LABORATORI NAZIONALI DI LEGNARO
In a recent study we investigated the mechanisms that determine the distribution of laser energy between a metallic target and its plasma during ns-laser ablation. A typical experimental situation, encountered in chemical analysis techniques such as Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), was investigated. In our study, a copper sample is placed in an inert background gas and irradiated by a 6 ns Nd:YAG laser pulse operating at fluences up to 15 J/cm². A hybrid multiphase model describes the transient behaviour in and above the copper target. A set of rate equations is used for the study of ns-laser induced breakdown, whereas a hydrodynamic LTE model is employed for the subsequent expansion stage of the plasma. Contrary to earlier findings reported in the literature, it is demonstrated that under the present conditions, photo processes as well as volumetric ablation mechanisms play a predominant role in the onset of ns-laser induced plasma formation.

DATA: 31-01-2014