金属介电函数的正确运用——以金属纳米球诱导的二能级系统的基态能级移动为例  

Correct usage of the dielectric constant of metal——demonstrated by the energy level shift of a ground two-level system around a metal nanosphere

作　　者：黄勇刚[1] 文莎莎 杨红[1] 王小云[1] 邓科[1] 彭金璋[1] 赵鹤平[1] HUANG Yong-gang;WEN Sha-sha;YANG Hong;WANG Xiao-yun;DENG Ke;PENG Jin-zhang;ZHAO He-ping(College of Physics,Mechanical and Electrical Engineering,Jishou University,Jishou,Hunan 416000,China)

机构地区：[1]吉首大学物理与机电工程学院

出　　处：《大学物理》2020年第3期4-8,共5页College Physics

基　　金：国家自然科学基金(11964010,11464014,11564013,11464013);吉首大学教学改革项目(2017JSUJGA17,JG2017B02);湖南省研究生科研创新项目(CX2018B706,CX20190876)资助

摘　　要：金属对电磁场的响应包括自由和束缚电荷两部分的贡献,大学物理教学中通常分别用Drude模型和Lorentz模型描述,然而,以上模型所得的介电函数只在一段较窄的频率范围内能与实验数据吻合.因此,在实际科研工作中,当物理量与较宽频率范围内的电磁场响应有关时,原则上介电函数应当采用实验测量值而不能采用模型化的结果.本文以金属纳米球诱导的二能级系统的基态能级移动为例,分别展示采用模型化的介电函数和实验介电函数时,能级移动计算结果的差异.The electromagnetic response of metal contains the contribution of the free charges and the bound charges,which are usually theoretically descripted by the Drude model and the Lorentz model in collage physics respectively.However,only in a certain frequency range that the prediction from both models agrees with the experimental values.In practical scientific research,one should make use of the experimental values of the dielectric constant instead of the results from the Drude model or the Lorentz model when the physical quantity is related to the response over a wide frequency range in principal.In this work,the energy level shift of a ground two-level system around a metal nanosphere is numerically demonstrated with the electric permittivity of metal from the Drude model and the experimental values.Significant difference is observed,which implies the importance of the correct usage of the electric permittivity of metal.

关 键 词：介电函数 金纳米球 能级移动 光子格林函数 

分 类 号：O413-2[理学—理论物理]