Calibration-free analysis of immersed metal alloys using long-pulse-duration laser-induced breakdown spectroscopy

Highlights: • Comparison of basic parameters in Air and Under Water LIBS • Strong Self-absorption is observed in underwater emission spectra. • We get better CF-LIBS results after self-absorption correction. -- Abstract: LASER-induced breakdown spectroscopy (LIBS) was applied using a long-duration single pulse on an immersed brass alloys target for spectroscopic studies. The plasma of the alloys was generated in air and underwater using a single pulse with longer duration of Nd:YAG laser. The spectral profiles of the Copper (Cu) emission lines were investigated, and we observed that the emission lines were severely affected by self-absorption in the underwater measurements. The LIBS signals were corrected before quantitative analysis through calibration-free laser-induced breakdown spectroscopy (CF-LIBS). The plasma parameters, electron number density, and plasma temperature were calculated, and the results were compared for both LIBS measurements. The results showed that the use of a long-duration pulse allows in situ quantitative analysis of the heavy metal alloys in underwater, such as Cu.