Surface interaction and chemical imaging in plasma spectrometry induced with a line-focused laser beam

An experimental line imaging arrangement for surface characterization of solid samples in air at atmospheric pressure using laser-induced plasma spectrometry (LIPS) is presented. A microline plasma was formed by focusing a Nd:YAG laser beam operating at 532 nm with a cylindrical lens on the sample surface. The spatial resolution was investigated as a function of beam focal parameters including cylindrical lens focal length, beam diameter and pulse energy. While focal length affected lateral resolution only slightly, a strong dependence of crater width on beam diameter and laser pulse energy was observed. For routine sample imaging the crater width obtained was close to 15 μm while the spatial resolution along the spectrometer slit was 17.4 μm. Compositional distribution maps of inclusion constituents (Mg, Ca, Si, Al and Ti) in stainless steel are shown. The results demonstrate the potential of microline imaging for fast analysis of large area samples and for screening purposes.