Effect of particle size on laser-induced breakdown spectroscopy analysis of alumina suspension in liquids

The analysis by Laser Induced Breakdown Spectroscopy (LIBS) was proposed for the detection and the quantification of different elements in water even when the analyte is composed of particles in suspension.We have studied the effect of particle size on the LIBS signal during liquid analysis. In our study we used different particle sizes (from 2 μm to 90 μm) of Al2O3 in suspension in water. The results were compared to the signal obtained in the case of dissolved aluminum.In the case of particles, a linear correlation between the LIBS signal versus concentration was found but a significant decrease in the slope of the calibration curve was found when the particle size increased. Several hypotheses have been tested and only a partial ablation of the particles might explain this decrease in signal intensity. This effect probably does not occur at smaller particle size. We estimated 860 nm/pulse as ablated thickness from the top of the particle. A statistical analysis over all data obtained allowed us to calculate 100 μm as ablated water column depth.

► We have identified a decrease of calibration curve when particle size increases.
► Partial particle ablation has been identified as the origin of this effect.
► The ablation rate on Al2O3 particles in suspension in water has been estimated.
► We can determine the deepness of the interaction volume into the liquid.