Optical and Structural Properties of Pbs Nanoparticles Embedded in Starch

Pbs nanoparticles are synthesized in the polymer matrix, starch, by means of chemical method. The samples are prepared by varying pH, temperature and rotation time of the stirrer. The crystalline structure of the nanoparticles is studied by X-ray measurements. The average size of the nanoparticles and their crystalline structure are determined from the transmission electron microscopy and electron diffraction patterns, respectively. The optical properties of the samples are studied by UV-Vis spectroscopy. The absorbtion spectra of the samples display exciton absorbtion bands at much higher energy than the fundamental absorbtion bands of the bulk PbS. This result is a consequence of strong quantum confinement effects produced by the reduced size of the PbS nanoparticles as compared to exciton Bohr diameter of the bulk PbS.