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Sample records for atmospheric reaction products

  1. Studies of the Atmospheric Chemsitry of Energy-Related Volatile Organic Compounds and of their Atmospheric Reaction Products

    SciTech Connect

    Roger Atkinson; Janet Arey

    2007-04-14

    The focus of this contract was to investigate selected aspects of the atmospheric chemistry of volatile organic compounds (VOCs) emitted into the atmosphere from energy-related sources as well as from biogenic sources. The classes of VOCs studied were polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs, the biogenic VOCs isoprene, 2-methyl-3-buten-2-ol and cis-3-hexen-1-ol, alkenes (including alkenes emitted from vegetation) and their oxygenated atmospheric reaction products, and a series of oxygenated carbonyl and hydroxycarbonyl compounds formed as atmospheric reaction products of aromatic hydrocarbons and other VOCs. Large volume reaction chambers were used to investigate the kinetics and/or products of photolysis and of the gas-phase reactions of these organic compounds with hydroxyl (OH) radicals, nitrate (NO3) radicals, and ozone (O3), using an array of analytical instrumentation to analyze the reactants and products (including gas chromatography, in situ Fourier transform infrared spectroscopy, and direct air sampling atmospheric pressure ionization tandem mass spectrometry). The following studies were carried out. The photolysis rates of 1- and 2-nitronaphthalene and of eleven isomeric methylnitronaphthalenes were measured indoors using blacklamp irradiation and outdoors using natural sunlight. Rate constants were measured for the gas-phase reactions of OH radicals, Cl atoms and NO3 radicals with naphthalene, 1- and 2-methylnaphthalene, 1- and 2-ethylnaphthalene and the ten dimethylnaphthalene isomers. Rate constants were measured for the gas-phase reactions of OH radicals with four unsaturated carbonyls and with a series of hydroxyaldehydes formed as atmospheric reaction products of other VOCs, and for the gas-phase reactions of O3 with a series of cycloalkenes. Products of the gas-phase reactions of OH radicals and O3 with a series of biogenically emitted VOCs were identified and quantified. Ambient atmospheric measurements of the concentrations of a

  2. Kinetic and Product Yields of the Gas-Phase Reactions of Isoprene Hydroperoxides with Atmospheric Oxidants

    NASA Astrophysics Data System (ADS)

    Kumar, V.; Lozano, E. I.; Maitra, S.; Manning, D. M.; Cervantes, R.; Hasson, A. S.

    2015-12-01

    Isoprene is a volatile organic compound (VOC) that is emitted into the atmosphere by plants and trees. It has the largest emission rate of any non-methane VOC and is very reactive, and therefore has a major impact on the chemical composition of the atmosphere. Isoprene Hydroperoxides (IHP) are formed in the atmosphere from the chemical degradation of isoprene. These compounds can then potentially react in the atmosphere with atmospheric oxidants (ozone, OH, NO3) to produce secondary products. This chemistry is potentially important as it may contribute to particle growth and to mediation of ozone concentrations. In this work, the kinetics and mechanisms of the reactions of two IHPs with ozone were investigated. IHPs were synthesized and purified, and were characterized by NMR and HPLC. The gas phase chemistry of these compounds was then studied in chamber experiments using PTRMS as the primary analytical tool. The rate coefficients for reaction with ozone were measured at room temperature and 1 atmosphere using the relative rate technique, and yields of major gas phase reaction products were measured. Implications of these results will be discussed.

  3. Pressure Effects on Product Channels of Hydrocarbon Radical-Radical Reactions; Implications for Modelling of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Fahr, A.; Halpern, J.; N'doumi, M.

    2011-10-01

    Previously we had studied the kinetics and product channels of small unsaturated hydrocarbon radical (C2 and C3s) reactions relevant to planetary atmospheric modelling. Reactions of C2 radicals (such as vinyl, H2CCH and ethynyl C2H) and C3 radicals (such as propargyl, HCCCH2 and allyl, H2CCCH3) can affect the abundances of a large number of stable observable C3, C4, C5, C6 and larger molecules, including linear, aromatic and even poly aromatic molecules. We have experimentally determined pressuredependent product yields for self- and cross-radical reactions performed at 298 K and at selected pressures between ~4 Torr (0.5 kPa) and 760 Torr (101 kPa). Final products were determined by gas chromatograph with mass spectrometry/flame ionization detection (GC/MS/FID). In some cases complementary computational studies extended the pressure and temperature range of the observations and provided valuable information on complex reaction mechanisms. These studies provide a systematic framework so that important energetic and structural parameters for radical-radical reactions can be assessed. Here we report a compilation of our earlier results relevant to planetary atmospheres in addition to recent ones for allyl radical (H2CCCH3) reactions.

  4. Ozonolysis of methyl oleate monolayers at the air-water interface: oxidation kinetics, reaction products and atmospheric implications.

    PubMed

    Pfrang, Christian; Sebastiani, Federica; Lucas, Claire O M; King, Martin D; Hoare, Ioan D; Chang, Debby; Campbell, Richard A

    2014-07-14

    Ozonolysis of methyl oleate monolayers at the air-water interface results in surprisingly rapid loss of material through cleavage of the C=C bond and evaporation/dissolution of reaction products. We determine using neutron reflectometry a rate coefficient of (5.7 ± 0.9) × 10(-10) cm(2) molecule(-1) s(-1) and an uptake coefficient of ∼3 × 10(-5) for the oxidation of a methyl ester monolayer: the atmospheric lifetime is ∼10 min. We obtained direct experimental evidence that <2% of organic material remains at the surface on atmospheric timescales. Therefore known long atmospheric residence times of unsaturated fatty acids suggest that these molecules cannot be present at the interface throughout their ageing cycle, i.e. the reported atmospheric longevity is likely to be attributed to presence in the bulk and viscosity-limited reactive loss. Possible reaction products were characterized by ellipsometry and uncertainties in the atmospheric fate of organic surfactants such as oleic acid and its methyl ester are discussed. Our results suggest that a minor change to the structure of the molecule (fatty acid vs. its methyl ester) considerably impacts on reactivity and fate of the organic film. PMID:24870051

  5. Reaction products and mechanisms for the reaction of n-butyl vinyl ether with the oxidants OH and Cl: Atmospheric implications

    NASA Astrophysics Data System (ADS)

    Colmenar, Inmaculada; Martín, Pilar; Cabañas, Beatriz; Salgado, Sagrario; Tapia, Araceli; Martínez, Ernesto

    2015-12-01

    A reaction product study for the degradation of butyl vinyl ether (CH3(CH2)3OCHdbnd CH2) by reaction with chlorine atoms (Cl) and hydroxyl radicals (OH) has been carried out using Fourier Transform Infrared absorption spectroscopy (FTIR) and/or Gas Chromatography-Mass Spectrometry with a Time of Flight analyzer (GC-TOFMS). The rate coefficient for the reaction of butyl vinyl ether (BVE) with chlorine atoms has also been evaluated for the first time at room temperature (298 ± 2) K and atmospheric pressure (708 ± 8) Torr. The rate coefficient obtained was (9.9 ± 1.5) × 10-10 cm3 molecule-1 s-1 and this indicates the high reactivity of butyl vinyl ether with Cl atoms. However, this value may be affected by the dark reaction of BVE with Cl2. The results of a qualitative study of the Cl reaction show that the main oxidation products are butyl formate (CH3(CH2)3OC(O)H), butyl chloroacetate (CH3(CH2)3OC(O)CH2Cl and formyl chloride (HCOCl). Individual yields in the ranges ∼16-40% and 30-70% in the absence and presence of NOx, respectively, have been estimated for these products. In the OH reaction, butyl formate and formic acid were identified as the main products, with yields of around 50 and 20%, respectively. Based on the results of this work and a literature survey, the addition of OH radicals and Cl atoms at the terminal C atom of the double bond in CH3(CH2)3OCHdbnd CH2 has been proposed as the first step in the reaction mechanism for both of the studied oxidants. The tropospheric lifetime of butyl vinyl ether is very short and, as a consequence, it will be rapidly degraded and will only be involved in tropospheric chemistry at a local level. The degradation products of these reactions should be considered when evaluating the atmospheric impact.

  6. The molecular dynamics of atmospheric reaction

    NASA Technical Reports Server (NTRS)

    Polanyi, J. C.

    1971-01-01

    Detailed information about the chemistry of the upper atmosphere took the form of quantitative data concerning the rate of reaction into specified states of product vibration, rotation and translation for exothermic reaction, as well as concerning the rate of reaction from specified states of reagent vibration, rotation and translation for endothermic reaction. The techniques used were variants on the infrared chemiluminescence method. Emphasis was placed on reactions that formed, and that removed, vibrationally-excited hydroxyl radicals. Fundamental studies were also performed on exothermic reactions involving hydrogen halides.

  7. Quantifying VOC-Reaction Tracers, Ozone Production, and Continuing Aerosol Production Rates in Urban and Far-Downwind Atmospheres

    NASA Technical Reports Server (NTRS)

    Chatfield, Robert; Ren, X.; Brune, W.; Fried, A.; Schwab, J.

    2008-01-01

    reaction products) and aerosol production, looking for VOC's that might be most implicated. All three variables j(sub rads), [HCHO], and [NO] are relatively easily measured in widespread air pollution monitoring networks, and all are deducible form space-borne observations, though estimation of [NO] from [NO2] (the species observable from space) may require care. We report also on airborne and surface observations of HCHO, suggesting that concentrated (urban) and more diffuse (forest) sources may be distinguishable from space. The use of the 3.58 micron microwindow for HCHO remote sensing should allow much sharper resolution of HCHO than the UV. UV sensing requires large and expensive instruments, but even these seem justified since formaldehyde is so informative.

  8. Acidic reaction products of mono- and sesquiterpenes in atmospheric fine particles in a boreal forest

    NASA Astrophysics Data System (ADS)

    Vestenius, M.; Hellén, H.; Levula, J.; Kuronen, P.; Helminen, K. J.; Nieminen, T.; Kulmala, M.; Hakola, H.

    2014-01-01

    Biogenic acids were measured from PM2.5 aerosols at SMEAR II station (Station For Measuring Forest Ecosystem-Atmosphere Relations) in Finland from June 2010 until October 2011. The measured organic acids were pinic, pinonic, caric, limonic and caryophyllinic acids from oxidation of α-pinene, β-pinene, limonene, Δ3-carene and β-caryophyllene. Due to lack of authentic standards caric, limonic and caryophyllinic acids were synthesized at the Laboratory of Organic Chemistry, University of Helsinki. The highest terpenoic acid concentrations were measured during summer concomitant with the precursor mono- and sesquiterpenes. Of the acids β-caryophyllinic acid had highest concentrations in summer, but during other times of the year pinonic acid was the most abundant. The β-caryophyllinic acid contribution was higher than expected on the basis of emission calculations of precursor compounds and yields in oxidation experiments in smog chambers implicating that β-caryophyllene emissions or β-caryophyllinic acid yields are underestimated. Concentration ratios between terpenoic acids and their precursor were clearly lower in summer than in winter indicating stronger partitioning to the aerosol phase during cold winter season. The β-caryophyllinic and caric acids were correlated with the accumulation mode particle number concentrations.

  9. Acidic reaction products of monoterpenes and sesquiterpenes in atmospheric fine particles in a boreal forest

    NASA Astrophysics Data System (ADS)

    Vestenius, M.; Hellén, H.; Levula, J.; Kuronen, P.; Helminen, K. J.; Nieminen, T.; Kulmala, M.; Hakola, H.

    2014-08-01

    Biogenic acids were measured in aerosols at the SMEAR II (Station for Measuring Forest Ecosystem-Atmosphere Relations II) station in Finland from June 2010 until October 2011. The analysed organic acids were pinic, pinonic, caric, limonic and caryophyllinic acids from oxidation of α-pinene, β-pinene, limonene, Δ3-carene and β-caryophyllene, respectively. Due to a lack of authentic standards, the caric, limonic and caryophyllinic acids were synthesised for this study. The mean, median, maximum and minimum concentrations (ng m-3) were as follows: limonic acid (1.26, 0.80, 16.5, below detection limit (< LOD)), pinic acid (5.53, 3.25, 31.4, 0.15), pinonic acid (9.87, 5.07, 80.1, < LOD), caric acid (5.52, 3.58, 49.8, < LOD), and caryophyllinic acid (7.87, 6.07, 86.1, < LOD). The highest terpenoic acid concentrations were measured during the summer. Of the acids, β-caryophyllinic acid showed the highest concentrations in summer, but during other times of the year pinonic acid was the most abundant. The β-caryophyllinic acid contribution was higher than expected, based on the emission calculations of the precursor compounds and yields from oxidation experiments in smog chambers, implying that the β-caryophyllene emissions or β-caryophyllinic acid yields were underestimated. The concentration ratios between terpenoic acids and their precursors were clearly lower in summer than in winter, indicating stronger partitioning to the aerosol phase during the cold winter season. The β-caryophyllinic and caric acids were weakly correlated with the accumulation-mode particle number concentrations.

  10. The oleic acid-ozone heterogeneous reaction system: products, kinetics, secondary chemistry, and atmospheric implications of a model system a review

    NASA Astrophysics Data System (ADS)

    Zahardis, J.; Petrucci, G. A.

    2006-11-01

    The heterogeneous processing of organic aerosols by trace oxidants has many implications to atmospheric chemistry and climate regulation. This review covers a model heterogeneous reaction system (HRS): the oleic acid-ozone HRS and other reaction systems featuring fatty acids, and their derivatives. The analysis of the primary products of ozonolysis (azelaic acid, nonanoic acid, 9-oxononanoic acid, nonanal) is described. Anomalies in the relative product yields are noted and explained by the observation of secondary chemical reactions. The secondary reaction products arising from reactive Criegee intermediates are mainly peroxidic, notably secondary ozonides and α-acyloxyalkyl hydroperoxide polymers. These highly oxygenated products are of low volatility and hydrophilic which may enhance the ability of particles to act as cloud condensation nuclei. The kinetic description of this HRS is critically reviewed. Most kinetic studies suggest this oxidative processing is either a near surface reaction that is limited by the diffusion of ozone or a surface based reaction. Internally mixed particles and coatings represent the next stage in the progression towards more realistic proxies of tropospheric organic aerosols and a description of the products and the kinetics resulting from the ozonolysis of these proxies, which are based on fatty acids or their derivatives, is presented. Finally, a series of atmospheric implications of oxidative processing of particulate containing fatty acids is presented. These implications include the extended lifetime of unsaturated species in the troposphere facilitated by the presence of solids, semisolids or viscous phases, and an enhanced rate of ozone uptake by particulate unsaturates compared to corresponding gas phase organics. Ozonolysis of oleic acid enhances its CCN activity, which implies that oxidatively processed particulate may contribute to indirect forcing of radiation. Other effects, including the potential role of aldehydic

  11. Atmospheric Chemistry Data Products

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This presentation poster covers data products from the Distributed Active Archive Center (DAAC) of the Goddard Earth Sciences (GES) Data and Information Services Center (DISC). Total Ozone Mapping Spectrometer products (TOMS) introduced in the presentation include TOMS Version 8 as well as Aura, which provides 25 years of TOMS and Upper Atmosphere Research Satellite (UARS) data. The presentation lists a number of atmospheric chemistry and dynamics data sets at DAAC.

  12. The oleic acid-ozone heterogeneous reaction system: products, kinetics, secondary chemistry, and atmospheric implications of a model system - a review

    NASA Astrophysics Data System (ADS)

    Zahardis, J.; Petrucci, G. A.

    2007-02-01

    The heterogeneous processing of organic aerosols by trace oxidants has many implications to atmospheric chemistry and climate regulation. This review covers a model heterogeneous reaction system (HRS): the oleic acid-ozone HRS and other reaction systems featuring fatty acids, and their derivatives. The analysis of the commonly observed aldehyde and organic acid products of ozonolysis (azelaic acid, nonanoic acid, 9-oxononanoic acid, nonanal) is described. The relative product yields are noted and explained by the observation of secondary chemical reactions. The secondary reaction products arising from reactive Criegee intermediates are mainly peroxidic, notably secondary ozonides and α-acyloxyalkyl hydroperoxide oligomers and polymers, and their formation is in accord with solution and liquid-phase ozonolysis. These highly oxygenated products are of low volatility and hydrophilic which may enhance the ability of particles to act as cloud condensation nuclei (CCN). The kinetic description of this HRS is critically reviewed. Most kinetic studies suggest this oxidative processing is either a near surface reaction that is limited by the diffusion of ozone or a surface based reaction. Internally mixed particles and coatings represent the next stage in the progression towards more realistic proxies of tropospheric organic aerosols and a description of the products and the kinetics resulting from the ozonolysis of these proxies, which are based on fatty acids or their derivatives, is presented. Finally, the main atmospheric implications of oxidative processing of particulate containing fatty acids are presented. These implications include the extended lifetime of unsaturated species in the troposphere facilitated by the presence of solids, semi-solids or viscous phases, and an enhanced rate of ozone uptake by particulate unsaturates compared to corresponding gas-phase organics. Ozonolysis of oleic acid enhances its CCN activity, which implies that oxidatively processed

  13. Reactions of OH with. alpha. -pinene and. beta. -pinene in air: Estimate of global CO production from the atmosphere oxidation of terpenes

    SciTech Connect

    Hatakeyama, Shiro; Izumi, Katsuyuki; Fukuyama, Tsutomu; Akimoto, Hajime; Washida, Nobuaki )

    1991-01-20

    Reactions of OH with {alpha}-pinene and {beta}-pinene were studied for the purpose of obtaining the basic data to estimate the emission rate of CO from the photooxidation of terpenes in the atmosphere. In the presence of NO the main product was pinonaldehyde and 6,6-dimethylbicyclo(3.1.1)heptan-2-one from {alpha}- and {beta}-pinene, respectively, and the yield was 56{plus minus}4 and 79{plus minus}8%, respectively. In the absence of NO the yield was remarkably lower, and the yield of organic aerosols was enhanced. For {alpha}-pinene 56 {plus minus} 3% was obtained as a yield of aerosols on the carbon number basis. Gross annual emission of CO from the reactions of OH with terpenes was estimated to be 22 Tg C/yr (50 Tg CO/yr) by regarding {alpha}-pinene as the representative of terpenes, on the basis of the annual emission rate of terpenes, estimated lifetime of pinenes in the atmosphere, the apparent rate constant for the intermediate to form CO, and the estimated yield of CO from the secondary oxidation of pinonaldehyde. The ultimate yield of CO from the tropospheric oxidation of terpenes (including both ozone and OH reactions) was estimated to be 20% on the carbon number basis, and the total annual emission of CO was evaluated to be 96 Tg C/yr (222 Tg CO/yr).

  14. Kinetic and products study of the gas-phase reaction of Lewisite with ozone under atmospheric conditions.

    PubMed

    Wang, Haitao; Zhang, Yuanpeng; Guo, Xiaodi; Shao, Yusheng; Gao, Runli; Liang, Dejian; Sun, Hao

    2016-02-01

    The rate constant for the gas-phase reaction of O3 and Lewisite was studied in air using the smog chamber technique. The experiments were carried out under pseudo-first-order reaction conditions with [O3]≪[Lewisite]. The observed rate constant of O3 with Lewisite was (7.83 ± 0.38) × 10(-19)cm(3)/(molecule·sec) at 298 ± 2K. Lewisite was discussed in terms of reactivity with O3 and its relationship with the ionization potential. Our results show that the rate constant for the gas-phase reaction of O3 with Lewisite is in line with the trend of the rate constants of O3 with haloalkenes. PMID:26969539

  15. REACTIONS OF OXY RADICALS IN THE ATMOSPHERE

    EPA Science Inventory

    Results are presented of a research program concerned with the study of selected reactions of importance in atmospheric chemistry. The decomposition of peroxyacetyl nitrate (PAN) was studied over the temperature range 25-39C. The rate constant was determined to be log k = 16.29 -...

  16. Kinetics investigations of atmospheric chemical reactions

    SciTech Connect

    Hills, A.J.

    1987-01-01

    Two separate gas-phase kinetics investigations were performed using a low-pressure fast-flow system with mass spectrometer detection. The first part of this research was a study of the atmospheric reactivity of diatomic sulfur, S/sub 2/. Rates of the reactions of sulfur with O, O/sub 2/, O/sub 3/, N/sub 2/O, NO, and NO/sub 2/ were investigated at 409 K and low pressure (0.89-3.0 Torr) in a discharge-flow system with mass spectrometric detection. The second investigation involves a study of the synergistic coupling of atmospheric bromine and chlorine chemistry. Recent measurements of ozone in the stratosphere over Antarctica have shown that the springtime ozone column decreased by 40% from 1960 to 1985. Both dynamical and chemical theories have been advanced to explain the formation of the Antarctic ozone hole. Prominent among these theories is that a synergistic interaction between gas-phase BrO and ClO radicals may be responsible for springtime ozone loss. The overall rate constant for the reaction, BrO + ClO ..-->.. Br + OClO ..-->.. Br + Cl + O/sub 2/ ..-->.. BrCl + O/sub 2/, has been measured over the temperature range 241-408 K. The rate constant for the overall reaction equals (8.2 +/- 1.0) 10/sup -12/ cm/sup 3//molecule s, independent of temperature.

  17. Atmospheric chemistry: Laboratory studies of kinetics of important reactions

    NASA Astrophysics Data System (ADS)

    Smith, S. J.

    Experiments to measure the rate constants for some reactions of the atmospherically important nitrate radical (NO3) are described using the discharge-flow technique. The nitrate radical was monitored by optical absorption at lambda = 662 nm. The reactions of NO3 with some stable organic and inorganic substrates are reported. The temperature dependences of some of the rate constants were also determined (298 less than T less than 523 K). In most cases, computer simulation was used to extract the rate constant for the primary process because the time-dependent behavior of (NO3) was affected by secondary reactions of NO3 with products of the primary interaction. The Arrhenius parameter for the reactions of NO3 with CH3CH3, CH2CH2, CH3OH, CHCl3, and HCl were determined. The activation energies for the reactions studied between NO3 and some alkynes are presented along with the corresponding pre-exponential factors. Some reactions were studied at room temperature (298 plus or minus 2 K) only and the rate constants found (in units of cubic cm/molecule sec) are: buta-1,3-diene (1.8 x 10 (exp -13), isobutene (2.8 x 10 (exp -13), HBr (1.3 x 10 (exp -15) and hex-2-yne (3.0 x 10 (exp -14). Non-Arrhenius behavior was found in the reactions of NO3 with n-butane, isobutane and propene. The empirical variation of these rate constants with temperature is presented. The curvature of the Arrhenius plots is discussed in terms of (1) a temperature-dependent pre-exponential factor, and (2) the possibility that two competing channels, possessing differing activation energies, exist for each reaction. The atmospheric implications of these reactions are discussed with reference to the nighttime production of nitric acid and the importance of the these reactions as loss processes for NO3.

  18. Evidence for heterogeneous reactions in the atmosphere

    NASA Astrophysics Data System (ADS)

    Hidy, George M.

    Verification of heterogeneous reactions in the atmosphere through observations has remained a difficult, perhaps unachievable task because of the diversity and complexity of simultaneous chemical interactions which are suspected to occur. However, recent measurements combined with data analysis show promise for supplying both direct and indirect evidence of heterogeneous sulfur oxide and nitrogen oxide chemistry. Examples of useful methods are provided, which include (1) direct interpretation of observations in and near clouds and inference from thermodynamic properties, (2) inspection of combinations of aerometric data, (3) inference from statistical analysis, (4) comparison of observations with a validated air quality model, and (5) differences in particle size/composition distributions. An example involving thermodynamics is dry ammonium nitrate undergoing equilibrium transformation to the vapor phase, which is very sensitive to temperature. The other sample results presented suggest that heterogeneous oxidation of SO2 to sulfate may occur in the presence of suspended liquid water, particularly in winter, either through media buffered by absorbed ammonia or via suspended soot in droplets. No observational evidence has been found supporting metal-oxide- or ion-catalyzed reactions of sulfur dioxide or nitrogen oxides under atmospheric conditions.

  19. Reaction product imaging

    SciTech Connect

    Chandler, D.W.

    1993-12-01

    Over the past few years the author has investigated the photochemistry of small molecules using the photofragment imaging technique. Bond energies, spectroscopy of radicals, dissociation dynamics and branching ratios are examples of information obtained by this technique. Along with extending the technique to the study of bimolecular reactions, efforts to make the technique as quantitative as possible have been the focus of the research effort. To this end, the author has measured the bond energy of the C-H bond in acetylene, branching ratios in the dissociation of HI, the energetics of CH{sub 3}Br, CD{sub 3}Br, C{sub 2}H{sub 5}Br and C{sub 2}H{sub 5}OBr dissociation, and the alignment of the CD{sub 3} fragment from CD{sub 3}I photolysis. In an effort to extend the technique to bimolecular reactions the author has studied the reaction of H with HI and the isotopic exchange reaction between H and D{sub 2}.

  20. Investigation of the atmospheric reactions of chloropicrin

    NASA Astrophysics Data System (ADS)

    Carter, William P. L.; Luo, Dongmin; Malkina, Irina L.

    An experimental and modeling study was conducted to assess the atmospheric impacts of chloropicrin emissions. Chloropicrin absorption cross sections were measured in the ˜ 270-390 nm wavelength region, and its overall photodecomposition quantum yield under simulated sunlight conditions was found to be 0.87 ± 0.26. In environmental chamber experiments, chloropicrin significantly enhanced rates of NO oxidation, O 3 formation, and consumptions of alkanes and other organic reactants. This is attributed to the formation of Cl atoms and NO x in its photodecomposition. A previously developed atmospheric chemical mechanism was expanded to include chloropicrin and Cl atom reactions. It gave reasonably good simulations of the chamber experiments. This mechanism predicted that when emitted into polluted urban atmospheres, chloropicrin would have between 0.4 and 1.5 times the ozone impact of the average of emitted VOCs on a mass emitted basis. This value varied depending on environmental conditions and assumptions made concerning the photodecomposition mechanism. The data obtained in this study were inconsistent with a previous study of chloropicrin's photodecomposition in air, probably due to differences in the light sources employed.

  1. Crossed molecular beam studies of atmospheric chemical reaction dynamics

    SciTech Connect

    Zhang, Jingsong

    1993-04-01

    The dynamics of several elementary chemical reactions that are important in atmospheric chemistry are investigated. The reactive scattering of ground state chlorine or bromine atoms with ozone molecules and ground state chlorine atoms with nitrogen dioxide molecules is studied using a crossed molecular beams apparatus with a rotatable mass spectrometer detector. The Cl + O{sub 3} {yields} ClO + O{sub 2} reaction has been studied at four collision energies ranging from 6 kcal/mole to 32 kcal/mole. The derived product center-of-mass angular and translational energy distributions show that the reaction has a direct reaction mechanism and that there is a strong repulsion on the exit channel. The ClO product is sideways and forward scattered with respect to the Cl atom, and the translational energy release is large. The Cl atom is most likely to attack the terminal oxygen atom of the ozone molecule. The Br + O{sub 3} {yields} ClO + O{sub 2} reaction has been studied at five collision energies ranging from 5 kcal/mole to 26 kcal/mole. The derived product center-of-mass angular and translational energy distributions are quite similar to those in the Cl + O{sub 3} reaction. The Br + O{sub 3} reaction has a direct reaction mechanism similar to that of the Cl + O{sub 3} reaction. The electronic structure of the ozone molecule seems to play the central role in determining the reaction mechanism in atomic radical reactions with the ozone molecule. The Cl + NO{sub 2} {yields} ClO + NO reaction has been studied at three collision energies ranging from 10.6 kcal/mole to 22.4 kcal/mole. The center-of-mass angular distribution has some forward-backward symmetry, and the product translational energy release is quite large. The reaction proceeds through a short-lived complex whose lifetime is less than one rotational period. The experimental results seem to show that the Cl atom mainly attacks the oxygen atom instead of the nitrogen atom of the NO{sub 2} molecule.

  2. Heterogeneous atmospheric reactions - Sulfuric acid aerosols as tropospheric sinks

    NASA Technical Reports Server (NTRS)

    Baldwin, A. C.; Golden, D. M.

    1979-01-01

    The reaction probabilities of various atmospheric species incident on a bulk sulfuric acid surface are measured in order to determine the role of sulfuric acid aerosols as pollutant sinks. Reaction products and unreacted starting materials leaving a Knudsen cell flow reactor after collision at 300 K with a H2SO4 surface or a soot surface were detected by mass spectrometry. Significant collision reaction probabilities are observed on a H2SO4 surface for H2O2, HNO3, HO2NO2, ClONO2, N2O5, H2O and NH3, and on soot for NH3. Estimates of the contribution of heterogeneous reactions to pollutant removal under atmospheric conditions indicate that while aerosol removal in the stratosphere is insignificant (loss rate constants approximately 10 to the -10th/sec), heterogeneous reactions may be the dominant loss process for several tropospheric species (loss rate constant approximately 10 to the -5th/sec, comparable to photolysis rate constants).

  3. Atmospheric science and power production

    SciTech Connect

    Randerson, D.

    1984-07-01

    This is the third in a series of scientific publications sponsored by the US Atomic Energy Commission and the two later organizations, the US Energy Research and Development Adminstration, and the US Department of Energy. The first book, Meteorology and Atomic Energy, was published in 1955; the second, in 1968. The present volume is designed to update and to expand upon many of the important concepts presented previously. However, the present edition draws heavily on recent contributions made by atmospheric science to the analysis of air quality and on results originating from research conducted and completed in the 1970s. Special emphasis is placed on how atmospheric science can contribute to solving problems relating to the fate of combustion products released into the atmosphere. The framework of this book is built around the concept of air-quality modeling. Fundamentals are addressed first to equip the reader with basic background information and to focus on available meteorological instrumentation and to emphasize the importance of data management procedures. Atmospheric physics and field experiments are described in detail to provide an overview of atmospheric boundary layer processes, of how air flows around obstacles, and of the mechanism of plume rise. Atmospheric chemistry and removal processes are also detailed to provide fundamental knowledge on how gases and particulate matter can be transformed while in the atmosphere and how they can be removed from the atmosphere. The book closes with a review of how air-quality models are being applied to solve a wide variety of problems. Separate analytics have been prepared for each chapter.

  4. CRITICAL REVIEW OF N, N{sup +}, N{sup +} {sub 2}, N{sup ++}, And N{sup ++} {sub 2} MAIN PRODUCTION PROCESSES AND REACTIONS OF RELEVANCE TO TITAN'S ATMOSPHERE

    SciTech Connect

    Dutuit, Odile; Thissen, Roland; Vuitton, Veronique; Canosa, Andre; Picard, Sebastien Le; Loison, Jean-Christophe; Ascenzi, Daniela; Tosi, Paolo; Franceschi, Pietro; Price, Stephen D.; Lavvas, Panayotis

    2013-02-15

    This paper is a detailed critical review of the production processes and reactions of N, N{sup +}, N{sup +} {sub 2}, N{sup ++}, and N{sup ++} {sub 2} of relevance to Titan's atmosphere. The review includes neutral, ion-molecule, and recombination reactions. The review covers all possible active nitrogen species under Titan's atmospheric conditions, specifically N{sub 2} (A {sup 3}{Sigma}{sup +} {sub u}), N ({sup 4} S), N ({sup 2} D), N ({sup 2} P), N{sup +} {sub 2}, N{sup +} ({sup 3} P), N{sup +} ({sup 1} D), N{sup ++} {sub 2}, and N{sup ++} species, and includes a critical survey of the reactions of N, N{sup +}, N{sup +} {sub 2}, N{sup ++}, and N{sup ++} {sub 2} with N{sub 2}, H{sub 2}, D{sub 2}, CH{sub 4}, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, C{sub 2}H{sub 6}, C{sub 3}H{sub 8} and the deuterated hydrocarbon analogs, as well as the recombination reactions of N{sup +} {sub 2}, N{sup +}, N{sup ++} {sub 2}, and N{sup ++}. Production processes, lifetimes, and quenching by collisions with N{sub 2} of all reactant species are reviewed. The N ({sup 4} S) state is reactive with radicals and its reactions with CH{sub 2}, CH{sub 3}, C{sub 2}H{sub 3}, and C{sub 2}H{sub 5} are reviewed. Metastable states N{sub 2} (A {sup 3}{Sigma}{sup +} {sub u}), N ({sup 2} D), and N ({sup 2} P) are either reactive or quenched by collisions with the target molecules reviewed. The reactions of N{sup +} ({sup 1} D) have similar rate constants as N{sup +} ({sup 3} P), but the product branching ratios differ significantly. Temperature effects and the role of the kinetic energy content of reactants are investigated. In all cases, experimental uncertainties of laboratory data are reported or estimated. Recommended values with uncertainties, or estimated values when no data are available, are given for rate constants and product branching ratios at 300 K and at the atmospheric temperature range of Titan (150-200 K for neutral reactions and 150 K for ion reactions).

  5. Positron production within our atmosphere

    NASA Astrophysics Data System (ADS)

    Dwyer, Joseph

    2016-04-01

    Positrons are commonly produced within our atmosphere by cosmic rays and the decay radioactive isotopes. Energetic positrons are also produced by pair production from the gamma rays generated by relativistic runaway electrons. Indeed, such positrons have been detected in Terrestrial Electron Beams (TEBs) in the inner magnetosphere by Fermi/GBM. In addition, positrons play an important role in relativistic feedback discharges (also known as dark lightning). Relativistic feedback models suggest that these discharges may be responsible for Terrestrial Gamma-ray Flashes (TGFs) and some gamma-ray glows. When producing TGFs, relativistic feedback discharges may generate large, lightning-like currents with current moments reaching hundreds of kA-km. In addition, relativistic feedback discharges also may limit the electric field that is possible in our atmosphere, affecting other mechanisms for generating runaway electrons. It is interesting that positrons, often thought of as exotic particles, may play an important role in thunderstorm processes. In this presentation, the role of positrons in high-energy atmospheric physics will be discussed. The unusual observation of positron clouds inside a thunderstorm by the ADELE instrument on an NCAR/NSF Gulfstream V aircraft will also be described. These observations illustrate that we still have much to learn about positron production within our atmosphere.

  6. Possible atmospheric lifetimes and chemical reaction mechanisms for selected HCFCs, HFCs, CH3CCl3, and their degradation products against dissolution and/or degradation in seawater and cloudwater

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Chameides, W. L.

    1990-01-01

    For a wide variety of atmospheric species including CO2, HNO3, and SO2, dissolution in seawater or cloudwater followed by hydrolysis or chemical reaction represents a primary pathway for removal from the atmosphere. In order to determine if this mechanism can also remove significant amounts of atmospheric chlorofluorocarbons (HCFC's), fluorocarbons (HFC's), and their degradation products, an investigation was undertaken as part of the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS). In this investigation, the rates at which CHCl2CF3 (HCFC-123), CCl2FCH3 (HCFC-141b), CClF2CH3 (HCFC-142b), CHClF2 (HCFC-22), CHClFCF3 (HCFC-124) CH2FCF3 (HFC-134a) CHF2CH3 (HFC-152a), CHF2CF3 (HFC-125), and CH3CCl3 can be dissolved in the oceans and in cloudwater were estimated from the species' thermodynamic and chemical properties using simple mathematical formulations to simulate the transfer of gases from the atmosphere to the ocean or cloudwater. The ability of cloudwater and rainwater to remove gas phase degradation products of these compounds was also considered as was the aqueous phase chemistry of the degradation products. The results of this investigation are described.

  7. A laboratory flow reactor with gas particle separation and on-line MS/MS for product identification in atmospherically important reactions

    NASA Astrophysics Data System (ADS)

    Bennett, J. F.; Collin, F.; Hastie, D. R.

    2009-06-01

    A system to study the gas and particle phase products from gas phase hydrocarbon oxidation is described. It consists of a gas phase photochemical flow reactor followed by a diffusion membrane denuder to remove gases from the reacted products, or a filter to remove the particles. Chemical analysis is performed by an atmospheric pressure chemical ionization (APCI) triple quadrupole mass spectrometer. A diffusion membrane denuder is shown to remove trace gases to below detectable limits so the particle phase can be studied. The system was tested by examining the products of the oxidation of m-xylene initiated by HO radicals. Dimethylphenol was observed in both the gas and particle phases although individual isomers could not be identified. Two furanone isomers, 5-methyl-2(3H)furanone and 3-methyl-2(5H)furanone were identified in the particulate phase, but the isobaric product 2,5 furandione was not observed. One isomer of dimethyl-nitrophenol was identified in the particle phase but not in the gas phase.

  8. A laboratory flow reactor with gas particle separation and on-line MS/MS for product identification in atmospherically important reactions

    NASA Astrophysics Data System (ADS)

    Bennett, J. F.; Collin, F.; Hastie, D. R.

    2009-12-01

    A system to study the gas and particle phase products from gas phase hydrocarbon oxidation is described. It consists of a gas phase photochemical flow reactor followed by a diffusion membrane denuder to remove gases from the reacted products, or a filter to remove the particles. Chemical analysis is performed by an atmospheric pressure chemical ionization (APCI) triple quadrupole mass spectrometer. A diffusion membrane denuder is shown to remove trace gases to below detectable limits so the particle phase can be studied. The system was tested by examining the products of the oxidation of m-xylene initiated by HO radicals. Dimethylphenol was observed in both the gas and particle phases although individual isomers could not be identified. Two furanone isomers, 5-methyl-2(3H)furanone and 3-methyl-2(5H)furanone were identified in the particulate phase, but the isobaric product 2,5 furandione was not observed. One isomer of dimethyl-nitrophenol was identified in the particle phase but not in the gas phase.

  9. Effect of temperature oscillation on chemical reaction rates in the atmosphere

    NASA Technical Reports Server (NTRS)

    Eberstein, I. J.

    1974-01-01

    The effect of temperature fluctuations on atmospheric ozone chemistry is examined by considering the Chapman photochemical theory of ozone transport to calculate globally averaged ozone production rates from mean reaction rates, activation energies, and recombination processes.

  10. A Computational Study of Acid Catalyzed Aerosol Reactions of Atmospherically Relevant Epoxides

    EPA Science Inventory

    Epoxides are important intermediates of atmospheric isoprene oxidation. Their subsequent reactions in the particle phase lead to the production of organic compounds detected in ambient aerosols. We apply density functional theory to determine the important kinetic factors that ...

  11. Atmospheric pressure microwave assisted heterogeneous catalytic reactions.

    PubMed

    Chemat-Djenni, Zoubida; Hamada, Boudjema; Chemat, Farid

    2007-01-01

    The purpose of the study was to investigate microwave selective heating phenomena and their impact on heterogeneous chemical reactions. We also present a tool which will help microwave chemists to answer to such questions as "My reaction yields 90% after 7 days at reflux; is it possible to obtain the same yield after a few minutes under microwaves?" and to have an approximation of their reactions when conducted under microwaves with different heterogeneous procedures. This model predicting reaction kinetics and yields under microwave heating is based on the Arrhenius equation, in agreement with experimental data and procedures. PMID:17909495

  12. Determination of the photolysis rate coefficient of monochlorodimethyl sulfide (MClDMS) in the atmosphere and its implications for the enhancement of SO2 production from the DMS + Cl2 reaction.

    PubMed

    Copeland, G; Lee, E P F; Williams, R G; Archibald, A T; Shallcross, D E; Dyke, J M

    2014-01-01

    In this work, the photolysis rate coefficient of CH3SCH2Cl (MClDMS) in the lower atmosphere has been determined and has been used in a marine boundary layer (MBL) box model to determine the enhancement of SO2 production arising from the reaction DMS + Cl2. Absorption cross sections measured in the 28000-34000 cm(-1) region have been used to determine photolysis rate coefficients of MClDMS in the troposphere at 10 solar zenith angles (SZAs). These have been used to determine the lifetimes of MClDMS in the troposphere. At 0° SZA, a photolysis lifetime of 3-4 h has been obtained. The results show that the photolysis lifetime of MClDMS is significantly smaller than the lifetimes with respect to reaction with OH (≈ 4.6 days) and with Cl atoms (≈ 1.2 days). It has also been shown, using experimentally derived dissociation energies with supporting quantum-chemical calculations, that the dominant photodissocation route of MClDMS is dissociation of the C-S bond to give CH3S and CH2Cl. MBL box modeling calculations show that buildup of MClDMS at night from the Cl2 + DMS reaction leads to enhanced SO2 production during the day. The extra SO2 arises from photolysis of MClDMS to give CH3S and CH2Cl, followed by subsequent oxidation of CH3S. PMID:24280000

  13. Atmospheric oxidation of 1,3-butadiene: characterization of gas and aerosol reaction products and implications for PM2.5

    NASA Astrophysics Data System (ADS)

    Jaoui, M.; Lewandowski, M.; Docherty, K.; Offenberg, J. H.; Kleindienst, T. E.

    2014-12-01

    Secondary organic aerosol (SOA) was generated by irradiating 1,3-butadiene (13BD) in the presence of H2O2 or NOx. Experiments were conducted in a smog chamber operated in either flow or batch mode. A filter/denuder sampling system was used for simultaneously collecting gas- and particle-phase products. The chemical composition of the gas phase and SOA was analyzed using derivative-based methods (BSTFA, BSTFA + PFBHA, or DNPH) followed by gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography (HPLC) analysis of the derivative compounds. The analysis showed the occurrence of more than 60 oxygenated organic compounds in the gas and particle phases, of which 31 organic monomers were tentatively identified. The major identified products include glyceric acid, d-threitol, erythritol, d-threonic acid, meso-threonic acid, erythrose, malic acid, tartaric acid, and carbonyls including glycolaldehyde, glyoxal, acrolein, malonaldehyde, glyceraldehyde, and peroxyacryloyl nitrate (APAN). Some of these were detected in ambient PM2.5 samples, and could potentially serve as organic markers of 13BD. Furthermore, a series of oligoesters were detected and found to be produced through chemical reactions occurring in the aerosol phase between compounds bearing alcoholic groups and compounds bearing acidic groups. SOA was analyzed for organic mass to organic carbon (OM /OC) ratio, effective enthalpy of vaporization (Δ Hvapeff), and aerosol yield. The average OM /OC ratio and SOA density were 2.7 ± 0.09 and 1.2 ± 0.05, respectively. The average Δ Hvapeff was -26.08 ± 1.46 kJ mol-1, a value lower than that of isoprene SOA. The average laboratory SOA yield measured in this study at aerosol mass concentrations between 22.5 and 140.2 μg m-3 was 0.025 ± 0.011, a value consistent with the literature (0.021-0.178). While the focus of this study has been examination of the particle-phase measurements, the gas-phase photooxidation products have also been

  14. Atmospheric oxidation of 1,3-butadiene: characterization of gas and aerosol reaction products and implication for PM2.5

    NASA Astrophysics Data System (ADS)

    Jaoui, M.; Lewandowski, M.; Docherty, K.; Offenberg, J. H.; Kleindienst, T. E.

    2014-06-01

    Secondary organic aerosol (SOA) was generated by irradiating 1,3-butadiene (13BD) in the presence of H2O2 or NOx. Experiments were conducted in a smog chamber operated in either flow or batch mode. A filter/denuder sampling system was used for simultaneously collecting gas- and particle-phase products. The chemical composition of the gas phase and SOA was analyzed using derivative-based methods (BSTFA, BSTFA + PFBHA, or DNPH) followed by gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography (HPLC) analysis of the derivative compounds. The analysis showed the occurrence of more than 60 oxygenated organic compounds in the gas and particle phases, of which 31 organic monomers were tentatively identified. The major identified products include glyceric acid, d-threitol, erythritol, d-threonic acid, meso-threonic acid, erythrose, malic acid, tartaric acid, and carbonyls including glycolaldehyde, glyoxal, acrolein, malonaldehyde, glyceraldehyde, and peroxyacryloyl nitrate (APAN). Some of these were detected in ambient PM2.5 samples and could potentially serve as organic markers of 1,3-butadiene (13BD). Furthermore, a series of oligoesters were detected and found to be produced from esterification reactions among compounds bearing alcoholic groups and compounds bearing acidic groups. Time profiles are provided for selected compounds. SOA was analyzed for organic mass to organic carbon (OM / OC) ratio, effective enthalpy of vaporization (ΔHvapeff), and aerosol yield. The average OM / OC ratio and SOA density were 2.7 ± 0.09 and 1.2 ± 0.05, respectively. The average ΔHvapeff was 26.1 ± 1.5 kJ mol-1, a value lower than that of isoprene SOA. The average laboratory SOA yield measured in this study at aerosol mass concentrations between 22.5 and 140.2 μg m-3 was 0.025 ± 0.011, a value consistent with the literature (0.021-0.178). While the focus of this study has been examination of the particle-phase measurements, the gas

  15. Atmospheric Chemistry: Laboratory Studies of Kinetics of Important Reactions.

    NASA Astrophysics Data System (ADS)

    Smith, S. J.

    Available from UMI in association with The British Library. Requires signed TDF. This thesis describes the experiments to measure the rate constants for some reactions of the atmospherically important nitrate radical (NO_3) using the discharge-flow technique. The nitrate radical was monitored by optical absorption at lambda = 662 nm. The reactions of NO_3 with some stable organic and inorganic substrates are reported. The temperature dependences of some of the rate constants have also been determined (298 < T < 523 K). In most cases, computer simulation was used to extract the rate constant for the primary process because the time-dependent behaviour of (NO_3) was affected by secondary reactions of NO_3 with products of the primary interaction. The Arrhenius parameter in parentheses (E _{rm a}/kJ mol^ {-1}, A/cm^3 molecule ^{-1}s^ {-1} respectively) for the following reactions have been determined: ethane (37, 6.7 times 10^{-12}), ethylene (25.8, 6.3 times 10^ {-12}), CH_3OH (21.3, 1.2 times 10^ {-12}), CHCiota_3 (23.4, 8.6 times 10 ^{-13}) and HCl (27.7, 4 times 10^{-12}). The activation energies for the reactions studied between NO_3 and some alkynes are represented well by the value 25 +/- 3 kJ mol^{-1} and the corresponding pre-exponential factors (expressed as ln(10 ^{13}A/cm^3 molecule^{-1}s ^{-1}) are as follows: C_2H_2 (1.6 +/- 1.4), C_3H _4 (5.0 +/- 1.4), 1-C_4H_6 (5.8 +/- 1.0), 1-C_5 H_8 (5.7 +/- 0.6) and 1-C_6H _{10} (4.5 +/- 0.4). Some reactions were studied at room temperature _3(298 +/- 2 K) only and the rate constants found (in units of cm ^3 molecule^{ -1}s^{-1}) are: buta-1,3-diene (1.8 times 10 ^{-13}), isobutene (2.8 times 10^{-13 }), HBr (1.3 times 10 ^{-15}) and hex-2-yne (3.0 times 10^{-14 }). Non-Arrhenius behaviour was found in the reactions of NO_3 with n-butane, isobutane and propene. The empirical variation of these rate constants with temperature is well represented by the three parameter expressions:. k(T) = 1.2 times 10 ^{-46}T^{11

  16. A flexible transition state searching method for atmospheric reaction systems

    NASA Astrophysics Data System (ADS)

    Lin, Xiao-Xiao; Liu, Yi-Rong; Huang, Teng; Chen, Jiao; Jiang, Shuai; Huang, Wei

    2015-04-01

    The precise and rapid exploration of transition states (TSs) is a major challenge when studying atmospheric reactions due to their complexity. In this work, a Monte Carlo Transition State Search Method (MCTSSM), which integrates Monte Carlo sampling technique with transition state optimization methods using an efficient computer script, has been developed for transition state searches. The efficiency and the potential application in atmospheric reactions of this method have been demonstrated by three types of test suits related to the reactions of atmospheric volatile organic compounds (VOCs): (1) OH addition, (2) OH hydrogen-abstraction, and (3) the other reactive group (e.g. Cl, O3, NO3), especially for the reaction of β-pinene-sCI (stabilized Criegee Intermediates) with water. It was shown that the application of this method with effective restricted parameters has greatly simplified the time-consuming and tedious manual search procedure for transition state (TS) of the bimolecular reaction systems.

  17. A Flexible Transition State Searching Method for Atmospheric Reaction Systems

    SciTech Connect

    Lin, Xiao-Xiao; Liu, Yi-Rong; Huang, Teng; Chen, Jiao; Jiang, Shuai; Huang, Wei

    2015-04-01

    The precise and rapid exploration of transition states (TSs) is a major challenge when studying atmospheric reactions due to their complexity. In this work, a Monte Carlo Transition State Search Method (MCTSSM), which integrates Monte Carlo sampling technique with transition state optimization methods using an efficient computer script, has been developed for transition state searches. The efficiency and the potential application in atmospheric reactions of this method have been demonstrated by three types of test suits related to the reactions of atmospheric volatile organic compounds (VOCs): (1) OH addition, (2) OH hydrogen-abstraction, and (3) the other reactive group (e.g. Cl, O3, NO3), especially for the reaction of β-pinene-sCI (stabilized Criegee Intermediates) with water. It was shown that the application of this method with effective restricted parameters has greatly simplified the time-consuming and tedious manual search procedure for transition state (TS) of the bimolecular reaction systems.

  18. Real-time air monitoring of mustard gas and Lewisite 1 by detecting their in-line reaction products by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow ion introduction.

    PubMed

    Okumura, Akihiko; Takada, Yasuaki; Watanabe, Susumu; Hashimoto, Hiroaki; Ezawa, Naoya; Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Kondo, Tomohide; Nagashima, Hisayuki; Nagoya, Tomoki

    2015-01-20

    A new method enabling sensitive real-time air monitoring of highly reactive chemical warfare agents, namely, mustard gas (HD) and Lewisite 1 (L1), by detecting ions of their in-line reaction products instead of intact agents, is proposed. The method is based on corona discharge-initiated atmospheric pressure chemical ionization coupled with ion trap tandem mass spectrometry (MS(n)) via counterflow ion introduction. Therefore, it allows for highly sensitive and specific real-time detection of a broad range of airborne compounds. In-line chemical reactions, ionization reactions, and ion fragmentations of these agents were investigated. Mustard gas is oxygenated in small quantity by reactive oxygen species generated in the corona discharge. With increasing air humidity, the MS(2) signal intensity of protonated molecules of mono-oxygenated HD decreases but exceeds that of dominantly existing intact HD. This result can be explained in view of proton affinity. Lewisite 1 is hydrolyzed and oxidized. As the humidity increases from zero, the signal of the final product, namely, didechlorinated, dihydroxylated, and mono-oxygenated L1, quickly increases and reaches a plateau, giving the highest MS(2) and MS(3) signals among those of L1 and its reaction products. The addition of minimal moisture gives the highest signal intensity, even under low humidity. The method was demonstrated to provide sufficient analytical performance to meet the requirements concerning hygienic management and counter-terrorism. It will be the first practical method, in view of sensitivity and specificity, for real-time air monitoring of HD and L1 without sample pretreatment. PMID:25553788

  19. Reaction products of chlorine dioxide.

    PubMed Central

    Stevens, A A

    1982-01-01

    Inspection of the available literature reveals that a detailed investigation of the aqueous organic chemistry of chlorine dioxide and systematic identification of products formed during water disinfection has not been considered. This must be done before an informed assessment can be made of the relative safety of using chlorine dioxide as a disinfectant alternative to chlorine. Although trihalomethanes are generally not formed by the action of chlorine dioxide, the products of chlorine dioxide treatment of organic materials are oxidized species, some of which also contain chlorine. The relative amounts of species types may depend on the amount of chlorine dioxide residual maintained and the concentration and nature of the organic material present in the source water. The trend toward lower concentrations of chlorinated by-products with increasing ClO2 concentration, which was observed with phenols, has not been observed with natural humic materials as measured by the organic halogen parameter. Organic halogen concentrations have been shown to increase with increasing chlorine dioxide dose, but are much lower than those observed when chlorine is applied. Aldehydes have been detected as apparent by-products of chlorine dioxide oxidation reactions in a surface water that is a drinking water source. Some other nonchlorinated products of chlorine dioxide treatment may be quinones and epoxides. The extent of formation of these moieties within the macromolecular humic structure is also still unknown. PMID:7151750

  20. Heterogeneous reactions important in atmospheric ozone depletion: a theoretical perspective.

    PubMed

    Bianco, Roberto; Hynes, James T

    2006-02-01

    Theoretical studies of the mechanisms of several heterogeneous reactions involving ClONO(2), H(2)O, HCl, HBr, and H(2)SO(4) important in atmospheric ozone depletion are described, focused primarily on reactions on aqueous aerosol surfaces. Among the insights obtained is the active chemical participation of the surface water molecules in several of these reactions. The general methodology adopted allows reduction of these complex chemical problems to meaningful model systems amenable to quantum chemical calculations. PMID:16489736

  1. Role of Double Hydrogen Atom Transfer Reactions in Atmospheric Chemistry.

    PubMed

    Kumar, Manoj; Sinha, Amitabha; Francisco, Joseph S

    2016-05-17

    Hydrogen atom transfer (HAT) reactions are ubiquitous and play a crucial role in chemistries occurring in the atmosphere, biology, and industry. In the atmosphere, the most common and traditional HAT reaction is that associated with the OH radical abstracting a hydrogen atom from the plethora of organic molecules in the troposphere via R-H + OH → R + H2O. This reaction motif involves a single hydrogen transfer. More recently, in the literature, there is an emerging framework for a new class of HAT reactions that involves double hydrogen transfers. These reactions are broadly classified into four categories: (i) addition, (ii) elimination, (iii) substitution, and (iv) rearrangement. Hydration and dehydration are classic examples of addition and elimination reactions, respectively whereas tautomerization or isomerization belongs to a class of rearrangement reactions. Atmospheric acids and water typically mediate these reactions. Organic and inorganic acids are present in appreciable levels in the atmosphere and are capable of facilitating two-point hydrogen bonding interactions with oxygenates possessing an hydroxyl and/or carbonyl-type functionality. As a result, acids influence the reactivity of oxygenates and, thus, the energetics and kinetics of their HAT-based chemistries. The steric and electronic effects of acids play an important role in determining the efficacy of acid catalysis. Acids that reduce the steric strain of 1:1 substrate···acid complex are generally better catalysts. Among a family of monocarboxylic acids, the electronic effects become important; barrier to the catalyzed reaction correlates strongly with the pKa of the acid. Under acid catalysis, the hydration of carbonyl compounds leads to the barrierless formation of diols, which can serve as seed particles for atmospheric aerosol growth. The hydration of sulfur trioxide, which is the principle mechanism for atmospheric sulfuric acid formation, also becomes barrierless under acid catalysis

  2. Atmospheric reactions of N-nitrosodimethylamine and dimethylnitramine

    SciTech Connect

    Tuazon, E.C.; Carter, W.P.L.; Atkinson, R.; Winer, A.M.; Pitts, J.N. Jr.

    1984-01-01

    The major atmospheric reactions of N-nitrosodimethylamine (NDMA) and dimethylnitramine (DMN) have been investigated in an approx.3500-L environmental chamber utilizing in situ long-path Fourier transform infrared spectroscopy. Rate constants for the reactions of OH radicals with NDMA and DMN were measured relative to that for dimethyl ether at 298 +/- 2K and resulted in values of k(OH + NDMA) = (3.0 +/- 0.4) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/ and k(OH + DMN) = (4.5 +/- 0.5) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/. Rate constants for the reactions of O/sub 3/ with NDMA and DMN were determined to be less than or equal to 1 x 10/sup -20/ and less than or equal to 3 x 10/sup -21/ cm/sup 3/ molecule/sup -1/ s/sup -1/, respectivley. The photolysis rate NDMA measured in the presence of excess O/sub 3/ indicated the photodissociation quantum yield to be unity for lambda >/approx.290 nm. The photolysis of NDMA in O/sub 3/ resulted in the formation of approx.65% DMN together with lesser yields of HCHO, CH/sub 3/NO/sub 2/, and CO. A mechanism accounting for the observed products is presented. The rapid photolysis of NDMA leads to a tropospheric half-life of only approx.5 min, while a half-life of approx.2 days is predicted for DMN, with its major removal process being reaction with OH radicals.

  3. Atmospheric reactions on electrically charged surfaces.

    PubMed

    Phillips, Leon F

    2013-07-14

    It is proposed that tropospheric NO2 at concentrations in the parts-per-billion range can be efficiently converted to HONO in a dust storm, by a process that is initiated by electron capture by NO2 from a negatively-charged dust particle. The electron capture is visualized as a harpoon-type process that does not require the NO2 to be adsorbed on the particle. The resulting electronically excited [NO2(-)]* ion reacts with water to form an HONO molecule plus an OH(-)·(H2O)n cluster ion. It is suggested that analogous processes can occur on other atmospheric aerosol particles with both positive and negative charges, with other molecules of high electron affinity such as SO2, and also, because the earth's surface is effectively the negative plate of a planet-sized capacitor, at the surfaces of terrestrial solids, lakes and oceans. PMID:23689618

  4. Atmospheric chemistry of CF3CF═CH2 and (Z)-CF3CF═CHF: Cl and NO3 rate coefficients, Cl reaction product yields, and thermochemical calculations.

    PubMed

    Papadimitriou, Vassileios C; Lazarou, Yannis G; Talukdar, Ranajit K; Burkholder, James B

    2011-01-20

    Rate coefficients, k, for the gas-phase reactions of Cl atoms and NO(3) radicals with 2,3,3,3-tetrafluoropropene, CF(3)CF═CH(2) (HFO-1234yf), and 1,2,3,3,3-pentafluoropropene, (Z)-CF(3)CF═CHF (HFO-1225ye), are reported. Cl-atom rate coefficients were measured in the fall-off region as a function of temperature (220-380 K) and pressure (50-630 Torr; N(2), O(2), and synthetic air) using a relative rate method. The measured rate coefficients are well represented by the fall-off parameters k(0)(T) = 6.5 × 10(-28) (T/300)(-6.9) cm(6) molecule(-2) s(-1) and k(∞)(T) = 7.7 × 10(-11) (T/300)(-0.65) cm(3) molecule(-1) s(-1) for CF(3)CF═CH(2) and k(0)(T) = 3 × 10(-27) (T/300)(-6.5) cm(6) molecule(-2) s(-1) and k(∞)(T) = 4.15 × 10(-11) (T/300)(-0.5) cm(3) molecule(-1) s(-1) for (Z)-CF(3)C═CHF with F(c) = 0.6. Reaction product yields were measured in the presence of O(2) to be (98 ± 7)% for CF(3)C(O)F and (61 ± 4)% for HC(O)Cl in the CF(3)CF═CH(2) reaction and (108 ± 8)% for CF(3)C(O)F and (112 ± 8)% for HC(O)F in the (Z)-CF(3)CF═CHF reaction, where the quoted uncertainties are 2σ (95% confidence level) and include estimated systematic errors. NO(3) reaction rate coefficients were determined using absolute and relative rate methods. Absolute measurements yielded upper limits for both reactions between 233 and 353 K, while the relative rate measurements yielded k(3)(295 K) = (2.6 ± 0.25) × 10(-17) cm(3) molecule(-1) s(-1) and k(4)(295 K) = (4.2 ± 0.5) × 10(-18) cm(3) molecule(-1) s(-1) for CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF, respectively. The Cl-atom reaction with CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF leads to decreases in their atmospheric lifetimes and global warming potentials and formation of a chlorine-containing product, HC(O)Cl, for CF(3)CF═CH(2). The NO(3) reaction has been shown to have a negligible impact on the atmospheric lifetimes of CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF. The energetics for the reaction of Cl, NO(3), and OH with CF

  5. Heterogeneous reactions of volatile organic compounds in the atmosphere

    NASA Astrophysics Data System (ADS)

    Shen, Xiaoli; Zhao, Yue; Chen, Zhongming; Huang, Dao

    2013-04-01

    Volatile organic compounds (VOCs) are of central importance in the atmosphere because of their close relation to air quality and climate change. As a significant sink for VOCs, the fate of VOCs via heterogeneous reactions may explain the big gap between field and model studies. These reactions play as yet unclear but potentially crucial role in atmospheric processes. In order to better evaluate this reaction pathway, we present the first specific review for the progress of heterogeneous reaction studies on VOCs, including carbonyl compounds, organic acids, alcohols, and so on. Our review focuses on the processes for heterogeneous reactions of VOCs under varying experimental conditions, as well as their implications for trace gas and HOx budget, secondary organic aerosol (SOA) formation, physicochemical properties of aerosols, and human health. Finally, we propose the future direction for laboratory studies of heterogeneous chemistry of VOCs that should be carried out under more atmospherically relevant conditions, with a special emphasis on the effects of relative humidity and illumination, the multicomponent reaction systems, and reactivity of aged and authentic particles. In particular, more reliable uptake coefficients, based on the abundant elaborate laboratory studies, appropriate calibration, and logical choice criterion, are urgently required in atmospheric models.

  6. Laboratory investigation of chemical reactions relevant in Titan atmosphere

    NASA Astrophysics Data System (ADS)

    Franceschi, P.; Ascenzi, D.; Guella, G.; Scarduelli, G.; Tosi, P.

    Experimental data obtained by the Huygens-Cassini mission demonstrate the chemical complexity of the Titan's atmosphere. To rationalize such a complexity it is important to set-up laboratory investigations of the chemical processes occurring in the energetic processing of hydrocarbon nitrogen mixtures followed by the detailed study of selected key reactions. In laboratory, energetic conditions can be simulated in the plasma treatment of hydrocarbon-nitrogen samples and molecular synthesis as well as polymerization can be observed [1]. In the last months we investigated the dynamics of non equilibrium discharges containing benzene focusing on the growth of complex molecular systems [2]. Our study has been performed combining well established analytical methods for neutral product detection with mass spectrometric analysis of the ion population. In this communication, preliminary results on the molecular growth in nitrogen-hydrocarbon plasma processes will be presented and the dynamics of the C6 H+ + C6 H6 reaction will be discussed. 5 References [1] R. Hodyss, Methods for the analysis of organic chemistry on Titan, Phd Dissertation, California Institute of Technology (2005). [2] G. Guella, D. Ascenzi, P. Franceschi, P. Tosi, Rapid Commun. Mass Spectrom. 19, 1-6 (2005).

  7. Kinetics, mechanisms and products of reactions of Criegee intermediates

    NASA Astrophysics Data System (ADS)

    Orr-Ewing, Andrew

    The atmospheric ozonolysis of alkenes such as isoprene produces Criegee intermediates which are increasingly recognized as important contributors to oxidation chemistry in the Earth's troposphere. Stabilized Criegee intermediates are conveniently produced in the laboratory by ultraviolet photolysis of diiodoalkanes in the presence of O2, and can be detected by absorption spectroscopy using their strong electronic bands in the near ultraviolet region. We have used these techniques to study a wide range of reactions of Criegee intermediates, including their self-reactions, and reactions with carboxylic acids and various other trace atmospheric constituents. In collaboration with the Sandia National Laboratory group led by Drs C.A. Taatjes and D.L. Osborn, we have used photoionization and mass spectrometry methods, combined with electronic structure calculations, to characterize the products of several of these reactions. Our laboratory studies determine rate coefficients for the Criegee intermediate reactions, many of which prove to be fast. In the case of reactions with carboxylic acids, a correlation between the dipole moments of the reactants and the reaction rate coefficients suggests a dipole-capture controlled reaction and allows us to propose a structure-activity relationship to predict the rates of related processes. The contributions of these various Criegee intermediate reactions to the chemistry of the troposphere have been assessed using the STOCHEM-CRI global atmospheric chemistry model. This work was supported by NERC grant NE/K004905/1.

  8. Theoretical study on the mechanism and kinetics of acetaldehyde and hydroperoxyl radical: An important atmospheric reaction

    NASA Astrophysics Data System (ADS)

    Farnia, Solaleh; Vahedpour, Morteza; Abedi, Mostafa; Farrokhpour, Hossein

    2013-09-01

    A systematic theoretical study was performed on the mechanism and kinetics of the atmospheric reaction of acetaldehyde (CH3CHO) and hydroperoxyl radical (HO2) in the gas phase. The DFT-B3LYP/6-311++G(3df,3pd) and CCSD(T)/6-311++G(d,p) methods were employed for calculations. Based on the calculations, this reaction leads to four different products through radical addition and hydrogen abstraction mechanisms which are very important in atmospheric and combustion chemistry. The favorable reaction paths begin with α-hydroxyethylperoxy radical, CH3CH(OO)OH, in a exothermic process and finally leads to the product P1 (CH3COOH + OH). The overall rate constants for favorite reaction paths have been calculated at different temperatures (200-2500 K).

  9. Reaction Kinetics of Meteoric Sodium Reservoirs in the Upper Atmosphere.

    PubMed

    Gómez Martín, J C; Garraway, S A; Plane, J M C

    2016-03-10

    The gas-phase reactions of a selection of sodium-containing species with atmospheric constituents, relevant to the chemistry of meteor-ablated Na in the upper atmosphere, were studied in a fast flow tube using multiphoton ionization time-of-flight mass spectrometry. For the first time, unambiguous observations of NaO and NaOH in the gas phase under atmospheric conditions have been achieved. This enabled the direct measurement of the rate constants for the reactions of NaO with H2, H2O, and CO, and of NaOH with CO2, which at 300-310 K were found to be (at 2σ confidence level): k(NaO + H2O) = (2.4 ± 0.6) × 10(-10) cm(3) molecule (-1) s(-1), k(NaO + H2) = (4.9 ± 1.2) × 10(-12) cm(3) molecule (-1) s(-1), k(NaO + CO) = (9 ± 4) × 10(-11) cm(3) molecule (-1) s(-1), and k(NaOH + CO2 + M) = (7.6 ± 1.6) × 10(-29) cm(6) molecule (-2) s(-1) (P = 1-4 Torr). The NaO + H2 reaction was found to make NaOH with a branching ratio ≥ 99%. A combination of quantum chemistry and statistical rate theory calculations are used to interpret the reaction kinetics and extrapolate the atmospherically relevant experimental results to mesospheric temperatures and pressures. The NaO + H2O and NaOH + CO2 reactions act sequentially to provide the major atmospheric sink of meteoric Na and therefore have a significant impact on the underside of the Na layer in the terrestrial mesosphere: the newly determined rate constants shift the modeled peak to about 93 km, i.e., 2 km higher than observed by ground-based lidars. This highlights further uncertainties in the Na chemistry cycle such as the unknown rate constant of the NaOH + H reaction. The fast Na-recycling reaction between NaO and CO and a re-evaluated rate constant of the NaO + CO2 sink should be now considered in chemical models of the Martian Na layer. PMID:25723735

  10. Atmospheric products from the Upper Atmosphere Research Satellite (UARS)

    NASA Technical Reports Server (NTRS)

    Ahmad, Suraiya P.; Johnson, James E.; Jackman, Charles H.

    2003-01-01

    This paper provides information on the products available at the NASA Goddard Earth Sciences (GES) Distributed Active Archive Center (DAAC) from the Upper Atmosphere Research Satellite (UARS) mission. The GES DAAC provides measurements from the primary UARS mission, which extended from launch in September 1991 through September 2001. The ten instruments aboard UARS provide measurements of atmospheric trace gas species, dynamical variables, solar irradiance input, and particle energy flux. All standard Level 3 UARS products from all ten instruments are offered free to the public and science user community. The Level 3 data are geophysical parameters, which have been transformed into a common format and equally spaced along the measurement trajectory. The UARS data have been reprocessed several times over the years following improvements to the processing algorithms. The UARS data offered from the GES DAAC are the latest versions of each instrument. The UARS data may be accessed through the GES DAAC website at

  11. Photochemical reactions of cyanoacetylene and dicyanoacetylene: Possible processes in Titan's atmosphere

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Guillemin, J. C.

    1991-01-01

    Titan has an atmosphere which is subject to dramatic chemical evolution due mainly to the dramatic effect of the UV flux from the Sun. The energetic solar photons and other particles are converting the methane-nitrogen atmosphere into the unsaturated carbon compounds observed by the Voyager probes. These same solar photons are also converting some of these unsaturated reaction products into the aerosols observed in the atmosphere which obscure the view of the surface of Titan. In particular, the photochemical reactions of cyanoacetylene, dicyanoacetylene, acetylene and ethylene may result in the formation of the higher hydrocarbons and polymers which result in the aerosols observed in Titan's atmosphere. Polymers are the principal reaction products formed by irradiation of cyanoacetylene and dicyanoacetylene. Irradiation of cyanoacetylene with 185 nm of light also yields 1,3,5-tricyanobenzene while irradiation at 254 nm yields 1,2,4-tricyanobenzene and tetracyano cyclooctatetraenes. Photolyses of mixtures of cyanoacetylene and acetylene yields mono- and di- cyanobenzenes. The 1-Cyanocyclobutene is formed from the photochemical addition of cyanoacetylene with ethylene. The photolysis of dicyanoacetylene with acetylene yields 2,3-dicyano-1,3-butadiene and 1,2-dicyanobenzene. Tetracyano cyclooctatetraene products were also observed in the photolysis of mixtures of dicyanoacetylene and acetylene with 254 nm light. The 1,2-Dicyano cyclobutene is obtained from the photolysis dicyanoacetylene and ethylene. Reaction mechanisms will be proposed to explain the observed photoproducts.

  12. Insights into secondary reactions occurring during atmospheric ablation of micrometeoroids

    NASA Astrophysics Data System (ADS)

    Court, Richard W.; Tan, Jonathan

    2016-06-01

    Ablation of micrometeoroids during atmospheric entry yields volatile gases such as water, carbon dioxide, and sulfur dioxide, capable of altering atmospheric chemistry and hence the climate and habitability of the planetary surface. While laboratory experiments have revealed the yields of these gases during laboratory simulations of ablation, the reactions responsible for the generation of these gases have remained unclear, with a typical assumption being that species simply undergo thermal decomposition without engaging in more complex chemistry. Here, pyrolysis-Fourier transform infrared spectroscopy reveals that mixtures of meteorite-relevant materials undergo secondary reactions during simulated ablation, with organic matter capable of taking part in carbothermic reduction of iron oxides and sulfates, resulting in yields of volatile gases that differ from those predicted by simple thermal decomposition. Sulfates are most susceptible to carbothermic reduction, producing greater yields of sulfur dioxide and carbon dioxide at lower temperatures than would be expected from simple thermal decomposition, even when mixed with meteoritically relevant abundances of low-reactivity Type IV kerogen. Iron oxides were less susceptible, with elevated yields of water, carbon dioxide, and carbon monoxide only occurring when mixed with high abundances of more reactive Type III kerogen. We use these insights to reinterpret previous ablation simulation experiments and to predict the reactions capable of occurring during ablation of carbonaceous micrometeoroids in atmospheres of different compositions.

  13. Insights into secondary reactions occurring during atmospheric ablation of micrometeoroids

    NASA Astrophysics Data System (ADS)

    Court, Richard W.; Tan, Jonathan

    2016-05-01

    Ablation of micrometeoroids during atmospheric entry yields volatile gases such as water, carbon dioxide, and sulfur dioxide, capable of altering atmospheric chemistry and hence the climate and habitability of the planetary surface. While laboratory experiments have revealed the yields of these gases during laboratory simulations of ablation, the reactions responsible for the generation of these gases have remained unclear, with a typical assumption being that species simply undergo thermal decomposition without engaging in more complex chemistry. Here, pyrolysis-Fourier transform infrared spectroscopy reveals that mixtures of meteorite-relevant materials undergo secondary reactions during simulated ablation, with organic matter capable of taking part in carbothermic reduction of iron oxides and sulfates, resulting in yields of volatile gases that differ from those predicted by simple thermal decomposition. Sulfates are most susceptible to carbothermic reduction, producing greater yields of sulfur dioxide and carbon dioxide at lower temperatures than would be expected from simple thermal decomposition, even when mixed with meteoritically relevant abundances of low-reactivity Type IV kerogen. Iron oxides were less susceptible, with elevated yields of water, carbon dioxide, and carbon monoxide only occurring when mixed with high abundances of more reactive Type III kerogen. We use these insights to reinterpret previous ablation simulation experiments and to predict the reactions capable of occurring during ablation of carbonaceous micrometeoroids in atmospheres of different compositions.

  14. Atmospheric Production of Perchlorate on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Claire, M.; Catling, D. C.; Zahnle, K. J.

    2009-12-01

    Natural production and preservation of perchlorate on Earth occurs only in arid environments. Isotopic evidence suggests a strong role for atmospheric oxidation of chlorine species via pathways including ozone or its photochemical derivatives. As the Martian atmosphere is both oxidizing and drier than the driest places on Earth, we propose an atmospheric origin for the Martian perchlorates measured by NASA's Phoenix Lander. A variety of hypothetical formation pathways can be proposed including atmospheric photochemical reactions, electrostatic discharge, and gas-solid reactions. Here, we investigate gas phase formation pathways using a 1-D photochemical model (Catling et al. 2009, accepted by JGR). Because perchlorate-rich deposits in the Atacama desert are closest in abundance to perchlorate measured at NASA's Phoenix Lander site, we start with a study of the means to produce Atacama perchlorate. We found that perchlorate can be produced in sufficient quantities to explain the abundance of perchlorate in the Atacama from a proposed gas phase oxidation of chlorine volatiles to perchloric acid. These results are sensitive to estimated reaction rates for ClO3 species. The feasibility of gas phase production for the Atacama provides justification for further investigations of gas phase photochemistry as a possible source for Martian perchlorate. In addition to the Atacama results, we will present a preliminary study incorporating chlorine chemistry into an existing Martian photochemical model (Zahnle et al. JGR 2008).

  15. Atmospheric Reactions of a Series of Hexenols with OH Radical and Ozone

    NASA Astrophysics Data System (ADS)

    Gai, Yanbo; Lin, Xiaoxiao; Ma, Qiao; Yang, Chengqiang; Zhao, Weixiong; Zhang, Weijun

    2016-04-01

    C6 hexenols are one of the most significant groups of biogenic volatile organic compounds (BVOCs). Because of their antibacterial properties, C6 hexenols can be emitted by a wide number of plants in response to changes in the ambient environment. The oxidation of these compounds in the atmosphere is involved in the formation of tropospheric ozone and secondary organic aerosols (SOA), thus causing significant effects on atmospheric chemistry and the climate. The lack of corresponding kinetic parameters and product information of their oxidation reactions will result in incomplete atmospheric chemical mechanisms and models. In this paper, we will overview our recent research progress on the study of the atmospheric reactions of a series of C6 hexenols with OH radicals and ozone. A series of studies were conducted using both experimental and theoretical methods. Corresponding rate constants were obtained, and reaction mechanisms were also analyzed. It could be concluded that both the nature of the substituent and its position play a fundamental role in the reactivity of the C6 hexenols toward OH radicals and O3. An activating effect of the -OH group in OH radical reactions was found, thus making the H-abstraction channel non-negligible in reactions of these unsaturated alcohols with OH radicals. The removal of these C6 hexenols by ozone also showed great importance and could be competitive with the major recognized sinks by OH radicals. These studies are of great significance for understanding the mechanism of atmospheric chemical reactions of hexenols and improving the atmospheric chemistry model. Experimental detail and corresponding results will be presented. Acknowledgements. This work was supported by the National Natural Science Foundation of China (21307137, 41575125 and 91544228), and the Natural Science Foundation of Anhui Province (1508085J03).

  16. Heterogeneous Reactions in Atmospheric Aerosols Observed Using ATOFMS

    NASA Astrophysics Data System (ADS)

    Ryan, Sullivan

    2005-03-01

    The heterogeneous aging of natural atmospheric particles by reactive gases in the troposphere has been investigated in a flow-tube reactor using Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) to monitor changes in the particle composition in real-time. Sea- salt and mineral dust aerosols were introduced into the flow tube simultaneously and reacted with nitric acid in a relative rate experiment. ATOFMS is a single-particle technique and thus enables us to distinguish which particle type accumulates more nitric acid. This allows us to determine if the differing surface area or kinetics is driving the partitioning of nitric acid between the sea salt and dust. The results of these and other aerosol flow-tube kinetics experiments will be presented. The atmospheric implications will be emphasized, particularly in relation to observations made by ATOFMS of heterogeneous reactions occurring in particles over the Pacific Ocean during ACE-Asia.

  17. Genotoxicity testing of Maillard reaction products.

    PubMed

    Shibamoto, T

    1989-01-01

    Since the development of short-term genotoxicity tests such as the Ames assay, the mutagenicity of Maillard reaction products has been tested extensively. Some products have exhibited strong activity. For example, one of the earliest studies demonstrated some mutagenic activity in a dichloromethane extract of a D-glucose/ammonia Maillard model system. Many researchers have attempted to pinpoint the principal chemical(s) of mutagenicity of the Maillard products using various sugar-amino acid browning model systems over last two decades. However, no mutagenic individual Maillard product has been isolated and identified. Nitrite has been also used as a reactant in browning reaction model systems, primarily to investigate the formation of potentially mutagenic or carcinogenic N-nitroso compounds. Recently some potent mutagens isolated from pyrolyzed amino acids or proteins have begun to receive attention as Maillard reaction products. PMID:2675034

  18. Upper atmosphere research: Reaction rate and optical measurements

    NASA Technical Reports Server (NTRS)

    Stief, L. J.; Allen, J. E., Jr.; Nava, D. F.; Payne, W. A., Jr.

    1990-01-01

    The objective is to provide photochemical, kinetic, and spectroscopic information necessary for photochemical models of the Earth's upper atmosphere and to examine reactions or reactants not presently in the models to either confirm the correctness of their exclusion or provide evidence to justify future inclusion in the models. New initiatives are being taken in technique development (many of them laser based) and in the application of established techniques to address gaps in the photochemical/kinetic data base, as well as to provide increasingly reliable information.

  19. Chemical Characterization and Reactivity of Fuel-Oxidizer Reaction Product

    NASA Technical Reports Server (NTRS)

    David, Dennis D.; Dee, Louis A.; Beeson, Harold D.

    1997-01-01

    Fuel-oxidizer reaction product (FORP), the product of incomplete reaction of monomethylhydrazine and nitrogen tetroxide propellants prepared under laboratory conditions and from firings of Shuttle Reaction Control System thrusters, has been characterized by chemical and thermal analysis. The composition of FORP is variable but falls within a limited range of compositions that depend on three factors: the fuel-oxidizer ratio at the time of formation; whether the composition of the post-formation atmosphere is reducing or oxidizing; and the reaction or post-reaction temperature. A typical composition contains methylhydrazinium nitrate, ammonium nitrate, methylammonium nitrate, and trace amounts of hydrazinium nitrate and 1,1-dimethylhydrazinium nitrate. Thermal decomposition reactions of the FORP compositions used in this study were unremarkable. Neither the various compositions of FORP, the pure major components of FORP, nor mixtures of FORP with propellant system corrosion products showed any unusual thermal activity when decomposed under laboratory conditions. Off-limit thruster operations were simulated by rapid mixing of liquid monomethylhydrazine and liquid nitrogen tetroxide in a confined space. These tests demonstrated that monomethylhydrazine, methylhydrazinium nitrate, ammonium nitrate, or Inconel corrosion products can induce a mixture of monomethylhydrazine and nitrogen tetroxide to produce component-damaging energies. Damaging events required FORP or metal salts to be present at the initial mixing of monomethylhydrazine and nitrogen tetroxide.

  20. The OMI Atmospheric Science Data Products

    NASA Astrophysics Data System (ADS)

    Johnson, J. E.; Ahmad, S. P.; Levelt, P. F.; Bhartia, P. K.; Hilsenrath, E.; Leppelmeier, G. W.

    2003-12-01

    The Ozone Monitoring Instrument (OMI), will provide measurements in the UV and Visible spectral regions (1560 wavelength bands between 270 and 500 nm with approximately 0.5 nm spectral resolution). OMI will continue the long-term Total Ozone Mapping Spectrometer (TOMS) column ozone record and will focus on monitoring the ozone layer, ozone depleting trace gases (BrO and OClO), atmospheric pollutants (tropospheric ozone, NO2, SO2, and HCHO), clouds and aerosols characteristics, and surface spectral UV irradiance and erythemal surface UV-B flux. OMI is a contribution of the Netherlands Agency for Aerospace Programs (NIVR) in collaboration with the Finnish Meteorological Institute (FMI), to NASA's Aura mission. It will be flown on the Aura spacecraft (early 2004) in a sun-synchronous polar orbit with equator crossing time approximately at 1:38 p.m in the ascending mode. The standard atmospheric chemistry and dynamics products derived from OMI, and from the other two Aura sensors, the High Resolution Dynamics Limb Sounder (HIRDLS) and the Microwave Limb Sounder (MLS), will be archived at the NASA GES DAAC. OMI atmospheric data products will provide continuity to the over 30 year long-term ozone data records obtained from the heritage atmospheric data missions including Nimbus-4 BUV and Nimbus-7 SBUV, and a series of TOMS instruments, also archived at the NASA GES DAAC. The standard satellite data sets, as well as regional subsets, related ancillary data sets, and data analysis tools are freely available to the public for the Earth System Science studies, environmental applications, and educational use. This presentation will provide an overview of the OMI instrument, data processing, data products, and the data services provided by the NASA GES DAAC's Upper Atmosphere Data Support team to the user in the areas of accessing data products, documentation, browse, and data analysis software.

  1. Low Energy Nuclear Reaction Products at Surfaces

    NASA Astrophysics Data System (ADS)

    Nagel, David J.

    2008-03-01

    This paper examines the evidence for LENR occurring on or very near to the surface of materials. Several types of experimental indications for LENR surface reactions have been reported and will be reviewed. LENR result in two types of products, energy and the appearance of new elements. The level of instantaneous power production can be written as the product of four factors: (1) the total area of the surface on which the reactions can occur, (2) the fraction of the area that is active at any time, (3) the reaction rate, that is, the number of reactions per unit active area per second, and (4) the energy produced per reaction. Each of these factors, and their limits, are reviewed. A graphical means of relating these four factors over their wide variations has been devised. The instantaneous generation of atoms of new elements can also be written as the product of the first three factors and the new elemental mass produced per reaction. Again, a graphical means of presenting the factors and their results over many orders of magnitude has been developed.

  2. Kinetic and mechanistic study of the atmospheric reaction of MBO331 with Cl atoms

    NASA Astrophysics Data System (ADS)

    Rodríguez, Diana; Rodríguez, Ana; Garzón, Andrés; Granadino-Roldán, José M.; Soto, Amparo; Aranda, Alfonso; Notario, Alberto

    2012-12-01

    The present work deals with the reaction of 3-methyl-3-buten-1-ol (MBO331) with Cl atoms, which has been investigated by gas chromatography with flame ionization detection (GC-FID) at atmospheric pressure in N2 or air, using the relative rate technique. The rate constant reaction at 298 ± 1 K was found to be (5.01 ± 0.70) × 10-10 cm3 molecule-1 s-1, using cyclohexane, octane and 1-butene as a reference compounds. The temperature dependence for the reaction was studied within the 298-333 K range. Additionally, a product identification under atmospheric conditions has been performed for the first time by GC-MS, with 3-methyl-3-butenal, methacrolein and chloroacetone being observed as degradation products. A theoretical study on the reaction at the QCISD(T)/6-311G**//MP2/6-311G** level was also carried out to obtain more information on the mechanism. From the theoretical study it can be predicted that Cl addition to the double bond proceeds through lower energy barriers than H-abstraction pathways and therefore is energetically favoured. Finally, atmospheric implications of the results obtained are discussed.

  3. Acid-catalyzed reactions of hexanal on sulfuric acid particles: Identification of reaction products

    NASA Astrophysics Data System (ADS)

    Garland, Rebecca M.; Elrod, Matthew J.; Kincaid, Kristi; Beaver, Melinda R.; Jimenez, Jose L.; Tolbert, Margaret A.

    While it is well established that organics compose a large fraction of the atmospheric aerosol mass, the mechanisms through which organics are incorporated into atmospheric aerosols are not well understood. Acid-catalyzed reactions of compounds with carbonyl groups have recently been suggested as important pathways for transfer of volatile organics into acidic aerosols. In the present study, we use the aerodyne aerosol mass spectrometer (AMS) to probe the uptake of gas-phase hexanal into ammonium sulfate and sulfuric acid aerosols. While both deliquesced and dry non-acidic ammonium sulfate aerosols showed no organic uptake, the acidic aerosols took up substantial amounts of organic material when exposed to hexanal vapor. Further, we used 1H-NMR, Fourier transform infrared (FTIR) spectroscopy and GC-MS to identify the products of the acid-catalyzed reaction of hexanal in acidic aerosols. Both aldol condensation and hemiacetal products were identified, with the dominant reaction products dependent upon the initial acid concentration of the aerosol. The aldol condensation product was formed only at initial concentrations of 75-96 wt% sulfuric acid in water. The hemiacetal was produced at all sulfuric acid concentrations studied, 30-96 wt% sulfuric acid in water. Aerosols up to 88.4 wt% organic/11.1 wt% H 2SO 4/0.5 wt% water were produced via these two dimerization reaction pathways. The UV-VIS spectrum of the isolated aldol condensation product, 2-butyl 2-octenal, extends into the visible region, suggesting these reactions may impact aerosol optical properties as well as aerosol composition. In contrast to previous suggestions, no polymerization of hexanal or its products was observed at any sulfuric acid concentration studied, from 30 to 96 wt% in water.

  4. Reaction of cobalt in SO2 atmospheric at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.; Worrell, W. L.

    1983-01-01

    The reaction rate of cobalt in SO2 argon environments was measured at 650 C, 700 C, 750 C and 800 C. Product scales consist primarily of an interconnected sulfide phase in an oxide matrix. At 700 C to 800 C a thin sulfide layer adjacent to the metal is also observed. At all temperatures, the rapid diffusion of cobalt outward through the interconnected sulfide appears to be important. At 650 C, the reaction rate slows dramatically after five minutes due to a change in the distribution of these sulfides. At 700 C and 750 C the reaction is primarily diffusion controlled values of diffusivity of cobalt (CoS) calculated from this work show favorable agreement with values of diffusivity of cobalt (CoS) calculated from previous sulfidation work. At 800 C, a surface step becomes rate limiting.

  5. Reaction of cobalt in SO2 atmospheres at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.; Worrell, W. L.

    1984-01-01

    The reaction rate of cobalt in SO2 argon environments was measured at 650 C, 700 C, 750 C and 800 C. Product scales consist primarily of an interconnected sulfide phase in an oxide matrix. At 700 C to 800 C, a thin sulfide layer adjacent to the metal is also observed. At all temperatures, the rapid diffusion of cobalt outward through the interconnected sulfide appears to be important. At 650 C, the reaction rate slows dramatically after five minutes due to a change in the distribution of these sulfides. At 700 C and 750 C, the reaction is primarily diffusion controlled; values of diffusivity of cobalt (CoS) calculated from this work show favorable agreement with values of diffusivity of cobalt (CoS) calculated from previous sulfidation work. At 800 C, a surface step becomes rate limiting. Previously announced in STAR as N83-35104

  6. Atmospheric production of glycolaldehyde under hazy prebiotic conditions.

    PubMed

    Harman, Chester E; Kasting, James F; Wolf, Eric T

    2013-04-01

    The early Earth's atmosphere, with extremely low levels of molecular oxygen and an appreciable abiotic flux of methane, could have been a source of organic compounds necessary for prebiotic chemistry. Here, we investigate the formation of a key RNA precursor, glycolaldehyde (2-hydroxyacetaldehyde, or GA) using a 1-dimensional photochemical model. Maximum atmospheric production of GA occurs when the CH4:CO2 ratio is close to 0.02. The total atmospheric production rate of GA remains small, only 1 × 10(7) mol yr(-1). Somewhat greater amounts of GA production, up to 2 × 10(8) mol yr(-1), could have been provided by the formose reaction or by direct delivery from space. Even with these additional production mechanisms, open ocean GA concentrations would have remained at or below ~1 μM, much smaller than the 1-2 M concentrations required for prebiotic synthesis routes like those proposed by Powner et al. (Nature 459:239-242, 2009). Additional production or concentration mechanisms for GA, or alternative formation mechanisms for RNA, are needed, if this was indeed how life originated on the early Earth. PMID:23695543

  7. Chemical Characterization of Secondary Organic Aerosol Formed from Atmospheric Aqueous-phase Reactions of Phenolic Compounds

    NASA Astrophysics Data System (ADS)

    Yu, L.; Smith, J.; Anastasio, C.; Zhang, Q.

    2012-12-01

    Phenolic compounds, which are released in significant amounts from biomass burning, may undergo fast aqueous-phase reactions to form secondary organic aerosol (SOA) in the atmosphere. Understanding the aqueous-phase reaction mechanisms of these compounds and the composition of their reaction products is thus important for constraining SOA sources and predicting organic aerosol properties in models. In this study, we investigate the aqueous-phase reactions of three phenols (phenol, guaiacol and syringol) with two oxidants - excited triplet states (3C*) of non-phenolic aromatic carbonyls and hydroxyl radical (OH). By employing four analytical methods including high-resolution aerosol mass spectrometry, total organic carbon analysis, ion chromatography, and liquid chromatography-mass spectrometry, we thoroughly characterize the chemical compositions of the low volatility reaction products of phenols and propose formation mechanisms based on this information. Our results indicate that phenolic SOA is highly oxygenated, with O/C ratios in the range of 0.83-1.03, and that the SOA of phenol is usually more oxidized than those of guaiacol and syringol. Among the three precursors, syringol generates the largest fraction of higher molecular weight (MW) products. For the same precursor, the SOA formed via reaction with 3C* is less oxidized than that formed via reaction with OH. In addition, oxidation by 3C* enhances the formation of higher MW species, including phenolic dimers, higher oligomers and hydroxylated products, compared to reactions initiated by OH, which appear to favor the formation of organic acids. However, our results indicate that the yields of small organic acids (e.g., formate, acetate, oxalate, and malate) are low for both reaction pathways, together accounting for less than 5% of total SOA mass.

  8. Atmospheric pressure Eberlin transacetalization reactions in the heterogeneous liquid/gas phase

    NASA Astrophysics Data System (ADS)

    Augusti, Rodinei; Chen, Hao; Eberlin, Livia Schiavinato; Nefliu, Marcela; Cooks, R. Graham

    2006-07-01

    The Eberlin reaction, the ionic transacetalization of cyclic acetals and analogues with acylium and related ions, is demonstrated in the course of ion/molecule reactions at atmospheric pressure. Selected gaseous acetals (1,3-dioxolane, 2-methyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 2-phenyl-1,3-dioxolane, 1,3-dioxane, and 1,3,5-trioxane) react efficiently with the (CH3)2NCO+ acylium ion, generated by electrosonic spray ionization (ESSI) of an aqueous/methanol solution of tetramethylurea (TMU), to furnish the characteristic cyclic ionic acetals, the Eberlin products, in moderate to high yields. It is proposed that acylium ions on the surface of the ESSI-generated droplets interact with gaseous neutral reagentsE The Eberlin products dissociate exclusively to re-form the reactant (CH3)2NCO+ acylium ion upon collision-induced dissociation (CID), confirming their structures. The intact adduct, i.e., acylium ion plus neutral reagent (the stable precursor of the Eberlin product), is observed in these experiments whereas it is not observed in studies of the same Eberlin reactions under conventional reduced pressure ion/molecule reaction conditions. It is suggested that under atmospheric pressure conditions these intact adducts are likely stabilized through deactivation via collision with buffer gas.

  9. REACTION PRODUCTS FROM THE CHLORINATION OF SEAWATER

    EPA Science Inventory

    Chemical treatment of natural waters, in particular the use of chlorine as a biocide, modifies the chemistry of these waters in ways that are not fully understood. The research described in this report examined both inorganic and organic reaction products from the chlorination of...

  10. The reactions of cobalt, iron and nickel in SO2 atmospheres Similarities and differences

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.; Worrell, W. L.

    1985-01-01

    The reactions of cobalt, iron and nickel in SO2 atmospheres are reviewed and compared. A mixed oxide-sulfide product layer is observed in all cases. Cobalt and nickel exhibit similar behavior. The observed rates are near the sulfidation rates, and the reaction rate is strongly influenced by the outward diffusion of metal through an interconnected sulfide network. A continuous interconnected sulfide is not observed in the oxide-sulfide scales formed on iron, and the reaction rates are more difficult to summarize. The differences and similarities among the three metals are explained in terms of the absence of scale-gas equilibrium and the ratio of the metal diffusivity in the corresponding oxide and sulfide.

  11. The reactions of cobalt, iron and nickel in SO-2 atmospheres: Similarities and differences

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.; Worrell, W. L.

    1984-01-01

    The reactions of cobalt, iron and nickel in SO2 atmospheres are reviewed and compared. A mixed oxide-sulfide product layer is observed in all cases. Cobalt and nickel exhibits similar behavior. The observed rates are near the sulfidation rates, and the reaction rate is strongly influenced by the outward diffusion of metal through an interconnected sulfide network. A continuous interconnected sulfide is not observed in the oxide-sulfide scales formed on iron, and the reaction rates are more difficult to summarize. The differences and similarities among the three metals are explained in terms of the absence of scale-gas equilibrium and the ratio of the metal diffusivity in the corresponding oxide and sulfide.

  12. Heterogeneous Reactions of Polycyclic Aromatic Hydrocarbons on Atmospheric and Terrestrial Surfaces

    NASA Astrophysics Data System (ADS)

    Simonich, S. L.

    2014-12-01

    The heterogeneous reactions of five higher molecular weight polycyclic aromatic hydrocarbons (PAHs), benzo[a]pyrene-d12 (BaP-d12), benzo(k)fluoranthene-d12 (BkF-d12), benzo[g,h,i]perylene-d12 (BghiP-d12), dibenzo(a,i)pyrene-d14 (DBaiP-d14), and dibenzo[a,l]pyrene (DalP), with NO2, NO3/N2O5, O3, and OH radicals were investigated in a 7000 L indoor Teflon chamber. Quartz fiber filters (QFF) were used as the reaction surface and substrate and the analyses of parent PAHs and Nitro-PAH (NPAH) products was conducted using electron impact gas chromatographic mass spectrometry (GC/MS) and negative chemical ionization GC/MS. In parallel to the laboratory experiments, a theoretical study was conducted to assist in determining the formation of NPAH isomers based on the OH-radical initiated reaction. The thermodynamic stability of OH-PAH intermediates was used to indicate the position of highest electron density and the most stable NPAH products were synthesized to confirm their identity. NO2 and NO3/N2O5 were the most effective oxidizing agents in transforming PAHs deposited on filters to NPAHs, under the experimental conditions. Reaction of BaP-d12, BkF-d12 and BghiP-d12 resulted in the formation of several mono-nitro PAH isomer product, while the reaction of DalP and DaiP-d14 resulted in the formation of only one mono-nitro PAH isomer product. The direct-acting mutagenicity of the products increased the most after NO3/N2O5 exposure, particularly for BkF-d12 in which the formation of dinitro- PAHs was observed. In addition, the degradation of particulate matter (PM)-bound PAHs by heterogeneous reaction with OH radicals, O3, NO3/N2O5 was also studied. Ambient PM samples collected from Beijing, China and Riverside, California were exposed in an indoor chamber under simulated trans-Pacific atmospheric transport conditions and the formation of NPAHs was studied. NPAHs were most effectively formed during the NO3/N2O5 exposure and, for all exposures, there was no significant

  13. Atmospheric Processing Module for Mars Propellant Production

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony; Gibson, Tracy; Captain, James; Athman, Robert; Nugent, Matthew; Parks, Steven; Devor, Robert

    2013-01-01

    The multi-NASA center Mars Atmosphere and Regolith COllector/PrOcessor for Lander Operations (MARCO POLO) project was established to build and demonstrate a methane/oxygen propellant production system in a Mars analog environment. Work at the Kennedy Space Center (KSC) Applied Chemistry Laboratory is focused on the Atmospheric Processing Module (APM). The purpose of the APM is to freeze carbon dioxide from a simulated Martian atmosphere containing the minor components nitrogen, argon, carbon monoxide, and water vapor at Martian pressures (approx.8 torr) by using dual cryocoolers with alternating cycles of freezing and sublimation. The resulting pressurized CO2 is fed to a methanation subsystem where it is catalytically combined with hydrogen in a Sabatier reactor supplied by the Johnson Space Center (JSC) to make methane and water vapor. We first used a simplified once-through setup and later employed a HiCO2 recycling system to improve process efficiency. This presentation and paper will cover (1) the design and selection of major hardware items, such as the cryocoolers, pumps, tanks, chillers, and membrane separators, (2) the determination of the optimal cold head design and flow rates needed to meet the collection requirement of 88 g CO2/hr for 14 hr, (3) the testing of the CO2 freezer subsystem, and (4) the integration and testing of the two subsystems to verify the desired production rate of 31.7 g CH4/hr and 71.3 g H2O/hr along with verification of their purity. The resulting 2.22 kg of CH4/O2 propellant per 14 hr day (including O2 from electrolysis of water recovered from regolith, which also supplies the H2 for methanation) is of the scale needed for a Mars Sample Return mission. In addition, the significance of the project to NASA's new Mars exploration plans will be discussed.

  14. Atmospheric Processing Module for Mars Propellant Production

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony; Gibson, Tracy; Captain, James; Athman, Robert; Nugent, Matthew; Parks, Steven; Devor, Robert

    2013-01-01

    The multi-NASA center Mars Atmosphere and Regolith COllector/PrOcessor for Lander Operations (MARCO POLO) project was established to build and demonstrate a methane/oxygen propellant production system in a Mars analog environment. Work at the Kennedy Space Center (KSC) Applied Chemistry Laboratory is focused on the Atmospheric Processing Module (APM). The purpose of the APM is to freeze carbon dioxide from a simulated Martian atmosphere containing the minor components nitrogen, argon, carbon monoxide, and water vapor at Martian pressures (8 torr) by using dual cryocoolers with alternating cycles of freezing and sublimation. The resulting pressurized CO2 is fed to a methanation subsystem where it is catalytically combined with hydrogen in a Sabatier reactor supplied by the Johnson Space Center (JSC) to make methane and water vapor. We first used a simplified once-through setup and later employed a HiCO2 recycling system to improve process efficiency. This presentation and paper will cover (1) the design and selection of major hardware items, such as the cryocoolers, pumps, tanks, chillers, and membrane separators, (2) the determination of the optimal cold head design and flow rates needed to meet the collection requirement of 88 g CO2/hr for 14 hr, (3) the testing of the CO2 freezer subsystem, and (4) the integration and testing of the two subsystems to verify the desired production rate of 31.7 g CH4/hr and 71.3 g H20/hr along with verification of their purity. The resulting 2.22 kg of CH4/O2 propellant per 14 hr day (including O2 from electrolysis of water recovered from regolith, which also supplies the H2 for methanation) is of the scale needed for a Mars Sample Return mission. In addition, the significance of the project to NASA's new Mars exploration plans will be discussed.

  15. Atmospheric chemistry of enols: a theoretical study of the vinyl alcohol + OH + O(2) reaction mechanism.

    PubMed

    So, Sui; Wille, Uta; da Silva, Gabriel

    2014-06-17

    Enols are emerging as trace atmospheric components that may play a significant role in the formation of organic acids in the atmosphere. We have investigated the hydroxyl radical ((•)OH) initiated oxidation chemistry of the simplest enol, vinyl alcohol (ethenol, CH2═CHOH), using quantum chemical calculations and energy-grained master equation simulations. A lifetime of around 4 h was determined for vinyl alcohol in the presence of tropospheric levels of (•)OH. The reaction proceeds by (•)OH addition at both the α (66%) and β (33%) carbons of the π-system, yielding the C-centered radicals (•)CH2CH(OH)2, and HOCH2C(•)HOH, respectively. Subsequent trapping by O2 leads to the respective peroxyl radicals. About 90% of the chemically activated population of the major peroxyl radical adduct (•)O2CH2CH(OH)2 is predicted to undergo fragmentation to produce formic acid and formaldehyde, with regeneration of (•)OH. The minor peroxyl radical HOCH2C(OO(•))HOH is even less stable and undergoes almost exclusive HO2(•) elimination to form glycolaldehyde (HOCH2CHO). Formation of the latter has not been proposed before in the oxidation of vinyl alcohol. A kinetic mechanism for use in atmospheric modeling is provided, featuring phenomenological rate coefficients for formation of the three main product channels ((•)O2CH2CH(OH)2 [8%]; HC(O)OH + HCHO + (•)OH [56%]; HOCH2CHO + HO2(•) [37%]). Our study supports previous findings that vinyl alcohol should be rapidly removed from the atmosphere by reaction with (•)OH and O2 with glycolaldehyde being identified as a previously unconsidered product. Most importantly, it is shown that direct chemically activated reactions can lead to (•)OH and HO2(•) (HOx) recycling. PMID:24844308

  16. Laser driven hydrogen transfer reactions in atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Lester, Marsha I.

    2015-03-01

    Ozonolysis of alkenes, an important non-photolytic source of OH radicals in the troposphere, proceeds through energized Criegee intermediates that undergo unimolecular decay to produce OH radicals. In this work, infrared laser activation of cold methyl-substituted Criegee intermediates is utilized to drive hydrogen transfer from the methyl group to the terminal oxygen, followed by dissociation to OH radicals. State-selective excitation of the Criegee intermediates in the CH stretch overtone region combined with sensitive OH detection reveals the infrared spectra of CH3CHOO and (CH3)2 COO, effective barrier heights for the critical hydrogen transfer step, and rapid decay dynamics to OH products. Complementary theory provides insights on the infrared overtone spectra as well as vibrational excitations, structural changes, and energy required to move from the minimum energy configuration of the Criegee intermediates to the transition state for the hydrogen transfer reaction. Research supported by the National Science Foundation.

  17. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

    NASA Astrophysics Data System (ADS)

    Vaikkinen, Anu; Kauppila, Tiina J.; Kostiainen, Risto

    2016-04-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M+. decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques.

  18. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization.

    PubMed

    Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

    2016-08-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M(+.) decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques. Graphical Abstract ᅟ. PMID:27126470

  19. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

    NASA Astrophysics Data System (ADS)

    Vaikkinen, Anu; Kauppila, Tiina J.; Kostiainen, Risto

    2016-08-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M+. decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques.

  20. Atmospheric chemical reactions of monoethanolamine initiated by OH radical: mechanistic and kinetic study.

    PubMed

    Xie, Hong-Bin; Li, Chao; He, Ning; Wang, Cheng; Zhang, Shaowen; Chen, Jingwen

    2014-01-01

    Monoethanolamine (MEA) is a benchmark and widely utilized solvent in amine-based postcombustion CO2 capture (PCCC), a leading technology for reducing CO2 emission from fossil fuel power plants. The large-scale implementation of PCCC would lead to inevitable discharges of amines to the atmosphere. Therefore, understanding the kinetics and mechanisms of the transformation of representative amine MEA in the atmosphere is of great significance for risk assessment of the amine-based PCCC. In this study, the H-abstraction reaction of MEA with ·OH, and ensuing reactions of produced MEA-radicals, including isomerization, dissociation, and bimolecular reaction MEA-radicals+O2, were investigated by quantum chemical calculation [M06-2X/aug-cc-pVTZ//M06-2X/6-311++G(d,p)] and kinetic modeling. The calculated overall rate constant [(7.27 × 10(-11)) cm(3) molecule(-1) s(-1)] for H-abstraction is in excellent agreement with the experimental value [(7.02 ± 0.46) × 10(-11) cm(3) molecule(-1) s(-1)]. The results show that the product branching ratio of NH2CH2 · CHOH (MEA-β) (43%) is higher than that of NH2 · CHCH2OH (MEA-α) (39%), clarifying that MEA-α is not an exclusive product. On the basis of the unveiled reaction mechanisms of MEA-radicals + O2, the proton transfer reaction mass spectrometry signal (m/z 60.044), not recognized in the experiment, was identified. PMID:24438015

  1. Atmospheric Processing Module for Mars Propellant Production

    NASA Technical Reports Server (NTRS)

    Muscatello, Anthony C.

    2014-01-01

    The multi-NASA center Mars Atmosphere and Regolith COllectorPrOcessor for Lander Operations (MARCO POLO) project was established to build and demonstrate a methaneoxygen propellant production system in a Mars analog environment. Work at the Kennedy Space Center (KSC) Applied Chemistry Laboratory is focused on the Atmospheric Processing Module (APM). The purpose of the APM is to freeze carbon dioxide from a simulated Martian atmosphere containing the minor components nitrogen, argon, carbon monoxide, and water vapor at Martian pressures (8 torr) by using dual cryocoolers with alternating cycles of freezing and sublimation. The resulting pressurized CO(sub 2) is fed to a methanation subsystem where it is catalytically combined with hydrogen in a Sabatier reactor supplied by the Johnson Space Center (JSC) to make methane and water vapor. We first used a simplified once-through setup and later employed a H(sub 2)CO(sub 2) recycling system to improve process efficiency. This presentation and paper will cover (1) the design and selection of major hardware items, such as the cryocoolers, pumps, tanks, chillers, and membrane separators, (2) the determination of the optimal cold head design and flow rates needed to meet the collection requirement of 88 g CO(sub 2) hr for 14 hr, (3) the testing of the CO(sub 2) freezer subsystem, and (4) the integration and testing of the two subsystems to verify the desired production rate of 31.7 g CH(sub 4) hr and 71.3 g H(sub 2)O hr along with verification of their purity. The resulting 2.22 kg of CH(sub 2)O(sub 2) propellant per 14 hr day (including O(sub 2) from electrolysis of water recovered from regolith, which also supplies the H(sub 2) for methanation) is of the scale needed for a Mars Sample Return mission. In addition, the significance of the project to NASAs new Mars exploration plans will be discussed.

  2. Atmospheric Processing Module for Mars Propellant Production

    NASA Technical Reports Server (NTRS)

    Muscatello, A.; Devor, R.; Captain, J.

    2014-01-01

    The multi-NASA center Mars Atmosphere and Regolith COllector/PrOcessor for Lander Operations (MARCO POLO) project was established to build and demonstrate a methaneoxygen propellant production system in a Mars analog environment. Work at the Kennedy Space Center (KSC) Applied Chemistry Laboratory is focused on the Atmospheric Processing Module (APM). The purpose of the APM is to freeze carbon dioxide from a simulated Martian atmosphere containing the minor components nitrogen, argon, carbon monoxide, and water vapor at Martian pressures (approx. 8 torr) by using dual cryocoolers with alternating cycles of freezing and sublimation. The resulting pressurized CO(sub 2) is fed to a methanation subsystem where it is catalytically combined with hydrogen in a Sabatier reactor supplied by the Johnson Space Center (JSC) to make methane and water vapor. We first used a simplified once-through setup and later employed a H(sub 2)CO(sub 2) recycling system to improve process efficiency. This presentation and paper will cover (1) the design and selection of major hardware items, such as the cryocoolers, pumps, tanks, chillers, and membrane separators, (2) the determination of the optimal cold head design and flow rates needed to meet the collection requirement of 88 g CO(sub 2) hr for 14 hr, (3) the testing of the CO(sub 2) freezer subsystem, and (4) the integration and testing of the two subsystems to verify the desired production rate of 31.7 g CH(sub 4) hr and 71.3 g H(sub 2)O hr along with verification of their purity. The resulting 2.22 kg of CH(sub 2)O(sub 2) propellant per 14 hr day (including O(sub 2) from electrolysis of water recovered from regolith, which also supplies the H(sub 2) for methanation) is of the scale needed for a Mars Sample Return mission. In addition, the significance of the project to NASAs new Mars exploration plans will be discussed.

  3. Aqueous Phase Photo-Oxidation of Succinic Acid: Changes in Hygroscopic Properties and Reaction Products

    NASA Astrophysics Data System (ADS)

    Hudson, P. K.; Ninokawa, A.; Hofstra, J.; de Lijser, P.

    2013-12-01

    Atmospheric aerosol particles have been identified as important factors in understanding climate change. The extent to which aerosols affect climate is determined, in part, by hygroscopic properties which can change as a result of atmospheric processing. Dicarboxylic acids, components of atmospheric aerosol, have a wide range of hygroscopic properties and can undergo oxidation and photolysis reactions in the atmosphere. In this study, the hygroscopic properties of succinic acid aerosol, a non-hygroscopic four carbon dicarboxylic acid, were measured with a humidified tandem differential mobility analyzer (HTDMA) and compared to reaction products resulting from the aqueous phase photo-oxidation reaction of hydrogen peroxide and succinic acid. Reaction products were determined and quantified using gas chromatography-flame ionization detection (GC-FID) and GC-mass spectrometry (GC-MS) as a function of hydrogen peroxide:succinic acid concentration ratio and photolysis time. Although reaction products include larger non-hygroscopic dicarboxylic acids (e.g. adipic acid) and smaller hygroscopic dicarboxylic acids (e.g. malonic and oxalic acids), comparison of hygroscopic growth curves to Zdanovskii-Stokes-Robinson (ZSR) predictions suggests that the hygroscopic properties of many of the product mixtures are largely independent of the hygroscopicity of the individual components. This study provides a framework for future investigations to fully understand and predict the role of chemical reactions in altering atmospheric conditions that affect climate.

  4. Assessment of reaction-rate predictions of a collision-energy approach for chemical reactions in atmospheric flows.

    SciTech Connect

    Gallis, Michail A.; Bond, Ryan Bomar; Torczynski, John Robert

    2010-06-01

    A recently proposed approach for the Direct Simulation Monte Carlo (DSMC) method to calculate chemical-reaction rates is assessed for high-temperature atmospheric species. The new DSMC model reproduces measured equilibrium reaction rates without using any macroscopic reaction-rate information. Since it uses only molecular properties, the new model is inherently able to predict reaction rates for arbitrary non-equilibrium conditions. DSMC non-equilibrium reaction rates are compared to Park's phenomenological nonequilibrium reaction-rate model, the predominant model for hypersonic-flow-field calculations. For near-equilibrium conditions, Park's model is in good agreement with the DSMC-calculated reaction rates. For far-from-equilibrium conditions, corresponding to a typical shock layer, significant differences can be found. The DSMC predictions are also found to be in very good agreement with measured and calculated non-equilibrium reaction rates, offering strong evidence that this is a viable and reliable technique to predict chemical reaction rates.

  5. Reactions of volatile organic compounds in the atmosphere: Ozone-alkene reactions

    NASA Astrophysics Data System (ADS)

    Fenske, Jill Denise

    2000-08-01

    Photochemical smog cannot form without sunlight, nitrogen oxides, and volatile organic compounds (VOC). This dissertation addresses several different aspects of VOC chemistry in the atmosphere. Aside from ambient levels of VOC outdoors, VOC are also present at moderate concentrations indoors. Many studies have measured indoor air concentrations of VOC, but only one considered the effects of human breath. The major VOC in the breath of healthy individuals are isoprene (12-580 ppb), acetone (1.2-1800 ppb), ethanol (13-1000 ppb), methanol (160-2000 ppb), and other alcohols. Human emissions of VOC are negligible on a regional (less than 4%) and global scale (less than 0.3%). However, in indoor air, under fairly crowded situations, human emissions of VOC may dominate other sources of VOC. An important class of VOC in the atmosphere is alkenes, due to their high reactivity. The ozone reaction with alkenes forms OH radicals, a powerful oxidizing agent in the troposphere. OH radical formation yields from the ozonolysis of several cycloalkenes were measured using small amounts of fast-reacting aromatics and aliphatic ethers to trace OH formation. The values are 0.62 +/- 0.15, 0.54 +/- 0.13, 0.36 +/- 0.08, and 0.91 +/- 0.20 for cyclopentene, cyclohexene, cycloheptene and 1-methylcyclohexene, respectively. Density functional theory calculations at the B3LYP/6-31 G(d,p) level are presented to aid in understanding the trends observed. The pressure dependence of OH radical yields may lend insight into the formation mechanism. We have made the first study of the pressure dependence of the OH radical yield for ethene, propene, 1-butene, trans-2-butene, and 2,3-dimethyl-2- butene over the range 20-760 Torr, and trans -3-hexene, and cyclopentene over the range 200-760 Torr. The OH yields from ozonolysis of ethene and propene were pressure dependent, while the other compounds had OH yields that were independent of pressure. Ozone-alkene reactions form vibrationally excited carbonyl

  6. Accurate measurements of OH reaction rate constants over atmospheric temperatures and the atmospheric lifetime of trace gases

    NASA Astrophysics Data System (ADS)

    Orkin, V. L.; Khamaganov, V. G.; Martynova, L. E.; Kurylo, M. J.

    2013-12-01

    Reactions with hydroxyl radicals and photolysis are the main processes dictating the compound residence time in the atmosphere for a majority of trace gases. In case of very short lived compounds their reaction with OH dictates both the atmospheric lifetime and active halogen release. Therefore, the accuracy of OH kinetic data is of primary importance for the purpose of comprehensive atmospheric modeling of compound's impact on the atmosphere, such as in ozone depletion (ODP) and climate change (GWP). The currently recommended uncertainties of OH reaction rate constants (NASA/JPL Publications and IUPAC Publications) exceed 10% at room temperature for the majority of compounds to be larger at lower temperatures of atmospheric interest. Thus, uncertainties in the photochemical properties of potential and current atmospheric trace gases obtained under controlled laboratory conditions may constitute a major source of uncertainty in estimating the compound's environmental impact. We will present the higher accuracy results of OH reaction rate constant determinations between 220 K and 370 K. A statistical analysis of the data will be discussed. The high precision of kinetic measurements performed at low temperatures allows reliable determination of temperature dependences of the rate constants. This is especially important because we found that many OH reactions exhibit the curvature of the Arrhenius plots. A detailed inventory of sources of instrumental uncertainties related to our experiment proves a total uncertainty of the OH reaction rate constant to be as small as ~2-3%. The estimation of the atmospheric lifetime of a compound based on its OH reaction rate constant will be discussed.

  7. Reactions of Atmospheric Particulate Stabilized Criegee Intermediates Lead to High-Molecular-Weight Aerosol Components.

    PubMed

    Wang, MingYi; Yao, Lei; Zheng, Jun; Wang, XinKe; Chen, JianMin; Yang, Xin; Worsnop, Douglas R; Donahue, Neil M; Wang, Lin

    2016-06-01

    Aging of organic aerosol particles is one of the most poorly understood topics in atmospheric aerosol research. Here, we used an aerosol flow tube together with an iodide-adduct high-resolution time-of-flight chemical-ionization mass spectrometer equipped with a Filter Inlet for Gases and AEROsols (FIGAERO-HRToF-CIMS) to investigate heterogeneous ozonolysis of oleic acid (OL), developing a comprehensive oxidation mechanism with observed products. In addition to the well-known first-generation C9 products including nonanal, nonanoic acid, azelaic acid, and 9-oxononanoic acid, the iodide-adduct chemical ionization permitted unambiguous determination of a large number of high-molecular-weight particulate products up to 670 Da with minimum amounts of fragmentation. These high-molecular-weight products are characterized by a fairly uniform carbon oxidation state but stepwise addition of a carbon backbone moiety, and hence continuous decrease in the volatility. Our results demonstrate that heterogeneous oxidation of organic aerosols has a significant effect on the physiochemical properties of organic aerosols and that reactions of particulate SCIs from ozonolysis of an unsaturated particulate species represent a previously underappreciated mechanism that lead to formation of high-molecular-weight particulate products that are stable under typical atmospheric conditions. PMID:27186797

  8. Ion transport of Fr nuclear reaction products

    SciTech Connect

    Behr, J.A.; Cahn, S.B.; Dutta, S.B.

    1993-04-01

    Experiments planned for fundamental studies of radioactive atoms in magneto-optic traps require efficient deceleration and transport of nuclear reaction products to energies and locations where they can be trapped. The authors have built a low-energy ion transport system for Francium and other alkalis. A thick Au target is held on a W rod at 45{degrees} to the accelerator beam direction. The heavy-ion fusion reaction 115 MeV {sup 18}O + {sup 197}Au produces {sup 211,210,209}Fr recoil products which are stopped in the target. The target is heated to close to the melting point of Au to allow the Fr to diffuse to the surface, where it is ionized due to Au`s high work function, and is directly extracted by an electrode at 90{degrees} to the accelerator beam direction. The Fr is transported by electrostatic optics {approximately}1 m to a catcher viewed by an {alpha} detector: {ge}15% of the Fr produced in the target reaches the catcher. 2{times}10{sup 5} Fr/sec have been produced at the catcher, yielding at equilibrium a sample of 3x10{sup 7}Fr nuclei. This scheme physically decouples the target diffusion from the surface neutralization process, which can occur at a lower temperature more compatible with the neutral-atom trap.

  9. Transfer-type products accompanying cold fusion reactions

    SciTech Connect

    Adamian, G.G.; Antonenko, N.V.

    2005-12-15

    Production of nuclei heavier than the target is treated for projectile-target combinations used in cold fusion reactions leading to superheavy nuclei. These products are related to transfer-type or to asymmetry-exit-channel quasifission reactions. The production of isotopes in the transfer-type reactions emitting of {alpha} particles with large energies is discussed.

  10. Feasibility Study of Venus Surface Cooling Using Chemical Reactions with the Atmosphere

    NASA Technical Reports Server (NTRS)

    Evans, Christopher

    2013-01-01

    A literature search and theoretical analysis were conducted to investigate the feasibility of cooling a craft on Venus through chemical reformation of materials from the atmosphere. The core concept was to take carbon dioxide (CO2) from the Venus atmosphere and chemically reform it into simpler compounds such as carbon, oxygen, and carbon monoxide. This process is endothermic, taking energy from the surroundings to produce a cooling effect. A literature search was performed to document possible routes for achieving the desired reactions. Analyses indicated that on Venus, this concept could theoretically be used to produce cooling, but would not perform as well as a conventional heat pump. For environments other than Venus, the low theoretical performance limits general applicability of this concept, however this approach to cooling may be useful in niche applications. Analysis indicated that environments with particular atmospheric compositions and temperatures could allow a similar cooling system to operate with very good performance. This approach to cooling may also be useful where the products of reaction are also desirable, or for missions where design simplicity is valued. Conceptual designs for Venus cooling systems were developed using a modified concept, in which an expendable reactant supply would be used to promote more energetically favorable reactions with the ambient CO2, providing cooling for a more limited duration. This approach does not have the same performance issues, but the use of expendable supplies increases the mass requirements and limits the operating lifetime. This paper summarizes the findings of the literature search and corresponding analyses of the various cooling options.

  11. Feasibility Study of Venus Surfuce Cooling Using Chemical Reactions with the Atmosphere

    NASA Technical Reports Server (NTRS)

    Evans, Christopher

    2013-01-01

    A literature search and theoretical analysis were conducted to investigate the feasibility of cooling a craft on Venus through chemical reformation of materials from the atmosphere. The core concept was to take carbon dioxide (CO2) from the Venus atmosphere and chemically reform it into simpler compounds such as carbon, oxygen, and carbon monoxide. This process is endothermic, taking energy from the surroundings to produce a cooling effect. A literature search was performed to document possible routes for achieving the desired reactions. Analyses indicated that on Venus, this concept could theoretically be used to produce cooling, but would not perform as well as a conventional heat pump. For environments other than Venus, the low theoretical performance limits general applicability of this concept, however this approach to cooling may be useful in niche applications. Analysis indicated that environments with particular atmospheric compositions and temperatures could allow a similar cooling system to operate with very good performance. This approach to cooling may also be useful where the products of reaction are also desirable, or for missions where design simplicity is valued. Conceptual designs for Venus cooling systems were developed using a modified concept, in which an expendable reactant supply would be used to promote more energetically favorable reactions with the ambient CO2, providing cooling for a more limited duration. This approach does not have the same performance issues, but the use of expendable supplies increases the mass requirements and limits the operating lifetime. This paper summarizes the findings of the literature search and corresponding analyses of the various cooling options

  12. ENVIRONMENTAL CHAMBER STUDIES OF MERCURY REACTIONS IN THE ATMOSPHERE

    EPA Science Inventory

    Mercury is released into the environment through both natural and anthropogenic pathways. The cycling and fate of mercury in atmospheric, soil, and water ecosystems is impacted by various factors, including chemical transformation and transport. An understanding of these proces...

  13. Measuring OH Reaction Rate Constants and Estimating the Atmospheric Lifetimes of Trace Gases.

    NASA Astrophysics Data System (ADS)

    Orkin, Vladimir; Kurylo, Michael

    2015-04-01

    Reactions with hydroxyl radicals and photolysis are the main processes dictating a compound's residence time in the atmosphere for a majority of trace gases. In case of very short-lived halocarbons their reaction with OH dictates both the atmospheric lifetime and active halogen release. Therefore, the accuracy of OH kinetic data is of primary importance for the comprehensive modeling of a compound's impact on the atmosphere, such as in ozone depletion (i.e., the Ozone Depletion Potential, ODP) and climate change (i.e., the Global Warming Potential, GWP), each of which are dependent on the atmospheric lifetime of the compound. We have demonstrated the ability to conduct very high accuracy determinations of OH reaction rate constants over the temperature range of atmospheric interest, thereby decreasing the uncertainty of kinetic data to 2-3%. The atmospheric lifetime of a well-mixed compound due to its reaction with tropospheric hydroxyl radicals can be estimated by using a simple scaling procedure that is based on the results of field observations of methyl chloroform concentrations and detailed modeling of the OH distribution in the atmosphere. The currently available modeling results of the atmospheric fate of various trace gases allow for an improved understanding of the ability and accuracy of simplified semi-empirical estimations of atmospheric lifetimes. These aspects will be illustrated in this presentation for a variety of atmospheric trace gases.

  14. Measuring OH Reaction Rate Constants and Estimating the Atmospheric Lifetimes of Trace Gases.

    NASA Astrophysics Data System (ADS)

    Orkin, V. L.; Kurylo, M. J., III

    2014-12-01

    Reactions with hydroxyl radicals and photolysis are the main processes dictating a compound's residence time in the atmosphere for a majority of trace gases. In case of very short-lived halocarbons their reaction with OH dictates both the atmospheric lifetime and active halogen release. Therefore, the accuracy of OH kinetic data is of primary importance for the comprehensive modeling of a compound's impact on the atmosphere, such as in ozone depletion (i.e., the Ozone Depletion Potential, ODP) and climate change (i.e., the Global Warming Potential, GWP), each of which are dependent on the atmospheric lifetime of the compound. We have demonstrated the ability to conduct very high accuracy determinations of OH reaction rate constants over the temperature range of atmospheric interest, thereby decreasing the uncertainty of kinetic data to 2-3%. The atmospheric lifetime of a tropospherically well-mixed compound due to its reaction with tropospheric hydroxyl radicals can be estimated by using a simple scaling procedure that is based on the results of field observations of methyl chloroform concentrations and detailed modeling of the OH distribution in the atmosphere. The currently available modeling results of the atmospheric fate of various trace gases allow for an improved understanding of the ability and accuracy of simplified semi-empirical estimations of atmospheric lifetimes. These aspects will be illustrated in this presentation for a variety of atmospheric trace gases.

  15. Production of pesticide metabolites by oxidative reactions.

    PubMed

    Hodgson, E

    1982-08-01

    The cytochrome P-450-dependent monooxygenase system catalyzes a wide variety of oxidations of pesticide chemicals and related compounds. These reactions include epoxidation and aromatic hydroxylation, aliphatic hydroxylation, O-, N- and S-dealkylation, N-oxidation, oxidative deamination, S-oxidation, P-oxidation, desulfuration and ester cleavage and may result in either detoxication or activation of the pesticide. The current status of such reactions, relative to the production, in vivo, of biologically active intermediates in pesticide metabolism is summarized. More recently we have shown that the FAD-containing monooxygenase of mammalian liver (E.C.1.14.13.8), a xenobiotic metabolizing enzyme of broad specificity formerly known as an amine oxidase, is involved in a variety of pesticide oxidations. These include sulfoxidation of organophosphorus insecticides such as phorate and disulfoton, oxidative desulfuration of phosphonate insecticides such as fonofos and oxidation at the phosphorus atom in such compounds as the cotton defoliant, folex. The relative importance of the FAD-containing monooxygenase vis-a-vis the cytochrome P-450-dependent monooxygenase system is discussed, based on in vitro studies on purified enzymes. PMID:7161848

  16. Assessment and Requirements of Nuclear Reaction Databases for GCR Transport in the Atmosphere and Structures

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Wilson, J. W.; Shinn, J. L.; Tripathi, R. K.

    1998-01-01

    The transport properties of galactic cosmic rays (GCR) in the atmosphere, material structures, and human body (self-shielding) am of interest in risk assessment for supersonic and subsonic aircraft and for space travel in low-Earth orbit and on interplanetary missions. Nuclear reactions, such as knockout and fragmentation, present large modifications of particle type and energies of the galactic cosmic rays in penetrating materials. We make an assessment of the current nuclear reaction models and improvements in these model for developing required transport code data bases. A new fragmentation data base (QMSFRG) based on microscopic models is compared to the NUCFRG2 model and implications for shield assessment made using the HZETRN radiation transport code. For deep penetration problems, the build-up of light particles, such as nucleons, light clusters and mesons from nuclear reactions in conjunction with the absorption of the heavy ions, leads to the dominance of the charge Z = 0, 1, and 2 hadrons in the exposures at large penetration depths. Light particles are produced through nuclear or cluster knockout and in evaporation events with characteristically distinct spectra which play unique roles in the build-up of secondary radiation's in shielding. We describe models of light particle production in nucleon and heavy ion induced reactions and make an assessment of the importance of light particle multiplicity and spectral parameters in these exposures.

  17. First steps towards the reaction kinetics of HMDSO in an atmospheric pressure plasma jet in argon

    NASA Astrophysics Data System (ADS)

    Loffhagen, Detlef; Becker, Markus M.; Foest, Rüdiger; Schäfer, Jan; Sigeneger, Florian

    2014-10-01

    Hexamethyldisiloxane (HMDSO) is a silicon-organic compound which is often used as precursor for thin-film deposition by means of plasma polymerization because of its high deposition rate and low toxicity. To improve the physical understanding of the deposition processes, fundamental investigations have been performed to clarify the plasma-chemical reaction pathways of HMDSO and their effect on the composition and structure of the deposited film. The current contribution represents the main primary and secondary plasma-chemical processes and their reaction products in the effluent region of an argon plasma jet at atmospheric pressure. The importance of the different collision processes of electrons and heavy particles are discussed. Results of numerical modelling of the plasma jet and the Ar-HMDSO reaction kinetics indicate that the fragmentation of HMDSO is mainly initiated by collisions with molecular argon ions, while Penning ionization processes play a minor role for the reaction kinetics in the effluent region of the jet. The work has been supported by the German Research Foundation (DFG) under Grant LO 623/3-1.

  18. Reactions of uranium hexafluoride photolysis products

    NASA Astrophysics Data System (ADS)

    Lyman, John L.; Laguna, Glenn; Greiner, N. R.

    1985-01-01

    This paper confirms that the ultraviolet photolysis reactions of UF6 in the B band spectral region is simple bond cleavage to UF5 and F. The photolysis products may either recombine to UF6 or the UF5 may dimerize, and ultimately polymerize, to solid UF5 particles. We use four methods to set an upper limit for the rate constant for recombination of kr<2.0×10-12cm3 molecule-1 s-1. We measure the rate constant for UF5 dimerization to be kd=(1.0±0.2)×10-11 cm3 molecule-1 s-1. The principal method employed in these studies is the use of diode lasers to monitor, in real time, the changes in density of the species UF6 and UF5 after laser photolysis of the UF6 gas sample.

  19. Electroweak meson production reaction in the nucleon resonance region

    SciTech Connect

    Sato, Toru

    2015-10-15

    We report on our recent study of the the neutrino-nucleon reaction in the nucleon resonance region. The dynamical reaction model of meson production reaction on the nucleon for the pion and photon induced reaction has been developed in order to investigate the spectrum of nucleon excited state. We have extended this model in order to describe the weak meson production reactions with the πN, ηN, KΛ, KΣ and ππN final states. We also studied the role of the final state interaction in the photon and the neutrino induced pion production reaction on the deuteron around the Δ(1232) resonance region.

  20. Atmospheric chemistry of hydrogen halides: Reactions on ice and in strong acids

    SciTech Connect

    Ravishankara, A.R.

    1995-12-31

    Reactions of hydrogen halides, HCl, HBr, and HI, in sulfuric acid droplets, ice, and liquid water play important roles in the chemistry of Earth`s atmosphere. The hydrogen halides react with other species such as HOCl, ClONO{sub 2}, BrONO{sub 2}, and HOBr to liberate active halogens, the form that can destroy ozone. The impact of these reactions on the chemistry of the ozone in the atmosphere will be described. Also, a brief discussion of the mechanisms of these reactions will be given. Possible experimental and theoretical investigations that can shed light on these reactions will be pointed out.

  1. Kinetics of Thermochemical Reactions Important in the Venus Atmospheric Sulfur Cycle

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr.

    1997-01-01

    The purpose of this project was to experimentally measure the rates of several thermochemical gas-solid reactions between sulfur gases in the Venus atmosphere and reactive minerals on the hot Venus surface. Despite the great importance of these reactions for the maintenance of significant amounts of sulfur gases (and thus for the maintenance of the global cloud cover) in the atmosphere of Venus, essentially no kinetic data are currently available for them.

  2. Nitrogen-Containing Low Volatile Compounds from Pinonaldehyde-Dimethylamine Reaction in the Atmosphere: A Laboratory and Field Study.

    PubMed

    Duporté, Geoffroy; Parshintsev, Jevgeni; Barreira, Luís M F; Hartonen, Kari; Kulmala, Markku; Riekkola, Marja-Liisa

    2016-05-01

    Pinonaldehyde, which is among the most abundant oxidation products of α-pinene, and dimethylamine were selected to study the formation of N-containing low volatile compounds from aldehyde-amine reactions in the atmosphere. Gas phase reactions took place in a Tedlar bag, which was connected to a mass spectrometer ionization source via a short deactivated fused silica column. In addition to on-line analysis, abundance of gaseous precursors and reaction products were monitored off-line. Condensable products were extracted from the bag's walls with a suitable solvent and analyzed by gas chromatography coupled to chemical ionization high-resolution quadrupole time-of-flight mass spectrometry and by ultra-high-performance liquid chromatography coupled to electrospray ionization Orbitrap mass spectrometry. The reactions carried out resulted in several mid-low vapor pressure nitrogen-containing compounds that are potentially important for the formation of secondary organic aerosols in the atmosphere. Further, the presence of brown carbon, confirmed by liquid chromatography-UV-vis-mass spectrometry, was observed. Some of the compounds identified in the laboratory study were also observed in aerosol samples collected at SMEAR II station (Hyytiälä, Finland) in August 2015 suggesting the importance of aldehyde-amine reactions for the aerosol formation and growth. PMID:27035788

  3. Kinetics of OH + CO reaction under atmospheric conditions

    NASA Technical Reports Server (NTRS)

    Hynes, A. J.; Wine, P. H.; Ravishankara, A. R.

    1986-01-01

    A pulsed laser photolysis-pulsed laser-induced fluorescence technique is used to directly measure the temperature, pressure, and H2O concentration dependence on k1 in air. K1 is found to increase linearly with increasing pressure at pressures of not greater than 1 atm, and the pressure dependence of k1 at 299 K is the same in N2 buffer gas as in O2 buffer gas. The rate constant in the low-pressure limit and the slope of the k1 versus pressure dependence are shown to be the same at 262 K as at 299 K. The present results significantly reduce the current atmospheric model uncertainties in the temperature dependence under atmospheric conditions, in the third body efficiency of O2, and in the effect of water vapor on k1.

  4. Photochemical production of formaldehyde in earth's primitive atmosphere

    NASA Technical Reports Server (NTRS)

    Pinto, J. P.; Gladstone, G. R.; Yung, Y. L.

    1980-01-01

    Formaldehyde could have been produced by photochemical reactions in the earth's primitive atmosphere, at a time when it consisted mainly of molecular nitrogen, water vapor, carbon dioxide, and trace amounts of molecular hydrogen and carbon monoxide. Removal of formaldehyde from the atmosphere by precipitation can provide a source of organic carbon to the oceans at the rate of 100 billion moles per year. Subsequent reactions of formaldehyde in primeval aquatic environments would have implications for the abiotic synthesis of complex organic molecules and the origin of life.

  5. Photochemical production of formaldehyde in earth's primitive atmosphere

    NASA Astrophysics Data System (ADS)

    Pinto, J. P.; Gladstone, G. R.; Yung, Y. L.

    1980-10-01

    Formaldehyde could have been produced by photochemical reactions in the earth's primitive atmosphere, at a time when it consisted mainly of molecular nitrogen, water vapor, carbon dioxide, and trace amounts of molecular hydrogen and carbon monoxide. Removal of formaldehyde from the atmosphere by precipitation can provide a source of organic carbon to the oceans at the rate of 100 billion moles per year. Subsequent reactions of formaldehyde in primeval aquatic environments would have implications for the abiotic synthesis of complex organic molecules and the origin of life.

  6. Energy distribution among reaction products. V.

    NASA Technical Reports Server (NTRS)

    Anlauf, K. G.; Horne, D. S.; Macdonald, R. G.; Polanyi, J. C.; Woodall, K. B.

    1972-01-01

    Discussion of three reactions, one point of theoretical interest being the predicted correlation between barrier height and barrier location. The H + Br 2 reaction having a lower activation barrier than H + Cl 2, should have an earlier barrier, and hence a greater percentage attractive energy release and higher efficiency of vibrational excitation. Information is developed concerning the effect of isotopic substitution in the pair of reactions H + Cl 2 and D + Cl 2. The 'arrested relaxation' method was used. Essentially, the method involves reacting two diffuse reagent beams in a reaction vessel with background pressure less than 0.001 torr, and with walls cooled by liquid nitrogen or liquid helium.

  7. Molecule-based approach for computing chemical-reaction rates in upper atmosphere hypersonic flows.

    SciTech Connect

    Gallis, Michail A.; Bond, Ryan Bomar; Torczynski, John Robert

    2009-08-01

    This report summarizes the work completed during FY2009 for the LDRD project 09-1332 'Molecule-Based Approach for Computing Chemical-Reaction Rates in Upper-Atmosphere Hypersonic Flows'. The goal of this project was to apply a recently proposed approach for the Direct Simulation Monte Carlo (DSMC) method to calculate chemical-reaction rates for high-temperature atmospheric species. The new DSMC model reproduces measured equilibrium reaction rates without using any macroscopic reaction-rate information. Since it uses only molecular properties, the new model is inherently able to predict reaction rates for arbitrary nonequilibrium conditions. DSMC non-equilibrium reaction rates are compared to Park's phenomenological non-equilibrium reaction-rate model, the predominant model for hypersonic-flow-field calculations. For near-equilibrium conditions, Park's model is in good agreement with the DSMC-calculated reaction rates. For far-from-equilibrium conditions, corresponding to a typical shock layer, the difference between the two models can exceed 10 orders of magnitude. The DSMC predictions are also found to be in very good agreement with measured and calculated non-equilibrium reaction rates. Extensions of the model to reactions typically found in combustion flows and ionizing reactions are also found to be in very good agreement with available measurements, offering strong evidence that this is a viable and reliable technique to predict chemical reaction rates.

  8. THE OZONE REACTION WITH BUTADIENE: FORMATION OF TOXIC PRODUCTS. (R826236)

    EPA Science Inventory

    Abstract

    The formation yields of acrolein, 1,2-epoxy-3-butene and OH radicals have been measured from reaction of ozone with 1,3-butadiene at room temperature and atmosphere pressure. 1,3,5-Trimethyl benzene was added to scavenge OH radicals in measurements of product ...

  9. Middle atmosphere heating by exothermic chemical reactions involving odd-hydrogen species

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.; Solomon, Susan

    1991-01-01

    The rate of heating which occurs in the middle atmosphere due to four exothermic reactions involving members of the odd-hydrogen family is calculated. The following reactions are considered: O + OH yields O2 + H; H + O2 + M yields HO2 + M; H + O3 yields OH + O2; and O + HO2 yields OH + O2. It is shown that the heating rates due to these reactions rival the oxygen-related heating rates conventionally considered in middle-atmosphere models. The conversion of chemical potential energy into molecular translational energy (heat) by these odd-hydrogen reactions is shown to be a significant energy source in the middle atmosphere that has not been previously considered.

  10. Elusive anion growth in Titan's atmosphere: Low temperature kinetics of the C3N- + HC3N reaction

    NASA Astrophysics Data System (ADS)

    Bourgalais, Jérémy; Jamal-Eddine, Nour; Joalland, Baptiste; Capron, Michael; Balaganesh, Muthiah; Guillemin, Jean-Claude; Le Picard, Sébastien D.; Faure, Alexandre; Carles, Sophie; Biennier, Ludovic

    2016-06-01

    Ion chemistry appears to be deeply involved in the formation of heavy molecules in the upper atmosphere of Titan. These large species form the seeds of the organic aerosols responsible for the opaque haze surrounding the biggest satellite of Saturn. The chemical pathways involving individual anions remain however mostly unknown. The determination of the rates of the elementary reactions with ions and the identification of the products are essential to the progress in our understanding of Titan's upper atmosphere. We have taken steps in that direction through the investigation of the low temperature reactivity of C3N- , which was tentatively identified in the spectra measured by the CAPS-ELS instrument of the Cassini spacecraft during its high altitude flybys. The reaction of this anion with HC3N, one of the most abundant trace organics in the atmosphere, has been studied over the 49-294 K temperature range in uniform supersonic flows using the CRESU technique. The proton transfer is found to be the main exit channel (>91%) of the C315N- + HC3N reaction. It remains however indistinguishable with the non-isotopically labeled C314N- reactant. The T - 1 / 2 temperature dependence of this proton transfer reaction and its global rate are reasonably well reproduced theoretically using an average dipole orientation model. A minor exit channel, reactive detachment (< 9%), has also been uncovered, although the nature of the neutral products has not been determined. It is concluded that the C314N- + HC3N reaction cannot contribute to the growth of molecular anions in the upper atmosphere of Titan. Due to the low branching into the neutral exit channel, it cannot contribute either to the growth of neutrals even assuming a complete mass transfer.

  11. The production of trace gases by photochemistry and lightning in the early atmosphere

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Tennille, G. M.; Towe, K. M.; Khanna, R. K.

    1986-01-01

    Recent atmospheric calculation suggest that the prebiological atmosphere was most probably composed of nitrogen, carbon dioxide, and water vapor, resulting from volatile outgassing, as opposed to the older view of a strongly reducing early atmosphere composed of methane, ammonia, and hydrogen. Photochemical calculations indicate that methane would have been readily destroyed via reaction with the hydroxyl radical produced from water vapor and that ammonia would have been readily lost via photolysis and rainout. The rapid loss of methane and ammonia, coupled with the absence of a significant source of these gases, suggest that atmospheric methane and ammonia were very short lived, if they were present at all. An early atmosphere of N2, CO2, and H2O is stable and leads to the chemical production of a number of atmospheric species of biological significance, including oxygen, ozone, carbon monoxide, formaldehyde, and hydrogen cyanide. Using a photochemical model of the early atmosphere, the chemical productionof these species over a wide range of atmospheric parameters were investigated. These calculations indicate that early atmospheric levels of O3 were significantly below the levels needed to provide UV shielding. The fate of volcanically emitted sulfur species, e.g., sulfur dioxide and hydrogen sulfide, was investigated in the early atmosphere to assess their UV shielding properties. The photochemical calculations show that these species were of insufficient levels, due in part to their short photochemical lifetimes, to provide UV shielding.

  12. Reactions of Azine Anions with Nitrogen and Oxygen Atoms: Implications for Titan's Upper Atmosphere and Interstellar Chemistry.

    PubMed

    Wang, Zhe-Chen; Cole, Callie A; Demarais, Nicholas J; Snow, Theodore P; Bierbaum, Veronica M

    2015-08-26

    Azines are important in many extraterrestrial environments, from the atmosphere of Titan to the interstellar medium. They have been implicated as possible carriers of the diffuse interstellar bands in astronomy, indicating their persistence in interstellar space. Most importantly, they constitute the basic building blocks of DNA and RNA, so their chemical reactivity in these environments has significant astrobiological implications. In addition, N and O atoms are widely observed in the ISM and in the ionospheres of planets and moons. However, the chemical reactions of molecular anions with abundant interstellar and atmospheric atomic species are largely unexplored. In this paper, gas-phase reactions of deprotonated anions of benzene, pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine with N and O atoms are studied both experimentally and computationally. In all cases, the major reaction channel is associative electron detachment; these reactions are particularly important since they control the balance between negative ions and free electron densities. The reactions of the azine anions with N atoms exhibit larger rate constants than reactions of corresponding chain anions. The reactions of azine anions with O atoms are even more rapid, with complex product patterns for different reactants. The mechanisms are studied theoretically by employing density functional theory; spin conversion is found to be important in determining some product distributions. The rich gas-phase chemistry observed in this work provides a better understanding of ion-atom reactions and their contributions to ionospheric chemistry as well as the chemical processing that occurs in the boundary layers between diffuse and dense interstellar clouds. PMID:26281019

  13. XeCl laser ablation of polyimide: Influence of ambient atmosphere on particulate and gaseous products

    NASA Astrophysics Data System (ADS)

    Singleton, Donald L.; Paraskevopoulos, George; Irwin, Robert S.

    1989-10-01

    The gaseous and particulate products of the XeCl (308 nm) laser ablation of polyimide (Kapton H) are quantitatively determined and compared with the mass loss of the polymer in atmospheres of He, N2, air, or O2. In air and in pure O2, the observed mass balance is about 90%, but is lower for inert atmospheres. With increasing oxygen content in the atmosphere, the yield of CO2 increases at the expense of particulates and acetylene. The influence of laser fluence and nature of the ambient atmosphere on the product distribution is interpreted in terms of ejection of small reactive species which are involved in the competitive reactions of particulate formation and oxidation to CO2.

  14. Plant surface reactions: an ozone defence mechanism impacting atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Jud, W.; Fischer, L.; Canaval, E.; Wohlfahrt, G.; Tissier, A.; Hansel, A.

    2015-07-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants, responsible for global crop losses with associated economic costs of several billion dollars per year. Plant injuries have been linked to the uptake of ozone through stomatal pores and oxidative damage of the internal leaf tissue. But a striking question remains: how much ozone effectively enters the plant through open stomata and how much is lost by chemical reactions at the plant surface? In this laboratory study we could show that semi-volatile organic compounds exuded by the glandular trichomes of different Nicotiana tabacum varieties are an efficient ozone sink at the plant surface. In our experiments, different diterpenoid compounds were responsible for a strongly variety dependent ozone uptake of plants under dark conditions, when stomatal pores are almost closed. Surface reactions of ozone were accompanied by prompt release of oxygenated volatile organic compounds, which could be linked to the corresponding precursor compounds: ozonolysis of cis-abienol (C20H34O) - a diterpenoid with two exocyclic double bonds - caused emissions of formaldehyde (HCHO) and methyl vinyl ketone (C4H6O). The ring-structured cembratrien-diols (C20H34O2) with three endocyclic double bonds need at least two ozonolysis steps to form volatile carbonyls such as 4-oxopentanal (C5H8O2), which we could observe in the gas phase, too. Fluid dynamic calculations were used to model ozone distribution in the diffusion limited leaf boundary layer under daylight conditions. In the case of an ozone-reactive leaf surface, ozone gradients in the vicinity of stomatal pores are changed in such a way, that ozone flux through the open stomata is strongly reduced. Our results show that unsaturated semi-volatile compounds at the plant surface should be considered as a source of oxygenated volatile organic compounds, impacting gas phase chemistry, as well as efficient ozone sink improving the ozone tolerance of plants.

  15. Acid-Catalyzed Reaction of Epoxides on Atmospheric Nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, W.; Gomez-Hernandez, M.; Lal, V.; Qiu, C.; Khalizov, A. F.; Wang, L.; Zhang, R.

    2013-12-01

    Aerosol plays an important role in affecting the earth climate and harming human health. Atmospheric aerosols can be formed from either primary emissions or gas-to-particle conversion process. Numerous studies, including both experimental and theoretical, have been carried out to elucidate the mechanism of gas-to-particle conversion process (a.k.a. nucleation) and the later growth stage of newly formed nanoparticles. However, a complete list of species involving in the nucleation and growth processes of nanoparticles is still poorly understood. The growth of newly formed sulfuric acid - water nanoparticles has been suggested to involve several potential organic vapors, such as amines, glyoxal, 2-4 hexadienal, and epoxides. In the present study, new formed sulfuric acid -water nanoparticles were size selected by a differential mobility analyzer and exposed to epoxide vapors. The size-change after exposure was detected using the second differential mobility analyzer. The size-enlarged particles were then collected by an electrostatic precipitator, thermal vaporized, and analyzed by an ion drift chemical ionization mass spectrometer. Our results show that the sizes of nanoparticles are increased considerably and the magnitude of the increment in size is size-dependent. Mass spectrometry analysis of the nanoparticles after exposure demonstrates that low volatile organosulfate and oligomers are formed in nanoparticles upon their exposure to epoxide vapors.

  16. Step Towards Modeling the Atmosphere of Titan: State-Selected Reactions of O+ with Methane

    NASA Astrophysics Data System (ADS)

    Hrušák, J.; Paidarová, I.

    2016-04-01

    Methane conversion and in particular the formation of the C-O bond is one of fundamental entries to organic chemistry and it appears to be essential for understanding parts of atmospheric chemistry of Titan, but, in broader terms it might be also relevant for Earth-like exoplanets. Theoretical study of the reactions of methane with atomic oxygen ion in its excited electronic states requires treating simultaneously at least 19 electronic states. Development of a computational strategy that would allow chemically reasonable and computationally feasible treatment of the CH4 (X)/O+ (2D, 2P) system is by far not trivial and it requires careful examination of all the complex features of the corresponding 19 potential energy surfaces. Before entering the discussion of the rich (photo) chemistry, inspection of the long range behavior of the system with focus on electric dipole transition moments is required. Our calculations show nonzero probability for the reactants to decay before entering the multiple avoided crossings region of the [CH4 + O → products]+ reaction. For the CH4/O+ (2P) system non-zero transition moment probabilities occur over the entire range of considered C-O distances (up to 15 Å), while for the CH4/O+ (2D) system these probabilities are lower by one order of magnitude and were found only at C-O distances smaller than 6 Å.

  17. Mineralization of atmospheric CO2 via fluid reaction with mafic/ultramafic rocks

    NASA Astrophysics Data System (ADS)

    Westfield, I. T.; Kendall, T. A.; Ries, J. B.

    2011-12-01

    Atmospheric CO2 has increased nearly 50% since the Industrial Revolution, due primarily to increased fossil fuel combustion, cement production, and deforestation. Although subterranean reservoirs are presently considered the most viable sink for anthropogenically liberated CO2, concerns exist over the stability of these systems and their impacts on regional tectonics, aquifers, and subterranean microbial ecosystems. Direct mineralization of CO2 at the Earth's surface provides an alternative capable of generating useful carbon-negative mineral byproducts that may be used to supplement or replace conventional carbon-positive building materials, like cement. However, mineralization of anthropogenic CO2 requires large sources of alkalinity to convert CO2 to CO32-, and divalent cations (e.g., Mg2+, Ca2+, Fe2+, etc.) to bond with the aqueous CO32-. Ultramafic and mafic rocks, such as peridotites, serpentinites, and basalts, are globally abundant, naturally occurring sources of the divalent cations, and alkalinity required for CO2 mineralization. Here, we present the results of accelerated reactions between ultramafic/mafic rocks, water, and CO2/N2 gases, aimed at quantifying the carbonation potential of mafic/ultramafic rocks. Rock-fluid-gas batch reactions were carried out in vented 4 L borosilicate glass flasks filled with 3 L DI water and 200 g acetone-washed, 49-180μm-diameter grains of four ultramafic/mafic rock types: peridotite, dunite, websterite and basalt. Each of the four rock-water mixtures was reacted under pure CO2 and pure N2 and at 25 and 200 °C, for a total of 16 reactions. Mixtures were continuously heated and stirred for 14 days. Samples (330 mL) were obtained at 0, 1, 6, 24, 48, 96, 168, and 336 hrs and filtered at 0.4 μm. The pH of filtered samples was measured with a single-junction Ag/AgCl glass electrode, salinity was determined with a conductivity probe, total alkalinity (TA) was determined by closed-cell potentiometric Gran titration, and DIC

  18. Aqueous-Phase Photochemical Production of Oxidants in Atmospheric Waters.

    NASA Astrophysics Data System (ADS)

    Allen, John Morrison

    1992-01-01

    The photochemical formation and subsequent reactions of oxidants plays an important role in the overall chemistry of the atmosphere. Much of the interest in atmospheric oxidation reactions has been fueled by the environmental consequences of the oxidation of sulfur dioxide (SO _2) forming sulfuric acid (H_2 SO_4). Oxidation reactions also play a crucial role in other atmospheric chemical transformations such as: (1) the destruction of tropospheric ozone, (2) redox cycling of transition metals, and (3) oxidation of organic compounds. Much of the research pertaining to atmospheric oxidant formation and the reactions that these oxidants undergo has centered upon gas-phase photochemical oxidant formation and: (1) subsequent reactions in the gas phase, or (2) partitioning of oxidants into cloud and fog drops and subsequent reactions in the aqueous phase. Only a very limited amount of data is available concerning aqueous -phase photochemical sources of oxidants in cloud and fog drops. The focus of one aspect of the work presented in this dissertation is upon the aqueous-phase sunlight photochemical formation of oxidants in authentic cloud and fog water samples from across the United States and Canada. It will be demonstrated that atmospheric waters typically absorb solar ultraviolet radiation at wavelengths ranging from 290 to 340 nm. This absorption is due to the presence of chemical constituents in the cloud and fog waters that contain chromophoric functional groups that give rise to the formation of: (1) singlet molecular oxygen O_2(^1Delta_ {rm g}), (2) peroxyl radicals (HO _2cdot and RO_2 cdot), (3) peroxides (HOOH, ROOH, and ROOR '), and (4) hydroxyl radical ( cdotOH). This work will demonstrate that aqueous-phase photochemical reactions are a significant and in some cases dominant source of these oxidants in cloud and fog drops. The transition metal catalyzed oxidation of SO _2 to H_2SO _4 by molecular oxygen has been extensively studied. This reaction is thought

  19. Kinetics and Mechanism of the Reaction of Hydoxyl Radicals with Acetonitrile under Atmospheric Conditions

    NASA Technical Reports Server (NTRS)

    Hynes, A. J.; Wine, P. H.

    1997-01-01

    The pulsed laser photolysis-pulsed laser induced fluorescence technique has been employed to determine absolute rate coefficients for the reaction OH + CH3CN (1) and its isotopic variants, OH + CD3CN (2), OD + CH3CN (3), and OD + CD3CN (4). Reactions 1 and 2 were studied as a function of pressure and temperature in N2, N2/O2, and He buffer gases. In the absence of O2 all four reactions displayed well-behaved kinetics with exponential OH decays and pseudo-first rate constants which were proportional to substrate concentration. Data obtained in N2 over the range 50-700 Torr at 298 K are consistent with k(sub 1), showing a small pressure dependence. The Arrhenius expression obtained by averaging data at all pressures in k(sub 1)(T) = (1.1(sup +0.5)/(sub -0.3)) x 10(exp -12) exp[(-1130 +/- 90)/T] cu cm /(molecule s). The kinetics of reaction 2 are found to be pressure dependent with k(sub 2) (298 K) increasing from (1.21 +/- 0.12) x 10(exp -14) to (2.16 +/- 0.11) x 10(exp -14) cm(exp 3)/ (molecule s) over the pressure range 50-700 Torr of N2 at 298 K. Data at pressures greater than 600 Torr give k(sub 2)(T) = (9.4((sup +13.4)(sub -5.0))) x 10(exp -13) exp[(-1180 +/- 250)/T] cu cm/(molecule s). The rates of reactions 3 and 4 are found to be independent of pressure over the range 50-700 Torr of N2 with 298 K rate coefficient given by k(sub 3) =(3.18 +/- 0.40) x 10(exp -14) cu cm/(molecule s) and k(sub 4) = (2.25 +/-0.28) x 10(exp -14) cu cm/(molecule s). In the presence of O2 each reaction shows complex (non-pseudo-first-order) kinetic behavior and/or an apparent decrease in the observed rate constant with increasing [O2], indicating the presence of significant OH or OD regeneration. Observation of regeneration of OH in (2) and OD in (3) is indicative of a reaction channel which proceeds via addition followed by reaction of the adduct, or one of its decomposition products, with O2. The observed OH and OD decay profiles have been modeled by using a simple mechanistic

  20. Kinetic and photochemical data for atmospheric chemistry reactions of the nitrogen oxides

    NASA Technical Reports Server (NTRS)

    Hampson, R. F., Jr.

    1980-01-01

    Data sheets for thermal and photochemical reactions of importance in the atmospheric chemistry of the nitrogen oxides are presented. For each reaction the available experimental data are summarized and critically evaluated, and a preferred value of the rate coefficient is given. The selection of the preferred value is discussed and an estimate of its accuracy is given. For the photochemical process, the data are summarized, and preferred for the photoabsorption cross section and primary quantum yields are given.

  1. Low-temperature Kinetic Studies of OH Radical Reactions Relevant to Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Townsend, T. M.; Antiñolo, M.; Ballesteros, B.; Jimenez, E.; Canosa, A.

    2011-05-01

    In the solar system, the temperature (T) of the atmosphere of giant planets or their satellites is only several tens of Kelvin (K). The temperature of the tropopause of Titan (satellite of Saturn) and the surface of Mars is 70 K and 210 K, respectively. In the Earth's atmosphere, T decreases from 298 K (surface) to 210 K close to the T-inversion region (tropopause). The principal oxidants in the Earth's lower atmosphere are ozone, the hydroxyl (OH) radical and hydrogen peroxide. A number of critical atmospheric chemical problems depend on the Earth's oxidising capacity, which is essentially the global burden of these oxidants. In the interstellar clouds and circumstellar envelopes, OH radicals have also been detected. As the chemistry of atmospheres is highly influenced by temperature, the knowledge of the T-dependence of the rate coefficients for OH-reactions (k) is the key to understanding the underlying molecular mechanisms. In general, these reactions take place on a short temporal scale. Therefore, a detection technique with high temporal resolution is required. Measurements of k at low temperatures can be achieved by maintaining a thermalised environment using either cryogenic cooling (T>200 K) or supersonic gas expansion with a Laval nozzle (several tens of K). The pulsed laser photolysis technique coupled with laser induced fluorescence detection has been widely used in our laboratory to determine the rate coefficients of OH-reactions with different volatile organic compounds, such as alcohols (1), saturated and unsaturated aliphatic aldehydes (2), linear ketones (3), as a function of temperature (260 350 K). An experimental system based on the CRESU (Cinetique de Reaction en Ecoulement Supersonique Uniforme or Reaction Kinetics in a Uniform Supersonic Flow) technique is currently under construction. This technique will allow the performance of kinetic studies of OH-reactions of astrophysical interest at temperatures lower than 200 K.

  2. Adsorption and reaction of trace gas-phase organic compounds on atmospheric water film surfaces: a critical review.

    PubMed

    Donaldson, D J; Valsaraj, Kalliat T

    2010-02-01

    The air-water interface in atmospheric water films of aerosols and hydrometeors (fog, mist, ice, rain, and snow) presents an important surface for the adsorption and reaction of many organic trace gases and gaseous reactive oxidants (hydroxyl radical (OH(.)), ozone (O(3)), singlet oxygen (O(2)((1)Delta(g))), nitrate radicals (NO(3)(.)), and peroxy radicals (RO(2)(.)). Knowledge of the air-water interface partition constant of hydrophobic organic species is necessary for elucidating the significance of the interface in atmospheric fate and transport. Various methods of assessing both experimental and theoretical values of the thermodynamic partition constant and adsorption isotherm are described in this review. Further, the reactivity of trace gases with gas-phase oxidants (ozone and singlet oxygen) at the interface is summarized. Oxidation products are likely to be more water-soluble and precursors for secondary organic aerosols in hydrometeors. Estimation of characteristic times shows that heterogeneous photooxidation in water films can compete effectively with homogeneous gas-phase reactions for molecules in the atmosphere. This provides further support to the existing thesis that reactions of organic compounds at the air-water interface should be considered in gas-phase tropospheric chemistry. PMID:20058916

  3. Aqueous-Phase Reactions of Isoprene with Sulfoxy Radical Anions as a way of Wet Aerosol Formation in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Kuznietsova, I.; Rudzinski, K. J.; Szmigielski, R.; Laboratory of the Environmental Chemistry

    2011-12-01

    Atmospheric aerosols exhibit an important role in the environment. They have implications on human health and life, and - in the larger scale - on climate, the Earth's radiative balance and the cloud's formation. Organic matter makes up a significant fraction of atmospheric aerosols (~35% to ~90%) and may originate from direct emissions (primary organic aerosol, POA) or result from complex physico-chemical processes of volatile organic compounds (secondary organic aerosol, SOA). Isoprene (2-methyl-buta-1,3-diene) is one of the relevant volatile precursor of ambient SOA in the atmosphere. It is the most abundant non-methane hydrocarbon emitted to the atmosphere as a result of living vegetation. According to the recent data, the isoprene emission rate is estimated to be at the level of 500 TgC per year. While heterogeneous transformations of isoprene have been well documented, aqueous-phase reactions of this hydrocarbon with radical species that lead to the production of new class of wet SOA components such as polyols and their sulfate esters (organosulfates), are still poorly recognized. The chain reactions of isoprene with sulfoxy radical-anions (SRA) are one of the recently researched route leading to the formation of organosulfates in the aqueous phase. The letter radical species originate from the auto-oxidation of sulfur dioxide in the aqueous phase and are behind the phenomenon of atmospheric acid rain formation. This is a complicated chain reaction that is catalyzed by transition metal ions, such as manganese(II), iron(III) and propagated by sulfoxy radical anions . The presented work addresses the chemical interaction of isoprene with sulfoxy radical-anions in the water solution in the presence of nitrite ions and nitrous acid, which are important trace components of the atmosphere. We showed that nitrite ions and nitrous acid significantly altered the kinetics of the auto-oxidation of SO2 in the presence of isoprene at different solution acidity from 2 to 8

  4. Mutagenicity in Salmonella of a Simulated Urban-Smog Atmosphere Generated Using a Mobile Reaction Chamber

    EPA Science Inventory

    The EPA Mobile Reaction Chamber (MRC) is a 24-foot trailer containing a 14.3-m3 Teflon lined photochemical chamber used to generate simulated urban atmospheres. Photochemistry in the MRC is catalyzed by 120 fluorescent bulbs evenly mixed with black light bulbs and UV bulbs (300 &...

  5. Comment on 'Middle atmosphere heating by exothermic chemical reactions involving odd-hydrogen species'

    NASA Astrophysics Data System (ADS)

    McDade, Ian C.; Llewellyn, Edward J.

    1991-09-01

    It is shown that the H + O3 heating efficiencies calculated using the McDade and Llewellyn (1987) and Lopez-Moreno et al. (1987) Meinel band models are very similar. This result corroborates the Mlynczak and Solomon (1991) thesis that the H + O3 reaction must be a significant source of heat in the middle atmosphere.

  6. Reactions between Criegee Intermediates and the Inorganic Acids HCl and HNO3 : Kinetics and Atmospheric Implications.

    PubMed

    Foreman, Elizabeth S; Kapnas, Kara M; Murray, Craig

    2016-08-22

    Criegee intermediates (CIs) are a class of reactive radicals that are thought to play a key role in atmospheric chemistry through reactions with trace species that can lead to aerosol particle formation. Recent work has suggested that water vapor is likely to be the dominant sink for some CIs, although reactions with trace species that are sufficiently rapid can be locally competitive. Herein, we use broadband transient absorption spectroscopy to measure rate constants for the reactions of the simplest CI, CH2 OO, with two inorganic acids, HCl and HNO3 , both of which are present in polluted urban atmospheres. Both reactions are fast; at 295 K, the reactions of CH2 OO with HCl and HNO3 have rate constants of 4.6×10(-11)  cm(3)  s(-1) and 5.4×10(-10)  cm(3)  s(-1) , respectively. Complementary quantum-chemical calculations show that these reactions form substituted hydroperoxides with no energy barrier. The results suggest that reactions of CIs with HNO3 in particular are likely to be competitive with those with water vapor in polluted urban areas under conditions of modest relative humidity. PMID:27440012

  7. A new transitory product in the ozonolysis of trans-2-butene at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Horie, O.; Moortgat, G. K.

    1989-03-01

    A previously unidentified transitory species, tentatively assigned as hydroxyethyl formate, CH 3CH (OH)-O-CHO, was formed as a major product in the ozonolysis of trans-2-butene at atmospheric pressure. A continuous stirred-tank reactor was used to analyze reaction products via molecular-beam sampling and matrix isolation FTIR spectroscopy. CH 3CHO, HCHO, CO 2, CO, CH 3OH, CH 4 and H 2O were the main, HCOOH and CH 2CO the minor, products. CH 3COOH and propene ozonide were detected as trace components.

  8. Comprehensive NO-dependent study of the products of the oxidation of atmospherically relevant aromatic compounds.

    PubMed

    Birdsall, Adam W; Elrod, Matthew J

    2011-06-01

    A comprehensive product study, performed via the turbulent flow chemical ionization mass spectrometry (TF-CIMS) technique, of the primary OH-initiated oxidation of many of the atmospherically abundant aromatic compounds was performed. The bicyclic peroxy radical intermediate, a key proposed intermediate species in the Master Chemical Mechanism (MCM) for the atmospheric oxidation of aromatics, was detected in all cases, as were stable bicyclic species. The NO product yield dependences suggest a potential role for bicyclic peroxy radical + HO(2) reactions at high HO(2)/NO ratios, which are postulated to be a possible source of the inconsistencies between previous environmental chamber results and predictions from the MCM for ozone production and OH reactivity. The TF-CIMS product yield results are also compared to previous environment chamber results and to the latest MCM parametrization. PMID:21553858

  9. Products of the Benzene + O(3P) Reaction

    SciTech Connect

    Taatjes, Craig A.; Osborn, David L.; Selby, Talitha M.; Meloni, Giovanni; Trevitt, Adam J.; Epifanovsky, Evgeny; Krylov, Anna I.; Sirjean, Baptiste; Dames, Enoch; Wang, Hai

    2009-12-21

    The gas-phase reaction of benzene with O(3P) is of considerable interest for modeling of aromatic oxidation, and also because there exist fundamental questions concerning the prominence of intersystem crossing in the reaction. While its overall rate constant has been studied extensively, there are still significant uncertainties in the product distribution. The reaction proceeds mainly through the addition of the O atom to benzene, forming an initial triplet diradical adduct, which can either dissociate to form the phenoxy radical and H atom, or undergo intersystem crossing onto a singlet surface, followed by a multiplicity of internal isomerizations, leading to several possible reaction products. In this work, we examined the product branching ratios of the reaction between benzene and O(3P) over the temperature range of 300 to 1000 K and pressure range of 1 to 10 Torr. The reactions were initiated by pulsed-laser photolysis of NO2 in the presence of benzene and helium buffer in a slow-flow reactor, and reaction products were identified by using the multiplexed chemical kinetics photoionization mass spectrometer operating at the Advanced Light Source (ALS) of Lawrence Berkeley National Laboratory. Phenol and phenoxy radical were detected and quantified. Cyclopentadiene and cyclopentadienyl radical were directly identified for the first time. Finally, ab initio calculations and master equation/RRKM modeling were used to reproduce the experimental branching ratios, yielding pressure-dependent rate expressions for the reaction channels, including phenoxy + H, phenol, cyclopentadiene + CO, which are proposed for kinetic modeling of benzene oxidation.

  10. Production of extremely low volatile organic compounds from biogenic emissions: Measured yields and atmospheric implications

    PubMed Central

    Jokinen, Tuija; Berndt, Torsten; Makkonen, Risto; Kerminen, Veli-Matti; Junninen, Heikki; Stratmann, Frank; Herrmann, Hartmut; Guenther, Alex B.; Worsnop, Douglas R.; Kulmala, Markku; Ehn, Mikael; Sipilä, Mikko

    2015-01-01

    Oxidation products of monoterpenes and isoprene have a major influence on the global secondary organic aerosol (SOA) burden and the production of atmospheric nanoparticles and cloud condensation nuclei (CCN). Here, we investigate the formation of extremely low volatility organic compounds (ELVOC) from O3 and OH radical oxidation of several monoterpenes and isoprene in a series of laboratory experiments. We show that ELVOC from all precursors are formed within the first minute after the initial attack of an oxidant. We demonstrate that under atmospherically relevant concentrations, species with an endocyclic double bond efficiently produce ELVOC from ozonolysis, whereas the yields from OH radical-initiated reactions are smaller. If the double bond is exocyclic or the compound itself is acyclic, ozonolysis produces less ELVOC and the role of the OH radical-initiated ELVOC formation is increased. Isoprene oxidation produces marginal quantities of ELVOC regardless of the oxidant. Implementing our laboratory findings into a global modeling framework shows that biogenic SOA formation in general, and ELVOC in particular, play crucial roles in atmospheric CCN production. Monoterpene oxidation products enhance atmospheric new particle formation and growth in most continental regions, thereby increasing CCN concentrations, especially at high values of cloud supersaturation. Isoprene-derived SOA tends to suppress atmospheric new particle formation, yet it assists the growth of sub-CCN-size primary particles to CCN. Taking into account compound specific monoterpene emissions has a moderate effect on the modeled global CCN budget. PMID:26015574

  11. Production of extremely low volatile organic compounds from biogenic emissions: Measured yields and atmospheric implications.

    PubMed

    Jokinen, Tuija; Berndt, Torsten; Makkonen, Risto; Kerminen, Veli-Matti; Junninen, Heikki; Paasonen, Pauli; Stratmann, Frank; Herrmann, Hartmut; Guenther, Alex B; Worsnop, Douglas R; Kulmala, Markku; Ehn, Mikael; Sipilä, Mikko

    2015-06-01

    Oxidation products of monoterpenes and isoprene have a major influence on the global secondary organic aerosol (SOA) burden and the production of atmospheric nanoparticles and cloud condensation nuclei (CCN). Here, we investigate the formation of extremely low volatility organic compounds (ELVOC) from O3 and OH radical oxidation of several monoterpenes and isoprene in a series of laboratory experiments. We show that ELVOC from all precursors are formed within the first minute after the initial attack of an oxidant. We demonstrate that under atmospherically relevant concentrations, species with an endocyclic double bond efficiently produce ELVOC from ozonolysis, whereas the yields from OH radical-initiated reactions are smaller. If the double bond is exocyclic or the compound itself is acyclic, ozonolysis produces less ELVOC and the role of the OH radical-initiated ELVOC formation is increased. Isoprene oxidation produces marginal quantities of ELVOC regardless of the oxidant. Implementing our laboratory findings into a global modeling framework shows that biogenic SOA formation in general, and ELVOC in particular, play crucial roles in atmospheric CCN production. Monoterpene oxidation products enhance atmospheric new particle formation and growth in most continental regions, thereby increasing CCN concentrations, especially at high values of cloud supersaturation. Isoprene-derived SOA tends to suppress atmospheric new particle formation, yet it assists the growth of sub-CCN-size primary particles to CCN. Taking into account compound specific monoterpene emissions has a moderate effect on the modeled global CCN budget. PMID:26015574

  12. Reactivity of CHI3 with OH radicals: X-abstraction reaction pathways (X = H, I), atmospheric chemistry, and nuclear safety.

    PubMed

    Sudolská, Mária; Louis, Florent; Cernušák, Ivan

    2014-10-01

    The X-abstraction (X = H, I) pathways in the reaction of CHI3 with OH radical, a possible iodoform removal process relevant to the Earth's atmosphere and conditions prevailing in the case of a nuclear accident, have been studied applying highly correlated ab initio quantum chemistry methods and canonical transition-state theory to obtain reaction energy profiles and rate constants. Geometry optimizations of reactants, products, molecular complexes, and transition states determined at the MP2/cc-pVTZ level of theory have been followed by DK-CCSD(T)/ANO-RCC single-point energy calculations. Further improvement of electronic energies has been achieved by applying spin-orbit coupling, corrections toward full configuration interaction, vibration contributions, and tunneling corrections. Calculated reaction enthalpies at 0 K are -108.2 and -5.1 kJ mol(-1) for the H- and I-abstraction pathways, respectively; the strongly exothermic H-abstraction pathway is energetically favored over the modestly exothermic I-abstraction one. The overall rate constant at 298 K based on our ab initio calculations is 4.90 × 10(-11) cm(3) molecule(-1) s(-1), with the I-abstraction pathway being the major channel over the temperature range of 250-2000 K. The CHI3 atmospheric lifetime with respect to the removal reaction with OH radical is predicted to be about 6 h, very short compared to that of other halomethanes. PMID:25207959

  13. Reaction rate and products for the reaction O/3P/ + H2CO

    NASA Technical Reports Server (NTRS)

    Chang, J. S.; Barker, J. R.

    1979-01-01

    A study of reaction kinetics of O + H2CO in a discharge-flow system using mass spectrometric detection of reactants and products is presented. It was performed under both oxygen-atom-rich and formaldehyde-rich conditions over the 296 to 437 K range, showing that the global bimolecular rate constant is in agreement with other studies. This study differs from others in that the reaction products can be observed, and a substantial yield of a primary reaction product was measured with a mass spectral peak at m/e=44. This suggests that the global reaction rate probably consists of combination, as well as of simple abstraction. For the combination, one hypothesis is that triplet dioxymethylene is formed which polymerizes to triplet formic acid; the vibrationally excited triplet formic acid may decompose to form several sets of products, including HCO + OH and HCO2 + H.

  14. PRODUCTS OF THE GAS-PHASE REACTIONS OF THE OH RADICAL WITH N-BUTYL METHYL ETHER AND 2-ISOPROPOXYETHANOL: REACTIONS OF ROC(O)< RADICALS. (R825252)

    EPA Science Inventory

    The products of the gas-phase reactions of the OH radical with n-butyl methyl ether and 2-isopropoxyethanol in the presence of NO have been investigated at 298 ? 2 K and 740 Torr total pressure of air by gas chromatography and in situ atmospheric pressure ionization...

  15. The Influence of CO2 Admixtures on the Product Composition in a Nitrogen-Methane Atmospheric Glow Discharge Used as a Prebiotic Atmosphere Mimic

    NASA Astrophysics Data System (ADS)

    Mazankova, V.; Torokova, L.; Krcma, F.; Mason, N. J.; Matejcik, S.

    2016-04-01

    This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).

  16. Field and Laboratory Studies of Reactions between Atmospheric Water Soluble Organic Acids and Inorganic Particles

    SciTech Connect

    Wang, Bingbing; Kelly, Stephen T.; Sellon, Rachel E.; Shilling, John E.; Tivanski, Alexei V.; Moffet, Ryan C.; Gilles, Mary K.; Laskin, Alexander

    2013-06-25

    Atmospheric inorganic particles undergo complex heterogeneous reactions that change their physicochemical properties. Depletion of chloride in sea salt particles was reported in previous field studies and was attributed to the acid displacement of chlorides with inorganic acids, such as nitric and sulfuric acids [1-2]. Recently, we showed that NaCl can react with water soluble organic acids (WSOA) and release gaseous hydrochloric acid (HCl) resulting in formation of organic salts [3]. A similar mechanism is also applicable to mixed WSOA/nitrate particles where multi-phase reactions are driven by the volatility of nitric acid. Furthermore, secondary organic material, which is a complex mixture of carboxylic acids, exhibits the same reactivity towards chlorides and nitrates. Here, we present a systematic study of reactions between atmospheric relevant WSOA, SOM, and inorganic salts including NaCl, NaNO3, and Ca(NO3)2 using complementary micro-spectroscopy analysis.

  17. Atmospheric chemistry. Direct kinetic measurement of the reaction of the simplest Criegee intermediate with water vapor.

    PubMed

    Chao, Wen; Hsieh, Jun-Ting; Chang, Chun-Hung; Lin, Jim Jr-Min

    2015-02-13

    Carbonyl oxides, or Criegee intermediates, are important transient species formed in the reactions of unsaturated hydrocarbons with ozone. Although direct detection of Criegee intermediates has recently been realized, the main atmospheric sink of Criegee intermediates remains unclear. We report ultraviolet absorption spectroscopic measurements of the lifetime of the simplest Criegee intermediate, CH2OO, at various relative humidity levels up to 85% at 298 kelvin. An extremely fast decay rate of CH2OO was observed at high humidity. The observed quadratic dependence of the decay rate on water concentration implied a predominant reaction with water dimer. On the basis of the water dimer equilibrium constant, the effective rate coefficient of the CH2OO + (H2O)2 reaction was determined to be 6.5 (±0.8) × 10(-12) cubic centimeters per second. This work would help modelers to better constrain the atmospheric concentrations of CH2OO. PMID:25569112

  18. Using commercial software products for atmospheric remote sensing

    NASA Astrophysics Data System (ADS)

    Kristl, Joseph A.; Tibaudo, Cheryl; Tang, Kuilian; Schroeder, John W.

    2002-02-01

    The Ontar Corporation (www.Ontar.com) has developed several products for atmospheric remote sensing to calculate radiative transport, atmospheric transmission, and sensor performance in both the normal atmosphere and the atmosphere disturbed by battlefield conditions of smoke, dust, explosives and turbulence. These products include: PcModWin: Uses the USAF standard MODTRAN model to compute the atmospheric transmission and radiance at medium spectral resolution (2 cm-1) from the ultraviolet/visible into the infrared and microwave regions of the spectrum. It can be used for any geometry and atmospheric conditions such as aerosols, clouds and rain. PcLnWin: Uses the USAF standard FASCOD model to compute atmospheric transmission and emission at high (line-by-line) spectral resolution using the HITRAN 2000 database. It can be used over the same spectrum from the UV/visible into the infrared and microwave regions of the spectrum. HitranPC: Computes the absolute high (line-by-line) spectral resolution transmission spectrum of the atmosphere for different temperatures and pressures. HitranPC is a user-friendly program developed by the University of South Florida (USF) and uses the international standard molecular spectroscopic database, HITRAN. LidarPC: A computer program to calculate the Laser Radar/L&n Equation for hard targets and atmospheric backscatter using manual input atmospheric parameters or HitranPC and BETASPEC - transmission and backscatter calculations of the atmosphere. Also developed by the University of South Florida (USF). PcEosael: is a library of programs that mathematically describe aspects of electromagnetic propagation in battlefield environments. 25 modules are connected but can be exercised individually. Covers eight general categories of atmospheric effects, including gases, aerosols and laser propagation. Based on codes developed by the Army Research Lab. NVTherm: NVTherm models parallel scan, serial scan, and staring thermal imagers that operate

  19. Quality Assessment of Collection 6 MODIS Atmospheric Science Products

    NASA Astrophysics Data System (ADS)

    Manoharan, V. S.; Ridgway, B.; Platnick, S. E.; Devadiga, S.; Mauoka, E.

    2015-12-01

    Since the launch of the NASA Terra and Aqua satellites in December 1999 and May 2002, respectively, atmosphere and land data acquired by the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor on-board these satellites have been reprocessed five times at the MODAPS (MODIS Adaptive Processing System) located at NASA GSFC. The global land and atmosphere products use science algorithms developed by the NASA MODIS science team investigators. MODAPS completed Collection 6 reprocessing of MODIS Atmosphere science data products in April 2015 and is currently generating the Collection 6 products using the latest version of the science algorithms. This reprocessing has generated one of the longest time series of consistent data records for understanding cloud, aerosol, and other constituents in the earth's atmosphere. It is important to carefully evaluate and assess the quality of this data and remove any artifacts to maintain a useful climate data record. Quality Assessment (QA) is an integral part of the processing chain at MODAPS. This presentation will describe the QA approaches and tools adopted by the MODIS Land/Atmosphere Operational Product Evaluation (LDOPE) team to assess the quality of MODIS operational Atmospheric products produced at MODAPS. Some of the tools include global high resolution images, time series analysis and statistical QA metrics. The new high resolution global browse images with pan and zoom have provided the ability to perform QA of products in real time through synoptic QA on the web. This global browse generation has been useful in identifying production error, data loss, and data quality issues from calibration error, geolocation error and algorithm performance. A time series analysis for various science datasets in the Level-3 monthly product was recently developed for assessing any long term drifts in the data arising from instrument errors or other artifacts. This presentation will describe and discuss some test cases from the

  20. Exploiting the reversibility of natural product glycosyltransferase-catalyzed reactions.

    PubMed

    Zhang, Changsheng; Griffith, Byron R; Fu, Qiang; Albermann, Christoph; Fu, Xun; Lee, In-Kyoung; Li, Lingjun; Thorson, Jon S

    2006-09-01

    Glycosyltransferases (GTs), an essential class of ubiquitous enzymes, are generally perceived as unidirectional catalysts. In contrast, we report that four glycosyltransferases from two distinct natural product biosynthetic pathways-calicheamicin and vancomycin-readily catalyze reversible reactions, allowing sugars and aglycons to be exchanged with ease. As proof of the broader applicability of these new reactions, more than 70 differentially glycosylated calicheamicin and vancomycin variants are reported. This study suggests the reversibility of GT-catalyzed reactions may be general and useful for generating exotic nucleotide sugars, establishing in vitro GT activity in complex systems, and enhancing natural product diversity. PMID:16946071

  1. Atmospheric degradation of alkylfurans with chlorine atoms: Product and mechanistic study

    NASA Astrophysics Data System (ADS)

    Villanueva, F.; Cabañas, B.; Monedero, E.; Salgado, S.; Bejan, I.; Martin, P.

    As part of a study on the oxidation mechanism of heterocyclic aromatic compounds, some aspects of the atmospheric chemistry of several alkyl derivatives of furan have been investigated. The aim of this work was to identify the products of the reactions of chlorine atoms with 2-methylfuran, 2-ethylfuran and 2,5-dimethylfuran. Experiments were performed in two different smog chambers at 296 ± 2 K and 1000 ± 20 mbar of synthetic air. The experimental investigation was carried out using in situ long-path FTIR absorption spectroscopy and both SPME-GC/FID-ECD and SPME-GC/MS as sampling and detection techniques. The major primary products from the addition reaction channel were 4-oxo-2-pentenoyl chloride and formaldehyde for the reactions of 2-methylfuran and 2,5-dimethylfuran; 4-oxo-2-hexenoyl chloride and acetaldehyde for the reaction of 2-ethylfuran and 5-chloro-2(5H)-furanone for the reactions of both 2-methylfuran and 2-ethylfuran. Other minor products were 4-oxo-2-pentenal, 4-oxo-2-hexenal and 3-hexene-2,5-dione for the 2-methylfuran, 2-ethylfuran and 2,5-dimethylfuran reactions, respectively. From the abstraction pathway, HCl, furfural, 2-acetylfuran, 5-methylfurfural, maleic anhydride and 5-hydroxy-2(5H)-furanone were detected. The formation of furfural, 2-acetylfuran and 5-methylfurfural confirmed the H-atom abstraction from the alkyl group of 2-methylfuran, 2-ethylfuran and 2,5-dimethylfuran, respectively. This mechanism was not observed in previous studies with OH and NO 3 radicals. A mechanism is proposed to explain the main reaction products observed. The observed products confirm that addition of Cl atoms to the double bond of the alkylfuran is the dominant reaction pathway.

  2. Heterogeneous production of cloud condensation nuclei in the marine atmosphere

    SciTech Connect

    Hegg, D.A. )

    1990-11-01

    Model calculations are presented which indicate that newly created particles in the marine atmosphere will commonly only be able to achieve sizes, by means of gas-phase processes, sufficient to activate a cumuliform clouds. Aqueous sulfate production in such clouds will be generally necessary to grow them large enough to activate in marine stratus clouds.

  3. Evolutionary pressures on planktonic production of atmospheric sulphur

    NASA Astrophysics Data System (ADS)

    Caldeira, Ken

    1989-02-01

    The possibility that dimethylsulphide (DMS) produced by marine phytoplankton is the major source of cloud condensation nuclei in the remote marine atmosphere is examined. Calculations of relative evolutionary pressure in models of individual and group selection are reviewed, showing that neither climate modulation nor altruism cloud have been the primary factors in the evolution of midocean DMS production. It is found that the midocean DMS production can be explained by selection based on local interactions such as osmoregulation.

  4. The atmospheric chemistry of methyl salicylate—reactions with atomic chlorine and with ozone

    NASA Astrophysics Data System (ADS)

    Canosa-Mas, Carlos E.; Duffy, Justin M.; King, Martin D.; Thompson, Katherine C.; Wayne, Richard P.

    Methyl salicylate is one of a number of semiochemicals, signal molecules, emitted by herbivore-infested plants. These signal molecules attract predators of the herbivore, and the chemicals thus act indirectly as part of the defence mechanism of the plant. Previous studies have shown that ozone damage to plants can also elicit the emission of signal molecules. The fate of these signal molecules in the atmosphere is not known. Preliminary studies have been undertaken to examine the atmospheric chemistry of methyl salicylate for the first time. Rate coefficients for the reaction of methyl salicylate with atomic chlorine and with ozone have been determined; the values are (2.8±0.3)×10 -12 and ˜4×10 -21 cm 3 molecule -1 s -1. These results suggest that neither reaction with atomic chlorine nor reaction with ozone will provide important loss routes for methyl salicylate in the atmosphere. The possible importance of photolysis of methyl salicylate in the atmosphere is considered.

  5. Positive feedback between increasing atmospheric CO2 and ecosystem productivity

    NASA Astrophysics Data System (ADS)

    Gelfand, I.; Hamilton, S. K.; Robertson, G. P.

    2009-12-01

    Increasing atmospheric CO2 will likely affect both the hydrologic cycle and ecosystem productivity. Current assumptions that increasing CO2 will lead to increased ecosystem productivity and plant water use efficiency (WUE) are driving optimistic predictions of higher crop yields as well as greater availability of freshwater resources due to a decrease in evapotranspiration. The plant physiological response that drives these effects is believed to be an increase in carbon uptake either by (a) stronger CO2 gradient between the stomata and the atmosphere, or by (b) reduced CO2 limitation of enzymatic carboxylation within the leaf. The (a) scenario will lead to increased water use efficiency (WUE) in plants. However, evidence for increased WUE is mostly based on modeling studies, and experiments producing a short duration or step-wise increase in CO2 concentration (e.g. free-air CO2 enrichment). We hypothesize that the increase in atmospheric CO2 concentration is having a positive effect on ecosystem productivity and WUE. To investigate this hypothesis, we analyzed meteorological, ANPP, and soil CO2 flux datasets together with carbon isotopic ratio (13C/12C) of archived plant samples from the long term ecological research (LTER) program at Kellogg Biological Station. The datasets were collected between 1989 and 2007 (corresponding to an increase in atmospheric CO2 concentration of ~33 ppmv at Mauna Loa). Wheat (Triticum aestivum) samples taken from 1989 and 2007 show a significant decrease in the C isotope discrimination factor (Δ) over time. Stomatal conductance is directly related to Δ, and thus Δ is inversely related to plant intrinsic WUE (iWUE). Historical changes in the 13C/12C ratio (δ13C) in samples of a perennial forb, Canada goldenrod (Solidago canadensis), taken from adjacent successional fields, indicate changes in Δ upon uptake of CO2 as well. These temporal trends in Δ suggest a positive feedback between the increasing CO2 concentration in the

  6. Critical Evaluation of Chemical Reaction Rates and Collision Cross Sections of Importance in the Earth's Upper Atmosphere and the Atmospheres of Other Planets, Moons, and Comets

    NASA Astrophysics Data System (ADS)

    Huestis, D. L.

    2005-05-01

    We recommend establishment of a long-term program of critical evaluation by domain experts of the rates and cross sections of atomic and molecular processes that are needed for understanding and modeling the atmospheres in the solar system. We envision products resembling those from the ongoing JPL/NASA Panel for Data Evaluation and the efforts of the international combustion modeling community funded by US DOE and its European counterpart. Both of these endeavors already provide some important inputs for modeling the atmospheres of the Earth, planets, moons, and comets. However, their applications restrict the choice of which processes to evaluate and the temperature and pressure ranges to cover, thus leaving large gaps that need to be filled. Interestingly, an older evaluation program once filled some of these gaps. Funded by the US DoD in the 1960s-1980s, the DNA Reaction Rate Handbook provided a thorough treatment of numerous types of collisions and reactions that are important in the Earth's lower ionosphere, and the program even provided funding for new laboratory measurements. Other examples could be given, with the on-line resources at NIST being among the best, but most provide a narrower scope or less critical evaluation. What is needed is not a just a list of processes and numbers (i.e., a "database"), but rather serious comparison of the available information and specific statements from independent expert laboratory/theory data providers about what should be believed, what uncertainty to assign, and what is most in need of redetermination. The major topic areas would include the following: 1. Chemical reactions of neutral atoms and molecules in their ground electronic states 2. Ion-molecule reactions 3. Chemistry, relaxation, and radiation of electronically excited atoms and molecules 4. Vibrational and rotational relaxation and radiation 5. Photoabsorption, photodissociation, and photoionization 6. Electron-impact excitation, dissociation, ionization

  7. A photochemical study of the kinetics of the reactions of NH2 with phosphine, ethylene, and acetylene using flash photolysis-laser induced fluorescence. Ph.D. Thesis Catholic Univ. of America; [ammonia in the atmosphere of Jupiter

    NASA Technical Reports Server (NTRS)

    Bosco, S. R.

    1982-01-01

    The photochemistry of the reactions of NH2 was investigated in an attempt to explain the existence of an abundance of ammonia in the Jovian atmosphere. The production of ammonia reservoirs from the coupling of ammonia with other atmospheric constituents was considered. The rate constants for the reactions of NH2 radicals with phosphine, acetylene, and ethylene were measured. Flash photolysis was used for the production of NH2 radicals and laser induced fluorescence was employed for radical detection. It was determined that the rates of the reactions were too slow to be significant as a source of ammonia reservoirs in the Jovian atmosphere.

  8. Application of an atmospheric pressure sampling mass spectrometer to chlorination reactions

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.

    1986-01-01

    An atmospheric pressure mass spectrometric sampling system, based on a free jet expansion was used to study certain M-Cl-O reactions at high temperatures. The apparatus enables the volatile species from a 1-atm chemical process to be directly identified with a mass spectrometer which operates at approx. 10 to the minus 8th power torr. Studies for both pure metals and alloys are discussed. It is shown that this mass spectrometer system aids in identifying the volatile species, and provides fundamental information on the reaction mechanism.

  9. Modelling of OH production in cold atmospheric-pressure He-H2O plasma jets

    NASA Astrophysics Data System (ADS)

    Naidis, G. V.

    2013-06-01

    Results of the modelling of OH production in the plasma bullet mode of cold atmospheric-pressure He-H2O plasma jets are presented. It is shown that the dominant source of OH molecules is related to the Penning and charge transfer reactions of H2O molecules with excited and charged helium species produced by guided streamers (plasma bullets), in contrast to the case of He-H2O glow discharges where OH production is mainly due to the dissociation of H2O molecules by electron impact.

  10. Reactions of substituted benzene anions with N and O atoms: Chemistry in Titan's upper atmosphere and the interstellar medium

    NASA Astrophysics Data System (ADS)

    Wang, Zhe-Chen; Bierbaum, Veronica M.

    2016-06-01

    The likely existence of aromatic anions in many important extraterrestrial environments, from the atmosphere of Titan to the interstellar medium (ISM), is attracting increasing attention. Nitrogen and oxygen atoms are also widely observed in the ISM and in the ionospheres of planets and moons. In the current work, we extend previous studies to explore the reactivity of prototypical aromatic anions (deprotonated toluene, aniline, and phenol) with N and O atoms both experimentally and computationally. The benzyl and anilinide anions both exhibit slow associative electron detachment (AED) processes with N atom, and moderate reactivity with O atom in which AED dominates but ionic products are also formed. The reactivity of phenoxide is dramatically different; there is no measurable reaction with N atom, and the moderate reactivity with O atom produces almost exclusively ionic products. The reaction mechanisms are studied theoretically by employing density functional theory calculations, and spin conversion is found to be critical for understanding some product distributions. This work provides insight into the rich gas-phase chemistry of aromatic ion-atom reactions and their relevance to ionospheric and interstellar chemistry.

  11. Reactions of substituted benzene anions with N and O atoms: Chemistry in Titan's upper atmosphere and the interstellar medium.

    PubMed

    Wang, Zhe-Chen; Bierbaum, Veronica M

    2016-06-01

    The likely existence of aromatic anions in many important extraterrestrial environments, from the atmosphere of Titan to the interstellar medium (ISM), is attracting increasing attention. Nitrogen and oxygen atoms are also widely observed in the ISM and in the ionospheres of planets and moons. In the current work, we extend previous studies to explore the reactivity of prototypical aromatic anions (deprotonated toluene, aniline, and phenol) with N and O atoms both experimentally and computationally. The benzyl and anilinide anions both exhibit slow associative electron detachment (AED) processes with N atom, and moderate reactivity with O atom in which AED dominates but ionic products are also formed. The reactivity of phenoxide is dramatically different; there is no measurable reaction with N atom, and the moderate reactivity with O atom produces almost exclusively ionic products. The reaction mechanisms are studied theoretically by employing density functional theory calculations, and spin conversion is found to be critical for understanding some product distributions. This work provides insight into the rich gas-phase chemistry of aromatic ion-atom reactions and their relevance to ionospheric and interstellar chemistry. PMID:27276954

  12. Reactions of SIV species with organic compounds: formation mechanisms of organo-sulfur derivatives in atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Passananti, Monica; Shang, Jing; Dupart, Yoan; Perrier, Sébastien; George, Christian

    2015-04-01

    Secondary organic aerosol (SOA) have an important impact on climate, air quality and human health. However the chemical reactions involved in their formation and growth are not fully understood or well-constrained in climate models. It is well known that inorganic sulfur (mainly in oxidation states (+IV) and (+VI)) plays a key role in aerosol formation, for instance sulfuric acid is known to be a good nucleating gas. In addition, acid-catalyzed heterogeneous reactions of organic compounds has shown to produce new particles, with a clear enhancement in the presence of ozone (Iinuma 2013). Organosulfates have been detected in tropospheric particles and aqueous phases, which suggests they are products of secondary organic aerosol formation process (Tolocka 2012). Originally, the production of organosulfates was explained by the esterification reaction of alcohols, but this reaction in atmosphere is kinetically negligible. Other formation pathways have been suggested such as hydrolysis of peroxides and reaction of organic matter with sulfite and sulfate radical anions (SO3-, SO4-) (Nozière 2010), but it remains unclear if these can completely explain atmospheric organo-sulfur aerosol loading. To better understand the formation of organo-sulfur compounds, we started to investigate the reactivity of SIV species (SO2 and SO32-) with respect to specific functional groups (organic acids and double bonds) on atmospherically relevant carboxylic acids and alkenes. The experiments were carried out in the homogeneous aqueous phase and at the solid-gas interface. A custom built coated-wall flow tube reactor was developed to control relativity humidity, SO2 concentration, temperature and gas flow rate. Homogeneous and heterogeneous reaction kinetics were measured and resulting products were identified using liquid chromatography coupled with an orbitrap mass spectrometer (LC-HR-MS). The experiments were performed with and without the presence of ozone in order to evaluate any

  13. Molecular weight growth in Titan's atmosphere: branching pathways for the reaction of 1-propynyl radical (H3CC≡C˙) with small alkenes and alkynes.

    PubMed

    Kirk, Benjamin B; Savee, John D; Trevitt, Adam J; Osborn, David L; Wilson, Kevin R

    2015-08-28

    The reaction of small hydrocarbon radicals (i.e.˙CN, ˙C2H) with trace alkenes and alkynes is believed to play an important role in molecular weight growth and ultimately the formation of Titan's characteristic haze. Current photochemical models of Titan's atmosphere largely assume hydrogen atom abstraction or unimolecular hydrogen elimination reactions dominate the mechanism, in contrast to recent experiments that reveal significant alkyl radical loss pathways during reaction of ethynyl radical (˙C2H) with alkenes and alkynes. In this study, the trend is explored for the case of a larger ethynyl radical analogue, the 1-propynyl radical (H3CC[triple bond, length as m-dash]C˙), a likely product from the high-energy photolysis of propyne in Titan's atmosphere. Using synchrotron vacuum ultraviolet photoionization mass spectrometry, product branching ratios are measured for the reactions of 1-propynyl radical with a suite of small alkenes (ethylene and propene) and alkynes (acetylene and d4-propyne) at 4 Torr and 300 K. Reactions of 1-propynyl radical with acetylene and ethylene form single products, identified as penta-1,3-diyne and pent-1-en-3-yne, respectively. These products form by hydrogen atom loss from the radical-adduct intermediates. The reactions of 1-propynyl radical with d4-propyne and propene form products from both hydrogen atom and methyl loss, (-H = 27%, -CH3 = 73%) and (-H = 14%, -CH3 = 86%), respectively. Together, these results indicate that reactions of ethynyl radical analogues with alkenes and alkynes form significant quantities of products by alkyl loss channels, suggesting that current photochemical models of Titan over predict both hydrogen atom production as well as the efficiency of molecular weight growth in these reactions. PMID:26204935

  14. Atmospheric Reaction Systems as Null-Models to Identify Structural Traces of Evolution in Metabolism

    PubMed Central

    Holme, Petter; Huss, Mikael; Lee, Sang Hoon

    2011-01-01

    The metabolism is the motor behind the biological complexity of an organism. One problem of characterizing its large-scale structure is that it is hard to know what to compare it to. All chemical reaction systems are shaped by the same physics that gives molecules their stability and affinity to react. These fundamental factors cannot be captured by standard null-models based on randomization. The unique property of organismal metabolism is that it is controlled, to some extent, by an enzymatic machinery that is subject to evolution. In this paper, we explore the possibility that reaction systems of planetary atmospheres can serve as a null-model against which we can define metabolic structure and trace the influence of evolution. We find that the two types of data can be distinguished by their respective degree distributions. This is especially clear when looking at the degree distribution of the reaction network (of reaction connected to each other if they involve the same molecular species). For the Earth's atmospheric network and the human metabolic network, we look into more detail for an underlying explanation of this deviation. However, we cannot pinpoint a single cause of the difference, rather there are several concurrent factors. By examining quantities relating to the modular-functional organization of the metabolism, we confirm that metabolic networks have a more complex modular organization than the atmospheric networks, but not much more. We interpret the more variegated modular arrangement of metabolism as a trace of evolved functionality. On the other hand, it is quite remarkable how similar the structures of these two types of networks are, which emphasizes that the constraints from the chemical properties of the molecules has a larger influence in shaping the reaction system than does natural selection. PMID:21573072

  15. Adsorption and reactions of atmospheric constituents and pollutants on ice particles: an FTIR study

    NASA Astrophysics Data System (ADS)

    Rudakova, A. V.; Marinov, I. L.; Poretskiy, M. S.; Tsyganenko, A. A.

    2009-04-01

    , which act as adsorption sites either as a proton-donor or as a donor of the lone pair of electrons. Such adsorption-induced relaxation explains the dependence of physico-chemical properties of icy particles on the presence of atmospheric gases. Spectra HCN/D2O and ND3/D2O mixed icy films with low (1:10) dopant/water ratios do not manifest any changes in the acidic or basic properties of dangling hydroxyl groups or surface oxygen atoms, but reveal a difference in the proportion between the concentrations of these sites as compared with that for pure water ice. For high dopant concentrations (1:1), the dangling hydroxyls were not observed; the dominant adsorption sites for CO are likely to be the unsaturated oxygen atoms, while serious structural changes occur in the bulk of ices. Ecologically important reactions of atmospheric pollutants such as ozonolysis of ethene, chlorinated ethenes, hydrogen cyanide, and methyl bromide adsorbed on water ice film as well as the influence of UV radiation on this process have been studied in 77 - 200 K temperature range by FTIR spectroscopy. Ozone co-adsorption with ethene or C2H3Cl readily leads to ozonolysis reaction, which also starts for C2H2Cl2 isomers but only at temperatures elevated up to 120 - 150 K. Co-adsorption of O3 with HCN or CH3Br molecules in the dark does not lead to any noticeable spectral changes. Irradiation of HCN or CH3Br deposited on ice films in the presence of ozone leads to appearance of new bands revealing the formation of ozonolysis products. The same "synergetic effect" of simultaneous action of ozone and UV radiation at 77 K, was found for C2H2Cl2 isomers and C2Cl4, which are resistant against O3 even at higher temperatures. The obtained spectral dependence of photo-ozonolysis of C2Cl4 and HCN at 77 K shows that photoexcitation or photodissociation of ozone, evidently, accounts for the observed processes. The surface of ice particles, thus, plays the role of a condenser of atmospheric pollutants and acts

  16. Computational studies of atmospherically-relevant chemical reactions in water clusters and on liquid water and ice surfaces.

    PubMed

    Gerber, R Benny; Varner, Mychel E; Hammerich, Audrey D; Riikonen, Sampsa; Murdachaew, Garold; Shemesh, Dorit; Finlayson-Pitts, Barbara J

    2015-02-17

    CONSPECTUS: Reactions on water and ice surfaces and in other aqueous media are ubiquitous in the atmosphere, but the microscopic mechanisms of most of these processes are as yet unknown. This Account examines recent progress in atomistic simulations of such reactions and the insights provided into mechanisms and interpretation of experiments. Illustrative examples are discussed. The main computational approaches employed are classical trajectory simulations using interaction potentials derived from quantum chemical methods. This comprises both ab initio molecular dynamics (AIMD) and semiempirical molecular dynamics (SEMD), the latter referring to semiempirical quantum chemical methods. Presented examples are as follows: (i) Reaction of the (NO(+))(NO3(-)) ion pair with a water cluster to produce the atmospherically important HONO and HNO3. The simulations show that a cluster with four water molecules describes the reaction. This provides a hydrogen-bonding network supporting the transition state. The reaction is triggered by thermal structural fluctuations, and ultrafast changes in atomic partial charges play a key role. This is an example where a reaction in a small cluster can provide a model for a corresponding bulk process. The results support the proposed mechanism for production of HONO by hydrolysis of NO2 (N2O4). (ii) The reactions of gaseous HCl with N2O4 and N2O5 on liquid water surfaces. Ionization of HCl at the water/air interface is followed by nucleophilic attack of Cl(-) on N2O4 or N2O5. Both reactions proceed by an SN2 mechanism. The products are ClNO and ClNO2, precursors of atmospheric atomic chlorine. Because this mechanism cannot result from a cluster too small for HCl ionization, an extended water film model was simulated. The results explain ClNO formation experiments. Predicted ClNO2 formation is less efficient. (iii) Ionization of acids at ice surfaces. No ionization is found on ideal crystalline surfaces, but the process is efficient on

  17. Compression of Martian atmosphere for production of oxygen

    NASA Technical Reports Server (NTRS)

    Lynch, D. C.; Cutler, A. H.; Nolan, P. E.

    1991-01-01

    The compression of CO2 from the Martian atmosphere for production of O2 via an electrochemical cell is addressed. Design specifications call for an oxygen production rate of 10 kg per day and for compression of 50 times that mass of CO2. Those specifications require a compression rate of over 770 cfm at standard Martian temperature and pressure (SMTP). Much of the CO2 being compressed represents waste, unless it can be recycled. Recycling can reduce the volume of gas that must be compressed to 40 cfm at SMTP. That volume reduction represents significant mass savings in the compressor, heating equipment, filters, and energy source. Successful recycle of the gas requires separation of CO (produced in the electrochemical cell) from CO2, N2, and Ar found in the Martian atmosphere. That aspect was the focus of this work.

  18. Effect of atmospheric oxidative plasma treatments on polypropylenic fibers surface: Characterization and reaction mechanisms

    NASA Astrophysics Data System (ADS)

    Nisticò, Roberto; Magnacca, Giuliana; Faga, Maria Giulia; Gautier, Giovanna; D'Angelo, Domenico; Ciancio, Emanuele; Lamberti, Roberta; Martorana, Selanna

    2013-08-01

    Atmospheric pressure plasma-dielectric barrier discharge (APP-DBD, open chamber configuration) was used to functionalize polypropylene (PP) fibers surface in order to generate oxidized-reactive groups such as hydroperoxides, alcohols and carbonyl species (i.e. ketones and others). Such a species increased the surface polarity, without causing material degradation. Three different types of plasma mixture (He, He/O2, He/O2/H2O) under three different values of applied power (750, 1050, 1400 W) were investigated. The formed plasma species (O2+, O single atom and OH radical) and their distribution were monitored via optical emission spectrometry (OES) measurements, and the plasma effects on PP surface species formation were followed by X-ray photoemission spectroscopy (XPS). Results allowed to better understand the reaction pathways between plasma phase and PP fibers. In fact, two reaction mechanisms were proposed, the first one concerning the plasma phase reactions and the second one involving material surface modifications.

  19. Thermal and photochemical reactions of NO2 on chromium(III) oxide surfaces at atmospheric pressure.

    PubMed

    Nishino, Noriko; Finlayson-Pitts, Barbara J

    2012-12-01

    While many studies of heterogeneous chemistry on Cr(2)O(3) surfaces have focused on its catalytic activity, less is known about chemistry on this surface under atmospheric conditions. We report here studies of the thermal and photochemical reactions of NO(2) on Cr(2)O(3) at one atm in air. In order to follow surface species, the interaction of 16-120 ppm NO(2) with a 15 nm Cr(2)O(3) thin film deposited on a germanium crystal was monitored in a flow system using attenuated total reflectance (ATR) coupled to a Fourier transform infrared (FTIR) spectrometer. Gas phase products were monitored in the effluent of an ~285 ppm NO(2)-air mixture that had passed over Cr(2)O(3) powder in a flow system. A chemiluminescence NO(y) analyzer, a photometric O(3) analyzer and a long-path FTIR spectrometer were used to probe the gaseous products. In the absence of added water vapor, NO(2) formed nitrate (NO(3)(-)) ions coordinated to Cr(3+). These surface coordinated NO(3)(-) were reversibly solvated by water under humid conditions. In both dry and humid cases, nitrate ions decreased during irradiation of the surface at 302 nm, and NO and NO(2) were generated in the gas phase. Under dry conditions, NO was the major gaseous product while NO(2) was the dominant species in the presence of water vapor. Heating of the surface after exposure to NO(2) led to the generation of both NO(2) and NO under dry conditions, but only NO(2) in the presence of water vapor. Elemental chromium incorporated into metal alloys such as stainless steel is readily oxidized in contact with ambient air, forming a chromium-rich metal oxide surface layer. The results of these studies suggest that active photo- and thermal chemistry will occur when boundary layer materials containing chromium(III) or chromium oxide such as stainless steel, roofs, automobile bumpers etc. are exposed to NO(2) under tropospheric conditions. PMID:23090708

  20. Studies in photochemical smog chemistry. I. Atmospheric chemistry of toluene. II. Analysis of chemical reaction mechanisms for photochemical smog

    SciTech Connect

    Leone, J.A.

    1985-01-01

    This study focuses on two related topics in the gas phase organic chemistry of importance in urban air pollution. Part I describes an experimental and modeling effort aimed at developing a new explicit reaction mechanism for the atmospheric photooxidation of toluene. This mechanism is tested using experimental data from both indoor and outdoor smog chamber facilities. The predictions of the new reaction mechanism are found to be in good agreement with both sets of experimental data. Additional simulations performed with the new mechanism are used to investigate various mechanistic paths, and to gain insight into areas where the understanding is not complete. The outdoor experimental facility, which was built to provide the second set of experimental data, consists of a 65 cubic meter teflon smog chamber together with full instrumentation capable of measuring ozone, nitrogen dioxide, nitric oxide, peroxyacetyl nitrate (PAN), carbon monoxide, relative humidity, temperature, aerosol size distributions, and of course toluene and its photooxidation products. In Part II, a theoretical analysis of lumped chemical reaction mechanisms for photochemical smog is presented. Included is a description of a new counter species analysis technique which can be used to analyze any complex chemical reaction mechanism. Finally, a new lumped mechanism for photochemical smog is developed and tested against experimental data from two smog chamber facilities. Advantages of this mechanism relative to the existing lumped mechanisms are discussed.

  1. Kinetics and Product Yields of the Gas-Phase Reactions of Isoprene Hydroxynitrates and Isoprene Carbonynitrates

    NASA Astrophysics Data System (ADS)

    Abdelhamid, A.; Addala, R.; Vizenor, N.; Scruggs, A.; Tyndall, G. S.; Orlando, J. J.; Le, T.; Cardenas, E.; Maitra, S.; Hasson, A. S.

    2013-12-01

    Isoprene nitrates are formed in the troposphere from the reactions of isoprene with OH in the presence of NOx during the day and with NO3 during the night. Depending on their subsequent reactions, these compounds may be reservoirs or sinks for NOx, and may contribute to secondary organic aerosol formation. In this work, two isoprene hydroxynitrates (CH2=CHC(ONO2)(CH3)CH2OH, 1,2-IHN and CH2OHCH(ONO2)C(CH3)=CH2, 4,3-IHN ) and one isoprene carbonyl nitrate (CH2=CHC(ONO2)(CH3)CHO, ICN)) were synthesized. The kinetics and product yields from their reaction with O3, OH, NO3 and Cl were then investigated in a photochemical reactor using a combination of long-path Fourier transform infra-red spectroscopy, proton transfer reaction mass spectrometry and gas chromatography with flame ionization detection. Measured rate coefficients are consistent with reaction with OH and NO3 as the major chemical sinks for these compounds. Measured product yields imply that NOx is not released from these compounds in their reactions with atmospheric oxidants.

  2. Synthesis of superheavy nuclei: A search for new production reactions

    SciTech Connect

    Zagrebaev, Valery; Greiner, Walter

    2008-09-15

    Nuclear reactions leading to the formation of new superheavy (SH) elements and isotopes are discussed in the paper. 'Cold' and 'hot' synthesis, fusion of fission fragments, transfer reactions, and reactions with radioactive ion beams are analyzed along with their abilities and limitations. If the possibility of increasing the beam intensity and the detection efficiency (by a total of one order of magnitude) is found, then several isotopes of new elements with Z=120-124 could be synthesized in fusion reactions of titanium, chromium, and iron beams with actinide targets. The use of light- and medium-mass neutron-rich radioactive beams may help us fill the gap between the SH nuclei produced in the hot fusion reactions and the mainland. In these reactions, we may really approach the 'island of stability.' Such a possibility is also provided by the multinucleon transfer processes in low-energy damped collisions of heavy actinide nuclei. The production of SH elements in fusion reactions with accelerated fission fragments looks less encouraging.

  3. Particulate and gas-phase products from the atmospheric degradation of chlorpyrifos and chlorpyrifos-oxon

    NASA Astrophysics Data System (ADS)

    Borrás, Esther; Ródenas, Milagros; Vázquez, Mónica; Vera, Teresa; Muñoz, Amalia

    2015-12-01

    The phosphorothioate structure is highly present in several pesticides. However, there is a lack of information about its degradation process in air and the secondary pollutants formed. Herein, the atmospheric reactions of chlorpyrifos, one of the most world-used insecticide, and its main degradation product - chlorpyrifos-oxon - are described. The photo-oxidation under the presence of NOx was studied in a large outdoor simulation chamber for both chlorpyrifos and chlorpyrifos-oxon, observing a rapid degradation (Half lifetime < 3.5 h for both compounds). Also, the photolysis reactions of both were studied. The formation of particulate matter (aerosol mass yield ranged 6-59%) and gaseous products were monitored. The chemical composition of minor products was studied, identifying 15 multi-oxygenated derivatives. The most abundant products were ring-retaining molecules such as 3,5,6-trichloropyridin-2-ol and ethyl 3,5,6-trichloropyridin-2-yl hydrogen phosphate. An atmospheric degradation mechanism has been amplified based on an oxidation started with OH-nucleophilic attack to Pdbnd S bond.

  4. Fission-product SiC reaction in HTGR fuel

    SciTech Connect

    Montgomery, F.

    1981-07-13

    The primary barrier to release of fission product from any of the fuel types into the primary circuit of the HTGR are the coatings on the fuel particles. Both pyrolytic carbon and silicon carbide coatings are very effective in retaining fission gases under normal operating conditions. One of the possible performance limitations which has been observed in irradiation tests of TRISO fuel is chemical interaction of the SiC layer with fission products. This reaction reduces the thickness of the SiC layer in TRISO particles and can lead to release of fission products from the particles if the SiC layer is completely penetrated. The experimental section of this report describes the results of work at General Atomic concerning the reaction of fission products with silicon carbide. The discussion section describes data obtained by various laboratories and includes (1) a description of the fission products which have been found to react with SiC; (2) a description of the kinetics of silicon carbide thinning caused by fission product reaction during out-of-pile thermal gradient heating and the application of these kinetics to in-pile irradiation; and (3) a comparison of silicon carbide thinning in LEU and HEU fuels.

  5. CHLORINE DIOXIDE CHEMISTRY, REACTIONS, AND DISINFECTION BY-PRODUCTS

    EPA Science Inventory

    This chapter contains two main sections-the first section describes the chemistry and reactions of chlorine dioxide, and the second describes the disinfection by-products (DBPs) of chlorine dioxide and their control. A short section on Research Needs completes this chapter. The...

  6. Energy distribution among reaction products. VII - H + F2.

    NASA Technical Reports Server (NTRS)

    Polanyi, J. C.; Sloan, J. J.

    1972-01-01

    The 'arrested relaxation' variant of the IR chemiluminescence technique is used in a study of the distribution of vibrational, rotational and translational energies between the products of the reaction by which H + F2 yields HF + F. Diagrams are plotted and numerical values are obtained for the energy distribution rate constants.

  7. Modeling of atmospheric OH reaction rates using newly developed variable distance weighted zero order connectivity index

    NASA Astrophysics Data System (ADS)

    Markelj, Jernej; Pompe, Matevž

    2016-04-01

    A new variable distance weighted zero order connectivity index was used for development of structure-activity relationship for modeling reactivity of OH radical with alkanes and non-conjugated alkenes in the atmosphere. The proposed model is based on the assumptions that the total reaction rate can be obtained by summing all partial reaction rates and that all reaction sites are interrelated by influencing each other. The results suggest that these assumptions are justified. The model was compared with the EPA implemented model in the studied application domain and showed superior prediction capabilities. Further, optimized values of the weights that were used in our model permit some insight into mechanisms that govern the reaction OH + alkane/alkene. The most important conclusion is that the branching degree of the forming radical seems to play a major role in site specific reaction rates. Relative qualitative structural interpretation is possible, e.g. allylic site is suggested to be much more reactive than even tertiary sp3 carbon. Novel modeling software MACI, which was developed in our lab and is now available for research purposes, was used for calculations. Various variable topological indices that are again starting to be recognized because of their great potentials in simplicity, fast calculations, very good correlations and structural information, were implemented in the program.

  8. Gas-Phase Reactions of Methoxyphenols with NO3 Radicals: Kinetics, Products, and Mechanisms.

    PubMed

    Zhang, Haixu; Yang, Bo; Wang, Youfeng; Shu, Jinian; Zhang, Peng; Ma, Pengkun; Li, Zhen

    2016-03-01

    Methoxyphenols, a group of important tracers for wood smoke, are emitted to the atmosphere in large quantities, but their transformations are rarely studied. In this study, the kinetics and products of the gas-phase reactions of eugenol and 4-ethylguaiacol with NO3 radicals were investigated online using a vacuum ultraviolet photoionization gas time-of-flight mass spectrometer. The rate coefficients of the gaseous reactions of eugenol and 4-ethylguaiacol with NO3 radicals were (1.6 ± 0.4) × 10(-13) and (1.1 ± 0.2) × 10(-12) cm(3) molecule(-1) s(-1) (at 298 K), indicating that the atmospheric lifetimes of the NO3 radicals were 3.5 and 0.5 h, respectively. With the aid of gas-chromatography-mass-spectrometry analysis, several types of degradation products were identified with nitro derivatives as the major products. The configurations of the nitro-product isomers and their formation mechanisms were determined via theoretical calculations. On the basis of these products, degradation pathways of the methoxyphenols with NO3 radicals were proposed. This study determines the degradation rates and mechanisms of the methoxyphenols at night and implies the significant NO3 nighttime chemistry. PMID:26845070

  9. THE GAS PHASE REACTION OF OZONE WITH 1,3-BUTADIENE: FORMATION YIELDS OF SOME TOXIC PRODUCTS. (R826236)

    EPA Science Inventory

    The formation yields of acrolein, 1,2-epoxy-3-butene and OH radicals have been measured from reaction of ozone with 1,3-butadiene at room temperature and atmosphere pressure. 1,3,5-Trimethyl benzene was added to scavenge OH radicals in measurements of product yields. In separa...

  10. Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection.

    PubMed

    Trevitt, Adam J; Goulay, Fabien

    2016-02-17

    For reactive gas-phase environments, including combustion, extraterrestrials atmospheres and our Earth's atmosphere, the availability of quality chemical data is essential for predictive chemical models. These data include reaction rate coefficients and product branching fractions. This perspective overviews recent isomer-resolved production detection experiments for reactions of two of the most reactive gas phase radicals, the CN and CH radicals, with a suite of small hydrocarbons. A particular focus is given to flow-tube experiments using synchrotron photoionization mass spectrometry. Coupled with computational studies and other experiment techniques, flow tube isomer-resolved product detection have provided significant mechanistic details of these radical + neutral reactions with some general patterns emerging. PMID:26841339

  11. Methyl chavicol: characterization of its biogenic emission rate, abundance, and oxidation products in the atmosphere

    NASA Astrophysics Data System (ADS)

    Bouvier-Brown, N. C.; Goldstein, A. H.; Worton, D. R.; Matross, D. M.; Gilman, J. B.; Kuster, W. C.; Welsh-Bon, D.; Warneke, C.; de Gouw, J. A.; Cahill, T. M.; Holzinger, R.

    2009-03-01

    We report measurements of ambient atmospheric mixing ratios for methyl chavicol and determine its biogenic emission rate. Methyl chavicol, a biogenic oxygenated aromatic compound, is abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol was detected simultaneously by three in-situ instruments - a gas chromatograph with mass spectrometer detector (GC-MS), a proton transfer reaction mass spectrometer (PTR-MS), and a thermal desorption aerosol GC-MS (TAG) - and found to be abundant within and above Blodgett Forest. Methyl chavicol atmospheric mixing ratios are strongly correlated with 2-methyl-3-buten-2-ol (MBO), a light- and temperature-dependent biogenic emission from the ponderosa pine trees at Blodgett Forest. Scaling from this correlation, methyl chavicol emissions account for 4-68% of the carbon mass emitted as MBO in the daytime, depending on the season. From this relationship, we estimate a daytime basal emission rate of 0.72-10.2 μgCg-1 h-1, depending on needle age and seasonality. We also present the first observations of its oxidation products (4-methoxybenzaldehyde and 4-methyoxy benzene acetaldehyde) in the ambient atmosphere. Methyl chavicol is a major essential oil component of many plant species. This work suggests that methyl chavicol plays a significant role in the atmospheric chemistry of Blodgett Forest, and potentially other sites, and should be included explicitly in both biogenic volatile organic carbon emission and atmospheric chemistry models.

  12. Radical product yields from the ozonolysis of short chain alkenes under atmospheric boundary layer conditions.

    PubMed

    Alam, Mohammed S; Rickard, Andrew R; Camredon, Marie; Wyche, Kevin P; Carr, Timo; Hornsby, Karen E; Monks, Paul S; Bloss, William J

    2013-11-27

    The gas-phase reaction of ozone with unsaturated volatile organic compounds (VOCs), alkenes, is an important source of the critical atmospheric oxidant OH, especially at night when other photolytic radical initiation routes cannot occur. Alkene ozonolysis is also known to directly form HO2 radicals, which may be readily converted to OH through reaction with NO, but whose formation is poorly understood. We report a study of the radical (OH, HO2, and RO2) production from a series of small alkenes (propene, 1-butene, cis-2-butene, trans-2-butene, 2-methylpropene, 2,3-dimethyl-2-butene (tetramethyl ethene, TME), and isoprene). Experiments were performed in the European Photoreactor (EUPHORE) atmospheric simulation chamber, with OH and HO2 levels directly measured by laser-induced fluorescence (LIF) and HO2 + ΣRO2 levels measured by peroxy-radical chemical amplification (PERCA). OH yields were found to be in good agreement with the majority of previous studies performed under comparable conditions (atmospheric pressure, long time scales) using tracer and scavenger approaches. HO2 yields ranged from 4% (trans-2-butene) to 34% (2-methylpropene), lower than previous experimental determinations. Increasing humidity further reduced the HO2 yields obtained, by typically 50% for an RH increase from 0.5 to 30%, suggesting that HOx production from alkene ozonolysis may be lower than current models suggest under (humid) ambient atmospheric boundary layer conditions. The mechanistic origin of the OH and HO2 production observed is discussed in the context of previous experimental and theoretical studies. PMID:24171583

  13. Ir Spectroscopy of Selected Atmospheric Monoterpenes and Oxydation Products

    NASA Astrophysics Data System (ADS)

    Aviles Moreno, Juan-Ramon; Huet, T. R.; Goubet, Manuel; Soulard, Pascale; Asselin, Pierre; Georges, Robert; Pirali, Olivier; Roy, P.

    2014-06-01

    Several monoterpenes are biogenic volatile organic compounds (BVOCS) present in the atmosphere. They can react with OH, O_3, NO_x, etc. to give rise to several oxydation and degradation products. We have studied the gas phase spectroscopy of monocyclic (limonene, γ-terpinene) and bicyclic (α-pinene, β-pinene) atmospheric monoterpenes (C10H_{16}), as well as two C10H_{14O} oxydation products (perillaldehyde, carvone). In the first step of this work, theoretical calculations and microwave spectroscopy were used in order to evidence the most stable conformers and their relative energies. In the present communication we will present the results of the IR study. Infrared spectra have been recorded on the FTIR spectrometer of the AILES beamline at synchrotron SOLEIL, using the Jet-AILES molecular beam and a long path cell. Special attention was given to the 700-1300 wn atmospheric window, to the CH vibration region, and to the "finger print" FIR region. Quantum calculations have been performed at different levels of theory (DFT, ab initio). In particular anharmonic force fields were obtained in order to model the vibrational structures. J. R. Aviles Moreno, F. Partal Urena, J. J. Lopez Gonzalez and T. R. Huet, C. Phys. Lett. 473 (2009) 17 J. R. Aviles Moreno, T. R. Huet, F. Partal Urena, J. J. Lopez Gonzalez, Struc. Chem. 24 (2013) 1163 J. R. Aviles Moreno, E. Neeman, T. R. Huet, manuscript in preparation Support from the French Laboratoire d'Excellence CaPPA (Chemical and Physical Properties of the Atmosphere) through contract ANR-10-LABX-0005 of the Programme d'Investissements d'Avenir is acknowledged. The experiment on the AILES beam-line at synchrotron SOLEIL was performed under project number 20130192.

  14. Products and kinetics of the heterogeneous reaction of particulate ametryn with NO3 radicals.

    PubMed

    Liu, Chang-Geng; Shu, Ji-Nian; Yang, Bo; Zhang, Peng

    2014-12-01

    As a renowned s-triazine herbicide, ametryn is worldwide emitted into the atmosphere in both gaseous and particulate phases via spray drifts from treatments and post application emissions, but its chemical degradation in the atmosphere has not been well characterized. In this study, the heterogeneous kinetics of particulate ametryn with NO3 radicals were investigated with a mixed-phase relative rate method. A vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and an atmospheric gas analysis mass spectrometer were synchronously used to online monitor the decays of particulate ametryn and gas-phase isoprene. The reactive uptake coefficient of NO3 radicals on ametryn particles was calculated to be 2.9 × 10(-2), according to the measured ametryn loss ratio and the average NO3 concentration. The effective rate constant for the heterogeneous reaction of particulate ametryn with NO3 radicals measured under experimental conditions was 8.4 × 10(-13) cm(3) molecule(-1) s(-1). In addition, atraton, ametryn sulfoxide and ametryn sulfone were identified as the reaction products by gas-chromatography-mass spectrometry (GC-MS) analysis. The experimental results might shed light on the chemical behavior of atmospheric ametryn at night-time. PMID:25301341

  15. Clocking Surface Reaction by In-Plane Product Rotation.

    PubMed

    Anggara, Kelvin; Huang, Kai; Leung, Lydie; Chatterjee, Avisek; Cheng, Fang; Polanyi, John C

    2016-06-15

    Electron-induced reaction of physisorbed meta-diiodobenzene (mDIB) on Cu(110) at 4.6 K was studied by Scanning Tunneling Microscopy and molecular dynamics theory. Single-electron dissociation of the first C-I bond led to in-plane rotation of an iodophenyl (IPh) intermediate, whose motion could be treated as a "clock" of the reaction dynamics. Alternative reaction mechanisms, successive and concerted, were observed giving different product distributions. In the successive mechanism, two electrons successively broke single C-I bonds; the first C-I bond breaking yielded IPh that rotated directionally by three different angles, with the second C-I bond breaking giving chemisorbed I atoms (#2) at three preferred locations corresponding to the C-I bond alignments in the prior rotated IPh configurations. In the concerted mechanism a single electron broke two C-I bonds, giving two chemisorbed I atoms; significantly these were found at angles corresponding to the C-I bond direction for unrotated mDIB. Molecular dynamics accounted for the difference in reaction outcomes between the successive and the concerted mechanisms in terms of the time required for the IPh to rotate in-plane; in successive reaction the time delay between first and second C-I bond-breaking events allowed the IPh to rotate, whereas in concerted reaction the computed delay between excitation and reaction (∼1 ps) was too short for molecular rotation before the second C-I bond broke. The dependence of the extent of motion at a surface on the delay between first and second bond breaking suggested a novel means to "clock" sub-picosecond dynamics by imaging the products arising from varying time delays between impacting pairs of electrons. PMID:27191189

  16. Interplay between Diffusion, Accretion and Nuclear Reactions in the Atmospheres of Sirius and Przybylski's Star

    NASA Astrophysics Data System (ADS)

    Yushchenko, A.; Gopka, V.; Goriely, S.; Lambert, D.; Shavrina, A.; Kang, Y. W.; Rostopchin, S.; Valyavin, G.; Lee, B.-C.; Kim, C.

    2007-06-01

    The abundance anomalies in chemically peculiar B-F stars are usually explained by diffusion of chemical elements in the stable atmospheres of these stars. But it is well known that peculiar stars with similar temperatures and gravities show very different chemical compositions. We show that the abundance patterns of several stars can be influenced by accretion and (or) nuclear reactions in stellar atmospheres. The first case is one of the hottest Am stars - Sirius. We determined the abundances of more than 50 chemical elements in the atmosphere of Sirius A and show that Sirius A was contaminated by s-process enriched matter from Sirius B (now a white dwarf). The second case is the well known Przybylski's star. The abundance pattern of this star is the second most studied one after the Sun with abundances determined for about 60 chemical elements. Spectral lines of radioactive elements with short decay times were found in the spectrum of this star. We report the results of our investigation on the stratification of chemical elements in the atmosphere of Przybylski's star and the new identification of lines corresponding to short-lived actinides in its spectrum. Possible explanations of the abundances pattern of Przybylski's star (as well as HR465 and HD965) can be the natural radioactive decays of thorium and uranium, the explosion of a companion as a supernova or the spallation reactions. These three hypotheses and (or) diffusion can possibly explain the abundance pattern of Przybylski's star and several similar objects such as HR465 and HD965.

  17. Competing reactions of selected atmospheric gases on Fe3O4 nanoparticles surfaces.

    PubMed

    Eltouny, N; Ariya, Parisa A

    2014-11-14

    Heterogeneous reactions on atmospheric aerosol surfaces are increasingly considered important in understanding aerosol-cloud nucleation and climate change. To understand potential reactions in polluted atmospheres, the co-adsorption of NO2 and toluene to magnetite (Fe3O4i.e. FeO·Fe2O3) nanoparticles at ambient conditions was investigated for the first time. The surface area, size distribution, and morphology of Fe3O4 nanoparticles were characterized by BET method and high-resolution transmission electron microscopy. Adsorption isotherms, collected by gas chromatography with flame ionization detection, showed that the presence of NO2 decreased the adsorption of toluene. The analyses of the surface chemical composition of Fe3O4 by X-ray photoelectron spectroscopy (XPS) reveal that, upon the addition of NO2, the surface is oxidized and a contribution at 532.5 ± 0.4 eV in the O1s spectrum appears, showing that NO2 likely competes with toluene by dissociating on Fe(2+) sites and forming NO3(-). Different competing effects were observed for oxidized Fe3O4; oxidation occurred when exposed solely to NO2, whereas, the mixture of toluene and NO2 resulted in a reduction of the surface i.e. increased Fe(2+)/Fe(3+). Analyses by time of flight secondary ion mass spectrometry further suggest toluene reacts with Fe(3+) sites forming oxygenated organics. Our results indicate that on reduced magnetite, NO2 is more reactive and competes with toluene; in contrast, on oxidized Fe3O4, toluene is more reactive. Because magnetite can assume a range of oxidation ratios in the environment, different competing interactions between pollutants like NO2 and toluene could influence atmospheric processes, namely, the formation of Fe(2+) and the formation of atmospheric oxidants. PMID:25247461

  18. The Sentinel-4 Mission: Instrument Description and Atmospheric Composition Products

    NASA Astrophysics Data System (ADS)

    Veihelmann, Ben; Meijer, Yasjka; Ingmann, Paul; Koopman, Rob; Bazalgette Courrèges-Lacoste, Grégory; Stark, Hendrik

    2013-04-01

    The Sentinel-4 mission, together with Sentinel-5 and the Sentinel-5 Precursor missions, is part of the Global Monitoring for Environment and Security (GMES) space component covering the Earth's atmosphere. The primary objective of the Sentinel-4 mission is the observation of the diurnal cycle of tropospheric species in support of the air quality applications of GMES Atmosphere Services. The presentation focuses on the Sentinel-4/UVN instrument and its related Level-2 atmospheric composition products. The Sentinel-4 instrument is an Ultra-violet Visible Near infrared spectrometer (S4/UVN) which is embarked on the geostationary Meteosat Third Generation-Sounder (MTG-S) platforms. Key features of the S4/UVN instrument are the spectral range from 305 nm to 500 nm with a spectral resolution of 0.5 nm, and from 750 nm to 775 nm with a spectral resolution of 0.12 nm, in combination with a low polarization sensitivity and a high radiometric accuracy. The instrument shall observe Europe with a revisit time of one hour. The spatial sampling distance varies across the geographic coverage area and takes a value of 8 km at a reference location at 45˚ N. The expected launch date of the first MTG-S platform is 2019, and the expected lifetime is 15 years (two S4/UVN instruments in sequence on two MTG-S platforms). ESA will develop products based on the S4/UVN measurements for the key target species, which are NO2, O3, HCHO, SO2, aerosols, and CHOCHO, and for cloud and surface properties (mainly intermediate products). Also a synergetic O3 vertical profile product is foreseen based on observations from the S4/UVN and the MTG InfraRed Sounder (IRS) on-board the same platform. Synergetic aerosol and cloud products are foreseen based on observations from the S4/UVN and from the MTG Flexible Combined Imager (FCI) on-board the MTG-Imager (MTG-I) platform. Current pre-development studies are dedicated to a daily surface reflectance map product that treats the surface directionality as

  19. Metabolic transit and toxicity of Maillard reaction products.

    PubMed

    Finot, P A; Furniss, D E

    1989-01-01

    The feeding of Maillard reaction products (MRP) has been reported to lead to a variety of effects on metabolism which may be classed as "anti-nutritional" or "anti-physiological", depending on whether they are due to the loss of essential nutrients or to the presence of the MRP per se. This paper describes the sensitivity of essential nutrients in the "early" and "advanced" stages of the Maillard reaction, the metabolic transit of Amadori compounds, premelanoidins, melanoidins, hydroxymethyl-furfural, carboxymethyl-lysine, as well as the effects of MRP on pancreatic amylase and on urinary zinc excretion. PMID:2506565

  20. Sorption enhanced reaction process (SERP) for production of hydrogen

    SciTech Connect

    Sircar, S.; Anand, M.; Carvill, B.

    1995-09-01

    Sorption Enhanced Reaction (SER) is a novel process that is being developed for the production of lower cost hydrogen by steam-methane reforming (SMR). In this process, the reaction of methane with steam is carried out in the presence of an admixture of a catalyst and a selective adsorbent for carbon dioxide. The consequences of SER are: (1) reformation reaction at a significantly lower temperature (300-500{degrees}C) than conventional SMR (800-1100{degrees}C), while achieving the same conversion of methane to hydrogen, (2) the product hydrogen is obtained at reactor pressure (200-400 psig) and at 99+% purity directly from the reactor (compared to only 70-75% H{sub 2} from conventional SMR reactor), (3) downstream hydrogen purification step is either eliminated or significantly reduced in size. The early focus of the program will be on the identification of an adsorbent/chemisorbent for CO{sub 2} and on the demonstration of the SER concept for SMR in our state-of-the-art bench scale process. In the latter stages, a pilot plant will be built to scale-up the technology and to develop engineering data. The program has just been initiated and no significant results for SMR will be reported. However, results demonstrating the basic principles and process schemes of SER technology will be presented for reverse water gas shift reaction as the model reaction. If successful, this technology will be commercialized by Air Products and Chemicals, Inc. (APCI) and used in its existing hydrogen business. APCI is the world leader in merchant hydrogen production for a wide range of industrial applications.

  1. Photosensitized Production of Atmospherically Reactive Organic Compounds at the Air/Aqueous Interface.

    PubMed

    Fu, Hongbo; Ciuraru, Raluca; Dupart, Yoan; Passananti, Monica; Tinel, Liselotte; Rossignol, Stéphanie; Perrier, Sebastien; Donaldson, D James; Chen, Jianmin; George, Christian

    2015-07-01

    We report on experiments that probe photosensitized chemistry at the air/water interface, a region that does not just connect the two phases but displays its own specific chemistry. Here, we follow reactions of octanol, a proxy for environmentally relevant soluble surfactants, initiated by an attack by triplet-state carbonyl compounds, which are themselves concentrated at the interface by the presence of this surfactant. Gas-phase products are determined using PTR-ToF-MS, and those remaining in the organic layer are determined by ATR-FTIR spectroscopy and HPLC-HRMS. We observe the photosensitized production of carboxylic acids as well as unsaturated and branched-chain oxygenated products, compounds that act as organic aerosol precursors and had been thought to be produced solely by biological activity. A mechanism that is consistent with the observations is detailed here, and the energetics of several key reactions are calculated using quantum chemical methods. The results suggest that the concentrating nature of the interface leads to its being a favorable venue for radical reactions yielding complex and functionalized products that themselves could initiate further secondary chemistry and new particle formation in the atmospheric environment. PMID:26068588

  2. Photosensitized Production of Atmospherically Reactive Organic Compounds at the Air/Aqueous Interface

    PubMed Central

    2015-01-01

    We report on experiments that probe photosensitized chemistry at the air/water interface, a region that does not just connect the two phases but displays its own specific chemistry. Here, we follow reactions of octanol, a proxy for environmentally relevant soluble surfactants, initiated by an attack by triplet-state carbonyl compounds, which are themselves concentrated at the interface by the presence of this surfactant. Gas-phase products are determined using PTR-ToF-MS, and those remaining in the organic layer are determined by ATR-FTIR spectroscopy and HPLC-HRMS. We observe the photosensitized production of carboxylic acids as well as unsaturated and branched-chain oxygenated products, compounds that act as organic aerosol precursors and had been thought to be produced solely by biological activity. A mechanism that is consistent with the observations is detailed here, and the energetics of several key reactions are calculated using quantum chemical methods. The results suggest that the concentrating nature of the interface leads to its being a favorable venue for radical reactions yielding complex and functionalized products that themselves could initiate further secondary chemistry and new particle formation in the atmospheric environment. PMID:26068588

  3. Organic reactions increasing the absorption index of atmospheric sulfuric acid aerosols

    NASA Astrophysics Data System (ADS)

    Nozière, B.; Esteve, W.

    2005-02-01

    Unlike most environments present at Earth's surface atmospheric aerosols can be favorable to organic reactions. Among them, the acid-catalyzed aldol condensation of aldehydes and ketones produces light-absorbing compounds. In this work the increase of the absorption index of sulfuric acid solutions 50-96 wt. % resulting from the uptake of gas-phase acetaldehyde, acetone, and 2-butanone (methyl ethyl ketone), has been measured in the near UV and visible range. Our results indicate that the absorption index between 200 and 500 nm for stratospheric sulfuric aerosols exposed to 100 pptV of acetaldehyde (1 pptV = 10-12 v/v) would increase by four orders of magnitude over a two-year lifetime. Rough estimates based on previous radiative calculations suggest that this reaction could result in an increase of the radiative forcing of sulfate aerosols of the order of 0.01 W m-2, and that these processes are worth further investigation.

  4. The characterization of coal liquefaction products obtained under an inert atmosphere and catalytic conditions. Part II: Soluble products

    SciTech Connect

    Karaca, H.

    2006-03-15

    Beypazari and Tuncbilek lignite were liquefied using two different catalyst methods physically mixing and impregnation. The liquefaction occurred under conditions of inert atmosphere and various process parameters. Solvent to coal ratio, pressure, catalyst type, catalyst concentration, temperature, and time were examined as process parameters. The most appropriate parameters for the total soluble products obtained by liquefaction of both lignites and for elemental analysis of preasphaltenes were determined as follows: 2/1 solvent to coal ratio; from 1.25 MPa to 2.50 MPa initial nitrogen pressure; Fe{sub 2}O{sub 3} and Mo(CO){sub 6} as catalyst types; 3% as catalyst concentration; 400{sup o}C as reaction temperature; and 60 min as reaction time. In general, fuel quality of both preasphaltene and total soluble products decreased as temperature increased above 400{sup o}C and reaction time exceeded 60 min. The fuel quality of the preasphaltenes and the total soluble products obtained under the catalytic conditions and in the state of impregnation of catalyst onto coal is higher than under the noncatalytic conditions and in the state of physically mixing of catalyst.

  5. Gas Sensor Evaluations in Polymer Combustion Product Atmospheres

    NASA Technical Reports Server (NTRS)

    Delgado, Rafael H.; Davis, Dennis D.; Beeson, Harold D.

    1999-01-01

    Toxic gases produced by the combustion or thermo-oxidative degradation of materials such as wire insulation, foam, plastics, or electronic circuit boards in space shuttle or space station crew cabins may pose a significant hazard to the flight crew. Toxic gas sensors are routinely evaluated in pure gas standard mixtures, but the possible interferences from polymer combustion products are not routinely evaluated. The NASA White Sands Test Facility (WSTF) has developed a test system that provides atmospheres containing predetermined quantities of target gases combined with the coincidental combustion products of common spacecraft materials. The target gases are quantitated in real time by infrared (IR) spectroscopy and verified by grab samples. The sensor responses are recorded in real time and are compared to the IR and validation analyses. Target gases such as carbon monoxide, hydrogen cyanide, hydrogen chloride, and hydrogen fluoride can be generated by the combustion of poly(vinyl chloride), polyimide-fluoropolymer wire insulation, polyurethane foam, or electronic circuit board materials. The kinetics and product identifications for the combustion of the various materials were determined by thermogravimetric-IR spectroscopic studies. These data were then scaled to provide the required levels of target gases in the sensor evaluation system. Multisensor toxic gas monitors from two manufacturers were evaluated using this system. In general, the sensor responses satisfactorily tracked the real-time concentrations of toxic gases in a dynamic mixture. Interferences from a number of organic combustion products including acetaldehyde and bisphenol-A were minimal. Hydrogen bromide in the products of circuit board combustion registered as hydrogen chloride. The use of actual polymer combustion atmospheres for the evaluation of sensors can provide additional confidence in the reliability of the sensor response.

  6. Maillard reaction products from chitosan-xylan ionic liquid solution.

    PubMed

    Luo, Yuqiong; Ling, Yunzhi; Wang, Xiaoying; Han, Yang; Zeng, Xianjie; Sun, Runcang

    2013-10-15

    A facile method is reported to prepare Maillard reaction products (MRPs) from chitosan and xylan in co-solvent ionic liquid. UV absorbance and fluorescence changes were regarded as indicators of the occurrence of Maillard reaction. FT-IR, NMR, XRD and TG were used to investigate the structure of chitosan-xylan conjugate. The results revealed that when chitosan reacted with xylan in ionic liquid, the hydrogen bonds in chitosan were destroyed, the facts resulted in the formation of chitosan-xylan MRPs. Moreover, when the mass ratio of chitosan to xylan was 1:1, the Maillard reaction proceeded easily. In addition, relatively high antioxidant property was also noted for the chitosan-xylan conjugate with mass ratio 1:1. So the obtained chitosan-xylan MRP is a promising antioxidant agent for food industry. PMID:23987419

  7. Yields of O2(b 1 Sigma g +) from reactions of HO2. [in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Keyser, L. F.; Choo, K. Y.; Leu, M. T.

    1985-01-01

    The production of O2(b 1 Sigma g +) has been monitored for several reactions of the HO2 radical at 300 K using a discharge-flow apparatus with resonance fluorescence and chemiluminescence detection. In all cases, the resulting quantum efficiencies were found to be less than 0.03. O2(b) was observed when F atoms were added to H2O2 in the gas phase. The signal strengths of O2(b) were proportional to initial concentrations of HO2 formed by the F + H2O2 reaction. Observed /O2(b)/, /HO2/, and /OH/ vs /F/0 were analyzed using a simple three-step mechanism and a more complete computer simulation with 22 reaction steps. The results indicate that the F + HO2 reaction yields O2(b) with an efficiency of (3.6 + or - 1.4) x 10 to the -3rd. Yields from the O + OH2 reaction were less than 0.02, indicating that this reaction cannot be a major source of the O2(b) emission observed in the earth's nightglow.

  8. A Pilot Study of Ion - Molecule Reactions at Temperatures Relevant to the Atmosphere of Titan

    NASA Astrophysics Data System (ADS)

    Zymak, Illia; Žabka, Ján; Polášek, Miroslav; Španěl, Patrik; Smith, David

    2016-04-01

    Reliable theoretical models of the chemical kinetics of the ionosphere of Saturn's moon, Titan, is highly dependent on the precision of the rates of the reactions of ambient ions with hydrocarbon molecules at relevant temperatures. A Variable Temperature Selected Ions Flow Tube technique, which has been developed primarily to study these reactions at temperatures within the range of 200-330 K, is briefly described. The flow tube temperature regulation system and the thermalisation of ions are also discussed. Preliminary studies of two reactions have been carried out to check the reliability and efficacy of kinetics measurements: (i) Rate constants of the reaction of CH3 + ions with molecular oxygen were measured at different temperatures, which indicate values in agreement with previous ion cyclotron resonance measurements ostensibly made at 300 K. (ii) Formation of CH3 + ions in the reaction of N2 + ions with CH4 molecules were studied at temperatures within the range 240-310 K which showed a small but statistically significant decrease of the ratio of product CH3 + ions to reactant N2 + ions with reaction temperature.

  9. Reaction behavior of zircaloy with simulated fission products

    SciTech Connect

    Kohli, R.

    1981-01-01

    The investigation reported in this paper was prompted by the lack of information on the reaction behavior of Zircaloy on long-term exposure to fission product environments in the temperature range 573 - 973 K. Small Zircaloy-2 (Zircaloy-2 contains by weight 1.5% Sn; 0.15% Fe; 0.08% Cr; 0.05% Ni; rest Zr) strip specimens (ca. 25mm x 3mm x 0.75 mm thick) were exposed to various simulated fission product environments (Cs, I, Br, Cd, In, Sb, Sn, Se as vapor; all others as powders) for times to 5.4 Ms (1500 h) in the temperature range 673 - 973 K. The reaction behavior was characterized by scanning electron microscopy with an EDAX analyzer, optical metallography, and x-ray diffraction.

  10. Ion/molecule reaction and ion evaporation in atmospheric pressure spray ionization

    NASA Astrophysics Data System (ADS)

    Hirabayashi, Atsumu; Takada, Yasuaki; Kambara, Hideki; Umemura, Yuta; Ohta, Hitoshi; Ito, Haruhiko; Kuchitsu, Kozo

    1992-12-01

    The positive ions produced in atmospheric pressure spray ionization of ammonia, alanine and sucrose in aqueous solution were detected with a double-focusing mass spectrometer. The relative intensities of the quasi-molecular ions of ammonia, NH+4 (H2O)n (n = 0-3), were found to be proportional to the concentration of the ammonia solution and to increase with increasing distance d between the nozzle tip and the sample aperture of the mass spectrometer; this observation shows that the ammonia molecule is produced by the spray and is protonated at atmospheric pressure by a proton transfer reaction with the hydronium ion and its hydrated clusters. The observed dependences of the relative intensities of the protonated alanine molecules from alanine solution and the cationized sucrose molecules from sucrose solution on d show that some part of these quasi-molecular ions are also produced by the ion/molecule reaction in the gas phase. However, their dependences on the concentration, which are steeper than that in the ammonia case, indicate that a significant proportion of these ions are produced by ion evaporation from a droplet or liquid.

  11. Dual Position Sensitive MWPC for tracking reaction products at VAMOS++

    NASA Astrophysics Data System (ADS)

    Vandebrouck, M.; Lemasson, A.; Rejmund, M.; Fremont, G.; Pancin, J.; Navin, A.; Michelagnoli, C.; Goupil, J.; Spitaels, C.; Jacquot, B.

    2016-03-01

    The characteristics and performance of a Dual Position Sensitive Multi-Wire Proportional Counter (DPS-MWPC) used to measure the scattering angle, the interaction position on the target and the velocity of reaction products detected in the VAMOS++ magnetic spectrometer, are reported. The detector consists of a pair of position sensitive low pressure MWPCs and provides both fast timing signals, along with the two-dimensional position coordinates required to define the trajectory of the reaction products. A time-of-flight resolution of 305(11) ps (FWHM) was measured. The measured resolutions (FWHM) were 2.5(3) mrad and 560(70) μm for the scattering angle and the interaction point at the target respectively. The subsequent improvement of the Doppler correction of the energy of the γ-rays, detected in the γ-ray tracking array AGATA in coincidence with isotopically identified ions in VAMOS++, is also discussed.

  12. An impact-induced terrestrial atmosphere and iron-water reactions during accretion of the Earth

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1985-01-01

    Shock wave data and theoretical calculations were used to derive models of an impact-generated terrestrial atmosphere during accretion of the Earth. The models showed that impacts of infalling planetesimals not only provided the entire budget of terrestrial water but also led to a continuous depletion of near-surface layers of water-bearing minerals of their structural water. This resulted in a final atmospheric water reservoir comparable to the present day total water budget of the Earth. The interaction of metallic iron with free water at the surface of the accreting Earth is considered. We carried out model calcualtions simulating these processes during accretion. It is assumed that these processes are the prime source of the terrestrial FeO component of silicates and oxides. It is demonstrated that the iron-water reaction would result in the absence of atmospheric/hydrospheric water, if homogeneous accretion is assumed. In order to obtain the necessary amount of terrestrial water, slightly heterogeneous accretion with initially 36 wt% iron planetesimals, as compared with a homogeneous value of 34 wt% is required.

  13. A SIFT ion-molecule study of some reactions in Titan's atmosphere. reactions of N(+), N(2)(+), and HCN(+) with CH(4), C(2)H(2), and C(2)H(4)

    NASA Technical Reports Server (NTRS)

    Anicich, Vincent G.; Wilson, Paul; McEwan, Murray J.

    2004-01-01

    The results of a study of the ion-molecule reactions of N(+), N(2)(+), and HCN(+) with methane, acetylene, and ethylene are reported. These studies were performed using the FA-SIFT at the University of Canterbury. The reactions studied here are important to understanding the ion chemistry in Titan's atmosphere. N(+) and N(2)(+) are the primary ions formed by photo-ionization and electron impact in Titan's ionosphere and drive Titan's ion chemistry. It is therefore very important to know how these ions react with the principal trace neutral species in Titan's atmosphere: Methane, acetylene, and ethylene. While these reactions have been studied before the product channels have been difficult to define as several potential isobaric products make a definitive answer difficult. Mass overlap causes difficulties in making unambiguous species assignments in these systems. Two discriminators have been used in this study to resolve the mass overlap problem. They are deuterium labeling and also the differences in reactivities of each isobar with various neutral reactants. Several differences have been found from the products in previous work. The HCN(+) ion is important in both Titan's atmosphere and in the laboratory.

  14. Evaluation of photon production data from neutron-induced reactions

    SciTech Connect

    Fu, C.Y.

    1980-01-01

    The evaluation methods and procedures used for generating the photon production data in the current Evaluated Nuclear Data File (ENDF/B, Version V) are reviewed. There are 42 materials in the General Purpose File of ENDF/B-V that contain data for prompt photon production. Almost all evaluations had substantial experimental data bases, but fewer than half of them employed any of the following evaluation methods. Only a few used theoretical techniques that are sophisticated enough to ensure internal consistency with other particle production data. Comments are made on four evaluation methods: the empirical formalism of Howerton et al., the Troubetzkoy model, the multiparticle Hauser-Feshbach/precompound model, and the Yost method. Critiques are also made on three procedures used for conserving photon energies in neutron capture reactions. The presence of photon production data in the file is useful for studying energy balance, since photon production generally accounts for a large portion of the reaction energy output. Problems found in energy balance checks are discussed. 9 figures, 1 table.

  15. Methyl Chavicol: Characterization of its Biogenic Emission Rate, Abundance, and Oxidation Products in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Bouvier-Brown, N. C.; Goldstein, A. H.; Worton, D. R.; Matross, D. M.; Gilman, J.; Kuster, W.; Degouw, J.; Cahill, T. M.; Holzinger, R.

    2008-12-01

    We report quantitative measurements of ambient atmospheric mixing ratios for methyl chavicol and determine its biogenic emission rate. Methyl chavicol, a biogenic oxygenated aromatic compound, is abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol was detected simultaneously by three in-situ instruments: gas chromatograph with mass spectrometer detector (GC-MS), proton transfer reaction mass spectrometer (PTR-MS), and thermal desorption aerosol GC-MS (TAG). Previously identified as a potential bark beetle disruptant, methyl chavicol atmospheric mixing ratios are strongly correlated with 2-methyl-3-buten-2-ol (MBO), a light and temperature dependent biogenic emission from the ponderosa pine trees at Blodgett Forest. Scaling from this correlation, methyl chavicol emissions account for 4-68 % of the carbon mass emitted as MBO in the daytime, depending on the season. From this relationship, we estimate a daytime basal emission rate of 0.72-10.2 μ gCg-1h-1, depending on needle age and seasonality. We also present the first observations of its oxidation products (4-methoxybenzaldehyde and 4-methyoxy benzene acetaldehyde) in the ambient atmosphere. Methyl chavicol is a major essential oil component of many species. We propose this newly- characterized biogenic compound should be included explicitly in both biogenic volatile organic carbon emission and atmospheric chemistry models.

  16. A survey of bimolecular ion-molecule reactions for use in modeling the chemistry of planetary atmospheres, cometary comae, and interstellar clouds - 1993 supplement

    NASA Technical Reports Server (NTRS)

    Anicich, V. G.

    1993-01-01

    This is a supplement to a previous paper (Anicich & Huntress 1986). It is a survey of bimolecular positive ion-molecule reactions with potential importance to the chemistry of planetary atmospheres, cometary comae, and interstellar clouds. This supplement covers the literature from 1986 through 1991, with some additional citations missed in the original survey. Over 200 new citations are included. A table of reactions is listed by reactant ion, and cross-references are provided for both ionic and neutral reactants and also for both ionic and neutral products.

  17. Rate constants for reactions between atmospheric reservoir species. 2. H sub 2 O

    SciTech Connect

    Hatakeyama, Shiro; Leu, Mingtaun )

    1989-07-27

    The kinetics of the reactions of H{sub 2}O with ClONO{sub 2}, N{sub 2}O{sub 5}, O{sub 3}, and COCl{sub 2} have been investigated by using a large-volume static cell and a Fourier transform infrared spectrometer at 296 K. Upper limits for the homogeneous gas-phase reaction rate constants of the ClONO{sub 2} + H{sub 2}O, N{sub 2}O{sub 5} + H{sub 2}O, O{sub 3} + H{sub 2}O, and COCl{sub 2} + H{sub 2}O reactions were found to be 3.4 {times} 10{sup {minus}21}, 2.8 {times} 10{sup {minus}21}, 1.1 {times} 10{sup {minus}22}, and 1.2 {times} 10{sup {minus}23}, respectively (all in units of cm{sup 3} s{sup {minus}1}), based on the observed decay rates of ClONO{sub 2}, N{sub 2}O{sub 5}, O{sub 3}, and COCl{sub 2}. Product analyses gave 0.82 {plus minus} 0.07 for the yield of HNO{sub 3} in the ClONO{sub 2} + H{sub 2}O {yields} HOCl + HNO{sub 3} reaction and 1.1 {plus minus} 0.3 for the yield of HNO{sub 3} from the N{sub 2}O{sub 5} + H{sub 2}O {yields} 2HNO{sub 3} reaction. The quoted error represents one standard deviation of the measurement. An attempt was also made to monitor possible reaction products such as H{sub 2}O{sub 2} for the O{sub 3} + H{sub 2}O reaction, and CO{sub 2} or HCl for the COCl{sub 2} + H{sub 2}O reaction. These results may be important in the elucidation of the springtime Antarctic ozone depletion over the past decade. The implication for NO{sub x} chemistry in the nighttime troposphere based on their results of the N{sub 2}O{sub 5} + H{sub 2}O reaction will be discussed.

  18. In situ measurements of heterogeneous reactions on ambient aerosol particles: Impacts on atmospheric chemistry and climate

    SciTech Connect

    Bertram, Timothy

    2015-02-11

    Aerosol particles play a critical role in the Earth’s energy budget through the absorption and scattering of radiation, and/or through their ability to form clouds and alter cloud lifetime. Heterogeneous and multi-phase reactions alter the climate-relevant properties of aerosol particles and catalyze reaction pathways that are energetically unfavorable in the gas phase. The chemical composition of aerosol particles dictates the kinetics of heterogeneous and multi-phase reactions. At present, the vast majority of the molecular level information on these processes has been determined in laboratory investigations on model aerosol systems. The work described here provides a comprehensive investigation into the reactivity of complex, ambient aerosol particles is proposed to determine: 1) how representative laboratory investigations of heterogeneous and multi-phase processes conducted on model, simple systems are of the real atmosphere, and 2) the impact of heterogeneous and multi-phase processes on ambient particle optical properties and their ability to nucleate clouds. This work has focused on the uptake kinetics for ammonia (NH3) and dinitrogen pentoxide (N2O5). The results of these investigations will be used to directly improve the representation of heterogeneous and multi-phase processes in global climate models, by identifying the key mechanistic drivers that control the variability in the observed kinetics.

  19. Common inorganic ions are efficient catalysts for organic reactions in atmospheric aerosols and other natural environments

    NASA Astrophysics Data System (ADS)

    Nozière, B.; Dziedzic, P.; Córdova, A.

    2009-01-01

    In this work, inorganic ammonium ions, NH4+, and carbonate ions, CO32-, are reported for the first time as catalysts for organic reactions in atmospheric aerosols and other natural environments at the Earth's surface. These reactions include the formation of C-C and C-O bonds by aldol condensation and acetal formation, and reveal a new aspect of the interactions between organic and inorganic materials in natural environments. The catalytic properties of inorganic ammonium ions, in particular, were not previously known in chemistry. The reactions were found to be as fast in tropospheric ammonium sulfate composition as in concentrated sulfuric acid. The ubiquitous presence and large concentrations of ammonium ions in tropospheric aerosols would make of ammonium catalysis a main consumption pathway for organic compounds in these aerosols, while acid catalysis would have a minor contribution. In particular, ammonium catalysis would account quantitatively for the aging of carbonyl compounds into secondary ''fulvic'' compounds in tropospheric aerosols, a transformation affecting the optical properties of these aerosols. In general, ammonium catalysis is likely to be responsible for many observations previously attributed to acid catalysis in the troposphere.

  20. Reaction Mechanism and Product Branching Ratios of the CH + C3H6 Reaction: A Theoretical Study.

    PubMed

    Ribeiro, Joao Marcelo; Mebel, Alexander M

    2016-03-24

    from experiment can be rationalized in terms of dynamical factors, which should favor direct dissociation of the CH3CHCH(•)CH2 precursor by H loss, especially to 1,2-butadiene, over its isomerization to (•)CH2CH2CHCH2 followed by the production of ethene + C2H3 radical, while 1-butyne might be formed through secondary H assisted isomerization of 1,2-butadiene. Overall, the calculations corroborate that the CH + C3H6 reaction could be a major source of 1,3-butadiene at low temperature and low pressure conditions in the interstellar medium and planetary atmospheres. PMID:26866464

  1. The Sentinel-4 Mission: Instrument Description and Atmospheric Composition Products

    NASA Astrophysics Data System (ADS)

    Veihelmann, B.; Ingmann, P.; Bazalgette Courreges-Lacoste, G.; Ahlers, B.; Stark, H.; Meijer, Y.

    2012-04-01

    Sentinel-4 (S4) is an operational satellite mission providing atmospheric composition data on a European basis with a fast (hourly) revisit time. The S4 mission is defined as an Ultra-violet Visible Near-infrared (UVN) spectrometer on the geostationary Meteosat Third Generation-Sounder (MTG-S) platforms together with utilisation of subsets of data from the MTG-Infra-Red Sounder onboard the same platforms and from the MTG-Flexible Combined Imager onboard the MTG-Imager (MTG-I) platforms. Key features of the S4/UVN instrument are the spectral range from 305 nm to 500 nm with a spectral resolution of 0.5 nm for the UV visible, and 750 nm to 770 nm with a spectral resolution of 0.12 nm in the Near-Infared, in combination with a low polarization sensitivity and a high radiometric accuracy (3% absolute, 0.05% relative spectral). The instrument shall observe Europe with a spatial sampling distance of 8 km at 45°N with a revisit time of 1 hour. The expected launch date of the first MTG-S platform is 2019, and the expected lifetime is 15 years (two S4/UVN instruments in sequence on two MTG-S platforms). The Sentinel-4 mission, together with Sentinel-5 and the Sentinel-5 Precursor missions, is part of the Global Monitoring for Environment and Security (GMES) space component. The primary objective of the Sentinel-4 mission is the observation of the diurnal cycle of tropospheric species in support of the air quality applications of GMES Atmosphere Services. The main target species of the Sentinel-4/UVN instrument are NO2, O3, HCHO, SO2, and aerosols. The presentation focuses on the Sentinel-4/UVN instrument and the atmospheric composition products.

  2. Temperature- and pH-dependent aqueous-phase kinetics of the reactions of glyoxal and methylglyoxal with atmospheric amines and ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Sedehi, Nahzaneen; Takano, Hiromi; Blasic, Vanessa A.; Sullivan, Kristin A.; De Haan, David O.

    2013-10-01

    Reactions of glyoxal (Glx) and methylglyoxal (MG) with primary amines and ammonium salts may produce brown carbon and N-containing oligomers in aqueous aerosol. 1H NMR monitoring of reactant losses and product appearance in bulk aqueous reactions were used to derive rate constants and quantify competing reaction pathways as a function of pH and temperature. Glx + ammonium sulfate (AS) and amine reactions generate products containing C-N bonds, with rates depending directly on pH: rate = (70 ± 60) M-1 s-1fAld [Glx]totfAm [Am]tot, where fAld is the fraction of aldehyde with a dehydrated aldehyde functional group, and fAm is the fraction of amine or ammonia that is deprotonated at a given pH. MG + amine reactions generate mostly aldol condensation products and exhibit less pH dependence: rate = 10[(0.36 ± 0.06) × pH - (3.6 ± 0.3)] M-1 s-1fAld [MG]tot [Am]tot. Aldehyde + AS reactions are less temperature-dependent (Ea = 18 ± 8 kJ mol-1) than corresponding amine reactions (Ea = 50 ± 11 kJ mol-1). Using aerosol concentrations of [OH] = 10-12 M, [amine]tot = [AS] = 0.1 M, fGlx = 0.046 and fMG = 0.09, we estimate that OH radical reactions are normally the major aerosol-phase sink for both dicarbonyl compounds. However, reactions with AS and amines together can account for up to 12 and 45% of daytime aerosol-phase glyoxal and methylglyoxal reactivity, respectively, in marine aerosol at pH 5.5. Reactions with AS and amines become less important in acidic or non-marine aerosol, but may still be significant atmospheric sources of brown carbon, imidazoles, and nitrogen-containing oligomers.

  3. A study of switchgrass pyrolysis: Product variability and reaction kinetics

    NASA Astrophysics Data System (ADS)

    Bovee, Jonathan Matthew

    Samples of the same cultivar of cave-in-rock switchgrass were harvested from plots in Frankenmuth, Roger City, Cass County, and Grand Valley, Michigan. It was determined that variation exists, between locations, among the pyrolytic compounds which can lead to variability in bio-oil and increased processing costs at bio-refineries to make hydrocarbon fuels. Washed and extractives-free switchgrass samples, which contain a lower alkali and alkaline earth metals content than untreated samples, were shown to produce lower amounts of acids, esters, furans, ketones, phenolics, and saccharides and also larger amounts of aldehydes upon pyrolysis. Although the minerals catalyzed pyrolytic reactions, there was no evidence indicating their effect on reducing the production of anhydrosugars, specifically levoglucosan. To further link minerals present in the biomass to a catalytic pathway, mathematic models were employed to determine the kinetic parameters of the switchgrass. While the calculated activation energies of switchgrass, using the FWO and KAS methods, were 227.7 and 217.8 kJ/mol, correspondingly, it was concluded that the activation energies for the switchgrass hemicellulose and cellulose peaks were 115.5 and 158.2 kJ/mol, respectively, using a modified model-fitting method. The minerals that effect the production of small molecules and levoglucosan also have an observable catalytic effect on switchgrass reaction rate, which may be quantifiable through the use of reaction kinetics so as to determine activation energy.

  4. VIIRS Atmospheric Products in the Community Satellite Processing Package (CSPP)

    NASA Astrophysics Data System (ADS)

    Cureton, G. P.; Gumley, L.; Mindock, S.; Martin, G.; Garcia, R. K.; Strabala, K.

    2012-12-01

    The Cooperative Institute for Meteorological Satellite Studies (CIMSS) has a long history of supporting the Direct Broadcast (DB) community for various sensors, recently with the International MODIS/AIRS Processing Package (IMAPP) for the NASA EOS polar orbiters Terra and Aqua. CIMSS has continued this effort into the NPP/JPSS (previously NPOESS) era with the development of the Community Satellite Processing Package (CSPP), supporting the VIIRS, CrIS and ATMS sensors on the Suomi National Polar-orbiting Partnership (Suomi NPP) spacecraft. In time it is intended that CSPP will support GOES-R, JPSS and other geostationary and polar orbiting platforms. Here we focus on the implementation and usage of the Visible Infrared Imaging Radiometer Suite (VIIRS) atmospheric product sub-packages within CSPP, which are based on the Interface Data Processing Segment (IDPS) code as implemented by Raytheon in the Algorithm Development Library (ADL). The VIIRS atmospheric algorithms available in CSPP include the Cloud Mask, Active Fires, Cloud Optical Properties, Cloud Top Parameters, and the Aerosol Optical Thickness algorithms. Each ADL sub-package consists of a binary executable and a series of configuration XML files. A series of python scripts handle ancillary data retrieval and preparation for ingest into ADL, manage algorithm execution, and provide a variety of execution options which are of utility in operational and algorithm development settings. Examples of these options, applied to operational and direct-broadcast VIIRS SDR data, are described.

  5. The Atmospheric Infrared Sounder Version 6 Cloud Products

    NASA Technical Reports Server (NTRS)

    Kahn, B. H.; Irion, F. W.; Dang, V. T.; Manning, E. M.; Nasiri, S. L.; Naud, C. M.; Blaisdell, J. M.; Schreier, M. M..; Yue, Q.; Bowman, K. W.; Fetzer, E. J.; Hulley, G. C.; Liou, K. N.; Lubin, D.; Ou, S. C.; Susskind, J.; Takano, Y.; Tian, B.; Worden, J. R.

    2014-01-01

    The version 6 cloud products of the Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instrument suite are described. The cloud top temperature, pressure, and height and effective cloud fraction are now reported at the AIRS field-of-view (FOV) resolution. Significant improvements in cloud height assignment over version 5 are shown with FOV-scale comparisons to cloud vertical structure observed by the CloudSat 94 GHz radar and the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP). Cloud thermodynamic phase (ice, liquid, and unknown phase), ice cloud effective diameter D(sub e), and ice cloud optical thickness (t) are derived using an optimal estimation methodology for AIRS FOVs, and global distributions for 2007 are presented. The largest values of tau are found in the storm tracks and near convection in the tropics, while D(sub e) is largest on the equatorial side of the midlatitude storm tracks in both hemispheres, and lowest in tropical thin cirrus and the winter polar atmosphere. Over the Maritime Continent the diurnal variability of tau is significantly larger than for the total cloud fraction, ice cloud frequency, and D(sub e), and is anchored to the island archipelago morphology. Important differences are described between northern and southern hemispheric midlatitude cyclones using storm center composites. The infrared-based cloud retrievals of AIRS provide unique, decadal-scale and global observations of clouds over portions of the diurnal and annual cycles, and capture variability within the mesoscale and synoptic scales at all latitudes.

  6. Glow-Discharge Production of Oxygen from the Martian Atmosphere

    NASA Astrophysics Data System (ADS)

    Hughes, Caleb; Outlaw, Ronald

    One of the most crucial aspects of any mission to Mars is a continual supply of oxygen for astronaut respiration on site. The most popular approach to this problem favors in-situ oxygen production on Mars, utilizing the CO2 Martian atmosphere. However, this requires a large energy budget. NASA's current plans for Mars include sending a system called MOXIE, which produces oxygen through solid oxide electrolysis at high temperatures. An alternative approach utilizes the 6 Torr Martian atmosphere to provide a continual source of oxygen by breaking down the molecule into CO and O using a glow-discharge. After dissociation, a thin film Agmembrane uniquely permeates the atomic oxygen which then recombines to O2 on the downstream side, where it is subsequently stored. By taking advantage of recent advances in thin film technology to reduce the thickness of the film to many orders of magnitude less than used in the initial study, a corresponding increase in O2 flux can be realized. The Ag thin film requires the support of a porous ceramic substructure. With this system, it is shown that this method produces a viable energy efficient alternative to MOXIE.

  7. TOPICAL REVIEW: Nucleation and aerosol processing in atmospheric pressure electrical discharges: powders production, coatings and filtration

    NASA Astrophysics Data System (ADS)

    Borra, Jean-Pascal

    2006-01-01

    This review addresses the production of nano-particles and the processing of particles injected in atmospheric pressure electrical discharges (APED). The mechanisms of formation and the evolution of particles suspended in gases are first presented, with numerical and experimental facilities. Different APED and related properties are then introduced for dc corona, streamer and spark filamentary discharges (FD), as well as for ac filamentary and homogeneous dielectric barrier discharges (DBD). Two mechanisms of particle production are depicted in APED: when FD interact with the surface of electrodes or dielectrics and when filamentary and homogeneous DBD induce reactions with gaseous precursors in volume. In both cases, condensable gaseous species are produced, leading to nano-sized particles by physical and chemical routes of nucleation. The evolution of the so-formed nano-particles, i.e. the growth by coagulation/condensation, the charging and the collection are detailed for each APED, with respect to fine powders production and thin films deposition. Finally, when particles are injected in APED, they undergo interfacial processes. Non-thermal plasmas charge particles for electro-collection and trigger heterogeneous chemical reactions for organic and inorganic films deposition. Heat exchanges in thermal plasmas enable powder purification, shaping, melting for hard coatings and fine powders production by reactive evaporation.

  8. Atmospheric Chemistry of Six Methyl-perfluoroheptene-ethers Used as Heat Transfer Fluid Replacement Compounds: Measured OH Radical Reaction Rate Coefficients, Atmospheric Lifetimes, and Global Warming Potentials

    NASA Astrophysics Data System (ADS)

    Jubb, A. M.; Gierczak, T.; Baasandorj, M.; Waterland, R. L.; Burkholder, J. B.

    2013-12-01

    Mixtures of methyl-perfluoroheptene-ethers (C7F13OCH3, MPHEs) are currently in use as a replacement for perfluorinated alkane (PFC) and polyether mixtures (both persistent greenhouse gases with atmospheric lifetimes >1000 years) used as heat transfer fluids. Currently, the atmospheric fate of the MPHE isomers are not well characterized, however, reaction with the OH radical is expected to be a dominant tropospheric loss process for these compounds. In order to assess the atmospheric lifetimes and environmental implications of MPHE use, rate coefficients for MPHE isomers' reaction with OH radicals are desired. In the work presented here, rate coefficients, k, for the gas-phase reaction of the OH radical with six MPHEs commonly used in commercial mixtures (isomers and stereoisomers) and their deuterated analogs (d3-MPHE) were determined at 296 K using a relative rate method with combined gas-chromatography/IR spectroscopy detection. A range of OH rate coefficient values was observed, up to a factor of 20× different, between the MPHE isomers with the (E)-stereoisomers exhibiting the greatest reactivity. The measured OH reaction rate coefficients for the d3-MPHE isomers were lower than the observed MPHE values although a large range of k values between isomers was still observed. The reduction in reactivity with deuteration signifies that the MPHE + OH reaction proceeds via both addition to the olefinic C=C bond and H-abstraction from the methyl ester group. OH addition to the C=C bond was determined to be the primary reaction channel. Atmospheric lifetimes with respect to the OH reaction for the six MPHE isomers were found to be in the range of days to months. The short lifetimes indicate that MPHE use will primarily impact tropospheric local and regional air quality. A MPHE atmospheric degradation mechanism will be presented. As part of this work, radiative efficiencies and global warming potentials (GWPs) for the MPHE isomers were estimated based on measured

  9. Manifestation of macroscopic correlations in elementary reaction kinetics. I. Irreversible reaction A+A-->product.

    PubMed

    Doktorov, Alexander B; Kipriyanov, Alexander A; Kipriyanov, Alexey A

    2010-05-28

    Using an modern many-particle method for the derivation of non-Markovian binary kinetic equations, we have treated theoretically the applicability of the encounter theory (ET) (the prototype of the collision theory) concepts to the widely known diffusion assisted irreversible bulk reaction A+A-->product (for example, radical reaction) in dilute solutions. The method shows that the agreement with the ET is observed when the familiar integral ET is employed which in this method is just a step in the derivation of kinetic equations. It allows for two-particle correlations only, but fails to take account of correlation of reactant simultaneously with the partner of the encounter and the reactant in the bulk. However, the next step leading to the modified ET under transformation of equations to the regular form both extends the time range of the applicability of ET rate equation (as it was for reactions proceeding with one of the reactants in excess), and gives the equation of the generalized ET. In full agreement with physical considerations, this theory reveals macroscopic correlations induced by the encounters in the reservoir of free walks. This means that the encounters of reactants in solution are correlated on a rather large time interval of the reaction. Though any nonstationary (non-Markovian) effects manifest themselves rather weakly in the kinetics of the bimolecular reaction in question, just the existence of the revealed macroscopic correlations in the binary theory is of primary importance. In particular, it means that the well-known phenomena which are generally considered to be associated solely with correlation of particles on the encounter (for example, chemically induced dynamic nuclear polarization) may be induced by correlation in the reservoir of free random walks of radicals in solution. PMID:20515095

  10. Atmospheric pressure photoionization mass spectrometry as a tool for the investigation of the hydrolysis reaction mechanisms of phosphite antioxidants

    NASA Astrophysics Data System (ADS)

    Papanastasiou, M.; McMahon, A. W.; Allen, N. S.; Johnson, B. W.; Keck-Antoine, K.; Santos, L.; Neumann, M. G.

    2008-08-01

    The hydrolysis reaction mechanism of phosphite antioxidants is investigated by liquid chromatography-mass spectrometry (LC/MS). The phosphites were chosen because they differed in chemical structure and phosphorus content. Dopant assisted-atmospheric pressure photoionization (DA-APPI) is chosen as the ion source for the ionization of the compounds. In our previous work, DA-APPI was shown to offer an attractive alternative to atmospheric pressure chemical ionization (APCI) since it provided background-ion free mass spectra and higher sensitivity [M. Papanastasiou, et al., Polymer Degradation and Stability 91 (11) (2006) 2675-2682]. In positive ion mode, the molecules are generally detected in their protonated form. In negative ion mode, the phosphites are unstable and only fragment ions are observed; these however, are characteristic of each phosphite and may be used for the identification of the analytes in complex mixtures. The analytes under investigation are exposed to accelerated humid ageing conditions and their hydrolytic pathway and stability is investigated. Different substituents around the phosphorus atom are shown to have a significant effect on the stability of the phosphites, with phenol substituents producing very hydrolytically stable structures. Alkanox P24 and PEP-36 follow a similar hydrolytic pathway via the scission of the first and then the second POphenol bonds, eventually leading to the formation of phenol, phosphorous acid and pentaerythritol as end products. HP-10 exhibits a rather different structure and the products detected suggest scission of either the POhydrocarbon or one of the POphenol bonds. A phenomenon similar to that of autocatalysis is observed for all phosphites and is attributed to the formation of dialkyl phosphites as intermediate products.

  11. Acid–base chemical reaction model for nucleation rates in the polluted atmospheric boundary layer

    PubMed Central

    Chen, Modi; Titcombe, Mari; Jiang, Jingkun; Jen, Coty; Kuang, Chongai; Fischer, Marc L.; Eisele, Fred L.; Siepmann, J. Ilja; Hanson, David R.; Zhao, Jun; McMurry, Peter H.

    2012-01-01

    Climate models show that particles formed by nucleation can affect cloud cover and, therefore, the earth's radiation budget. Measurements worldwide show that nucleation rates in the atmospheric boundary layer are positively correlated with concentrations of sulfuric acid vapor. However, current nucleation theories do not correctly predict either the observed nucleation rates or their functional dependence on sulfuric acid concentrations. This paper develops an alternative approach for modeling nucleation rates, based on a sequence of acid–base reactions. The model uses empirical estimates of sulfuric acid evaporation rates obtained from new measurements of neutral molecular clusters. The model predicts that nucleation rates equal the sulfuric acid vapor collision rate times a prefactor that is less than unity and that depends on the concentrations of basic gaseous compounds and preexisting particles. Predicted nucleation rates and their dependence on sulfuric acid vapor concentrations are in reasonable agreement with measurements from Mexico City and Atlanta. PMID:23091030

  12. Products of the OH radical-initiated reactions of 2- and 3-hexyl nitrate

    NASA Astrophysics Data System (ADS)

    Aschmann, Sara M.; Arey, Janet; Atkinson, Roger

    2012-01-01

    Products of the gas-phase reaction of OH radicals with 2-hexyl nitrate (containing 13% 3-hexyl nitrate) have been investigated by gas chromatography with mass spectral and flame ionization detection, and by direct air sampling atmospheric pressure ionization tandem mass spectrometry. The products identified and quantified from 2-hexyl nitrate were: 2-hexanone (8.6 ± 1.3%), propanal (3.4 ± 0.8%), butanal (2.3 ± 0.6%) and 5-hydroxy-2-hexanone (25%), where the molar yields are given in parentheses. 3-Hexanone was observed from the 3-hexyl nitrate reaction, with a molar formation yield of 9.5 ± 2.1%. Organic nitrates of molecular weight 133, 161, 177 and 208 were also observed, and these are attributed to C 4-carbonyl nitrate(s), C 6-carbonyl-nitrates, C 6-hydroxycarbonyl-nitrates and C 6-dinitrates, respectively, and are expected to account for all or most of the non-quantified reaction products from OH + 2- and 3-hexyl nitrate. 5-Hydroxy-2-hexanone formation indicates that the CH 3CH(ONO 2)CH 2CH 2CH(O rad )CH 3 alkoxy radical dominantly reacts by isomerization.

  13. Reaction pathways for bio-active species in a He/H2O atmospheric pressure capacitive discharge

    NASA Astrophysics Data System (ADS)

    Ding, Ke; Lieberman, M. A.

    2015-01-01

    Helium/trace gas atmospheric pressure radio-frequency (rf) capacitive discharges have increasing biomedical applications. We have performed a principal pathway analysis for a chemically complex, bounded He/H2O atmospheric pressure, planar capacitive discharge, with a discharge gap of 0.5 mm and a power of 0.85 W cm-2 at 13.56 MHz (ne ≈ 1.6 × 1017 m-3). The discharge is embedded in a larger volume in which the H2O fraction is controlled to be 0.001. The generation and loss pathways for eleven species of interest for discharge maintenance and biomedical applications have been determined. The production and consumption pathways of He*, H2O, {{\\text{H}}11}\\text{O}5+ and electrons are found to be tightly coupled. The metastable He* generated by electron impact excitation of He is mostly consumed by Penning reactions with H2O, followed by subsequent three-body association reactions with H2O, to form the dominant positive ion, {{\\text{H}}11}\\text{O}5+ . The main loss pathways for {{\\text{H}}11}\\text{O}5+ are ion cluster fragmentations at the wall, which are important generation pathways for H2O. The generation and loss pathways for electrons are almost the same as for {{\\text{H}}11}\\text{O}5+ . OH and H2O2 generation and loss are strongly coupled, and they are important intermediate species in the generation pathways for the purely O-containing bio-active species: O2(a), O, O3 and O*. The generation and loss pathways for the latter four species were found to be strongly coupled by volume and surface processes, with O2 as an important precursor. The generation of O2 from H2O involves H2O2 as a key long-lived intermediate.

  14. Theoretical aspects of product formation from the NCO + NO reaction

    SciTech Connect

    Lin, M.C.; He, Y. ); Melius, C.F. )

    1993-09-09

    The reaction of NCO with NO, an important elementary process involved in the reduction of NO[sub x] by HNCO, has been studied theoretically using the BAC-MP4 technique in conjunction with RRKM calculations. The computed molecular structures and thermochemical data for various intermediates and transition states suggest that the reaction takes place primarily via the singlet, ground electronic state OCNNO molecule according to the following mechanism; (step a) NCO + NO [leftrightarrow] [sup 1]OCNNO [yields] N[sub 2]O + CO; (step b) NCO + NO [leftrightarrow] [sup 1]OCNNO [yields] c-OCNNO[minus] N[sub 2] + CO[sub 2]. The formation of N[sub 2]O + CO occurs by the fragmentation of the singlet OCNNO intermediate step (a), whereas the production of N[sub 2] + CO[sub 2] by cyclization-fragmentation occurs via step b. The tight transition states leading to the formation of these products, coupled with the loose entrance channel, give rise to the experimentally observed strong negative temperature dependence which can be quantitatively accounted for by the results of RRKM calculations based on the BAC-MP4 data. The experimentally measured product branching ratio for channels a and b could be accounted for theoretically by lowering the calculated energy barrier for step a by 3.6 kcal/mol, corresponding to about 15% of the barrier height. 22 refs., 3 figs., 5 tabs.

  15. Reaction of atomic bromine with acetylene and loss rate of atmospheric acetylene due to reaction with OH, Cl, O, and Br

    NASA Technical Reports Server (NTRS)

    Payne, W. A.; Nava, D. F.; Brunning, J.; Stief, L. J.

    1986-01-01

    The first-order, diffusion, and bimolecular rate constants for the reaction Br + C2H2 yields C2H3Br are evaluated. The rate constants are measured at 210, 248, 298, and 393 K and at pressures between 15-100 torr Ar using flash photolysis combined with time-resolved detection of atomic bromine via Br resonance radiation. It is observed that the reaction is not affected by pressure or temperature and the bimolecular constant = (4.0 + or - 0.8) x 10 to the -15th cu cm/sec with an error of two standard deviations. The C2H2 + Br reaction rates are compared with reactions of C2H2 with Cl, OH, NH2, and H. The loss rates for atmospheric C2H2 for reactions with OH, Cl, O, and Br are calculated as a function of altitude.

  16. Chemical kinetic studies of atmospheric reactions using tunable diode laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Worsnop, Douglas R.; Nelson, David D.; Zahniser, Mark S.

    1993-01-01

    IR absorption using tunable diode laser spectroscopy provides a sensitive and quantitative detection method for laboratory kinetic studies of atmospheric trace gases. Improvements in multipass cell design, real time signal processing, and computer controlled data acquisition and analysis have extended the applicability of the technique. We have developed several optical systems using off-axis resonator mirror designs which maximize path length while minimizing both the sample volume and the interference fringes inherent in conventional 'White' cells. Computerized signal processing using rapid scan (300 kHz), sweep integration with 100 percent duty cycle allows substantial noise reduction while retaining the advantages of using direct absorption for absolute absorbance measurements and simultaneous detection of multiple species. Peak heights and areas are determined by curve fitting using nonlinear least square methods. We have applied these techniques to measurements of: (1) heterogeneous uptake chemistry of atmospheric trace gases (HCl, H2O2, and N2O5) on aqueous and sulfuric acid droplets; (2) vapor pressure measurements of nitric acid and water over prototypical stratospheric aerosol (nitric acid trihydrate) surfaces; and (3) discharge flow tube kinetic studies of the HO2 radical using isotopic labeling for product channel and mechanistic analysis. Results from each of these areas demonstrate the versatility of TDL absorption spectroscopy for atmospheric chemistry applications.

  17. Passive sequestration of atmospheric CO2 through coupled plant-mineral reactions in urban soils.

    PubMed

    Manning, David A C; Renforth, Phil

    2013-01-01

    Photosynthetic removal of CO(2) from the atmosphere is an important planetary carbon dioxide removal mechanism. Naturally, an amount equivalent to all atmospheric carbon passes through the coupled plant-soil system within 7 years. Plants cycle up to 40% of photosynthesized carbon through their roots, providing a flux of C at depth into the soil system. Root-exuded carboxylic acids have the potential to supply 4-5 micromoles C hr(-1)g(-1) fresh weight to the soil solution, and enhance silicate mineral weathering. Ultimately, the final product of these root-driven processes is CO(2), present in solution as bicarbonate. This combines with Ca liberated by corrosion associated with silicate mineral weathering to enter the soil-water system and to produce pedogenic calcium carbonate precipitates. Combining understanding of photosynthesis and plant root physiology with knowledge of mineral weathering provides an opportunity to design artificial soils or to plan land use in ways that maximize removal and sequestration of atmospheric CO(2) through artificially enhanced pedogenic carbonate precipitation. This process requires relatively low energy and infrastructure inputs. It offers a sustainable carbon dioxide removal mechanism analogous to the use of constructed wetlands for the passive remediation of contaminated waters, and is likely to achieve wide public acceptance. PMID:22616942

  18. Computational study of the reaction mechanism and kinetics of ethyl acrylate ozonolysis in atmosphere

    NASA Astrophysics Data System (ADS)

    Sun, Yanhui; Cao, Haijie; Han, Dandan; Li, Jing; He, Maoxia; Wang, Chen

    2012-06-01

    The reaction mechanism for the ozonolysis of ethyl acrylate (EA) has been investigated at the CCSD(T)/6-31G(d)+CF//B3LYP/6-31+G(d,p) level of theory. The profile of the potential energy surface (PES) is constructed. Ozone adds to EA via a cyclic transition state to produce a highly unstable primary ozonide which can decompose readily. Over the temperature range of 200-2000 K, the total and individual rate constants are obtained by employing multichannel Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The calculated rate constants are 1.37 × 10-18 cm3 molecule-1 s-1 at 294 K and 1.65 × 10-18 cm3 molecule-1 s-1 at 298 K under the pressure of 760 Torr. The main products of the reactions are ethyl glyoxylate and formaldehyde. These results are in good agreement with the previous experimental data. Several experimental uncertain products are identified. The branching ratios of main reaction paths are also discussed at different temperatures and pressures.

  19. The NO+O{sub 3} reaction: A triple oxygen isotope perspective on the reaction dynamics and atmospheric implications for the transfer of the ozone isotope anomaly

    SciTech Connect

    Savarino, J.; Morin, S.; Baroni, M.; Bhattacharya, S. K.; Doussin, J.-F.

    2008-05-21

    Atmospheric nitrate shows a large oxygen isotope anomaly ({delta} {sup 17}O), characterized by an excess enrichment of {sup 17}O over {sup 18}O, similar to the ozone molecule. Modeling and observations assign this specific isotopic composition mainly to the photochemical steady state that exists in the atmosphere between ozone and nitrate precursors, namely, the nitrogen oxides (NO{sub x}=NO+NO{sub 2}). However, this transfer is poorly quantified and is built on unverified assumptions about which oxygen atoms of ozone are transferred to NO{sub x}, greatly weakening any interpretation of the nitrate oxygen isotopic composition in terms of chemical reaction pathways and the oxidation state of the atmosphere. With the aim to improve our understanding and quantify how nitrate inherits this unusual isotopic composition, we have carried out a triple isotope study of the reaction NO+O{sub 3}. Using ozone intramolecular isotope distributions available in the literature, we have found that the central atom of the ozone is abstracted by NO with a probability of (8{+-}5)%({+-}2{sigma}) at room temperature. This result is at least qualitatively supported by dynamical reaction experiments, the non-Arrhenius behavior of the kinetic rate of this reaction, and the kinetic isotope fractionation factor. Finally, we have established the transfer function of the isotope anomaly of O{sub 3} to NO{sub 2}, which is described by the linear relationship {delta} {sup 17}O(NO{sub 2})=Ax{delta} {sup 17}O(O{sub 3})+B, with A=1.18{+-}0.07({+-}1{sigma}) and B=(6.6{+-}1.5) per mille ({+-}1{sigma}). Such a relationship can be easily incorporated into models dealing with the propagation of the ozone isotope anomaly among oxygen-bearing species in the atmosphere and should help to better interpret the oxygen isotope anomaly of atmospheric nitrate in terms of its formation reaction pathways.

  20. The NO +O3 reaction: A triple oxygen isotope perspective on the reaction dynamics and atmospheric implications for the transfer of the ozone isotope anomaly

    NASA Astrophysics Data System (ADS)

    Savarino, J.; Bhattacharya, S. K.; Morin, S.; Baroni, M.; Doussin, J.-F.

    2008-05-01

    Atmospheric nitrate shows a large oxygen isotope anomaly (ΔO17), characterized by an excess enrichment of O17 over O18, similar to the ozone molecule. Modeling and observations assign this specific isotopic composition mainly to the photochemical steady state that exists in the atmosphere between ozone and nitrate precursors, namely, the nitrogen oxides (NOx=NO+NO2). However, this transfer is poorly quantified and is built on unverified assumptions about which oxygen atoms of ozone are transferred to NOx, greatly weakening any interpretation of the nitrate oxygen isotopic composition in terms of chemical reaction pathways and the oxidation state of the atmosphere. With the aim to improve our understanding and quantify how nitrate inherits this unusual isotopic composition, we have carried out a triple isotope study of the reaction NO +O3. Using ozone intramolecular isotope distributions available in the literature, we have found that the central atom of the ozone is abstracted by NO with a probability of (8±5)%(±2σ) at room temperature. This result is at least qualitatively supported by dynamical reaction experiments, the non-Arrhenius behavior of the kinetic rate of this reaction, and the kinetic isotope fractionation factor. Finally, we have established the transfer function of the isotope anomaly of O3 to NO2, which is described by the linear relationship ΔO17(NO2)=A ×ΔO17(O3)+B, with A =1.18±0.07(±1σ) and B =(6.6±1.5)‰(±1σ). Such a relationship can be easily incorporated into models dealing with the propagation of the ozone isotope anomaly among oxygen-bearing species in the atmosphere and should help to better interpret the oxygen isotope anomaly of atmospheric nitrate in terms of its formation reaction pathways.

  1. Surface reactions as carbon removal mechanism in deposition of silicon dioxide films at atmospheric pressure

    SciTech Connect

    Reuter, R.; Ellerweg, D.; Keudell, A. von; Benedikt, J.

    2011-03-14

    The deposition of thin SiO{sub x}C{sub y}H{sub z} or SiO{sub x}H{sub y} films by means of an atmospheric pressure microplasma jet with helium/hexamethyldisiloxane (HMDSO)/O{sub 2} mixtures and the surface reactions involving oxygen have been studied. It is shown, that the carbon content in the film can be controlled by choosing the right O{sub 2}/HMDSO ratio in the gas mixture. The microplasma jet geometry and localization of the deposition at a spot of few square millimeters allows studying the role of oxygen in the deposition process. This is done by alternating application of He/HMDSO plasma and He/O{sub 2} plasma to the same deposition area, here achieved by a treatment of a rotating substrate by two jets with above mentioned gas mixtures. It is shown that carbon-free SiO{sub x}H{sub y} film can be deposited in this way and that surface reaction with oxygen is the main loss mechanism of carbon from the film.

  2. Methyl chavicol: characterization of its biogenic emission rate, abundance, and oxidation products in the atmosphere

    NASA Astrophysics Data System (ADS)

    Bouvier-Brown, N. C.; Goldstein, A. H.; Worton, D. R.; Matross, D. M.; Gilman, J. B.; Kuster, W. C.; Welsh-Bon, D.; Warneke, C.; de Gouw, J. A.; Cahill, T. M.; Holzinger, R.

    2008-11-01

    We report measurements of ambient atmospheric mixing ratios for methyl chavicol and determine its biogenic emission rate. Methyl chavicol, a biogenic oxygenated aromatic compound, is abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol was detected simultaneously by three in-situ instruments a gas chromatograph with mass spectrometer detector (GC-MS), a proton transfer reaction mass spectrometer (PTR-MS), and a thermal desorption aerosol GC-MS (TAG) and found to be abundant within and above Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. Methyl chavicol atmospheric mixing ratios are strongly correlated with 2-methyl-3-buten-2-ol (MBO), a light- and temperature-dependent biogenic emission from the ponderosa pine trees at Blodgett Forest. Scaling from this correlation, methyl chavicol emissions account for 4 68% of the carbon mass emitted as MBO in the daytime, depending on the season. From this relationship, we estimate a daytime basal emission rate of 0.72 10.2 μgCg-1h-1, depending on needle age and seasonality. We also present the first observations of its oxidation products (4-methoxybenzaldehyde and 4-methyoxy benzene acetaldehyde) in the ambient atmosphere. Methyl chavicol is a major essential oil component of many plant species. This work suggests that methyl chavicol plays a significant role in the atmospheric chemistry of Blodgett Forest, and potentially other sites, and should be included explicitly in both biogenic volatile organic carbon emission and atmospheric chemistry models.

  3. Polynuclear aromatic hydrocarbon degradation by heterogeneous reactions with N 2O 5 on atmospheric particles

    NASA Astrophysics Data System (ADS)

    Kamens, Richard M.; Guo, Jiazhen; Guo, Zhishi; McDow, Stephen R.

    The degradation of particulate polynuclear aromatic hydrocarbons (PAH) on atmospheric soot particles in the presence of gas phase dinitrogen pentoxide (N 2O 5) was explored. Dilute diesel and wood soot particles containing PAH were reacted with˜10ppm of N 2O 5 in a 200 ℓ continuous stirred tank reactor (CSTR). To provide a stable source of particles for reaction in the CSTR, diesel or wood soot particles were injected at night into a 25 m 3 Teflon outdoor chamber. The large chamber served as a reservoir for the feed aerosol, and the aerosol could then be introduced at a constant flow rate into the CSTR. PAH-N 2O 5 heterogeneous rate constants for wood soot at 15°C ranged from2 × 10 -18to5 × 10 -18 cm 3 molecules -1 s -1. For diesel soot the rate constants at 16°C were higher and ranged from5 × 10 -18to30 × 10 -18 cm 3 molecules -1 s -1. Comparisons with other studies suggest that sunlight is the most important factor which influences PAH decay. This is followed by ozone, NO 2, N 2O 5 and nitric acid. The rate constants of nitro-PAH formation from a parent PAH and N 2O 5 were of the order of1 × 10 -19-1 × 10 -18 molecules -1s -1. The uncertainty associated with all of these rate constants is± a factor of 3. Given, however, the small magnitude of the rate constants and the low levels of N 2O 5 present in the atmosphere, we concluded that PAH heterogeneous reactions with gas phase N 2O 5 degrade particle-bound PAH or to form nitro-PAH from PAH are not very important. (Direct application of the specific rate constants derived in this study to ambient atmospheres should not be undertaken unless the ambient particle size distributions and chemical composition of the particles are similar to the ones reported in this study.)

  4. Photochemical parameters of atmospheric source gases: accurate determination of OH reaction rate constants over atmospheric temperatures, UV and IR absorption spectra

    NASA Astrophysics Data System (ADS)

    Orkin, V. L.; Khamaganov, V. G.; Martynova, L. E.; Kurylo, M. J.

    2012-12-01

    The emissions of halogenated (Cl, Br containing) organics of both natural and anthropogenic origin contribute to the balance of and changes in the stratospheric ozone concentration. The associated chemical cycles are initiated by the photochemical decomposition of the portion of source gases that reaches the stratosphere. Reactions with hydroxyl radicals and photolysis are the main processes dictating the compound lifetime in the troposphere and release of active halogen in the stratosphere for a majority of halogen source gases. Therefore, the accuracy of photochemical data is of primary importance for the purpose of comprehensive atmospheric modeling and for simplified kinetic estimations of global impacts on the atmosphere, such as in ozone depletion (i.e., the Ozone Depletion Potential, ODP) and climate change (i.e., the Global Warming Potential, GWP). The sources of critically evaluated photochemical data for atmospheric modeling, NASA/JPL Publications and IUPAC Publications, recommend uncertainties within 10%-60% for the majority of OH reaction rate constants with only a few cases where uncertainties lie at the low end of this range. These uncertainties can be somewhat conservative because evaluations are based on the data from various laboratories obtained during the last few decades. Nevertheless, even the authors of the original experimental works rarely estimate the total combined uncertainties of the published OH reaction rate constants to be less than ca. 10%. Thus, uncertainties in the photochemical properties of potential and current atmospheric trace gases obtained under controlled laboratory conditions still may constitute a major source of uncertainty in estimating the compound's environmental impact. One of the purposes of the presentation is to illustrate the potential for obtaining accurate laboratory measurements of the OH reaction rate constant over the temperature range of atmospheric interest. A detailed inventory of accountable sources of

  5. Production of Energetic Light Fragments in Spallation Reactions

    NASA Astrophysics Data System (ADS)

    Mashnik, Stepan G.; Kerby, Leslie M.; Gudima, Konstantin K.; Sierk, Arnold J.

    2014-03-01

    Different reaction mechanisms contribute to the production of light fragments (LF) from nuclear reactions. Available models cannot accurately predict emission of LF from arbitrary reactions. However, the emission of LF is important formany applications, such as cosmic-ray-induced single event upsets, radiation protection, and cancer therapy with proton and heavy-ion beams, to name just a few. The cascade-exciton model (CEM) and the Los Alamos version of the quark-gluon string model (LAQGSM), as implemented in the CEM03.03 and LAQGSM03.03 event generators used in the Los Alamos Monte Carlo transport code MCNP6, describe quite well the spectra of fragments with sizes up to 4He across a broad range of target masses and incident energies. However, they do not predict high-energy tails for LF heavier than 4He. The standard versions of CEM and LAQGSM do not account for preequilibrium emission of LF larger than 4He. The aim of our work is to extend the preequilibrium model to include such processes. We do this by including the emission of fragments heavier than 4He at the preequilibrium stage, and using an improved version of the Fermi Break-up model, providing improved agreement with various experimental data.

  6. Formation of high-molecular-weight compounds via the heterogeneous reactions of gaseous C8-C10 n-aldehydes in the presence of atmospheric aerosol components

    NASA Astrophysics Data System (ADS)

    Han, Yuemei; Kawamura, Kimitaka; Chen, Qingcai; Mochida, Michihiro

    2016-02-01

    A laboratory study on the heterogeneous reactions of straight-chain aldehydes was performed by exposing n-octanal, nonanal, and decanal vapors to ambient aerosol particles. The aerosol and blank filters were extracted using methanol. The extracts were nebulized and the resulting compositions were examined using a high-resolution time-of-flight aerosol mass spectrometer. The mass spectral analysis showed that the exposures of the aldehydes to aerosol samples increased the peak intensities in the high mass range. The peaks in the mass spectra of the aerosol samples after exposure to different aldehydes were characterized by a homologous series of peak shifts due to the addition of multiple CH2 units. This result is explained by the formation of high-molecular-weight (HMW) compounds that contain single or multiple aldehyde moieties. The HMW fragment peaks for the blank filters exposed to n-aldehydes were relatively weak, indicating an important contribution from the ambient aerosol components to the formation of the HMW compounds. Among the factors affecting the overall interaction of aldehydes with atmospheric aerosol components, gas phase diffusion possibly limited the reactions under the studied conditions; therefore, their occurrence to a similar degree in the atmosphere is not ruled out, at least for the reactions involving n-nonanal and decanal. The major formation pathways for the observed HMW products may be the self-reactions of n-aldehydes mediated by atmospheric aerosol components and the reactions of n-aldehydes with organic aerosol components. The observed formation of HMW compounds encourages further investigations into their effects on the aerosol properties as well as the organic aerosol mass in the atmosphere.

  7. Reactions of superoxide with myeloperoxidase and its products.

    PubMed

    Winterbourn, Christine C; Kettle, Anthony J

    2004-10-01

    Myeloperoxidase (MPO) uses hydrogen peroxide to oxidize chloride to hypochlorous acid. It also converts numerous substrates to reactive free radicals. When released by neutrophils, the enzyme operates in the presence of a flux of superoxide. We show that superoxide has a profound influence on oxidative reactions catalysed by MPO. It reacts directly with the enzyme to modulate production of hypochlorous acid. Within neutrophil phagosomes, where MPO functions to kill micro-organisms, it may be the preferred substrate for the enzyme. Superoxide also reacts rapidly with radicals generated by MPO, e.g. from tyrosine and tyrosyl peptides. Initial products are organic peroxides. These species are likely to be toxic and contribute to the pathophysiological actions of MPO. PMID:15507767

  8. The Influence of Atmospheric Conditions on the Production of Ozone during VOC Oxidation

    NASA Astrophysics Data System (ADS)

    Coates, J.; Butler, T. M.

    2015-12-01

    Tropospheric ozone is a short-lived climate forcing pollutant that is detrimental to human health and crop growth. Reactions involving volatile organic compounds (VOC) and nitrogen oxides (NOx) in the presence of sunlight produce ozone. Ozone production is a non-linear function of the concentrations of both NOx and VOC, with VOC acting as the "fuel" for ozone production and NOx as the "catalyst". Different VOC, due to their differing structure and carbon content, have different maximum potential to produce ozone. Due to different degrees of reactivity, VOC also differ in the time taken to reach this maximum ozone production potential under ideal conditions. Ozone production is also influenced by meteorological factors such as radiation, temperature, advection and mixing, which may alter the rate of ozone production, and the degree to which VOC are able to reach their maximum ozone production potential. Identifying the chemical and meteorological processes responsible for controlling the degree to which VOC are able to reach their maximum ozone production potential could inform decisions on emission control to efficiently tackle high levels of tropospheric ozone. In this study we use a boxmodel to determine the chemical processes affecting ozone production under different meteorological and chemical conditions. The chemistry scheme used by the boxmodel is "tagged" for each initial VOC enabling attribution of ozone production to its VOC source. We systematically vary a number of meteorological parameters along with the source of NOx within the box model to simulate a range of atmospheric conditions. These simulations are compared with a control simulation done under conditions of maximum ozone formation to determine which parameters affect the rate at which VOC produce ozone and the extent to which they reach their maximum potential to produce ozone. We perform multi-day simulations in order to examine whether these processes can influence ozone production over

  9. Removal of triclosan via peroxidases-mediated reactions in water: Reaction kinetics, products and detoxification.

    PubMed

    Li, Jianhua; Peng, Jianbiao; Zhang, Ya; Ji, Yuefei; Shi, Huanhuan; Mao, Liang; Gao, Shixiang

    2016-06-01

    This study investigated and compared reaction kinetics, product characterization, and toxicity variation of triclosan (TCS) removal mediated by soybean peroxidase (SBP), a recognized potential peroxidase for removing phenolic pollutants, and the commonly used horseradish peroxidase (HRP) with the goal of assessing the technical feasibility of SBP-catalyzed removal of TCS. Reaction conditions such as pH, H2O2 concentration and enzyme dosage were found to have a strong influence on the removal efficiency of TCS. SBP can retain its catalytic ability to remove TCS over broad ranges of pH and H2O2 concentration, while the optimal pH and H2O2 concentration were 7.0 and 8μM, respectively. 98% TCS was removed with only 0.1UmL(-1) SBP in 30min reaction time, while an HRP dose of 0.3UmL(-1) was required to achieve the similar conversion. The catalytic performance of SBP towards TCS was more efficient than that of HRP, which can be explained by catalytic rate constant (KCAT) and catalytic efficiency (KCAT/KM) for the two enzymes. MS analysis in combination with quantum chemistry computation showed that the polymerization products were generated via CC and CO coupling pathways. The polymers were proved to be nontoxic through growth inhibition of green alga (Scenedesmus obliquus). Taking into consideration of the enzymatic treatment cost, SBP may be a better alternative to HRP upon the removal and detoxification of TCS in water/wastewater treatment. PMID:26921508

  10. 40 CFR 721.10154 - Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides, reaction products with silica.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., dicoco alkyldimethyl, chlorides, reaction products with silica. (a) Chemical substance and significant... alkyldimethyl, chlorides, reaction products with silica. 721.10154 Section 721.10154 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF...

  11. 40 CFR 721.10154 - Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides, reaction products with silica.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., dicoco alkyldimethyl, chlorides, reaction products with silica. (a) Chemical substance and significant... alkyldimethyl, chlorides, reaction products with silica. 721.10154 Section 721.10154 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF...

  12. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo substituted phenyl azo... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10126 Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato...

  13. 40 CFR 721.10154 - Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides, reaction products with silica.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., dicoco alkyldimethyl, chlorides, reaction products with silica. (a) Chemical substance and significant... alkyldimethyl, chlorides, reaction products with silica. 721.10154 Section 721.10154 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF...

  14. 40 CFR 721.10154 - Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides, reaction products with silica.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., dicoco alkyldimethyl, chlorides, reaction products with silica. (a) Chemical substance and significant... alkyldimethyl, chlorides, reaction products with silica. 721.10154 Section 721.10154 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF...

  15. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo substituted phenyl azo... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10126 Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato...

  16. 40 CFR 721.10154 - Quaternary ammonium compounds, dicoco alkyldimethyl, chlorides, reaction products with silica.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., dicoco alkyldimethyl, chlorides, reaction products with silica. (a) Chemical substance and significant... alkyldimethyl, chlorides, reaction products with silica. 721.10154 Section 721.10154 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF...

  17. Experimental measurements of low temperature rate coefficients for neutral-neutral reactions of interest for atmospheric chemistry of Titan, Pluto and Triton: reactions of the CN radical.

    PubMed

    Morales, Sébastien B; Le Picard, Sébastien D; Canosa, André; Sims, Ian R

    2010-01-01

    The kinetics of the reactions of cyano radical, CN (X2sigma+) with three hydrocarbons, propane (CH3CH2CH3), propene (CH3CH=CH2) and 1-butyne (CH[triple band]CCH2CH3) have been studied over the temperature range of 23-298 K using a CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme or Reaction Kinetics in Uniform Supersonic Flow) apparatus combined with the pulsed laser photolysis-laser induced fluorescence technique. These reactions are of interest for the cold atmospheres of Titan, Pluto and Triton, as they might participate in the formation of nitrogen and carbon bearing molecules, including nitriles, that are thought to play an important role in the formation of hazes and biological molecules. All three reactions are rapid with rate coefficients in excess of 10(-10) cm3 molecule(-1) s(-1) at the lowest temperatures of this study and show behaviour characteristic of barrierless reactions. Temperature dependences, different for each reaction, are compared to those used in the most recent photochemical models of Titan's atmosphere. PMID:21302546

  18. Water-soluble reaction products from ozonolysis of grasses

    SciTech Connect

    Morrison, W.H. III; Akin, D.E. )

    1990-03-01

    Ozone has been used to pretreat agricultural byproducts with the aim of increasing nutritive value for ruminants. However, not all treatments with ozone result in enhanced digestibility, suggesting reaction products from ozone treatment of plants might inhibit rumen microbial activity. Coastal Bermuda grass (Cynodon dactylon L. Pers.) (CBG) and Kentucky-31 tall fescue (Festuca arundinacea Schreb.) (K-31) were treated with ozone and the water-soluble products determined. The following acids were identified: caproic, levulinic, p-hydroxybenzoic, vinillic, azelaic, and malonic. In addition, vanillin and p-hydroxybenzaldehyde were also identified. Ozone treatment of the cell walls of CBG produced mainly p-hydroxybenzoic acid, vanillic acid, azelaic acid, p-hydroxybenzaldehyde, and vanillin. Ozone treatment of K-31 cell walls produced levulinic acid in addition to those products found from CBG cell walls. The production of vanillin and p-hydroxybenzaldehyde, which have been shown to be especially toxic to rumen microorganisms, offers an explanation for the negative affects of ozone treatment on forage.

  19. 40 CFR 721.10390 - Acetoacetanilide reaction product with multifunctional acrylate (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... New Uses for Specific Chemical Substances § 721.10390 Acetoacetanilide reaction product with... chemical substance identified generically as acetoacetanilide reaction product with multifunctional... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Acetoacetanilide reaction product...

  20. 40 CFR 721.9514 - Ethyl silicate, reaction products with modified alkoxysilane salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.9514 Ethyl silicate, reaction products with.... (1) The chemical substance identified generically as Ethyl silicate, reaction products with modified... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Ethyl silicate, reaction products...

  1. 40 CFR 721.10570 - Cyclic amine reaction product with acetophenone and formaldehyde acid salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10570 Cyclic amine reaction product... subject to reporting. (1) The chemical substance identified generically as cyclic amine reaction product... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Cyclic amine reaction product...

  2. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... reaction product (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as Dimer acid/polymerized rosin amidoamine reaction product (PMN... amidoamine reaction product (generic). 721.9485 Section 721.9485 Protection of Environment...

  3. 40 CFR 721.10445 - 2-Propen-1-ol, reaction products with hydrogen sulfide, distn. residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10445 2-Propen-1-ol, reaction products with...) The chemical substance identified as 2-propen-1-ol, reaction products with hydrogen sulfide, distn... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 2-Propen-1-ol, reaction products...

  4. 40 CFR 721.10428 - Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., reaction products with 1-piperazineethanamine. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as fatty acids, C18-unsatd., dimers, reaction products with..., reaction products with 1-piperazineethanamine. 721.10428 Section 721.10428 Protection of...

  5. 40 CFR 721.10390 - Acetoacetanilide reaction product with multifunctional acrylate (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... New Uses for Specific Chemical Substances § 721.10390 Acetoacetanilide reaction product with... chemical substance identified generically as acetoacetanilide reaction product with multifunctional... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Acetoacetanilide reaction product...

  6. 40 CFR 721.9514 - Ethyl silicate, reaction products with modified alkoxysilane salt (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.9514 Ethyl silicate, reaction products with.... (1) The chemical substance identified generically as Ethyl silicate, reaction products with modified... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Ethyl silicate, reaction products...

  7. 40 CFR 721.3805 - Formaldehyde, reaction products with 1,3-benzenedimethanamine and bisphenol A.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.3805 Formaldehyde, reaction products... to reporting. (1) The chemical substance identified as formaldehyde, reaction products with 1,3... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Formaldehyde, reaction products with...

  8. 40 CFR 721.10570 - Cyclic amine reaction product with acetophenone and formaldehyde acid salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10570 Cyclic amine reaction product... subject to reporting. (1) The chemical substance identified generically as cyclic amine reaction product... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Cyclic amine reaction product...

  9. 40 CFR 721.10428 - Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., reaction products with 1-piperazineethanamine. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as fatty acids, C18-unsatd., dimers, reaction products with..., reaction products with 1-piperazineethanamine. 721.10428 Section 721.10428 Protection of...

  10. 40 CFR 721.10445 - 2-Propen-1-ol, reaction products with hydrogen sulfide, distn. residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10445 2-Propen-1-ol, reaction products with...) The chemical substance identified as 2-propen-1-ol, reaction products with hydrogen sulfide, distn... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 2-Propen-1-ol, reaction products...