低能量電子繞射系統中之陰極透鏡的性質討論

作者:沈青嵩(國立臺灣師範大學理學院化學系)

摘要：

低能量電子繞射是研究固體表面結構最有力的工具，實驗時為使電子垂直入射樣品之表面，低能量電子繞射系統中的電子槍須瞄準陰極透鏡的第二焦點。
本文檢討在該系統中的陰極透鏡電位分佈及電子軌跡的各種計算方法。最後利用九點網路法以電腦計算電位分佈，並以廣泛之運動方程式追?電子在整個系統中的軌跡，文中並討論透鏡焦點與電子入射位置的關係及透鏡的鑑別率。數據顯示焦距與電子入射之動能大約無關。

《詳全文》

Cathode Lense in LEED

Author: Ching-song Shern

Abstract：

Low-energy electron diffraction (LEED) is a powerful tool of surface topo-graphy and surface structure investigations. The methods to calculate potential distribution and to trace the trajectories of electrons in the electrostatic cathode lense of LEED are discussed. Computer program to calculate the potential distri-bution with a nine-point network relaxation method and to trace the trajectories of electrons by a general equation of motion in the whole space of the system are available. The second focal length of the lense is independent of the incident kinetic energy of the electron at the first order approximation. The spherical abberration of the system is also concerned.