1
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Lang J, Foley CD, Thawoos S, Behzadfar A, Liu Y, Zádor J, Suits AG. Reaction dynamics of S( 3P) with 1,3-butadiene and isoprene: crossed-beam scattering, low-temperature flow experiments, and high-level electronic structure calculations. Faraday Discuss 2024. [PMID: 38807494 DOI: 10.1039/d4fd00009a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Sulfur atoms serve as key players in diverse chemical processes, from astrochemistry at very low temperature to combustion at high temperature. Building upon our prior findings, showing cyclization to thiophenes following the reaction of ground-state sulfur atoms with dienes, we here extend this investigation to include many additional reaction products, guided by detailed theoretical predictions. The outcomes highlight the complex formation of products during intersystem crossing (ISC) to the singlet surfaces. Here, we employed crossed-beam velocity map imaging and high-level ab initio methods to explore the reaction of S(3P) with 1,3-butadiene and isoprene under single-collision conditions and in low-temperature flows. For the butadiene reaction, our experimental results show the formation of thiophene via H2 loss, a 2H-thiophenyl radical through H loss, and thioketene through ethene loss at a slightly higher collision energy compared to previous observations. Complementary Chirped-Pulse Fourier-Transform mmWave spectroscopy (CP-FTmmW) measurements in a uniform flow confirmed the formation of thioketene in the reaction at 20 K. For the isoprene reaction, we observed analogous products along with the 2H-thiophenyl radical arising from methyl loss and C3H4S (loss of ethene or H2 + acetylene). CP-FTmmW detected the formation of thioformaldehyde via loss of 1,3-butadiene, again in the 20 K flow. Coupled-cluster calculations on the pathways found by the automated kinetic workflow code KinBot support these findings and indicate ISC to the singlet surface, leading to the generation of various long-lived intermediates, including 5-membered heterocycles.
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Affiliation(s)
- Jinxin Lang
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Casey D Foley
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Shameemah Thawoos
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Abbas Behzadfar
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Yanan Liu
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Judit Zádor
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA.
| | - Arthur G Suits
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
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2
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Guillaume T, Hays BM, Gupta D, Cooke IR, Abdelkader Khedaoui O, Hearne TS, Drissi M, Sims IR. Product-specific reaction kinetics in continuous uniform supersonic flows probed by chirped-pulse microwave spectroscopy. J Chem Phys 2024; 160:204201. [PMID: 38808747 DOI: 10.1063/5.0203428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 05/06/2024] [Indexed: 05/30/2024] Open
Abstract
Experimental studies of the products of elementary gas-phase chemical reactions occurring at low temperatures (<50 K) are very scarce, but of importance for fundamental studies of reaction dynamics, comparisons with high-level quantum dynamical calculations, and, in particular, for providing data for the modeling of cold astrophysical environments, such as dense interstellar clouds, the atmospheres of the outer planets, and cometary comae. This study describes the construction and testing of a new apparatus designed to measure product branching fractions of elementary bimolecular gas-phase reactions at low temperatures. It combines chirped-pulse Fourier transform millimeter wave spectroscopy with continuous uniform supersonic flows and high repetition rate laser photolysis. After a comprehensive description of the apparatus, the experimental procedures and data processing protocols used for signal recovery, the capabilities of the instrument are explored by the study of the photodissociation of acrylonitrile and the detection of two of its photoproducts, HC3N and HCN. A description is then given of a study of the reactions of the CN radical with C2H2 at 30 K, detecting the HC3N product, and with C2H6 at 10 K, detecting the HCN product. A calibration of these two products is finally attempted using the photodissociation of acrylonitrile as a reference process. The limitations and possible improvements in the instrument are discussed in conclusion.
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Affiliation(s)
| | | | | | | | | | | | | | - Ian R Sims
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
- Institut universitaire de France (IUF), France
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3
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Changala PB, McCarthy MC. Rotational Spectrum of the Phenoxy Radical. J Phys Chem Lett 2024:5063-5069. [PMID: 38701387 DOI: 10.1021/acs.jpclett.4c00962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
We report the hyperfine-resolved rotational spectrum of the gas-phase phenoxy radical in the 8-25 GHz frequency range using cavity Fourier transform microwave spectroscopy. A complete assignment of its complex but well-resolved fine and hyperfine splittings yielded a precisely determined set of rotational constants, spin-rotation parameters, and nuclear hyperfine coupling constants. These results are interpreted with support from high-level quantum chemical calculations to gain detailed insight into the distribution of the unpaired π electron in this prototypical resonance-stabilized radical. The accurate laboratory rest frequencies enable studies of the chemistry of phenoxy in both the laboratory and space. The prospects of extending the present experimental and theoretical techniques to investigate the rotational spectra of isotopic variants and structural isomers of phenoxy and other important gas-phase radical intermediates that are yet undetected at radio wavelengths are discussed.
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Affiliation(s)
- P Bryan Changala
- Center for Astrophysics | Harvard & Smithsonian Cambridge, Massachusetts 02138, United States
| | - Michael C McCarthy
- Center for Astrophysics | Harvard & Smithsonian Cambridge, Massachusetts 02138, United States
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4
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Thawoos S, Suas-David N, Gurusinghe RM, Edlin M, Behzadfar A, Lang J, Suits AG. Low temperature reaction kinetics inside an extended Laval nozzle: REMPI characterization and detection by broadband rotational spectroscopy. J Chem Phys 2023; 159:214201. [PMID: 38054511 DOI: 10.1063/5.0178533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 11/06/2023] [Indexed: 12/07/2023] Open
Abstract
Chirped-Pulse Fourier-Transform millimeter wave (CP-FTmmW) spectroscopy is a powerful method that enables detection of quantum state specific reactants and products in mixtures. We have successfully coupled this technique with a pulsed uniform Laval flow system to study photodissociation and reactions at low temperature, which we refer to as CPUF ("Chirped-Pulse/Uniform flow"). Detection by CPUF requires monitoring the free induction decay (FID) of the rotational coherence. However, the high collision frequency in high-density uniform supersonic flows can interfere with the FID and attenuate the signal. One way to overcome this is to sample the flow, but this can cause interference from shocks in the sampling region. This led us to develop an extended Laval nozzle that creates a uniform flow within the nozzle itself, after which the gas undergoes a shock-free secondary expansion to cold, low pressure conditions ideal for CP-FTmmW detection. Impact pressure measurements, commonly used to characterize Laval flows, cannot be used to monitor the flow within the nozzle. Therefore, we implemented a REMPI (resonance-enhanced multiphoton ionization) detection scheme that allows the interrogation of the conditions of the flow directly inside the extended nozzle, confirming the fluid dynamics simulations of the flow environment. We describe the development of the new 20 K extended flow, along with its characterization using REMPI and computational fluid dynamics. Finally, we demonstrate its application to the first low temperature measurement of the reaction kinetics of HCO with O2 and obtain a rate coefficient at 20 K of 6.66 ± 0.47 × 10-11 cm3 molec-1 s-1.
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Affiliation(s)
- Shameemah Thawoos
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
| | - Nicolas Suas-David
- Univ Rennes, CNRS, Institut de Physique de Rennes - UMR 6251, F-35000 Rennes, France
| | - Ranil M Gurusinghe
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
- Department of Chemistry, Tennessee Tech University, Cookeville, Tennessee 38505, USA
| | - Matthew Edlin
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
| | - Abbas Behzadfar
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
| | - Jinxin Lang
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
| | - Arthur G Suits
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
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5
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Chitarra O, Pirali O, Spaniol JT, Hearne TS, Loison JC, Stanton JF, Martin-Drumel MA. Pure Rotational Spectroscopy of the CH 2CN Radical Extended to the Sub-Millimeter Wave Spectral Region. J Phys Chem A 2022; 126:7502-7513. [PMID: 36198131 DOI: 10.1021/acs.jpca.2c04399] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a thorough pure rotational investigation of the CH2CN radical in its ground vibrational state. Our measurements cover the millimeter and sub-millimeter wave spectral regions (79-860 GHz) using a W-band chirped-pulse instrument and a frequency multiplication chain-based spectrometer. The radical was produced in a flow cell at room temperature by H abstraction from acetonitrile using atomic fluorine. The newly recorded transitions of CH2CN (involving N″ and Ka″ up to 42 and 8, respectively) were combined with the literature data, leading to a refinement of the spectroscopic parameters of the species using a Watson S-reduced Hamiltonian. In particular, the A rotational constant and K-dependent parameters are significantly better determined than in previous studies. The present model, which reproduces all experimental transitions to their experimental accuracy, allows for confident searches for the radical in cold to warm environments of the interstellar medium.
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Affiliation(s)
- Olivia Chitarra
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405Orsay, France
| | - Olivier Pirali
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405Orsay, France
| | - Jean-Thibaut Spaniol
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405Orsay, France
| | - Thomas S Hearne
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405Orsay, France
| | | | - John F Stanton
- Quantum Theory Project, Department of Chemistry, University of Florida, Gainesville32611, Florida, United States
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6
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Hemberger P, Wu X, Pan Z, Bodi A. Continuous Pyrolysis Microreactors: Hot Sources with Little Cooling? New Insights Utilizing Cation Velocity Map Imaging and Threshold Photoelectron Spectroscopy. J Phys Chem A 2022; 126:2196-2210. [PMID: 35316066 DOI: 10.1021/acs.jpca.2c00766] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Resistively heated silicon carbide microreactors are widely applied as continuous sources to selectively prepare elusive and reactive intermediates with astrochemical, catalytic, or combustion relevance to measure their photoelectron spectrum. These reactors also provide deep mechanistic insights into uni- and bimolecular chemistry. However, the sampling conditions and effects have not been fully characterized. We use cation velocity map imaging to measure the velocity distribution of the molecular beam signal and to quantify the scattered, rethermalized background sample. Although translational cooling is efficient in the adiabatic expansion from the reactor, the breakdown diagrams of methane and chlorobenzene confirm that the molecular beam component exhibits a rovibrational temperature comparable with that of the reactor. Thus, rovibrational cooling is practically absent in the expansion from the microreactor. The high rovibrational temperature also affects the threshold photoelectron spectrum of both benzene and the allyl radical in the molecular beam, but to different degrees. While the extreme broadening of the benzene TPES suggests a complex ionization mechanism, the allyl TPES is in fact consistent with an internal temperature close to that of the reactor. The background, room-temperature spectra of both are superbly reproduced by Franck-Condon simulations at 300 K. On the one hand, this leads us to suggest that room-temperature reference spectra should be used in species identification. On the other hand, analysis of the allyl iodide pyrolysis data shows that iodine atoms often recombine to form molecular iodine on the chamber surfaces. Such sampling effects may distort the chemical composition of the scattered background with respect to the molecular beam signal emanating directly from the reactor. This must be considered in quantitative analyses and kinetic modeling.
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Affiliation(s)
- Patrick Hemberger
- Paul Scherrer Insitute, Forschungsstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Xiangkun Wu
- Paul Scherrer Insitute, Forschungsstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Zeyou Pan
- Paul Scherrer Insitute, Forschungsstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Andras Bodi
- Paul Scherrer Insitute, Forschungsstrasse 111, CH-5232 Villigen PSI, Switzerland
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7
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Fulvio D, Potapov A, He J, Henning T. Astrochemical Pathways to Complex Organic and Prebiotic Molecules: Experimental Perspectives for In Situ Solid-State Studies. Life (Basel) 2021; 11:life11060568. [PMID: 34204233 PMCID: PMC8235774 DOI: 10.3390/life11060568] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/11/2021] [Accepted: 06/14/2021] [Indexed: 02/05/2023] Open
Abstract
A deep understanding of the origin of life requires the physical, chemical, and biological study of prebiotic systems and the comprehension of the mechanisms underlying their evolutionary steps. In this context, great attention is paid to the class of interstellar molecules known as "Complex Organic Molecules" (COMs), considered as possible precursors of prebiotic species. Although COMs have already been detected in different astrophysical environments (such as interstellar clouds, protostars, and protoplanetary disks) and in comets, the physical-chemical mechanisms underlying their formation are not yet fully understood. In this framework, a unique contribution comes from laboratory experiments specifically designed to mimic the conditions found in space. We present a review of experimental studies on the formation and evolution of COMs in the solid state, i.e., within ices of astrophysical interest, devoting special attention to the in situ detection and analysis techniques commonly used in laboratory astrochemistry. We discuss their main strengths and weaknesses and provide a perspective view on novel techniques, which may help in overcoming the current experimental challenges.
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Affiliation(s)
- Daniele Fulvio
- Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Naples, Italy
- Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany; (J.H.); (T.H.)
- Correspondence:
| | - Alexey Potapov
- Laboratory Astrophysics Group of the Max Planck Institute for Astronomy at the Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 3, 07743 Jena, Germany;
| | - Jiao He
- Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany; (J.H.); (T.H.)
| | - Thomas Henning
- Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany; (J.H.); (T.H.)
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8
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Mishra P, Fritz SM, Herbers S, Mebel AM, Zwier TS. Gas-phase pyrolysis of trans 3-pentenenitrile: competition between direct and isomerization-mediated dissociation. Phys Chem Chem Phys 2021; 23:6462-6471. [PMID: 33729262 DOI: 10.1039/d1cp00104c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The flash pyrolysis of trans 3-pentenenitrile (3-PN, CH3-CH[double bond, length as m-dash]CH-CH2-CN) was studied by combining the results of VUV photoionization mass spectra with broadband microwave spectra recorded as a function of the temperature of the pyrolysis tube. The two separated functional groups (vinyl and nitrile) open up isomerization as an initial step in competition with unimolecular dissociation. Primary products were detected by keeping the 3-PN concentration low and limiting reaction times to the traversal time of the gas in the pyrolysis tube (∼100 μs). The reaction is quenched and products are cooled by expansion into vacuum before interrogation over the 8-18 GHz region using chirped-pulse broadband methods. 118 nm VUV photoionization of the same reaction mixture provides a means of detecting all products with ionization potentials below 10.5 eV with minimal fragmentation. These results are combined with a detailed computational investigation of the C5H7N and related potential energy surfaces, leading to a consistent picture of the unimolecular decomposition of 3-PN. Loss of two H-atoms to form a 79 amu product is proven from its microwave transitions to contain trans-Z-2,4-pentadienenitrile, while no pyridine is observed. Methyl loss, HCN loss, and breaking the central C(2)-C(3) bond all occur following isomerization of the position of the double bond, thereby opening up low-energy pathways to these decomposition channels.
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Affiliation(s)
- Piyush Mishra
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-1393, USA
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9
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Zaleski DP, Sivaramakrishnan R, Weller HR, Seifert NA, Bross DH, Ruscic B, Moore KB, Elliott SN, Copan AV, Harding LB, Klippenstein SJ, Field RW, Prozument K. Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm. J Am Chem Soc 2021; 143:3124-3142. [PMID: 33615780 DOI: 10.1021/jacs.0c11677] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
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 (CH3C(O)CH3) at a nominal temperature of 1800 K. The major product observed is ketene (CH2CO). Minor products identified include acetaldehyde (CH3CHO), propyne (CH3CCH), propene (CH2CHCH3), 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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Affiliation(s)
- Daniel P Zaleski
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemistry, Colgate University, Hamilton, New York 13346, United States
| | - Raghu Sivaramakrishnan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Hailey R Weller
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Nathan A Seifert
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - David H Bross
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Branko Ruscic
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Kevin B Moore
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Sarah N Elliott
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Andreas V Copan
- Emmanuel College, Natural Sciences Department, Franklin Springs, Georgia 30639, United States
| | - Lawrence B Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kirill Prozument
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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10
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Chesnokov EN, Kubarev VV, Krasnoperov LN, Koshlyakov PV. Magnetic field effect on the free induction decay of hydroxyl radicals (OH) in the terahertz region. Phys Chem Chem Phys 2020; 22:20248-20252. [PMID: 32966402 DOI: 10.1039/d0cp02773a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of an external longitudinal magnetic field on the optical free induction decay from a free radical is observed for the first time. The experiments were performed on a rotational transition of the hydroxyl radical, OH (2Π3/2(J = 1) ← 2Π3/2(J = 0) at 83.8 cm-1), using a terahertz free electron laser. In contrast to the results of the experiments with a stable paramagnetic molecule, NO, the observed effect of an external magnetic field on the free induction decay from hydroxyl radicals is more complicated. A longitudinal magnetic field leads to the rotation of the polarization plane of the FID radiation and to an additional modulation of the signal intensity. The angle of the rotation of the plane of polarization is large, in agreement with the theoretical predictions. The observed FID kinetics in the time domain are in semi-quantitative agreement with the modeling. This observation opens an opportunity for the selective detection of weak signals of short-lived reactive paramagnetic free radicals from overwhelming signals that originate from stable non-paramagnetic species by polarization discrimination.
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Affiliation(s)
- E N Chesnokov
- Voevodsky Institute of Chemical Kinetics and Combustion Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation.
| | - V V Kubarev
- Budker Institute of Nuclear Physics Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation and Novosibirsk State University, Novosibirsk, Russian Federation
| | - L N Krasnoperov
- New Jersey Institute of Technology, Department of Chemistry and Environmental Science, Newark, NJ 07102, USA
| | - P V Koshlyakov
- Voevodsky Institute of Chemical Kinetics and Combustion Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation.
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11
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Zou L, Motiyenko RA, Margulès L, Alekseev EA. Millimeter-wave emission spectrometer based on direct digital synthesis. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:063104. [PMID: 32611015 DOI: 10.1063/5.0004461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 05/31/2020] [Indexed: 06/11/2023]
Abstract
We present a millimeter-wave Fourier transform emission spectrometer whose design is based on the application of a direct digital synthesizer (DDS) up-converted into the Ku-band with subsequent frequency multiplication. The spectrometer covers the frequency range from 50 GHz to 110 GHz and from 150 GHz to 330 GHz. Owing to the fast frequency switching ability of the DDS in the spectrometer, the same radiation source is used both as a generator of short polarizing pulses and as a local oscillator for the heterodyne receiving system. Such a design provides intrinsically coherent reception that allows very long-term data averaging in the time domain, which improves considerably the maximum sensitivity of the spectrometer. The performances of the spectrometer including the data acquisition rate, the sensitivity, and the accuracy of line frequency measurements were tested on the rotational spectra of OCS, NH2CHO, and CH3CH2CN. We show that in the frequency range of 150-300 GHz, the maximum sensitivity of the spectrometer for a 10 min integration time is around 10-9 cm-1 (the minimal value of the absorption coefficient of detectable rotational transition) in the case of narrowband single frequency pulse excitation, and around 10-8 cm-1 in the case of broadband chirped-pulse excitation.
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Affiliation(s)
- Luyao Zou
- Université de Lille, Faculté des Sciences et Technologies, Département Physique, Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, 59655 Villeneuve d'Ascq Cedex, France
| | - Roman A Motiyenko
- Université de Lille, Faculté des Sciences et Technologies, Département Physique, Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, 59655 Villeneuve d'Ascq Cedex, France
| | - Laurent Margulès
- Université de Lille, Faculté des Sciences et Technologies, Département Physique, Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, 59655 Villeneuve d'Ascq Cedex, France
| | - Eugen A Alekseev
- Institute of Radio Astronomy of the National Academy of Sciences of Ukraine (IRA NASU), 4, Mystetstv St., Kharkiv 61002, Ukraine
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12
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Photodissociation transition states characterized by chirped pulse millimeter wave spectroscopy. Proc Natl Acad Sci U S A 2020; 117:146-151. [PMID: 31852828 DOI: 10.1073/pnas.1911326116] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The 193-nm photolysis of CH2CHCN illustrates the capability of chirped-pulse Fourier transform millimeter-wave spectroscopy to characterize transition states. We investigate the HCN, HNC photofragments in highly excited vibrational states using both frequency and intensity information. Measured relative intensities of J = 1-0 rotational transition lines yield vibrational-level population distributions (VPD). These VPDs encode the properties of the parent molecule transition state at which the fragment molecule was born. A Poisson distribution formalism, based on the generalized Franck-Condon principle, is proposed as a framework for extracting information about the transition-state structure from the observed VPD. We employ the isotopologue CH2CDCN to disentangle the unimolecular 3-center DCN elimination mechanism from other pathways to HCN. Our experimental results reveal a previously unknown transition state that we tentatively associate with the HCN eliminated via a secondary, bimolecular reaction.
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13
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Christophe AL, Barnes JT, Twagirayezu S, Mikhonin A, Muckle MT, Neill JL. Direct Measurements of Small Polar Impurities in Gasoline Mixtures Using Molecular Rotational Resonance Spectroscopy. APPLIED SPECTROSCOPY 2019; 73:1334-1339. [PMID: 31219324 DOI: 10.1177/0003702819859012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This paper reports our efforts to determine whether rotational spectroscopy is a useful tool for petroleum analysis. These efforts include the use of a BrightSpec molecular rotational resonance (MRR) spectrometer, which operates in the 260-290 GHz frequency range, to record rotational spectra of small polar contaminants in commercial gasoline. The observed rotational spectra showed rich, but assignable, patterns due to the sensitivity of the MRR to only small polar compounds. Any interference from a complex hydrocarbon matrix, which in conventional chromatographic methods obscures signals from small polar contaminants, is nearly eliminated. In addition to the evident rotational spectrum of ethanol, the spectra of toluene, ethyl cyanide, and acetaldehyde have also been detected. A quantitative method for ethanol has been developed and demonstrated in this paper, whereas the specific analyses of the other polar impurities will be reported in the future. The validity of MRR to be used as an analytical instrument has been examined by constructing a standard linear curve using dilutions of ethanol in water. The linearity and percentage recovery parameters are satisfactory.
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Affiliation(s)
| | - Jalon T Barnes
- Department of Chemistry and Biochemistry, Lamar University, Beaumont, TX, USA
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14
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Rosi M, Skouteris D, Balucani N, Nappi C, Faginas Lago N, Pacifici L, Falcinelli S, Stranges D. An Experimental and Theoretical Investigation of 1-Butanol Pyrolysis. Front Chem 2019; 7:326. [PMID: 31139618 PMCID: PMC6527765 DOI: 10.3389/fchem.2019.00326] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 04/23/2019] [Indexed: 11/17/2022] Open
Abstract
Bioalcohols are a promising family of biofuels. Among them, 1-butanol has a strong potential as a substitute for petrol. In this manuscript, we report on a theoretical and experimental characterization of 1-butanol thermal decomposition, a very important process in the 1-butanol combustion at high temperatures. Advantage has been taken of a flash pyrolysis experimental set-up with mass spectrometric detection, in which the brief residence time of the pyrolyzing mixture inside a short, resistively heated SiC tube allows the identification of the primary products of the decomposing species, limiting secondary processes. Dedicated electronic structure calculations of the relevant potential energy surface have also been performed and RRKM estimates of the rate coefficients and product branching ratios up to 2,000 K are provided. Both electronic structure and RRKM calculations are in line with previous determinations. According to the present study, the H2O elimination channel leading to 1-butene is more important than previously believed. In addition to that, we provide experimental evidence that butanal formation by H2 elimination is not a primary decomposition route. Finally, we have experimental evidence of a small yield of the CH3 elimination channel.
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Affiliation(s)
- Marzio Rosi
- Department of Civil and Environmental Engineering, University of Perugia, Perugia, Italy
| | | | - Nadia Balucani
- Laboratory of Molecular Processes in Combustion, Department of Chemistry, Biology and Biotechnologies, University of Perugia, Perugia, Italy
| | - Caterina Nappi
- Laboratory of Molecular Processes in Combustion, Department of Chemistry, Biology and Biotechnologies, University of Perugia, Perugia, Italy
| | - Noelia Faginas Lago
- Laboratory of Molecular Processes in Combustion, Department of Chemistry, Biology and Biotechnologies, University of Perugia, Perugia, Italy
| | - Leonardo Pacifici
- Master-Up, Perugia, Italy.,Laboratory of Molecular Processes in Combustion, Department of Chemistry, Biology and Biotechnologies, University of Perugia, Perugia, Italy
| | - Stefano Falcinelli
- Department of Civil and Environmental Engineering, University of Perugia, Perugia, Italy
| | - Domenico Stranges
- Department of Chemistry, University of Rome "La Sapienza", Rome, Italy
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15
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Foley CD, Alavi ST, Joalland B, Broderick BM, Dias N, Suits AG. Imaging the infrared multiphoton excitation and dissociation of propargyl chloride. Phys Chem Chem Phys 2019; 21:1528-1535. [PMID: 30617359 DOI: 10.1039/c8cp06668j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Infrared multiphoton excitation is combined with UV excitation and state-resolved probes of Cl(2P3/2), Cl*(2P1/2), and HCl to study the photochemistry of propargyl chloride. The results show evidence both of infrared multiphoton dissociation on the ground electronic state and infrared multiphoton excitation followed by UV dissociation. The results are interpreted with the aid of a full characterization of the stationary points on the ground state using ab initio methods, as well as our recent experimental and theoretical characterization of the UV photochemistry of the molecule. The data suggest elimination of HCl on the ground electronic state produces linear propadienylidene as a coproduct over a roaming-like transition state that accesses the Cl-H-C abstraction geometry. This identification is supported by separate chirped-pulse microwave studies in a quasi-uniform flow also reported here.
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Affiliation(s)
- Casey D Foley
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
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16
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Lauzin C, Schmutz H, Agner JA, Merkt F. Chirped-pulse millimetre-wave spectrometer for the 140–180 GHz region. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1467055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- C. Lauzin
- Institute of condensed Matter and Nanosciences, Université catholique de Louvain, Louvain-la-Neuve, Belgium
- Physical Chemistry Laboratory, ETH Zürich, Zürich, Switzerland
| | - H. Schmutz
- Physical Chemistry Laboratory, ETH Zürich, Zürich, Switzerland
| | - J. A. Agner
- Physical Chemistry Laboratory, ETH Zürich, Zürich, Switzerland
| | - F. Merkt
- Physical Chemistry Laboratory, ETH Zürich, Zürich, Switzerland
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17
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Abeysekera C, Hernandez-Castillo A, Stanton JF, Zwier TS. Broadband Microwave Spectroscopy of 2-Furanyloxy Radical: Primary Pyrolysis Product of the Second-Generation Biofuel 2-Methoxyfuran. J Phys Chem A 2018; 122:6879-6885. [PMID: 30063137 DOI: 10.1021/acs.jpca.8b05102] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chamara Abeysekera
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - A.O. Hernandez-Castillo
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - John F. Stanton
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Timothy S. Zwier
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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18
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Boundary-Layer Model to Predict Chemically Reacting Flow within Heated, High-Speed, Microtubular Reactors. INT J CHEM KINET 2018. [DOI: 10.1002/kin.21173] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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19
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Harrilal CP, DeBlase AF, Fischer JL, Lawler JT, McLuckey SA, Zwier TS. Infrared Population Transfer Spectroscopy of Cryo-Cooled Ions: Quantitative Tests of the Effects of Collisional Cooling on the Room Temperature Conformer Populations. J Phys Chem A 2018; 122:2096-2107. [PMID: 29464953 DOI: 10.1021/acs.jpca.7b12751] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christopher P. Harrilal
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - Andrew F. DeBlase
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - Joshua L. Fischer
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - John T. Lawler
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - Scott A. McLuckey
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - Timothy S. Zwier
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
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20
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Zaleski DP, Harding LB, Klippenstein SJ, Ruscic B, Prozument K. Time-Resolved Kinetic Chirped-Pulse Rotational Spectroscopy in a Room-Temperature Flow Reactor. J Phys Chem Lett 2017; 8:6180-6188. [PMID: 29193976 DOI: 10.1021/acs.jpclett.7b02864] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Chirped-pulse Fourier transform millimeter-wave spectroscopy is a potentially powerful tool for studying chemical reaction dynamics and kinetics. Branching ratios of multiple reaction products and intermediates can be measured with unprecedented chemical specificity; molecular isomers, conformers, and vibrational states have distinct rotational spectra. Here we demonstrate chirped-pulse spectroscopy of vinyl cyanide photoproducts in a flow tube reactor at ambient temperature of 295 K and pressures of 1-10 μbar. This in situ and time-resolved experiment illustrates the utility of this novel approach to investigating chemical reaction dynamics and kinetics. Following 193 nm photodissociation of CH2CHCN, we observe rotational relaxation of energized HCN, HNC, and HCCCN photoproducts with 10 μs time resolution and sample the vibrational population distribution of HCCCN. The experimental branching ratio HCN/HCCCN is compared with a model based on RRKM theory using high-level ab initio calculations, which were in turn validated by comparisons to Active Thermochemical Tables enthalpies.
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Affiliation(s)
- Daniel P Zaleski
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Lawrence B Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Branko Ruscic
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Kirill Prozument
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
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21
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Affiliation(s)
- Curt Wentrup
- School of Chemistry and Molecular Biosciences The University of Queensland Brisbane Qld 4072 Australien
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22
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Wentrup C. Flash Vacuum Pyrolysis: Techniques and Reactions. Angew Chem Int Ed Engl 2017; 56:14808-14835. [PMID: 28675675 DOI: 10.1002/anie.201705118] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Indexed: 12/13/2022]
Abstract
Flash vacuum pyrolysis (FVP) had its beginnings in the 1940s and 1950s, mainly through mass spectrometric detection of pyrolytically formed free radicals. In the 1960s many organic chemists started performing FVP experiments with the purpose of isolating new and interesting compounds and understanding pyrolysis processes. Meanwhile, many different types of apparatus and techniques have been developed, and it is the purpose of this review to present the most important methods as well as a survey of typical reactions and observations that can be achieved with the various techniques. This includes preparative FVP, chemical trapping reactions, matrix isolation, and low temperature spectroscopy of reactive intermediates and unstable molecules, the use of online mass, photoelectron, microwave, and millimeterwave spectroscopies, gas-phase laser pyrolysis, pulsed pyrolysis with supersonic jet expansion, very low pressure pyrolysis for kinetic investigations, solution-spray and falling-solid FVP for involatile compounds, and pyrolysis over solid supports and reagents. Moreover, the combination of FVP with matrix isolation and photochemistry is a powerful tool for investigations of reaction mechanism.
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Affiliation(s)
- Curt Wentrup
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld, 4072, Australia
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23
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Vasiliou AK, Hu H, Cowell TW, Whitman JC, Porterfield J, Parish CA. Modeling Oil Shale Pyrolysis: High-Temperature Unimolecular Decomposition Pathways for Thiophene. J Phys Chem A 2017; 121:7655-7666. [DOI: 10.1021/acs.jpca.7b07582] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- AnGayle K. Vasiliou
- Department
of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, United States
| | - Hui Hu
- Department
of Chemistry, Gottwald Center for the Sciences, University of Richmond, Richmond, Virginia 23713, United States
| | - Thomas W. Cowell
- Department
of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, United States
| | - Jared C. Whitman
- Department
of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, United States
| | - Jessica Porterfield
- Department
of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Carol A. Parish
- Department
of Chemistry, Gottwald Center for the Sciences, University of Richmond, Richmond, Virginia 23713, United States
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24
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Potapov A, Canosa A, Jiménez E, Rowe B. Chemie mit Überschall: 30 Jahre astrochemische Forschung und künftige Herausforderungen. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Alexey Potapov
- Laborastrophysikgruppe des Max-Planck-Instituts für Astronomie am Institut für Festkörperphysik; Friedrich-Schiller-Universität Jena; Helmholtzweg 3 07743 Jena Deutschland
| | - André Canosa
- Département de Physique Moléculaire; Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, Campus de Beaulieu; 263 Avenue du Général Leclerc 35042 Rennes Cedex Frankreich
| | - Elena Jiménez
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas; Universidad de Castilla-La Mancha; Avda. Camilo José Cela, 1B 13071 Ciudad Real Spanien
| | - Bertrand Rowe
- Rowe-consulting, 22 Chemin des Moines; 22750 Saint Jacut de la Mer Frankreich
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25
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Vasiliou AK, Anderson DE, Cowell TW, Kong J, Melhado WF, Phillips MD, Whitman JC. Thermal Decomposition Mechanism for Ethanethiol. J Phys Chem A 2017; 121:4953-4960. [PMID: 28558212 DOI: 10.1021/acs.jpca.7b02629] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The thermal decomposition of ethanethiol was studied using a 1 mm × 2 cm pulsed silicon carbide microtubular reactor, CH3CH2SH + Δ → Products. Unlike previous studies these experiments were able to identify the initial ethanethiol decomposition products. Ethanethiol was entrained in either an Ar or a He carrier gas, passed through a heated (300-1700 K) SiC microtubular reactor (roughly ≤100 μs residence time) and exited into a vacuum chamber. Within one reactor diameter the gas cools to less than 50 K rotationally, and all reactions cease. The resultant molecular beam was probed by photoionization mass spectroscopy and IR spectroscopy. Ethanethiol was found to undergo unimolecular decomposition by three pathways: CH3CH2SH → (1) CH3CH2 + SH, (2) CH3 + H2C═S, and (3) H2C═CH2 + H2S. The experimental findings are in good agreement with electronic structure calculations.
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Affiliation(s)
- AnGayle K Vasiliou
- Department of Chemistry and Biochemistry, Middlebury College , Middlebury, Vermont 05753, United States
| | - Daniel E Anderson
- Department of Chemistry and Biochemistry, Middlebury College , Middlebury, Vermont 05753, United States
| | - Thomas W Cowell
- Department of Chemistry and Biochemistry, Middlebury College , Middlebury, Vermont 05753, United States
| | - Jessica Kong
- Department of Chemistry and Biochemistry, Middlebury College , Middlebury, Vermont 05753, United States
| | - William F Melhado
- Department of Chemistry and Biochemistry, Middlebury College , Middlebury, Vermont 05753, United States
| | - Margaret D Phillips
- Department of Chemistry and Biochemistry, Middlebury College , Middlebury, Vermont 05753, United States
| | - Jared C Whitman
- Department of Chemistry and Biochemistry, Middlebury College , Middlebury, Vermont 05753, United States
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26
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27
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Potapov A, Canosa A, Jiménez E, Rowe B. Uniform Supersonic Chemical Reactors: 30 Years of Astrochemical History and Future Challenges. Angew Chem Int Ed Engl 2017; 56:8618-8640. [DOI: 10.1002/anie.201611240] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/27/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Alexey Potapov
- Laborastrophysikgruppe des Max-Planck-Instituts für Astronomie am Institut für Festkörperphysik; Friedrich-Schiller-Universität Jena; Helmholtzweg 3 07743 Jena Germany
| | - André Canosa
- Département de Physique Moléculaire; Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, Campus de Beaulieu; 263 Avenue du Général Leclerc 35042 Rennes Cedex France
| | - Elena Jiménez
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas; Universidad de Castilla-La Mancha; Avda. Camilo José Cela, 1B 13071 Ciudad Real Spain
| | - Bertrand Rowe
- Rowe-consulting, 22 Chemin des Moines; 22750 Saint Jacut de la Mer France
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28
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Nonlinear two-dimensional terahertz photon echo and rotational spectroscopy in the gas phase. Proc Natl Acad Sci U S A 2016; 113:11800-11805. [PMID: 27702903 DOI: 10.1073/pnas.1609558113] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ultrafast 2D spectroscopy uses correlated multiple light-matter interactions for retrieving dynamic features that may otherwise be hidden under the linear spectrum; its extension to the terahertz regime of the electromagnetic spectrum, where a rich variety of material degrees of freedom reside, remains an experimental challenge. We report a demonstration of ultrafast 2D terahertz spectroscopy of gas-phase molecular rotors at room temperature. Using time-delayed terahertz pulse pairs, we observe photon echoes and other nonlinear signals resulting from molecular dipole orientation induced by multiple terahertz field-dipole interactions. The nonlinear time domain orientation signals are mapped into the frequency domain in 2D rotational spectra that reveal J-state-resolved nonlinear rotational dynamics. The approach enables direct observation of correlated rotational transitions and may reveal rotational coupling and relaxation pathways in the ground electronic and vibrational state.
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29
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Park GB, Field RW. Perspective: The first ten years of broadband chirped pulse Fourier transform microwave spectroscopy. J Chem Phys 2016; 144:200901. [DOI: 10.1063/1.4952762] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- G. Barratt Park
- Institute for Physical Chemistry, University of Göttingen, Tammannstraße 6, 37077 Göttingen, Germany
- Max Planck Institute for Biophysical Chemistry, Göttingen, Am Faßberg 11, 37077 Göttingen, Germany
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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30
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Mullaney JC, Zaleski DP, Tew DP, Walker NR, Legon AC. Geometry of an Isolated Dimer of Imidazole Characterised by Rotational Spectroscopy and Ab Initio Calculations. Chemphyschem 2016; 17:1154-8. [DOI: 10.1002/cphc.201501179] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Indexed: 11/07/2022]
Affiliation(s)
- John C. Mullaney
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne, Tyne and Wear NE1 7RU UK
| | - Daniel P. Zaleski
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne, Tyne and Wear NE1 7RU UK
- Argonne National Laboratory; Chemical Sciences & Engineering; 9700 S. Cass Ave., Bldg. 200 Lemont IL 60439 USA
| | - David P. Tew
- School of Chemistry; University of Bristol; Bristol BS8 1TS UK
| | - Nicholas R. Walker
- School of Chemistry, Bedson Building; Newcastle University; Newcastle upon Tyne, Tyne and Wear NE1 7RU UK
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31
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Shubert VA, Schmitz D, Pérez C, Medcraft C, Krin A, Domingos SR, Patterson D, Schnell M. Chiral Analysis Using Broadband Rotational Spectroscopy. J Phys Chem Lett 2016; 7:341-350. [PMID: 26745342 DOI: 10.1021/acs.jpclett.5b02443] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
broadband microwave spectroscopy is a proven tool to precisely determine molecular properties of gas-phase molecules. Recent developments make it applicable to investigate chiral molecules. Enantiomers can be differentiated, and the enantiomeric excess and, indirectly, the absolute configuration can be determined in a molecule-selective manner. The resonant character and high resolution of rotational spectroscopy provide a unique mixture compatibility. Future directions, such as extending the technique to chemical analysis, are discussed.
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Affiliation(s)
- V Alvin Shubert
- Max-Planck-Institut für Struktur und Dynamik der Materie , Luruper Chaussee 149, D-22761 Hamburg, Germany
- Center for Free-Electron Laser Science , Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - David Schmitz
- Max-Planck-Institut für Struktur und Dynamik der Materie , Luruper Chaussee 149, D-22761 Hamburg, Germany
- Center for Free-Electron Laser Science , Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Cristóbal Pérez
- Max-Planck-Institut für Struktur und Dynamik der Materie , Luruper Chaussee 149, D-22761 Hamburg, Germany
- Center for Free-Electron Laser Science , Luruper Chaussee 149, D-22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg , Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Chris Medcraft
- Max-Planck-Institut für Struktur und Dynamik der Materie , Luruper Chaussee 149, D-22761 Hamburg, Germany
- Center for Free-Electron Laser Science , Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Anna Krin
- Max-Planck-Institut für Struktur und Dynamik der Materie , Luruper Chaussee 149, D-22761 Hamburg, Germany
- Center for Free-Electron Laser Science , Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Sérgio R Domingos
- Max-Planck-Institut für Struktur und Dynamik der Materie , Luruper Chaussee 149, D-22761 Hamburg, Germany
- Center for Free-Electron Laser Science , Luruper Chaussee 149, D-22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg , Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - David Patterson
- Department of Physics, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Melanie Schnell
- Max-Planck-Institut für Struktur und Dynamik der Materie , Luruper Chaussee 149, D-22761 Hamburg, Germany
- Center for Free-Electron Laser Science , Luruper Chaussee 149, D-22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg , Luruper Chaussee 149, D-22761 Hamburg, Germany
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32
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Trevitt AJ, Goulay F. Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection. Phys Chem Chem Phys 2016; 18:5867-82. [DOI: 10.1039/c5cp06389b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gas-phase radical reactions of CN and CH with small hydrocarbons are overviewed with emphasis on isomer-resolved product detection.
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Affiliation(s)
- Adam J. Trevitt
- School of Chemistry
- University of Wollongong
- Wollongong
- Australia
| | - Fabien Goulay
- Department of Chemistry
- West Virginia University
- Morgantown
- USA
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33
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Porterfield JP, Nguyen TL, Baraban JH, Buckingham GT, Troy TP, Kostko O, Ahmed M, Stanton JF, Daily JW, Ellison GB. Isomerization and Fragmentation of Cyclohexanone in a Heated Micro-Reactor. J Phys Chem A 2015; 119:12635-47. [DOI: 10.1021/acs.jpca.5b10984] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jessica P. Porterfield
- Department
of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
| | - Thanh Lam Nguyen
- Department
of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Joshua H. Baraban
- Department
of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
| | - Grant T. Buckingham
- Department
of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
| | - Tyler P. Troy
- Chemical
Sciences Division, Lawrence Berkeley National Laboratories, Berkeley, California 94720, United States
| | - Oleg Kostko
- Chemical
Sciences Division, Lawrence Berkeley National Laboratories, Berkeley, California 94720, United States
| | - Musahid Ahmed
- Chemical
Sciences Division, Lawrence Berkeley National Laboratories, Berkeley, California 94720, United States
| | - John F. Stanton
- Department
of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - John W. Daily
- Center
for Combustion and Environmental Research, Department of Mechanical
Engineering, University of Colorado, Boulder, Colorado 80309-0427, United States
| | - G. Barney Ellison
- Department
of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
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34
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Abeysekera C, Zack LN, Park GB, Joalland B, Oldham JM, Prozument K, Ariyasingha NM, Sims IR, Field RW, Suits AG. A chirped-pulse Fourier-transform microwave/pulsed uniform flow spectrometer. II. Performance and applications for reaction dynamics. J Chem Phys 2015; 141:214203. [PMID: 25481137 DOI: 10.1063/1.4903253] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This second paper in a series of two reports on the performance of a new instrument for studying chemical reaction dynamics and kinetics at low temperatures. Our approach employs chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy to probe photolysis and bimolecular reaction products that are thermalized in pulsed uniform flows. Here we detail the development and testing of a new K(a)-band CP-FTMW spectrometer in combination with the pulsed flow system described in Paper I [J. M. Oldham, C. Abeysekera, B. Joalland, L. N. Zack, K. Prozument, I. R. Sims, G. B. Park, R. W. Field, and A. G. Suits, J. Chem. Phys. 141, 154202 (2014)]. This combination delivers broadband spectra with MHz resolution and allows monitoring, on the μs timescale, of the appearance of transient reaction products. Two benchmark reactive systems are used to illustrate and characterize the performance of this new apparatus: the photodissociation of SO2 at 193 nm, for which the vibrational populations of the SO product are monitored, and the reaction between CN and C2H2, for which the HCCCN product is detected in its vibrational ground state. The results show that the combination of these two well-matched techniques, which we refer to as chirped-pulse in uniform flow, also provides insight into the vibrational and rotational relaxation kinetics of the nascent reaction products. Future directions are discussed, with an emphasis on exploring the low temperature chemistry of complex polyatomic systems.
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Affiliation(s)
- Chamara Abeysekera
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Lindsay N Zack
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - G Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Baptiste Joalland
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - James M Oldham
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Kirill Prozument
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Nuwandi M Ariyasingha
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Ian R Sims
- Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042, Rennes Cedex, France
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Arthur G Suits
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
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Louviot M, Suas-David N, Boudon V, Georges R, Rey M, Kassi S. Strong thermal nonequilibrium in hypersonic CO and CH4 probed by CRDS. J Chem Phys 2015; 142:214305. [DOI: 10.1063/1.4921893] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abeysekera C, Joalland B, Ariyasingha N, Zack LN, Sims IR, Field RW, Suits AG. Product Branching in the Low Temperature Reaction of CN with Propyne by Chirped-Pulse Microwave Spectroscopy in a Uniform Supersonic Flow. J Phys Chem Lett 2015; 6:1599-1604. [PMID: 26263320 DOI: 10.1021/acs.jpclett.5b00519] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A new chirped-pulse/uniform flow (CPUF) spectrometer has been developed and used to determine product branching in a multichannel reaction. With this technique, bimolecular reactions can be initiated in a cold, thermalized, high-density molecular flow and a broadband microwave spectrum acquired for all products with rotational transitions within a chosen frequency window. In this work, the CN + CH3CCH reaction was found to yield HCN via a direct H-abstraction reaction, whereas indirect addition/elimination pathways to HCCCN, CH3CCCN, and CH2CCHCN were also probed. From these observations, quantitative branching ratios were established for all products as 12(5)%, 66(4)%, 22(6)%, and 0(8)% into HCN, HCCCN, CH3CCCN, and CH2CCHCN, respectively. The values are consistent with statistical calculations based on new ab initio results at the CBS-QB3 level of theory. This work is a demonstration of CPUF as a powerful technique for quantitatively determining the branching into polyatomic products from a bimolecular reaction.
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Affiliation(s)
- Chamara Abeysekera
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Baptiste Joalland
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Nuwandi Ariyasingha
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Lindsay N Zack
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Ian R Sims
- ‡Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042, Rennes CEDEX, France
| | - Robert W Field
- §Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Arthur G Suits
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
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Pinto RM, Guerra M, Copeland G, Olariu RI, Rodrigues P, Barros MT, Costa ML, Dias AA. The Mechanism of Pyrolysis of Benzyl Azide: Spectroscopic Evidence for Benzenemethanimine Formation. J Phys Chem A 2015; 119:4118-26. [DOI: 10.1021/acs.jpca.5b02453] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
| | | | - Grant Copeland
- Department of Chemistry, The University of Southampton, Southampton SO17 1BJ, U.K
| | - Romeo I. Olariu
- Faculty
of Chemistry, “Al. I. Cuza” University of Iasi, 11
Carol I, 700506, Iasi, Romania
| | - Paula Rodrigues
- ITQB, Instituto de Tecnologia
Química e Biológica, Universidade Nova de Lisboa, 2780-901 Oeiras, Portugal
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Prozument K, Suleimanov YV, Buesser B, Oldham JM, Green WH, Suits AG, Field RW. A Signature of Roaming Dynamics in the Thermal Decomposition of Ethyl Nitrite: Chirped-Pulse Rotational Spectroscopy and Kinetic Modeling. J Phys Chem Lett 2014; 5:3641-3648. [PMID: 26278732 DOI: 10.1021/jz501758p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Chirped-pulse (CP) Fourier transform rotational spectroscopy is uniquely suited for near-universal quantitative detection and structural characterization of mixtures that contain multiple molecular and radical species. In this work, we employ CP spectroscopy to measure product branching and extract information about the reaction mechanism, guided by kinetic modeling. Pyrolysis of ethyl nitrite, CH3CH2ONO, is studied in a Chen type flash pyrolysis reactor at temperatures of 1000-1800 K. The branching between HNO, CH2O, and CH3CHO products is measured and compared to the kinetic models generated by the Reaction Mechanism Generator software. We find that roaming CH3CH2ONO → CH3CHO + HNO plays an important role in the thermal decomposition of ethyl nitrite, with its rate, at 1000 K, comparable to that of the radical elimination channel CH3CH2ONO → CH3CH2O + NO. HNO is a signature of roaming in this system.
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Affiliation(s)
| | | | - Beat Buesser
- §IBM Research, Smarter Cities Technology Centre, Dublin 15, Ireland
| | - James M Oldham
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | | | - Arthur G Suits
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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Oldham JM, Abeysekera C, Joalland B, Zack LN, Prozument K, Sims IR, Park GB, Field RW, Suits AG. A chirped-pulse Fourier-transform microwave/pulsed uniform flow spectrometer. I. The low-temperature flow system. J Chem Phys 2014; 141:154202. [DOI: 10.1063/1.4897979] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- James M. Oldham
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Chamara Abeysekera
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Baptiste Joalland
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Lindsay N. Zack
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Kirill Prozument
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
| | - Ian R. Sims
- Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042 Rennes Cedex, France
| | - G. Barratt Park
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Arthur G. Suits
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA
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Zaleski DP, Stephens SL, Walker NR. A perspective on chemistry in transient plasma from broadband rotational spectroscopy. Phys Chem Chem Phys 2014; 16:25221-8. [DOI: 10.1039/c4cp04108a] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A review of recent experiments demonstrating the high value of broadband rotational spectroscopy applied to analyse molecular products of plasma chemistry.
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Affiliation(s)
- Daniel P. Zaleski
- School of Chemistry
- Bedson Building
- Newcastle University
- Newcastle upon Tyne
- , UK
| | - Susanna L. Stephens
- School of Chemistry
- Bedson Building
- Newcastle University
- Newcastle upon Tyne
- , UK
| | - Nicholas R. Walker
- School of Chemistry
- Bedson Building
- Newcastle University
- Newcastle upon Tyne
- , UK
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