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Liu L, Zhang C, Xia Y, Zhang W, Wang Z, Tang X. Dimeric product formation in the self-reaction of small peroxy radicals using synchrotron radiation vacuum ultraviolet photoionization mass spectrometry. CHEMOSPHERE 2024; 363:142846. [PMID: 39025306 DOI: 10.1016/j.chemosphere.2024.142846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 07/11/2024] [Accepted: 07/12/2024] [Indexed: 07/20/2024]
Abstract
Peroxy radicals (RO2) are key reactive intermediates in atmospheric oxidation processes and yet their chemistry is not fully unraveled. Little is known about their structures and the structures of the dimeric products (ROOR) in the self-reaction of small RO2, which are among the most abundant RO2 in the atmosphere. The product branching ratios of ROOR and their atmospheric roles are still in controversy. Here, the self-reaction of propyl peroxy radicals (C3H7O2), a typical small RO2 radical in the atmosphere, has been studied using synchrotron radiation vacuum ultraviolet photoionization mass spectrometry. Both radical (C3H7O) and closed-shell molecular (C3H6O, C3H7OH, C3H7OOC3H7) products in the self-reaction are observed in photoionization mass spectra and their elusive isomers are definitely identified in mass-selected photoionization spectra. Three isomers of the C3H7OOC3H7 dimeric products, R1OOR1, R1OOR2, and R2OOR2 (R1 and R2 represent 1-C3H7 and 2-C3H7, respectively), as well as their complex structures have been determined for the first time. Kinetic experiments are performed and compared with chemical simulations to reveal the sources of specific products. The branching ratio of the C3H7OOC3H7 dimeric channel is measured at 10 ± 5%. This work demonstrates that the dimeric product formation in the self-reaction of small RO2 radicals is non-negligible and should provide valuable new insight into atmospheric modelling.
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Affiliation(s)
- Lingyu Liu
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, Anhui, China; School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei, 230026, Anhui, China
| | - Cuihong Zhang
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, Anhui, China
| | - Yu Xia
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, Anhui, China; Science Island Branch, Graduate School, University of Science and Technology of China, Hefei, 230026, Anhui, China
| | - Weijun Zhang
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, Anhui, China; School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei, 230026, Anhui, China.
| | - Zhandong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, Anhui, China
| | - Xiaofeng Tang
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, Anhui, China.
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2
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Cano Ardila FE, Nagaraju S, Tranter RS, Garcia GA, Desclaux A, Roque Ccacya A, Chaumeix N, Comandini A. External standard calibration method for high-repetition-rate shock tube kinetic studies with synchrotron-based time-of-flight mass spectrometry. Analyst 2024; 149:1586-1596. [PMID: 38289286 PMCID: PMC10895696 DOI: 10.1039/d3an00819c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
The signal levels observed from mass spectrometers coupled by molecular beam sampling to shock tubes are impacted by dynamic pressures in the spectrometer due to rapid pressure changes in the shock tube. Accounting for the impact of the pressure changes is essential if absolute concentrations of species are to be measured. Obtaining such a correction for spectrometers operated with vacuum ultra violet photoionization has been challenging. We present here a new external calibration method which uses VUV-photoionization of CO2 to develop time-dependent corrections to species concentration/time profiles from which kinetic data can be extracted. The experiments were performed with the ICARE-HRRST (high repetition rate shock tube) at the DESIRS beamline of synchrotron SOLEIL. The calibration experiments were performed at temperatures and pressures behind reflected shock waves of 1376 ± 12 K and 6.6 ± 0.1 bar, respectively. Pyrolytic experiments with two aromatic species, toluene (T5 = 1362 ± 22 K, P5 = 6.6 ± 0.2 bar) and ethylbenzene (T5 = 1327 ± 18 K, P5 = 6.7 ± 0.2 bar), are analyzed to test the method. Time dependent concentrations for molecular and radical species were corrected with the new method. The resulting signals were compared with chemical kinetic simulations using a recent mechanism for pyrolytic formation of polycyclic aromatic hydrocarbons. Excellent agreement was obtained between the experimental data and simulations, without adjustment of the model, demonstrating the validity of the external calibration method.
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Affiliation(s)
- Fabian E Cano Ardila
- CNRS-INSIS, I.C.A.R.E., 1C Avenue de la recherche scientifique, 45071 Orléans cedex 2, France.
| | - Sharath Nagaraju
- CNRS-INSIS, I.C.A.R.E., 1C Avenue de la recherche scientifique, 45071 Orléans cedex 2, France.
| | - Robert S Tranter
- Chemical Sciences and Engineering Department, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, USA
| | - Gustavo A Garcia
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin BP 48, 91192 Gif sur Yvette, France
| | - Anthony Desclaux
- CNRS-INSIS, I.C.A.R.E., 1C Avenue de la recherche scientifique, 45071 Orléans cedex 2, France.
| | - Anthony Roque Ccacya
- CNRS-INSIS, I.C.A.R.E., 1C Avenue de la recherche scientifique, 45071 Orléans cedex 2, France.
| | - Nabiha Chaumeix
- CNRS-INSIS, I.C.A.R.E., 1C Avenue de la recherche scientifique, 45071 Orléans cedex 2, France.
| | - Andrea Comandini
- CNRS-INSIS, I.C.A.R.E., 1C Avenue de la recherche scientifique, 45071 Orléans cedex 2, France.
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Singh S, Kawade M, Patwari GN. Dissociative Photoionization of Dimethylpyridines and Trimethylpyridine at 266 nm: Dynamics of Methyl Radical Release. ACS OMEGA 2024; 9:8173-8178. [PMID: 38405504 PMCID: PMC10882603 DOI: 10.1021/acsomega.3c08705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/22/2023] [Accepted: 01/23/2024] [Indexed: 02/27/2024]
Abstract
The 266 nm photolysis of various positional isomers of dimethylpyridines and trimethylpyridine was investigated by measuring the translational energy distribution of the methyl radical following {sp2}C-C{sp3} bond dissociation. The observed translational energy distribution is attributed to the dissociative photoionization in the cationic ground state following [1 + 1 + 1] three-photon absorption. The translational energy distribution profiles of the methyl radical were broad with the maximum translation energy in excess of 2 eV, which originates due to the dissociation of {sp2}C-C{sp3} bond ortho to the N atom in the ring. The dynamics of {sp2}C-C{sp3} bond dissociation in the cationic ground state of methylpyridines is marginally dependent on the number and position of the methyl groups; similar to xylenes, however, it is site-selective with the preferential cleavage of C-C bond in the ortho position to the pyridinic nitrogen atom, which is attributed to the relative stability of the resulting radical cation.
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Affiliation(s)
- Sumitra Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076 , India
| | - Monali Kawade
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076 , India
| | - G Naresh Patwari
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076 , India
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Huang X, Eggart D, Qin G, Sarma BB, Gaur A, Yang J, Pan Y, Li M, Hao J, Yu H, Zimina A, Guo X, Xiao J, Grunwaldt JD, Pan X, Bao X. Methyl radical chemistry in non-oxidative methane activation over metal single sites. Nat Commun 2023; 14:5716. [PMID: 37714864 PMCID: PMC10504359 DOI: 10.1038/s41467-023-41192-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 08/24/2023] [Indexed: 09/17/2023] Open
Abstract
Molybdenum supported on zeolites has been extensively studied as a catalyst for methane dehydroaromatization. Despite significant progress, the actual intermediates and particularly the first C-C bond formation have not yet been elucidated. Herein we report evolution of methyl radicals during non-oxidative methane activation over molybdenum single sites, which leads selectively to value-added chemicals. Operando X-ray absorption spectroscopy and online synchrotron vacuum ultraviolet photoionization mass spectroscopy in combination with electron microscopy and density functional theory calculations reveal the essential role of molybdenum single sites in the generation of methyl radicals and that the formation rate of methyl radicals is linearly correlated with the number of molybdenum single sites. Methyl radicals transform to ethane in the gas phase, which readily dehydrogenates to ethylene in the absence of zeolites. This is essentially similar to the reaction pathway over the previously reported SiO2 lattice-confined single site iron catalyst. However, the availability of a zeolite, either in a physical mixture or as a support, directs the subsequent reaction pathway towards aromatization within the zeolite confined pores, resulting in benzene as the dominant hydrocarbon product. The findings reveal that methyl radical chemistry could be a general feature for metal single site catalysis regardless of the support (either zeolites MCM-22 and ZSM-5 or SiO2) whereas the reaction over aggregated molybdenum carbide nanoparticles likely facilitates carbon deposition through surface C-C coupling. These findings allow furthering the fundamental insights into non-oxidative methane conversion to value-added chemicals.
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Affiliation(s)
- Xin Huang
- State Key Laboratory of Catalysis, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Daniel Eggart
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Karlsruhe, 76131, Germany
| | - Gangqiang Qin
- State Key Laboratory of Catalysis, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Bidyut Bikash Sarma
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, 76344, Germany
| | - Abhijeet Gaur
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Karlsruhe, 76131, Germany
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology, Hefei, 230029, China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology, Hefei, 230029, China
| | - Mingrun Li
- State Key Laboratory of Catalysis, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Jianqi Hao
- State Key Laboratory of Catalysis, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Hongfei Yu
- State Key Laboratory of Catalysis, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Anna Zimina
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, 76344, Germany
| | - Xiaoguang Guo
- State Key Laboratory of Catalysis, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Jianping Xiao
- State Key Laboratory of Catalysis, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Jan-Dierk Grunwaldt
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Karlsruhe, 76131, Germany.
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, 76344, Germany.
| | - Xiulian Pan
- State Key Laboratory of Catalysis, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
| | - Xinhe Bao
- State Key Laboratory of Catalysis, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
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Wang H, Huang M, Chen H, Shan X, Wang Z, Liu F, Sheng L. Experimental and theoretical study on the photoionization of styrene. JOURNAL OF MASS SPECTROMETRY : JMS 2023; 58:e4967. [PMID: 37464983 DOI: 10.1002/jms.4967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 06/27/2023] [Accepted: 07/05/2023] [Indexed: 07/20/2023]
Abstract
This study employed a vacuum ultraviolet synchrotron radiation source and reflectron time-of-flight mass spectrometry (TOF-MS) to investigate the photoionization and dissociation of styrene. By analyzing the photoionization mass spectrum and efficiency curve alongside G3B3 theoretical calculations, we determined the ionization energy of the molecular ion, appearance energy of fragment ions, and relevant dissociation pathways. The major ion peaks observed in the photoionization mass spectra of styrene correspond to C8 H8 + , C8 H7 + and C6 H6 + . The ionization energy of styrene is measured as 8.46 ± 0.03 eV, whereas the appearance energies of C8 H7 + and C6 H6 + are found to be 12.42 ± 0.03 and 12.22 ± 0.03 eV, respectively, in agreement with theoretical values. The main channel for the photodissociation of styrene molecular ions is the formation of benzene ions, whereas the dissociation channel that loses hydrogen atoms is the secondary channel. Based on the experimental results and empirical formulas, the required dissociation energies (Ed ) of C8 H7 + , C8 H6 + and C6 H6 + are calculated to be (3.96 ± 0.06), (4.00 ± 0.06) and (3.76 ± 0.06) eV, respectively. Combined with related thermochemical parameters, the standard enthalpies of formations of C8 H8 + , C8 H7 + , C8 H6 + and C6 H6 + are determined to be 964.2, 1346.3, 1350.2 and 1327.0 kJ/mol, respectively. Based on the theoretical study, the kinetic factors controlling the styrene dissociation reaction process are determined by using the Rice-Ramsperger-Kassel-Marcus (RRKM) theory. This provides a reference for further research on the atmospheric photooxidation reaction mechanism of styrene in atmospheric and interstellar environments.
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Affiliation(s)
- Huanhuan Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, China
| | - Mingqiang Huang
- Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology, College of Chemistry and Chemical Engineering and Environment, Minnan Normal University, Zhangzhou, China
| | - Hao Chen
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, China
| | - Xiaobin Shan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, China
| | - Zhenya Wang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, China
| | - Fuyi Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, China
| | - Liusi Sheng
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, China
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6
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Jin J, Xie C, Gao J, Wang H, Zhang J, Zhao Y, Gao M, Ma J, Wang Z, Guan J. Elucidating the toluene formation mechanism in the reaction of propargyl radical with 1,3-butadiene. Phys Chem Chem Phys 2023; 25:13136-13144. [PMID: 37129089 DOI: 10.1039/d3cp01061a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Toluene is one of the simplest mono-substituted benzene derivatives and an important precursor to form polycyclic aromatic hydrocarbons (PAHs) and soot. However, there is a lack of critical understanding of the formation mechanisms of the toluene molecule. In this work, we explore high-temperature reactions of propargyl radical addition to 1,3-butadiene in a tubular flow microreactor. We obtain experimental evidence for the distinct formations of three C7H8 isomers consisting of toluene, 1,3,5-cycloheptatriene, and 5-methylene-1,3-cyclohexadiene discriminated by synchrotron VUV photoionization efficiency curves. Toluene is identified as the dominant product, which shows strong contrast with the calculated results of the system. By performing theoretical calculations and kinetic simulations, we found that 5-methylene-1,3-cyclohexadiene is a key product of the primary reaction, and toluene formation is enhanced by unavoidable secondary reactions, such as unimolecular isomerization and/or H-assisted isomerization reactions in the SiC microreactor. The current work provides competitive pathways for the enhanced formation of toluene, and may further help disentangle the toluene-promoted molecular growth mechanism of PAHs in combustion environments.
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Affiliation(s)
- Jianhui Jin
- School of Nuclear Science and Engineering, East China University of Technology, Nanchang 330013, P. R. China.
| | - Cheng Xie
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P. R. China.
| | - Jiao Gao
- Dalian Institute of Chemical Physics, Dalian, 116023, P. R. China
| | - Hong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P. R. China.
| | - Jinyang Zhang
- State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Yujie Zhao
- School of Nuclear Science and Engineering, East China University of Technology, Nanchang 330013, P. R. China.
| | - Min Gao
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, P. R. China
| | - Jiabi Ma
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, P. R. China
| | - Zhandong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P. R. China.
- State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Jiwen Guan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P. R. China.
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7
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Selby TM, Goulay F, Soorkia S, Ray A, Jasper AW, Klippenstein SJ, Morozov AN, Mebel AM, Savee JD, Taatjes CA, Osborn DL. Radical-Radical Reactions in Molecular Weight Growth: The Phenyl + Propargyl Reaction. J Phys Chem A 2023; 127:2577-2590. [PMID: 36905386 DOI: 10.1021/acs.jpca.2c08121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
The mechanism for hydrocarbon ring growth in sooting environments is still the subject of considerable debate. The reaction of phenyl radical (C6H5) with propargyl radical (H2CCCH) provides an important prototype for radical-radical ring-growth pathways. We studied this reaction experimentally over the temperature range of 300-1000 K and pressure range of 4-10 Torr using time-resolved multiplexed photoionization mass spectrometry. We detect both the C9H8 and C9H7 + H product channels and report experimental isomer-resolved product branching fractions for the C9H8 product. We compare these experiments to theoretical kinetics predictions from a recently published study augmented by new calculations. These ab initio transition state theory-based master equation calculations employ high-quality potential energy surfaces, conventional transition state theory for the tight transition states, and direct CASPT2-based variable reaction coordinate transition state theory (VRC-TST) for the barrierless channels. At 300 K only the direct adducts from radical-radical addition are observed, with good agreement between experimental and theoretical branching fractions, supporting the VRC-TST calculations of the barrierless entrance channel. As the temperature is increased to 1000 K we observe two additional isomers, including indene, a two-ring polycyclic aromatic hydrocarbon, and a small amount of bimolecular products C9H7 + H. Our calculated branching fractions for the phenyl + propargyl reaction predict significantly less indene than observed experimentally. We present further calculations and experimental evidence that the most likely cause of this discrepancy is the contribution of H atom reactions, both H + indenyl (C9H7) recombination to indene and H-assisted isomerization that converts less stable C9H8 isomers into indene. Especially at low pressures typical of laboratory investigations, H-atom-assisted isomerization needs to be considered. Regardless, the experimental observation of indene demonstrates that the title reaction leads, either directly or indirectly, to the formation of the second ring in polycyclic aromatic hydrocarbons.
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Affiliation(s)
- Talitha M Selby
- Department of Mathematics and Natural Sciences, University of Wisconsin-Milwaukee, West Bend, Wisconsin 53095, United States
| | - Fabien Goulay
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Satchin Soorkia
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, F-91405 Orsay, France
| | - Amelia Ray
- Department of Chemistry, University of Wisconsin-Parkside, Kenosha, Wisconsin 53144, United States
| | - Ahren W Jasper
- 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
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - John D Savee
- KLA Corporation, Milpitas, California 95035, United States
| | - Craig A Taatjes
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551, United States
| | - David L Osborn
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551, United States
- Department of Chemical Engineering, University of California, Davis, Davis, California 95616, United States
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8
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Liu B, Dong S, Debleza J, Chen W, Xu Q, Wang H, Bourgalais J, Herbinet O, Curran HJ, Battin-Leclerc F, Wang Z. Experimental and Updated Kinetic Modeling Study of Neopentane Low Temperature Oxidation. J Phys Chem A 2023; 127:2113-2122. [PMID: 36815799 DOI: 10.1021/acs.jpca.2c03795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Neopentane is an ideal fuel model to study low-temperature oxidation chemistry. The significant discrepancies between experimental data and simulations using the existing neopentane models indicate that an updated study of neopentane oxidation is needed. In this work, neopentane oxidation experiments are carried out using two jet-stirred reactors (JSRs) at 1 atm, at a residence time of 3 s, and at three different equivalence ratios of 0.5, 0.9, and 1.62. Two different analytical methods (synchrotron vacuum ultraviolet photoionization mass spectrometry and gas chromatography) were used to investigate the species distributions. Numerous oxidation intermediates were detected and quantified, including acetone, 3,3-dimethyloxetane, methacrolein, isobutene, 2-methylpropanal, isobutyric acid, and peroxides, which are valuable for validating the kinetic model describing neopentane oxidation. In the model development, the pressure dependencies of the rate constants for the reaction classes Q̇OOH + O2 and Q̇OOH decompositions are considered. This addition improves the prediction of the low-temperature oxidation reactivity of neopentane. Another focus of model development is to improve the prediction of carboxylic acids formed during the low-temperature oxidation of neopentane. The detection and identification of isobutyric acid indicates the existence of the Korcek mechanism during neopentane oxidation. Regarding the formation of acetic acid, the reaction channels are considered to be initiated from the reactions of ȮH radical addition to acetaldehyde/acetone. This updated kinetic model is validated extensively against the experimental data in this work and various experimental data available in the literature, including ignition delay times (IDTs) from both shock tubes (STs) and rapid compression machines (RCMs) and JSR speciation data at high temperatures.
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Affiliation(s)
- Bingzhi Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, PR China
| | - Shijun Dong
- Combustion Chemistry Centre, School of Biological and Chemical Sciences, Ryan Institute, MaREI, University of Galway, Galway H91 TK33, Ireland.,School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China
| | - Janney Debleza
- LRGP, Université de Lorraine and CNRS, F-54000 Nancy, France
| | - Weiye Chen
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, PR China
| | - Qiang Xu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, PR China
| | - Hong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, PR China
| | | | | | - Henry J Curran
- Combustion Chemistry Centre, School of Biological and Chemical Sciences, Ryan Institute, MaREI, University of Galway, Galway H91 TK33, Ireland
| | | | - Zhandong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, PR China.,State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, PR China
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9
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Wu X, Pan Z, Steglich M, Ascher P, Bodi A, Bjelić S, Hemberger P. A direct liquid sampling interface for photoelectron photoion coincidence spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:034103. [PMID: 37012765 DOI: 10.1063/5.0136665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 02/19/2023] [Indexed: 06/19/2023]
Abstract
We introduce an effective and flexible high vacuum interface to probe the liquid phase with photoelectron photoion coincidence (liq-PEPICO) spectroscopy at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source. The interface comprises a high-temperature sheath gas-driven vaporizer, which initially produces aerosols. The particles evaporate and form a molecular beam, which is skimmed and ionized by VUV radiation. The molecular beam is characterized using ion velocity map imaging, and the vaporization parameters of the liq-PEPICO source have been optimized to improve the detection sensitivity. Time-of-flight mass spectra and photoion mass-selected threshold photoelectron spectra (ms-TPES) were recorded for an ethanolic solution of 4-propylguaiacol, vanillin, and 4-hydroxybenzaldehyde (1 g/l of each). The ground state ms-TPES band of vanillin reproduces the reference, room-temperature spectrum well. The ms-TPES for 4-propylguaiacol and 4-hydroxybenzaldehyde are reported for the first time. Vertical ionization energies obtained by equation-of-motion calculations reproduce the photoelectron spectral features. We also investigated the aldol condensation dynamics of benzaldehyde with acetone using liq-PEPICO. Our direct sampling approach, thus, enables probing reactions at ambient pressure during classical synthesis procedures and microfluidic chip devices.
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Affiliation(s)
- Xiangkun Wu
- Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Zeyou Pan
- Paul Scherrer Institute, 5232 Villigen, Switzerland
| | | | | | - Andras Bodi
- Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Saša Bjelić
- Paul Scherrer Institute, 5232 Villigen, Switzerland
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10
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Liutkova A, Zhang H, Simons JFM, Mezari B, Mirolo M, Garcia GA, Hensen EJM, Kosinov N. Ca Cations Impact the Local Environment inside HZSM-5 Pores during the Methanol-to-Hydrocarbons Reaction. ACS Catal 2023; 13:3471-3484. [PMID: 36970466 PMCID: PMC10028611 DOI: 10.1021/acscatal.3c00059] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/10/2023] [Indexed: 02/25/2023]
Abstract
The methanol-to-hydrocarbons (MTH) process is an industrially relevant method to produce valuable light olefins such as propylene. One of the ways to enhance propylene selectivity is to modify zeolite catalysts with alkaline earth cations. The underlying mechanistic aspects of this type of promotion are not well understood. Here, we study the interaction of Ca2+ with reaction intermediates and products formed during the MTH reaction. Using transient kinetic and spectroscopic tools, we find strong indications that the selectivity differences between Ca/ZSM-5 and HZSM-5 are related to the different local environment inside the pores due to the presence of Ca2+. In particular, Ca/ZSM-5 strongly retains water, hydrocarbons, and oxygenates, which occupy as much as 10% of the micropores during the ongoing MTH reaction. This change in the effective pore geometry affects the formation of hydrocarbon pool components and in this way directs the MTH reaction toward the olefin cycle.
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Affiliation(s)
- Anna Liutkova
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Hao Zhang
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Jérôme F. M. Simons
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Brahim Mezari
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Marta Mirolo
- ESRF, The European Synchrotron, 71 Avenue des Martyrs, CS40220, 38043 Grenoble, Cedex 9, France
| | - Gustavo A. Garcia
- Synchrotron SOLEIL, L’Orme des Merisiers, St Aubin, B.P. 48, 91192 Gif sur Yvette, France
| | - Emiel J. M. Hensen
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Nikolay Kosinov
- Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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11
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Banyon C, Tranter RS. High-Temperature Dissociation of Neopentanol: Shock Tube/Photoionization Mass Spectrometry Studies. J Phys Chem A 2023; 127:1293-1301. [PMID: 36716350 DOI: 10.1021/acs.jpca.2c07358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The pyrolysis mechanism of 2,2-dimethylpropan-1-ol (neopentanol) has been investigated at high temperatures (1128-1401K) and high pressures (5 and 15 bar). The experiments were performed in a miniature shock tube coupled to a time-of-flight mass spectrometer. Cations were generated by tunable vacuum ultraviolet photoionization resulting in multidimensional data sets containing mass and photoionization spectra and the time histories of species. At the elevated temperatures and pressures of this work, neopentanol was determined to dissociate primarily by the scission of a C-C bond yielding tert-butyl and hydroxymethyl radicals. These promptly form isobutene and formaldehyde by H-atom elimination. In the structurally similar molecule neopentane, roaming radical reactions have previously been found to be important under conditions close to the present work (1260-1459 K, 1.1 bar). There are two possible roaming radical reactions for neopentanol. However, no experimental evidence for these reactions was found at the elevated pressures in this study, and the dissociation of neopentanol is dominated by bond scission yielding radical products.
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Affiliation(s)
- Colin Banyon
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois60439, United States
| | - Robert S Tranter
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois60439, United States
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12
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Zhuang H, Chen L, Xu Q, Liu B, Liu P, Wang Z, Jia L. Measurement and summary of photoionization data for biomass-derived compounds. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2022; 36:e9412. [PMID: 36195998 DOI: 10.1002/rcm.9412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/30/2022] [Accepted: 10/01/2022] [Indexed: 06/16/2023]
Abstract
RATIONALE Biomass is a potential feedstock for making liquid fuels and valuable chemicals. Quantitative analysis of biomass conversion in real time by photoionization mass spectrometry (PIMS) is an important way to understand the reaction process. However, the lack of photoionization data for biomass-derived compounds limits the research using PIMS. METHODS Measurements of photoionization data were performed with synchrotron vacuum ultraviolet PIMS. Toluene and methanol were used as calibrated references and solvents in this experiment since their photoionization cross-sections (PICS) are well documented in the literature. RESULTS The ionization energies (IEs) of 23 biomass-derived compounds were measured. Among them, the PICSs of 14 compounds were calibrated and presented. Besides, the IEs of 95 other biomass-derived compounds and their typical fragment ions were also summarized. CONCLUSIONS A photoionization database related to IEs and PICSs of biomass-derived compounds (m/z < 200) is established. PICSs of most biomass-derived compounds have low values at the most frequently used photoionization energy of 10.5 eV. Lignin-derived compounds have lower IEs than carbohydrate-derived compounds.
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Affiliation(s)
- Haifeng Zhuang
- School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei, Anhui, China
| | - Lin Chen
- School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei, Anhui, China
| | - Qiang Xu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, China
| | - Bingzhi Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, China
| | - Peiqi Liu
- School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei, Anhui, China
| | - Zhandong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, China
- State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui, China
| | - Liangyuan Jia
- School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei, Anhui, China
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13
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Reaction Mechanisms of Toluene Decomposition in Non-Thermal Plasma: How does It Compare with Benzene? FUNDAMENTAL RESEARCH 2022. [DOI: 10.1016/j.fmre.2022.03.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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14
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Bejoy NB, Kawade M, Singh S, Patwari GN. Dynamics of Methyl Radical Formation Following 266 nm Dissociative Photoionization of Xylenes and Mesitylene. J Phys Chem A 2022; 126:1960-1965. [PMID: 35294201 DOI: 10.1021/acs.jpca.1c10885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 266 nm dissociative photoionization of three xylene isomers and mesitylene leading to the formation of methyl radical was examined. The total translational energy distribution profiles [P(ET)] for the methyl radical were almost identical for all of the three isomers of xylene and mesitylene, while a substantial difference was observed for the corresponding P(ET) profile of the co-fragment produced by loss of one methyl group in m-xylene. This observation is attributed to the formation of the methyl radical from alternate channels induced by the probe. The P(ET) profiles were rationalized based on the dissociation of {sp2}C-C{sp3} bond in the cationic state, wherein the {sp2}C-C{sp3} bond dissociation energy is substantially lower relative to the neutral ground state. The dissociation in the cationic state follows a resonant three-photon absorption process, resulting in a maximum translational energy of about 1.6-1.8 eV for the photofragments in the center-of-mass frame. Fitting of the P(ET) profiles to empirical function reveals that the dynamics of {sp2}C-C{sp3} bond dissociation is insensitive to the position of substitution but marginally dependent on the number of methyl groups.
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Affiliation(s)
- Namitha Brijit Bejoy
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Monali Kawade
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sumitra Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - G Naresh Patwari
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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15
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Wu L, Qi K, Xu M, Liu C, Pan Y. Effects of dopants in the imaging of mouse brain by desorption electrospray ionization/post-photoionization mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2022; 57:e4813. [PMID: 35189674 DOI: 10.1002/jms.4813] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 12/08/2021] [Accepted: 12/16/2021] [Indexed: 06/14/2023]
Abstract
Desorption electrospray ionization/post-photoionization (DESI/PI) is a newly developed ionization method by the combination of DESI and post-photoionization for the simultaneous imaging of polar and nonpolar compounds in biological tissues. Dopants are of great importance in DESI/PI for the enhancement of signal intensities through ion-molecule reactions. In this work, to evaluate the performance of dopants in DESI/PI, an efficient homogenate model was developed, and four kinds of dopants (toluene, chlorobenzene, bromobenzene, and anisole) were tested using homogenate of mouse brain tissue as target sample. The influences of the dopants on the signal enhancements of different compounds were explained reasonably by the ionization mechanism. Then, the dopants with their optimum volume contents were applied to the mass spectrometry imaging (MSI). For a comprehensive imaging of various compounds with different polarities, methanol/toluene/formic acid (7:3:0.1) was chosen as the best choice. Finally, the stronger quantitative ability of DESI/PI with toluene as dopant for a few compounds in mouse brain tissue was demonstrated.
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Affiliation(s)
- Liutian Wu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Keke Qi
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Minggao Xu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Chengyuan Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
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16
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Zhou Z, Yang J, Yuan W, Wang Z, Pan Y, Qi F. Probing combustion and catalysis intermediates by synchrotron vacuum ultraviolet photoionization molecular-beam mass spectrometry: recent progress and future opportunities. Phys Chem Chem Phys 2022; 24:21567-21577. [DOI: 10.1039/d2cp02899a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Soft photoionization molecular-beam mass spectrometry (PI MBMS) with synchrotron vacuum ultraviolet light (SVUV) has has a significant development and broad applications in recent decades. Particularly, the tunability of SVUV enables...
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17
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18
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Sikes T, Banyon C, Schwind RA, Lynch PT, Comandini A, Sivaramakrishnan R, Tranter RS. Initiation reactions in the high temperature decomposition of styrene. Phys Chem Chem Phys 2021; 23:18432-18448. [PMID: 34612384 PMCID: PMC8409502 DOI: 10.1039/d1cp02437j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The thermal decomposition of styrene was investigated in a combined experimental, theory and modeling study with particular emphasis placed on the initial dissociation reactions. Two sets of shock tube/time-of-flight mass spectrometry (TOF-MS) experiments were performed to identify reaction products and their order of appearance. One set of experiments was conducted with a miniature high repetition rate shock tube at the Advanced Light Source at Lawrence Berkeley National Laboratory using synchrotron vacuum ultraviolet photoionization. The other set of experiments was performed in a diaphragmless shock tube (DFST) using electron impact ionization. The datasets span 1660–2260 K and 0.5–12 atm. The results show a marked transition from aromatic products at low temperatures to polyacetylenes, up to C8H2, at high temperatures. The TOF-MS experiments were complemented by DFST/LS (laser schlieren densitometry) experiments covering 1800–2250 K and 60–240 Torr. These were particularly sensitive to the initial dissociation reactions. These reactions were investigated theoretically and revealed the dissociation of styrene to be a complex multichannel process with strong pressure and temperature dependencies that were evaluated with multi-well master equation simulations. Simulations of the LS data with a mechanism developed in this work are in excellent agreement with the experimental data. From these simulations, rate coefficients for the dissociation of styrene were obtained that are in good agreement with the theoretical predictions. The simulation results also provide fair predictions of the temperature and pressure dependencies of the products observed in the TOF-MS studies. Prior experimental studies of styrene pyrolysis concluded that the main products were benzene and acetylene. In contrast, this study finds that the majority of styrene dissociates to create five styryl radical isomers. Of these, α-styryl accounts for about 50% with the other isomers consuming approximately 20%. It was also found that C–C bond scission to phenyl and vinyl radicals consumes up to 25% of styrene. Finally the dissociation of styrene to benzene and vinylidene accounts for roughly 5% of styrene consumption. Comments are made on the apparent differences between the results of this work and prior literature. A combined theoretical and experimental study showing styrene primarily decomposes to styryl radicals + H.![]()
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Affiliation(s)
- Travis Sikes
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Ave., Lemont, IL 60439, USA.
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19
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Yang J, Smith MC, Prendergast MB, Chu TC, Green WH. C 14H 10 polycyclic aromatic hydrocarbon formation by acetylene addition to naphthalenyl radicals observed. Phys Chem Chem Phys 2021; 23:14325-14339. [PMID: 34165136 DOI: 10.1039/d1cp01565f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation of polycyclic aromatic hydrocarbons (PAHs) during combustion has a substantial impact on environmental pollution and public health. The hydrogen-abstraction-acetylene-addition (HACA) mechanism is expected to be a significant source of larger PAHs containing more than two rings. In this study, the reactions of 1-naphthalenyl and 2-naphthalenyl radicals with acetylene (C2H2) are investigated using VUV photoionization time-of-flight mass spectrometry at 500 to 800 K, 15 to 50 torr, and reaction times up to 10 ms. Our experimental conditions allow us to probe the Bittner-Howard and modified Frenklach HACA routes, but not routes that require multiple radicals to drive the chemistry. The kinetic measurements are compared to a temperature-dependent kinetic model constructed using quantum chemistry calculations and accounting for chemical-activation and fall-off effects. We measure significant quantities of C14H10 (likely phenanthrene and anthracene), as well as 2-ethynylnaphthalene (C12H8), from the reaction of the 2-naphthalenyl radical with C2H2; these results are consistent with the predictions of the kinetic model and the HACA mechanism, but contradict a previous experimental study that indicated no C14H10 formation in the 2-naphthalenyl + C2H2 reaction. In the 1-naphthalenyl radical + C2H2 reaction system, the primary product measured is C12H8, consistent with the predicted formation of acenaphthylene via HACA. The present work provides direct experimental evidence that single-radical HACA can be an important mechanism for the formation of PAHs larger than naphthalene, validating a common assumption in combustion models.
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Affiliation(s)
- Jeehyun Yang
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Mica C Smith
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Matthew B Prendergast
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Te-Chun Chu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - William H Green
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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20
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Huang J, Huang C, Wu X, Hou Q, Tian G, Yang J, Zhang F. Combined experimental and theoretical study on photoionization cross sections of benzonitrile and o/m/p-cyanotoluene. J Chem Phys 2021; 154:244301. [PMID: 34241365 DOI: 10.1063/5.0053119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Photoionization cross sections (PICSs) for the products of the reaction from CN with toluene, including benzonitrile and o/m/p-cyanotoluene, were obtained at photon energies ranging from ionization thresholds to 14 eV by tunable synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Theoretical calculations based on the frozen-core Hartree-Fock approximation and Franck-Condon simulations were carried out to cross-verify the measured PICS. The results show that the photoionization cross sections of benzonitrile and cyanotoluene isomers are similar. The generalized charge decomposition analysis was used to investigate the components of the highest occupied molecular orbital (HOMO) and HOMO-1. It was found that the HOMO and HOMO-1 of benzonitrile and cyanotoluene isomers are dominated by the features of the benzene ring, indicating that the substitution of CN and methyl has a minor influence on the PICS of the studied molecules. The reported PICS on benzonitrile and cyanotoluene isomers in the present work could contribute to the near-threshold PIMS experiments and determine the ionization and dissociation rates in interstellar space for these crucial species. The theoretical analysis on characteristics of molecular orbitals provides clues to estimating the PICS of similar substituted aromatic compounds.
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Affiliation(s)
- Jiabin Huang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Can Huang
- Chair of Technical Thermodynamics, RWTH Aachen University, 52062 Aachen, Germany
| | - Xiaoqing Wu
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Qifeng Hou
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Guangjun Tian
- Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, People's Republic of China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Feng Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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21
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Yuan W, Zhao L, Yang J, Zhou Z, Li Y, Qi F. Insights into the Decomposition and Oxidation Chemistry of p-Xylene in Laminar Premixed Flames. J Phys Chem A 2021; 125:3189-3197. [PMID: 33829792 DOI: 10.1021/acs.jpca.1c00745] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This work reports an experimental and kinetic modeling investigation on laminar premixed flame of p-xylene at 0.04 atm and equivalence ratios of 0.75, 1.0, and 1.79. Intermediates such as the p-xylyl radical, p-xylylene, and styrene, as well as polycyclic aromatic hydrocarbons (PAHs), were detected by using synchrotron vacuum ultraviolet photoionization mass spectrometry. Based on our previous aromatic kinetic model, a detailed kinetic model of p-xylene combustion was developed, and the model was validated against the present flame structure data. Model analysis work was also performed in order to reveal the important reactions in p-xylene decomposition and oxidation. The H-abstraction reactions leading to the p-xylyl radical are found to control the consumption of p-xylene in all the three flames. In the rich flame, p-xylyl mainly suffers the H-elimination and isomerization reactions, which produce p-xylylene and the o-xylyl radical, respectively. The further decomposition reactions of the o-xylyl radical contribute to the production of styrene, which is another important C8 intermediate observed in the rich flame. In the stoichiometric and lean flames, p-xylyl mainly suffers the oxidation reactions by O, which give p-methylbenzaldehyde as major product. The growth pathways of PAHs in the rich flame were also investigated in this work. Indenyl, indene, naphthalene, and phenanthrene were observed as the abundantly produced bicyclic and tricyclic PAHs due to the existence of direct formation pathways from the decomposition of p-xylyl radical.
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Affiliation(s)
- Wenhao Yuan
- Key Laboratory for Power Machinery and Engineering of MOE, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Long Zhao
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Zhongyue Zhou
- Key Laboratory for Power Machinery and Engineering of MOE, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Yuyang Li
- Key Laboratory for Power Machinery and Engineering of MOE, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Fei Qi
- Key Laboratory for Power Machinery and Engineering of MOE, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
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22
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Hu Y, Liu C, Xu Y, Yang J, Pan Y. Identification of Isobars and Isomers in Cigarette Sidestream Smoke in Real Time by Synchrotron Radiation Photoionization Mass Spectrometry and Multiple Linear Regression. Anal Chem 2021; 93:5718-5726. [PMID: 33797228 DOI: 10.1021/acs.analchem.0c04781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Direct analysis of chemical components in fresh cigarette smoke in real time is a challenging task. In this work, by using a novel continuous cigarette-pushing and smoke-introducing setup combined with synchrotron radiation photoionization mass spectrometry (SR-PIMS), the photoionization mass spectra of fresh gaseous cigarette sidestream smoke (SSS) from the combustion of solid tobacco could be recorded in real time, and the photoionization efficiency (PIE) curves of each mass peak could be obtained for the first time. Hence, lots of well-known chemical components and even isomers could be identified by their discriminated onsets or PIE curve simulation. Moreover, diimine, 2H-azirine, and sulfur monoxide, which have never been reported in cigarette smoke, were observed in cigarette SSS, and even two intermediates, ethenol and propen-2-ol, anticipated to exist were actually observed and distinguished. To increase the qualification accuracy, a new simulation method based on multiple linear regression (MLR) was developed and applied for the PIE curve simulation, where qualification mistakes caused by subjective judgements could be eliminated as far as possible.
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Affiliation(s)
- Yonghua Hu
- Center of Technology, China Tobacco Anhui Industrial Co, Ltd, Hefei, Anhui 230088, P. R. China
| | - Chengyuan Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Yingbo Xu
- Center of Technology, China Tobacco Anhui Industrial Co, Ltd, Hefei, Anhui 230088, P. R. China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
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23
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Xu M, Zhu B, Zhao L, Sun Y, Pan Y, Yang J. Atmospheric-Pressure Pyrolysis Study of Chlorobenzene Using Synchrotron Radiation Photoionization Mass Spectrometry. J Phys Chem A 2021; 125:1949-1957. [PMID: 33651613 DOI: 10.1021/acs.jpca.0c10413] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pyrolysis of chlorobenzene (C6H5Cl) at 760 Torr was studied in the temperature range of 873-1223 K. The pyrolysis products including intermediates and chlorinated aromatics were detected and quantified via synchrotron radiation photoionization mass spectrometry. Furthermore, the photoionization cross sections of chlorobenzene were experimentally measured. On the basis of the experimental results, the decomposition pathways of chlorobenzene were discussed as well as the generation and consumption pathways of the main products. Benzene is the main product of chlorobenzene pyrolysis. Chlorobiphenyl (C12H9Cl), dichlorobiphenyl (C12H8Cl2), and chlorotriphenylene (C18H11Cl) predominated in trace chlorinated aromatic products. Chlorobenzene decomposed initially to form two radicals [chlorophenyl (·C6H4Cl) and phenyl (·C6H5)] and the important intermediate o-benzyne (o-C6H4). The propagation processes of chlorinated aromatics, including polychlorinated naphthalenes and polychlorinated biphenyls, were mainly triggered by chlorobenzene, chlorophenyl, and benzene via the even-numbered-carbon growth mechanism. Besides, the small-molecule products such as acetylene (C2H2), 1,3,5-hexatriyne (C6H2), and diacetylene (C4H2) were formed via the bond cleavage of o-benzyne (o-C6H4).
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Affiliation(s)
- Minggao Xu
- School of Metallurgical Engineering, Anhui University of Technology, Maanshan 243002, People's Republic of China.,National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, People's Republic of China
| | - Baozhong Zhu
- School of Metallurgical Engineering, Anhui University of Technology, Maanshan 243002, People's Republic of China.,National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, People's Republic of China
| | - Long Zhao
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, People's Republic of China
| | - Yunlan Sun
- School of Metallurgical Engineering, Anhui University of Technology, Maanshan 243002, People's Republic of China.,School of Petroleum Engineering, Changzhou University, Changzhou 213164, Jiangsu, People's Republic of China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, People's Republic of China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, People's Republic of China
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24
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Elucidating the differences in oxidation of high-performance α- and β- diisobutylene biofuels via Synchrotron photoionization mass spectrometry. Sci Rep 2020; 10:21776. [PMID: 33311537 PMCID: PMC7733457 DOI: 10.1038/s41598-020-76462-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 10/21/2020] [Indexed: 11/09/2022] Open
Abstract
Biofuels are a promising ecologically viable and renewable alternative to petroleum fuels, with the potential to reduce net greenhouse gas emissions. However, biomass sourced fuels are often produced as blends of hydrocarbons and their oxygenates. Such blending complicates the implementation of these fuels in combustion applications. Variations in a biofuel's composition will dictate combustion properties such as auto ignition temperature, reaction delay time, and reaction pathways. A handful of novel drop-in replacement biofuels for conventional transportation fuels have recently been down selected from a list of over 10,000 potential candidates as part of the U.S. Department of Energy's (DOE) Co-Optimization of Fuels and Engines (Co-Optima) initiative. Diisobutylene (DIB) is one such high-performing hydrocarbon which can readily be produced from the dehydration and dimerization of isobutanol, produced from the fermentation of biomass-derived sugars. The two most common isomers realized, from this process, are 2,4,4-trimethyl-1-pentene (α-DIB) and 2,4,4-trimethyl-2-pentene (β-DIB). Due to a difference in olefinic bond location, the α- and β- isomer exhibit dramatically different ignition temperatures at constant pressure and equivalence ratio. This may be attributed to different fragmentation pathways enabled by allylic versus vinylic carbons. For optimal implementation of these biofuel candidates, explicit identification of the intermediates formed during the combustion of each of the isomers is needed. To investigate the combustion pathways of these molecules, tunable vacuum ultraviolet (VUV) light (in the range 8.1-11.0 eV) available at the Lawrence Berkeley National Laboratory's Advanced Light Source (ALS) has been used in conjunction with a jet stirred reactor (JSR) and time-of-flight mass spectrometry to probe intermediates formed. Relative intensity curves for intermediate mass fragments produced during this process were obtained. Several important unique intermediates were identified at the lowest observable combustion temperature with static pressure of 93,325 Pa and for 1.5 s residence time. As this relatively short residence time is just after ignition, this study is targeted at the fuels' ignition events. Ignition characteristics for both isomers were found to be strongly dependent on the kinetics of C4 and C7 fragment production and decomposition, with the tert-butyl radical as a key intermediate species. However, the ignition of α-DIB exhibited larger concentrations of C4 compounds over C7, while the reverse was true for β-DIB. These identified species will allow for enhanced engineering modeling of fuel blending and engine design.
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Jin H, Yang J, Farooq A. Determination of absolute photoionization cross-sections of some aromatic hydrocarbons. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8899. [PMID: 32677075 DOI: 10.1002/rcm.8899] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 06/11/2023]
Abstract
RATIONALE Aromatic hydrocarbons play an important role in the formation and growth of polycyclic aromatic hydrocarbon (PAH) and soot particles. Measurements of their absolute photoionization cross-sections (PICSs), that benefit the quantitative investigation of mass spectrometry, are still lacking, however. METHODS PICSs of some aromatic hydrocarbons were measured with tunable synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Nitric oxide and benzene were chosen as standard references for PICS calibration, since their photoionization cross-sections are well documented in the literature. Binary liquid mixtures of the investigated molecules and their specific solvents were used in the measurements. RESULTS The investigated aromatics include naphthalene, phenanthrene, 1-methylnaphthalene, indene, 2-/3-/4-methylphenylacetylene, 2-methylindene, diphenylacetylene, 1-/2-ethynylnaphthalene and acenaphthylene. Photo-induced fragments from the molecules were also observed with increasing photon energy. CONCLUSIONS Based on our measurements and literature data, PICSs of most aromatic molecules have very similar values beyond their ionization energies. However, molecules that contain the phenylacetylene structure have PICSs higher than other aromatics.
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Affiliation(s)
- Hanfeng Jin
- Physical Sciences and Engineering Division, Clean Combustion Research Centre, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, China
| | - Aamir Farooq
- Physical Sciences and Engineering Division, Clean Combustion Research Centre, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
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Wen Z, Tang X, Fittschen C, Zhang C, Wang T, Wang C, Gu X, Zhang W. Online analysis of gas-phase radical reactions using vacuum ultraviolet lamp photoionization and time-of-flight mass spectrometry. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:043201. [PMID: 32357716 DOI: 10.1063/1.5135387] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 03/26/2020] [Indexed: 06/11/2023]
Abstract
A home-made vacuum ultraviolet photoionization time-of-flight mass spectrometer has been developed and coupled to an atmospheric simulation chamber operated at atmospheric pressure and to a fast flow tube at low pressure (1-10 Torr). Gas sampling from the simulation chamber is realized directly via a capillary effusive beam, and sampling from the flow tube is via a continuous molecular beam inlet. Both devices are connected simultaneously to the ionization chamber of the mass spectrometer and can be switched in-between within minutes to study gas-phase radical reactions of atmospheric interest in a large range of reaction conditions and reaction times (from milliseconds in the flow tube to hours in the simulation chamber). A cage-shaped photoionization source combined with a commercial 10.6 eV krypton lamp has been developed to provide a high ion collection efficiency along the long light path in the cage. This way, a multiplexed detection with high sensitivity down to the sub-parts per billion volume concentration range, e.g., a limit of detection of 0.3 ppbv with an accumulation time of 60 s for benzene and 1.3 ppbv for the methyl radical, is obtained. The performance and suitability of the setup are illustrated by the study of the chlorine-initiated oxidation reaction of toluene in the atmospheric simulation chamber and in the fast flow tube. Stable products and reactive intermediates have been well-determined and their reaction dynamics are discussed.
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Affiliation(s)
- Zuoying Wen
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Xiaofeng Tang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Christa Fittschen
- University Lille, CNRS, UMR 8522, PC2A - Physicochimie des Processus de Combustion et de l'Atmosphère, F-59000 Lille, France
| | - Cuihong Zhang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Tao Wang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Chengcheng Wang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Xuejun Gu
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Weijun Zhang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
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Hoener M, Kaczmarek D, Bierkandt T, Bodi A, Hemberger P, Kasper T. A pressurized flow reactor combustion experiment interfaced with synchrotron double imaging photoelectron photoion coincidence spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:045115. [PMID: 32357689 DOI: 10.1063/1.5141168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 03/29/2020] [Indexed: 06/11/2023]
Abstract
A new pressurized low-temperature combustion experiment has been commissioned at the Swiss Light Source, Paul Scherrer Institute. The experiment uses photoionization with tunable synchrotron radiation and double imaging photoelectron photoion coincidence (i2PEPICO) detection at the vacuum ultraviolet beamline. The experimental setup is described, including the high-pressure reactor experiment, sampling interface, and reactant delivery system. The CRF-PEPICO (Combustion Reactions Followed by Photoelectron Photoion Coincidence) endstation and VUV beamline are briefly elaborated. The novel aspects of the apparatus and the new components are elucidated in detail, such as the fluid supply system to the reactor and the reactor integration into the endstation. We also present a system overview of the experimental setup. The technical details are followed by a description of the experimental procedure used to operate the pressurized flow reactor setup. Finally, first experimental results demonstrating the capability of the setup are provided and analyzed. A major advantage of this new experiment is that the excellent isomer resolution capabilities of the i2PEPICO technique can be transferred to the investigation of reactions at elevated pressures of several bars. This enables the investigation of pressure effects on the reactivity of fuel mixtures and covers more realistic conditions found in technical combustors. The capability to obtain quantitative oxidation data is confirmed, and the main and certain intermediate species are quantified for a selected condition. The results show excellent agreement with a chemical kinetics model and previously published reference measurements performed with a gas chromatography setup.
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Affiliation(s)
- M Hoener
- Mass Spectrometry in Reactive Flows - Institute for Combustion and Gas Dynamics (IVG), University Duisburg-Essen, Duisburg 47057, Germany
| | - D Kaczmarek
- Mass Spectrometry in Reactive Flows - Institute for Combustion and Gas Dynamics (IVG), University Duisburg-Essen, Duisburg 47057, Germany
| | - T Bierkandt
- German Aerospace Center (DLR) - Institute of Combustion Technology, Stuttgart 70569, Germany
| | - A Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry - Paul Scherrer Institute, Villigen 5232, Switzerland
| | - P Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry - Paul Scherrer Institute, Villigen 5232, Switzerland
| | - T Kasper
- Mass Spectrometry in Reactive Flows - Institute for Combustion and Gas Dynamics (IVG), University Duisburg-Essen, Duisburg 47057, Germany
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Chu TC, Buras ZJ, Eyob B, Smith MC, Liu M, Green WH. Direct Kinetics and Product Measurement of Phenyl Radical + Ethylene. J Phys Chem A 2020; 124:2352-2365. [PMID: 32118435 PMCID: PMC7307927 DOI: 10.1021/acs.jpca.9b11543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
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The phenyl + ethylene (C6H5 + C2H4) reaction network was
explored experimentally and theoretically
to understand the temperature dependence of the reaction kinetics
and product distribution under various temperature and pressure conditions.
The flash photolysis apparatus combining laser absorbance spectroscopy
(LAS) and time-resolved molecular beam mass spectrometry (MBMS) was
used to study reactions on the C8H9 potential
energy surface (PES). In LAS experiments, 505.3 nm laser light selectively
probed C6H5 decay, and we measured the total
C6H5 consumption rate coefficients in the intermediate
temperature region (400–800 K), which connects previous experiments
performed in high-temperature (pyrolysis) and low-temperature (cavity-ring-down
methods) regions. From the quantum chemistry calculations by Tokmakov
and Lin using the G2M(RCC5)//B3LYP method, we constructed a kinetic
model and estimated phenomenological pressure-dependent rate coefficients, k(T, P), with the Arkane
package in the reaction mechanism generator. The MBMS experiments,
performed at 600–800 K and 10–50 Torr, revealed three
major product peaks: m/z = 105 (adducts,
mostly 2-phenylethyl radical, but also 1-phenylethyl radical, ortho-ethyl phenyl radical, and a spiro-fused ring radical),
104 (styrene, co-product with a H atom), and 78 (benzene, co-product
with C2H3 radical). Product branching ratios
were predicted by the model and validated by experiments for the first
time. At 600 K and 10 Torr, the yield ratio of the H-abstraction reaction
(forming benzene + C2H3) is measured to be 1.1%
and the H-loss channel (styrene + H) has a 2.5% yield ratio. The model
predicts 1.0% for H-abstraction and 2.3% for H-loss, which is within
the experimental error bars. The branching ratio and formation of
styrene increase at high temperature due to the favored formally direct
channel (1.0% at 600 K and 10 Torr, 5.8% at 800 K and 10 Torr in the
model prediction) and the faster β-scission reactions of C8H9 isomers. The importance of pressure dependence
in kinetics is verified by the increase in the yield of the stabilized
adduct from radical addition from 80.2% (800 K, 10 Torr) to 88.9%
(800 K, 50 Torr), at the expense of styrene + H. The pressure-dependent
model developed in this work is well validated by the LAS and MBMS
measurements and gives a complete picture of the C6H5 + C2H4 reaction.
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Affiliation(s)
- Te-Chun Chu
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Zachary J Buras
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Brook Eyob
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Mica C Smith
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Mengjie Liu
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - William H Green
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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29
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Bourgalais J, Gouid Z, Herbinet O, Garcia GA, Arnoux P, Wang Z, Tran LS, Vanhove G, Hochlaf M, Nahon L, Battin-Leclerc F. Isomer-sensitive characterization of low temperature oxidation reaction products by coupling a jet-stirred reactor to an electron/ion coincidence spectrometer: case of n-pentane. Phys Chem Chem Phys 2020; 22:1222-1241. [DOI: 10.1039/c9cp04992d] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using a tunable vacuum ultraviolet synchrotron beam line and first principle computations, a jet-stirred reactor was coupled for the first time to a photoionization mass spectrometer using electron/ion coincidence imaging.
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Affiliation(s)
- Jérémy Bourgalais
- LATMOS/IPSL
- UVSQ Université Paris-Saclay
- Sorbonne Université
- CNRS
- Guyancourt
| | - Zied Gouid
- Université Gustave Eiffel
- COSYS/LISIS
- Champs sur Marne
- France
| | - Olivier Herbinet
- CNRS
- Université de Lorraine
- Laboratoire Réactions et Génie des Procédés
- UPR 3349
- Nancy F-54000
| | - Gustavo A. Garcia
- Synchrotron SOLEIL
- L’Orme des Merisiers
- 91192 Gif-sur-Yvette Cedex
- France
| | | | - Zhandong Wang
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- People's Republic of China
| | - Luc-Sy Tran
- Physicochimie des Processus de Combustion et de l’Atmosphère (PC2A)
- UMR 8522 CNRS
- Université de Lille
- F-59000 Lille
- France
| | - Guillaume Vanhove
- Physicochimie des Processus de Combustion et de l’Atmosphère (PC2A)
- UMR 8522 CNRS
- Université de Lille
- F-59000 Lille
- France
| | - Majdi Hochlaf
- Université Gustave Eiffel
- COSYS/LISIS
- Champs sur Marne
- France
| | - Laurent Nahon
- Synchrotron SOLEIL
- L’Orme des Merisiers
- 91192 Gif-sur-Yvette Cedex
- France
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30
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Abplanalp MJ, Frigge R, Kaiser RI. Low-temperature synthesis of polycyclic aromatic hydrocarbons in Titan's surface ices and on airless bodies. SCIENCE ADVANCES 2019; 5:eaaw5841. [PMID: 31663015 PMCID: PMC6795510 DOI: 10.1126/sciadv.aaw5841] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 09/22/2019] [Indexed: 06/10/2023]
Abstract
Titan's equatorial dunes represent the most monumental surface structures in our Solar System, but the chemical composition of their dark organics remains a fundamental, unsolved enigma, with solid acetylene detected near the dunes implicated as a key feedstock. Here, we reveal in laboratory simulation experiments that aromatics such as benzene, naphthalene, and phenanthrene-prospective building blocks of the organic dune material-can be efficiently synthesized via galactic cosmic ray exposure of low-temperature acetylene ices on Titan's surface, hence challenging conventional wisdom that aromatic hydrocarbons are formed solely in Titan's atmosphere. These processes are also of critical importance in unraveling the origin and chemical composition of the dark surfaces of airless bodies in the outer Solar System, where hydrocarbon precipitation from the atmosphere cannot occur. This finding notably advances our understanding of the distribution of carbon throughout our Solar System such as on Kuiper belt objects like Makemake.
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Affiliation(s)
- Matthew J. Abplanalp
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Robert Frigge
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Ralf I. Kaiser
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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31
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Chu TC, Buras ZJ, Smith MC, Uwagwu AB, Green WH. From benzene to naphthalene: direct measurement of reactions and intermediates of phenyl radicals and acetylene. Phys Chem Chem Phys 2019; 21:22248-22258. [DOI: 10.1039/c9cp04554f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
First-time measurement of time evolution of the main products and critical intermediates on phenyl HACA pathways with a validated pressure-dependent model.
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Affiliation(s)
- Te-Chun Chu
- Massachusetts Institute of Technology
- Cambridge
- USA
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32
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Prendergast MB, Kirk BB, Savee JD, Osborn DL, Taatjes CA, Hemberger P, Blanksby SJ, da Silva G, Trevitt AJ. Product detection study of the gas-phase oxidation of methylphenyl radicals using synchrotron photoionisation mass spectrometry. Phys Chem Chem Phys 2019; 21:17939-17949. [DOI: 10.1039/c9cp01935a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reactions of ortho and meta-methylphenyl radicals with oxygen form products that depend acutely on the position of the methyl group.
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Affiliation(s)
| | | | - John D. Savee
- Combustion Research Facility
- Sandia National Laboratories
- Livermore
- USA
| | - David L. Osborn
- Combustion Research Facility
- Sandia National Laboratories
- Livermore
- USA
| | - Craig A. Taatjes
- Combustion Research Facility
- Sandia National Laboratories
- Livermore
- USA
| | - Patrick Hemberger
- Laboratory for Femtochemistry and Synchrotron Radiation
- Paul Scherrer Institut
- CH-5232 Villigen PSI
- Switzerland
| | - Stephen J. Blanksby
- Central Analytical Research Facility
- Queensland University of Technology
- Brisbane QLD 4001
- Australia
| | - Gabriel da Silva
- Department of Chemical Engineering
- The University of Melbourne
- Melbourne
- Australia
| | - Adam J. Trevitt
- School of Chemistry
- University of Wollongong
- Wollongong
- Australia
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33
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Otten A, Wooten M, Medrano A, Fathi Y, Meloni G. Investigation of Oxidation Reaction Products of 2-Phenylethanol Using Synchrotron Photoionization. J Phys Chem A 2018; 122:6789-6798. [PMID: 30044638 DOI: 10.1021/acs.jpca.8b03985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A photolytically Cl-initiated oxidation reaction of 2-phenylethanol (2PE) was carried out at the Advanced Light Source (ALS) in the Lawrence Berkeley National Laboratory. Using the multiplex photoionization mass spectrometer, coupled with the tunable vacuum ultraviolet radiation of the ALS, data were collected at low pressure (4-6 Torr) and temperature (298-550 K) regimes. Data analysis was performed via characterization of the reaction species photoionization spectra and kinetic traces. Products and reaction pathways are also computed using the CBS-QB3 composite method. The present results suggest primary products m/ z = 30 (formaldehyde), 106 (benzaldehyde), and 120 (phenylacetaldehyde) at 298 K, and m/ z = 120 (phenylacetaldehyde) at 550 K. Branching fractions at room temperature are 27 ± 6.5% for formaldehyde, 24 ± 4.5% for benzaldehyde, and 25 ± 5.8% for phenylacetaldehyde and 60 ± 14% for phenylacetaldehyde at 550 K.
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Affiliation(s)
- Adam Otten
- Department of Chemistry , University of San Francisco , San Francisco , California 94117 , United States
| | - Magaly Wooten
- Department of Chemistry , University of San Francisco , San Francisco , California 94117 , United States
| | - Anthony Medrano
- Department of Chemistry , University of San Francisco , San Francisco , California 94117 , United States
| | - Yasmin Fathi
- Department of Chemistry , University of San Francisco , San Francisco , California 94117 , United States
| | - Giovanni Meloni
- Department of Physical and Chemical Sciences , University of L'Aquila , L'Aquila 67100 , Italy
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Middaugh JE, Buras ZJ, Matrat M, Chu TC, Kim YS, Alecu IM, Vasiliou AK, Goldsmith CF, Green WH. A combined photoionization time-of-flight mass spectrometry and laser absorption spectrometry flash photolysis apparatus for simultaneous determination of reaction rates and product branching. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:074102. [PMID: 30068092 DOI: 10.1063/1.5024399] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 07/04/2018] [Indexed: 06/08/2023]
Abstract
In recent years, predictions of product branching for reactions of consequence to both combustion and atmospheric chemistry have outpaced validating experiments. An apparatus is described that aims to fill this void by combining several well-known experimental techniques into one: flash photolysis for radical generation, multiple-pass laser absorption spectrometry (LAS) for overall kinetics measurements, and time-resolved photoionization time-of-flight mass spectrometry (PI TOF-MS) for product branching quantification. The sensitivity of both the LAS and PI TOF-MS detection techniques is shown to be suitable for experiments with initial photolytically generated radical concentrations of ∼1 × 1012 molecules cm-3. As it is fast (μs time resolution) and non-intrusive, LAS is preferred for accurate kinetics (time-dependence) measurements. By contrast, PI TOF-MS is preferred for product quantification because it provides a near-complete picture of the reactor composition in a single mass spectrum. The value of simultaneous LAS and PI TOF-MS detection is demonstrated for the chemically interesting phenyl radical + propene system.
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Affiliation(s)
- Joshua E Middaugh
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Zachary J Buras
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Mickael Matrat
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Te-Chun Chu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Young-Seok Kim
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Ionut M Alecu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - AnGayle K Vasiliou
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - C Franklin Goldsmith
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - William H Green
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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35
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A Combined Experimental and Theoretical Study on the Formation of Interstellar Propylene Oxide (CH3CHCH2O)—A Chiral Molecule. ACTA ACUST UNITED AC 2018. [DOI: 10.3847/1538-4357/aac383] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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36
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Zhang M, Guo H, Zhang L. Roaming-Mediated CH 2NH Elimination from the Ionization of Aromatic Ethylamines. ChemistryOpen 2017; 6:40-45. [PMID: 28168149 PMCID: PMC5288767 DOI: 10.1002/open.201600144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 12/12/2016] [Indexed: 12/02/2022] Open
Abstract
The ionization of aromatic ethylamines by photons or electrons leads to elimination of CH2NH fragments, supposedly deriving from the McLafferty rearrangement involving intramolecular γ‐hydrogen transfer. Using tryptamine and phenethylamine as examples, the results reported here suggest that the McLafferty mechanism is inadequate for interpreting the observations of CH2NH elimination due to much higher calculated appearance energy than experimentally measured values. Furthermore, by considering the roaming‐mediated effect, the calculated appearance energy for the elimination of CH2NH fragments is reduced and matches well with the experimental results and verifies the existence of roaming‐mediated effect. This effect could potentially be extended to explain the general CH2NH elimination of aromatic ethylamines. Due to the similar hydrogen transfer to that of the McLafferty mechanism, the roaming‐mediated effect was taken into account to suggest a novel mechanism, termed the “roaming‐modified McLafferty rearrangement”, that explains the observations of CH2NH elimination in the ionization of aromatic ethylamines. This is a reasonable modification of the McLafferty rearrangement mechanism.
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Affiliation(s)
- Mengxing Zhang
- National Synchrotron Radiation Laboratory; University of Science and Technology of China; Hefei Anhui 230029 P.R. China
| | - Huijun Guo
- Vacree Technologies Co., Ltd; Hefei Anhui 230088 P.R. China
- University of Science and Technology of China; Hefei Anhui 230029 P.R. China
| | - Lidong Zhang
- National Synchrotron Radiation Laboratory; University of Science and Technology of China; Hefei Anhui 230029 P.R. China
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37
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Benham K, Hodyss R, Fernández FM, Orlando TM. Laser-Induced Acoustic Desorption Atmospheric Pressure Photoionization via VUV-Generating Microplasmas. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1805-1812. [PMID: 27624160 DOI: 10.1007/s13361-016-1467-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Revised: 07/27/2016] [Accepted: 07/28/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate the first application of laser-induced acoustic desorption (LIAD) and atmospheric pressure photoionization (APPI) as a mass spectrometric method for detecting low-polarity organics. This was accomplished using a Lyman-α (10.2 eV) photon generating microhollow cathode discharge (MHCD) microplasma photon source in conjunction with the addition of a gas-phase molecular dopant. This combination provided a soft desorption and a relatively soft ionization technique. Selected compounds analyzed include α-tocopherol, perylene, cholesterol, phenanthrene, phylloquinone, and squalene. Detectable surface concentrations as low as a few pmol per spot sampled were achievable using test molecules. The combination of LIAD and APPI provided a soft desorption and ionization technique that can allow detection of labile, low-polarity, structurally complex molecules over a wide mass range with minimal fragmentation. Graphical Abstract ᅟ.
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Affiliation(s)
- Kevin Benham
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA, 30332, USA
| | - Robert Hodyss
- Cryogenic Chemistry Laboratory, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
| | - Facundo M Fernández
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA, 30332, USA
| | - Thomas M Orlando
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA, 30332, USA.
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA, 30332, USA.
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Zhou Z, Du X, Yang J, Wang Y, Li C, Wei S, Du L, Li Y, Qi F, Wang Q. The vacuum ultraviolet beamline/endstations at NSRL dedicated to combustion research. JOURNAL OF SYNCHROTRON RADIATION 2016; 23:1035-45. [PMID: 27359154 DOI: 10.1107/s1600577516005816] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/07/2016] [Indexed: 05/21/2023]
Abstract
An undulator-based vacuum ultraviolet (VUV) beamline (BL03U), intended for combustion chemistry studies, has been constructed at the National Synchrotron Radiation Laboratory (NSRL) in Hefei, China. The beamline is connected to the newly upgraded Hefei Light Source (HLS II), and could deliver photons in the 5-21 eV range, with a photon flux of 10(13) photons s(-1) at 10 eV when the beam current is 300 mA. The monochromator of the beamline is equipped with two gratings (200 lines mm(-1) and 400 lines mm(-1)) and its resolving power is 3900 at 7.3 eV for the 200 lines mm(-1) grating and 4200 at 14.6 eV for the 400 lines mm(-1) grating. The beamline serves three endstations which are designed for respective studies of premixed flame, fuel pyrolysis in flow reactor, and oxidation in jet-stirred reactor. Each endstation contains a reactor chamber, an ionization chamber where the molecular beam intersects with the VUV light, and a home-made reflectron time-of-flight mass spectrometer. The performance of the beamline and endstations with some preliminary results is presented here. The ability to detect reactive intermediates (e.g. H, O, OH and hydroperoxides) is advantageous in combustion chemistry research.
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Affiliation(s)
- Zhongyue Zhou
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Xuewei Du
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Yizun Wang
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Chaoyang Li
- China Academy of Engineering Physics, Mianyang, Sichuan 621900, People's Republic of China
| | - Shen Wei
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Liangliang Du
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
| | - Yuyang Li
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Fei Qi
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Qiuping Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, People's Republic of China
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Herbinet O, Rodriguez A, Husson B, Battin-Leclerc F, Wang Z, Cheng Z, Qi F. Study of the Formation of the First Aromatic Rings in the Pyrolysis of Cyclopentene. J Phys Chem A 2016; 120:668-82. [DOI: 10.1021/acs.jpca.5b09203] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Olivier Herbinet
- Laboratoire
Réactions et Génie des Procédés, Université de Lorraine, UMR 7274, BP 20451, 1 rue Grandville, Nancy, F-54000, France
- Laboratoire
Réactions et Génie des Procédés, CNRS, UMR 7274, BP 20451, 1 rue Grandville, Nancy, F-54000, France
| | - Anne Rodriguez
- Laboratoire
Réactions et Génie des Procédés, Université de Lorraine, UMR 7274, BP 20451, 1 rue Grandville, Nancy, F-54000, France
- Laboratoire
Réactions et Génie des Procédés, CNRS, UMR 7274, BP 20451, 1 rue Grandville, Nancy, F-54000, France
| | - Benoit Husson
- Laboratoire
Réactions et Génie des Procédés, Université de Lorraine, UMR 7274, BP 20451, 1 rue Grandville, Nancy, F-54000, France
- Laboratoire
Réactions et Génie des Procédés, CNRS, UMR 7274, BP 20451, 1 rue Grandville, Nancy, F-54000, France
| | - Frédérique Battin-Leclerc
- Laboratoire
Réactions et Génie des Procédés, Université de Lorraine, UMR 7274, BP 20451, 1 rue Grandville, Nancy, F-54000, France
- Laboratoire
Réactions et Génie des Procédés, CNRS, UMR 7274, BP 20451, 1 rue Grandville, Nancy, F-54000, France
| | - Zhandong Wang
- National
Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Zhanjun Cheng
- National
Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
| | - Fei Qi
- National
Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
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Smith AR, Meloni G. Absolute photoionization cross sections of furanic fuels: 2-ethylfuran, 2-acetylfuran and furfural. JOURNAL OF MASS SPECTROMETRY : JMS 2015; 50:1206-1213. [PMID: 26505765 DOI: 10.1002/jms.3638] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 07/23/2015] [Accepted: 07/28/2015] [Indexed: 06/05/2023]
Abstract
Absolute photoionization cross sections of the molecules 2-ethylfuran, 2-acetylfuran and furfural, including partial ionization cross sections for the dissociative ionized fragments, are measured for the first time. These measurements are important because they allow fuel quantification via photoionization mass spectrometry and the development of quantitative kinetic modeling for the complex combustion of potential fuels. The experiments are carried out using synchrotron photoionization mass spectrometry with an orthogonal time-of-flight spectrometer used for mass analysis at the Advanced Light Source of Lawrence Berkeley National Laboratory. The CBS-QB3 calculations of adiabatic ionization energies and appearance energies agree well with the experimental results. Several bond dissociation energies are also derived and presented.
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Affiliation(s)
- Audrey R Smith
- Department of Chemistry, University of San Francisco, San Francisco, CA, 94117-1080, USA
| | - Giovanni Meloni
- Department of Chemistry, University of San Francisco, San Francisco, CA, 94117-1080, USA
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Liu Y, Gerber T, Radi P, Knopp G. Ultrafast imaging of electronic relaxation in n-propylbenzene: Direct observation of intermediate state. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 149:54-58. [PMID: 25942085 DOI: 10.1016/j.saa.2015.04.050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 04/13/2015] [Accepted: 04/16/2015] [Indexed: 06/04/2023]
Abstract
The ultrafast dynamics of the second singlet electronically excited state (S2) in n-propylbenzene has been investigated by femtosecond time-resolved photoelectron imaging coupled with photofragmentation spectroscopy. The intermediate state for the deactivation of the S2 state is observed by transient photoelectron kinetic energy distributions and photoelectron angular distributions. An ultrafast electronic relaxation process on timescale of the fitted ∼50 fs was observed in the S2 state by time-resolved photoelectron imaging and it is attributed to the S1←S2 internal conversion (IC). The time constant of 1.23 (±0.2) ps is determined for the further deactivation of the intermediate S1 state.
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Affiliation(s)
- Yuzhu Liu
- School of Physics and Optoelectronic Engineering, Nanjing University of Information Science & Technology, 210044 Nanjing, China.
| | | | - Peter Radi
- Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Gregor Knopp
- Paul Scherrer Institute, 5232 Villigen, Switzerland
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Parker DSN, Kaiser RI, Kostko O, Ahmed M. Selective Formation of Indene through the Reaction of Benzyl Radicals with Acetylene. Chemphyschem 2015; 16:2091-3. [DOI: 10.1002/cphc.201500313] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Indexed: 11/11/2022]
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Parker DSN, Kaiser RI, Kostko O, Troy TP, Ahmed M, Mebel AM, Tielens AGGM. GAS PHASE SYNTHESIS OF (ISO)QUINOLINE AND ITS ROLE IN THE FORMATION OF NUCLEOBASES IN THE INTERSTELLAR MEDIUM. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/803/2/53] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Thompson JOF, Saalbach L, Crane SW, Paterson MJ, Townsend D. Ultraviolet relaxation dynamics of aniline,N,N-dimethylaniline and 3,5-dimethylaniline at 250 nm. J Chem Phys 2015; 142:114309. [PMID: 25796251 DOI: 10.1063/1.4914330] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Time-resolved photoelectron imaging was used to investigate the electronic relaxation dynamics of gas-phase aniline, N, N-dimethylaniline, and 3,5-dimethylaniline following ultraviolet excitation at 250 nm. Our analysis was supported by ab initio coupled-cluster calculations evaluating excited state energies and (in aniline) the evolution of a range of excited state physical properties as a function of N-H bond extension. Due to a lack of consistency between several earlier studies undertaken in aniline, the specific aim of this present work was to gain new insight into the previously proposed non-adiabatic coupling interaction between the two lowest lying singlet excited states S1(ππ(∗)) and S2(3s/πσ(∗)). The methyl-substituted systems N, N-dimethylaniline and 3,5-dimethylaniline were included in order to obtain more detailed dynamical information about the key internal molecular coordinates that drive the S1(ππ(∗))/S2(3s/πσ(∗)) coupling mechanism. Our findings suggest that in all three systems, both electronic states are directly populated during the initial excitation, with the S2(3s/πσ(∗)) state then potentially decaying via either direct dissociation along the N-X stretching coordinate (X = H or CH3) or internal conversion to the S1(ππ(∗)) state. In aniline and N, N-dimethylaniline, both pathways most likely compete in the depletion of S2(3s/πσ(∗)) state population. However, in 3,5-dimethylaniline, only the direct dissociation mechanism appears to be active. This is rationalized in terms of changes in the relative rates of the two decay pathways upon methylation of the aromatic ring system.
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Affiliation(s)
- James O. F. Thompson
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Lisa Saalbach
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Stuart W. Crane
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Martin J. Paterson
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Dave Townsend
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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Parker DSN, Kaiser RI, Kostko O, Troy TP, Ahmed M, Sun BJ, Chen SH, Chang AHH. On the formation of pyridine in the interstellar medium. Phys Chem Chem Phys 2015; 17:32000-8. [DOI: 10.1039/c5cp02960k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nitrogen bearing aromatic molecule pyridine (C5H5N) is revealed to form in high temperature environments simulating conditions in carbon-rich circumstellar envelopes via the reaction of the cyano vinyl radical with vinyl cyanide.
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Affiliation(s)
| | - Ralf I. Kaiser
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Oleg Kostko
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Tyler P. Troy
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Musahid Ahmed
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Bing-Jian Sun
- Department of Chemistry
- National Dong Hwa University
- Shoufeng
- Taiwan
| | - Shih-Hua Chen
- Department of Chemistry
- National Dong Hwa University
- Shoufeng
- Taiwan
| | - A. H. H. Chang
- Department of Chemistry
- National Dong Hwa University
- Shoufeng
- Taiwan
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46
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Zawadzki MM, Thompson JOF, Burgess EA, Paterson MJ, Townsend D. Time-resolved photoionization spectroscopy of mixed Rydberg-valence states: indole case study. Phys Chem Chem Phys 2015; 17:26659-69. [DOI: 10.1039/c5cp04645a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved photoelectron imaging reveals subtle new mechanistic insight into the ultraviolet relaxation dynamics of gas-phase indole.
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Affiliation(s)
| | | | - Emma A. Burgess
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
| | | | - Dave Townsend
- Institute of Photonics & Quantum Sciences
- Heriot-Watt University
- Edinburgh
- UK
- Institute of Chemical Sciences
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47
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Ultrafast dynamics of ethylbenzene cations probed by photofragmentation and photoelectron spectrometry. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.07.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Parker DSN, Kaiser RI, Troy TP, Ahmed M. Hydrogen abstraction/acetylene addition revealed. Angew Chem Int Ed Engl 2014; 53:7740-4. [PMID: 24953850 DOI: 10.1002/anie.201404537] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Indexed: 11/06/2022]
Abstract
For almost half a century, polycyclic aromatic hydrocarbons (PAHs) have been proposed to play a key role in the astrochemical evolution of the interstellar medium (ISM) and in the chemistry of combustion systems. However, even the most fundamental reaction mechanism assumed to lead to the simplest PAH naphthalene--the hydrogen abstraction-acetylene addition (HACA) mechanism--has eluded experimental observation. Here, by probing the phenylacetylene (C8 H6 ) intermediate together with naphthalene (C10 H8 ) under combustion-like conditions by photo-ionization mass spectrometry, the very first direct experimental evidence for the validity of the HACA mechanism which so far had only been speculated theoretically is reported.
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Affiliation(s)
- Dorian S N Parker
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, (USA) http://www.chem.hawaii.edu/Bil301/welcome.html
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49
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Parker DSN, Kaiser RI, Troy TP, Ahmed M. Hydrogen Abstraction/Acetylene Addition Revealed. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404537] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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50
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Ng MY, Nelson J, Taatjes CA, Osborn DL, Meloni G. Synchrotron Photoionization Study of Mesitylene Oxidation Initiated by Reaction with Cl(2P) or O(3P) Radicals. J Phys Chem A 2014; 118:3735-3748. [DOI: 10.1021/jp500260f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Martin Y. Ng
- Department
of Chemistry, University of San Francisco, San Francisco, California 94117, United States
| | - Jordan Nelson
- Department
of Chemistry, University of San Francisco, San Francisco, California 94117, United States
| | - Craig A. Taatjes
- Combustion
Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - David L. Osborn
- Combustion
Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Giovanni Meloni
- Department
of Chemistry, University of San Francisco, San Francisco, California 94117, United States
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