Document Type : Original Article
Laser Photonics Research Center, Engineering Physics Department, Military Technical College, Cairo, Egypt.
Laboratory of Laser and New Materials, Faculty of Science, Cairo University, Giza, Egypt.
Detection of material ingredients is the main goal of the Laser-Induced Breakdown Spectroscopy (LIBS) technique. However, the light signal from the very little elemental concentration is small enough to produce large errors (relatively large limit of detection LOD). In order to enhance the light signal (spectral radiance) from the very small impurity concentrations, we suggested the addition of drops of gold nanoparticles (NPs) solution on the surface of metallic titanium in what is called nanoparticle-enhanced laser induced breakdown spectroscopy (NELIBS). The radiation from Nd:YAG pulsed laser at 1064 nm was used to irradiate the surface of titanium before and after the addition of nano-gold layer at an energy range from 60 mJ to 200 mJ in an open air. An echelle type spectrograph equipped with time controlled ICCD camera was used to resolve the emission spectrum from plasma. Ti I spectral lines at wavelengths of 453.32 and 498.17 nm were identified with recorded enhancement factors up to ×20, and this was achieved at the lower laser fluence of 4 J/cm2. Strong reduction in the plasma ignition threshold by factor of 40 from the pure bulk titanium to nano-gold coated titanium was achieved, with similar reduction of limit of detection LOD. A theoretical work is in advance to explain the origin of the enhanced emission.