title: Plasmon enhancement effect in Au gold nanorods@Cu2O core-shell nanostructures and their use in probing defect states.
abstract: Au@Cu2O core-shell nanostructures are fabricated to have a plasmon enhancement effect using Au nanorods (Au NRs) as a plasmon-tailorable core. By varying the concentration of Au NRs, we can tune the shell thickness in the range of 10-25 nm. The shell is composed of Cu2O nanocrystallites. Because of the thin shells, the extinction spectra at wavelength >500 nm are dominated by the Au core. However, the large dielectric constant of the shell causes an obvious red shift of the surface plasmon resonance (SPR) band of the Au nanorod. Besides, transverse octupolar SPR appears as a result of the anisotropy of the core and the high dielectric constant of the shell. The anisotropic geometry of the Au NR is found to support the octupolar resonances at smaller sizes than for their spherical counterpart. Theoretical simulations indicate that the transverse SPR bands are divided into two resonances, which are dipolar- and octupolar-dominant, respectively. The Cu2O shell degrades via a defect-mediated oxidative pathway, which is aggravated upon longitudinal SPR excitation. The SPR-mediated local field enhancement and resonance energy transfer are found to enhance the excitation of the defect states in the shell, thus providing a simple yet selective probing strategy for defect states.
authors.affiliation: State Key Laboratory for Powder Metallurgy, Central South University , Changsha 410006, PR China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Shi
authors.forename: Yinglu
authors.initials: Y
authors.lastname: Ji
authors.forename: Shuai
authors.initials: S
authors.lastname: Hou
authors.forename: Wenqi
authors.initials: W
authors.lastname: Liu
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Tao
authors.initials: T
authors.lastname: Wen
authors.forename: Jiao
authors.initials: J
authors.lastname: Yan
authors.forename: Min
authors.initials: M
authors.lastname: Song
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Hu
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wu