Decoupling Absorption and Scattering Reveals Nanoscale Structural Evolution of Plasmonic Nanostructures in Real Time

Area of Science:

• Nanotechnology
• Materials Science
• Optical Physics

Background:

• Plasmonic nanostructures confine light, crucial for applications, but their precise structural control requires understanding growth dynamics.
• Current methods like UV-Vis spectroscopy merge absorption and scattering, obscuring vital information on plasmon evolution.
• Noninvasive tools are needed to monitor growth in delicate colloidal environments.

Purpose of the Study:

• To develop and validate a real-time optical platform for distinguishing absorption and scattering signals from plasmonic nanostructures.
• To reveal optical information inaccessible to conventional extinction spectroscopy during nanostructure formation.
• To link observed growth dynamics and anisotropy to the redistribution of radiative and nonradiative plasmon responses.

Main Methods:

• An automated optical platform was designed for real-time tracking of absorption and scattering.
• The platform's efficacy was validated using simulations and applied to various nanoparticle shapes.
• The technique was used to analyze gold nanoparticle aggregation and gold nanorod formation.

Main Results:

• The platform successfully separated absorption and scattering, providing insights into coupled plasmon modes during aggregation.
• Three distinct growth stages were identified during gold nanorod formation.
• A transition from longitudinal-dominated to transverse-dominated growth was linked to a scattering-to-absorption ratio inversion.

Conclusions:

• Absorption and scattering are practical, complementary probes for tracking nanoscale growth pathways.
• The developed method offers a new optical signature to understand growth anisotropy and plasmon response.
• This work advances the precise structural control of plasmonic nanostructures.