Electron- and Lattice-Temperature Dependence of the Optical Response of Gold Nanoparticles

TL;DR

This study investigates how electron and lattice temperatures influence the optical response of gold nanoparticles, revealing non-linear effects and the significance of lattice heating through combined theoretical and experimental analysis.

Contribution

It provides a systematic analysis of the temperature dependence of gold nanoparticle absorption, including the first detailed study of lattice temperature effects on transient absorption bleach.

Findings

Confirmed the non-linear relationship between bleach and electron temperature.

Identified regions where bleach intensity linearly correlates with electron temperature.

Demonstrated a significant impact of lattice temperature on transient absorption bleach.

Abstract

Transient absorption spectroscopy is routinely used to study the electron dynamics in plasmonic gold nanoparticles. Typically, the transient absorption bleach is analyzed as measure for the electron temperature. However, the implicitly assumed linear dependence between bleach intensity and temperature has not been systematically studied. Similarly, the influence of lattice heating also lacks a detailed analysis. Here, we solve momentum-resolved metal Boltzmann-Bloch equations for a semi-analytic access to the temperature-dependent gold nanoparticle absorption. We confirm the theory with steady state and transient absorption experiments, define regions of linear correlation between transient absorption bleach intensity and electron temperature and reveal a strong impact of the lattice temperature on the TA bleach intensity.