Controlling the Multiscale Topography of Anodized Aluminum Oxide Nanowire Structures for Surface-Enhanced Raman...

Area of Science:

• Materials Science
• Nanotechnology
• Plasmonics

Background:

• Developing plasmonically active substrates is crucial for advanced optical applications.
• Controlling optical properties like absorption and reflection is key for sensing and colorimetry.

Purpose of the Study:

• To engineer a cost-effective, plasmonically active substrate for tunable optical properties.
• To explore the application of this substrate in near-infrared surface-enhanced Raman spectroscopy (SERS) and colorimetry.

Main Methods:

• Fabrication of unique bone-fire-like, funnel-shaped, vertically aligned anodized aluminum oxide (AAO) nanowire structures using a modified self-aggregation technique.
• Deposition of a 40 nm gold (Au) film onto AAO nanowire structures with varying lengths and topographies.
• Quantitative analysis of localized surface plasmon resonance excitation, reflection/absorption spectra, and SERS performance.

Main Results:

• Successfully fabricated unique AAO nanowire structures with tunable topography.
• Demonstrated control over reflection/absorption properties, ranging from <40% to >90%, by altering nanowire length and surface topography.
• Achieved a significant enhancement factor of 3.92 × 10^5 for rhodamine 6G (R6G) Raman signal in SERS applications.

Conclusions:

• Nanowire length and surface topography are effective parameters for tuning optical properties and colorimetric effects.
• The developed Au-coated AAO substrate shows great potential for sensitive SERS sensing applications in the near-infrared regime.