A comprehensive laser-induced plasma diagnostics of hafnium using fundamental and second harmonics of pulsed Nd: YAG laser.

Despite the proven applications of laser induced breakdown spectroscopy (LIBS) in multielement analysis, its broad applications are often hindered by challenges related to signal stability, analytical reliability, higher standard deviation (RSD) and lower signal to noise ratio (SNR). Hafnium is an element of significant importance due to its critical role in nuclear reactors and high-temperature applications. In this study, the first comprehensive LIBS-based investigation of laser induced plasma diagnostics of hafnium is reported, to address both the knowledge gap and the existing limitations of the technique. Various experimental parameters including effects of excitation wavelength, pulse energy, laser fluence, delay time and lens to sample distance were investigated, using fundamental (1064 nm) and second harmonic (532 nm) of a Q-switched Nd: YAG pulsed laser. The usual plasma parameters such as plasma temperature and electron density were also evaluated for both excitation wavelengths to verify local thermodynamic equilibrium conditions. The results revealed that optimized experimental conditions significantly reduce the measurement uncertainty and enhance the signal stability. The 532 nm laser irradiation yields superior performance, due to its higher mass ablation rate and more efficient energy coupling with the target material, which results in higher emission intensity and improved plasma characteristics. Overall, this study not only fills a critical research gap in LIBS-based spectroscopic analysis of hafnium but also provides valuable insights into the diagnostic performance of LIBS for advanced material characterization.