Computer simulations of laser ablation sample introduction for plasma-source elemental microanalysis

Elemental microanalysis, using laser ablation for sample introduction into plasma-source spectrometry, is based on the analytical information carried by the ablated particles that are delivered to the ICP. Numerical. uid- dynamical simulations allowed us to understand the flow characteristics of the carrier gas, which in. uence the sample introduction and signal intensity. The carrier gas. ow in the transport tubing was found to be laminar, with nested velocity paraboloids, whose front pro. le is less sharp for heavier carrier gases. The gas velocity is also characterized by high- frequency. uctuations along the tube length due to molecular di. usion. The temporal signal pro. les were modelled considering the aerosol. lling and elution rates in the setup, the whole setup dimensions, the transport e. ciency, and the particle sizes, combined with a condition of mass conservation. The simulated signal intensity showed a logarithmic dependence on the transport efficiency, which exacerbates signal structure. Finally, in passing from single shot to repeated shot analysis, the transient signals were modelled calculating the convolution of the single shot pro. le with the laser pulse sequence pro. le.