Strong-Field Ionization of Flash Pyrolysis Reaction Products

Cudry, Fadia; Oldham, James M.; Lingenfelter, Steven; Suits, Arthur G.

doi:10.1021/jp510552a

Cited by 6 publications

(4 citation statements)

References 28 publications

(41 reference statements)

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“…Whether via pyrolysis, ,,,,,− shock wave, ,, or photolysis, − decomposition of acetone has been well studied. It has long been understood that, below about 1100 K, the pyrolysis of acetone proceeds through a free methyl radical mechanism. , Nevertheless, it is instructive to review from a chemical perspective how the pyrolysis of acetone leads to its decomposition into successively smaller species.…”

Section: Resultsmentioning

confidence: 99%

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Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm

et al. 2021

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The development of high-fidelity mechanisms for chemically reactive systems is a challenging process that requires the compilation of rate descriptions for a large and somewhat ill-defined set of reactions. The present unified combination of modeling, experiment, and theory provides a paradigm for improving such mechanism development efforts. Here we combine broadband rotational spectroscopy with detailed chemical modeling based on rate constants obtained from automated ab initio transition state theory-based master equation calculations and high-level thermochemical parametrizations. Broadband rotational spectroscopy offers quantitative and isomer-specific detection by which branching ratios of polar reaction products may be obtained. Using this technique, we observe and characterize products arising from H atom substitution reactions in the flash pyrolysis of acetone (CH 3 C(O)CH 3 ) at a nominal temperature of 1800 K. The major product observed is ketene (CH 2 CO). Minor products identified include acetaldehyde (CH 3 CHO), propyne (CH 3 CCH), propene (CH 2 CHCH 3 ), and water (HDO). Literature mechanisms for the pyrolysis of acetone do not adequately describe the minor products. The inclusion of a variety of substitution reactions, with rate constants and thermochemistry obtained from automated ab initio kinetics predictions and Active Thermochemical Tables analyses, demonstrates an important role for such processes. The pathway to acetaldehyde is shown to be a direct result of substitution of acetone's methyl group by a free H atom, while propene formation arises from OH substitution in the enol form of acetone by a free H atom.

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Section: Resultsmentioning

confidence: 99%

“…Pyrolysis is of both academic − and commercial , interest. Furthermore, mechanisms for pyrolysis are an important subcomponent of combustion mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm

et al. 2021

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“…Near-infrared femtosecond laser pulse can be used to selectively ionize isomers through strong field ionization. 47,48 The laser dependence of the ion signal as well as the fragmentation patterns can be used to identify isomers from complex mixtures. Recent experiments have also demonstrated the ability of chirped-pulse millimeter-wave spectroscopy to identify radicals and closed shell molecules in pyrolysis environments.…”

Section: Introductionmentioning

confidence: 99%

Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection

Trevitt

Goulay

2016

Phys. Chem. Chem. Phys.

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For reactive gas-phase environments, including combustion, extraterrestrials atmospheres and our Earth's atmosphere, the availability of quality chemical data is essential for predictive chemical models. These data include reaction rate coefficients and product branching fractions. This perspective overviews recent isomerresolved production detection experiments for reactions of two of the most reactive gas phase radicals, the CN and CH radicals, with a suite of small hydrocarbons. A particular focus is given to flow-tube experiments using synchrotron photoionization mass spectrometry. Coupled with computational studies and other experiment techniques, flow tube isomer-resolved product detection have provided significant mechanistic details of these radical + neutral reactions with some general patterns emerging. Disciplines Medicine and Health Sciences | Social and Behavioral Sciences ABSTRACTFor reactive gas-phase environments, including combustion, extraterrestrials atmospheres and our Earth's atmosphere, the availability of quality chemical data is essential for predictive chemical models. These data include reaction rate coefficients and product branching fractions. This perspective overviews recent isomer-resolved production detection experiments for reactions of two of the most reactive gas phase radicals, the CN and CH radicals, with a suite of small hydrocarbons. A particular focus is given to flowtube experiments using synchrotron photoionization mass spectrometry. Coupled with computational studies and other experiment techniques, flow tube isomer-resolved product detection have provided significant mechanistic details of these radical + neutral reactions with some general patterns emerging.

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“…The Ar beam is pulsed at 10 Hz with a backing pressure of 5.3 bar into one source chamber via a piezoelectric stack actuator (Physik Instrumente, P212.80) valve 37 with 120 µm poppet translation and 50 µs pulse duration. The vibrationally excited NO is generated with a home-built flash pyrolysis 58 source closely related to the pyrolysis design by Chen and coworkers 59 . The NO beam is introduced into the second source chamber by pulsing a piezoelectric pulsed valve operating at 10 Hz with a backing pressure of 5 bar.…”

Section: Methodsmentioning

confidence: 99%

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

Kamasah¹

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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.

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Strong-Field Ionization of Flash Pyrolysis Reaction Products

Cited by 6 publications

References 28 publications

Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm

Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm

Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection

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

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