When light impinges on a metallic nanoparticle localised surface plasmons can be excited. These are the result of the collective behaviour of conduction electrons that oscillate coupled to an electromagnetic field. The energetic electrons generated after the decay of the plasmon are of great interest due to its potential applicability in diverse nanoplasmonic devices. Most of the models available in the literature treat the plasmon as a classical dipole field induced by the charge oscillation on the surface of the nanostructrure. We propose a quantum-mechanical model where the optical properties of the nanoparticle are calculated using linear response density functional theory. In this model, the plasmon is one of the excited states found and arises from the electron-electron interactions in the metal, without requiring the addition of a classical dipole field. After the excitation, the plasmon decays producing energetic electrons. In our model, the treatment of the plasmon as a boson allows us to derive an expression for the coupling matrix between the collective excitation and the single electrons in the system. Therefore, the hot carriers distribution can be calculated for the plasmon state, as shown in Figure 1, for different sizes and materials. We also study the decay of non-plasmonic excitations, such as electron-hole pairs, and find that they can result in similar hot carrier generation rates as plasmonic excitations<br/><br/>Our approach paves the way to describe hot carrier generation in the quantum plasmonic regime with potential application to quantum-controlled devices, including single-photon sources, transistors and ultra-compact circuitry at the nanoscale.

Hot carrier generation from single plasmons in metallic nanoparticles

2019 Spring National Meeting

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