Adsorption of linear aliphatic α,ω-dithiols on plasmonic metal nanoparticles: a structural study based on...

Area of Science:

• Nanotechnology
• Surface Chemistry
• Spectroscopy

Background:

• Understanding the adsorption of molecules on nanoparticles is crucial for designing nanomaterials.
• Linear aliphatic α,ω-dithiols possess unique properties due to their two thiol groups, enabling diverse applications.

Purpose of the Study:

• To investigate the adsorption mechanism of dithiols on silver and gold nanoparticles.
• To elucidate the influence of metal type and surface coverage on dithiols' structure and orientation.
• To explore the potential of dithiols in forming nanogaps and enhancing electromagnetic fields.

Main Methods:

• Surface-Enhanced Raman Scattering (SERS) spectroscopy was employed to analyze dithiols.
• SERS spectra provided structural marker bands to understand adsorption and coordination.
• Comparative analysis of dithiols on silver versus gold nanoparticles was performed.

Main Results:

• Dithiols exhibit distinct adsorption behaviors on silver and gold nanoparticles.
• Adsorption on gold nanoparticles resulted in more disordered aliphatic chain structures compared to silver.
• Dithiols adsorb perpendicularly, unlike monothiols, and can form controllable nanogaps.
• Intense SERS spectra observed down to 10⁻⁸ M indicate a large Raman enhancement factor of 5 × 10⁶.

Conclusions:

• Dithiols serve as effective linkers between metal nanoparticles, enabling controlled nanogap formation.
• The formed nanogaps generate significant electromagnetic field enhancements (hot spots).
• SERS is a powerful tool for studying molecular adsorption and interfacial phenomena on nanoparticles.