A unique technique of laser-induced breakdown spectroscopy using transversely excited atmospheric CO 2 laser for the sensitive analysis of powder samples

Abstract

A sensitive analysis of powder samples has successfully been conducted using a strong gas breakdown plasma induced by assisting a metal mesh and a metal subtarget utilizing a transversely excited atmospheric (TEA) CO 2 laser; the metal mesh and the metal subtarget were placed on the front side and backside of the sample, respectively. The experiment was made at high pressure of air surrounding gas. In this study, the TEA CO 2 laser (1.5 J, 200 ns) was focused on the sample surface through the metal mesh. At the initial stage, a strong gas breakdown plasma was initiated by the assist of the metal mesh and finally enhanced by the metal subtarget after the laser beam struck on the metal subtarget’s surface through a hole inside the sample. The strong gas breakdown plasma can effectively be applied to completely dissociate and excite the ablated atoms from the sample. Using this technique, an excellent calibration curve with zero intercept has been made using herb medicine powder sample containing different concentrations of Zn. For sensitive analysis, a detection of hazard element of Cr in commercial supplement was also carried out. The detection limit of Cr was estimated to be around 0.6 mg/kg. This present technique has high possibility to realize the analysis of powder samples with high precision and high sensitivity.