Robust raspberry-like metallo-dielectric nanoclusters of critical sizes as SERS substrates

Identifier:  imarina:9297956

Handle: https://hdl.handle.net/20.500.11797/imarina9297956

Authors:  Le Beulze, A; Gomez-Graña, S; Gehan, H; Mornet, S; Ravaine, S; Correa-Duarte, M; Guerrini, L; Alvarez-Puebla, RA; Duguet, E; Pertreux, E; Crut, A; Maioli, P; Vallée, F; Del Fatti, N; Ersen, O; Treguer-Delapierre, M

Abstract:
Raspberry-like nano-objects made of large plasmonic satellites (>10 nm) covering a central dielectric particle have many potential applications as photonic materials, superlenses and (bio-) sensors, but their synthesis remains challenging. Herein, we show how to build stable and robust raspberry-like nano-systems with close-packed satellites, by combining monodisperse silica particles (80 or 100 nm diameter) and oppositely charged noble metal nanoparticles (Au or Ag) with well-defined sizes (10-50 nm). The spectral characteristics of their associated plasmonic resonances (wavelength, linewidth, extinction cross-section) and the electromagnetic coupling between satellites were observed using the spatial modulation spectroscopy technique and interpreted through a numerical model. The composite nano-objects exhibit numerous hot spots at satellite junctions, resulting in excellent surface-enhanced Raman scattering (SERS) performance. The SERS efficiency of the raspberry-like clusters is highly dependent on their structure.