Deterministic assembly of metamolecules by atomic force microscope-enabled manipulation of ultra-smooth, super-spherical gold nanoparticles.

Atomic force microscope (AFM)-enabled manipulation of individual metallic nanoparticles (NPs) has proven useful for assembling diverse structural motifs of metamolecules. However, for the reliable verifications of their electric/magnetic behaviors and translations into practical applications (e.g., metasurfaces), currently available assembly of polygonal shaped metallic NPs with size and shape distributions should be further advanced. Here, we discover conditions for AFM-enabled, deterministic assembly of highly uniform, super-spherical gold NPs (AuNPs) into the metamolecules, which can show the designed electric/magnetic resonance behaviors in a highly reliable fashion. The use of super-spherical AuNPs together with the controlled adhesive properties of an AFM tip allows us to linearly and continuously push AuNPs toward the pre-programed directions and positions with minimized slipping away effect. Thus, a versatile and fast (as little as few minutes per each metamolecule) assembly of metamolecules with unprecedented structural fidelity becomes possible via AFM-enabled manipulation; enabling a high precision engineering of electromagnetic properties with metamolecules.