Emission characteristics of laser-induced plasma using collinear long and short dual-pulse LIBS

The collinear long and short dual-pulse LIBS (DP-LIBS) was employed to clarify the emission characteristics from laser-induced plasma. The plasma was sustained and became stable by the long pulsewidth laser with the pulse width of 60 μs under FR (free running) condition as an external energy source. Comparing the measurement results of stainless steel in air using SP-LIBS and DP-LIBS, the emission intensity was enhanced using DP-LIBS markedly. The temperature of plasma induced by DP-LIBS was maintained at higher temperature under different gate delay time and short pulse-width laser power conditions compared with these measured using SP-LIBS of short pulse width. Moreover, the variation rates of plasma temperature measured using DP-LIBS were also lower. The superior detection ability was verified by the measurement of aluminum sample in water. The spectra were clearly detected using DPLIBS, whereas it cannot be identified using SP-LIBS of short pulse width and long pulse width. The effects of gate delay time and short pulse-width laser power were also discussed. These results demonstrate the feasibility and enhanced detection ability of the proposed collinear long and short DP-LIBS method.