Calibration free laser-induced breakdown spectroscopy of oxide materials

a r t i c l e i n f o Keywords: Calibration free laser-induced breakdown spectroscopy (CF-LIBS) Multi-element analysis Oxides The quantitative determination of oxide concentration by laser-induced breakdown spectroscopy is relevant in various fields of applications (e.g.: analysis of ores, concrete, slag). Calibration free laser-induced breakdown spectroscopy and the multivariate calibration are among the methods employed for quantitative concentration analysis of complex materials. We measured the intensity of neutral and ionized atomic emission lines of oxide materials by laser-induced breakdown spectroscopy and we modified the calibration free laser-induced breakdown spectroscopy method to increase the accuracy. The concentration of oxides was obtained by using stoichiometric relations. Sample materials were prepared from oxide powder (Fe 2 O 3 , MgO, CaO) by mixing and pressing. The concentration was 9.8–33.3 wt.% Fe 2 O 3 , 7.6–33.3 wt.% MgO and 33.3–81.2 wt.% CaO for different samples. Nd:YAG laser (wavelength 1064 nm, pulse duration ≈ 6 ns) ablation was performed in air. The laser-induced plasma emission was measured by an Echelle spectrometer equipped with a sensitivity calibrated ICCD camera. The numerical calibration free laser-induced breakdown spectroscopy algorithm included the fast deconvolution of instrumental function, and the correction of self-absorption effects. The oxide concentration C CF calculated from calibration free laser-induced breakdown spectroscopy results and the nominal concentration C N were very close for all samples investigated. The relative error in concentration, |C CF –C N |/C N , was b 10%, b 20%, and b 5% for Fe 2 O 3 , MgO, and CaO, respectively. The results indicate that this method can be employed for the analysis of major elements in multi-component technical materials. Laser-induced breakdown spectroscopy (LIBS) is a versatile method for fast and accurate multi-element analysis of gaseous, liquid and solid samples [1,2]. Commonly, univariate or multivariate regression models are employed for quantitative analysis using calibration samples and standards [3–5]. Drawbacks of this approach are the need of calibration samples and/or standards with same matrices as the samples under investigations and the necessity of constant experimental parameters (e.g. laser energy, spot diameter). An alternative method for quantitative analysis without the need of calibration samples is calibration-free LIBS (CF-LIBS) [6]. The CF-LIBS method (or variants of it) have been used for calibration free analysis of various materials such as copper alloys [7–9], aluminium alloys matrices the CF-LIBS method is often only semi-quantitative because of effects like radiation self-absorption and the …