Optical emission spectroscopy studies of the influence of laser ablated mass on dry inductively coupled plasma conditions

The amount of ablated mass can influence the temperature and excitation characteristics of the inductively coupled plasma (ICP) and must be taken into account to ensure accurate chemical analysis. The ICP electron number density was investigated by using measurements of the Mg ionic to atomic resonant-line ratios during laser ablation of an aluminum matrix. The ICP excitation temperature was measured by using selected Fe lines during laser ablation of an iron matrix. A Nd:YAG laser (3 ns pulse duration) at 266 nm was used for these ablation-sampling studies. Laser energy, power density, and repetition rate were varied in order to change the quantity of ablated mass into the ICP. Over the range of laser operating conditions studied herein, the ICP was not significantly influenced by the quantity of solid sample. Therefore, analytical measurements can be performed accurately and fundamental studies of laser ablation processes (such as ablation mass roll-off, fractional vaporization) can be investigated using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). (C) 1998 Elsevier Science B.V.