scholarly journals Experimental studies of surface reactions among OH radicals that yield H2O and CO2 at 40–60 K

2011 ◽  
Vol 13 (35) ◽  
pp. 15792 ◽  
Author(s):  
Yasuhiro Oba ◽  
Naoki Watanabe ◽  
Akira Kouchi ◽  
Tetsuya Hama ◽  
Valerio Pirronello
Keyword(s):  
Surface Reactions ◽  
Experimental Studies ◽  
Oh Radicals

FORMATION OF CARBONIC ACID (H2CO3) BY SURFACE REACTIONS OF NON-ENERGETIC OH RADICALS WITH CO MOLECULES AT LOW TEMPERATURES

2010 ◽  
Vol 722 (2) ◽  
pp. 1598-1606 ◽  
Author(s):  
Yasuhiro Oba ◽  
Naoki Watanabe ◽  
Akira Kouchi ◽  
Tetsuya Hama ◽  
Valerio Pirronello
Keyword(s):  
Low Temperatures ◽  
Carbonic Acid ◽  
Surface Reactions ◽  
Oh Radicals

scholarly journals Editorial for Special Issue “Mineral Surface Reactions at the Nanoscale”

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 185
Author(s):  
Christine Putnis
Keyword(s):  
Surface Reactions ◽  
Experimental Studies ◽  
Analytical Techniques ◽  
Aqueous Fluid ◽  
Mineral Surfaces ◽  
Special Issue ◽  
Mineral Surface ◽  
Electron Microscopies ◽  
Interface Control ◽  
The Earth

Reactions at mineral surfaces are central to all geochemical processes. As minerals comprise the rocks of the Earth, the processes occurring at the mineral–aqueous fluid interface control the evolution of the rocks and, hence, the structure of the crust of the Earth during such processes at metamorphism, metasomatism, and weathering. In recent years, focus has been concentrated on mineral surface reactions made possible through the development of advanced analytical techniques, such as atomic force microscopy (AFM), advanced electron microscopies (SEM and TEM), phase shift interferometry, confocal Raman spectroscopy, advanced synchrotron-based applications, complemented by molecular simulations, to confirm or predict the results of experimental studies. In particular, the development of analytical methods that allow direct observations of mineral–fluid reactions at the nanoscale have revealed new and significant aspects of the kinetics and mechanisms of reactions taking place in fundamental mineral–fluid systems. These experimental and computational studies have enabled new and exciting possibilities to elucidate the mechanisms that govern mineral–fluid reactions, as well as the kinetics of these processes, and, hence, to enhance our ability to predict potential mineral behavior. In this Special Issue “Mineral Surface Reactions at the Nanoscale”, we present 12 contributions that highlight the role and importance of mineral surfaces in varying fields of research.

Aerothermochemistry of Metal Erosion by Hot Reactive Gases

1978 ◽  
Vol 100 (3) ◽  
pp. 531-536 ◽  
Author(s):  
A. Gany ◽  
L. H. Caveny ◽  
M. Summerfield
Keyword(s):  
Surface Reactions ◽  
Experimental Studies ◽  
Heating Surface ◽  
Melting Rate ◽  
Short Exposure ◽  
Convective Heating ◽  
Erosion Rates ◽  
Diffusion Limited ◽  
O2 Concentration ◽  
Reactive Gases

Analytical studies were conducted to investigate the mechanisms of metal erosion produced by short exposures (< 2 ms) to flowing high pressure (∼ 350 MPa), high temperature (∼ 3000 K) reactive gases. Previous experimental studies established that the intense heating during the short exposure produced melting and, when reactive gases were used, oxidation of the surface and enhanced erosion. The reactions were modeled as diffusion-limited, heterogeneous surface reactions which achieved equilibrium at the gas/metal interface. Calculated results for the sequential events of initial heating, surface reactions, and melting explained and correlated the experimental trends for Fe, Al, Ti, and Mo. Rapidly increasing erosion rates with increasing O2 concentration are the result of the surface reactions between the metal and O2. As O2 concentration increases, the heating produced by the surface reaction exceeds the forced convective heating which, in turn, greatly enhances the melting rate.

Comparative study of the growth characteristics and electrical properties of atomic-layer-deposited HfO2 films obtained from metal halide and amide precursors

2018 ◽  
Vol 6 (27) ◽  
pp. 7367-7376 ◽  
Author(s):  
Il-Kwon Oh ◽  
Bo-Eun Park ◽  
Seunggi Seo ◽  
Byung Chul Yeo ◽  
Jukka Tanskanen ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Comparative Study ◽  
Film Growth ◽  
Surface Reactions ◽  
Experimental Studies ◽  
Atomic Layer ◽  
Growth Characteristics ◽  
Metal Halide

Theoretical and experimental studies were performed on surface reactions during film growth and electrical properties of HfO2 using two different Hf precursors, HfCl4 and Hf(N(CH3)2)4.

scholarly journals Modelling the formation and composition of secondary organic aerosol from α- and β-pinene ozonolysis using MCM v3

2004 ◽  
Vol 4 (3) ◽  
pp. 2905-2948 ◽  
Author(s):  
M. E. Jenkin
Keyword(s):  
Secondary Organic Aerosol ◽  
Experimental Studies ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Oh Radicals ◽  
Product Distributions ◽  
Wide Range ◽  
Partitioning Coefficients ◽  
Detailed Composition ◽  
Multifunctional Products

Abstract. The formation and detailed composition of secondary organic aerosol (SOA) from the gas phase ozonolysis of α- and β-pinene has been simulated using the Master Chemical Mechanism version 3 (MCM v3), coupled with a representation of gas-to-aerosol transfer of semivolatile and involatile oxygenated products. A kinetics representation, based on equilibrium absorptive partitioning of ca. 200 semivolatile products, was found to provide an acceptable description of the final mass concentrations observed in a number of reported laboratory and chamber experiments, provided partitioning coefficients were increased by about two orders of magnitude over those defined on the basis of estimated vapour pressures. This adjustment is believed to be due, at least partially, to the effect of condensed phase association reactions of the partitioning products. Even with this adjustment, the simulated initial formation of SOA was delayed relative to that observed, implying the requirement for the formation of species of much lower volatility to initiate SOA formation. The inclusion of a simplified representation of the formation and gas-to-aerosol transfer of involatile dimers of 22 bi- and multifunctional carboxylic acids (in addition to the absorptive partitioning mechanism) allowed a much improved description of SOA formation for a wide range of conditions. The simulated SOA composition recreates certain features of the product distributions observed in a number of experimental studies, but implies an important role for multifunctional products containing hydroperoxy groups (i.e. hydroperoxides). This is particularly the case for experiments in which 2-butanol is used to scavenge OH radicals, because [HO2]/[RO2] ratios are elevated in such systems. The optimized mechanism is used to calculate SOA yields from α- and β-pinene ozonolysis in the presence and absence of OH scavengers, and as a function of temperature.

A Kinetic Model for Metalorganic Chemical Vapor Deposition of GaAs from Trimethylgallium and Arsine

1988 ◽  
Vol 131 ◽  
Author(s):  
Triantafillos J. Mountziaris ◽  
Klavs F. Jensen
Keyword(s):  
Chemical Vapor Deposition ◽  
Kinetic Model ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Transport Model ◽  
Surface Reactions ◽  
Experimental Studies ◽  
Chemical Vapor ◽  
Metalorganic Chemical

ABSTRACTA kinetic model for metalorganic chemical vapor deposition (MOCVD) of GaAs from trimethylgallium and arsine is presented. The proposed mechanism includes 15 gas-phase species, 17 gas-phase reactions, 9 surface species and 29 surface reactions. The surface reactions take into account different crystallographic orientations of the GaAs substrate. Sensitivity analysis and existing experimental observations have been used to develop the reduced mechanism from the large number of reactions that might in principle occur. Rate constants are estimated by using thermochemical methods and reported experimental data. The kinetic mechanism is combined with a two-dimensional transport model of a hot-wall tubular reactor used in experimental studies. Model predictions of gas-phase composition and GaAs growth rates show good agreement with published experimental studies. In addition, the model predicts reported trends in carbon incorporation.

Experimental studies of the oscillatory combustion of hydrogen in a stirred flow reactor

1991 ◽  
Vol 337 (1646) ◽  
pp. 199-210 ◽  
Keyword(s):  
Maximum Concentration ◽  
Flow Reactor ◽  
Multiphoton Ionization ◽  
Experimental Studies ◽  
Oh Radicals ◽  
Hydrogen Atoms ◽  
Numerical Studies ◽  
Electronically Excited ◽  
Combustion Of Hydrogen ◽  
Oscillatory Combustion

Experimental studies of the phase relations between H atoms, OH radicals and reactant temperature during the gas-phase, oscillatory combustion of hydrogen in a well-stirred flow reactor are reported. Absolute concentrations of the OH radical and the reactant temperature were measured in absorption from the vibrational-rotational structure of the laser-induced, electronically excited, OH spectrum . Relative concentrations of H atoms were obtained by multiphoton ionization, also induced by a laser. The hydrogen atoms reached their maximum concentration first during the oscillatory combustion, rising to a sharp peak followed by a rapid decay within several milliseconds. The OH radicals reached their maximum concentration about 1 ms after the H atoms. The maximum of the reactant temperature was in phase with the hydroxyl radicals. Experimental and numerical studies of the interaction that occurs between oscillations in a pair of coupled reactors are also presented.

scholarly journals EFFECT OF MOISTURE ON NITROGEN DIOXIDE FORMATION IN LAMINAR FLAME OF NATURAL GAS

2021 ◽  
Vol 29 (3) ◽  
pp. 287-297
Author(s):  
Aleksandr Sigal ◽  
Dmitri Paderno
Keyword(s):  
Natural Gas ◽  
Nitrogen Dioxide ◽  
Laminar Flame ◽  
Combustion Process ◽  
Experimental Studies ◽  
Oh Radicals ◽  
Excess Moisture ◽  
Effect Of Moisture ◽  
Cylindrical Steel ◽  
Oxidation Of No

The paper contains the results of experimental studies of the effect of moisture on nitrogen dioxide formation and on oxidation of NO to NO2 in laminar premixed flame of natural gas. The water vapor is shown to be the third very influential participant, along with fuel and oxidizer, in the combustion process. Injection of moisture into the combustion zone has an effect due to the insertion of additional quantities of HO2- and OH– radicals into the process, which contributes to the intensification of the oxidation of NO to NO2. Introduction of the concept of the “excess moisture ratio” in the combustion process is proposed. The studies were executed at the laboratory installation in conditions of formation of the V-shaped laminar flame of natural gas behind a transverse cylindrical steel stabilizer, with determining the concentrations of flue gas components.

scholarly journals Comment on “Atmospheric chemistry of oxazole: the mechanism and kinetic studies on oxidation reaction initiated by OH radicals” by A. Shiroudi, M. A. Abdel-Rahman, A. M. El-Nahas and M. Altarawneh, New J. Chem., 2021, 45, 2237

2021 ◽  
Author(s):  
Tam V.-T. Mai ◽  
Lam K. Huynh
Keyword(s):  
Master Equation ◽  
Atmospheric Chemistry ◽  
Oxidation Reaction ◽  
Experimental Studies ◽  
Kinetic Studies ◽  
Oh Radicals ◽  
Rate Model

The large kinetic discrepancy between computational and experimental studies is resolved using the rigorous stochastic RRKM-based master-equation rate model. Detailed mechanistic insights are also revealed to advance its related applications.

scholarly journals Modelling the formation and composition of secondary organic aerosol from α- and β-pinene ozonolysis using MCM v3

2004 ◽  
Vol 4 (7) ◽  
pp. 1741-1757 ◽  
Author(s):  
M. E. Jenkin
Keyword(s):  
Secondary Organic Aerosol ◽  
Experimental Studies ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Oh Radicals ◽  
Product Distributions ◽  
Wide Range ◽  
Partitioning Coefficients ◽  
Detailed Composition ◽  
Multifunctional Products

Abstract. The formation and detailed composition of secondary organic aerosol (SOA) from the gas phase ozonolysis of α- and β-pinene has been simulated using the Master Chemical Mechanism version 3 (MCM v3), coupled with a representation of gas-to-aerosol transfer of semivolatile and involatile oxygenated products. A kinetics representation, based on equilibrium absorptive partitioning of ca. 200 semivolatile products, was found to provide an acceptable description of the final mass concentrations observed in a number of reported laboratory and chamber experiments, provided partitioning coefficients were increased by about two orders of magnitude over those defined on the basis of estimated vapour pressures. This adjustment is believed to be due, at least partially, to the effect of condensed phase association reactions of the partitioning products. Even with this adjustment, the simulated initial formation of SOA was delayed relative to that observed, implying the requirement for the formation of species of much lower volatility to initiate SOA formation. The inclusion of a simplified representation of the formation and gas-to-aerosol transfer of involatile dimers of 22 bi- and multifunctional carboxylic acids (in addition to the absorptive partitioning mechanism) allowed a much improved description of SOA formation for a wide range of conditions. The simulated SOA composition recreates certain features of the product distributions observed in a number of experimental studies, but implies an important role for multifunctional products containing hydroperoxy groups (i.e. hydroperoxides). This is particularly the case for experiments in which 2-butanol is used to scavenge OH radicals, because [HO2]/[RO2] ratios are elevated in such systems. The optimized mechanism is used to calculate SOA yields from α- and β-pinene ozonolysis in the presence and absence of OH scavengers, and as a function of temperature.

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