DEPTH-RESOLVED ANALYSIS OF MULTILAYERED SAMPLES BY LASER-INDUCED BREAKDOWN SPECTROMETRY

The capability of laser-induced breakdown spectrometry (LIES) to resol ve complex depth profiles is demonstrated. Electrolytically deposited brass samples were analyzed by monitoring the emission corresponding t o Cr (357.8 nm), Ni (341.4 nm), Cu (327.4 nm) and Zn (334.5 nm). The n ominal thickness of the layers was known, which permitted an estimate of the ablated mass in the range between 150 and 500 nm per pulse depe nding on the matrix and laser irradiance. Laser irradiance was varied by defocusing, and its effect on the depth-resolution of LIES was test ed For comparison purposes, a commercial zinc-coated steel was also st udied by following the Zn and Fe emission intensity depth profiles wit h a commercial glow-discharge optical emission spectrometry system to obtain information on the exact location of the Zn-Fe interface (12 mu m). The ablation rate in terms of ablated mass per pulse was found to be at the ng per pulse level and depended on the laser pulse irradian ce.