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Title: THE C({sup 3}P) + NH{sub 3} REACTION IN INTERSTELLAR CHEMISTRY. I. INVESTIGATION OF THE PRODUCT FORMATION CHANNELS

Abstract

The product formation channels of ground state carbon atoms, C({sup 3}P), reacting with ammonia, NH{sub 3}, have been investigated using two complementary experiments and electronic structure calculations. Reaction products are detected in a gas flow tube experiment (330 K, 4 Torr) using tunable vacuum-ultraviolet (VUV) photoionization coupled with time of flight mass spectrometry. Temporal profiles of the species formed and photoionization spectra are used to identify primary products of the C + NH{sub 3} reaction. In addition, H-atom formation is monitored by VUV laser induced fluorescence (LIF) from room temperature to 50 K in a supersonic gas flow generated by the Laval nozzle technique. Electronic structure calculations are performed to derive intermediates, transition states, and complexes formed along the reaction coordinate. The combination of photoionization and LIF experiments supported by theoretical calculations indicate that in the temperature and pressure range investigated, the H + H{sub 2}CN production channel represents 100% of the product yield for this reaction. Kinetics measurements of the title reaction down to 50 K and the effect of the new rate constants on interstellar nitrogen hydride abundances using a model of dense interstellar clouds are reported in Paper II.

Authors:
; ;  [1]; ;  [2];  [3]; ;  [4];  [5]
  1. Institut de Physique de Rennes, Astrophysique de Laboratoire, UMR CNRS 6251, Université de Rennes 1, Bât. 11C, Campus de Beaulieu, F-35042 Rennes Cedex (France)
  2. Department of Chemistry, West Virginia University, Morgantown, WV 26506 (United States)
  3. Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, CA 94551 (United States)
  4. Université de Bordeaux, Institut des Sciences Moléculaires, UMR 5255, F-33400 Talence (France)
  5. Univ. Bordeaux, LAB, UMR 5804, F-33270 Floirac (France)
Publication Date:
OSTI Identifier:
22518794
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 812; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; AMMONIA; ATOMS; CARBON; CHEMISTRY; ELECTRONIC STRUCTURE; FAR ULTRAVIOLET RADIATION; FLUORESCENCE; GAS FLOW; GROUND STATES; INTERSTELLAR SPACE; MASS SPECTROSCOPY; MOLECULES; PHOTOIONIZATION; REACTION KINETICS; TEMPERATURE RANGE 0273-0400 K; TIME-OF-FLIGHT METHOD

Citation Formats

Bourgalais, Jérémy, Capron, Michael, Picard, Sébastien D. Le, Kailasanathan, Ranjith Kumar Abhinavam, Goulay, Fabien, Osborn, David L., Hickson, Kevin M., Loison, Jean-Christophe, and Wakelam, Valentine, E-mail: sebastien.lepicard@univ-rennes1.fr, E-mail: fabien.goulay@mail.wvu.edu, E-mail: jean-christophe.loison@u-bordeaux.fr. THE C({sup 3}P) + NH{sub 3} REACTION IN INTERSTELLAR CHEMISTRY. I. INVESTIGATION OF THE PRODUCT FORMATION CHANNELS. United States: N. p., 2015. Web. doi:10.1088/0004-637X/812/2/106.
Bourgalais, Jérémy, Capron, Michael, Picard, Sébastien D. Le, Kailasanathan, Ranjith Kumar Abhinavam, Goulay, Fabien, Osborn, David L., Hickson, Kevin M., Loison, Jean-Christophe, & Wakelam, Valentine, E-mail: sebastien.lepicard@univ-rennes1.fr, E-mail: fabien.goulay@mail.wvu.edu, E-mail: jean-christophe.loison@u-bordeaux.fr. THE C({sup 3}P) + NH{sub 3} REACTION IN INTERSTELLAR CHEMISTRY. I. INVESTIGATION OF THE PRODUCT FORMATION CHANNELS. United States. doi:10.1088/0004-637X/812/2/106.
Bourgalais, Jérémy, Capron, Michael, Picard, Sébastien D. Le, Kailasanathan, Ranjith Kumar Abhinavam, Goulay, Fabien, Osborn, David L., Hickson, Kevin M., Loison, Jean-Christophe, and Wakelam, Valentine, E-mail: sebastien.lepicard@univ-rennes1.fr, E-mail: fabien.goulay@mail.wvu.edu, E-mail: jean-christophe.loison@u-bordeaux.fr. 2015. "THE C({sup 3}P) + NH{sub 3} REACTION IN INTERSTELLAR CHEMISTRY. I. INVESTIGATION OF THE PRODUCT FORMATION CHANNELS". United States. doi:10.1088/0004-637X/812/2/106.
@article{osti_22518794,
title = {THE C({sup 3}P) + NH{sub 3} REACTION IN INTERSTELLAR CHEMISTRY. I. INVESTIGATION OF THE PRODUCT FORMATION CHANNELS},
author = {Bourgalais, Jérémy and Capron, Michael and Picard, Sébastien D. Le and Kailasanathan, Ranjith Kumar Abhinavam and Goulay, Fabien and Osborn, David L. and Hickson, Kevin M. and Loison, Jean-Christophe and Wakelam, Valentine, E-mail: sebastien.lepicard@univ-rennes1.fr, E-mail: fabien.goulay@mail.wvu.edu, E-mail: jean-christophe.loison@u-bordeaux.fr},
abstractNote = {The product formation channels of ground state carbon atoms, C({sup 3}P), reacting with ammonia, NH{sub 3}, have been investigated using two complementary experiments and electronic structure calculations. Reaction products are detected in a gas flow tube experiment (330 K, 4 Torr) using tunable vacuum-ultraviolet (VUV) photoionization coupled with time of flight mass spectrometry. Temporal profiles of the species formed and photoionization spectra are used to identify primary products of the C + NH{sub 3} reaction. In addition, H-atom formation is monitored by VUV laser induced fluorescence (LIF) from room temperature to 50 K in a supersonic gas flow generated by the Laval nozzle technique. Electronic structure calculations are performed to derive intermediates, transition states, and complexes formed along the reaction coordinate. The combination of photoionization and LIF experiments supported by theoretical calculations indicate that in the temperature and pressure range investigated, the H + H{sub 2}CN production channel represents 100% of the product yield for this reaction. Kinetics measurements of the title reaction down to 50 K and the effect of the new rate constants on interstellar nitrogen hydride abundances using a model of dense interstellar clouds are reported in Paper II.},
doi = {10.1088/0004-637X/812/2/106},
journal = {Astrophysical Journal},
number = 2,
volume = 812,
place = {United States},
year = 2015,
month =
}
  • The product formation channels of ground state carbon atoms, C( 3P), reacting with ammonia, NH3, have been investigated using two complementary experiments and electronic structure calculations. Reaction products are detected in a gas flow tube experiment (330 K, 4 Torr) using tunable vacuum-ultraviolet (VUV) photoionization coupled with time of flight mass spectrometry. Temporal profiles of the species formed and photoionization spectra are used to identify primary products of the C + NH 3 reaction. In addition, H-atom formation is monitored by VUV laser induced fluorescence (LIF) from room temperature to 50 K in a supersonic gas flow generated by themore » Laval nozzle technique. Electronic structure calculations are performed to derive intermediates, transition states, and complexes formed along the reaction coordinate. The combination of photoionization and LIF experiments supported by theoretical calculations indicate that in the temperature and pressure range investigated, the H + H 2CN production channel represents 100% of the product yield for this reaction. As a result, kinetics measurements of the title reaction down to 50 K and the effect of the new rate constants on interstellar nitrogen hydride abundances using a model of dense interstellar clouds are reported in Paper II.« less
  • A continuous supersonic flow reactor has been used to measure rate constants for the C({sup 3}P) + NH{sub 3} reaction over the temperature range 50–296 K. C({sup 3}P) atoms were created by the pulsed laser photolysis of CBr{sub 4}. The kinetics of the title reaction were followed directly by vacuum ultra-violet laser induced fluorescence of C({sup 3}P) loss and through H({sup 2}S) formation. The experiments show unambiguously that the reaction is rapid at 296 K, becoming faster at lower temperatures, reaching a value of (1.8 ± 0.2) × 10{sup −10} cm{sup 3} molecule{sup −1} s{sup −1} at 50 K. Asmore » this reaction is not currently included in astrochemical networks, its influence on interstellar nitrogen hydride abundances is tested through a dense cloud model including gas–grain interactions. In particular, the effect of the ortho-to-para ratio of H{sub 2}, which plays a crucial role in interstellar NH{sub 3} synthesis, is examined.« less
  • There may be a region in the potential-energy surface (PES) a reaction forbidden by symmetry in the ground electronic state but occurring with inversion of the filled and vacant MO of the reagent and product in which the corresponding solutions obtained in the restricted Hartree-Fock approximation are singlet-unstable. There are then singlet-stable solutions with lower energies, but which correspond to configurations of lower symmetry. As a result, the PES may have reaction channels of reduced symmetry. An example is considered of the cyclization of a linear D/sub infinity h/ structure for CO/sub 2/ to the C/sub 2V/ structure forbidden bymore » symmetry for the ground electronic state. MINDO/3 calculations show that a curve with two wells applies for the region in the PES of the ground singlet state for which the RHF solutions are singlet-unstable, where the section of the minimum-energy path along the distortion coordinate leads to a geometrical configuration of lower symmetry, i.e., there are two degenerate reaction channels in this region of the PES, which correspond to geometrical configurations of symmetry C/sub 1/.« less
  • The authors have measured the rate constant for the reactions BrO + ClO ..-->.. Br + OClO (6a), BrO + ClO ..-->.. Br + Cl + O/sub 2/ (6b), and BrO + ClO ..-->.. BrCl + O/sub 2/ (6c) over the temperature range 241-408 K and found k/sub 6/ = (8.2 +/- 1.0) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/ independent of temperature. Measurement of the individual product branching ratios yielded values for channels 6a, 6b, and 6c equal to 0.55 +/- 0.10, 0.45 +/- 0.10, and < 0.02, respectively. Measurements of ozone in the stratosphere over Antarcticamore » have shown that the springtime ozone column has fallen 40% from 1960 to 1985. The reaction above could account for a large fraction of the springtime ozone hole reported recently, provided that at least 20 ppt of total inorganic bromine is present, and it may provide a source of chlorine dioxide of sufficient magnitude to explain the recent measurements of this species in the Antarctica stratosphere.« less
  • No abstract prepared.