H2O O2 Research Articles

Collision-Induced Absorption in the a1Δg(v′=0)←X3Σg−(v=0) Transition in O2–CO2, O2–N2, and O2–H2O Mixtures

When O2 is perturbed by collisions with other molecules, the weak spin-forbidden magnetic dipole transition a1Δg←X3Σg− shows a broad continuum absorption underlying the sharp lines. This collision-induced enhancement absorption plays a role in the Earth's atmosphere and much experimental work has been carried out to measure the binary absorption coefficient with different perturber gases. Recent work on the v′=0←v=0 band in O2–CO2 mixtures yielded a value for the coefficient that was approximately three times that of earlier measurements on O2–N2 mixtures. In the present note, we calculate the absorption theoretically assuming that the long-range quadrupole-induced dipole mechanism is dominant. Using experimental polarizability matrix elements of CO2 and ab initio results in the literature for the quadrupolar transition matrix element for O2, we find good agreement for O2–CO2 mixtures without any adjustable parameters. The agreement for O2–N2 is less good, and because of the much smaller polarizability of N2 than of CO2, we suggest that one has to include a short-range component in addition to the long-range one treated here. We also calculate the binary absorption coefficient for O2–H2O, for which no experimental data are available, and we synthesize the corresponding spectrum for use in atmospheric modeling.

Effect of Water Vapor on the Oxidation Behavior of Fe–1.5Si in Air at 1073 and 1273 K

The oxidation behavior of Fe–1.5Si was investigated at 1073 and 1273 K in air, air–H2O, Ar–H2O, O2–H2O, and O2 atmospheres. The extent of corrosion in atmospheres containing H2O increased rapidly after an incubation period of slow oxidation, the incubation period becoming shorter in the order, O2–H2O, air–H2O, and Ar–H2O. With increasing H2O contents in air–H2O, the incubation time decreased. During the incubation period, oxidation was slow, because of the formation of an inner Si-rich oxide layer and a Pt marker was located between the external Fe2O3 (Fe3O4 included) and an inner Si-rich oxide layer. During the rapid oxidation, the inner FeO+Fe2SiO4 layer thickened and a Pt maker was at the interface between an external Fe-oxide and an inner FeO+Fe2SiO4 layer. Observations of scale cross sections indicated that voids made channels along the boundaries of columnar FeO crystals, suggesting transport of water molecules. The Si-rich oxide layer changed into an FeO+Fe2SiO4 mixture due to penetration of water molecules. A combined process of perforating dissociation and transport of water molecules is suggested to be the cause of the rapid growth of the inner FeO+Fe2SiO4 layer.

Effect of synthesis conditions on the size and aspect ratio of acicular iron(III) α-oxyhydroxide particles prepared in the FeSO4-NH4OH-O2-H2O system

The conditions for the synthesis of iron(III) α-oxyhydroxide in the FeSO4–NH4OH–O2–H2O system were optimized (pH 7): [FeSO4] = 0.7–1 mol/l, [NH4OH] = 3 mol/l, reaction temperature between 42 and 55°C, and oxygen flow rate in the range 7–50 l/h. Increasing the solution pH leads to the formation of iron(III) α-oxyhydroxide particles with an increased aspect ratio. In the best samples of iron(III) α-oxyhydroxide obtained, the particle size is 0.25–0.30 μm, and the aspect ratio is 10–15.

Nitrogen species in the post‐Pinatubo stratosphere: Model analysis utilizing UARS measurements

We present an analysis of the impact of heterogeneous chemistry on the partitioning of nitrogen species measured by the Upper Atmosphere Research Satellite (UARS) instruments. The UARS measurements utilized include N2O, HNO3, and ClONO2 from the cryogenic limb array etalon spectrometer (CLAES), version 7 (v.7), and temperature, methane, ozone, H2O, HCl, NO and NO2 from the halogen occultation experiment (HALOE), version 18. The analysis is carried out for the UARS data obtained between January 1992 and September 1994 in the 100‐ to 1‐mbar (∼17–47 km) altitude range and over 10° latitude bins from 70°S to 70°N. The spatiotemporal evolution of aerosol surface area density (SAD) is adopted from analysis of the Stratospheric Aerosol and Gas Experiment (SAGE) II data. A diurnal steady state photochemical box model, constrained by the temperature, ozone, H2O, CH4, aerosol SAD, and columns of O2 and O3 above the point of interest, has been used as the main tool to analyze these data. Total inorganic nitrogen (NOy) is obtained by three different methods: (1) as a sum of the UARS‐measured NO, NO2, HNO3, and ClONO2; (2) from the N2O‐NOy correlation, and (3) from the CH4‐NOy correlation. To validate our current understanding of stratospheric heterogeneous chemistry for post‐Pinatubo conditions, the model‐calculated monthly averaged NOx/NOy ratios and the NO, NO2, and HNO3 profiles are compared with the UARS‐derived data. In general, the UARS‐constrained box model captures the main features of nitrogen species partitioning in the post‐Pinatubo years, such as recovery of NOx after the eruption, their seasonal variability and vertical profiles. However, the model underestimates the NO2 content, particularly in the 30‐ to 7‐mbar (∼23–32 km) range. Comparisons of the calculated temporal behavior of the partial columns of NO2 and HNO3 and ground‐based measurements at 45°S and 45°N are also presented. Our analysis indicates that ground‐based and HALOE v. 18 measurements of the NO2 vertical columns are consistent within the range of their uncertainties and are systematically higher (up to 50%) than the model results at midlatitudes in both hemispheres. Reasonable agreement is obtained for HNO3 columns at 45°S, suggesting some problems with nitrogen species partitioning in the model. Outstanding uncertainties are discussed.

Computer simulation of water clusters containing an H2O–O2 charge-transfer complex

A proposed mechanism for the photonucleation of water vapour in the presence of oxygen involves the initial formation of a charge-transfer (CT) complex of molecular oxygen and water, H 2 O + O 2 - . The large dipole of this complex then attracts the surrounding polar water molecules, thereby forming a cluster. To investigate the properties of such a cluster, we have carried out computer simulations at 300 K using two different water models. For both models, we found that the complex resided preferentially at the surface of the cluster despite its large dipole moment. This preference was in accord with the results of ab initio calculations carried out on a small cluster. The internal energy difference between a cluster of n water molecules and a cluster of (n-1) water molecules and one complex was of the order of 10–20 kJ mol -1 , the precise value depending on the cluster size. This energetic stabilisation reflects the fact that the CT complex can make three hydrogen bonds in contrast to the two made by a water molecule.

Effects of H2O on the particle size in the vapor-phase synthesis of TiO2

Vapor-phase synthesis of ultrafine TiO2 particles was investigated experimentally in the simultaneous hydrolysis and oxidation of TiCl4. Experiments were made for the control of particle size, size distribution and phase composition of ultrafine TiO2 particles with the preheating of reactants. The molar ratio of H2O/TiCl4 was adopted as a variable for the control of particle size and size distribution in various reaction systems such as TiCl4–H2O, TiCl4–H2O–O2, and TiCl4–H2O–air. As the molar ratio of H2O/TiCl4 increased from 2 to 12, the average particle size decreased from 45 nm to 19 nm, and the rutile content of TiO2 powders increased from 21% to 54% in the TiCl4–H2O system. Changes in the average particle size were the same in the TiCl4–H2O–O2 system as in the TiCl4–H2O system, but particle-size distributions were narrower in the TiCl4–H2O–O2 system. The same tendencies of average particle size, size distribution and rutile content were also found in the TiCl4–H2O–air system. A high production rate of ultrafine TiO2 particles was obtained at the condition of high mole fraction of TiCl4 and low gas-flow rate in the presence of water vapor and preheating of reactants.

Fitting and scaling laws for high temperature Q branch collapse in the O2 stimulated Raman spectra in O2–H2O mixtures

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Temperature Dependence of Oxygen Diffusion in H2O and D2O

The diffusion coefficient of O2 in H2O and D2O has been determined as a function of temperature from −0.5 to 95 °C, using the Taylor dispersion technique with optical absorbance detection at 200 nm. Over this temperature range, significant deviation from both Arrhenius and Stokes−Einstein behavior is found. A practical interpolation formula for the H2O solvent is (T in Kelvin) log10[D/cm2 s-1] = −4.410 + 773.8/T − (506.4/T)2 and, for the D2O solvent, log10[D/cm2 s-1] = −4.706 + 903.6/T − (526.6/T)2. As a test of the apparatus, the diffusion coefficient of nitrobenzene in water was carefully measured and found to be 1.04 × 10-5 cm2 s-1 at 26 °C and 2.14 × 10-5 cm2 s-1 at 60.1 °C.

Electrical and structural properties of indium tin oxide films deposited by reactive DC sputtering

High-quality indium tin oxide (ITO) films were deposited by reactive DC sputtering on glass and quartz substrates. Both pure H2O vapour and O2 were used as reactive sputtering atmospheres. The electrical parameters, free carrier concentration and carrier mobility as well as the resistivity of the ITO films were optically and contactlessly determined from IR reflection spectra by applying the Drude theory. Electrical properties of ITO films were examined as a function of deposition parameters, layer thickness and annealing procedures. The DC-H2O-sputtered ITO films show improved electrical properties because of a high free carrier concentration of N=6.2*1020 cm-3 immediately after deposition compared with a maximum of N=4*1020 cm-3 for DC-O2-sputtered ITO films occurring only after thermal annealing. Moreover, another annealing characteristic of DC-H2O-sputtered ITO films was detected because of their increasing resistivity during N2 annealing in contrast to DC-O2-sputtered ITO films. The low resistivity of ITO films, deposited by application of H2O as a reactive sputtering atmosphere, is due to an improvement in crystallinity and an increase in the donor level of Sn and O vacancies.

Adhesion properties of a structural etch stop material for use in multilayer electronic wiring structures

A thermally stable copolymer of a polyimide and a dianiline terminated polydimethylsiloxane has been developed for use as a structural oxygen etch barrier material in high performance multilayer electronic wiring structures. We report on the preparation of the etch barrier material and on investigations of the etch stop and adhesion properties of this material. Studies on the effects of adhesion-promoting plasma treatments are supported by x-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS) data. Before plasma treatment, it is observed that the siloxane component segregates to the surface. After either an O2 reactive ion etch treatment or H2O plasma exposure, the unusual XPS charging effects are interpreted as a surface layer containing two distinct phases: the etched polyimide fraction and a partial overlayer of a carbon containing SiO2

The role of water in promoting the oxidative dehydrogenation of ethane

AbstractThe addition of water vapor has a strong positive effect on the rate of ethane oxidation at 575°C. This effect is attributed to the role of H2O as a third body in the decomposition of H2O2 to OH radicals. Carbon tetrafluoride likewise enhances the rate of ethane conversion, although not to the extent realized with H2O. A kinetic model, based on known elementary reactions, adequately accounts for the conversions and selectivities observed as a function of H2O pressure, temperature, contact time, and O2 pressure. © 1994 John Wiley & Sons, Inc.

Diode-laser absorption technique for simultaneous measurements of multiple gasdynamic parameters in high-speed flows containing water vapor

A distributed-feedback InGaAsP diode laser, emitting near 1.38 µm, was used to acquire spectrally resolved absorption profiles of H(2)O lines in the ν(1) + ν(3) band at a repetition rate of 10 kHz. The profiles were used for simultaneous measurements of flow parameters in high-speed, one-dimensional (1-D) transient flows generated in a shock tube. Velocity was determined from the Doppler shift, which was measured with a pair of profiles simultaneously acquired at different angles with respect to the flow direction. Temperature was determined from the intensity ratio of two adjacent lines. Pressure and density were found from the fractional absorption. From these primary gasdynamic variables, the mass and momentum fluxes were determined. Experiments were conducted with three different gas mixtures in the shock tube: pure H(2)O at initial pressures lower than 3 Torr, up to 6% of H(2)O in O(2) at initial pressures below 120 Torr, and up to 8% of H(2)O in O(2) at initial pressures below 35 Torr. In the third case, pyrolysis of H(2) /O(2) behind incident shocks produced known yields of H(2)O. With all three mixtures, results compare well with 1-D shock calculations. This H(2)O diagnostic strategy shows promise for applications in both ground and flight testing.

Increased oxygen species generation in blood monocytes of asthmatic patients.

Besides eosinophils, inflammatory processes in asthma are characterized by an infiltration of inflammatory cells, including mononuclear phagocytes, such as alveolar macrophages (AM) and blood monocytes, in the airways. Monocyte activation has been observed in the blood after exercise or allergen-induced asthma. Stimulated AM in chronic and stable asthmatic patients have been shown to release oxygen species. We thus investigated the intensity of the activation of monocytes from 18 asthmatic patients compared with 18 healthy subjects. Oxygen species release was analyzed for monocytes in suspension by chemiluminescence using a luminometer and for monocytes maintained in adherence using conventional assay and video imaging camera. Circulating blood monocytes in suspension from asthmatic patients and control subjects showed the same baseline free radical release. Monocytes in suspension from asthmatic patients were more stimulatable by PMA: specifically, monocytes release more H2O and peaks of O2-. are sooner; moreover, peaks of total free radical release are higher, and this plateau is sustained. Compared with monocytes from control subjects, those from asthmatic patients evaluated after adherence show a higher baseline for O2-. and higher total free radical release. Monocytes from asthmatic patients spontaneously release more O2-. over time in nonstimulated cells and release more O2-. with PMA stimulation; they show the same peak level total free radical release as those from control subjects after stimulation. SOD activity analysis on adherent monocytes was lower in asthmatic compared with control subjects. These data show that monocytes from asthmatic patients were activated compared with control monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

２八面体型スメクタイトの加熱処理による構造変化

Structural rearrangements for dioctahedral smectite after thermal treatment were investigated. The notable structural changes accompanying removal of interlayer water are contraction of basal spacing, migration of interlayer cation into silicate layer and expansion of b-parameter. The important factor affecting the migration of interlayer cation is considered to be turbostatic stacking of adjacent silicate layers. The dehydroxylated structures of octahedral sheet are similar to those of other dioctahedral clay minerals having 2:1 layer structure, that is, removal of 2OH- as H2O and relocation of residual O2- to the same level as that of the octahedral cations.

Ritter Reactions. I. Combined Intramolecular Cyclization and Amide Formation

1,5-Dimethylenecyclooctane (5) and 7,11-dimethylene-6,7,8,9-tetrahydro-5,9-propano-5H-benzocycloheptene (7) undergo efficient intramolecular cyclization and Ritter reaction in a one-flask procedure. Similarly,11-methylene-5,6,8,9-tetrahydro-5,9-propano-7H-benzocyclohepten-7-one (10) may be converted into cyclic hydroxy amide products. Alternatively, a combined intramolecular cyclization and double Ritter reaction with acetonitrile can be carried out to produce 7,9-bis( acetamido )-6,7,8,9,10,11-hexahydro-5,9:7,11-dimethano-5H-benzocyclononene monohydrate (12) whose crystal structure (C19 H24 N2 O2 H2O,P21/ca = 10.477(l), b = 14.595(1), c = 14.493(l) �, β =127.900(3)�, Z= 4) was determined with a final R = 0.039. Hydrogen-bonded dimeric units of the bis(amide) are surrounded by six water molecules which are involved in three different hydrogen-bonded arrangements. Mixed bis(amide) products may also be produced from (10) via the hydroxy amide, demonstrating that the bis(amide)(12) results from sequential Ritter reactions.

Experimental Evidence of N2 Formation from NO in Simulated Coal-fired Flue Gas by Electron Beam Irradiation

Abstract Nitrogen molecule formation was first observed experimentally in simulated coal-fired flue gas (NO–SO2–H2O–O2–N2) with the electron beam-ammonia treatment method in flow system. The increase of 29N2 was detected by mass-spectrometers in the flue gas containing N-15 labeled NO. The fraction of the 15NO converted to 29N2 was determined to be 23% at 14 kGy.

A GC-system for the analysis of residual geothermal gases

The gases evolved from geothermal fields, after condensation of H2O, CO2, H2S and NH3 in caustic solution, contain He, H2, Ar, O2, N2, CH4 and higher hydrocarbons. The analysis for the major components in these residual gas mixtures can be achieved by use of two simple gas chromatographs in parallel, and using 5A molecular sieve. The separation of He and H2 to baseline is achieved by using low temperatures (30°C) coupled with a relatively long column; and the difficult separation of Ar and O2 is achieved by use of a cryogenically cooled column. The use of switching valves to backflush and bypass columns ensures that a minimum time for analysis can be achieved whilst retaining baseline separations of the He/H2 and Ar/O2 pairs.

Structural study of surface tungstate in WO3Al2O3: Effects of Hydration and 18O Exchange

AbstractThe Raman spectra of a series of WO3AI2O3 catalysts containing 1‐30 wt‐% of WO3 were investigated with respect to the effect of O2 calcination and H2OD2O exposure. These studies showed that the frequencies of bands due to surface tungstate species can be shifted reversibly by as much as 6% of their values during alternate O2 calcination and H2O exposure cycles. The exchange of 18O for l6O in the surface tungstate was also investigated with Raman spectroscopy and ion‐scattering spectrometry. The results were used to assign Raman bands to fundamental vibrations of the surface tungstate and to propose a mechanism of interaction between H2O and the surface tungstate that hitherto has not been addressed for WO3AI2O3.

Self-deactivation of water vapor: Role of the dimer

Past efforts to interpret experimental data on the self-deactivation rate of the ν2 (1→0) vibrational mode of water vapor have been thwarted because of the attempt to fit the data to a single relaxation time. In a phenomenological theory proposed here the deactivation takes place by means of three parallel processes: (1) collisional de-excitation of the excited monomer, (2) a two-step reaction involving association and spontaneous redissociation of an H2O collision complex, and (3) spontaneous dissociation of the stably bound H2O dimer. In pure H2O and in mixtures without O2, the reaction rate for association of the collision complex is found to be very slow, and the remaining relaxation modes (1) and (3) are effectively decoupled. In mixtures of H2O–air and H2O–O2 the association rate of the complex increases strongly, suggesting that O2 serves as an effective ‘‘chaperon’’ for this reaction, and the relaxation modes of the monomer (1) and complex (2) become strongly coupled. Fourteen sets of past data, representing a wide variety of test conditions and experimental methods, both acoustical and nonacoustical, are organized into three groups—each corresponding to a relaxation mode predicted by the theory. An analysis of an ultrasonic absorption peak, based on process (3), yields values for the standard entropy and enthalpy of dissociation of the stably bound H2O dimer.

COMPLEX DYNAMIC BEHAVIOR IN THE CASE OF CO—NO—O2—H2O REACTION SYSTEM ON Pt/γAl2O3CATALYST

Abstract Self-sustained, isothermal oscillations in outlet species concentrations were observed under certain steady inlet conditions in the case of the CO—NO—O2—H2O reaction system on Pt/γAl2O3 catalyst in a fixed-bed tubuiar reactor. The oscillations were mostly aperiodic, and for fixed inlet concentrations of the other species, they occurred in a rather narrow window of inlet oxygen concentrations near the stoichiometric point. The amplitude and frequency of these oscillations were affected by temperature and by the inlet concenlrations of CO and NO. Systemalic experiments, conducted to understand the cause of these oscillations, revealed that the catalyst aging procedure and the presence of water vapor induced the complex dynamic behavior observed in the CO—NO—O2—H2O system. The oscillations are explained qualitatively in terms of the competition among the various reactants for adsorption and subsequent reaction on the catalyst surface.