Res. Chem. Intermed., Vol. 32, No. 2, pp. 103–113 (2006)  VSP 2006. Also available online - www.vsppub.com Synthesis of Au, Au/Ag, Au/Pt and Au/Pd nanoparticles using the microwave-polyol method KIRTI PATEL 1 , SUDHIR KAPOOR 2,∗ , DEVILAL PURSHOTTAM DAVE 1 and TULSI MUKHERJEE 2 1 Department of Chemistry, The Institute of Science, Mumbai 400 032, India 2 Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India Received 5 April 2005; accepted 13 May 2005 Abstract—Gold, Au/Ag, Au/Pt and Au/Pd bimetallic nanoparticles with varying mol fractions were synthesized in ethylene glycol and glycerol, using the microwave technique in the presence of a stabilizer poly(N -vinylpyrrolidone) (PVP). It was found that bimetallic colloids of Au/Ag, Au/Pd and Au/Pt form an alloy either on co-reduction of respective metal ions or on mixing individual sols. Keywords: Nanoparticles; microwave; electron transfer. INTRODUCTION In recent years, a burst of research activities has been seen in the synthesis and characterization of metal nanoparticles. The main reason for this is that nanoparticles have a variety of unique spectroscopic, electronic and chemical properties that arise from their small sizes and high surface/volume ratio. The study and preparation of inorganic crystalline particles on the nanometer scale has attracted considerable attention from both fundamental and applied research aspects. Hence, the quantum size effects, non-linear optical effects and electron dynamics of noble metal nanoparticles are being extensively investigated [1 –10]. Metal nanoparticles also exhibit new optical properties which are observed neither in the individual molecules nor in the bulk metals [11 –13]. One particular example is the presence of a strong absorption band in the visible region. This arises due to the surface-plasmon-oscillation modes of conduction electrons that are coupled through the surface to external electromagnetic fields [11 – 13]. In this regard, metal ∗ To whom correspondence should be addressed. Tel.: (91-22) 2559-0298. Fax: (91-22) 2550-5151. E-mail: sudhirk@apsara.barc.ernet.in