Effect of laser polarization on molecular emission from femtosecond LIBS
This study investigated the effect of laser polarization on the molecular bands of femtosecond laser-induced breakdown spectroscopy (LIBS). Results from AlO molecules indicated that the intensities of molecular emission bands under circular polarization in femtosecond LIBS were higher than those under linear polarization. The trend became more evident as laser energy increased. The vibration temperatures at different waveplate angles were also calculated to understand further the effect of laser polarization on the molecular emission signal. Finally, similar research on CN molecules for PMMA targets was carried out. The results showed that the emission intensity of the CN molecule was almost consistent with that of the AlO molecule. The study provided a method to improve the molecular emission signal in femtosecond LIBS with circular laser polarization.