Laser-induced optical emission of carbon plume by excimer and Nd:YAG laser irradiation

We investigated the effect of additional laser irradiation on the energy state of a laser-ablated plume from a graphite target. Optical emissions from the plume were observed by a spectrometer equipped with an intensified charged couple device (ICCD) immediately after additional laser irradiation at various time delays relative to the ablation. The emission intensity from atomic carbon, ionic carbon, C2 and C3 increased when an ArF excimer laser irradiated the carbon plume. The atomic carbon absorbed the ArF excimer laser resonantly and was ionized. Using the fourth harmonic output of an Nd:YAG laser or a KrF excimer laser, the emission intensity from C2 and C3 only increased. However, no emission spectra change was observed with additional irradiation fundamental output of an Nd:YAG laser. The emission intensity from the atomic and ionic carbon and carbon clusters (C2 and C3) following ArF excimer laser irradiation of the plume was stronger than that using any other lasers.