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Astron. Astrophys. 323, 644-651 (1997)

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Reactions of the methylidine radical with [FORMULA], [FORMULA] [FORMULA], [FORMULA] [FORMULA], [FORMULA] [FORMULA], and but-1-ene studied between 23 and 295 K with a CRESU apparatus

A. Canosa 1, I.R. Sims 2, D. Travers 1, I.W.M. Smith 2 and B.R. Rowe 1

1 Université de Rennes I, "Physique des Atomes, Laser, Molécules et Surfaces", UMR 6627 du C.N.R.S., Equipe: "Astrochimie Expérimantale", Campus de Beaulieu, F-35042 Rennes Cedex, France (canosa@univ-rennes1.fr)
2 School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

Received 15 July 1996 / Accepted 19 September 1996

Abstract

The temperature dependences of the reactions of the methylidine radical (CH) with several hydrocarbons were studied in the temperature range 23-295 K using the Rennes CRESU apparatus coupled with the pulsed laser photolysis (PLP), laser induced fluorescence (LIF) technique. All the reactions remain very fast at low temperature. For the reactions of CH with olefins, a maximum rate is obtained at about 70 K and then the rate coefficients slightly decrease at lower temperatures. A similar effect is observed in the data for CH+CH4 and CH+C2 H6 with a maximum rate being obtained at about 40 K. The results are compared with previous studies where available, and the nature of the possible products is also discussed, although this study does not enable their detection. Consequences of these new results for the chemistry of planetary atmospheres and interstellar clouds are stressed.

Key words: molecular data – molecular processes – methods: laboratory – ISM: molecules – planets: atmospheres – rate constant

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© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998

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