Double-pulse laser-induced breakdown spectroscopy for trace element analysis in sintered iron oxide ceramics

Double-pulse laser-induced breakdown spectroscopy (LIBS) is an emerging technique for accurate compositional analysis of many different materials. We present a systematic study of collinear double-pulse LIBS for analysis of the trace and side elements boron, manganese, copper, aluminum, titanium, silicon, chromium, nickel, potassium, and calcium in sintered iron oxide targets. The samples were ablated in air by single-pulse and double-pulse Nd:YAG laser radiation (6 ns pulse duration, laser wavelength of 532 nm) and spectra were recorded with an Echelle spectrometer equipped with an ICCD camera. We investigated the evolution of atomic and ionic line emission intensities for different interpulse delay times between the laser pulses (from 100 ns to 50 mu s) and gate delays after the second laser pulse. We also varied the energy partition between the first and second laser pulse and the size of the irradiated spot at the sample surface. For the trace and side elements, we observed double-pulse LIBS signals that were enhanced as compared to single-pulse measurements depending on the interpulse delay time, the energy partition between the pulses, and the spot size. For the elements boron, copper, aluminum, titanium, chromium, potassium, and calcium limits of detection below 10 ppm were achieved.