Quantitative analysis of the element iron in aluminum alloy using LIBS

In order to precisely analyze electron temperature and electron density of aluminum alloy, the Laser Induced Breakdown Spectroscopy was adopted. The second harmonic of a pulsed Nd:YAG laser (532 nm) has been used for the ablation of aluminum alloy E311 in air at atmospheric pressure and the laser-induced plasma characteristics were examined in detail. The electron density of 4.31016 cm-3 was inferred from the Stark broadening (0.12 nm) of the profile of Fe (I) 381.59 nm. In order to minimize relative errors in calculation of the electron temperature, an improved iterative Boltzmann plot method with eight iron lines (370.56, 386.55, 387.25, 426.05, 427.18, 430.79, 432.57, 440.48 nm) is used. Experimental results show that the electron temperature is 8 699 K with the regression coefficient of 0.999. The calibration curve for iron based on Fe (I) 404.58 nm was established using a set of six samples of standard aluminum alloy (E311, E312, E313, E314, E315, E316) and the detection limit was 0.077 9 wt%. The plasma was verified to be optically thin and in local thermodynamic equilibrium based on the experimental results.