Abstract

Formulas of efficient relaxation time are obtained for the cases when the free length of electrons is less or comparable with the characteristic dimensions of metallic regions. The frequency dispersion of optical characteristics of spherical bimetallic particles is calculated near plasma resonance in the absence of quantum-size effects. Retaining the style of common description of metallic particles based on the Mie–Drude theories, the frequency dependence of electric dipole polarizability of a two-layered metallic nanosphere was analyzed. The appearance of two polarizability maxima is the result of a difference in core and shell metals. The calculations are conducted for the following particles immersed into teflon: Au@Ag, Ag@Au, Au@Pt, Pt@Au, and Pt@Pd. It is demonstrated that the optical characteristics of bimetallic particles can be controlled by means of changing their composition and volumetric metal content. Cross-sections of absorption and scattering, as well as optical radiation efficiency of the particles in a wide spectrum range are calculated. Possible temperature of bimetallic particles at the absorption of an electromagnetic wave (for the photothermal therapy of malignant tumors) is estimated.

中文翻译：

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球形双金属纳米粒子的光学特性和表面等离激元尺寸位移的计算

摘要

当电子的自由长度小于或等于金属区域的特征尺寸时，可获得有效的弛豫时间公式。在不存在量子尺寸效应的情况下，在等离子体共振附近计算了球形双金属颗粒光学特性的频率色散。保留基于Mie-Drude理论的金属粒子的通用描述样式，分析了两层金属纳米球的电偶极极化率的频率依赖性。两种极化率最大值的出现是核和壳金属不同的结果。对于浸入特氟隆的以下颗粒进行计算：Au @ Ag，Ag @ Au，Au @ Pt，Pt @ Au和Pt @ Pd。证明了可以通过改变双金属颗粒的组成和体积金属含量来控制其光学特性。计算在宽光谱范围内颗粒的吸收和散射截面以及光辐射效率。估计了电磁波吸收下双金属颗粒的可能温度（用于恶性肿瘤的光热疗法）。