Terahertz plasmon and surface-plasmon modes in hollow nanospheres

Yiming Xiao,Jiaguang Hu,Wen Xu,Yaya Zhang

doi:10.1186/1556-276x-7-578

Abstract

We present a theoretical study of the electronic subband structure and collective electronic excitation associated with plasmon and surface plasmon modes in metal-based hollow nanosphere. The dependence of the electronic subband energy on the sample parameters of the hollow nanosphere is examined. We find that the subband states with different quantum numbers l degenerate roughly when the outer radius of the sphere is r2 ≥ 100 nm. In this case, the energy spectrum of a sphere is mainly determined by quantum number n. Moreover, the plasmon and surface plasmon excitations can be achieved mainly via inter-subband transitions from occupied subbands to unoccupied subbands. We examine the dependence of the plasmon and surface-plasmon frequencies on the shell thickness d and the outer radius r2 of the sphere using the standard random-phase approximation. We find that when a four-state model is employed for calculations, four branches of the plasmon and surface plasmon oscillations with terahertz frequencies can be observed, respectively.

Highlights

In recent years, there has been a great interest in the investigation of metal-based hollow nanostructures because of their unique characteristics such as low density, large specific area, mechanical and thermal stability, and surface permeability
We have found that when the diameter of the sphere r2 > 100 nm and the shell thickness d ∼ 10 nm, the energy levels for different l states roughly degenerate
It should be noted that at present, little research work has been carried out to look into the electronic subband structure of the hollow nanosphere structures using more powerful theoretical tools such as the first principle calculations which require large scale numerical computations and are CPU-consuming

Summary

Introduction

There has been a great interest in the investigation of metal-based hollow nanostructures because of their unique characteristics such as low density, large specific area, mechanical and thermal stability, and surface permeability. These advanced materials have been widely applied in catalysis [1], drug delivery [2,3], food and cosmetic industries [4], fuel cell [5,6], biotechnology [7], lubricant [8], sensing [9], photonic devices [10], micro/nanoreactors [11], etc.

Objectives

Methods

Results

Conclusion