We observed continuum optical emission from carbon plumes produced by laser ablation of a graphite target. Two types of continuum emission were observed: a spiky emission just after the irradiation of the laser pulse and a delayed component observed in ambient He gas. It was shown by optical emission imaging spectroscopy and laser-induced fluorescence (LIF) imaging spectroscopy that the delayed continuum emission grew in the region where the loss of C-2 was significant. This result suggests that the delayed continuum emission is originated from clustering reactions among carbon species in the plume. (C) 2002 Elsevier Science B.V All rights reserved.