Relaxation\nChannels of Two Types of Hot Carriers in\nGold Nanostructures

A fundamental understanding of hot\ncarrier relaxation in metal\nnanostructures is essential for realizing their application potential\nin energy conversion and photocatalysis. Despite previous investigations\nof the relaxation of hot carriers generated by surface plasmon resonance\n(SPR) excitation and interband transitions (IBTs), the hot carrier\nrelaxation lifetimes and their associated mechanisms remain unclear.\nHerein, we demonstrate two distinct hot carrier relaxation channels\nin gold plasmonic nanostructures. The experimental observations reveal\nthat the hot carrier relaxation is faster following SPR excitation\nthan that from IBTs in gold nanoparticles and nanorods. The experimental\nresults and theoretical calculations indicate that the numerous plasmon-induced\nhot carriers undergo surface-mediated carrier–carrier scattering\nin large gold nanostructures, whereas almost all IBT-induced hot carriers\nexperience bulk carrier–carrier scattering. These findings\nadvance our understanding of hot carrier relaxation and contribute\nto a clearer microscopic description of scattering channels in plasmonic\nnanostructures.