Application of Laser Induced Plasma Spectroscopy to the Analysis of Rock Samples†

Laser induced plasma spectroscopy has been applied to the analysis of element distribution mapping of polished rock sections. The plasma was generated by focusing a frequency-doubled second harmonic 532 nm Nd:YAG laser on the target under atmospheric conditions. The experimental parameters, such as laser energy, atomic emission line and time profile of the plasma spectrum, were characterized to obtain optimum experimental conditions and estimate the element composition of the target surface. For the element mapping of samples, an X–Y stage was used to move the sample and an element image of 50 × 50 mm could be made in 30 min. Using this technique, the element concentration distribution of Ba, Cu, Fe, Mn, Pb, Si and Sr in polished rock sections were obtained. Quantitative analysis was achieved by analyzing standard rock samples. Calibrated concentration versus plasma intensity was used for the color grading for the mapping of element concentration distribution.