- OZONE GENERATION IN THE 214-nm PHOTOLYSIS OF OXYGEN AT 25 degree C.
-
Ozone formation in the 214-mm photolysis of oxygen at pressures ranging from 380 to 1300 Torr was investigated. The rates of ozone formation increase with the square of oxygen pressure mirroring the pressure dependence of the absorption cross sections of oxygen. This observation demonstrates the importance of the collision-induced changes in oxygen absorbance and points to a need to examine the role of oxygen dimer (O//2)//2 in reactions initiated by its photodissociation. Because of the high dilution of ozone, its formation was found to be linear with time even though, on the average, its rate of photolysis exceeded the rate of its generation from oxygen. The quantum yield of ozone formation was 1. 86 plus or minus 0. 17 independent of O//2 pressure.
- Horowitz,Von Helden,Simon,Crutzen,Moortgat
-
-
Read Online
- Kinetics and products of the reaction O2(1σ g+) with N2O
-
Previous studies have suggested that the reaction of O2O 2(1σg+) + N2O / NO + NO2 may be a significant source of NOx in the atmosphere if the branching ratio of this channel is greater than ?1%. We have measured the overall rate coefficient (k1) for the reaction of O 2O2(1σg+) with N2O to be k1(295 K) = (1.06±0.14)×10 -13 cm3 molecule-1 s-1 at 295 K and k1(T) = (7.48±1.66)×10-14 exp[(87±40).T] cm3 molecule-1 s-1 as a function of temperature over therange 210-370 K. The yields of NO, NO 2 or O3 that are possible reaction products from the title reaction were undetectably small. Also, the net loss of N2O from the title reaction was negligibly small. We report upper limits for the yields for the production of NOx, the production of O3 and the loss of N2O (all at 298 K) to be-4, -3, and-3,respectively. We conclude that the reaction of O2O2(1σ g+) + N2O is neither a significant source of NOx in the atmosphere nor a significant sink for N2O. by Oldenbourg Wissenschaftsverlag.
- Dunlea, Edward J.,Talukdar, Ranajit K.,Ravishankara
-
-
Read Online
- Electrosynthesis and physicochemical properties of PbO2 films
-
An electrochemical and X-ray diffraction study has been conducted on the formation of lead dioxide deposits on platinum, from nitric acid solutions, as a function of potential and temperature. It has been shown that these parameters strongly influence the morphology and electrocatalytic activity of the PbO2 films. The electrodeposition process is satisfactorily described by an electrochemical, chemical, electrochemical mechanism: (i) H2O → OHads + H+ + e-; (ii) Pb2+ + OHads → Pb(OH)2+; (iii) Pb(OH)2+ + H2O → PbO2 + 3H+ + e-; the second electron transfer stage and Pb2+ diffusion control the dioxide formation in the lower and higher overpotential range, respectively. Temperature and potential (or current) are important parameters in the electrodeposition process. Depending on the potential region, the process can be kinetically or diffusion controlled. In an acid electrolyte, where mainly the β-PbO2 modification is electrodeposited, the amount of α-phase impurity increases with increasing potential in the kinetically controlled region and decreases in the diffusion controlled domain. In addition, relatively low electrodeposition potentials and high temperatures favor an increase of the crystallite size with preferred crystallographic orientation for both α- and β-PbO2 modifications. The temperature of the growth solution affects the crystallinity of the resulting oxide deposits and has a marked effect on their performance as anodes in processes at high positive potentials such as ozone generation.
- Velichenko,Amadelli,Benedetti,Girenko,Kovalyov,Danilov
-
-
Read Online
- Systematic trends in the vibrational frequency shifts of some molecules trapped in amorphous water ice
-
This paper focuses on systematic examination of the vibrational frequency shifts of some molecules trapped in water ices. It is shown that for the bands, for which the laboratory taken data are available, the magnitude and the sign of a vibrational shift for the molecules trapped in water ice can be approximately predicted using empirical correlations with macroscopic properties of the host. These results can be useful for identification of the carriers of absorption in matrix spectroscopy, for the study of intermolecular interactions, for a number of applications involving remote spectroscopic sensing of molecular species in the atmosphere and in space.
- Vigasin,Schriver-Mazzuoli,Schriver
-
-
Read Online
- Synergistic effects of sonolysis combined with ozonolysis for the oxidation of azobenzene and methyl orange
-
The extent of mineralization, measured as total organic carbon (TOC) losses, during the 500 kHz sonication of azobenzene or methyl orange solutions increased from 20 to > 80% in the presence of O3. The abatement of the total organic load by the joint action of ultrasound and O2 amounted to chemical synergism. Since TOC losses were not enhanced by ozonation followed by sonication and ground-state oxygen atoms, synergism likely involved the fast oxidation by O3 of free radical or unsaturated species produced by ·OH radical attack on otherwise refractory products. Some of these products were possibly saturated mono- and dicarboxylic acids, known to be resistant to O3 oxidation. Benzoquinone and nitrobenzene were rapidly and completely mineralized by the combined oxidation treatment. Thus, direct ozonation of unsaturated sonolytic byproducts also accounted for part of the observed improvement of the extent of mineralization. The anomalous kinetic behavior of the sonochemical degradation of benzoquinone during the absence of O3 was accounted for by its high reactivity toward the inert HO2· and O2-· radicals.
- Destaillats, Hugo,Colussi,Joseph, Jiju M.,Hoffmann, Michael R.
-
-
Read Online
- Photochemical removal of NO, NO2, and N2O by 146 nm Kr2excimer lamp in N2 at atmospheric pressure
-
The photochemical removal of NO, N02, and N20 was investigated in N2 using a 146 nm Kr2 (25mWcm 2) excimer lamp. The results obtained were compared with those obtained using 172 nm Xe2 (50
- Tsuji, Masaharu,Kamo, Naohiro,Kawahara, Takashi,Kawahara, Masashi,Senda, Makoto,Hishinuma, Nobuyuki
-
-
Read Online
- Lattice oxygen of PbO2induces crystal facet dependent electrochemical ozone production
-
The on-site production of ozoneviaelectrochemical water electrolysis has attracted increasing interest because of its security and efficiency. However, the underlying mechanism of the facet effect and the influence of lattice oxygen on β-PbO2for electrochemical ozone production (EOP) remain unclear. Here, β-PbO2-120 nanorods (β-PbO2-120 NRs) were prepared to investigate the mechanism of the facet effect and the influence of lattice oxygen during the EOP process. The β-PbO2-120 NRs assembled as an anode in a membrane electrode assembly show a remarkable EOP performance. Measurements usingin situ18O isotope-labeling differential electrochemical mass spectrometry confirm that all three oxygen atoms in the ozone originate from the lattice oxygen of β-PbO2. Theoretical calculations verify that the EOP reaction pathway on β-PbO2follows the lattice oxygen mechanism (LOM), and surface lattice oxygen migration and coupling to O2/O3are favorable on the (101) and (110) surfaces of β-PbO2. Different reaction mechanisms are proposed on the two surfaces, and (101) exhibits higher reactivity for O2and the formation of O3. This valuable insight into the facet effect and LOM of metal oxide-based electrocatalysts can be extended to other applications.
- Jiang, Wenbin,Wang, Shibin,Liu, Jia,Zheng, Haiyang,Gu, Yu,Li, Wenwen,Shi, Huaijie,Li, Suiqin,Zhong, Xing,Wang, Jianguo
-
-
Read Online
- Conversion of SO2 to SO3 Facilitated by in Situ UV Photolysis of H2CO and SO2 in an O2 Matrix at 12 K
-
The photooxidation product distributions observed in photolyses of H2CO and H2CO*SO2 molecular complexes in O2 matrices at λ = 270-420 nm are compared.Photodissociation of H2CO produces RO2 species, i.e., HO2 and HC(O)OO radicals, which then efficiently oxidize SO2 to SO3 (and H2SO4).This process occurs with an efficiency of ca. 0.7 +/- 0.3 per H2CO*SO2 molecular complex photodissociated.Various photooxidation mechanisms are considered.Implications of the low-temperature/matrix photooxidation results on atmospheric photooxidation of SO2 by RO2 species are discussed.
- Green, Martina,Lee, Edward K. C.
-
-
Read Online
- Molecular-scale characterization of the reaction of ozone with decanethiol monolayers on Au(111)
-
The chemical reaction of ozone with decanethiol monolayers on Au(111) was characterized using X-ray photoelectron spectroscopy and scanning tunneling microscopy. Our results show that exposure to ozone results in oxidation of the thiol terminus. The reaction initiates at the domain boundary network of the alkanethiol monolayer and propagates into the domains. Above a threshold surface oxygen content, the monolayer converts to a two-dimensional fluid that can subsequently recrystallize to a commensurate monolayer of partially oxidized thiol. Further exposure to ozone results in conversion of the monolayer to a fluid phase and a 10% to 30% expansion of the Au lattice at the Au - thiol interface with concomitant formation of Au islands. Our results demonstrate that crystallographic defects in monolayer films can play an important role in their chemical reactions.
- Poirier, Gregory E.,Herne, Tonya M.,Miller, C. Cameron,Tarlov, Michael J.
-
-
Read Online
- Kinetics and Mechanism of the BrO+HO2 Reaction
-
Using the discharge flow-mass spectrometric technique, the kinetics and mechanism of the BrO+HO2 reaction have been investigated in the temperature range 233-344 K.With an excess of HO2 over BrO, the rate constant was found to be k1=(4.77+/-0.3
- Larichev, Michael,Maguin, Francoise,Bras, Georges Le,Poulet, Gilles
-
-
Read Online
- The effect of criegee-intermediate scavengers on the OH yield froni the reaction of ozone with 2-methylbut-2-ene
-
The yield of OH from the gas-phase reaction of ozone with 2-methylbut-2-ene has been measured in the presence of various molecules (H2O, SO2, butanone, and acetic acid) that can act as scavengers for the Criegee intermediates (CIs) formed in the reaction. No discernible difference is observed between experiments carried out in the presence and absence of these scavengers. The results indicate that the thermal decomposition of CIs that give OH radicals is fast compared with their bimolecular reaction with the scavengers under the conditions of the experiments. Combined with the results of a recent time-resolved study, upper limits (in units of cm3 molecule-1 s-1) were determined for the bimolecular reactions of the CI with H2O (1 × 10-16), SO2 (4 × 10-15), butanone (2 × 10-14), and acetic acid (1 × 10-14). The results imply that these reactions are too slow to inhibit OH formation in the ozonolysis of alkenes and that the currently recommended OH yields can be used in models of atmospheric chemistry.
- Johnson, David,Lewin, Alison G.,Marston, George
-
-
Read Online
- Reaction between the Amidogen Radical, .NH2, and Molecular Oxygen in Low-Temperature Matrices
-
The reaction between .NH2 and O2 has been examined in a low-temperature matrix for the first time.Results from a series of experiments employing isotopically substituted ammonia and oxygen indicate that the primary reaction products are HONO and H atoms.A reaction mechanism is proposed that involves the intermediacy of the aminoperoxy radical, NH2OO., which is stabilized by the low-temperature/high-pressure environment of the matrix before undergoing intramolecular decomposition or reaction with oxygen.
- Crowley, John N.,Sodeau, John R.
-
-
Read Online
- Infrared study of ozone adsorption on CeO2
-
Ozone (O3) adsorption on CeO2 pretreated under different conditions and characterized by low-temperature CO adsorption was studied by Fourier transform infrared (FTIR) spectroscopy at 77-300 K. Preliminary exposure to CO2, pyridine, acetonitrile, or methanol at 293 K or to CO at 77 K, as well as adsorption of 18O substituted O3 were used to clarify the nature of adsorption sites and the structure of the surface species. In O3 molecule is no longer symmetric but is bound to a surface Ce4+ ion via one of its terminal oxygen atoms. Basic surface sites of the samples pretreated at 773 K account for O3 decomposition, which occurs almost explosively at 77 K but could be inhibited if O3 adsorption is performed from the solution in liquid oxygen. Formation of ozonide O3- (bands at 792 and 772 cm-1) and superoxide O2- (band at 1128 cm-1) species was detected; these species are believed to be the intermediates of O3 decomposition on basic sites. On ceria, O3 does not react at 77 K with adsorbed CO, but ozonolysis of surface methoxy groups proceeds slowly, leading to a formate surface species.
- Bulanin,Lavalley,Lamotte,Mariey,Tsyganenko,Tsyganenko
-
-
Read Online
- An electrochemical and radiotracer investigation on lead dioxide: Influence of the deposition current and temperature
-
The properties of electrodeposited PbO2 are sensibly influenced by the deposition current and temperature. In particular, tritium radiotracer measurements demonstrated that protons were incorporated into the bulk of an oxide film and on its surface. The d
- Amadelli, Rossano,Samiolo, Luca,Velichenko, Aleksandr B.
-
-
Read Online
- Reactions of the IO? radical resulting in hydrogen atom abstraction from halogen-containing molecules
-
A jet-stream kinetic technique and the resonance fluorescence method applied to detection of iodine atoms were used to measure the rate constants of the reactions of the IO? radical with the halohydrocarbons CHFCl-CF2Cl (k = (3.2 ± 0.9) × 10-16 cm 3 molecule s-1) and CH2ClF (k = (9.4 ± 1.3) × 10-16 cm3 molecule s-1), the hydrogen-containing haloethers CF3-O-CH3 (k = (6.4 ± 0.9) × 10-16 cm3 molecule s-1) and CF3CH2-O-CHF2 (k = (1.2 ± 0.6) × 10-15 cm3 molecule s-1), and hydrogen iodide (k = (1.3 ± 0.9) × 10-12 cm3 molecule s-1) at 323 K.
- Larin,Spasskii,Trofimova,Turkin
-
-
Read Online
- Temperature dependent kinetics of the OH/HO2/O3 chain reaction by time-resolved IR laser absorption spectroscopy
-
The catalytic odd hydrogen (HOx) O3 cycle, OH + O3 → HO2 + O2 and HO2 + O3 → 2 O2 is one of the most important atmospheric processes leading to the natural destruction of atmospheric O3. This cycle is active at lower stratospheric altitudes (20-30 km, 190-230 K) in the mid-latitudes. The HOx chain reaction is estimated to be responsible for ~ 50% of the global O3 loss in the stratosphere. This makes it important to have accurate knowledge of the temperature dependent rate constants k1 and k2 for reliable modeling of atmospheric O3 phenomena. An extensive temperature dependent kinetic study of the catalytic HOx O3 cycle based on time-resolved, Doppler limited direct absorption spectroscopy of OH with a single mode (Δν = 0.0001/cm) high-resolution IR laser was presented. The sum of the two rate constants, k1 + k2, was measured at 190-315 K and can be accurately described by an Arrhenius-type expression (k1 + k2(cc/sec) = 2.26(40) x 10-12 exp[-976(50)/T]. These results agreed excellently with studies by Ravishanka et al. and Smith et al but were higher than the values currently accepted for atmospheric modeling. These studies reflected the first of such rate measurements to access the 190-230 K range relevant to kinetic modeling of O3 chain loss in the lower stratosphere.
- Nizkorodov, Sergey A.,Harper, Warren W.,Blackmon, Bradley W.,Nesbitt, David J.
-
-
Read Online
- Wavelength dependence of the primary ozone formation in high-pressure O2 and O2/CO2 mixtures under irradiation from 232 to 255 nm
-
Laser-induced reactions of O2 to yield ozone (O3) were investigated to estimate the quantum yield of primary odd-oxygen species production from photoabsorption by O2 as a function of excitation laser wavelength from 232 to 255 nm. The experiments were carried out at 35 °C in pressurized O2 (2.0 MPa) and O2/CO2 mixtures (9.6 MPa). The initial slope of O3 formation versus irradiation time was used to obtain the quantum yield of the primary odd-oxygen species, minimizing possible catalytic O3 production initiated by the subsequent photolysis of the product O3. The quantum yield of the primary odd-oxygen species was shown to be almost 2 in pressurized O2 at wavelengths shorter than 242 nm, i.e., the dissociation threshold of O2. It was less than 2 in the O2/CO2 mixture and seemed to have a tendency to increase slightly in the shorter-wavelength region. At wavelengths between 242 and 252 nm, the quantum yield decreased monotonically with increasing laser wavelength both in O2 and in O2/CO2 mixtures. It became almost 0 over the wavelength of 252 nm. These findings could not be explained by the contribution of the thermal energy of O2 in the photodissociation process alone. Although thermal dissociation of O2(A, A′, c) is not ruled out on the basis of the present experiments alone, the most likely mechanism is the thermal reaction of O2(A, A′, c) to produce O + O3, taking into account the temperature dependence experiments of Shi and Barker (J. Geophys. Res. 1992, 97, 13039).
- Sugimoto, Kazuko,Otomo, Junichiro,Koda, Seiichiro
-
-
Read Online
- Oxygen isotopic anomaly in surface induced ozone dissociation
-
The products of ozone dissociation occurring on glass surface are enriched in heavy oxygen isotopes (17O and 18O) in a mass independent (Δδ17O/Δδ18O = 1.0) fashion. Such behavior is in contrast to the case of thermal dissociation where fractionation is mass dependent (Δδ17O/Δδ18O = 0.5). Even photo-dissociation by visible light is a mass dependent process. The mass independent fractionation in surface dissociation can probably be explained by assuming that the dissociation takes place via a short-lived complex involving the ozone molecule and an active surface site. The anomalous isotopic fractionation in surface dissociation can be useful to decipher the mechanism of surface reaction in some cases.
- Chakraborty, Subrata,Bhattacharya
-
-
Read Online
- Kinetics of the Gas-Phase Reaction NO + NO3 --> 2NO2
-
The rate constant for the reaction NO + NO3 --> 2NO2 was measured over the temperature range of 209-414 K by using laser-induced fluorescence detection of NO3 in a flow tube reactor.Our recommended results are k(T) + (1.55 +/- 0.23) * 10-11 exp cm3 molecule-1 s-1 for T -11 cm3 molecule-1 s-1 for T > 300 K.These two expressions were required to describe the observed non-Arrhenius behavior of k(T).
- Hammer, Philip D.,Dlugokencky, Edward J.,Howard, Carleton J.
-
-
Read Online
- Ozone generation by rock fracture: Earthquake early warning?
-
We report the production of up to 10 ppm ozone during crushing and grinding of typical terrestrial crust rocks in air, O2 and CO2 at atmospheric pressure, but not in helium or nitrogen. Ozone is formed by exoelectrons emitted by high
- Baragiola, Raul A.,Dukes, Catherine A.,Hedges, Dawn
-
-
Read Online
- Dynamics of vibrationally excited ozone formed by three-body recombination. II. Kinetics and mechanism
-
Spectrally resolved infrared chemiluminescence from vibrationally excited ozone, O3 (ν), has been used to study the reaction kinetics of O3 (ν) in discharged O2/Ar mixtures at ca. 1 Torr and 80-150 K.Dependences of the excited state number densities on temperature and O2 mole fraction indicate O3 (ν) is formed primarily by three-body recombination of O with O2 and is destroyed by rapid chemical reaction with O.Several secondary excitation reactions involving vibrationally and electronically excited O2 are also indicated.The data are treated with a detailed steady-state analysis of the discharge kinetics, to extract estimates for rate coefficients of the key elementary reactions.The effective quasinascent state distribution in recombination is also inferred; this distribution shows selective recombination into the asymmetric stretching mode, but an apparently statistical (i.e., collisionally scrambled) behavior among the vibrational states within that mode.The results are discussed in terms of the detailed dynamics of three-body recombination.
- Rawlins, W. T.,Caledonia, G. E.,Armstrong, R. A.
-
-
Read Online
- Photochemical kinetics of vibrationally excited ozone produced in the 248 nm photolysis of O2/O3 mixtures
-
Infrared emission from vibrationally excited ozone was monitored as a function of time following pulsed laser photolysis of O3/O2 mixtures with total pressures from 300 to 1800 Torr at 295 K. The emission data obtained at 9.6 μm were analyzed by nonlinear least squares and by constructing χ2 surfaces. The results are entirely consistent with a conventional mechanism that includes the following reactions: (1a) O3 + hv → O(1D) + O2(a1Δ); (1b) O3 + hv → O(3P) + O2; (2a) O(1D) + O2 → O(3P) + O2(1Σg+); (2b) O(1D) + O2 → O(3P) + O2; (3) O(3P) + O2 + O2 → O3(v) + O2; (4) O3(v) + O2 → O3 + O2; (5a) O2(1Σg+) + O3 → O + O2 + O2; (5b) O2(1Σg+) + O3 → O3(v) + O2; (6) O2(1Σg+) + O2 → O2 + O2. There is no evidence for participation by ozone excited electronic states, but the reaction time scales are not well separated, leading to complexities in the analysis. The measured rate constants k3 (±σ) = (6.0 ± 1.1) × 10-34 cm6 s-1 and k5 (±σ) = (2.26 ± 0.15) × 10-11 cm3 s-1 are in good agreement with literature values. The phenomenological rate constant k4 (±σ) = (1.2 ± 0.2) × 10-11 cm3 s-1 is consistent with a model for vibrational deactivation. The measured value for the ratio k1ak2a/(k1k2) = 0.86 ± 0.13 is combined with a literature value for k1a/k1 to give an improved estimate for k2a/k2 = 0.95 (+0.05/-0.13).
- Green, Jack G.,Shi, Jichun,Barker, John R.
-
-
Read Online
- Concentration dependence of the spectroscopic and photochemical properties of atomic and molecular oxygen in argon matrices
-
Vacuum ultraviolet (VUV) excitation (200-100 nm) and visible emission (300-650 nm) spectra of O2 imbedded in Ar matrices at different concentrations are presented. At 0.1 and 0.2% concentrations a linear increase in the intensities of the excitation and emission spectra is observed. At these concentrations, photolysis of O2 is found to be negligible. At higher concentrations (0.5, 1 and 2%) the normalized intensities of the excitation and emission spectra of O2 decrease. With increasing concentration of O2 the permanent photolysis of O2 increases, which does not correlate, based on the excitation spectra of O in Ar, to the production of isolated O atoms. It has been shown that this anomalous behavior should be due to the formation of van der Waals dimers and oligomers at higher concentrations of O2 that upon photolysis produce ozone.
- Gudipati, Murthy S.,Schouren, Frank,Kalb, Martin,Wagner, Robert
-
-
Read Online
- Synergetic effect of pyrrolic-N and doped boron in mesoporous carbon for electrocatalytic ozone production
-
The exploration of highly efficient and inexpensive electrochemical ozone production (EOP) electrocatalysts for various in situ industrial applications is a recent hot topic in the catalysis field. In this work, B, N co-doped mesoporous carbon materials were designed and their EOP performance was predicted via density functional theory (DFT). In accordance with the theoretical predictions, a multifunctional site, pyrrolic-N, B co-doped defective mesoporous carbon (D-BNC) material with a high content of pyrrolic N, which exhibits excellent EOP electrocatalytic activity, was successfully synthesized. The high activity of D-BNC can be attributed to the synergetic effect played by pyrrolic-N, B, its neighboring C elements, and the defects. Furthermore, the five-membered cyclic structure formed between B and the neighboring C atoms which connects to O3 reduces the activation energy (0.41 eV) of the compound and promotes EOP. This work offers a new reference for the development of inexpensive metal free carbon-based electrocatalysts for EOP.
- Cao, Yongyong,Gu, Yu,Wang, Jianguo,Yan, Yilong,Yuan, Bowen,Zhang, Qiaoqiao,Zheng, Haiyang,Zhong, Xing
-
-
Read Online
- Products and mechanisms of the reaction of oleic acid with ozone and nitrate radical
-
The heterogeneous reactions of deposited, millimeter-sized oleic acid droplets with ozone and nitrate radicals are studied. Attenuated total reflectance infrared spectroscopy (ATR-IR), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS) are used for product identification and quantification. The condensed-phase products of the ozonolysis of oleic acid droplets are 1-nonanal (30 ± 3% carbon yield), 9-oxononanoic acid (14 ± 2%), nonanoic acid (7 ± 1%), octanoic acid (1 ± 0.2%), azelaic acid (6 ± 3%), and unidentified products. The infrared spectra show that a major fraction of the unidentified products contain an ester group. Additionally, the mass spectra show that at least some of the unidentified products have molecular weights greater than 1000 amu, which implicates a polymerization reaction. The observed steps of 172 amu (9-oxononanoic acid) and 188 amu (azelaic acid Criegee intermediate) in the mass spectra suggest that these species are the monomers in the condensed-phase polymerization reactions. 9-Oxononanoic acid is proposed to lengthen the molecular chain via secondary ozonide formation; the azelaic acid Criegee intermediate links molecules units via ester formation (specifically, α-acyloxyalkyl hydroperoxides). For the reaction of oleic acid with nitrate radicals, functional groups including -ONO2, -O 2NO2, and -NO2 are observed in the infrared spectra, and high molecular weight molecules are formed. Environmental scanning electron microscopy (ESEM) is employed to examine the hygroscopic properties of the oleic acid droplets before and after exposure to ozone or nitrate radical. After reaction, the droplets take up water at lower relative humidities compared to the unreacted droplets. The increased hygroscopic response may indicate that the oxidative aging of atmospheric organic aerosol particles has significant impact on radiative forcing. $ 2005 American Chemical Society.
- Hung, Hui-Ming,Katrib, Yasmine,Martin, Scot T.
-
-
Read Online
- Nucleation by Free Radicals from the Photooxidation of Sulfur Dioxide in Air
-
Previously reported experimental results of the production of condensation nuclei by the photooxidation of SO2 in air are reanalyzed on the basis that hte principal photochemical reaction of SO2 is SO2+OH+M -> HSO3+M.The ideas that gaseous H2SO4 is the end product of the reaction and that nuclei were formed from clusters of H2SO4 and H2O molecules are shown to be probably incorrect on the basis of (a) comparison to nucleation rates expected from the theory of heteromolecular homogeneous nucleation and (b) calculations indicating that nucleation rates were kinetically controlled such that the nuclei formed contained only one or two sulfur-bearing entities.The nucleation phenomena are compatible with the idea that free radicals and the hydrated complex SO3*H2O are nuclei precursors.We suggest a mechanism involving the formation and recombination of hydrated forms of HSO3 and HS)5 radicals to explain nucleation for conditions of relative humidity greater than about 5percent.For lower relative humudities the reaction SO2+O+M -> SO3+M followed by the formation of a hydrated complex of SO3 is suggested as controlling nucleation.A model based on these mechanisms yields the results that nuclei consist of single molecules of H2S2O6 or possibly H2S2O8, plus their associated H2O molecules, at high relative humuditioes (>5percent) and that at low relative humudities the nuclei consist of single molecules of H2SO4, plus associated H2O molecules.These mechanisms are used as a basis for suggesting a general explanation for the phenomenon of photoinduced nucleation.
- Friend, James P.,Barnes, Robert A.,Vasta, Rita M.
-
-
Read Online
- A novel electrode for ozone generation
-
A new type of electrode for ozone generation was fabricated by radio-frequency (RF) sputtering. High current efficiency (8%) of ozone generation is achieved at a very low current density (ca. 10 mA/cm2) with the electrode. Copyright
- Kaneda, Kazuhiro,Ikematsu, Mineo,Iseki, Masahiro,Takaoka, Daizo,Higuchi, Tohru,Hattori, Takeshi,Tsukamoto, Takeyo,Yasuda, Masashi
-
-
Read Online
- Ultraviolet absorption spectrum of chlorine peroxide, ClOOCl
-
The photolysis of chlorine peroxide (ClOOCl) is understood to be a key step in the destruction of polar stratospheric ozone. This study generated and purified ClOOCl in a novel fashion, which resulted in spectra with low impurity levels and high peak abso
- Pope, Francis D.,Hansen, Jaron C.,Bayes, Kyle D.,Friedl, Randall R.,Sander, Stanley P.
-
-
Read Online
- Water aerosol formation upon irradiation of air using KrF laser at 248nm
-
We report water aerosol formation upon irradiation of wet air with a KrF laser at 248 nm. It occurred at temperatures ranging from 0 to 50 °C and at relative humidity values from ca. 10% to 100%. Aerosols were detected either by light scattering or by dif
- Yoshihara, Keitaro,Takatori, Yoshiki,Kajii, Yoshizumi
-
-
Read Online
- Electrochemical preparation of the Ti/Ni-Sb-SnO2 for removal of phenol, in situ generated ozone
-
This present study aims to reveal the performance of Ti/Ni-Sb-SnO2 in limiting oxygen evolution and increasing electrochemical O3 production (EOP) and phenol removal. First, the effect of important variables such as current density (CD), charge
- Rahmani, Ali Reza,Nematollahi, Davood,Samadi, Mohamad Taghi,Samarghandi, Mohamad Reza,Ghasemazarian
-
p. 757 - 763
(2018/05/28)
-
- Capture of SO3 isomers in the oxidation of sulfur monoxide with molecular oxygen
-
When mixing SO with O2 in N2, Ne, or Ar, an end-on complex OS-OO forms in the gas phase and can subsequently be trapped at cryogenic temperatures (2.8-15.0 K). Upon infrared light irradiation, OS-OO converts to SO3 and SO2 + O with the concomitant formation of a rare 1,2,3-dioxathiirane 2-oxide, i.e., cyclic OS(O)O. Unexpectedly, the ring-closure of 16OS-18O18O yields a ca. 2:1 mixture of cyclic 18OS(16O)18O and 16OS(18O)18O. The characterization of OS-OO and OS(O)O with IR and UV/Vis spectroscopy is supported by high-level ab initio computations.
- Wu, Zhuang,Lu, Bo,Feng, Ruijuan,Xu, Jian,Lu, Yan,Wan, Huabin,Eckhardt, André K.,Schreiner, Peter R.,Xie, Changjian,Guo, Hua,Zeng, Xiaoqing
-
supporting information
p. 1690 - 1693
(2018/02/21)
-
- N-type TiO2 thin films for electrochemical ozone production
-
An electrode for the electrochemical production of ozone, which has the compositional sequence Si/ TiOx /Pt/ TiO2 (TiOx is titanium oxide), was fabricated by sputtering TiO2 thin film (the thickness is typically 300 nm) on a Si/ TiOx /Pt substrate. The TiO2 thin film was characterized by X-ray diffraction, transmission electron microscopy, UV photoelectron spectroscopy, UV-visible spectroscopy, and photoelectrochemical measurements: It is an n-type semiconductor of the rutile-type TiO2. The electrochemical ozone production (EOP) was realized, and a high current efficiency of 9% was achieved at a low current density of 8.9 mA cm-2 in 0.01 M HClO4 at 15°C. The observed high efficiency of EOP was considered to originate from the electrocatalysis of the n-type TiO2 in the dark when a large anodic bias was applied in which, based on the band structure of the n-type TiO 2 / HClO4 solution interface, electron tunneling can take place through a deep depletion layer of the TiO2 surface.
- Kitsuka, Kenta,Kaneda, Kazuhiro,Ikematsu, Mineo,Iseki, Masahiro,Mushiake, Katsuhiko,Ohsaka, Takeo
-
-
- Investigation of the thermal and photochemical reactions of ozone with 2,3-dimethyl-2-butene
-
The matrix isolation technique, combined with infrared spectroscopy and twin jet codeposition, has been used to characterize intermediates formed during the ozonolysis of 2,3-dimethyl-2-butene (DMB). Absorptions of early intermediates in the twin jet experiments grew up to 200% upon annealing to 35 K. A number of these absorptions have been assigned to the elusive Criegee intermediate (CI) and secondary ozonide (SOZ) of DMB, transient species not previously observed for this system. Also observed was the primary ozonide (POZ), in agreement with earlier studies. The wavelength dependence of the photodestruction of these product bands was explored with irradiation from λ ≥ 220 to ≥580 nm. Merged jet (flow reactor) experiments generated "late" stable oxidation products of DMB. A recently developed concentric jet method was also utilized to increase yields and monitor the concentration of intermediates and products formed at different times by varying the length of mixing distance (d = 0 to -11 cm) before reaching the cold cell for spectroscopic detection. Identification of intermediates formed during the ozonolysis of DMB was further supported by 18O and scrambled 16,18O isotopic labeling experiments as well as theoretical density functional calculations at the B3LYP/6-311++G(d,2p) level.
- Coleman, Bridgett E.,Ault, Bruce S.
-
p. 12667 - 12674
(2011/02/27)
-
- Electrochemical generation of ozone in a membrane electrode assembly cell with convective flow
-
Highly efficient electrochemical generation of ozone on doped tin dioxide anodes was reported recently. Here, we report the scale up of such ozone generation on a membrane electrode assembly (MEA) made with 8×13 cm -doped tin dioxide anode. The effects of
- Cui, Yuhong,Wang, Yunhai,Wang, Bin,Zhou, Haihui,Chan, Kwong-Yu,Li, Xiao-Yan
-
-
- Ex situ and in situ characterization studies of spin-coated TiO2 film electrodes for the electrochemical ozone production process
-
An electrode composed of silicon/titanium oxide/platinum/titanium dioxide (Si/TiOX/Pt/TiO2) was fabricated by spin-coating TiO2 multilayers on a Si/TiOX/Pt substrate and was used in electrochemical ozone product
- Kitsuka, Kenta,Kaneda, Kazuhiro,Ikematsu, Mineo,Iseki, Masahiro,Mushiake, Katsuhiko,Ohsaka, Takeo
-
-
- A study of sorption and decomposition of ozone on microfibrous filtering materials
-
Decomposition of ozone on commercial and pilot filtering microfibrous materials based on polymers, glass fibers, and carbonized polymeric fibers was studied.
- Klimuk,Obvintseva,Shepelev,Kuchaev,Dmitrieva,Ushakova,Avetisov
-
p. 630 - 634
(2008/09/21)
-
- Temperature dependences for the reactions of O- and O 2- with O2(a1Δg) from 200 to 700 K
-
Rate constants and product ion distributions for the O- and O2- reactions with O2(a 1Δ g) were measured as a function of temperature from 200 to 700 K. The measurements were made in a selected ion flow tube (SIFT) using a newly calibrated O2(a 1Δg) emission detection scheme with a chemical singlet oxygen generator. The rate constant for the O2- reaction is ～7 × 10-10 cm 3 s-1 at all temperatures, approaching the Langevin collision rate constant. Electron detachment was the only product observed with O2-. The O- reaction shows a positive temperature dependence in the rate constant from 200 to 700 K. The product branching ratios show that almost all of the products at 200 K are electron detachment, with an increasing contribution from the slightly endothermic charge-transfer channel up to 700 K, accounting for 75% of the products at that temperature. The increase in the overall rate constant can be attributed to this increase in the contribution the endothermic channel. The charge-transfer product channel rate constant follows the Arrhenius form, and the detachment product channel rate constant is essentially independent of temperature with a value of ～6.1 × 10-11 cm3 s-1.
- Midey, Anthony,Dotan, Itzhak,Viggiano
-
p. 3040 - 3045
(2009/02/05)
-
- Superior electrocatalysis of spin-coated titanium oxide electrodes for the electrochemical ozone production
-
A cheap spin-coated Si/TiOx/Pt/TiOx electrode is fabricated and proved to possess an excellent catalysis for ozone electrogeneration. A high current efficiency of 2.5% was obtained at 33 mA cm-2 in 10 mM HClO4 at room temperature. Copyright
- Mohammad, Ahmad M.,Kitsuka, Kenta,Kaneda, Kazuhiro,Awad, Mohamed I.,Abdullah, Aboubakr M.,Ikematsu, Mineo,Ohsaka, Takeo
-
p. 1046 - 1047
(2008/02/09)
-
- Electrochemical production of high-concentration ozone-water using freestanding perforated diamond electrodes
-
High-concentration ozone-water can be directly produced with a zero-gap electrolytic cell containing a freestanding perforated boron-doped diamond electrode. For the sake of improving current efficiency for electrochemical ozone-water production, optimization of the electrode configuration was performed. It was proven that the number of holes, hole size, and electrode thickness affect current efficiency. In particular, increasing the number of holes per unit area was the most effective method for improving current efficiency. In regard to hole size, 1 mm diameter was more appropriate than 1.5 mm diameter. Electrode thickness affected the current efficiency, and maximum values were found to be around 0.5-0.6 mm. Based on these results, an electrode optimal for electrochemical ozone-water production was prepared and achieved a maximum current efficiency of 47% in moderate conditions thus far.
- Arihara, Kazuki,Terashima, Chiaki,Fujishima, Akira
-
-
- Efficient conversion of NO2 into N2 and O2 in N2 or into N2O5 in Air by 172-nm Xe 2 excimer lamp at atmospheric pressure
-
Decomposition of NO2 (200 ppm) in N2 or air by 172-nm Xe2 excimer lamp was studied at 1 atm. The NO2 conversion in N2 was 99%, and the formation ratios of N2, O 2, NO, and N2O were 47, 98, 0, and 2%, respectively, after 30 min irradiation. The NO2 in air (5-20% O2) could be completely converted to N2O5 and HNO3 due to reactions by O3 and H2O after only 1.0-1.5 min irradiation. The present results give a new simple photochemical aftertreatment technique of NO2 in air without using any catalysts. Copyright
- Tsuji, Masaharu,Kawahara, Masashi,Senda, Makoto,Noda, Kenji
-
p. 376 - 377
(2007/10/03)
-
- Many-electron oxidation of water as treated within the framework of a functional chemical model of the manganese cofactor of oxidase in photosystem II of natural photosynthesis
-
The kinetics and products of the oxidation of water by MnIV clusters in a 12 M sulfuric acid solution, a functional chemical model of the manganese cofactor of the oxidase in photosystem II of natural photosynthesis, were studied. It was demonstrated that, depending of the conditions, water can be oxidized to either oxygen or ozone. In the reaction mixture, ozone is rapidly and almost completely converted into oxygen. The results obtained were compared to the data on the photosynthetic oxidation of water in red seaweeds. Nauka/Interperiodica 2007.
- Dzhabiev,Moiseev
-
p. 284 - 290
(2007/10/03)
-
- Temperature dependence of the HO2 + ClO reaction. 2. Reaction kinetics using the discharge-flow resonance-fluorescence technique
-
The total rate coefficient, k3, for the reaction HO2 + ClO→ products has been determined over the temperature range of 220-336 K at a total pressure of approximately 1.5 Torr of helium using the discharge-flow resonance-fluorescence technique. Pseudo-first-order conditions were used with both ClO and HO2 as excess reagents using four different combinations of precursor molecules. HO2 molecules were formed by using either the termolecular association of H atoms in an excess of O2 or via the reaction of F atoms with an excess of H 2O2. ClO molecules were formed by using the reaction of Cl atoms with an excess of O3 or via the reaction of Cl atoms with Cl2O. Neither HO2 nor ClO were directly observed during the course of the experiments, but these species were converted to OH or Cl radicals, respectively, via reaction with NO prior to their observation. OH fluorescence was observed at 308 nm, whereas Cl fluorescence was observed at approximately 138 nm. Numerical simulations show that under the experimental conditions used secondary reactions did not interfere with the measurements; however, some HO2 was lost on conversion to OH for experiments in excess HO2. These results were corrected to compensate for the simulated loss. At 296 K, the rate coefficient was determined to be (6.4 ±1.6) x 10-12 cm3 molecule-1 s _1. The temperature dependence expressed in Arrhenius form is (1.75 ±0.52) x 10-12 exp[(368 ±78)/T] cm3 molecule-1 s_1. The Arrhenius expression is derived from a fit weighted by the reciprocal of the measurement errors of the individual data points. The uncertainties are cited at the level of two standard deviations and contain contributions from statistical errors from the data analysis in addition to estimates of the systematic experimental errors and possible errors from the applied model correction.
- Hickson, Kevin M.,Keyser, Leon F.,Sander, Stanley P.
-
p. 8126 - 8138
(2008/10/09)
-
- Ozone synthesis under UV irradiation
-
The main parameters governing the ozone concentration and the yield of an ozone generator were studied: the power and frequency of the voltage applied to UV lamp, temperature, and humidity of air. The relationship between these parameters and the ozone concentration was established. Nauka/Interperiodica 2006.
- Nakashidze,Mgaloblishvili,Dadunashvili,Mgaloblishvili,Turkadze
-
p. 1344 - 1346
(2007/10/03)
-
- Oxidation of carbon monoxide on group 11 metal atoms: Matrix-isolation infrared spectroscopic and density functional theory study
-
Laser-ablated Cu, Ag, and Au atoms react with CO and O2 mixture in solid argon to produce carbonyl metal oxides, (O2)Cu(CO) n (n = 1, 2), (η1-OO)MCO (M = Ag, Au), OCAuO 2CO, and OAuCO, as well as grou
- Xu, Qiang,Jiang, Ling
-
p. 2655 - 2662
(2008/10/09)
-
- Electrolytic generation of ozone on antimony- And nickel-doped tin oxide electrode
-
In a recent report, ozone was produced with high efficiency in perchloric acid on an anode coated with antimony-doped tin oxide. We report here that high current efficiency can be enhanced if trace amounts of a second dopant, nickel, is present. The effect of composition of the coating in terms of Ni:Sb:Sn was carefully analyzed. The optimum Ni:Sb:Sn ratio, determined to be 1:8:500, was determined giving a corresponding ozone generation current efficiency of over 30% at room temperature. The highest current efficiency was observed at an optimum operating potential of 2.2 V vs Ag/AgCl. Electrolytic generation of ozone in perchloric acid, sulfuric acid, and phosphoric acid at different concentrations was also studied and compared. In 0.1 M H2SO 4, the ozone concentration reached 34 mg/L and a current efficiency of 36.3% could be achieved. This is about the highest current efficiency ever reported for electrolytic generation of ozone in an aqueous medium at room temperature.
- Wang, Yun-Hai,Cheng, Shaoan,Chan, Kwong-Yu,Li, Xiao Yan
-
p. D197-D200
(2008/10/09)
-
- Formation of ozone during the reduction of potassium permanganate in sulfuric acid solutions
-
The kinetics and mechanism of the reduction of KMnO4 in sulfuric acid solutions were studied. It was demonstrated that the Mn(VII)-containing compounds formed from KMnO4 in 18 M sulfuric acid decompose unimolecularly to yield molecul
- Dzhabiev,Denisov,Moiseev,Shilov
-
p. 1755 - 1760
(2007/10/03)
-
- A high-resolution FT-IR study of the fundamental bands v7, v8, and v18 of ethene secondary ozonide
-
Ozonization reaction of ethene in neat film at 77 K was performed. Separation of ethene secondary ozonide from the other products of the reaction was performed by continuous pumping of the reactor. Only the products, which evaporated from the walls of the reactor at 185 K, were transferred to the gas cell. The high-resolution infrared absorption spectrum of gaseous ethene secondary ozonide (C2H4O3) in a static gas long-path absorption cell has been recorded in the 900-1100 cm-1 spectral region at 185 K. The spectral resolution was 0.003 cm-1. Analyses of the v7(A) band at 1037.0 cm-1, the v 8(A) band at 956.1 cm-1, and the V18(B) band at 1082.1 cm-1 have been performed using the Watson Hamiltonian model (A, reduction; IIIr, representation). A set of ground-state rotational and quartic centrifugal distortion constants have been obtained, and upper state spectroscopic constants have been determined for the bands investigated. A local resonance observed in v18 is explained as c-Coriolis interaction with v10+ v11.
- Sablinskas, Valdas,Hegelund, Flemming,Ceponkus, Justinas,Bariseviciute, Ruta,Aleksa, Valdemaras,Nelander, Bengt
-
p. 8719 - 8723
(2008/10/09)
-
- Measurement of the rate coefficient for collisional removal of O 2 (X3∑g-, ν=1) by O( 3P)
-
We report a laboratory measurement of the rate coefficient for the collisional removal of O2 (X Σg-3, ν=1) by O (P3) atoms. In the experiments, 266-nm laser light photodissociates ozone in a mixture of molecular oxygen and ozone. The photolysis step produces vibrationally excited O2 (a Δg1) that is rapidly converted to O2 (X Σg-3, ν=1-3) in a near-resonant electronic energy-transfer process with ground-state O2. In parallel, a large amount of O (D1) atoms is generated that promptly relaxes to O (P3). Under the conditions of the experiments, only collisions with the photolytically produced O (P3) atoms control the lifetime of O2 (X Σg-3, ν=1), because its removal by molecular oxygen at room temperature is extremely slow. Tunable 193-nm laser light monitors the temporal evolution of the O2 (X Σg-3, ν=1) population by detection of laser-induced fluorescence near 360 nm. The removal rate coefficient for O2 (X Σg-3, ν=1) by O (P3) atoms is (3.2±1.0) × 10-12 cm3 s-1 (2δ) at a temperature of 315±15 K (2δ). This result is essential for the analysis and correct interpretation of the 6.3-μm H2 O (ν2) band emission in the Earth's mesosphere and indicates that the deactivation of O2 (X Σg-3, ν=1) by O (P3) atoms is significantly faster than the nominal values recently used in atmospheric models.
- Kalogerakis, Konstantinos S.,Copeland, Richard A.,Slanger, Tom G.
-
-
- Core excitation in O3 localized to one of two symmetry-equivalent chemical bonds: Molecular alignment through vibronic coupling
-
Core excitation from terminal oxygen OT in O3 is shown to be an excitation from a localized core orbital to a localized valence orbital. The valence orbital is localized to one of the two equivalent chemical bonds. We experimentally demonstrate this with the Auger-Doppler effect which is observable when O3 is core excited to the highly dissociative OT 1 s-1 7 a11 state. Auger electrons emitted from the atomic oxygen fragment carry information about the molecular orientation relative to the electromagnetic-field vector at the moment of excitation. The data together with analytical functions for the electron-peak profiles give clear evidence that the preferred molecular orientation for excitation only depends on the orientation of one bond, not on the total molecular orientation. The localization of the valence orbital " 7 a1 " is caused by mixing of the valence orbital " 5 b2 " through vibronic coupling of antisymmetric stretching mode with b2 symmetry. To the best of our knowledge, it is the first discussion of the localization of a core excitation of O3. This result explains the success of the widely used assumption of localized core excitation in adsorbates and large molecules.
- Wiesner,Naves De Brito,Sorensen,Kosugi,Bjoerneholm
-
-
- Laboratory intercomparison of the ozone absorption coefficients in the mid-infrared (10 μm) and ultraviolet (300-350 nm) spectral regions
-
For the measurement of atmospheric ozone concentrations, the mid-infrared and ultraviolet regions are both used by ground-, air-, or satellite-borne instruments. In this study we report the first laboratory intercomparison of the ozone absorption coefficients using simultaneous measurements in these spectral regions. The intercomparison shows good agreement (around 98.5%) between the HITRAN 2000 recommendation for the mid-infrared and the most reference measurements in the ultraviolet regions, whereas systematic differences of about 5.5% are observed when using the recommendation of HITRAN2003 for the mid-infrared. Possible reasons for this discrepancy are discussed. Future measurements are clearly needed to resolve this issue.
- Picquet-Varrault,Orphal,Doussin,Carlier,Flaud
-
p. 1008 - 1014
(2007/10/03)
-
- Measurements of the Rate Constant of HO2 + NO2 + N2 → HO2NO2 + N2 Using Near-Infrared Wavelength-Modulation Spectroscopy and UV-Visible Absorption Spectroscopy
-
The reaction HO2 + NO2 → HO2NO2 + N2 (reaction 1) was reexamined using UV spectroscopy to monitor NO2, and near-IR wavelength-modulation spectroscopy to monitor HO2. The use of the near-IR heterodyne technique for HO2 detection had several advantages over UV detection including improved sensitivity (by at least an order of magnitude) and freedom from spectral interferences since HO2 was probed via a single rovibronic transition. Methanol, which was used as a precursor for HO2, enhanced the reaction rate through a chaperone mechanism involving a HO2·CH3OH complex. The enhancement of reaction 1 by methanol was studied and found to be very similar to that for the methanol enhancement at the HO2 self-reaction. An unexpected time-dependent UV absorption unaccounted for in previous examinations of reaction 1 that employed UV spectroscopy to monitor HO2 was observed. This absorption, which may have led to errors in those prior studies, was due to the process NO2 + NO2 ? N2O4.
- Christensen, Lance E.,Okumura, Mitchio,Sander, Stanley P.,Friedl, Randall R.,Miller, Charles E.,Sloan, James J.
-
-
- Catalytic oxidation of benzene with ozone over alumina-supported manganese oxides
-
Catalytic oxidation of benzene with ozone over alumina-supported manganese oxides was carried out at room temperature (295 K) to investigate the behavior of benzene oxidation and COx formation. The ratio of the decomposition rate for ozone to that for benzene was found to be 6, independent of ozone concentration, reaction times, and the amount of Mn loading. A linear correlation was observed for the amount of ozone decomposed and that of COx formed, whereas deviation from linearity was observed between the amount of ozone decomposed and that of benzene reacted. Carbon balance was in the range of 26-37% due to the formation of two types of intermediates, weakly bound compounds including formic acid and strongly bound surface formate and carboxylates. Catalyst was significantly deactivated due to the buildup of the intermediates on the catalyst surface during the course of benzene oxidation. The weakly bound compounds were removed by heat treatment at 573 K in the O2 flow. The strongly bound surface formate and carboxylates were oxidized to COx by further heating up to 723 K. The deactivated catalyst was regenerated by the heat treatment.
- Einaga, Hisahiro,Futamura, Shigeru
-
p. 304 - 312
(2008/10/09)
-
- Interaction of gas-phase ozone at 296 K with unsaturated self-assembled monolayers: A new look at an old system
-
The oxidation of organics adsorbed on surfaces by ozone is of fundamental chemical interest and potentially important in the lower atmosphere. Studies of the oxidation of the three-carbon and eight-carbon vinylterminated self-assembled monolayers (SAMs, C3= and C8=) on a silicon ATR (attenuated total reflectance) crystal by gas-phase O3 at 296 K are reported. Oxidation of the SAMs was followed in real time by ATRFTIR using ozone concentrations that spanned 5 orders of magnitude, from ～1011 to 1016 molecules cm-3. For comparison, some studies of the saturated C8 SAM were also carried out. The films were also characterized by atomic force microscopy and water contact angle measurements. The loss of C=C and the formation of C=O were measured in real time and shown to be consistent with a Langmuir-Hinshelwood mechanism in which O3 is rapidly adsorbed on the surface and then reacts more slowly with the alkene moiety. This is supported by molecular dynamics (MD) calculations which show that O3 does not simply undergo elastic collisions but has a significant residence time on the surface. However, the kinetics measurements indicate a much longer residence time than the MD calculations, suggesting a chemisorption of O 3. Formaldehyde was observed as a gas-phase product by infrared cavity ring down spectroscopy. Possible mechanisms of the ozonolysis and its atmospheric implications are discussed.
- Dubowski, Yael,Vieceli, John,Tobias, Douglas J.,Gomez, Anthony,Lin, Ao,Nizkorodov, Sergey A.,McIntire, Theresa M.,Finlayson-Pitts, Barbara J.
-
p. 10473 - 10485
(2008/01/27)
-
- Experimental evidence for acceleration of reaction between iodine monoxide and chlorine monoxide at the reactor surface
-
The reaction of iodine monoxide with chlorine monoxide resulting in atom escape to the gas phase is studied at T = (303 ± 5) K and P = 2.5 Torr using a flow setup for measuring the resonance fluorescence signals of atomic iodine and chlorine. The heterogeneous reaction between chlorine monoxide and iodine monoxide occurring at the reactor surface covered with an F32-L Teflon-like compound and treated by the reaction products is characterized by the rate constant k = (4.9 ± 0.2) x 10-11 cm3 molecule-1 s-1. This value is substantially higher than the rate constant for the homogeneous reaction IO. + ClO. (k1 ≤ 1 x 10-12 cm3 molecule-1 s-1).
- Larin,Spasskii,Trofimova,Turkin
-
p. 202 - 210
(2008/10/08)
-
- Temperature and pressure dependence study of the reaction of IO radicals with dimethyl sulfide by cavity ring-down laser spectroscopy
-
The reaction of IO radicals with dimethyl sulfide was studied using cavity ring-down laser spectroscopy. The reaction rate constant shows both a temperature and pressure dependence. At 100 Torr total pressure, the reaction has reached its high-pressure limit and has a rate constant of (2.5 ± 0.2) × 10-13 molecule-1 cm3 s -1 at 298 K. On the basis of the Arrhenius plot in the region of 273-312 K, the reaction has a negative activation energy (Ea = -18.5 ± 3.8 kJ mol-1). The atmospheric implications of these findings are discussed. In light of these new data, DMS oxidation by IO can compete with oxidation by the hydroxyl radical in the marine boundary layer. Quoted uncertainties are one standard deviation from regression analysis.
- Nakano, Yukio,Enami, Shinichi,Nakamichi, Shinji,Aloisio, Simone,Hashimoto, Satoshi,Kawasaki, Masahiro
-
p. 6381 - 6387
(2007/10/03)
-
- Development of a Photoresist Removal Method Using Ozone Gas with Water Vapor for LCD Manufacturing
-
A photoresist removal method for liquid crystal display manufacturing, using highly concentrated ozone gas and water vapor, has been developed. This method overcomes limitations of conventional ozone processing for resist removal, and obtains a resist removal rate over 1 μm/min at substrate temperatures lower than 100°C. In our experiment, ozone gas was bubbled into water, and water vapor concentration in the gas phase was controlled by the water temperature (Tw). The influence of treatment parameters, such as substrate temperature (Ts), water vapor concentration, and residence time (τ), on the removal rate has been experimentally examined. The treatments were performed at Ts = 25-83°C, Tw = 27-92.5°C, τ = 0.5-2 min, ozone concentration [O3] 0 = 4.2-10.7 vol % (90-230 g/m3), gas flow rate 1-12.5 slm, and total pressure 100 kPa. The observed removal rate was 1.4 μm/min for a sample with a dry etching treatment at Ts = 83°C, T w = 90°C, and [O3] = 10.7 vol %. It was also shown that the difference between the water and the substrate temperatures, T w - Ts, was a critical parameter for determining the removal rate. The removal rate in this process is more than ten times greater than that of the conventional ozone processing, such as ozone gas ashing and ozonized water treatment. A higher removal rate was realized by optimizing the amount of condensed water with respect to a resist oxidation rate and the diffusion rate of ozone into the resist in the water.
- Noda, Seiji,Miyamoto, Makoto,Horibe, Hideo,Oya, Izumi,Kuzumoto, Masaki,Kataoka, Tatsuo
-
p. G537-G542
(2008/10/08)
-
- Investigation of the reaction of O3+ with N2 and O2 from 100 to 298 K
-
The kinetics of the reaction of O3+ with N2 and O2 have been studied at 100 and 298 K in a variable temperature-selected ion flow tube (VT-SIFT). The rate constants for O3+ reacting with N2 measured in the VT-SIFT are slow, proceeding at -13 cm3 s-1 at both temperatures, in disaggrement with recent measurements by Cacace et al.1 of the total rate constant of ca. 1.7 × 10-10 cm3 s-1 at 298 K. However, a N2O3+ intermediate postulated to be involved in the reaction has been observed at 100 K, in agreement with the previous experimental and theoretical results. Rate constants for the reaction of O3+ with O2 at 100 and 298 K have also been measured in the VT-SIFT. The O2 reaction rate constants are 3.1 × 10-10 and 2.9 × 10-10 cm3 s-1 at 100 and 298 K, respectively, which are ca. half of the Langevin collision rate constant. Discrepancies between the current results and those of Cacace et al. in regard to the rate constants measured and the N2O+ product ions observed are discussed in light of newer data for the O3+ chemistry and the contributions of excited-state species.
- Midey, Anthony J.,Williams, Skip,Miller, Thomas M.,Larsen, Patrick T.,Viggiano
-
p. 11739 - 11742
(2007/10/03)
-
- Matrix infrared spectroscopic studies of the photo-dissociation at 266 nm of C1NO2 and of C1ONO
-
Detailed infrared spectroscopic studies of the photo-dissociation at 266 nm of C1NO2 trapped in argon matrices with subsequent experiments conducted with a xenon lamp at λ > 360 nm are reported. Formation of cis and trans C1ONO in equilibrium with C1NO2 is observed after irradiation at 266 nm. λ > 360 nm the transformation of trans C1ONO into cis C1ONO occurs. On prolonged photolysis at 266 nm, C1ONO dissociates into C1ON and O(1D) atom and into C10 + NO as evidenced in reactive matrices (solid oxygen and nitrogen).
- Coanga,Schriver-Mazzuoli,Schriver,Dahoo
-
p. 309 - 320
(2008/10/08)
-
- Reactive uptake of ozone by oleic acid aerosol particles: Application of single-particle mass spectrometry to heterogeneous reaction kinetics
-
The technique of single-particle mass spectrometry has been coupled to a reaction flow tube to measure the uptake coefficient, γ, of ozone (O3) by oleic acid (9-octadecenoic acid) aerosol particles. The reaction was followed by monitoring the decrease of oleic acid in the size-selected particles as a function of O3 exposure. The reactive uptake coefficient is found to depend on the size of the particle, with γmeas ranging from (7.3 ± 1.5) × 10-3 to (0.99 ± 0.09) × 10-3 for particles ranging in radius from 680 nm to 2.45 μm. It is suggested that the decrease in γmeas with increasing particle size results from the reaction being limited by the diffusion of oleic acid within the particle, and based on our measurements we estimate the value of γ to be (5.8-9.8) × 10-3 for particles that are not limited by oleic acid diffusion. A reaction model that includes simultaneous diffusion and reaction of both O3 and oleic acid is developed and used to fit the observed rates of reaction. Solutions obtained from this model indicate that oleic acid must diffuse within the particle more slowly than is predicted by the measured oleic acid self-diffusion constant.1 It is proposed that this oleic acid-diffusion-limited uptake is attributable to the ozonolysis reaction products. Furthermore, these experiments demonstrate that it is not always possible to describe heterogeneous uptake by a model that decouples all relevant processes, including reaction and diffusion. Finally, the possible implications that these findings have for the role of particle morphology in the reaction of gas-phase species with atmospheric aerosols are discussed.
- Smith, Geoffrey D.,Woods III, Ephraim,DeForest, Cindy L.,Baer, Tomas,Miller, Roger E.
-
p. 8085 - 8095
(2007/10/03)
-
- Reactions in air and nitrogen in the plasma of a corona discharge between the surface of water and an electrode
-
Chemical reactions that occur in air and nitrogen under the action of a flare corona discharge between the surface of distilled water and a solid electrode were studied. The major products formed under these conditions were ozone, NO-3, and ammonium ions. Their yields in the air were 130, 5.6, and 0.068 mol/mol electrons (molecules per one electron passed through the circuit), respectively. In nitrogen, ammonium ions were only formed in the same yield. A kinetic model of the reactions was suggested. The model correctly described the experimental data on changes in the acidity of water and accumulation of ammonium ions. The model was checked by calculating and measuring the oxidation of I- in a solution of KI (0.01 mol/1) and the oxidation of Fe2+ in a solution of Mohr's salt (0.025 mol/1). The results verified correctness of the model.
- Piskarev
-
p. 1832 - 1836
(2007/10/03)
-
- Infrared spectra of cis- and trans-peroxynitrite anion, oono-, in solid argon
-
The peroxynitrite anion, of vast importance in biochemistry, is formed in vivo from the reaction of NO and O2-. Laser ablation of 10 different metal targets with concurrent 7 K codeposition of NO/Ar and O2/Ar mixtures give
- Liang,Andrews
-
p. 9848 - 9854
(2007/10/03)
-
- KrF excimer laser-induced ozone formation in supercritical carbon dioxide
-
Laser-induced reactions by a pulsed KrF excimer laser were studied using UV absorption spectroscopy in sub- and supercritical O2/CO2 mixtures up to the pressure of 15 MPa (corresponding density, 17 mol dm-3). Although the 248 nm excimer laser photon energy is smaller than the energy required for dissociating O2, ozone formation was observed in O2/CO2 mixtures. Under the laser irradiation, O3 concentration increased monotonically with the increase of the irradiation time and then stayed constant, which is satisfactorily expressed by the equation d[O3]/dt = a-b[O3]. a corresponds to O3 formation rate and b to O3 decomposition rate constant. The value of a increased with the increase of CO2 density up to 3 mol dm-3 and was then kept almost constant with further increase. O2 absorbs a photon to yield an oxygen molecule in the Herzberg III state O2(A′ 3Δu), being augmented along with the increase of CO2 density. In pure O2, the predominant pathway of O3 formation is the reaction between excited O2 in Herzberg states and ground state O2 to yield O3 and atomic oxygen. In high-density O2/CO2 mixtures, O3 is considered to be produced through reaction between the Herzberg states O2 and CO2. Taking account of the quenching effect for the above reaction together with the augmentation of O2 absorption of laser light by the high-density CO2, the behavior of a with respect to CO2 density was satisfactorily explained. The behavior of b suggested a certain inhibition of O3 recovery in high-density CO2 after the photodecomposition of the product O3, which was ascribed to the formation of CO3 from the O(1D) reaction with CO2. A certain cage effect for the O3 photodecomposition was also suggested. No specific pressure effect was observed near the critical point.
- Otomo, Junichiro,Oshima, Yoshito,Takami, Akinori,Koda, Seiichiro
-
p. 3332 - 3340
(2007/10/03)
-
