Influence of the laser wavelength on the self-absorption of Cu and Ni spectral lines by using LIBS technique

The current research is focusing on generation a plasma from a standard copper-nickel alloy using a Q-switched Nd:YAG laser with its fundamental wavelength (1064 nm) and its second harmonic generation (532 nm) in the air at atmospheric pressure. The results showed that the used wavelengths have a crucial effect on LIBS self-absorption implying choosing the right laser wavelength in the analysis as the calculated plasma temperatures were different upon using Cu and Ni spectral lines, one at a time. To get plasma temperatures with good confidence, the calculated plasma temperatures by two methods; Boltzmann plot (using Cu lines) and Saha-Boltzmann plot (using Ni lines) were corrected against self-absorption. Finally, a shorter excitation wavelength (532 nm) was shown to have spectral lines with higher electron densities since the absorbed energy by the ablated target is higher at 532 nm than that at 1064 nm.