ONSET OF CARBON CLUSTER FORMATION INFERRED FROM LIGHT-EMISSION IN A LASER-INDUCED EXPANSION

Space-time analysis of the light emitted from C, C2, and C3 has been performed in a laser-evaporated carbon expansion. The measured propagation velocities and concentration evolutions display the aggregation process as a half collision governed by momentum conservation. C2 and C3 clusters are produced with strong electron excitation, the energy excess of which is removed by photon emission instead of collisional cooling.