科研之友
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摘要
We report the result of a numerical study of surface plasmon induced anomalous behaviors in TE light scattering by single silver and gold nanowires of radius alpha. Going beyond the restricted case of nondissipative and nondispersive scatterers often reported previously, the current numerical calculation is performed directly on the basis of Mie's general formula, adopting the refractive index data of Johnson and Christy. Our result does not show the appearance of well resolved and multipole resonances in Q(sca) plotted against q (= 2 pi alpha/lambda), for certain wire radii. It does show however, the growing contributions of the higher order modes as alpha increases. A series of closely-placed but well separated resonance curves nevertheless show up for varying wire radii within the range of small q, exhibiting systematic changes indicative of the size effects on the scattered waves. The further deduced Q(sca)(lambda) spectra display the distinct resonance curves for different wire radii showing peculiar mix of monotonous and nonmonotonous variations of the resonance peak and spectral width with increasing a, as a result of complicated competitions among the growing contributions of the higher order modes. Finally, while the silver and gold scatterers appear to exhibit qualitatively similar behaviors, they differ largely in details due to the significantly different indices of refraction and dispersive properties.
- 出版日期2014-3
