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Fricke C, Rajbanshi B, Walker EA, Terejanu G, Heyden A. Propane Dehydrogenation on Platinum Catalysts: Identifying the Active Sites through Bayesian Analysis. ACS Catal 2022. [DOI: 10.1021/acscatal.1c04844] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Charles Fricke
- Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Biplab Rajbanshi
- Department of Chemistry, Visva-Bharati University, Santiniketan 731235, Birbhum, West Bengal, India
| | - Eric A. Walker
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
- Institute for Computational and Data Sciences, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Gabriel Terejanu
- Department of Computer Science, University of North Carolina at Charlotte, Charlotte, North Carolina, 28223, United States
| | - Andreas Heyden
- Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, United States
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Bourgalais J, Carrasco N, Vettier L, Comby A, Descamps D, Petit S, Blanchet V, Gaudin J, Mairesse Y, Marty B. Aromatic Formation Promoted by Ion-Driven Radical Pathways in EUV Photochemical Experiments Simulating Titan's Atmospheric Chemistry. J Phys Chem A 2021; 125:3159-3168. [PMID: 33843236 DOI: 10.1021/acs.jpca.1c00324] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the atmosphere of Titan, Saturn's main satellite, molecular growth is initiated by 85.6 nm extreme ultraviolet (EUV) photons triggering a chemistry with charged and free-radical species. However, the respective contribution of these species to the complexification of matter is far from being known. This work presents a chemical analysis in order to contribute to a better understanding of aromatic formation pathways. A gas mixture of N2/CH4 (90/10%) within the closed SURFACAT reactor was irradiated at a relatively low pressure (0.1 mbar) and room temperature for 6 h by EUV photons (∼85.6 nm). The neutral molecules formed at the end of the irradiation were condensed in a cryogenic trap and analyzed by electron ionization mass spectrometry. An analysis of the dominant chemical pathways highlights the identification of benzene and toluene and underlies the importance of small ion and radical reactions. On the basis of the experimental results, a speculative mechanism based on sequential H-elimination/CH3-addition reactions is proposed for the growth of aromatics in Titan's atmosphere. Elementary reactions to be studied are given to instill future updates of photochemical models of Titan's atmosphere.
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Affiliation(s)
- Jérémy Bourgalais
- LATMOS-IPSL, Université Versailles St-Quentin, CNRS/INSU, Sorbonne Université, UPMC Univ. Paris 06, 11 boulevard d'Alembert, 78280 Guyancourt, France.,Centre de Recherches Pétrographiques et Géochimiques, UMR 7358 CNRS-Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, F-54501 Vandoeuvre-lès-Nancy, France
| | - Nathalie Carrasco
- LATMOS-IPSL, Université Versailles St-Quentin, CNRS/INSU, Sorbonne Université, UPMC Univ. Paris 06, 11 boulevard d'Alembert, 78280 Guyancourt, France
| | - Ludovic Vettier
- LATMOS-IPSL, Université Versailles St-Quentin, CNRS/INSU, Sorbonne Université, UPMC Univ. Paris 06, 11 boulevard d'Alembert, 78280 Guyancourt, France
| | - Antoine Comby
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Dominique Descamps
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Stéphane Petit
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Valérie Blanchet
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Jérôme Gaudin
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Yann Mairesse
- CELIA, Université de Bordeaux - CNRS - CEA, UMR5107, 351 Cours de la Libération, F33405 Talence, France
| | - Bernard Marty
- Centre de Recherches Pétrographiques et Géochimiques, UMR 7358 CNRS - Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, F-54501 Vandoeuvre-lès-Nancy, France
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Abstract
The water gas shift (WGS) is an equilibrium exothermic reaction, whose corresponding industrial process is normally carried out in two adiabatic stages, to overcome the thermodynamic and kinetic limitations. The high temperature stage makes use of iron/chromium-based catalysts, while the low temperature stage employs copper/zinc-based catalysts. Nevertheless, both these systems have several problems, mainly dealing with safety issues and process efficiency. Accordingly, in the last decade abundant researches have been focused on the study of alternative catalytic systems. The best performances have been obtained with noble metal-based catalysts, among which, platinum-based formulations showed a good compromise between performance and ease of preparation. These catalytic systems are extremely attractive, as they have numerous advantages, including the feasibility of intermediate temperature (250–400 °C) applications, the absence of pyrophoricity, and the high activity even at low loadings. The particle size plays a crucial role in determining their catalytic activity, enhancing the performance of the nanometric catalytic systems: the best activity and stability was reported for particle sizes < 1.7 nm. Moreover the optimal Pt loading seems to be located near 1 wt%, as well as the optimal Pt coverage was identified in 0.25 ML. Kinetics and mechanisms studies highlighted the low energy activation of Pt/Mo2C-based catalytic systems (Ea of 38 kJ·mol−1), the associative mechanism is the most encountered on the investigated studies. This review focuses on a selection of recent published articles, related to the preparation and use of unstructured platinum-based catalysts in water gas shift reaction, and is organized in five main sections: comparative studies, kinetics, reaction mechanisms, sour WGS and electrochemical promotion. Each section is divided in paragraphs, at the end of the section a summary and a summary table are provided.
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On an EUV Atmospheric Simulation Chamber to Study the Photochemical Processes of Titan's Atmosphere. Sci Rep 2020; 10:10009. [PMID: 32561886 PMCID: PMC7305212 DOI: 10.1038/s41598-020-66950-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 06/01/2020] [Indexed: 11/16/2022] Open
Abstract
The in situ exploration of Titan’s atmosphere requires the development of laboratory experiments to understand the molecular growth pathways initiated by photochemistry in the upper layers of the atmosphere. Key species and dominant reaction pathways are used to feed chemical network models that reproduce the chemical and physical processes of this complex environment. Energetic UV photons initiate highly efficient chemistry by forming reactive species in the ionospheres of the satellite. We present here a laboratory experiment based on a new closed and removable photoreactor coupled here to an Extreme Ultraviolet (EUV) irradiation beam produced by the high-order harmonic generation of a femtosecond laser. This type of EUV stable source allow long-term irradiation experiments in which a plethora of individual reactions can take place. In order to demonstrate the validity of our approach, we irradiated for 7 hours at 89.2 nm, a gas mixture based on N2/CH4 (5%). Using only one wavelength, products of the reaction reveal an efficient photochemistry with the formation of large hydrocarbons but especially organic compounds rich in nitrogen similar to Titan. Among these nitrogen compounds, new species had never before been identified in the mass spectra obtained in situ in Titan’s atmosphere. Their production in this experiment, on the opposite, corroborates previous experimental measurements in the literature on the chemical composition of aerosol analogues produced in the laboratory. Diazo-compounds such as dimethyldiazene (C2H6N2), have been observed and are consistent with the large nitrogen incorporation observed by the aerosols collector pyrolysis instrument of the Huygens probe. This work represents an important step forward in the use of a closed cell chamber irradiated by the innovative EUV source for the generation of photochemical analogues of Titan aerosols. This approach allows to better constrain and understand the growth pathways of nitrogen incorporation into organic aerosols in Titan’s atmosphere.
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Walker EA, Mitchell D, Terejanu GA, Heyden A. Identifying Active Sites of the Water–Gas Shift Reaction over Titania Supported Platinum Catalysts under Uncertainty. ACS Catal 2018. [DOI: 10.1021/acscatal.7b03531] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Eric A. Walker
- Department of Chemical Engineering, University of South Carolina, 301 Main Street, Columbia, South Carolina 29208, United States
| | - Donald Mitchell
- Department of Chemical Engineering, City College of New York, 160 Covenant Avenue, New York, New York 10031, United States
| | - Gabriel A. Terejanu
- Department of Computer Science and Engineering, University of South Carolina, 301 Main Street, Columbia, South Carolina 29208, United States
| | - Andreas Heyden
- Department of Chemical Engineering, University of South Carolina, 301 Main Street, Columbia, South Carolina 29208, United States
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Fuente A, Goicoechea JR, Pety J, Le Gal R, Martín-Doménech R, Gratier P, Guzmán V, Roueff E, Loison JC, Muñoz Caro GM, Wakelam V, Gerin M, Riviere-Marichalar P, Vidal T. First Detection of Interstellar S 2H. THE ASTROPHYSICAL JOURNAL. LETTERS 2017; 851:L49. [PMID: 29862006 PMCID: PMC5975949 DOI: 10.3847/2041-8213/aaa01b] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We present the first detection of gas phase S2H in the Horsehead, a moderately UV-irradiated nebula. This confirms the presence of doubly sulfuretted species in the interstellar medium and opens a new challenge for sulfur chemistry. The observed S2H abundance is ~5×10-11, only a factor 4-6 lower than that of the widespread H2S molecule. H2S and S2H are efficiently formed on the UV-irradiated icy grain mantles. We performed ice irradiation experiments to determine the H2S and S2H photodesorption yields. The obtained values are ~1.2×10-3 and <1×10-5 molecules per incident photon for H2S and S2H, respectively. Our upper limit to the S2H photodesorption yield suggests that photo-desorption is not a competitive mechanism to release the S2H molecules to the gas phase. Other desorption mechanisms such as chemical desorption, cosmic-ray desorption and grain shattering can increase the gaseous S2H abundance to some extent. Alternatively, S2H can be formed via gas phase reactions involving gaseous H2S and the abundant ions S+ and SH+. The detection of S2H in this nebula could be therefore the result of the coexistence of an active grain surface chemistry and gaseous photo-chemistry.
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Affiliation(s)
- Asunción Fuente
- Observatorio Astronómico Nacional (OAN,IGN), Apdo 112, E-28803 Alcalá de Henares, Spain
| | - Javier R. Goicoechea
- Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Ins de la Cruz, 3, E-28049 Cantoblanco, Madrid, Spain
| | - Jerome Pety
- Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint Martin d’Hères, France
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France
| | - Romane Le Gal
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
| | | | - Pierre Gratier
- Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - Viviana Guzmán
- Joint ALMA Observatory (JAO), Alonso de Córdova 3107, Vitacura, Santiago, Chile
| | - Evelyne Roueff
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190 Meudon, France
| | - Jean Christophe Loison
- Institut des Sciences Moléculaires de Bordeaux (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, 33400, Talence, France
| | - Guillermo M. Muñoz Caro
- Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir, km 4, Torrejón de Ardoz, 28850 Madrid, Spain
| | - Valentine Wakelam
- Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - Maryvonne Gerin
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France
| | - Pablo Riviere-Marichalar
- Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Ins de la Cruz, 3, E-28049 Cantoblanco, Madrid, Spain
| | - Thomas Vidal
- Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
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Loison JC, Agúndez M, Wakelam V, Roueff E, Gratier P, Marcelino N, Nuñez Reyes D, Cernicharo J, Gerin M. The interstellar chemistry of C 3H and C 3H 2 isomers. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 2017; 470:4075-4088. [PMID: 29142332 PMCID: PMC5683352 DOI: 10.1093/mnras/stx1265] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report the detection of linear and cyclic isomers of C3H and C3H2 towards various starless cores and review the corresponding chemical pathways involving neutral (C3Hx with x=1,2) and ionic (C3Hx+ with x = 1,2,3) isomers. We highlight the role of the branching ratio of electronic Dissociative Recombination (DR) reactions of C3H2+ and C3H3+ isomers showing that the statistical treatment of the relaxation of C3H* and C3H2* produced in these DR reactions may explain the relative c,l-C3H and c,l-C3H2 abundances. We have also introduced in the model the third isomer of C3H2 (HCCCH). The observed cyclic-to-linear C3H2 ratio vary from 110 ± 30 for molecular clouds with a total density around 1×104 molecules.cm-3 to 30 ± 10 for molecular clouds with a total density around 4×105 molecules.cm-3, a trend well reproduced with our updated model. The higher ratio for low molecular cloud densities is mainly determined by the importance of the H + l-C3H2 → H + c-C3H2 and H + t-C3H2 → H + c-C3H2 isomerization reactions.
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Affiliation(s)
- Jean-Christophe Loison
- Institut des Sciences Moléculaires (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, 33400, Talence, France
| | - Marcelino Agúndez
- Instituto de Ciencia de Materiales de Madrid, CSIC, C\ Sor Juana Inés de la Cruz 3, 28049 Cantoblanco, Spain
| | - Valentine Wakelam
- Laboratoire d'astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - Evelyne Roueff
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190 Meudon, France
| | - Pierre Gratier
- Laboratoire d'astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - Núria Marcelino
- INAF, Osservatorio di Radioastronomia, via P. Gobetti 101, 40129 Bologna, Italy
| | - Dianailys Nuñez Reyes
- Institut des Sciences Moléculaires (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, 33400, Talence, France
| | - José Cernicharo
- Instituto de Ciencia de Materiales de Madrid, CSIC, C\ Sor Juana Inés de la Cruz 3, 28049 Cantoblanco, Spain
| | - Maryvonne Gerin
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France
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8
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Pernot P, Peng Z, Plessis S, Carrasco N. Dissociative recombination exalts molecular growth in N 2/CH 4plasmas. EPJ WEB OF CONFERENCES 2015. [DOI: 10.1051/epjconf/20158406003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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9
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Baptista L, da Silveira EF. A theoretical study of three gas-phase reactions involving the production or loss of methane cations. Phys Chem Chem Phys 2014; 16:21867-75. [PMID: 25200833 DOI: 10.1039/c4cp02607a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrocarbon ions are important species in flames, spectroscopy and the interstellar medium. Their importance is reflected in the extensive body of literature on the structure and reactivity of carbocations. However, the geometry, electronic structure and reactivity of carbocations are difficult to assess. This study aims to contribute to the current knowledge of this subject by presenting a quantum mechanics description of methane cation dissociation using multiconfigurational methods. The geometric and electronic parameters of the minimum structure were determined for three main reaction paths: the dissociation CH4(+)→ CH2(+) + H2 and the dissociation-recombination processes CH4(+)↔ CH3(+) + H. The electronic and energetic effects of these reactions were analyzed, and it was found that each reaction path has a strong dependence on the methodology used as well as a strong multiconfigurational character during dissociation. The first doublet excited states are inner-shell excited states and may correspond to the ions that are expected to be formed after electron detachment. The rate coefficient for each reaction path was determined using variational transition state theory and RRKM/master equation calculations. The major dissociation paths, with their rate coefficients at the high-pressure limit, are CH4(+)(X(~)(2)B1) → CH3(+)(A(2)A1') + H((2)S) (k∞(T) = 1.42 × 10(+14) s(-1) exp(-37.12/RT)) and CH4(+)(X(~)(2)B1) → CH2(+)(A(2)A1) + H2((2)Σg(+)) (k∞(T) = 9.18 × 10(+14) s(-1) exp(-55.77/RT)). Our findings help to explain the abundance of ions formed from CH4 in the interstellar medium and to build models of chemical evolution.
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Affiliation(s)
- Leonardo Baptista
- Universidade do Estado do Rio de Janeiro, Faculdade de Tecnologia, Departamento de Química e Ambiental, Rodovia Presidente Dutra Km 298, Resende, RJ, Brazil.
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Peng Z, Carrasco N, Pernot P. Modeling of synchrotron-based laboratory simulations of Titan’s ionospheric photochemistry. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.grj.2014.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Couturier-Tamburelli I, Sessouma B, Chiavassa T, Piétri N. Zwitterion formation in titan ice analogs: reaction between HC3N and NH3. J Phys Chem A 2012; 116:10721-7. [PMID: 23075265 DOI: 10.1021/jp305517k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
A zwitterion is formed in the laboratory at low temperatures in the solid phase from the thermal reaction of HC(3)N and NH(3). We report for the first time its infrared spectrum. We study its reaction using Fourier transform infrared spectroscopy. Its reaction rate is estimated to be k(T) = 2.9 × 10(5) exp(-2.3 ± 0.1 (kJ mol(-1))/RT). Calculations using density functional theory (B3LYP/6-31g**) are used to characterize all the species (complexes, zwitterions, and transition states) and are in good agreement with the infrared spectra. The structure of the zwitterion is determined planar and it is characterized by a N-C bond around 1.5 Å.
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Affiliation(s)
- Isabelle Couturier-Tamburelli
- UMR CNRS 7345, Physique des Interactions Ioniques et Moléculaires, Equipe de Spectrométries et Dynamique Moléculaires, Aix Marseille Université, Case 252, Centre de St-Jérôme, 13397 Marseille cedex 20, France.
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Parnis JM, King KA, Campbell SE, Thompson MGK. Ethane cation decomposition characterization by EBMI spectroscopy: gas-phase dissociative recombination as a source of secondary products. JOURNAL OF MASS SPECTROMETRY : JMS 2012; 47:89-95. [PMID: 22282094 DOI: 10.1002/jms.2030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The decomposition products of the d(6) -ethane cation following charge-transfer ionization with Ar(+) , under conditions of varying ionization electron current, have been isolated in solid argon matrices at 18 K and examined using Fourier transform infrared spectroscopy. Gas samples containing 1 : 1600 d(6) -ethane : Ar were subjected to electron bombardment by using either a high (pin) or a low (plate) ionization density anode configuration with ionization currents between 20 and 150 μA. Under high ionization density conditions, the observed major products were d(4) -ethene (C(2) D(4) ) and d(2) -acetylene (C(2) D(2) ), with smaller yields of C(2) D(5) , C(2) D(3) , and C(2) D. The yield of each dehydrogenation product was enhanced with increased current. Analogous experiments employing the low ionization density plate anode resulted in reduced C(2) D(6) destruction and the formation of only C(2) D(4) and C(2) D(2) . The results suggest the onset of dissociative recombination processes under high ion density conditions. In this context, the results can be interpreted as a dissociative recombination of primary ion products, which gives rise to further dehydrogenation, and appearance of additional neutral radical products.
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Affiliation(s)
- J Mark Parnis
- Department of Chemistry, Trent University, Chemical Sciences Building, 1600 West Bank Drive, Peterborough, ON K9J 5G8, Canada.
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