Increased Intraband Transitions in Smaller Gold Nanorods Enhance Light Emission
Autor: | Stephen Lee, Peter Nordlander, Behnaz Ostovar, Yi-Yu Cai, Arash Ahmadivand, Lawrence J. Tauzin, Stephan Link, Runmin Zhang |
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Rok vydání: | 2020 |
Předmět: |
Plasmonic nanoparticles
Photoluminescence Materials science General Engineering Physics::Optics General Physics and Astronomy 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Molecular physics 0104 chemical sciences Excited state General Materials Science Nanorod Spontaneous emission Light emission 0210 nano-technology Spectroscopy Plasmon |
Zdroj: | ACS nano. 14(11) |
ISSN: | 1936-086X |
Popis: | Photoinduced light emission from plasmonic nanoparticles has attracted considerable interest within the scientific community because of its potential applications in sensing, imaging, and nanothermometry. One of the suggested mechanisms for the light emission from plasmonic nanoparticles is the plasmon-enhanced radiative recombination of hot carriers through inter- and intraband transitions. Here, we investigate the nanoparticle size dependence on the photoluminescence through a systematic analysis of gold nanorods with similar aspect ratios. Using single-particle emission and scattering spectroscopy along with correlated scanning electron microscopy and electromagnetic simulations, we calculate the emission quantum yields and Purcell enhancement factors for individual gold nanorods. Our results show strong size-dependent quantum yields in gold nanorods, with higher quantum yields for smaller gold nanorods. Furthermore, by determining the relative contributions to the photoluminescence from inter- and intraband transitions, we deduce that the observed size dependence predominantly originates from the size dependence of intraband transitions. Specifically, within the framework of Fermi's golden rule for radiative recombination of excited charge carriers, we demonstrate that the Purcell factor enhancement alone cannot explain the emission size dependence and that changes in the transition matrix elements must also occur. Those changes are due to electric field confinement enhancing intraband transitions. These results provide vital insight into the intraband relaxation in metallic nanoconfined systems and therefore are of direct importance to the rapidly developing field of plasmonic photocatalysis. |
Databáze: | OpenAIRE |
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