Upper Limit for the Rate Coefficient for the Reaction HO2 + NO2 .fwdarw. HONO + O2

1995 ◽  
Vol 29 (1) ◽  
pp. 202-206 ◽  
Author(s):  
Geoffrey S. Tyndall ◽  
John J. Orlando ◽  
Jack G. Calvert
Keyword(s):  
Rate Coefficient ◽  
Upper Limit

scholarly journals Direct Kinetic Measurements and Master Equation Modelling of the Unimolecular Decomposition of Resonantly-Stabilized CH2CHCHC(O)OCH3 Radical and an Upper Limit Determination for CH2CHCHC(O)OCH3 + O2 Reaction

2020 ◽  
Vol 234 (7-9) ◽  
pp. 1251-1268 ◽  
Author(s):  
Satya Prakash Joshi ◽  
Prasenjit Seal ◽  
Timo Theodor Pekkanen ◽  
Raimo Sakari Timonen ◽  
Arrke J. Eskola
Keyword(s):  
Master Equation ◽  
Density Functional ◽  
Rate Coefficient ◽  
Decomposition Kinetics ◽  
Basis Sets ◽  
Stationary Points ◽  
Unimolecular Decomposition ◽  
Kinetic Measurements ◽  
Point Energy ◽  
Upper Limit

AbstractMethyl-Crotonate (MC, (E)-methylbut-2-enoate, CH3CHCHC(O)OCH3) is a potential component of surrogate fuels that aim to emulate the combustion of fatty acid methyl ester (FAME) biodiesels with significant unsaturated FAME content. MC has three allylic hydrogens that can be readily abstracted under autoignition and combustion conditions to form a resonantly-stabilized CH2CHCHC(O)OCH3 radical. In this study we have utilized photoionization mass spectrometry to investigate the O2 addition kinetics and thermal unimolecular decomposition of CH2CHCHC(O)OCH3 radical. First we determined an upper limit for the bimolecular rate coefficient of CH2CHCHC(O)OCH3 + O2 reaction at 600 K (k ≤ 7.5 × 10−17 cm3 molecule−1 s−1). Such a small rate coefficient suggest this reaction is unlikely to be important under combustion conditions and subsequent efforts were directed towards measuring thermal unimolecular decomposition kinetics of CH2CHCHC(O)OCH3 radical. These measurements were performed between 750 and 869 K temperatures at low pressures (<9 Torr) using both helium and nitrogen bath gases. The potential energy surface of the unimolecular decomposition reaction was probed at density functional (MN15/cc-pVTZ) level of theory and the electronic energies of the stationary points obtained were then refined using the DLPNO-CCSD(T) method with the cc-pVTZ and cc-pVQZ basis sets. Master equation simulations were subsequently carried out using MESMER code along the kinetically important reaction pathway. The master equation model was first optimized by fitting the zero-point energy corrected reaction barriers and the collisional energy transfer parameters $\Delta{E_{{\text{down}},\;{\text{ref}}}}$ and n to the measured rate coefficients data and then utilize the constrained model to extrapolate the decomposition kinetics to higher pressures and temperatures. Both the experimental results and the MESMER simulations show that the current experiments for the thermal unimolecular decomposition of CH2CHCHC(O)OCH3 radical are in the fall-off region. The experiments did not provide definite evidence about the primary decomposition products.

REACTION OF N2(A3∑U+) WITH ATOMIC NITROGEN

1966 ◽  
Vol 44 (10) ◽  
pp. 1171-1174 ◽  
Author(s):  
Robert A. Young
Keyword(s):  
Excited States ◽  
Rate Coefficient ◽  
Atomic Nitrogen ◽  
Active Nitrogen ◽  
Upper Limit ◽  
Interchange Process

Attempts to measure the actual lifetime of N2(A3∑u+) in active nitrogen resulted only in a very small upper limit of ≈5 × 10−4 s. This result is consistent with quenching of the A3∑u+ state by atomic nitrogen in an atom–atom interchange process,[Formula: see text]having a rate coefficient of [Formula: see text] It is suggested that similar processes are involved in determining the distribution of excited states observed in atom association.

An upper limit for the rate coefficient of the reaction of NH2radicals with O2using FTIR product analysis

1991 ◽  
Vol 96 (D11) ◽  
pp. 20761 ◽  
Author(s):  
G. S. Tyndall ◽  
J. J. Orlando ◽  
K. E. Nickerson ◽  
C. A. Cantrell ◽  
J. G. Calvert
Keyword(s):  
Rate Coefficient ◽  
Product Analysis ◽  
Upper Limit

Upper limit for the rate coefficient for the reaction of OH with N2O5

2000 ◽  
Vol 2 (18) ◽  
pp. 4045-4048 ◽  
Author(s):  
Mary K. Gilles ◽  
A. R. Ravishankara
Keyword(s):  
Rate Coefficient ◽  
Upper Limit

scholarly journals In-cloud processes of methacrolein under simulated conditions – Part 1: Aqueous phase photooxidation

2009 ◽  
Vol 9 (14) ◽  
pp. 5093-5105 ◽  
Author(s):  
◽  
I. El Haddad ◽  
M. Scarfogliero ◽  
L. Nieto-Gligorovski ◽  
B. Temime-Roussel ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Aqueous Phase ◽  
Rate Coefficient ◽  
Cloud Droplet ◽  
Total Carbon ◽  
Main Reaction ◽  
Reaction Products ◽  
Primary Reaction ◽  
Carbon Yield ◽  
Upper Limit

Abstract. The photooxidation of methacrolein was studied in the aqueous phase under simulated cloud droplet conditions. The obtained rate constant of OH-oxidation of methacrolein at 6°C in unbuffered solutions was 5.8(±0.9)×109 M−1 s−1. The measured rate coefficient is consistent with OH-addition on the C=C bond. This was confirmed by the mechanism established on the study of the reaction products (at 25°C in unbuffered solutions) where methylglyoxal, formaldehyde, hydroxyacetone and acetic acid/acetate were the main reaction products. An upper limit for the total carbon yield was estimated to range from 53 to 85%, indicating that some reaction products remain unidentified. A possible source of this mismatch is the formation of higher molecular weight compounds as primary reaction products which are presented in El Haddad et al. (2009) and Michaud et al. (2009).

Redetermination of the rate coefficient for the reaction of O(1D) with N2

2002 ◽  
Vol 29 (15) ◽  
Author(s):  
A. R. Ravishankara
Keyword(s):  
Rate Coefficient
Sign in / Sign up

Export Citation Format

Share Document