Surface-enhanced Raman spectroscopy (SERS) benefits from the high electric field, which is generated by the surface plasmon, even though it possesses high sensitivity and fingerprint information for molecules, the problems of poor reproducibility, high fabrication costs remain unsolved. Thus, it is increasingly in demand to design low-cost and reproducible hot spot nanostructures.

A study team led by Prof. YANG Liangbao from Institute of Intelligent Machines (IIM), Hefei Institutes of Physical Science induced capillary force to realize nanoparticle–nanowire single hot spot platform.

This nanostructure not only fabricates single hot spot with simple method, but also realize the highly reproducible features with sensitive and credible detection. The work was highlighted as the front cover of Journal of Materials Chemistry C.

In their design, they used the spontaneous capillary force to fabricate single hot spot, which consists of a sresearchersingle Ag nanowire (NW) and Au nanoparticles (AuNPs).

When single AuNP moves into the range dominated by spontaneous capillary imbibition, the Au NP can be rapidly captured, and then coupled to the NW, thereby providing giant localized coupled plasmons.

Moreover, the single hot spot can provide a "nano-channel" to trap molecules thanks to the presence of capillary imbibition. And the high quality SERS spectra for various molecules, reliable reproducibility and excellent sensitivity can be obtained.

Actually, the proposed approach not only overcomes the difficulty of combining two nanostructures together to form an efficient junction, but also provides a narrow enhancement factor distribution.

This work was supported by the National Science Foundation of China, Special Financial Grant from the China Postdoctoral Science Foundation.

The front cover for a capillary force-induced Au nanoparticle–Ag nanowire single hot spot platform for SERS analysis (Image by LI Pan)