scholarly journals Astrochemistry of Interstellar Clouds: II. Molecular Formation in a Contracting Cloud

1987 ◽  
Vol 120 ◽  
pp. 273-274
Author(s):  
M.A. El Shalaby ◽  
A. Aiad
Keyword(s):  
Gas Phase ◽  
Optical Depth ◽  
Chemical Reactions ◽  
Particle Density ◽  
Interstellar Cloud ◽  
Gas Phase Reactions ◽  
Interstellar Clouds ◽  
Continous Function ◽  
Molecular Formation ◽  
Self Gravity

The chemistry of an 667 Mo interstellar cloud was studied using 142 reactions for 40 species during the contraction under self gravity in two steps. At first the contraction is allowed without gas phase reactions untill certain optical depth is reached. Secondly, at this optical depth the chemical reactions are started for sufficient cycles in a time dependant scheme till only very small additionally changes in the abundances occur. The so obtained, relative abundances and coulmn densities for different species represent a continous function of the optical depths. The values arround τ=6.3 represent the observations for H2, H2+, H3+, OH, OH+, CH, CH+, CH2, CH2+, CH3+, H2O and H3O+. The region of τ between 1 and 5 i.e. of particle density between 4 102–6 103 is the preferable formation place for the majority of molecules.

scholarly journals Molecular Formation in Hot Diffuse Clouds

1980 ◽  
Vol 87 ◽  
pp. 273-280
Author(s):  
A. Dalgarno
Keyword(s):  
Gas Phase ◽  
Interstellar Clouds ◽  
Gas Phase Chemistry ◽  
Molecular Formation ◽  
Phase Chemistry ◽  
Diffuse Clouds

A description is given of the processes of molecular formation and destruction in diffuse interstellar clouds and detailed models of the clouds lying towards ζ Ophiuchi, ζ Persei and o Persei are used to assess the validity of gas phase chemistry. Modifications that may arise from shock-heated regions are discussed.

The Role of Starting Potential in the Kinetics of Chemical Reactions under Electrodeless Discharge

1970 ◽  
Vol 25 (11) ◽  
pp. 1772
Author(s):  
T.S.R Ao ◽  
A. Patil
Keyword(s):  
Gas Phase ◽  
Chemical Reactions ◽  
Electric Discharge ◽  
Specific Rate ◽  
Gas Phase Reactions ◽  
Electrodeless Discharge ◽  
First Order ◽  
Kinetics Of

Abstract It has been shown that in kinetically first order gas phase reactions occuring under electric discharge, such as the decomposition of N2O, the application, at various initial pressures, of the same multiple of the respective starting potential ensures that the reaction occurs at the same specific rate.

Global minimum profile error (GMPE) – a least-squares-based approach for extracting macroscopic rate coefficients for complex gas-phase chemical reactions

2018 ◽  
Vol 20 (2) ◽  
pp. 1231-1239 ◽  
Author(s):  
Minh v. Duong ◽  
Hieu T. Nguyen ◽  
Tam V.-T. Mai ◽  
Lam K. Huynh
Keyword(s):  
Master Equation ◽  
Least Squares ◽  
Gas Phase ◽  
Chemical Reactions ◽  
Global Minimum ◽  
Rate Coefficients ◽  
Gas Phase Reactions ◽  
Profile Error ◽  
Time Resolved ◽  
Phase Chemical

The new GMPE method was introduced to derive the macroscopic rate coefficients for complex gas-phase reactions from the time-resolved species profiles obtained from the master equation (ME) solutions.

Fire Plume Along Vertical Surfaces: Effect of Finite-Rate Chemical Reactions

1984 ◽  
Vol 106 (4) ◽  
pp. 713-720 ◽  
Author(s):  
C. H. Chen ◽  
J. S. T’ien
Keyword(s):  
Carbon Monoxide ◽  
Gas Phase ◽  
Chemical Reactions ◽  
Vertical Wall ◽  
Fire Plume ◽  
Gas Phase Reactions ◽  
Finite Rate ◽  
Slowing Down ◽  
Kinetic Rates ◽  
Relative Kinetic

Fire plume along a vertical wall is analyzed using a laminar boundary layer model, including finite-rate, gas-phase chemical kinetics. The chemical reactions include two semiglobal steps: In the first, fuel is oxidized to form carbon monoxide and water vapor, and in the second, carbon monoxide is oxidized to form carbon dioxide. Several important nondimensional kinetic parameters are identified and a parametric study is given. The computed results indicate that by slowing down the relative kinetic rates in the gas-phase reactions, the total surface heat transfer rate and the preheating distance are decreased. Furthermore, slowing down the kinetics also increases the amount of unreacted combustibles that escape from the flame.

Gas Phase Reactions in Horizontal MOCVD Reactors

1987 ◽  
Vol 94 ◽  
Author(s):  
Hitoshi Tanaka ◽  
J. Komeno
Keyword(s):  
Steady State ◽  
Gas Phase ◽  
Chemical Reactions ◽  
Chemical Species ◽  
Kinetic Simulation ◽  
Gas Phase Reactions ◽  
Mocvd Reactor

ABSTRACTWe have applied kinetic simulation to MOCVD chemistry in a horizontal MOCVD reactor. Both chemical reactions and material diffusion are considered. For trimethylgallium decomposition, concentrations of chemical species reach their steady state values which differ largely from the equilibrium values.

scholarly journals Crossed-beam chemical reaction dynamics probed with universal and state resolved ion imaging

2018 ◽  
Author(s):  
◽  
Alexander Kamasah
Keyword(s):  
Gas Phase ◽  
Chemical Reactions ◽  
Chemical Reaction ◽  
Reaction Dynamics ◽  
Reaction Cross ◽  
Translational Energy ◽  
Gas Phase Reactions ◽  
Chemical Reaction Dynamics ◽  
Products Of Reaction ◽  
State Selection

The main goal of chemical reaction dynamics is to unravel the intimate motions of individual atoms during a chemical transformation. This information must generally be inferred from indirect macroscopic measurement. Very important information such as translational energy dependence of the reaction cross-section, vibrational mode-specific promotion of reactivity, product angular and velocity distributions are normally extracted. Understanding how these chemical reactions occur at the microscopic level gives us a better insight in understanding reactive intermediates and products of reaction. For a better understanding of the elementary chemical reactions, it is imperative that the studies are performed under well-defined laboratory conditions. Over the last few decades, the field has witnessed unprecedented advances in both experiment and theory. Advancements in generating reactants, state selection, improvement of crossed-molecular beam machines and products detection have gone a long way to improve our ability in studying chemical reactions in the gas phase. In 1986, Hershbach,[1] Lee[2] , and Polayni[3] together shared the Nobel Prize in Chemistry for their work on the dynamics of gas phase reactions.

scholarly journals Molecule Formation in Cool, Dense Interstellar Clouds

1980 ◽  
Vol 87 ◽  
pp. 341-353 ◽  
Author(s):  
William D. Watson
Keyword(s):  
Gas Phase ◽  
Chemical Reactions ◽  
Molecular Species ◽  
Isotope Fractionation ◽  
Interstellar Molecules ◽  
Complex Molecules ◽  
Interstellar Clouds ◽  
Molecule Formation ◽  
Cloud Models ◽  
Gas Phase Ion

A discussion is given of the general processes and considerations that arise in attempting to understand molecular reactions in cool, dense interstellar clouds. Basic elements of the gas phase, “ion-molecule” scheme are given explicitly before surveying topics in which there is considerable current activity. These topics include: (i) refined comparisons of prediction and observation for species of “intermediate” complexity, (ii) numerical computations of cloud models which include numerous chemical reactions and molecular species, (iii) formation of the complex molecules, (iv) isotope fractionation in interstellar molecules and (v) possible contributions from chemistry in shocks.

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