Rate Constants for the Gas-Phase Reactions of the OH Radical with Dichlorobiphenyls, 1-Chlorodibenzo-p-dioxin, 1,2-Dimethoxybenzene, and Diphenyl Ether: Estimation of OH Radical Reaction Rate Constants for PCBs, PCDDs, and PCDFs

1995 ◽  
Vol 29 (6) ◽  
pp. 1591-1598 ◽  
Author(s):  
Eric S. C. Kwok ◽  
Roger. Atkinson ◽  
Janet. Arey
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Reaction Rate ◽  
Diphenyl Ether ◽  
Radical Reaction ◽  
Oh Radical ◽  
Gas Phase Reactions ◽  
Reaction Rate Constants

scholarly journals The role of atom tunneling in gas-phase reactions in planet-forming disks

2019 ◽  
Vol 627 ◽  
pp. A45 ◽  
Author(s):  
J. Meisner ◽  
I. Kamp ◽  
W.-F. Thi ◽  
J. Kästner
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Reaction Rate ◽  
Tunneling Effect ◽  
Gas Phase Reactions ◽  
Disk Model ◽  
Reaction Rate Constants ◽  
T Tauri ◽  
Simple Molecules ◽  
The Impact

Context. Chemical Gas-phase reactions of simple molecules have been recently revised to include atom tunneling at very low temperatures. This paper investigates the impact of the increased reaction rate constant due to tunneling effects on planet-forming disks. Aims. Our aim is to quantify the astrophysical implications of atom tunneling for simple molecules that are frequently used to infer disk structure information or to define the initial conditions for planet (atmosphere) formation. Methods. We quantify the tunneling effect on reaction rate constants by using H2 + OH → H2O + H as a scholarly example in comparison to previous UMIST2012 rate constants. In a chemical network with 1299 reactions, we identify all chemical reactions that could show tunneling effects. We devise a simple formulation of reaction rate constants that overestimates tunneling and screen a standard T Tauri disk model for changes in species abundances. For those reactions found to be relevant, we find values of the most recent literature for the rate constants including tunneling and compare the resulting disk chemistry to the standard disk model(s), a T Tauri and a Herbig disk. Results. The rate constants in the UMIST2012 database in many cases already capture tunneling effects implicitly, as seen in the curvature of the Arrhenius plots of some reactions at low temperature. A rigorous screening procedure identified three neutral-neutral reactions where atom tunneling could change simple molecule abundances. However, by adopting recent values of the rate constants of these reactions and due to the layered structure of planet-forming disks, the effects are limited to a small region between the ion-molecule dominated regime and the ice reservoirs where cold (<250 K) neutral-neutral chemistry dominates. Abundances of water close to the midplane snowline can increase by a factor of two at most compared to previous results with UMIST2012 rates. Observables from the disk surface, such as high excitation (>500 K) water line fluxes, decrease by 60% at most when tunneling effects are explicitly excluded. On the other hand, disk midplane quantities relevant for planet formation such as the C-to-O ratio and also the ice-to-rock ratio are clearly affected by these gas-phase tunneling effects.

Aqueous OH Radical Reaction Rate Constants for Organophosphorus Flame Retardants and Plasticizers: Experimental and Modeling Studies

2018 ◽  
Vol 52 (5) ◽  
pp. 2790-2799 ◽  
Author(s):  
Chao Li ◽  
Gaoliang Wei ◽  
Jingwen Chen ◽  
Yuanhui Zhao ◽  
Ya-Nan Zhang ◽  
...  
Keyword(s):  
Rate Constants ◽  
Flame Retardants ◽  
Reaction Rate ◽  
Radical Reaction ◽  
Oh Radical ◽  
Reaction Rate Constants ◽  
Modeling Studies ◽  
Organophosphorus Flame Retardants

Estimation of ⋅OH radical reaction rate constants for phenol and chlorinated phenols using UV/H2O2 photo-oxidation

1999 ◽  
Vol 64 (1) ◽  
pp. 91-104 ◽  
Author(s):  
Asim K. De ◽  
Basab Chaudhuri ◽  
Sekhar Bhattacharjee ◽  
Binay K. Dutta
Keyword(s):  
Rate Constants ◽  
Reaction Rate ◽  
Radical Reaction ◽  
Oh Radical ◽  
Chlorinated Phenols ◽  
Photo Oxidation ◽  
Reaction Rate Constants
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