Wavelength dependant ablation rates for metals and silicate glasses using homogenized laser beam profiles — implications for LA-ICP-MS

Laser ablation (LA) inductively coupled plasma mass spectrometry (ICP-MS) is a versatile micro-analytical technique for the determination of major, minor and trace elements in solid materials. Recent interest has concentrated on using the technique for layer analysis or depth profiling. However, little data has been published on the rates of ablation which provide essential information for determining depth resolution. Knowledge of the ablation rates is essential for the selection of optimum laser parameters for different target materials. It also provides estimates of uncertainties for quantification on materials where no internal standard is available to correct for differences in ablation volume. This work presents results on the ablation rates of metals (such as Al, Cu, Ni, Ti, Mo, Pt, Zn, Cr and Si), the SRM NIST 600 series glasses and natural calcium fluoride for laser fluencies between 3.5 and 35 J/cm2 using argon or helium as ablation environment together with two fundamentally different types of lasers (193 nm Excimer and 266 nm Nd:YAG).