Gold particle interaction in regular arrays probed by surface enhanced Raman scattering

Area of Science:

• Plasmonics
• Surface-Enhanced Raman Spectroscopy (SERS)

Background:

• Two-dimensional arrays of gold nanoparticles on substrates are crucial for plasmonic applications.
• Understanding the Surface-Enhanced Raman Spectroscopy (SERS) effect requires detailed substrate characterization.

Purpose of the Study:

• To investigate the SERS effect of trans-1,2-bis(4-pyridyl)ethylene using lithographically designed gold nanoparticle arrays on a gold film.
• To analyze the plasmonic properties and Raman enhancement mechanisms of these arrays.

Main Methods:

• Fabrication of two-dimensional gold nanoparticle arrays on a gold film using lithography.
• Characterization of plasmon bands using extinction spectroscopy.
• Measurement of SERS spectra with varying topography parameters and laser excitation wavelengths.
• Correlation of optical properties with Raman enhancement.

Main Results:

• Gold nanoparticle arrays on gold films exhibit two distinct plasmon bands, unlike those on indium tin oxide.
• Laser excitation within the long wavelength plasmon band results in SERS spectra with a gain up to 10^8.
• Short wavelength band is attributed to a gold-glass interface plasmon, while the long wavelength band is linked to an air/gold surface plasmon mode modified by particle interactions.

Conclusions:

• The substrate topography significantly influences plasmon resonances and SERS enhancement.
• Particle-particle interactions play a key role in the observed plasmonic behavior and high Raman gain.
• The study provides insights into optimizing nanostructured substrates for enhanced SERS detection.