High-yield synthesis and optical response of gold nanostars

Multipod Au nanoparticles (nanostars) with single crystalline tips were synthesized in extremely high yield through the reduction of HAuCl4 in a concentrated solution of poly(vinylpyrrolidone) (PVP) in N,N-dimethylformamide (DMF), in the presence of preformed Au nanoparticle seeds, but with no need for external energy sources. Nanostar dispersions display a well-defined optical response, which was found (through theoretical modeling) to comprise a main mode confined within the tips and a secondary mode confined in the central body. Calculations of the surface enhanced Raman scattering (SERS) response additionally show that this morphology will be relevant for sensing applications. © IOP Publishing Ltd.Funding from the Spanish Ministerio de Educaci´on y Ciencia is acknowledged in the form of a fellowship (PSK) and Grants MAT2004-02991 and NAN2004-08843-C03/C05.Peer Reviewe