Structural and Optical Properties of PbS Nanoparticles Synthesized by the Radiolytic Method

Lead sulfide nanoparticles with diameter in the range of 9-45 nm were synthesized by the radiolytic method in aqueous solutions containing Pb2+ and thiol. PbS nanoparticles were identified by HRTEM, SAED, and XPS techniques. The irradiation dose plays a crucial role to control the size of the nanoparticles and consequently to modify their optical properties. These properties were studied by measuring the absorption and emission bands for each irradiation dose. For irradiation doses higher than 2 kGy, the PbS nanoparticles exhibit an emission band within the ultraviolet range (300-550 nm). This band shifts from 360 to 380 nm. The excitation of PbS nanoparticles shows that they display three emission bands in the near-infrared region around 900, 980, and 1100 nm. In addition, it is shown that the unusual emission bands of PbS nanoparticles are due to the presence of complexes of lead by thiol on the surface of the nanoparticles.