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Zeitschrift für Physikalische Chemie

International journal of research in physical chemistry and chemical physics

Ed. by Rademann, Klaus

12 Issues per year


IMPACT FACTOR 2016: 1.012

CiteScore 2016: 0.99

SCImago Journal Rank (SJR) 2016: 0.463
Source Normalized Impact per Paper (SNIP) 2016: 0.470

Online
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2196-7156
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Volume 229, Issue 10-12 (Oct 2015)

Issues

The Kinetics of the Reaction C2H5 + HI → C2H6 + I over an Extended Temperature Range (213–623 K): Experiment and Modeling

Nicholas Leplat
  • Laboratory of Atmospheric Chemistry (LAC), Paul Scherrer Institute (PSI), CH-5232 Villigen PSI, Switzerland
  • Present address: Melbourne School of Engineering, Mechanical Engineering, Engineering Block E Bldg., The University of Melbourne, Parkville 3010 VIC, Australia
  • Other articles by this author:
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/ Jozef Federič
  • Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Mlynskádolina CH1, 84215, Bratislava, Slovakia
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/ Katarína Šulková
  • Advanced Technologies Research Institute, Faculty of Materials Science and Technology, Slovak University of Technology in Bratislava, Hajdóczyho 1, 917 24 Trnava, Slovakia
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/ Mária Sudolská
  • Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Mlynskádolina CH1, 84215, Bratislava, Slovakia
  • Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University Olomouc, 17, listopadu 12, 771 46 Olomouc, Czech Republic
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/ Florent Louis
  • PhysicoChimie des Processus de Combustion et de l'Atmosphère (PC2A), UMR 8522 CNRS/Lille1, Université Lille 1 Sciences et Technologies, Cité Scientifique, Bât. C11/C5, 59655 Villeneuve d'Ascq Cedex, France
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/ Ivan Černušák
  • Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Mlynskádolina CH1, 84215, Bratislava, Slovakia
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/ Michel Jean Rossi
  • Corresponding author
  • Laboratory of Atmospheric Chemistry (LAC), Paul Scherrer Institute (PSI), CH-5232 Villigen PSI, Switzerland
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Published Online: 2015-09-11 | DOI: https://doi.org/10.1515/zpch-2015-0607

Abstract

The present study reports temperature dependent rate constants k1 for the title reaction across the temperature range 213 to 293 K obtained in a Knudsen flow reactor equipped with an external free radical source based on the reaction C2H5I + H → C2H5 + HI and single VUV-photon ionization mass spectrometry using Lyman-α radiation of 10.2 eV. Combined with previously obtained high-temperature data of k1 in the range 298–623 K using the identical experimental equipment and based on the kinetics of C2H5 disappearance with increasing HI concentration we arrive at the following temperature dependence best described by a three-parameter fit to the combined data set: k1 = (1.89 ± 1.19)10−13(T/298)2.92±0.51 exp ((3570 ± 1500)/RT), R = 8.314 J mol1 K1 in the range 213–623 K. The present results confirm the general properties of kinetic data obtained either in static or Knudsen flow reactors and do nothing to reconcile the significant body of data obtained in laminar flow reactors using photolytic free radical generation and suitable free radical precursors. The resulting rate constant for wall-catalyzed disappearance of ethyl radical across the full temperature range is discussed.

Highly correlated ab initio quantum chemistry methods and canonical transition state theory were applied for the reaction energy profiles and rate constants. Geometry optimizations of reactants, products, molecular complexes, and transition states are determined at the CCSD/cc-pVDZ level of theory. Subsequent single-point energy calculations employed the DK-CCSD(T)/ANO-RCC level. Further improvement of electronic energies has been achieved by applying spin-orbit coupling corrections towards full configuration interaction and hindered rotation analysis of vibrational contributions. The resulting theoretical rate constants in the temperature range 213–623 K lie in the range E-11–E-12 cm3 molecule1 s1, however experiments and theoretical modelling seem at great odds with each other.

This article offers supplementary material which is provided at the end of the article.

Keywords: Ethyl Free Radical; H-Metathesis; Reaction Rate Constant; Temperature Dependence; Arrhenius Rate Parameters; ab initio Calculations; Potential Energy Surface; Spin-Orbit Interaction

Supplementary material

the online version of this article (DOI: 10.1515/zpch-2015-0607) provides supplementary material for authorized users.

About the article

Accepted: 2015-08-15

Received: 2015-03-30

Published Online: 2015-09-11

Published in Print: 2015-10-28


Citation Information: Zeitschrift für Physikalische Chemie, ISSN (Online) 2196-7156, ISSN (Print) 0942-9352, DOI: https://doi.org/10.1515/zpch-2015-0607.

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