Influence of laser wavelength on self-absorption effect in laser-induced breakdown spectroscopy

Self-absorption effect seriously affects the accuracy of the quantitative analysis in laser-induced breakdown spectroscopy (LIBS), confining the further development of the technology. In this study, three laser wavelengths at ultraviolet (355 nm), visible light (532 nm), and infrared (1064 nm) were selected to study the influence of laser wavelength on self-absorption effect in LIBS. The effect of the laser wavelength on the spectral stability was also investigated. The results showed that when the wavelength was 1064 nm compared with the wavelength of 355 nm and 532 nm, the full widths at half maximum (FWHMs) of aluminum (Al) I 396.2 nm were reduced by 39 % and 23 %, the FWHM of potassium (K) I 766.5 nm were reduced by 58 % and 22 %. In addition, the laser wavelength was also closely related to the stability of the spectral intensity. In comparison with the laser wavelengths of 532 nm and 1064 nm, the best spectral repeatability occurred when the laser wavelength was 355 nm. The relative standard deviation (RSD) of the K I 766.5 nm was only 2.5 %. The results indicate that laser wavelength affects the self-absorption effect and spectral stability of LIBS, which means selecting an appropriate laser wavelength can reduce self-absorption and improve stability.