Experimental and ab initio ultrafast carrier dynamics in plasmonic nanoparticles

TL;DR

This paper combines experimental pump-probe measurements with first-principles calculations to accurately analyze ultrafast carrier dynamics in plasmonic nanoparticles, revealing detailed non-thermal and thermal carrier behaviors.

Contribution

It introduces a parameter-free theoretical approach that accounts for electronic-structure effects, improving understanding of carrier dynamics in plasmonic nanostructures.

Findings

Excellent agreement between theory and experiment in spectral and temporal features.

Identification of two main carrier response contributions: non-thermal and thermal.

Quantitative insights into ultrafast carrier relaxation processes.

Abstract

Ultrafast pump-probe measurements of plasmonic nanostructures probe the non-equilibrium behavior of excited carriers, which involves several competing effects obscured in typical empirical analyses. Here we present pump-probe measurements of plasmonic nanoparticles along with a complete theoretical description based on first-principles calculations of carrier dynamics and optical response, free of any fitting parameters. We account for detailed electronic-structure effects in the density of states, excited carrier distributions, electron-phonon coupling, and dielectric functions which allow us to avoid effective electron temperature approximations. Using this calculation method, we obtain excellent quantitative agreement with spectral and temporal features in transient-absorption measurements. In both our experiments and calculations, we identify the two major contributions of the initial response with distinct signatures: short-lived highly non-thermal excited carriers and longer-lived thermalizing carriers.