Multielemental chemical imaging using laser-induced breakdown spectrometry

Multichannel laser-induced breakdown spectrometry (LIES) is used to generate selective chemical images for sih er, titanium, and carbon from silicon photovoltaic cells, A 2.5 mi pulsed nitrogen laser and a spectrometer using charge-coupled device detection were employed. LIBS images were acquired sequentially by moving the sample located on a motorized x-y translational stage step by step while storing the multichannel LIES spectrum for each position of the sample, followed by computer-based reconstruction of two-dimensional selective images from intensity profiles at several wave lengths, Depth distributions of carbon impurities are also reported, Room temperature and atmospheric pressure operation as used here remove the restrictions on sample size exhibited by other surface analysis techniques used for imaging applications, Thus, the sample size in LIES imaging is in principle unlimited. A LIES experiment does not require a sample to be conductive. Therefore, virtually all materials can be imaged, Although LIES is a typical example of destructive analytical technique, multichannel detection as demonstrated here confers the possibility to LIES of obtaining multielement information from a given surface area, Lateral resolution of 80 mu m and depth resolution of better than 13 nm were observed, The ultimate limitation to imaging the first layer of the surface in LIES is the spectral signal-to-noise ratio as dictated by the ablation threshold of the material.