On the enhancement of laser induced breakdown spectroscopy signal in double pulse configuration

摘要

Laser Induced Breakdown Spectroscopy (LIBS) performed in double pulse (DP) configuration is a promising development of the traditional well-known LIBS, which makes use of a single laser pulse for the ablation of the sample. In the DP configuration a pair of pulses, delayed the one with respect to the other by a temporal gap of the order of 1-10 μs, is used for the ablation of material from the target surface and consequent formation of a plasma plume; depending on the experimental conditions, large enhancements of the resulting LIBS signal can be obtained. In this paper, the main physical mechanisms underlying double-pulse LIBS measurements are discussed, in order to obtain a deeper insight of the effects resulting in the signal enhancement obtained in DP-LIBS with respect to single pulse LIBS. The effect of laser energy, buffer gas type and density is discussed. A model of DP LIBS is proposed in terms of the Sedov strong explosion theory.