Simão André G, de Mendonça José P R F, Santiago Rosana B, de Moraes Pedro C G, Soares Paulo C, Guimarães Luiz G
Departamento Física, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-330, Juiz de Fora, Minas Gerais, Brasil.
Appl Opt. 2005 Jun 1;44(16):3370-6. doi: 10.1364/ao.44.003370.
We develop a semiclassical theory to explain the rapid ripple fluctuations in the extinction efficiency of light scattering by a transparent prolate spheroid. The theory is based on uniform asymptotic expansion of spheroidal radial functions. We have calculated the extinction efficiency for normal and oblique incidence. Our results suggest that the excitation of resonant electromagnetic modes inside a spheroidal particle is an important factor in the ripple structure. To verify this assumption and based on a Breit-Wigner formula, we develop a method to fit the peaks that appear in the spheroid's extinction cross section when some scattering parameters vary. In other words, our calculations suggest that narrow resonances are related to ripple fluctuations, whereas broad resonances contribute to extinction cross-sectional background.
我们发展了一种半经典理论来解释透明长椭球体光散射消光效率中的快速波纹波动。该理论基于椭球径向函数的一致渐近展开。我们计算了正入射和斜入射时的消光效率。我们的结果表明，椭球粒子内部共振电磁模式的激发是波纹结构的一个重要因素。为了验证这一假设并基于 Breit-Wigner 公式，我们开发了一种方法来拟合当一些散射参数变化时椭球体消光截面中出现的峰值。换句话说，我们的计算表明窄共振与波纹波动有关，而宽共振则对消光截面背景有贡献。
