Precision plasmonics: Investigating the onset of quantum effects in gold nanoparticle dimers

• Applicant: Dr. Jun Hee Yoon
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2016 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 322224412

Dimers of noble metal nanoparticles (NPs) are the simplest model for plasmonic assemblies, which exhibit fascinating new optical properties. Quantum effects such as tunnelling are observed at very short gap distances or with a conductive gap medium. Theory can predict the onset of quantum effects in metal NP dimers. However, experimentalists have failed so far to synthesize and characterize the corresponding idealized dimer structures for a direct comparison with theory. This proposal thereby aims at the fabrication of highly symmetric dimers of spherical and cubic gold NPs. The use of molecular linkers with different chain lengths enables precise control of the gap distance in the NP dimer, while the number of conjugated double bonds controls the gap conductivity. Scattering experiments at the single-NP level together with correlative structural characterizations by high-resolution electron microscopy are performed. By systematically decreasing gap distance and increasing gap conductivity in single NP dimers, we can experimentally detect the onset of quantum effects in plasmonic dimers with high accuracy and precision, and thereby test the validity of predictions from theory.

• DFG Programme: Research Grants
• International Connection: Spain
• Cooperation Partner: Professor Javier Aizpurua, Ph.D.