Metal

Quantum mechanics

Metallurgy

Materials science

Nuclear physics

Atomic physics

Electronic structure

Surface plasmon

Physics

Nanotechnology

Hot electron

Free electron model

Condensed matter physics

Plasmon

Nanocrystal

Electron

Optoelectronics

Engineering physics

ACS Energy Letters

This Review discusses the electronic structure of plasmonic resonances in metal nanostructures, clarifying existing misconceptions on the topic. Here we underscore the key property of the plasmonic response in metal nanocrystals: the plasmon and its wave function are mostly composed of a large number of low-energy excitations, which involve electrons near the Fermi level. Simultaneously, some number of high-energy hot electrons are excited in a nanocrystal due to the scattering of electrons by surfaces and in hot spots. It is an established fact that plasmon excitations are well described by classical frameworks, considering the collective oscillation of low-energy carriers moving as the result of classical acceleration. This classical motion is intrinsically dissipative and leads to heating. On the other hand, the generation of hot electrons in nanocrystals is a quantum surface effect. The energy efficiency of such hot-electron processes is always limited. However, there are interesting possibilities for the hot-electron enhancement, which we discuss here in the context of applications for plasmonic photodetectors, photocatalysis, and ultrafast spectroscopy.

Electronic Structure of the Plasmons in Metal Nanocrystals: Fundamental Limitations for the Energy Efficiency of Hot Electron Generation