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Theoretical and experimental study of peroxy and alkoxy radicals in the NO3-initiated oxidation of isoprene. Phys Chem Chem Phys 2021; 23:5496-5515. [DOI: 10.1039/d0cp06267g] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Under atmospheric conditions, nitrate-RO2 radicals are equilibrated and react predominantly with HO2, RO2 and NO. The nitrate-RO chemistry is affected strongly by ring closure to epoxy radicals, impeding formation of MVK/MACR.
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Products and mechanism of the OH-initiated photo-oxidation of perfluoro ethyl vinyl ether, C 2F 5OCF[double bond, length as m-dash]CF 2. Phys Chem Chem Phys 2018; 20:11306-11316. [PMID: 29637965 DOI: 10.1039/c8cp01392f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The OH-initiated photo-oxidation of perfluoro ethyl vinyl ether (C2F5OCF[double bond, length as m-dash]CF2, PEVE) in air (298 K, 50 and 750 Torr total pressure) was studied in a photochemical reactor using in situ detection of PEVE and its products by Fourier transform IR absorption spectroscopy. The relative rate technique was used to derive the rate coefficient, k1, for the reaction of PEVE with OH as k1 = (2.8 ± 0.3) × 10-12 cm3 molecule-1 s-1. The photo-oxidation of PEVE in the presence of NOx at 1 bar results in formation of C2F5OCFO, FC(O)C(O)F and CF2O in molar yields of 0.50 ± 0.07, 0.46 ± 0.07 and 1.50 ± 0.22, respectively. FC(O)C(O)F and CF2O are formed partially in secondary, most likely heterogeneous processes. At a reduced pressure of 50 Torr, the product distribution is shifted towards formation of FC(O)C(O)F, indicating the important role of collisional quenching of initially formed association complexes, and enabling details of the reaction mechanism to be elucidated. An atmospheric photo-oxidation mechanism for PEVE is presented and the environmental implications of PEVE release and degradation are discussed.
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Absolute and relative-rate measurement of the rate coefficient for reaction of perfluoro ethyl vinyl ether (C 2F 5OCF[double bond, length as m-dash]CF 2) with OH. Phys Chem Chem Phys 2018; 20:3761-3767. [PMID: 29349468 DOI: 10.1039/c7cp08056e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The rate coefficient (k1) for the reaction of OH radicals with perfluoro ethyl vinyl ether (PEVE, C2F5OCF[double bond, length as m-dash]CF2) has been measured as a function of temperature (T = 207-300 K) using the technique of pulsed laser photolysis with detection of OH by laser-induced fluorescence (PLP-LIF) at pressures of 50 or 100 Torr N2 bath gas. In addition, the rate coefficient was measured at 298 K and in one atmosphere of air by the relative-rate technique with loss of PEVE and reference reactant monitored in situ by IR absorption spectroscopy. The rate coefficient has a negative temperature dependence which can be parameterized as: k1(T) = 6.0 × 10-13 exp[(480 ± 38/T)] cm3 molecule-1 s-1 and a room temperature value of k1 (298 K) = (3.0 ± 0.3) × 10-12 cm3 molecule-1 s-1. Highly accurate rate coefficients from the PLP-LIF experiments were achieved by optical on-line measurements of PEVE and by performing the measurements at two different apparatuses. The large rate coefficient and the temperature dependence indicate that the reaction proceeds via OH addition to the C[double bond, length as m-dash]C double bond, the high pressure limit already being reached at 50 Torr N2. Based on the rate coefficient and average OH levels, the atmospheric lifetime of PEVE was estimated to be a few days.
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Adsorption isotherms for hydrogen chloride (HCl) on ice surfaces between 190 and 220 K. Phys Chem Chem Phys 2016; 18:13799-810. [PMID: 27142478 DOI: 10.1039/c6cp01962e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The interaction of hydrogen chloride (HCl) with ice surfaces at temperatures between 190 and 220 K was investigated using a coated-wall flow-tube connected to a chemical ionization mass spectrometer. Equilibrium surface coverages of HCl were determined at gas phase concentrations as low as 2 × 10(9) molecules cm(-3) (∼4 × 10(-8) Torr at 200 K) to derive Langmuir adsorption isotherms. The data are described by a temperature independent partition coefficient: KLang = (3.7 ± 0.2) × 10(-11) cm(3) molecule(-1) with a saturation surface coverage Nmax = (2.0 ± 0.2) × 10(14) molecules cm(-2). The lack of a systematic dependence of KLang on temperature contrasts the behaviour of numerous trace gases which adsorb onto ice via hydrogen bonding and is most likely related to the ionization of HCl at the surface. The results are compared to previous laboratory studies, and the equilibrium partitioning of HCl to ice surfaces under conditions relevant to the atmosphere is evaluated.
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Correction: Kinetics and mechanism of the reaction of perfluoro propyl vinyl ether (PPVE, C3F7OCH[double bond, length as m-dash]CH2) with OH: assessment of its fate in the atmosphere. Phys Chem Chem Phys 2015. [PMID: 26205319 DOI: 10.1039/c5cp90133b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Correction for 'Kinetics and mechanism of the reaction of perfluoro propyl vinyl ether (PPVE, C3F7OCH[double bond, length as m-dash]CH2) with OH: assessment of its fate in the atmosphere' by D. Amedro et al., Phys. Chem. Chem. Phys., 2015, 17, 18558-18566.
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Kinetics and mechanism of the reaction of perfluoro propyl vinyl ether (PPVE, C₃F₇OCH=CH₂) with OH: assessment of its fate in the atmosphere. Phys Chem Chem Phys 2015; 17:18558-66. [PMID: 26112907 DOI: 10.1039/c5cp02233a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Absolute rate coefficients for the reaction between OH radicals and perfluoro propyl vinyl ether (PPVE) were obtained using the technique of pulsed laser photolysis with the detection of OH radicals by laser induced fluorescence. Rate coefficients were measured over a range of temperatures (212-298 K) and at either 50 or 200 Torr bath-gas (N2 or N2/O2). The temperature dependence of the rate coefficient is given by k1(212-298 K) = (4.88 ± 0.49) × 10(-13) exp[(564 ± 10)/T] cm(3) molecule(-1) s(-1) with a value at room temperature of (3.4 ± 0.3) × 10(-12) cm(3) molecule(-1) s(-1). No pressure dependence was observed, indicating that the reaction is at the high pressure limit under atmospheric conditions. The accuracy of the rate coefficient obtained was enhanced by on-line optical absorption measurements of PPVE at 184.95 nm using a value of σ(184.95 nm) = (5.64 ± 0.28) × 10(-18) cm(2) molecule(-1) determined in this work. An atmospheric lifetime of a few days for PPVE was calculated. Extensive quantum chemical calculations as a complement to the experimental work are presented in order to determine its probable tropospheric degradation mechanism.
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Theoretical study of the OH-initiated atmospheric oxidation mechanism of perfluoro methyl vinyl ether, CF3OCFCF2. Phys Chem Chem Phys 2015; 17:28697-704. [DOI: 10.1039/c5cp04839g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The fluorinated product glycolaldehyde can be catalytically converted to glyoxal + HF by H2O.
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Direct kinetic study of OH and O3 formation in the reaction of CH3C(O)O2 with HO2. J Phys Chem A 2014; 118:974-85. [PMID: 24491030 DOI: 10.1021/jp412380z] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction between HO2 and CH3C(O)O2 has three exothermic product channels, forming OH (R3a), peracetic acid (R3b), and acetic acid plus O3 (R3c). The branching ratios of the OH- and ozone-forming reaction channels were determined using a combination of laser-induced fluorescence (LIF, for time-resolved OH concentration measurement) and transient absorption spectroscopy (TAS, for time-resolved O3 concentration measurement) following pulsed laser generation of HO2 and CH3C(O)O2 from suitable precursors. TAS was also used to determine the initial concentration of the reactant peroxy radicals. The data were evaluated by numerical simulation using kinetic models of the measured concentration profiles; a Monte Carlo approach was used to estimate the uncertainties of the rate constants (k3) and branching ratios (α) thus obtained. The reaction channel forming OH (R3a) was found to be the most important with α3a = 0.61 ± 0.09 and α3c = 0.16 ± 0.08. The overall rate coefficient of the title reaction was found to be k3 = (2.1 ± 0.4) × 10(-11) cm(3) molecule(-1) s(-1) for both HO2 and DO2. Use of DO2 resulted in an increase in α3a to 0.80 ± 0.14. Comparison with former studies shows that OH formation via (R3) has been underestimated significantly to date. Possible reasons for these discrepancies and atmospheric implications are discussed.
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Pressure dependent OH yields in the reactions of CH3CO and HOCH2CO with O2. Phys Chem Chem Phys 2014; 16:10990-8. [DOI: 10.1039/c4cp01108b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Pressure dependent photolysis quantum yields for CH3C(O)CH3 at 300 and 308 nm and at 298 and 228 K. Phys Chem Chem Phys 2013; 15:10500-9. [DOI: 10.1039/c3cp50291k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Kinetics and mechanism of the heterogeneous reaction of N2O5 with mineral dust particles. Phys Chem Chem Phys 2012; 14:8551-61. [DOI: 10.1039/c2cp40805h] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Rate coefficients for the reactions CH3 + Br2 (224-358 K), CH3CO + Br2 (228 and 298 K), and Cl + Br2 (228 and 298 K). INT J CHEM KINET 2010. [DOI: 10.1002/kin.20505] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Photolysis of CH3C(O)CH3 at 248 and 266 nm: pressure and temperature dependent overall quantum yields. Phys Chem Chem Phys 2009; 11:6173-81. [DOI: 10.1039/b904130c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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15
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Interaction of formic and acetic acid with ice surfaces between 187 and 227 K. Investigation of single species- and competitive adsorption. Phys Chem Chem Phys 2008; 10:2345-55. [DOI: 10.1039/b800831k] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Photolysis of CH3C(O)CH3 (248 nm, 266 nm), CH3C(O)C2H5 (248 nm) and CH3C(O)Br (248 nm): pressure dependent quantum yields of CH3 formation. Phys Chem Chem Phys 2007; 9:4098-113. [PMID: 17687461 DOI: 10.1039/b701382e] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation of CH(3) in the 248 or 266 nm photolysis of acetone (CH(3)C(O)CH(3)), 2-butanone (methylethylketone, MEK, CH(3)C(O)C(2)H(5)) and acetyl bromide (CH(3)C(O)Br) was examined using the pulsed photolytic generation of the radical and its detection by transient absorption spectroscopy at 216.4 nm. Experiments were carried out at room temperature (298 +/- 3 K) and at pressures between approximately 5 and 1500 Torr N(2). Quantum yields for CH(3) formation were derived relative to CH(3)I photolysis at the same wavelength in back-to-back experiments. For acetone at 248 nm, the yield of CH(3) was greater than unity at low pressures (1.42 +/- 0.15 extrapolated to zero pressure) confirming that a substantial fraction of the CH(3)CO co-product can dissociate to CH(3) + CO under these conditions. At pressures close to atmospheric the quantum yield approached unity, indicative of almost complete collisional relaxation of the CH(3)CO radical. Measurements of increasing CH(3)CO yield with pressure confirmed this. Contrasting results were obtained at 266 nm, where the yields of CH(3) (and CH(3)CO) were close to unity (0.93 +/- 0.1) and independent of pressure, strongly suggesting that nascent CH(3)CO is insufficiently activated to decompose on the time scales of these experiments at 298 K. In the 248 nm photolysis of CH(3)C(O)Br, CH(3) was observed with a pressure independent quantum yield of 0.92 +/- 0.1 and CH(3)CO remained below the detection limit, suggesting that CH(3)CO generated from CH(3)COBr photolysis at 248 nm is too highly activated to be quenched by collision. Similar to CH(3)C(O)CH(3), the photolysis of CH(3)C(O)C(2)H(5) at 248 nm revealed pressure dependent yields of CH(3), decreasing from 0.45 at zero pressure to 0.19 at pressures greater than 1000 Torr with a concomitant increase in the CH(3)CO yield. As part of this study, the absorption cross section of CH(3) at 216.4 nm (instrumental resolution of 0.5 nm) was measured to be (4.27 +/- 0.2) x 10(-17) cm(2) molecule(-1) and that of C(2)H(5) at 222 nm was (2.5 +/- 0.6) x 10(-18) cm(2) molecule(-1). An absorption spectrum of gas-phase CH(3)C(O)Br (210-305 nm) is also reported for the first time.
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Abstract
The heterogeneous chemistry of HOI, ICl and IBr on sea salt and sea salt proxies has been studied at 274 K using two experimental approaches: a wetted wall flow tube coupled to an electron impact mass spectrometer (WWFT-MS) and an aerosol flow tube (AFT) coupled to a differential mobility analyser (DMA) and a chemical ionisation mass spectrometer (CIMS). Uptake of all three title molecules into bulk aqueous halide salt films was rapid and controlled by gas phase diffusion. Uptake of HOI gave rise to gas-phase ICl and IBr, with the latter being the predominant product whenever Br(-) was present. Only partial release of IBr was observed due to high solubility of dihalogens in the film. ICl uptake gave the same yield of IBr as HOI uptake. Uptake of ICl on NaBr aerosol was accommodation limited with alpha = 0.018 +/- 0.004 and gas phase IBr product has a yield of 0.6 +/- 0.3. The results show that HOI can act as a catalyst for activation of bromine from sea-salt aerosols in the marine boundary layer, via the reactions: HOI(aq) + Cl + H--> ICl(aq) + H(2)O(l) and ICl(aq) + Br--> IBr(aq) + Cl.
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Abstract
Pulsed laser photolysis combined with transient absorption spectroscopy and resonance fluorescence was used to examine the photolysis of OIO at a number of wavelengths corresponding to absorption bands in its visible spectrum between approximately 530 and 570 nm. Photolysis at 532 nm was found to result in substantial depopulation of the absorbing ground state, enabling an estimate for the absorption cross section of OIO at 610.2 nm of (6 +/- 2) x 10(-18) cm2 molecule(-1) to be obtained. No evidence was found for I atom formation following photolysis of OIO at 532, 562.3, 567.9 and 573.8 nm, enabling an upper limit to the I atom quantum yield of < 0.05 (560-580 nm) and < 0.24 (532 nm) to be established.
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Influence of summertime deep convection on formaldehyde in the middle and upper troposphere over Europe. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jd007001] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Kinetics of the reactions of HO with methanol (210–351 K) and with ethanol (216–368 K). Phys Chem Chem Phys 2005; 7:349-55. [DOI: 10.1039/b413961e] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Reaction of O(3P) with the alkyl iodides: CF3I, CH3I, CH2I2, C2H5I, 1-C3H7I and 2-C3H7I. Phys Chem Chem Phys 2004. [DOI: 10.1039/b316402k] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Reaction of HO and DO with 2-vinylfuran. Phys Chem Chem Phys 2003. [DOI: 10.1039/b307696b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Interaction of methanol, acetone and formaldehyde with ice surfaces between 198 and 223 K. Phys Chem Chem Phys 2002. [DOI: 10.1039/b206258e] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Temperature Dependence of the Product Branching Ratios of the ClO Self-Reaction in Oxygen. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100097a019] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Methylperoxy self-reaction: products and branching ratio between 223 and 333 K. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100384a040] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Heterogeneous Reactivity of Gaseous Nitric Acid on Al2O3, CaCO3, and Atmospheric Dust Samples: A Knudsen Cell Study. J Phys Chem A 2001. [DOI: 10.1021/jp001254+] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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The position dependent 15N enrichment of nitrous oxide in the stratosphere. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2001; 37:91-95. [PMID: 11761405 DOI: 10.1080/10256010108033285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The position dependent 15N fractionation of nitrous oxide (N2O), which cannot be obtained from mass spectrometric analysis on molecular N2O itself, can be determined with high precision using isotope ratio mass spectrometry on the NO+ fragment that is formed on electron impact in the source of an isotope ratio mass spectrometer. Laboratory UV photolysis experiments show that strong position dependent 15N fractionations occur in the photolysis of N2O in the stratosphere, its major atmospheric sink. Measurements on the isotopic composition of stratospheric N2O indeed confirm the presence of strong isotope enrichments, in particular the difference in the fractionation constants for 15N14NO and 14N15NO. The absolute magnitudes of the fractionation constants found in the stratosphere are much smaller, however, than those found in the lab experiments, demonstrating the importance of dynamical and also additional chemical processes like the reaction of N2O with O(1D).
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Reaction of HO2 with ClO: Flow Tube Studies of Kinetics and Product Formation between 215 and 298 K. J Phys Chem A 2000. [DOI: 10.1021/jp9924631] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sequential Two (Blue) Photon Absorption by NO2 in the Presence of H2 as a Source of OH in Pulsed Photolysis Kinetic Studies: Rate Constants for Reaction of OH with CH3NH2, (CH3)2NH, (CH3)3N, and C2H5NH2 at 295 K. J Phys Chem A 1998. [DOI: 10.1021/jp9821937] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Mass-independent oxygen isotope fractionation in atmospheric CO as a result of the reaction CO + OH. Science 1998; 281:544-6. [PMID: 9677193 DOI: 10.1126/science.281.5376.544] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Atmospheric carbon monoxide (CO) exhibits mass-independent fractionation in the oxygen isotopes. An 17O excess up to 7.5 per mil was observed in summer at high northern latitudes. The major source of this puzzling fractionation in this important trace gas is its dominant atmospheric removal reaction, CO + OH --> CO2 + H, in which the surviving CO gains excess 17O. The occurrence of mass-independent fractionation in the reaction of CO with OH raises fundamental questions about kinetic processes. At the same time the effect is a useful marker for the degree to which CO in the atmosphere has been reacting with OH.
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Application of a Gaussian Distribution Function To Describe Molecular UV−Visible Absorption Continua. 2. The UV Spectra of RO2• Radicals. J Phys Chem A 1997. [DOI: 10.1021/jp961715k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Optical detection of NO3 and NO2 in ?pure? HNO3 vapor, the liquid-phase decomposition of HNO3. INT J CHEM KINET 1993. [DOI: 10.1002/kin.550250910] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Abstract
Hydrocephalus complicated the clinical course of four patients with pituitary adenoma. In three it was noted late, long after surgical intervention and radiotherapy had been carried out. In one patient, hydrocephalus was part of the presenting syndrome. The differential diagnosis of hypopituitarism and occult hydrocephalus is difficult. The possibility of hydrocephalus complicating a pituitary adenoma constitutes another indication for arteriography before carrying out definitive treatment, or should the clinical course be unsatisfactory at any time.
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Abstract
✓ A patient with severe brain injury began vomiting 12 weeks after admission. This magnified a progressive weight loss of 34 kg. Vascular compression of the duodenum was confirmed as the cause of the vomiting. With hyperalimentation, vomiting stopped and weight gain occurred. This easily reversible syndrome should be considered in the differential diagnosis of vomiting in brain-injured patients with weight loss.
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