Plasmon In Quasi-one-dimensional Systems Of Finite Length

Low-dimensional nano-structure of the plasmon has unique optical properties forexample limited surface and static field enhancement, whether in the information，chemistry, biology or other fields have a wide range of applications. Plasmon is akind of elementary excitation, which electronic collective oscillation are relative tothe positive charge background. Surface plasmon is a elementary excitation whichemergence by the interaction between incident light and metal surface electroniccollective oscillation, it is a electromagnetic wave propagation along the interface ofmetal that strength is the largest at the interface between the metal of the field andthe intensity attenuation continually as the index in the direction perpendicular to theinterface. In the development of semiconductor technology and the device volumebecoming more and more small, studying properties for semiconductor surfacephysical have important practical value. Since the1950s Ritchie predicted thelow-energy excitation of the plasmon, a number of scientific researches are committedto study how feature of the plasmon in different shape of nano-structure. Theexperiment method that by the point charge to prove the existence of the surfacesplasmon can be traced back to Powell and Swan. They analysis of the metal interfaceelectron energy loss spectroscopy accurately and achieve dispersion relations of theplasmon.In this paper, we main purpose to study the electron excitation in the limitedlength quasi-one-dimensional of the system, realizing the collective oscillation ofelectron features by adjusting the length of the system, fixing number of electronic,and other the series of debugging method compared aspect of similar or different withinfinite system. The mainly content generalization of this paper up as follows:(l)We using a free election gas model obtained the eigen-equation of plasmaoscillation and numerical calculation for the plasmon spectrum based on the quantumlinear response theory and electromagnetic theory. Our results show that theexcitation spectrum of the finite-scale systems is discrete and very strong dependenton the size of systems. With the size of systems increase, the amount of Plasmonmode increase and the energy interval between the modes is decreased, but theexcitation energy is decreasing，at the same time, it is found that excitation spectrumis increasing with the electron density of the systems, and this is qualitativelyconsistent with macroscopic systems. (2)We studied the plasmon resonance in presence of external field, calculated thecharge density distribution and dipole moment. The results show that charge densitydistribution and electric dipole moment in the resonance is enhanced, in particular, isthe imaginary part increases more significantly. This indicates that the systems in theplasmon resonance will not only have enhancement of the near-field, andaccompanied by a huge increase of energy dissipation.