Angular distributions of C-2 and CN formed by laser ablation of graphite in a nitrogen atmosphere

Optical time-of-flight measurements have been performed to obtain snapshots of spatial distributions of C-2 and CN molecules produced by laser ablatio n of graphite in a nitrogen atmosphere. The propagation direction of C2 was Oriented along the target surface normal regardless of the nitrogen pressu re while that of CN was inclined towards the incident laser beam at low nit rogen pressures. This anomalous propagation of CN molecules is attributed t o the high activation energy of the reaction C-2 + N-2 --> 2CN, which is fa cilitated in a hot region generated by laser-plume interaction. (C) 2001 El sevier Science B.V. All rights reserved.