Constant current etching of gold tips suitable for tip-enhanced Raman spectroscopy

Area of Science:

• Nanotechnology
• Spectroscopy
• Materials Science

Background:

• Tip-enhanced Raman spectroscopy (TERS) requires high-quality metallic tips for optimal performance.
• Existing methods for producing TERS tips can be complex and lack reproducibility.

Purpose of the Study:

• To introduce a simplified, automated method for fabricating gold tips for TERS.
• To demonstrate the effectiveness of these tips in high-resolution chemical analysis.

Main Methods:

• A single-step, constant current electrochemical etching process was employed.
• The automated process utilizes three key parameters: etching current, reference voltage, and gold wire immersion length.
• Optimization of parameters yielded gold tips with a smooth surface and ~20 nm radius of curvature.

Main Results:

• Reproducible fabrication of high-quality gold tips was achieved.
• TERS experiments on single-wall carbon nanotubes, p-aminothiophenol, and graphene were successfully conducted.
• Raman mapping of single-wall carbon nanotubes demonstrated a spatial resolution of approximately 15 nm.

Conclusions:

• The automated electrochemical etching method provides a reliable and efficient way to produce gold tips for TERS.
• The fabricated tips enable high-resolution chemical imaging of nanomaterials.
• This method facilitates advanced nanoscale spectroscopic analysis.