Configuration-Modulated Hot Electron Dynamics of Gold Nanorod Assemblies.

Comprehension and modulation of hot electron dynamics at an ultrafast time scale are crucial for exploring the hot electron-assisted energy transfer processes. Here, we report the hot electron dynamics of dispersed gold nanorods and their controlled assemblies measured by time-resolved pump-probe spectroscopy. Both assembly configurations are shown to accelerate the hot electron decay in comparison with dispersed nanorods. The hot electron dynamics exhibit different variations with aspect ratio in transverse and longitudinal polarizations. The hot electron lifetime and the spectral signature of the induced absorption modification are found to be highly sensitive to photon energy as well as assembly configuration and aspect ratios, showing different contributions of plasmon coupling and electron-surface scattering. This work not only improves the understanding of the underlying mechanisms of hot electron dynamics but also paves the way to optimize performance characteristics of hot carrier-assisted photocatalysis, photovoltaics, and all-optical high-rate photonic processing applications.