Laser deposition and transformation of gold nanospheres and nanorods

We have succeeded in the deposition of thiol-capped gold nanoparticles on the surface of a transparent substrate, by pulsed 532-nm laser irradiation with appropriate beam patterns. The deposition was ascribed to the formation of unstable particles generated by laser-induced coagulation and fusion of the gold nanoparticles in cyclohexane. This method was applied to spatio-selective electroless copper plating of a membrane filter and an inner wall of a capillary tube. The gold nanoparticles functioned as catalytic seeds for electroless plating. We have developed a novel and simple method for the preparation of rod-like gold nanoparticles (gold NRs), by the combination of chemical reduction and photo-irradiation. Taking advantages of the dichroic property of NRs, shape transformation of NRs was carried out in a poly(vinyl alcohol) film. The NRs were transformed into spherical particles even by one shot of a linearly polarized pulsed-laser light (1064 or 532 nm). Orientation-selective transformation of the NRs was possible.