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Synthesis, Assembly, and Characterization of Monolayer Protected Gold Nanoparticle Films for Protein Monolayer Electrochemistry
Published on: October 4, 2011
SERS in PAH-Os and gold nanoparticle self-assembled multilayers.
N Tognalli1, A Fainstein, E Calvo
1Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica, 8400 San Carlos de Bariloche, Río Negro, Argentina. tognalli@cab.cnea.gov.ar
The Journal of Chemical Physics
|August 13, 2005
Summary
We studied poly(allylamine)-osmium complexes and gold nanoparticles multilayers. Coupled plasmon absorption enhances surface-enhanced Raman scattering (SERS), creating "hot spots" for improved signal detection.
Area of Science:
- Materials Science
- Nanotechnology
- Spectroscopy
Background:
- Self-assembled multilayers offer tunable properties for advanced applications.
- Osmium complexes and gold nanoparticles are key components in nanophotonics and sensing.
Purpose of the Study:
- To investigate the structural and surface-enhanced Raman scattering (SERS) properties of poly(allylamine)-osmium complex and gold nanoparticle multilayers.
- To understand the influence of nanoparticle assembly and plasmon coupling on SERS enhancement.
Main Methods:
- Atomic force microscopy (AFM) for structural analysis.
- Variable-angle spectroscopic ellipsometry for thickness and roughness measurements.
- Surface-enhanced Raman scattering (SERS) spectroscopy and Raman intensity micromaps.
- Numerical discrete dipole approximation (DDA) calculations.
Main Results:
- Homogeneous growth of the first gold nanoparticle layer without clustering.
- Formation of a compact multilayer structure after multiple immersion steps.
- Coupled plasmon absorption around 650 nm enhances SERS efficiency.
- Identification of SERS "hot spots" due to nanoparticle interactions.
- Shift in Raman intensity maxima with nanoparticle coverage, correlating with electronic transitions, plasmon resonance, and coupled-plasmon absorption.
Conclusions:
- The assembly process leads to controllable multilayer structures.
- Plasmon coupling in gold nanoparticle multilayers significantly enhances SERS.
- Numerical calculations provide a model for coupled plasmon absorption and redshifted Raman hot spots.
