CH + H 2 : extracting the maximum rate coefficient information Mark A Blitz 1 , Lavinia Onel 1 , Struan H Robertson 2 and Paul W Seakins 1 1 School of Chemistry, University of Leeds, UK, 2 Dassault Systemes, Cambridge, UK Many reactions have multiple product channels and this is even the case for the simplest of reactions when studied over a wide temperature range. In general, experiments are arranged to measure each channel via its kinetics. However, determining the kinetics of some channels is much easier than others, especially if one of the channels is a radical-radical reaction, where the radical concentration needs to be assigned. Reaction rate theory does not have this problem and is able to assign all the rate coefficients of the system, but its calculated rate coefficients are only accurate if the potential energy surface (the crucial parameter of the system) is also accurate. If the crucial parameters of reaction rate theory can be adjusted to match experiments for the components of the system that are well-determined, then it should be possible to more confidently assign all the rate coefficients of a given system. In this study, the literature experimental data on the reaction CH + H 2 reaction is modelled using reaction rate theory, using MESMER [1] which has parameter fitting built into it. The reaction has multiple channels: CH + H 2 → CH 3 k 1a CH + H 2 → CH 2 + H k 1b Experimentally, there is an extensive dataset on k 1a [2-4] and from shock tube studies there are CH 3 decomposition data, [5] k -1a and CH 3 → CH 2 + H. However, the literature data on k -1b , CH 2 + H, [6,7] is variable, presumably as [H] needs to be determined, H generally being the radical in excess. In this work, it is shown that MESMER is able to fit the CH removal kinetics and shock tube CH 3 decomposition data. This fitting result provides a better defined value for k -1b ( T ) and also highlights problems in the shock tube kinetic assignment on CH 3 → CH 2 + H. References 1. D.R. Glowacki, C.H. Liang, C. Morley, M.J. Pilling, S.H. Robertson, J. Phys. Chem. A 116 (2012) 9545. 2. A. McIlroy, F.P. Tully, J. Chem. Phys. 99 (1993) 3597. 3. R.A. Brownsword, L.B. Herbert, I.W.M. Smith, D.W.A. Stewart, Journal of the Chemical Society-Faraday Transactions 92 (1996) 1087. 4. D. Fulle, H. Hippler, J. Chem. Phys. 106 (1997) 8691. 5. V. Vasudevan, R.K. Hanson, D.M. Golden, C.T. Bowman, D.F. Davidson, J. Phys. Chem. A 111 (2007) 4062. 6. K. Devriendt, M. Vanpoppel, W. Boullart, J. Peeters, J. Phys. Chem. 99 (1995) 16953. 7. M. Rohrig, E.L. Petersen, D.F. Davidson, R.K. Hanson, C.T. Bowman, Int. J. Chem. Kinet. 29 (1997) 781.
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