The gas-phase chemistry of carbon chains in dark cloud chemical models

Jean-Christophe Loison 1 Valentine Wakelam 2 Kevin M. Hickson 1 Astrid Bergeat 1 Raphael Mereau
2 AMOR 2013
L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux, OASU - Observatoire aquitain des sciences de l'univers, LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac], Université Sciences et Technologies - Bordeaux 1
Abstract : We review the reactions between carbon chain molecules and radicals, namely Cn, CnH, CnH2, C2n+1O, CnN, HC2n+1N, with C, N and O atoms. Rate constants and branching ratios for these processes have been re-evaluated using experimental and theoretical literature data. In total 8 new species have been introduced, 41 new reactions have been proposed and 122 rate coefficients from kida.uva.2011 (Wakelam et al. 2012) have been modified. We test the effect of the new rate constants and branching ratios on the predictions of gas-grain chemical models for dark cloud conditions using two different C/O elemental ratios. We show that the new rate constants produce large differences in the predicted abundances of carbon chains since the formation of long chains is less effective. The general agreement between the model predictions and observed abundances in the dark cloud TMC-1 (CP) is improved by the new network and we find that C/O ratios of 0.7 and 0.95 both produce a similar agreement for different times. The general agreement for L134N (N) is not significantly changed. The current work specifically highlights the importance of O + CnH and N + CnH reactions. As there are very few experimental or theoretical data for the rate constants of these reactions we highlight the need for experimental studies of the O + CnH and N + CnH reactions, particularly at low temperature.
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Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2013, 437 (1), pp.930-945. 〈10.1093/mnras/stt1956〉
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Soumis le : lundi 18 novembre 2013 - 13:46:49
Dernière modification le : mercredi 27 juillet 2016 - 14:48:48

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Jean-Christophe Loison, Valentine Wakelam, Kevin M. Hickson, Astrid Bergeat, Raphael Mereau. The gas-phase chemistry of carbon chains in dark cloud chemical models. Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2013, 437 (1), pp.930-945. 〈10.1093/mnras/stt1956〉. 〈hal-00905547〉

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