Near-field coupling and SERS effects of palladium nanoparticle dimers |
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Authors: | FangXiong Ruan ShunPing Zhang ZhiPeng Li ZhiLin Yang DeYin Wu Bin Ren HongXing Xu |
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Institution: | 1 Department of Physics, Xiamen University, Xiamen 361005, China;
2 Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
3 Department of Chemistry, Xiamen University, Xiamen 361005, China |
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Abstract: | The linear optical properties and the surface-enhanced Raman scattering (SERS) effect of spherical palladium nanoparticle dimers are analyzed theoretically using generalized Mie theory. The calculation results demonstrate that the near-field coupling effect greatly influences the absorption, scattering and extinction spectra of nanoparticle dimers. The surface plasmon resonance wavelength red-shifts dramatically as the separation between nanoparticles decreases. Because of the near-field coupling between nanoparticles and the size effect, the maximum SERS enhancement factor at the ‘hot spot’ between palladium nanoparticle dimers is as high as 107–108, while the averaged SERS enhancement factor over the entire nanoparticle surface is in the range of 105–106. The deviation between the position of the peak in the extinction spectrum and the wavelength for maximum surface-averaged enhancement for the Pd nanoparticle dimers indicates that localized surface plasmon resonance has different influences on the far and near fields. These theoretical results may help to reveal the relationship between the far and near fields, as well as understand the mechanism of electromagnetic enhancement in the surface-enhanced scattering of transition metals. |
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Keywords: | surface-enhanced Raman scattering near-field coupling Mie scattering transition metals palladium |
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