Surface Plasmon Coupling of Compositionally Heterogeneous Core-Satellite Nanoassemblies

Area of Science:

• Nanotechnology
• Materials Science
• Physical Chemistry

Background:

• Understanding plasmon coupling in heterogeneous nanoparticles is essential due to energy mismatches and non-classical electrodynamic interactions.
• Core-satellite nanoassemblies offer a unique platform to study plasmon coupling in controlled environments.

Purpose of the Study:

• To explore surface plasmon coupling between silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) in core-satellite structures.
• To investigate the effect of varying core-to-satellite gap distances on plasmon coupling.
• To analyze the transition in plasmonic interactions at nanoscale gaps.

Main Methods:

• Preparation of core-satellite nanoassemblies using a novel assembly method.
• Utilizing 50 nm AgNPs as cores and 13 nm AuNPs as satellites, linked by alkanedithiol.
• Systematic variation of the gap distance between AgNP cores and AuNP satellites from 2.3 nm to 0.7 nm.

Main Results:

• Observed significant changes in plasmon coupling as the core-to-satellite gap distance was reduced.
• Demonstrated an abrupt transition from traditional hybridized plasmon modes to charge-transfer plasmons at approximately 1 nm gap.
• Analyzed the influence of the number of satellite nanoparticles on plasmon coupling.

Conclusions:

• The study highlights a critical transition in plasmon coupling mechanisms at nanoscale separations.
• Findings suggest that charge-transfer plasmons dominate interactions at sub-nanometer gaps, deviating from classical electrodynamics.
• The results provide fundamental insights into the behavior of heterogeneous metallic nanoparticles in close proximity.