Nonzero Wavevector Excitation of Graphene by Localized Surface Plasmons

Area of Science:

• Physical Chemistry
• Materials Science
• Nanotechnology

Background:

• Electrochemical surface-enhanced Raman scattering (SEERS) offers insights into material properties.
• Localized surface plasmons (LSPs) on noble metal nanostructures can enhance electromagnetic fields.
• Graphene's unique electronic properties are of significant interest for advanced applications.

Purpose of the Study:

• To investigate resonant excitation in single-layer graphene using SEERS.
• To explore the role of localized surface plasmons (LSPs) from gold nanodimers on graphene.
• To demonstrate a novel method for controlled electron or hole doping beyond far-field limits.

Main Methods:

• Electrochemical in situ SEERS measurements on single-layer graphene.
• Fabrication of gold nanodimer structures on defect-free graphene.
• Controlled electron and hole doping via electrochemical potentials.

Main Results:

• Observed resonant excitation induced by LSPs of Au nanodimers on graphene.
• Demonstrated generation of charge carriers at electrochemical potentials exceeding far-field limits.
• Confirmed nonzero wavevector excitation through observation of forbidden Raman bands in graphene.

Conclusions:

• SEERS with LSPs provides unique information on graphene doping and excitation.
• This approach enables overcoming the limitations of conventional far-field light illumination.
• Presents a novel pathway for enhancing optoelectronic interactions and photochemical reactions in graphene and semiconductors.