-pigeonite achondrites) contain abundant minute phases that emit a multicolored fluorescence under electron bombardment. These include NaCl and KCl, found in all seven ureilites studied, high-Si glass with pyroxene and chlorapatite quench crystals in North Haig, an unidentified high-Ca-Al-Cl phase in Novo Urei, and possibly free SiO2 in Novo Urei and Dingo Pup Donga. The origin of these phases is uncertain but some, especially chlorides and glass, may represent residual postcumulus materials precipitated from a late-stage interstitial liquid during the igneous phase of ureilite history.

Berkley, J. L.↗
NASA NTRS1978

Stratospheric trace gas sampling with chemical absorption filters

Recent interest in stratospheric chemistry, sparked in part by the suggested roles of atomic chlorine (Cl) and nitrogen oxides (NOx) in the catalytic destruction of ozone (O3), has made sampling and measurement of trace constituents above the tropopause highly desirable. An ongoing research program in the In Situ Studies Project at the National Center for Atmospheric Research carries out aircraft and balloon-borne stratospheric chemical sampling at regular intervals by using chemically impregnated filters to collect particles and reactive gases.

Bonelli, J. E.↗
NASA NTRS1979

Rate constant for the reaction of atomic chlorine with formaldehyde from 200 to 500 K

The absolute rate constant for the reaction of atomic chlorine with formaldehyde has been measured from 200 to 500 K using the flash photolysis-resonance fluorescence technique. The results were independent of substantial variations in (H2CO), total pressure (Ar), and flash intensity (i.e., initial (Cl)). The rate constant was shown to be invariant with temperature, the best representation for this temperature range being k-sub-1 = (7.48 + or - 0.50) times 10 to the -11 cu cm/molecule sec, where the error is one standard deviation. This result is compared with the only previous determination of k-sub-1, which was a relative value obtained at 298 K. The rate constant is theoretically discussed, and the potential importance of the reaction in stratospheric chemistry is considered.

Michael, J. V.↗
NASA NTRS1979

Primordial retention of carbon by the terrestrial planets

The thermodynamics of graphite, carbide, and carbonate formation in the presence of a solar-composition gas is examined, including the feasibility of producing solid solutions of carbon and carbides in metallic iron-nickel alloy. Gas-phase composition and graphite activities for a very wide range of nebular pressures and temperatures are calculated by a computer program that considers several hundred compounds, particularly all the important gaseous species containing H, C, O, N, S, Cl, P, and F. The results obtained indicate that CH4 and CO would be the dominant carbon compounds under all likely circumstances of temperature and pressure in the solar nebula, that graphite may have been the most abundant carbon species in certain cases, and that direct precipitation of graphite, carbides, or carbonates would have been impossible in the solar nebula. Carbon retention by the terrestrial planets is also investigated.

Lewis, J. S.↗
NASA NTRS1978

Isotopic fractionation of silicon in Allende inclusions

The variations of Si-30/Si-28 and Si-29/Si-28 in Allende inclusions are large, and are due predominantly to mass-dependent fractionation effects. Gas-soild or gas-liquid condensation processes at high temperatures have sufficiently large fractionation factors to account for the heavy-isotope enrichments in coarse-grained inclusions. Heavy isotope depletions are found in some Allende samples, and apparently result from a late-stage condensation. Thus, the silicon isotopic compositions may be useful for determining the sequence of events in forming the Allende meteorite. The peculiar Allende inclusion, Cl, has a very large mass-fractionated enrichment of Si-30/Si-28, and in addition, perhaps a small nuclear enrichment of Si-29. Olivine from the unusual pallasite, Eagle Station, has normal silicon isotope abundances even though it has a large O-16 excess.

Clayton, R. N.↗
NASA NTRS1979

The role of chemical engineering in space manufacturing

A survey of factors involved in space manufacturing is presented. It is shown that it will be more economical to obtain the necessary raw materials from the moon than from earth due to earth's greater gravity and atmosphere. Discussion covers what resources can be mined and recovered from the moon and what ranges of industrial feedstock can be provided from lunar materials, noting that metallurgy will be different in space due to the lack of key elements such as H, C, Na, Cl, etc. Also covered are chemical plant design, space environmental factors such as vacuum and zero gravity, recycling requirments, reagent and equipment mass, and unit operations such as materials handling and phase separation. It is concluded that a pilot plant in space could be an economic boon to mankind.

Waldron, R. D.↗
NASA NTRS1979

Volume-pumped nuclear lasers

A summary is given to experimental results on volume-pumped nuclear lasers obtained at the Langley Research Center. The first volume-pumped nuclear laser was achieved in 1976 using the He-3(n, p)H-3 reaction. Since that time laser output has increased by more than a factor of 1000 (from mW to W). Lasing has been demonstrated in He-3-Ar (1.27 and 1.79 micron), He-3-Xe (2.027, 3.5, and 3.65 microns), He-3-Kr (2.19 and 2.52 microns), and He-3-Cl (1.587 micron). Pressures of the lasing mixture range from 300 torr to 4 atm with a peak power output of 26 W were achieved in a He-3-Ar mixture with a multiple-pass laser configuration.

Hohl, F.↗
NASA NTRS1979

Star tracker error analysis: Roll-to-pitch nonorthogonality

An error analysis is described on an anomaly isolated in the star tracker software line of sight (LOS) rate test. The LOS rate cosine was found to be greater than one in certain cases which implied that either one or both of the star tracker measured end point unit vectors used to compute the LOS rate cosine had lengths greater than unity. The roll/pitch nonorthogonality matrix in the TNB CL module of the IMU software is examined as the source of error.

Corson, R. W.↗
NASA NTRS1975

Atomic emission spectroscopy

The relationship between the Slater-Condon theory and the conditions within the atom as revealed by experimental data was investigated. The first spectrum of Si, Rb, Cl, Br, I, Ne, Ar, and Xe-136 and the second spectrum of As, Cu, and P were determined. Methods for assessing the phase stability of fringe counting interferometers and the design of an autoranging scanning system for digitizing the output of an infrared spectrometer and recording it on magnetic tape are described.

Andrew, K. H.↗
NASA NTRS1980

Atmospheric bromine and ozone perturbations in the lower stratosphere

The role of bromine compounds in the photochemistry of the natural and perturbed stratosphere has been reexamined using an expanded reaction scheme and the results of recent laboratory studies of several key reactions. The most important finding is that through the reaction BrO + ClO yielding Br + Cl + O2 there is a synergistic effect between bromine and chlorine which results in an efficient catalytic destruction of ozone in the lower stratosphere. One-dimensional photochemical model results indicate that BrO is the major bromine species throughout the stratosphere, followed by BrONO2, HBr, HOBr and Br. It is shown from the foregoing that bromine is more efficient than chlorine as a catalyst for destroying ozone, and the implications for stratospheric ozone of possible future growth in the industrial and agricultural use of bromine are discussed. Bromine concentrations of 20 pptv (2 x 10 to the -11th power), as suggested by recent observations, can decrease the present-day integrated ozone column density by 2.4%, and can enhance ozone depletion from steady-state chlorofluoromethane release at 1973 rates by a factor of 1.1-1.2.

Yung, Y. L.↗
NASA NTRS1979

Is the Martian lithosphere sulfur rich

Several models are proposed to explain the abundance of sulfurand chlorine-containing compounds in the Martian fines. Preliminary analyses attributed the S and Cl enrichment to the upward migration of soluble salt. Alternative possibilities are examined, including remnant primitive lithosphere, a primitive component in the regolith, and trapping of volcanic gases. The alternative models encompass various features of the accretion chemistry thermal history, and core size-mass relationships that have been proposed for Mars.

Clark, B. C.↗
NASA NTRS1980

Product distribution for the reaction of HO2 with ClO

The paper reports the direct measurement of the reaction product HOCl from the reaction of H2O with ClO, and sets an upper limit for the possible product O3, using a discharge flow/mass spectrometry/resonance fluorescence apparatus. The upper limits of the reaction channel producing HCl + O3 are 1.5% at 298 K and 3.0% at 248 K. It is seen that the HCl production rate from the HO2 + ClO reaction could be as large as that from the Cl + CH4 reaction in the lower and middle stratosphere. Thus, this reaction may possibly increase the HCl production rate appreciably and thereby reduce the calculated O3 destruction by chlorofluoromethanes.

Leu, M.-T.↗
NASA NTRS1980

Kinetics study of the Cl/2P/ + Cl2O yields Cl2 + ClO reaction at 298 K

The kinetics of the Cl + Cl2O reaction, a possible source of ClO(2 Pi) radicals for atmospheric photochemical studies, are investigated at 298 K. The discharge flow/mass spectrometry and discharge flow/resonance fluorescence techniques were used to monitor the decay of C12O in the presence of excess concentrations of atomic chlorine and chlorine monoxide, respectively. The pseudo-first order rate constants obtained from both experiments are found to be in excellent agreement, averaging 9.8 + or - 0.8 x 10 to the -11th cu cm/molecule per sec. Results are consistent with the lower limit obtained by Edgecombe et al. (1957) but differ by a factor of 150 from those of Basco and Dogra (1971). The present value is also noted to be consistent with a lower value for the rate constant of the reaction of oxygen atoms with Cl2O.

Ray, G. W.↗