Self-Organized Nanorod Arrays for Large-Area Surface-Enhanced Infrared Absorption

Area of Science:

• Plasmonics
• Spectroscopy
• Nanotechnology

Background:

• Surface-enhanced infrared absorption (SEIRA) spectroscopy offers high sensitivity for molecular detection.
• Existing methods often lack homogeneity over large areas or stability.
• Macroscopic, stable, and sensitive SEIRA requires advanced nanostructure engineering.

Purpose of the Study:

• To demonstrate the capabilities of SEIRA spectroscopy using large-area, self-organized nanorod antennas.
• To engineer gold nanorod antennas with tunable plasmon resonances for enhanced IR absorption.
• To achieve homogeneous and stable SEIRA activity over macroscopic areas.

Main Methods:

• Fabrication of large-area (cm²) self-organized (SO) gold nanorod antenna arrays.
• Engineering of polarization-sensitive localized plasmon resonances tunable over a broadband near- and mid-infrared spectrum.
• Utilizing self-assembled monolayers of octadecanthiol (ODT) molecules to demonstrate SEIRA activity.

Main Results:

• Demonstrated polarization-sensitive SEIRA activity, homogeneous and stable over macroscopic areas.
• Observed strong coupling between plasmonic excitation and molecular stretching modes, resulting in Fano resonances.
• Achieved signal amplitude improvement up to 5.7%, competitive with lithographic nanoantennas.
• Showcased stability of the enhanced signal across varying optical excitation spot sizes (micro- to macroscale).

Conclusions:

• Self-organized nanorod antennas enable highly sensitive and cost-effective SEIRA spectroscopy.
• The engineered nanostructures provide stable and homogeneous SEIRA response over large areas.
• This approach advances the development of practical nanosensor devices for molecular detection.