Chemical Interface Damping Revealed by Single-Particle Absorption Spectroscopy.

Area of Science:

• Nanophotonics and Plasmonics
• Materials Science
• Surface Chemistry

Background:

• Plasmon-induced interfacial charge separation is key for efficient carrier extraction via direct plasmon decay.
• Chemical interface damping, caused by charge transfer, broadens plasmon line widths.
• Conflicting reports exist on how chemical interface damping impacts single-particle absorption spectra.

Purpose of the Study:

• To resolve discrepancies regarding chemical interface damping's effect on absorption spectra.
• To correlate absorption and scattering spectra of individual gold nanorods with and without a charge-accepting interface.
• To establish the utility of single-particle absorption spectroscopy for studying interfacial charge injection.

Main Methods:

• Single-particle scattering spectroscopy to measure homogeneous plasmon line width.
• Direct correlation of absorption and scattering spectra of individual gold nanorods.
• Utilizing TiO2-coated nanorods as a model system with a charge-accepting interface.
• Development of an analytical model for plasmon modes and damping effects.

Main Results:

• Chemical interface damping broadens the absorption line width of TiO2-coated nanorods.
• The absorption line width is narrower than the scattering line width.
• Chemical interface damping increases with higher resonance energies.
• An analytical model successfully explains the observed line width differences.

Conclusions:

• Single-particle absorption spectroscopy is a viable method for detecting interfacial charge injection.
• Understanding chemical interface damping is crucial for optimizing plasmonic devices.
• The study clarifies the relationship between plasmon decay, charge transfer, and spectral properties.