Understanding Time-Dependent Surface-Enhanced Raman Scattering from Gold Nanosphere Aggregates Using Collision Theory

Area of Science:

• Nanotechnology
• Plasmonics
• Spectroscopy

Background:

• Metal nanoparticle aggregates are crucial for surface-enhanced Raman scattering (SERS) due to localized electric fields.
• Time-dependent variations in SERS signals are observed, but the underlying cluster formation mechanisms are less understood.

Purpose of the Study:

• To investigate the impact of cluster formation mechanisms on time-dependent SERS signals from gold nanosphere aggregates.
• To experimentally and theoretically analyze the kinetics and dynamics of cluster formation.

Main Methods:

• Utilized dynamic light scattering (DLS), localized surface plasmon resonance (LSPR) spectroscopy, and SERS measurements.
• Employed theoretical calculations including interaction pair potential and collision theory.
• Systematically varied gold nanosphere concentration and diameter under diffusion-limited conditions.

Main Results:

• Gold nanosphere aggregates formed reproducibly in a diffusion-limited regime, adhering to a self-limiting cluster size model.
• The rate of cluster formation was explained by collision theory and interaction pair potential calculations.
• Time-dependent SERS signals were found to be predictable based on nanosphere concentration and size.

Conclusions:

• Cluster formation dynamics in the diffusion-limited regime are governed by principles of collision theory.
• Predictable SERS signals can be achieved by controlling gold nanosphere concentration and size.
• Understanding these formation mechanisms is key to optimizing SERS measurements.