Plasmon Enhancement Effect in Au Gold Nanorods@Cu2O Core鈥揝hell Nanostructures and Their Use in Probing Defect States

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• 作者：Xiaowei Shi ; Yinglu Ji ; Shuai Hou ; Wenqi Liu ; Hui Zhang ; Tao Wen ; Jiao Yan ; Min Song ; Zhijian Hu ; Xiaochun Wu
• 刊名：Langmuir
• 出版年：2015
• 出版时间：February 3, 2015
• 年：2015
• 卷：31
• 期：4
• 页码：1537-1546
• 全文大小：678K
• ISSN：1520-5827

文摘

Au@Cu₂O core鈥搒hell 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鈥?5 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.