Multipole Superradiance from Densely Assembled Metallic Nanoparticles

• Published in: Journal of physical chemistry. C 2013-07, Vol.117 (29), p.15247-15252
• Main Authors: Tokonami, Shiho, Hidaka, Shimpei, Nishida, Keisuke, Yamamoto, Yojiro, Nakao, Hidenobu, Iida, Takuya
• Format: Article
• Language: English
• Subjects: Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cooperative phenomena; superradiance and superfluorescence; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Lattice dynamics; Materials science; Nanoscale materials and structures: fabrication and characterization; Optics; Other topics in nanoscale materials and structures; Phonons and vibrations in crystal lattices; Physics; Quantum optics; Surface and interface electron states
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp4028244

The collective phenomenon of localized surface plasmons (LSPs) in a high-density collection of interacting metallic nanoparticles (NPs) is a crucial issue in various research fields such as optical physics, photochemistry, and biological science. Here, we report the dark-field measurement of the chemically controlled optical response of LSPs in densely assembled collection of a vast number of gold NPs on a microsphere (AuNP-covered bead). Remarkably, AuNP-covered beads exhibit plasmonic superradiance depending on sizes of binder molecules, where the giant spectral broadening more than 400 meV and significant enhancement of scattering have been observed. Furthermore, self-consistent theoretical analysis has also revealed that multipole collective modes contribute to the superradiance, leading to the enhancement by 2 orders of magnitude in both the far-field scattering and the localized fields of broadband light. The results obtained provide an innovative design principle for solar energy conversion and optical biosensors with incoherent light.