Combination of RF-plasma jet and Laser-induced plasma for breakdown spectroscopy analysis of complex materials

Laser-induced breakdown spectroscopy method is modified using an external radiofrequency (RF) plasma jet that overlaps spatially with the laser-induced plasma. Short UV laser pulses (wavelength 193 nm) are employed to ablate iron oxide ceramics, zinc oxide ceramics and polyethylene pressed pellets in ambient air background. An RF generator (frequency 13.56 MHz, power ≤1 kW) and a gas nozzle system are employed to generate a continuous jet of argon and nitrogen plasma expanding into air. The optical emission of the overlapped plasma is analyzed using an Echelle spectrometer equipped with an intensified CCD camera. The time dependence of optical emission intensities and of plasma parameters is investigated by varying the spectrometer delay time with respect to the laser pulse. The emission intensities of major (Fe, Zn) and minor (Mn, Al) elements are moderately increased with the RF plasma jet (≤2×). The intensities of atomic lines and molecular bands from ablated polymer material are increased also.

Research highlights▶ Laser induced breakdown spectroscopy (LIBS) is combined with secondary excitation. ▶ An atmospheric pressure RF plasma jet is used for secondary excitation in air. ▶ LIBS intensity of minor and major element emission lines is significantly increased. ▶ Ionization degree and plasma temperature are increased depending on time.