Angle-Resolved Plasmonic Properties of Single Gold Nanorod Dimers

Area of Science:

• Plasmonics
• Nanotechnology
• Optical Physics

Background:

• Individual gold nanorods exhibit distinct plasmonic dipole modes.
• Coupling of nanorods in dimers leads to hybridized bonding and antibonding resonance modes.
• Previous studies averaged signals over all excitation angles, limiting understanding of angle-dependent phenomena.

Purpose of the Study:

• To investigate the angle-resolved plasmonic properties of gold nanorod dimers.
• To demonstrate the tunability and sensitivity of hybridized resonance modes to excitation polarization and dimer orientation.
• To explore the influence of structure angle on resonance wavelengths and refractive index sensitivities.

Main Methods:

• Wet-chemical assembly of gold nanorod dimers with ~1 nm gap distance.
• Oblique excitation of individual dimers at various angles.
• Measurement and theoretical calculation of angle-resolved plasmonic properties.

Main Results:

• Two hybridized resonance modes (bonding and antibonding) were observed.
• These modes showed a strong dependence on the angle between excitation polarization and dimer orientation, following a cos²φ relationship.
• Resonance wavelengths and refractive index sensitivities were independent of the dimer's structure angle.
• Calculated angle-resolved properties closely matched experimental measurements.

Conclusions:

• Gold nanorod dimers exhibit angle-tunable plasmonic properties.
• The observed phenomena are independent of the nanostructure's orientation.
• These findings are significant for fundamental plasmonics research and the development of plasmon-based optical and optoelectronic devices.