Origin of C2 high-pressure bands observed in the products of a microwave discharge through CO
✍ Scribed by P. Caubet; G. Dorthe
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 659 KB
- Volume
- 218
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
The origin of C2 high-pressure bands observed in discharges through CO has not been cleared up. The suggestion by Little and Browne of a collisional transfer between the metastable CI('l&, u=O) and the radiative Cz(d 3TI,, ~6) level was progress. However, these authors claimed that only the combination reaction C + C + M-K* + M should be invoked for the production of the metastable level, excluding the C + C20+ C2 + CO reaction that other authors believed to be at the origin of the Cz HP bands. The correlation diagram of the C + C20-+Cz + CO reaction shows that C,( SIIr) + CO correlates with ground-state reactants while Cr (d 311s) + CO does not. Such a reaction could thus be involved in the C2 HP bands. A kinetic study of these bands in a fastflow reactor, downstream from a microwave discharge through CO diluted in He, demonstrated that both reactions C+C+M and C + C20 were involved. It could be concluded that the C + C,O-C,+ CO reaction has a lower branching ratio for C,( 'IT,) production than C + C + M+ C2 + M. However, the C + CzO reaction has in most discharges, as in ours, a greater reaction rate than that of the C + C + M reaction so its contribution is not negligible and may be the main one if the dissociation rate of CO is low.