MULTIELEMENTAL CHEMICAL IMAGING USING LASER-INDUCED BREAKDOWN SPECTROMETRY

Multichannel laser-induced breakdown spectrometry (LIES) is used to ge nerate selective chemical images for sih er, titanium, and carbon from silicon photovoltaic cells, A 2.5 mi pulsed nitrogen laser and a spec trometer using charge-coupled device detection were employed. LIBS ima ges were acquired sequentially by moving the sample located on a motor ized x-y translational stage step by step while storing the multichann el LIES spectrum for each position of the sample, followed by computer -based reconstruction of two-dimensional selective images from intensi ty profiles at several wave lengths, Depth distributions of carbon imp urities are also reported, Room temperature and atmospheric pressure o peration as used here remove the restrictions on sample size exhibited by other surface analysis techniques used for imaging applications, T hus, the sample size in LIES imaging is in principle unlimited. A LIES experiment does not require a sample to be conductive. Therefore, vir tually all materials can be imaged, Although LIES is a typical example of destructive analytical technique, multichannel detection as demons trated here confers the possibility to LIES of obtaining multielement information from a given surface area, Lateral resolution of 80 mu m a nd depth resolution of better than 13 nm were observed, The ultimate l imitation to imaging the first layer of the surface in LIES is the spe ctral signal-to-noise ratio as dictated by the ablation threshold of t he material.