Rare-earth elements detection using diatomic molecular laser-induced plasma spectroscopy

Abstract

The detection of Rare-Earth-Elements by LIBS by their atomic and ionic emission in many cases is difficult due to significant spectral interferences from other members of this group and accompanying elements. Another potential detection mode is to use molecular emission. It was previously considered that only La, Y, and Sc form analytically useful molecules in Laser-Induced Plasma. We proved that the molecules of other rare-earth elements (Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y, and Lu) with oxygen appear effective for analytical purposes. The type of the emission spectrum depends on specific element molecular weight and differs for Light and Heavy REE sub-groups. This approach is demonstrated for Gd analysis in ceria (CeO2) and in permanent B-Fe-Nd and Sm-Co-Ni magnets. The presence of molecular emission of Rare-Earth-Elements opens an opportunity to apply Laser Ablation Molecular Isotopic Spectrometry and Molecular Laser-Induced Fluorescence - LIBS combination for their isotopes analysis.