title: Quadrupole-enhanced Raman scattering.
abstract: Dark, nonradiating plasmonic modes are important in the Raman enhancement efficiency of nanostructures. However, it is challenging to engineer such hotspots with predictable enhancement efficiency through synthesis routes. Here, we demonstrate that spiky nanoshells have designable quadrupole resonances that efficiently enhance Raman scattering with unprecedented reproducibility on the single particle level. The efficiency and reproducibility of Quadrupole Enhanced Raman Scattering (QERS) is due to their heterogeneous structure, which broadens the quadrupole resonance both spatially and spectrally. This spectral breadth allows for simultaneous enhancement of both the excitation and Stokes frequencies. The quadrupole resonance can be tuned by simple modifications of the nanoshell geometry. The combination of tunability, high efficiency, and reproducibility makes these nanoshells an excellent candidate for applications such as biosensing, nanoantennaes, and photovoltaics.
authors.affiliation: Department of Physics, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Simon P
authors.initials: SP
authors.lastname: Hastings
authors.forename: Pattanawit
authors.initials: P
authors.lastname: Swanglap
authors.forename: Zhaoxia
authors.initials: Z
authors.lastname: Qian
authors.forename: Ying
authors.initials: Y
authors.lastname: Fang
authors.forename: So-Jung
authors.initials: SJ
authors.lastname: Park
authors.forename: Stephan
authors.initials: S
authors.lastname: Link
authors.forename: Nader
authors.initials: N
authors.lastname: Engheta
authors.forename: Zahra
authors.initials: Z
authors.lastname: Fakhraai
mesh_terms: D008958:Models, Molecular; D008968:Molecular Conformation; D057145:Nanoshells / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
keywords: QERS; Raman spectroscopy; SERS; plasmon resonance; quadrupole resonance; spiky nanoshells