Abstract
Lifetimes and relative intensities of the C2 (d-a) Swan bands have been remeasured using the High Frequency Deflection technique, yielding τ(d, ν = 0-6) = 120 ± 4 ns. With increasing pressure of the C2H2 target gas strong second lifetime components occur revealing collisional transfers from other C2 levels with rate coefficients around 6 × 10-11 cm3 s-1 mol-1. These transfers are also observed with a number of other catalyser gases such as He, Ne, Ar, N2, and CO2. The transfer processes explain the considerably longer lifetimes reported in several earlier life-time investigations and could be a clue to the formation mechanism of the carbon high pressure bands.

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