摘要
表面波(SW)是一种沿两媒质之间界面传播的电磁波。1899年A.Sommerfeld最早提出,TM型表面波可沿一根具有有限电导率的无穷长圆柱导线传输。1909年Sommerfeld又用Maxwell方程组处理了非辐射型表面波。表面等离子波(SPW)发生在金属与电介质的界面,自1957年以来为人所知,界面两侧呈消失态。SW与SPW的区别在于,SW发生于两电介质之间,而SPW仅在电介质与导体(例如金属膜)之间的界面上传播。也可认为SPW是SW的一种,它要求界面两边的介电常数一正一负,这可由一边用电介质而另一边用金属来满足。金属中的大量自由电子被当作高密度电子气体,其纵向密度起伏形成SPW可经由金属而传播。SPW的电磁场在界面上最大,在垂直表面的两个方向上指数地减小,这情况与SW相同。1991年黄志洵和曾诚提出了一个新的普遍化特征方程,用来描述圆波导壁电导率为有限值而内衬电介质层的情况。据此可以给出3类传播模式:内模,界面模和表面模。很明显,界面模即SW,表面模即SPW。使用由黄曾方程导出的近似式,可以算出TMs1u1模和TEs1u1模的衰减常数。近年来发展了一门新学科——以金属表面衰减全反射为基础的ATR光谱学,它是由体电磁波(VEMW)通过谐振激发造成SPW的技术,其实施是通过Otto方式(棱镜-空气-金属)或Kretschmann方式(棱镜-金属-空气)。本文讨论了棱镜SPW技术在确定金属膜介电常数ε和厚度d方面的应用。
A surface wave（SW） is one that propagates along an interface between two media.The propagation of a TM-type surface wave along an infinitely long cylindrical wire of finite conductivity,first discussed by A.Sommerfeld in 1899.Nonradiative surface waves are known as solutions of Maxwell＇s equations since Sommerfeld in 1909.A surface plasma wave（SPW） are given in the interface of a metal and a dielectric medium are well known since 1957,for the fields on both side of the interface to be evanescent states.The differentiation on the SW and the SPW is,SW propagates at the interface of two dielectric media,but the SPW only propagates at the interface of one dielectric media and other one of conductor——such as a metal film.So we say that SPW is a kind of SW,it needs permittivity positive in one side and negative in other side,which can be fulfilled in a dielectric medium and in a metal.In the metal,the free electrons are treated as an electron gas of high density.Then,the logitudinal density fluctuations,i.e.the SPW,will propagate through the metal.SPW＇s electromagnetic fields have their maximum in the interface and decay exponentially into the space perpendicular to the surface,as is characteristic for SW. In 1991,Z.X.Huang and C.Zeng derived a new general characteristic equation of circular waveguides,by assume that not only the metallic conductivity of the guide wall is finite,but also there is a uniform dielectric coat on the wall of the guide.Based upon that analysis,we gives three propagation modes：inner modes,interface modes and surface modes.Obviously,the interface modes are SW,the surface modes are SPW.When the HUANG-ZENG equation is approximated to another formula,the calculation results can obtained for attenuation constants of the TMsu11 mode and the TMsu11 mode.An attenuated total-reflection（ATR） spectroscopy of metal surface has developed in recent years,which makes use of the resonant excitation of SPW by linear coupling with volume electromagnetic waves（VEMW） in either an Otto configuration（prism-air-metal） or a Kretschmann configuration（prism-metal-air）.In this paper,the prism SPW technique for determining the dielectric constant εr and the thickness d of a metal film is discussed.
出处
《中国传媒大学学报（自然科学版）》
2011年第2期1-13,共13页
Journal of Communication University of China：Science and Technology
关键词
表面电磁波
表面等离子波
消失态
三棱镜
surface electro-magnetic waves
surface plasma waves
evanescent states
prism
