Anomaly in the relaxation dynamics close to the surface plasmon resonance

TL;DR

This paper explains the anomalous relaxation dynamics near the surface plasmon resonance in noble-metal nanoparticles, highlighting a frequency-dependent slowdown in transmission evolution that is independent of interband transitions.

Contribution

It introduces a new interpretation for the relaxation anomaly based on temperature-dependent plasmon properties, applicable to various nanoparticle types.

Findings

Strong frequency dependence in transmission dynamics near resonance

Slowdown in relaxation below the plasmon frequency

Interpretation independent of interband transition effects

Abstract

We propose an explanation for the anomalous behaviour observed in the relaxation dynamics of the differential optical transmission of noble-metal nanoparticles. Using the temperature dependences of the position and the width of the surface plasmon resonance, we obtain a strong frequency dependence in the time evolution of the transmission close to the resonance. In particular, our approach accounts for the slowdown found below the plasmon frequency. This interpretation is independent of the presence of a nearby interband transition which has been invoked previously. We therefore argue that the anomaly should also appear for alkaline nanoparticles.