Multielemental self-absorption effect reduction in laser-induced breakdown spectroscopy by 10.6 µm high-repetition-frequency laser irradiation

The self-absorption effect seriously restricts the development of laser-induced breakdown spectroscopy (LIBS). Therefore, in this Letter, we propose 10.6 µm high-repetition-frequency laser irradiation assisted LIBS (LI-LIBS) to solve this problem. Furthermore, the efficacy of LI-LIBS in reducing the self-absorption effect is discussed. Results show that the full width at half-maximum (FWHM) of Al atomic emission line decreases by approximately 48%, and the FWHM of Cu emission line decreases by approximately 31%. Additionally, the self-absorption coefficient (SA) of Al element increases from 0.35 to 0.89 and the SA of Cu element increases from 0.57 to 0.75, approaching the ideal value of 1. These findings show that the self-absorption effect is greatly reduced. The mechanism is mainly attributed to inverse bremsstrahlung (IB) heating induced by the 10.6 μm laser irradiation at the plasma periphery. This study provides valuable insights into the reduction of LIBS self-absorption.