Plasmonic materials show great potential in applications such as plasmonic circuitry, three-dimensional, optical holography and surface plasmon amplification. However it is still a big challenge to broadly tune the plasmonic property besides the simple chemical synthesis approach.  

Bottom-up self-assembly is an effective way to prepare complex nanostructures with special plasmonic properties, thus greatly enriching our knowledge of how to design optimal optical properties of nanostructures. With the belief, Prof. ZHANG Yun and his research group from Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences closely cooperate with Prof. LI Jianfeng’s group from Xiamen University and develop a solution–based self-assembly strategy that allows for creating a series of subwavelength asymmetric nanostructures.

Two types of building blocks, Au nanospheres with diameters from 90 to 250 nm, Ag nanocubes with edges from 100 to 160 nm, are utilized to assemble the Au nanosphere and Ag nanocube subwavelength nanostructures with symmetry breaking, then coated with thick silica shells to stabilizing the whole nanostructures. The gaps between touched nanoparticles within an assembly unit is controlled by the thickness of ultrathin silica shells from 1 to above 10 nm.

Single particle scattering spectroscopy is then used to disclose the relationship between the structure and plasmonic property through the correlated transmission electron microscope (TEM) characterization and the 360° polarization-resolved scattering study. Pronounced Fano resonances appear when the polarization direction normal to the dimer axis.

The bottom-up self-assembly strategy developed here sheds some light not only on the design of novel plasmonic materials, but even more important on integrating the plasmonic units with the photocatalytic units to form functional nanostructures.

The work has recently been published in Nanoscale .

Schematic illustration of the self-assembly of the asymmetric nanostructures with adjustable building blocks (A and B) in solution (Image by Prof. ZHANG’s group)

Contact:

Prof. ZHANG Yun

Fujian Institute of Research on the Structure of Matter

http://english.fjirsm.cas.cn

Chinese Academy of Sciences

Email: zhangy@fjirsm.ac.cn