Tadpole-shaped Au nano-particles fabricated by laser fragmentation of Au nano-spheres in liquid

Abstract

Tadpole-shaped Au nano-particles with controllable tails are successfully fabricated by simply using laser fragmentation of separated Au nano-spheres in liquid. The optimum laser power densities (1.5-3 GW∕cm 2 ) can enable part of the individual Au nano-sphere to be re-melted, released, and ultra-rapidly recondensed/crystallized on the outside of the original region. We find that the length of the tail in a tadpole-shaped Au nano-particle significantly increases from about 10 to 25 nm by increasing the laser power density. Benefiting from the unique structural features, the localized surface plasmon resonance (LSPR) absorption spectra of the tadpole-shaped Au nano-particles become broader by increasing the tail length. Moreover, the LSPR absorption band also exhibits a noticeable red shift from about 520 to 650 nm. Our results provide a convenient and valuable strategy to fabricated novel anisotropic-shaped nano-structures with fascinating properties.