Plasmon-induced hot-carrier generation differences in gold and silver nanoclusters

• Published in: Nanoscale Vol. 11; no. 17; pp. 864 - 8615
• Main Authors: Douglas-Gallardo, Oscar A, Berdakin, Matías, Frauenheim, Thomas, Sánchez, Cristián G
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 25.04.2019
• Subjects: Absorption cross sections; Absorption spectra; Chemical reactions; Computer simulation; Electron density; Energy absorption; Gold; Icosahedral phase; Nanoclusters; Noble metals; Organic chemistry; Quantum confinement; Silver; Single electrons; Time dependence
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c9nr01352k

In the last thirty years, the study of plasmonic properties of noble metal nanostructures has become a very dynamic research area. The design and manipulation of matter in the nanometric scale demands a deep understanding of the underlying physico-chemical processes that operate in this size regimen. Here, a fully atomistic study of the spectroscopic and photodynamic properties of different icosahedral silver and gold nanoclusters has been carried out by using a Time-Dependent Density Functional Tight-Binding (TD-DFTB) model. The optical absorption spectra of different icosahedral silver and gold nanoclusters of diameters between 1 and 4 nanometers have been simulated. Furthermore, the energy absorption process has been quantified by means of calculating a fully quantum absorption cross-section using the information contained in the reduced single-electron density matrix. This approach allows us take into account the quantum confinement effects dominating in this size regime. Likewise, the plasmon-induced hot-carrier generation process under laser illumination has been explored from a fully dynamical perspective. We have found noticeable differences in the energy absorption mechanisms and the plasmon-induced hot-carrier generation process in both metals which can be explained by their respective electronic structures. These differences can be attributed to the existence of ultra-fast electronic dissipation channels in gold nanoclusters that are absent in silver nanoclusters. To the best of our knowledge, this is the first report that addresses this topic from a real time fully atomistic time-dependent approach. In the last thirty years, the study of plasmonic properties of noble metal nanostructures has become a very dynamic research area.