Proceedings - Viện Vật lý

Advances _________________________________________________________________________________in Optics, Photonics, Spectroscopy and Applications. Aug. 2006, Cantho, VietnamTEM observation:TEM images (Figure 3) demonstrated that the formed silver nanoparticles are ratheruniform, nearly spherical with the size distribution of 5 – 20 nm. The mean size ofthe particles is about 12 nm.Figure 3. TEM images of some samples of silver nanoparticlesA space of about 2-3 nm around every silver particle was obviously observed in theTEM picture. It did not exhibit any diffraction contrast and is considered as theorganic shell protecting silver core in side.The gain sizes from TEM observation are biger than crystallite sizes estimated byX-ray diffraction method because of in one grain might be exist more than onecrystallite Ag.UV-vis characterization:Nanoparticles of noble metals exhibit strong UV-vis surface plasmon[ 9, 10]absorption bands that are not present in the bulk metal. The previous studiesindicated that the characteristics of the absorption band depend on properties ofnanoparticles such as shape, size distribution and concentration. So this absorptionband obtained by UV-visible spectroscopy can provide information on particle size.UV-vis spectra of some synthesized samples were presented in Figure 4.Fig. 4. UV-vis spectra of samples of silver nanoparticles185