Real-time observation of :CF2 formation in the infrared multiple-photon dissociation of fluoroform-d

Sarkar, S.K.; Palit, Dipak K.; Rao, K. V. S. Rama; Mittal, Jai P.

doi:10.1016/0009-2614(86)87155-x

Cited by 16 publications

(3 citation statements)

References 28 publications

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“…However, in the presence of CBrF 3 , the concentration of CH 3 radicals which can consume CF 2 such as (R6) and (R7) is much higher. It is estimated that rate constant for CF 2 dimerization is roughly 4 × 10 10 cm 3 mol −1 s −1 [42,43]. Previous studies have shown that the rate constant for CF 2 + CH 3 → CH 2 CF 2 + H can be well approximated by the expression 2 × 10 13 T −0.207 cm 3 mol −1 s −1 , which is significantly higher than that of CF 2 dimerization [35] and thus in the case where CBrF 3 is present, the rate of activation of CH 4 , is enhanced, the concentration of CH 3 is increased and thus the rate of formation of CH 2 CF 2 is higher.…”

Section: Mechanistic Analysis and Modellingmentioning

confidence: 99%

Conversion of CHF3 to CH2CF2 via reaction with CH4 in the presence of CBrF3: An experimental and kinetic modelling study

Han

Kennedy

Mackie

et al. 2010

Journal of Hazardous Materials

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Section: Mechanistic Analysis and Modellingmentioning

confidence: 99%

Conversion of CHF3 to CH2CF2 via reaction with CH4 in the presence of CBrF3: An experimental and kinetic modelling study

Han

Kennedy

Mackie

et al. 2010

Journal of Hazardous Materials

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“…In other dissociation experiments, such as refs − , oversimplified assumptions about the pressure dependence of reaction were made. The problem of the pressure dependence did not have to be accounted for in most of the recombination studies, such as refs and − , which were generally performed under conditions such that limiting high-pressure, second-order behavior was observed. It is the second goal of the present work to analyze the available dissociation and recombination data in terms of unimolecular rate theory.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Modeling Study of the Reaction C₂F₄ (+ M) ⇔ CF₂ + CF₂ (+ M)

et al. 2013

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The thermal dissociation reaction C2F4(+ M) → 2CF2(+ M) was studied in shock waves monitoring CF2 radicals by their UV absorption. The absorption coefficients as functions of wavelength and temperature were redetermined and are represented in analytical form. Dissociation rate constants as functions of bath gas concentration [M] and temperature, from previous and the present work, are presented analytically employing falloff expressions from unimolecular rate theory. Equilibrium constants are determined between 1200 and 1500 K. The data are shown to be consistent, with a C-C bond energy of 67.5 (±0.5) kcal mol(-1). High-pressure limiting rate constants for dissociation and recombination are found to be unusually small. This phenomenon can be attributed to an unusually pronounced anisotropy of the potential energy surface, such as demonstrated by quantum-chemical calculations of the potential energy surface.

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“…Experimental data have been gathered on this prototypical reaction over a long period (33)(34)(35)(36)(37)(38)(39)(40); recently, reliable experimental rate constants have become available through the work of Troe and coworkers (41,42), which provides us an opportunity to test our theoretical methods. In this work, the necessary physical parameters for treating the pressure dependence of collisional activation (43)(44)(45)(46)(47)(48)(49)(50) are directly taken from the literature; in the high-pressure limit, no empirical parameters are adjusted to the experimental data, and our calculations are from first principles.…”

Section: Significancementioning

confidence: 99%

Barrierless association of CF ₂ and dissociation of C ₂ F ₄ by variational transition-state theory and system-specific quantum Rice–Ramsperger–Kassel theory

Bao

Zhang

Truhlar

2016

Proc. Natl. Acad. Sci. U.S.A.

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Bond dissociation is a fundamental chemical reaction, and the first principles modeling of the kinetics of dissociation reactions with a monotonically increasing potential energy along the dissociation coordinate presents a challenge not only for modern electronic structure methods but also for kinetics theory. In this work, we use multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) to compute the highpressure limit dissociation rate constant of tetrafluoroethylene (C 2 F 4 ), in which the potential energies are computed by direct dynamics with the M08-HX exchange correlation functional. To treat the pressure dependence of the unimolecular rate constants, we use the recently developed system-specific quantum Rice-Ramsperger-Kassel theory. The calculations are carried out by direct dynamics using an exchange correlation functional validated against calculations that go beyond coupled-cluster theory with single, double, and triple excitations. Our computed dissociation rate constants agree well with the recent experimental measurements.bond dissociation | barrierless reaction | variable-reaction-coordinate variational transition-state theory | falloff | system-specific quantum RRK theory B ond breaking and association of fragments to make new bonds are two of the most fundamental processes in chemistry. Gas-phase bond dissociation and radical-radical association reactions are of great importance in combustion and plasma chemistry and atmospheric chemistry. Accurately describing the energetics and kinetics of these processes in a practical way for mechanistic analysis offers great challenges to modern theoretical chemistry.The electronic structure of closed-shell singlets can often be described to a good approximation by a single configuration state function (CSF); such systems are called single-reference systems, and methods using a single CSF as a reference function are called single-reference methods. Bond dissociation is usually an intrinsically multiconfigurational problem, often called a multireference problem (1). Coupled cluster (CC) theory (2, 3), as a high-level single-reference wave function method, is able to provide fairly accurate energies for bond-dissociation processes only if a high-enough excitation level (such as quadruple excitations) is used for the cluster operatorT; however, lack of such expensive higher excitation operators in CC calculations [such as in the case of coupled-cluster theory with single and double excitations (CCSD) (4)] can lead to a significant unphysical bump (5, 6) in the potential energy curve for dissociation. Kohn-Sham density functional theory (KS-DFT) (7,8), however, with carefully chosen exchange correlation (XC) density functionals can produce smooth potential curves for dissociation with satisfactory accuracy without introducing any unphysical bump and with much smaller computational cost; however, at this time, an XC functional that can be used as a panacea does not exist. In addition to an adequate level of electronic structure...

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Real-time observation of :CF2 formation in the infrared multiple-photon dissociation of fluoroform-d

Cited by 16 publications

References 28 publications

Conversion of CHF3 to CH2CF2 via reaction with CH4 in the presence of CBrF3: An experimental and kinetic modelling study

Conversion of CHF3 to CH2CF2 via reaction with CH4 in the presence of CBrF3: An experimental and kinetic modelling study

Experimental and Modeling Study of the Reaction C₂F₄ (+ M) ⇔ CF₂ + CF₂ (+ M)

Barrierless association of CF ₂ and dissociation of C ₂ F ₄ by variational transition-state theory and system-specific quantum Rice–Ramsperger–Kassel theory

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Real-time observation of :CF2 formation in the infrared multiple-photon dissociation of fluoroform-d

Cited by 16 publications

References 28 publications

Conversion of CHF3 to CH2CF2 via reaction with CH4 in the presence of CBrF3: An experimental and kinetic modelling study

Conversion of CHF3 to CH2CF2 via reaction with CH4 in the presence of CBrF3: An experimental and kinetic modelling study

Experimental and Modeling Study of the Reaction C2F4 (+ M) ⇔ CF2 + CF2 (+ M)

Barrierless association of CF 2 and dissociation of C 2 F 4 by variational transition-state theory and system-specific quantum Rice–Ramsperger–Kassel theory

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Experimental and Modeling Study of the Reaction C₂F₄ (+ M) ⇔ CF₂ + CF₂ (+ M)

Barrierless association of CF ₂ and dissociation of C ₂ F ₄ by variational transition-state theory and system-specific quantum Rice–Ramsperger–Kassel theory