Au spherical nanoparticles obtained by the non-focused nanosecond pulsed laser irradiation of pristine octahedral nanoparticles (wavelength: 532 nm, fluence: 3.84 mJ cm-2, irradiation time: 60 s). (a) FE-SEM images for top view, and (b) tilted view. (c) A corresponding TEM image. (d) SAED pattern

(Imaged by LIU Dilong)

 SEM images of the self-assembled Au monolayer spherical nanoparticle arrays on a silicon substrate. (a) high and (b) low magnification with titled views. (c) FDTD simulation of electric-field intensity distribution (indicated by the color bar) of Au nanosphere array by self-assembly. (Imaged by LIU Dilong) 

Gold nanoparticles have attracted much interest because of their tunable Surface Plasmon Resonance (SPR) peaks, which bring important applications in the fields of chemistry, biology and materials sciences. Previous studies demonstrated that due to decrease in surface area gold nanoparticles with spherical shapes took shorter time to wrap the entire bulk compared with the nanorod. Therefore, it is quiet urgent to obtain homogeneous gold nanospheres without any facets. However, crystalline gold nanoparticles (NPs) prepared in a solution phase always grow anisotropic and accompany with a high tendency to form distinct facets naturally. Till now, it is still a challenge to obtain ultrasmooth gold nanospheres with high monodispersity.

To address this, a study team led by Prof. LI Yue from Institute of Solid State Physics (ISSP), Chinese Academy of Sciences (CAS) and Prof. LI Cuncheng from Jinan University (Shan Dong province) developed a facile and effective strategy to achieve monodispersed Au spherical nanoparticles. Ultra-smooth gold nanospheres with high monodispersity can be obtained by using a non-focused laser irradiation technology with optimizing the laser fluence and irradiation time. These gold nanospheres can self-assemble into periodic arrays by using an air/water interface self-assembly technique. The gold nanospheres and arrays possess distinct physical and chemical properties that will make them as an excellent and promising candidate for applying in sensing and spectroscopic enhancement, catalysis, energy, and biology.

This study is supported by the National Basic Research Program of China, Natural Science Foundation of China, Cross-disciplinary Collaborative Teams and International Innovative Research Team in CAS of CAS.

More details were published in Scientific Reports, entitled Rapid synthesis of monodisperse Au nanospheres through a laser irradiation-induced shape conversion, self-assembly and their electromagnetic coupling SERS enhancement.

Contact:

Prof. Yue LI, Ph.D Dilong LIU

Institute of Solid State Physics，Chinese Academy of Sciences

Hefei, Anhui 230000, China

Tel: 0654-65595323

E-mail: yueli@issp.ac.cn