ABSTRACT

A burst of research activities has been seen in recent years for the synthesis and characterization of metal nanoparticles (NPs), which arise from their numerous possible applications in physics, chemistry, biology, materials science, and their di erent interdisciplinary elds (Bohren and Hu man 1983, Henglein 1993, Palato et al. 1994, Schmid 1994, Falkenhagen 1995, Kreibig and Vollmer 1995, Robert and Rao 1996, Jana and Pal 1999, Jana et al. 1999, 2001, Link and El-Sayed 1999, Gaponik et al. 2000, Pradhan et al. 2001). Because of their versatility in application, while evolution of the dispersion of small metallic particles with a tight size distribution is important, assembly of individual NPs into well-de ned aggregates has recently become a widely pursued objective (Murray et al. 2000, Fendler 2001, Niemeyer 2001a,b, Katz and Willner 2004). Most recently, emphasis has been placed on organizing or assembling metal NPs into de ned architectures, mainly for two reasons. First, such metal NP aggregates can display rich optical and electrical characteristics that are distinctly di erent from a simple collection of individual particles or the extended solid. Second, in relation to emerging electronic technologies, more sophisticated nanostructures are in demand [e.g., nanowires, nanotubes, and their two-dimensional (2D) and 3D NP assemblages].