Pressure Dependence of Rate Coefficients for Formation and Dissociation of Pentachlorodisilane and Related Chemical Activation Reactions

2017 ◽  
Vol 49 (8) ◽  
pp. 584-595
Author(s):  
Kaito Noda ◽  
Nílson Kunioshi ◽  
Akio Fuwa
Keyword(s):  
Pressure Dependence ◽  
Chemical Activation ◽  
Rate Coefficients

Gas-Phase Kinetics of the Reactions of the CH2F Radicals with the Radicals CHF2, CH3, and C2H5

2004 ◽  
Vol 218 (4) ◽  
pp. 493-510 ◽  
Author(s):  
T. Beiderhase ◽  
Karlheinz Hoyermann ◽  
Jörg Nothdurft ◽  
Matthias Olzmann
Keyword(s):  
Flow Reactor ◽  
Chemical Activation ◽  
Multiphoton Ionization ◽  
Rate Coefficients ◽  
Cross Combination ◽  
Time Profiles ◽  
Gas Phase Kinetics ◽  
Stable Species ◽  
Activation Mechanisms ◽  
Kinetics Of

AbstractThe mechanisms and the rates of the reactions of the fluorinated hydrocarbon radical CH2F with the fluorinated and pure hydrocarbon radicals CHF2, CH3, and C2H5, respectively, have been studied at low pressure (around 2 mbar) and room temperature using the discharge-flow reactor technique. Mass spectrometry either with electron impact or laser induced multiphoton ionization was applied for the detection of labile and stable species. The cross combination of the radicals is mainly followed by HF elimination from the chemically activated adduct. The overall rate coefficients at 298K forCH2F + CHF2 → C2H2F2 + HF (1)CH2F + CH3 → C2H4 + HF (2)CH2F + C2H5 → C3H6 + HF (3) were derived from the analysis of the radical-time profiles by fit procedures; the following values were obtained:CH2F + CHF2 → C2H2F2 + HF (1)CH2F + CH3 → C2H4 + HF (2)CH2F + C2H5 → C3H6 + HF (3)k1 = (3.0 + 1.5/ − 0.7) × 1012cm3mol−1s−1k2 = (4.0 ± 1.5) × 1013cm3mol−1s−1k3 = (9.0 ± 3) × 1012cm3mol−1s−1.The results are discussed in terms of chemical activation mechanisms.

scholarly journals Third excimer continua in neon and argon

1993 ◽  
Vol 11 (3) ◽  
pp. 521-528 ◽  
Author(s):  
W. Krötz ◽  
A. Ulrich ◽  
B. Busch ◽  
G. Ribitzki ◽  
J. Wieser
Keyword(s):  
Pressure Dependence ◽  
Vacuum Ultraviolet ◽  
Rate Coefficient ◽  
Time Windows ◽  
Radiative Lifetime ◽  
Bimolecular Reaction ◽  
Rate Coefficients ◽  
Continuum Emission ◽  
Ultraviolet Emission ◽  
The Third

The emission of the third continuum of argon in the wavelength range between 175 and 250 nm and the vacuum ultraviolet emission of neon (λ < 100 nm) has been studied by timeresolved optical spectroscopy. The target gases at pressures between 2 and 100 kPa were excited with a pulsed beam of 100 MeV 32S9+ ions from the Munich Tandem van de Graaf accelerator. Wavelength spectra recorded in different time windows after the 2-ns beam pulses show that two different components contribute to the third continuum of argon. A radiative lifetime of 5.71 ± 0.08 ns for the Ar22+ molecule and a rate coefficient k3 = (1.46 ± 0.12) x 10-30 cm6/s for the reaction Ar2+ + 2Ar → Ar22+ + Ar were obtained from the pressure dependence of time spectra at a wavelength of 190 nm. From time- and pressure-dependent studies of the third continuum emission of neon at a wavelength of 99 nm, rate coefficients k2 = (3.6 ± 0.3) x 10-13 cm3/s for the bimolecular reaction Ne2+ + Ne→ 2Ne+ and k3 = (2.84 ± 0.09) X 10-31 cm6/s for the termolecular reaction Ne2+ + 2Ne → Ne22+ + Ne were determined.

scholarly journals Temperature-(208–318 K) and pressure-(18–696 Torr) dependent rate coefficients for the reaction between OH and HNO<sub>3</sub>

2018 ◽  
Vol 18 (4) ◽  
pp. 2381-2394 ◽  
Author(s):  
Katrin Dulitz ◽  
Damien Amedro ◽  
Terry J. Dillon ◽  
Andrea Pozzer ◽  
John N. Crowley
Keyword(s):  
Cross Sections ◽  
Pressure Dependence ◽  
Low Temperatures ◽  
Room Temperature ◽  
Rate Coefficients ◽  
Title Reaction ◽  
Data Set ◽  
Dependent Rate ◽  
Temperature And Pressure

Abstract. Rate coefficients (k5) for the title reaction were obtained using pulsed laser photolytic generation of OH coupled to its detection by laser-induced fluorescence (PLP–LIF). More than 80 determinations of k5 were carried out in nitrogen or air bath gas at various temperatures and pressures. The accuracy of the rate coefficients obtained was enhanced by in situ measurement of the concentrations of both HNO3 reactant and NO2 impurity. The rate coefficients show both temperature and pressure dependence with a rapid increase in k5 at low temperatures. The pressure dependence was weak at room temperature but increased significantly at low temperatures. The entire data set was combined with selected literature values of k5 and parameterised using a combination of pressure-dependent and -independent terms to give an expression that covers the relevant pressure and temperature range for the atmosphere. A global model, using the new parameterisation for k5 rather than those presently accepted, indicated small but significant latitude- and altitude-dependent changes in the HNO3 ∕ NOx ratio of between −6 and +6 %. Effective HNO3 absorption cross sections (184.95 and 213.86 nm, units of cm2 molecule−1) were obtained as part of this work: σ213.86  =  4.52−0.12+0.23  ×  10−19 and σ184.95  =  1.61−0.04+0.08  ×  10−17.

Kinetic Analysis of Complex Chemical Activation and Unimolecular Dissociation Reactions using QRRK Theory and the Modified Strong Collision Approximation

2000 ◽  
Vol 214 (11) ◽  
Author(s):  
A.Y. Chang ◽  
J.W. Bozzelli ◽  
A.M. Dean
Keyword(s):  
Chemical Activation ◽  
Peroxy Radical ◽  
Dissociation Rate ◽  
Rate Coefficients ◽  
Unimolecular Dissociation ◽  
Frequency Model ◽  
Dependent Rate ◽  
Vinyl Radical ◽  
Temperature And Pressure ◽  
Collision Approximation

A method to predict temperature and pressure-dependent rate coefficients for complex bimolecular chemical activation and unimolecular dissociation reactions is described. A three-frequency version of QRRK theory is developed and collisional stabilization is estimated using the modified strong-collision approximation. The methodology permits analysis of reaction systems with an arbitrary degree of complexity in terms of the number of isomer or product channels. Specification of both high and low pressure limits is also provided. The chemically activated reaction of vinyl radical with molecular oxygen is used to demonstrate the approach. Subsequent dissociation of the stabilized vinyl peroxy radical is used to illustrate prediction of dissociation rate coefficients. These calculations confirm earlier results that the vinoxy + O channel is dominant under combustion conditions. The results are also consistent with RRKM results using the same input conditions. This approach provides a means to provide reasonably accurate predictions of the rate coefficients that are required in many detailed mechanisms. The major advantage is the ability to provide reasonable estimates of rate coefficients for many complex systems where detailed information about the transition states is not available. It is also shown that a simpler 1-frequency model appears adequate for high temperature conditions.

Rate coefficients for the gas-phase reaction of OH radicals with dimethyl sulfide: temperature and O2partial pressure dependence

2006 ◽  
Vol 8 (6) ◽  
pp. 728-736 ◽  
Author(s):  
Mihaela Albu ◽  
Ian Barnes ◽  
Karl H. Becker ◽  
Iulia Patroescu-Klotz ◽  
Raluca Mocanu ◽  
...  
Keyword(s):  
Gas Phase ◽  
Pressure Dependence ◽  
Dimethyl Sulfide ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Gas Phase Reaction
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