A. Canosa et al., REACTIONS OF THE METHYLIDINE RADICAL WITH CH4, C(2)H(2)R C2H4, C2H6, AND BUT-1-ENE STUDIED BETWEEN 23-K AND 295-K WITH A CRESU APPARATUS, Astronomy and astrophysics, 323(2), 1997, pp. 644-651
The temperature dependences of the reactions of the methylidine radica
l (CH) with several hydrocarbons were studied in the temperature range
23-295 K using the Rennes CRESU apparatus coupled with the pulsed las
er photolysis (PLP), laser induced fluorescence (LIF) technique. All t
he 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 th
e fate coefficients slightly decrease at lower temperatures, A similar
effect is observed in the data for CH+CH4 and CH+C2H6 with a maximum
rate being obtained at about 40 K. The results are compared with previ
ous studies where available, and the nature of the possible products i
s also discussed, although this study does not enable their detection.
Consequences of these new results for the chemistry of planetary atmo
spheres and interstellar clouds are stressed.