TIME-RESOLVED PARAMETRIC STUDIES OF LASER-ABLATION USING INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROSCOPY

The quantity of ablated mass and its composition strongly depend on th e number of laser pulses and laser fluence at the sample target surfac e. For chemical analysis, thin-film deposition,cutting, and other lase r-ablation applications, the quantity of mass removed vs. number of la ser pulses is important. In addition, the composition of the vapor can be critical, for example, in providing accurate chemical analysis or well-defined thin film structures. In this work, mass ablation rate an d ablated mass composition were studied by monitoring the time depende nce of emission intensity using Inductively Coupled Plasma Atomic Emis sion Spectroscopy (ICP) during repetitive laser ablation at a single l ocation on the sample target. Spectral emission intensity in the ICP i s directly related to the quantity of mass ablated by the laser. The r atio of spectral emission lines in the ICP gives an indication of the relative composition of ablated constituents. In this work, a brass sa mple was ablated using several lasers with various properties. Emissio n intensities of Cu and Zn ionic lines, after the occurrence of an ini tial signal spike, increase with increasing number of laser pulses at high fluence, whereas at low fluence no significant changes were obser ved in the mass ablation rate. The zinc-to-copper ratio was used to mo nitor fractionation processes during repetitive laser ablation. The ra tio increased with increasing ablation time at low fluence. In contras t, the ratio was almost constant, and close to the accurate level at h igh laser fluences. The effect of various laser parameters on the mass ablation rate and mass composition are discussed in this paper. Publi shed by Elsevier Science B.V.