Freestanding and Permeable Nanoporous Gold Membranes for Surface-Enhanced Raman Scattering

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman spectroscopy (SERS) requires high-performance substrates for diverse applications.
• Existing SERS substrates often face limitations in scalability, mechanical stability, or enhancement efficiency.

Purpose of the Study:

• To develop and characterize novel freestanding porous gold membranes (PAuM) as effective SERS substrates.
• To evaluate the mechanical stability, scalability, and SERS performance of the fabricated PAuM.

Main Methods:

• Fabrication of large-scale, sub-30 nm thick freestanding porous gold membranes.
• Mechanical testing under pressure up to 3 bar.
• SERS measurements using graphene as a Raman probe, including wavelength-dependent and spatially resolved analysis.
• Numerical simulations to elucidate the enhancement mechanism.

Main Results:

• PAuM were successfully fabricated with varying morphologies and demonstrated mechanical stability.
• Local enhancement factors ranging from 10^4 to 10^5 were achieved.
• Numerical simulations identified nanoscale pores acting as optical slot antennas as the source of enhancement.
• Robust SERS enhancement was observed up to excitation power densities of 10^6 W cm^-2.

Conclusions:

• Freestanding porous gold membranes are easy-to-produce, scalable, and mechanically robust SERS substrates.
• The observed SERS enhancement is attributed to the unique nanoscale pore structure acting as optical antennas.
• PAuM show significant potential as building blocks for advanced SERS-based sensing technologies.