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Okada K, Sakimoto K, Schuessler HA. Rotational Cooling Effect on the Rate Constant in the CH 3F + Ca + Reaction at Low Collision Energies. J Phys Chem A 2022; 126:4881-4890. [PMID: 35857026 DOI: 10.1021/acs.jpca.2c01063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The rotational cooling effect on the reaction rate constant of the gas-phase ion-polar-molecule reaction CH3F + Ca+ → CH3 + CaF+ was experimentally studied at low collision energies. Fluoromethane molecules showed higher reactivity as the rotational temperature decreased. The experimental rate constants were compared with the capture rate constants which were obtained by the Perturbed Rotational State (PRS) theory assuming the rotational level distribution corresponding to the experimental conditions. The PRS result shows a strong dependence of the capture rate constants on the rotational level distribution in accordance with the experimental findings. However, the PRS capture rate constants deviate from the measurement values as the average collision energy increases especially when the fluoromethane molecules are rotationally cooled far below room temperature. The present paper suggests that the rotational state distribution significantly affects the rate constants of ion-polar-molecule reactions and is one of the important issues to be considered in the study of molecular synthesis in the interstellar medium, where the thermal equilibrium is not necessarily established.
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Affiliation(s)
- Kunihiro Okada
- Department of Materials and Life Sciences, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo 102-8554, Japan
| | - Kazuhiro Sakimoto
- Department of Materials and Life Sciences, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo 102-8554, Japan
| | - Hans A Schuessler
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843-4242, United States
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2
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Tsikritea A, Diprose JA, Softley TP, Heazlewood BR. Capture Theory Models: An overview of their development, experimental verification, and applications to ion-molecule reactions. J Chem Phys 2022; 157:060901. [DOI: 10.1063/5.0098552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Since Arrhenius first proposed an equation to account for the behaviour of thermally activated reactions in 1889, significant progress has been made in our understanding of chemical reactivity. A number of capture theory models have been developed over the past several decades to predict the rate coefficients for reactions between ions and molecules-ranging from the Langevin equation (for reactions between ions and non-polar molecules) to more recent fully quantum theories (for reactions at ultra-cold temperatures). A number of different capture theory methods are discussed, with the key assumptions underpinning each approach clearly set out. The strengths and limitations of these capture theory methods are examined through detailed comparisons between low-temperature experimental measurements and capture theory predictions. Guidance is provided on the selection of an appropriate capture theory method for a given class of ion-molecule reaction and set of experimental conditions-identifying when a capture-based model is likely to provide an accurate prediction. Finally, the impact of capture theories on fields such as astrochemical modelling is noted, with some potential future directions of capture-based approaches outlined.
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Affiliation(s)
| | - Jake A Diprose
- University of Liverpool Department of Physics, United Kingdom
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Agúndez M, Roueff E, Cabezas C, Cernicharo J, Marcelino N. First detection of doubly deuterated methyl acetylene (CHD 2CCH and CH 2DCCD) ★. Astron Astrophys 2021; 649:A171. [PMID: 34334795 PMCID: PMC7611416 DOI: 10.1051/0004-6361/202140843] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report the first detection in space of the two doubly deuterated isotopologues of methyl acetylene. The species CHD2CCH and CH2DCCD were identified in the dense core L483 through nine and eight, respectively, rotational lines in the 72-116 GHz range using the IRAM 30m telescope. The astronomical frequencies observed here were combined with laboratory frequencies from the literature measured in the 29-47 GHz range to derive more accurate spectroscopic parameters for the two isotopologues. We derive beam-averaged column densities of (2.7 ± 0.5) × 1012 cm-2 for CHD2CCH and (2.2 ± 0.4) × 1012 cm-2 for CH2DCCD, which translate to abundance ratios CH3CCH/CHD2CCH = 34 ± 10 and CH3CCH/CH2DCCD = 42 ± 13. The doubly deuterated isotopologues of methyl acetylene are only a few times less abundant than the singly deuterated ones, concretely around 2.4 times less abundant than CH3CCD. The abundances of the different deuterated isotopologues with respect to CH3CCH are reasonably accounted for by a gas-phase chemical model in which deuteration occurs from the precursor ions C3H6D+ and C3H5D+, when the ortho-to-para ratio of molecular hydrogen is sufficiently low. This points to gas-phase chemical reactions, rather than grain-surface processes, as responsible for the formation and deuterium fractionation of CH3CCH in L483. The abundance ratios CH2DCCH/CH3CCD = 3.0 ± 0.9 and CHD2CCH/CH2DCCD = 1.25 ± 0.37 observed in L483 are consistent with the statistically expected values of three and one, respectively, with the slight overabundance of CHD2CCH compared to CH2DCCD being well explained by the chemical model.
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Affiliation(s)
- M. Agúndez
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - E. Roueff
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Université, F-92190, Meudon, France
| | - C. Cabezas
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - J. Cernicharo
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - N. Marcelino
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
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4
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Okada K, Sakimoto K, Takada Y, Schuessler HA. A study of the translational temperature dependence of the reaction rate constant between CH 3CN and Ne + at low temperatures. J Chem Phys 2020; 153:124305. [PMID: 33003759 DOI: 10.1063/5.0013807] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We have measured the translational temperature dependence of the reaction rate constant for CH3CN + Ne+ → products at low temperatures. A cold Ne+ ensemble was embedded in Ca+ Coulomb crystals by a sympathetic laser cooling technique, while cold acetonitrile (CH3CN) molecules were produced by two types of Stark velocity filters to widely change the translational temperatures. The measured reaction rate constant gradually increases with the decrease in the translational temperature of the velocity-selected CH3CN molecules from 60 K down to 2 K, and thereby, a steep increase was observed at temperatures lower than 5 K. A comparison between experimental rate constants and the ion-dipole capture rate constants by the Perturbed Rotational State (PRS) theory was performed. The PRS capture rate constant reproduces well the reaction rate constant at a few kelvin but not for temperatures higher than 5 K. The result indicates that the reaction probability is small compared to typical ion-polar molecule reactions at temperatures above 5 K.
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Affiliation(s)
- Kunihiro Okada
- Department of Physics, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo 102-8554, Japan
| | - Kazuhiro Sakimoto
- Department of Physics, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo 102-8554, Japan
| | - Yusuke Takada
- Department of Physics, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo 102-8554, Japan
| | - Hans A Schuessler
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843-4242, USA
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Asvany O, Markus CR, Salomon T, Schmid PC, Banhatti S, Brünken S, Lipparini F, Gauss J, Schlemmer S. High-resolution rovibrational spectroscopy of c- : The C–H antisymmetric stretching band. J Mol Struct 2020; 1214:128023. [DOI: 10.1016/j.molstruc.2020.128023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Markus CR, Asvany O, Salomon T, Schmid PC, Brünken S, Lipparini F, Gauss J, Schlemmer S. Vibrational Excitation Hindering an Ion-Molecule Reaction: The c-C_{3}H_{2}^{+}-H_{2} Collision Complex. Phys Rev Lett 2020; 124:233401. [PMID: 32603166 DOI: 10.1103/physrevlett.124.233401] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/27/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
Experiments within a cryogenic 22-pole ion trap have revealed an interesting reaction dynamic phenomenon, where rovibrational excitation of an ionic molecule slows down a reaction with a neutral partner. This is demonstrated for the low-temperature hydrogen abstraction reaction c-C_{3}H_{2}^{+}+H_{2}, where excitation of the ion into the ν_{7} antisymmetric C-H stretching mode decreased the reaction rate coefficient toward the products c-C_{3}H_{3}^{+}+H. Supported by high-level quantum-chemical calculations, this observation is explained by the reaction proceeding through a c-C_{3}H_{2}^{+}-H_{2} collision complex in the entrance channel, in which the hydrogen molecule is loosely bound to the hydrogen atom of the c-C_{3}H_{2}^{+} ion. This discovery enables high-resolution vibrational action spectroscopy for c-C_{3}H_{2}^{+} and other molecular ions with similar reaction pathways. Moreover, a detailed kinetic model relating the extent of the observed product depletion signal to the rate coefficients of inelastic collisions reveals that rotational relaxation of the vibrationally excited ions is significantly faster than the rovibrational relaxation, allowing for a large fraction of the ions to be vibrationally excited. This result provides fundamental insight into the mechanism for an important class of chemical reactions, and is capable of probing the inelastic collisional dynamics of molecular ions.
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Affiliation(s)
- Charles R Markus
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
- University of Illinois, Department of Chemistry, Urbana, Illinois 61801, USA
| | - Oskar Asvany
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
| | - Thomas Salomon
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
| | - Philipp C Schmid
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
| | - Sandra Brünken
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands
| | - Filippo Lipparini
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, I-56124 Pisa, Italy
- Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany
| | - Jürgen Gauss
- Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany
| | - Stephan Schlemmer
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
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Brünken S, Lipparini F, Stoffels A, Jusko P, Redlich B, Gauss J, Schlemmer S. Gas-Phase Vibrational Spectroscopy of the Hydrocarbon Cations l-C 3H +, HC 3H +, and c-C 3H 2+: Structures, Isomers, and the Influence of Ne-Tagging. J Phys Chem A 2019; 123:8053-8062. [PMID: 31422660 PMCID: PMC6755619 DOI: 10.1021/acs.jpca.9b06176] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
![]()
We
report the first gas-phase vibrational spectra of the hydrocarbon
ions C3H+ and C3H2+. The ions were produced by electron impact ionization of
allene. Vibrational spectra of the mass-selected ions tagged with
Ne were recorded using infrared predissociation spectroscopy in a
cryogenic ion trap instrument using the intense and widely tunable
radiation of a free electron laser. Comparison of high-level quantum
chemical calculations and resonant depletion measurements revealed
that the C3H+ ion is exclusively formed in its
most stable linear isomeric form, whereas two isomers were observed
for C3H2+. Bands of the energetically
favored cyclic c-C3H2+ are in excellent
agreement with calculated anharmonic frequencies, whereas for the
linear open-shell HCCCH+ (2Πg) a detailed theoretical description of the spectrum remains challenging
because of Renner–Teller and spin–orbit interactions.
Good agreement between theory and experiment, however, is observed
for the frequencies of the stretching modes for which an anharmonic
treatment was possible. In the case of linear l-C3H+, small but non-negligible effects of the attached Ne on the
ion fundamental band positions and the overall spectrum were found.
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Affiliation(s)
- Sandra Brünken
- FELIX Laboratory, Institute for Molecules and Materials , Radboud University , Toernooiveld 7c , NL-6525ED Nijmegen , The Netherlands.,I. Physikalisches Institut , Universität zu Köln , Zülpicher Str. 77 , D-50937 Köln , Germany
| | - Filippo Lipparini
- Institut für Physikalische Chemie , Johannes Gutenberg-Universität Mainz , Duesbergweg 10-14 , D-55128 Mainz , Germany.,Dipartimento di Chimica e Chimica Industriale , Università di Pisa , Via G. Moruzzi 13 , I-56124 Pisa , Italy
| | - Alexander Stoffels
- FELIX Laboratory, Institute for Molecules and Materials , Radboud University , Toernooiveld 7c , NL-6525ED Nijmegen , The Netherlands.,I. Physikalisches Institut , Universität zu Köln , Zülpicher Str. 77 , D-50937 Köln , Germany
| | - Pavol Jusko
- I. Physikalisches Institut , Universität zu Köln , Zülpicher Str. 77 , D-50937 Köln , Germany
| | - Britta Redlich
- FELIX Laboratory, Institute for Molecules and Materials , Radboud University , Toernooiveld 7c , NL-6525ED Nijmegen , The Netherlands
| | - Jürgen Gauss
- Institut für Physikalische Chemie , Johannes Gutenberg-Universität Mainz , Duesbergweg 10-14 , D-55128 Mainz , Germany
| | - Stephan Schlemmer
- I. Physikalisches Institut , Universität zu Köln , Zülpicher Str. 77 , D-50937 Köln , Germany
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Jusko P, Brünken S, Asvany O, Thorwirth S, Stoffels A, van der Meer L, Berden G, Redlich B, Oomens J, Schlemmer S. The FELion cryogenic ion trap beam line at the FELIX free-electron laser laboratory: infrared signatures of primary alcohol cations. Faraday Discuss 2019; 217:172-202. [DOI: 10.1039/c8fd00225h] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The FELion beamline – a cryogenic 22-pole trap for vibrational spectroscopy of molecular ions at the FELIX Laboratory.
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Affiliation(s)
- Pavol Jusko
- I. Physikalisches Institut
- Universität zu Köln
- 50937 Köln
- Germany
| | - Sandra Brünken
- I. Physikalisches Institut
- Universität zu Köln
- 50937 Köln
- Germany
- Radboud University
| | - Oskar Asvany
- I. Physikalisches Institut
- Universität zu Köln
- 50937 Köln
- Germany
| | - Sven Thorwirth
- I. Physikalisches Institut
- Universität zu Köln
- 50937 Köln
- Germany
| | - Alexander Stoffels
- I. Physikalisches Institut
- Universität zu Köln
- 50937 Köln
- Germany
- Radboud University
| | - Lex van der Meer
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Giel Berden
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Britta Redlich
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Jos Oomens
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
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9
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Garcia GA, Gans B, Krüger J, Holzmeier F, Röder A, Lopes A, Fittschen C, Alcaraz C, Loison JC. Valence shell threshold photoelectron spectroscopy of C3Hx (x = 0–3). Phys Chem Chem Phys 2018. [DOI: 10.1039/c8cp00510a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present the photoelectron spectra of C3Hx (x = 0–3) formed in a microwave discharge flow-tube reactor by consecutive H abstractions from C3H4 (C3Hx + F → C3Hx−1 + HF (x = 1–4)), but also from F + CH4 schemes by secondary reactions.
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Affiliation(s)
| | | | - Julia Krüger
- Synchrotron SOLEIL
- L'Orme des Merisiers
- Gif sur Yvette
- France
| | - Fabian Holzmeier
- Synchrotron SOLEIL
- L'Orme des Merisiers
- Gif sur Yvette
- France
- Laboratoire de Chimie Physique d'Orsay
| | - Anja Röder
- Synchrotron SOLEIL
- L'Orme des Merisiers
- Gif sur Yvette
- France
| | - Allan Lopes
- CNRS – Université Paris-Sud et Paris-Saclay
- Laboratoire de Chimie Physique
- UMR 8000
- Centre Universitaire Paris-Sud
- 91405 Orsay
| | | | - Christian Alcaraz
- CNRS – Université Paris-Sud et Paris-Saclay
- Laboratoire de Chimie Physique
- UMR 8000
- Centre Universitaire Paris-Sud
- 91405 Orsay
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Hickson KM, Loison JC, Wakelam V. Temperature dependent product yields for the spin forbidden singlet channel of the C(3P) + C2H2 reaction. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.07.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Guzmán VV, Pety J, Goicoechea JR, Gerin M, Roueff E, Gratier P, Öberg KI. SPATIALLY RESOLVED
l
-C
3
H
+
EMISSION IN THE HORSEHEAD PHOTODISSOCIATION REGION: FURTHER EVIDENCE FOR A TOP-DOWN HYDROCARBON CHEMISTRY. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/2041-8205/800/2/l33] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Asvany O, Bielau F, Moratschke D, Krause J, Schlemmer S. Note: New design of a cryogenic linear radio frequency multipole trap. Rev Sci Instrum 2010; 81:076102. [PMID: 20687768 DOI: 10.1063/1.3460265] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A new design of a cryogenic linear 22-pole ion trap has been constructed and tested. It is essentially a copper housing to which opposite inner walls two electrode sets are attached via sapphire insulators. These stainless steel electrodes are electroformed in one piece to guarantee good heat conduction. Connected to an external coil, they form an LC-circuit of about 19 MHz resonance frequency. This circuit is excited with a rf power supply made of a commercial digital synthesizer followed by a 10 W amplifier. Buffer gas-cooled H(2)D(+) ions have been stored in this trap at a nominal trap temperature of 14 K. Spectroscopy of the ions confirmed that the kinetic (Doppler) temperature is in reasonable agreement with this value.
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Affiliation(s)
- Oskar Asvany
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany.
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14
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Weber T, Meyer W, Rosmus† P. Vibrational motion of the radical cation C in its degenerate electronic ground state. Mol Phys 2010. [DOI: 10.1080/00268971003702213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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15
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Faure A, Vuitton V, Thissen R, Wiesenfeld L, Dutuit O. Fast ion–molecule reactions in planetary atmospheres: a semiempirical capture approach. Faraday Discuss 2010; 147:337-48; discussion 379-403. [DOI: 10.1039/c003908j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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16
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Furuya K, Ide A, Okumura H, Harata A. Mass spectrometric investigation and formation mechanisms of high-mass species in the downstream region of Ar/CF(4)/O(2) plasmas. Phys Chem Chem Phys 2009; 11:934-42. [PMID: 19177211 DOI: 10.1039/b814147a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mass analysis has been conducted on the positive ions and neutral species in the downstream region of Ar/CF(4)/O(2) plasmas. The neutral species have been ionized by Li(+) attachment before mass analysis. The CF(2)O(+), C(2)F(5)O(+) and C(n)F(2n-1)O(+) (1 <or=n<or= 6) positive ions and the C(n)F(2n)O (1 <or=n<or= 7) neutral species have been found as the species composed of C, F and O. The intensity of C(2)F(4)O observed via the Li(+)-attachment mass spectra has been exceptionally weak in comparison to the intensities of CF(2)O and C(3)F(6)O. In addition, neither C(2)F(4) nor C(3)F(6) have been observed, although C(n)F(2n) (n>or= 4) have been observed as the species composed only of C and F. These findings suggest that C(n)F(2n)O (n>or= 3) are produced mainly through the following reactions: CF(3)(CF(2))(m)CF = CF(2) + O((3)P) --> CF(2)((3)B(1)) + CF(3)(CF(2))(m)CFO (m>or= 1) and CF(3)(CF(2))(m)CF = CF(CF(2))(n)CF(3) + O((3)P) --> CF(3)(CF(2))(m)CF + CF(3)(CF(2))(n)CFO (m, n>or= 1), where the CF(3)(CF(2))(n)- group might have side chains, as in (CF(3))(2)CF(CF(2))(n-2)-. With the help of quantum chemistry calculations of reaction enthalpies and transition states, the formation mechanisms of the observed species have been discussed in detail.
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Affiliation(s)
- Kenji Furuya
- Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan.
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17
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Smith IWM, Sage AM, Donahue NM, Herbst E, Quan D. The temperature-dependence of rapid low temperature reactions: experiment, understanding and prediction. Faraday Discuss 2006; 133:137-56; discussion 191-230, 449-52. [PMID: 17191447 DOI: 10.1039/b600721j] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Despite the success of the CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme) method in measuring rate coefficients for neutral-neutral reactions of radicals down close to the very low temperatures prevalent in dense interstellar clouds (ISCs), there are still many reactions of potential importance in the chemistry of these objects for which there have been no measurements of low temperature rate coefficients. One important class of reactions is that between atomic and molecular free radicals and unsaturated hydrocarbons; that is, alkynes and alkenes. Based on semi-empirical arguments and correlations of 'room temperature' rate coefficients, k(298 K), for reactions of this type with the difference between the ionisation energy of the alkyne/alkene and the electron affinity of the radical, we suggest which reactions between the radicals, C(3P), O(3P), N(4S), CH, C2H and CN, and carbon chain molecules (Cn) and cyanopolyynes (HC2nCN and NCC2nCN) are likely to be fast at the temperature of dense ISCs. These reactions and rate coefficients have been incorporated into a purely gas-phase model (osu2005) of ISC chemistry. The results of these calculations are presented and discussed.
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Affiliation(s)
- Ian W M Smith
- University Chemical Laboratories, Lensfield Road, Cambridge, UK.
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