Nonlinear optical properties of metal and semiconductor nanoparticles

The synthesis of metal (Au,Ag) and semiconductor (PbS) nanoparticles of specific size and morphology is reported. The shape of PbS nanoparticles has been varied from spherical to oval to cubic, by use of poly(vinyl alcohol) (PVA), DNA and ethylene glycol as stabilisers respectively. For the first time, a seeding method has been used to successfully prepare PVA stabilised gold and silver nanoparticles. Characterisation of the third order optical nonlinearity of the nanoparticles has been carried out using the Z-scan technique with values of Im chi ((3)) as large as 10(-10). Modulation of the magnitude of the nonlinear optical response with morphology in the case of the PbS nanoparticles is presented.