Plasmonic Nanowires for Wide Wavelength Range Molecular Sensing

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman spectroscopy (SERS) requires efficient plasmonic nanostructures.
• Existing methods for fabricating SERS substrates can be costly and complex.
• Developing cost-effective and high-performance SERS substrates is crucial for broader applications.

Purpose of the Study:

• To propose and fabricate a novel SERS substrate using standing nanowires.
• To investigate the plasmonic properties and enhancement capabilities of the proposed substrate.
• To demonstrate the cost-effectiveness and versatility of the fabrication method.

Main Methods:

• Fabrication of plasmonic active gold nanowires on iron disks using a galvanic process within an anodized alumina template.
• Characterization of nanowire array properties, including size, diameter, and spatial arrangement.
• Testing the substrate's performance for SERS applications using 633 nm and 830 nm laser lines.

Main Results:

• The galvanic fabrication process proved cost-effective and allowed control over nanowire dimensions and arrangement.
• The standing nanowire array exhibited broadband plasmonic enhancement suitable for visible and near-infrared (NIR) wavelengths.
• A significant Raman enhancement factor of up to 6 × 10⁴ was achieved compared to a flat gold surface.
• The trigonal pore arrangement resulted in polarization-independent efficiency.

Conclusions:

• The proposed standing gold nanowire array on iron disks is a highly effective and cost-efficient SERS substrate.
• The substrate demonstrates excellent plasmonic enhancement properties and broad applicability across different laser wavelengths.
• This fabrication approach offers a scalable solution for producing advanced SERS devices.