Effect of gold nanoparticle concentration on spectral emission of AlO molecular bands in nanoparticle-enhanced laser-induced Al plasmas

Abstract

Metal nanoparticles (NPs) for enhancing the signal intensity of laser-induced breakdown spectroscopy (LIBS) have received increasing attention in molecule spectroscopy. This study investigated the effect of gold nanoparticle concentration on the spectral emission of AlO molecular bands in nanoparticle-enhanced laser-induced Al plasmas using different concentrations (0–250 ng mL⁻¹) of Au NPs deposited on the pure Al substrate surface. The spectral emission of AlO (0–0) and (1–1) increased and then dropped as the concentration of Au NPs increased from 0 ng mL⁻¹ to 250 ng mL⁻¹ and reached the strongest emission at 0.98 ng mL⁻¹ concentration. In addition, the time-resolved characteristics of AlO spectra were also investigated, finding that the emission intensities and spectral lifetimes of AlO were different at different concentrations of Au NPs. The strongest peak intensity and longest spectral lifetime were observed at 0.98 ng mL⁻¹ concentration. Finally, the vibration temperature of AlO was obtained, and its trend with the concentration of Au NPs was found to be consistent with the spectral emission.