Formation of nitric oxide and nitrous oxide in electron-irradiated H218O/N2 ice mixtures—evidence for the existence of free oxygen atoms in interstellar and solar system analog ices

2011 ◽  
Vol 13 (35) ◽  
pp. 15749 ◽  
Author(s):  
Weijun Zheng ◽  
Y. Seol Kim ◽  
Ralf I. Kaiser
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Solar System ◽  
Free Oxygen ◽  
Oxygen Atoms

Temperature dependence of rate constants for the reactions of oxygen atoms, O(3P), with HBr and HI

1978 ◽  
Vol 56 (23) ◽  
pp. 2934-2939 ◽  
Author(s):  
D. L. Singleton ◽  
R. J. Cvetanović
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Standard Deviation ◽  
Phase Shift ◽  
Rate Constants ◽  
Bond Energy ◽  
Bond Order ◽  
Shift Technique ◽  
Decomposition Of Nitrous Oxide ◽  
Oxygen Atoms

Rate constants for the reactions O(3P) + HX → OH + X (X = Br, I) have been determined by a phase shift technique. Oxygen atoms were generated by modulated mercury photosensitized decomposition of nitrous oxide, and were monitored by the chemiluminescence from the reaction with nitric oxide. Over the temperature interval 298–554 K, the rate constants are satisfactorily represented by the Arrhenius expressions kO+HBr = (8.09 ± 0.86) × 109 exp (−3.59 ± 0.08)/RT and kO+HI = (2.82 ± 0.27) × 1010 exp (−1.99 ± 0.07)/RT, where the units are ℓ mol−1 s−1 and kcal mol−1. The indicated uncertainties are one standard deviation. The results of bond energy–bond order calculations, incorporating recently proposed modifications, are discussed.

THE EFFECT OF MOLECULAR OXYGEN ON THE REACTION OF OXYGEN ATOMS WITH cis-2-PENTENE

1959 ◽  
Vol 37 (5) ◽  
pp. 953-965 ◽  
Author(s):  
S. Sato ◽  
R. J. Cvetanović
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Nitrogen Dioxide ◽  
Molecular Oxygen ◽  
Reaction Mechanisms ◽  
Room Temperature ◽  
Pressure Independent ◽  
Decomposition Of Nitrous Oxide ◽  
Oxygen Atoms

The effect of the presence of nitrogen, oxygen, and nitric oxide on the reaction between cis-2-pentene and oxygen atoms has been investigated at room temperature (25 ± 2 °C). For production of oxygen atoms use was made of mercury-photosensitized decomposition of nitrous oxide and of the photolysis of nitrogen dioxide at 3660 Å.In the N2O work, the presence of molecular oxygen induced the formation of acetaldehyde, propanal, methanol, and ethanol. In the NO2 work, the amounts of acetaldehyde, propanal, and ethyl nitrate formed increased rapidly with increasing pressure of molecular oxygen. Possible reaction mechanisms for the formation of these compounds are discussed.Additional information was obtained on the pressure-independent fragmentation in the reaction of oxygen atoms with cis-2-pentene.

Arrhenius parameters for the reactions of O(3P) atoms with several aldehydes and the trend in aldehydic C—H bond dissociation energies

1977 ◽  
Vol 55 (18) ◽  
pp. 3321-3327 ◽  
Author(s):  
D. L. Singleton ◽  
R. S. Irwin ◽  
R. J. Cvetanović
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Ground State ◽  
Hydrogen Abstraction ◽  
Bond Dissociation Energies ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Shift Technique ◽  
Decomposition Of Nitrous Oxide ◽  
Oxygen Atoms

The phase-shift technique has been used to determine the temperature dependence of the reaction of ground state oxygen atoms with several aldehydes. Oxygen atoms were generated by modulated photosensitized decomposition of nitrous oxide and were monitored by the chemiluminescence from their reaction with nitric oxide. The Arrhenius expressions determined over the temperature interval 298–472 K are: k1 (acetaldehyde) = (7.21 ± 1.49) × 109 exp (−1960 ± 153/RT); k1(propionaldehyde) = (7.78 ± 0.75) × 109 exp (−1727 ± 66/RT); k1(butyralde-hyde) = (9.99 ± 0.56) × 109 exp (−1702 ± 40/RT); k1(isobutyraldehyde) = (7.92 ± 1.02) × 109 exp (−1445 ± 91/RT), where the units are ℓ mol−1 s−1 and cal mol−1. The indicated uncertainties are one standard deviation. After small corrections were made for the potential abstraction of alkyl hydrogens, the activation energies of aldehydic hydrogen abstraction were used to estimate the aldehydic C—H bond dissociation energies, D(RCO—H). The trend of slightly decreasing values of D(RCO—H) thus obtained for the sequence H2CO, CH3CHO, C2H5CHO, n-C3H7CHO, i-C3H7CHO was also indicated by the aldehydic C—H stretching frequencies.

Emissions of nitrous oxide and nitric oxide associated with the decomposition of arable crop residues on a sandy loam soil in Eastern England

Agronomie ◽  
2002 ◽  
Vol 22 (7-8) ◽  
pp. 731-738 ◽  
Author(s):  
Roland Harrison ◽  
Sharon Ellis ◽  
Roy Cross ◽  
James Harrison Hodgson
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Crop Residues ◽  
Sandy Loam ◽  
Sandy Loam Soil ◽  
Arable Crop ◽  
Loam Soil

The complete denitrification pathway of the symbiotic, nitrogen-fixing bacterium Bradyrhizobium japonicum

2005 ◽  
Vol 33 (1) ◽  
pp. 141-144 ◽  
Author(s):  
E.J. Bedmar ◽  
E.F. Robles ◽  
M.J. Delgado
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Bradyrhizobium Japonicum ◽  
Mutational Analysis ◽  
Control Level ◽  
Gene Clusters ◽  
Alternative Form ◽  
Nitrate Respiration ◽  
Regulatory Cascade ◽  
Denitrification Genes

Denitrification is an alternative form of respiration in which bacteria sequentially reduce nitrate or nitrite to nitrogen gas by the intermediates nitric oxide and nitrous oxide when oxygen concentrations are limiting. In Bradyrhizobium japonicum, the N2-fixing microsymbiont of soya beans, denitrification depends on the napEDABC, nirK, norCBQD, and nosRZDFYLX gene clusters encoding nitrate-, nitrite-, nitric oxide- and nitrous oxide-reductase respectively. Mutational analysis of the B. japonicum nap genes has demonstrated that the periplasmic nitrate reductase is the only enzyme responsible for nitrate respiration in this bacterium. Regulatory studies using transcriptional lacZ fusions to the nirK, norCBQD and nosRZDFYLX promoter region indicated that microaerobic induction of these promoters is dependent on the fixLJ and fixK2 genes whose products form the FixLJ–FixK2 regulatory cascade. Besides FixK2, another protein, nitrite and nitric oxide respiratory regulator, has been shown to be required for N-oxide regulation of the B. japonicum nirK and norCBQD genes. Thus nitrite and nitric oxide respiratory regulator adds to the FixLJ–FixK2 cascade an additional control level which integrates the N-oxide signal that is critical for maximal induction of the B. japonicum denitrification genes. However, the identity of the signalling molecule and the sensing mechanism remains unknown.

scholarly journals Crystal structure of 2-methyl-1H-imidazol-3-ium aquatrichlorido(oxalato-κ2O,O′)stannate(IV)

2015 ◽  
Vol 71 (5) ◽  
pp. 520-522 ◽  
Author(s):  
Mouhamadou Birame Diop ◽  
Libasse Diop ◽  
Laurent Plasseraud ◽  
Thierry Maris
Keyword(s):  
Hydrogen Bonds ◽  
Water Molecule ◽  
Three Dimensional ◽  
Free Oxygen ◽  
Coordination Environment ◽  
Dimensional Network ◽  
Oxalate Ligand ◽  
Distorted Octahedral ◽  
Distorted Octahedral Coordination Environment ◽  
Oxygen Atoms

The tin(IV) atom in the complex anion of the title salt, (C4H7N2)[Sn(C2O4)Cl3(H2O)], is in a distorted octahedral coordination environment defined by three chlorido ligands, an oxygen atom from a water molecule and two oxygen atoms from a chelating oxalate anion. The organic cation is linked through a bifurcated N—H...O hydrogen bond to the free oxygen atoms of the oxalate ligand of the complex [Sn(H2O)Cl3(C2O4)]−anion. Neighbouring stannate(IV) anions are linked through O—H...O hydrogen bonds involving the water molecule and the two non-coordinating oxalate oxygen atoms. In combination with additional N—H...Cl hydrogen bonds between cations and anions, a three-dimensional network is spanned.

scholarly journals Emissions of Nitrous Oxide and Nitric Oxide from Soils of Native and Exotic Ecosystems of the Amazon and Cerrado Regions of Brazil

2001 ◽  
Vol 1 ◽  
pp. 312-319 ◽  
Author(s):  
Eric A. Davidson ◽  
Mercedes M.C. Bustamante ◽  
Alexandre de Siqueira Pinto
Keyword(s):  
Nitric Oxide ◽  
Land Use ◽  
Nitrous Oxide ◽  
Photochemical Reactions ◽  
N2o Emissions ◽  
Secondary Forests ◽  
Soil Emissions ◽  
Amazonian Forests ◽  
The Impact ◽  
No Emissions

This paper reviews reports of nitrous oxide (N2O) and nitric oxide (NO) emissions from soils of the Amazon and Cerrado regions of Brazil. N2O is a stable greenhouse gas in the troposphere and participates in ozone-destroying reactions in the stratosphere, whereas NO participates in tropospheric photochemical reactions that produce ozone. Tropical forests and savannas are important sources of atmospheric N2O and NO, but rapid land use change could be affecting these soil emissions of N oxide gases. The five published estimates for annual emissions of N2O from soils of mature Amazonian forests are remarkably consistent, ranging from 1.4 to 2.4 kg N ha–1 year–1, with a mean of 2.0 kg N ha–1 year–1. Estimates of annual emissions of NO from Amazonian forests are also remarkably similar, ranging from 1.4 to 1.7 kg N ha–1 year–1, with a mean of 1.5 kg N ha–1 year–1. Although a doubling or tripling of N2O has been observed in some young (<2 years) cattle pastures relative to mature forests, most Amazonian pastures have lower emissions than the forests that they replace, indicating that forest-topasture conversion has, on balance, probably reduced regional emissions slightly (<10%). Secondary forests also have lower soil emissions than mature forests. The same patterns apply for NO emissions in Amazonia. At the only site in Cerrado where vegetation measurements have been made N2O emissions were below detection limits and NO emissions were modest (~0.4 kg N ha–1 year–1). Emissions of NO doubled after fire and increased by a factor of ten after wetting dry soil, but these pulses lasted only a few hours to days. As in Amazonian pastures, NO emissions appear to decline with pasture age. Detectable emissions of N2O have been measured in soybean and corn fields in the Cerrado region, but they are modest relative to fluxes measured in more humid tropical agricultural regions. No measurements of NO from agricultural soils in the Cerrado region have been made, but we speculate that they could be more important than N2O emissions in this relatively dry climate. While a consistent pattern is emerging from these studies in the Amazon region, far too few data exist for the Cerrado region to assess the impact of land use changes on N oxide emissions.

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