1、X射线射线 光电子能谱光电子能谱 (XPS)2013-10表面分析表面分析The Study of the Outer-Most Layers of Materials (100 ).n Electron SpectroscopiesXPS: X-光电子能谱光电子能谱AES: 俄歇电子能谱俄歇电子能谱EELS:电子能量损失谱电子能量损失谱福州大学测试中心 XPS仪器简介X-射线光光电子能谱射线光光电子能谱 (XPS)n XPS 的物理的物理 基础基础n 结合能与结合能与 化学位移化学位移n XPS 谱的一般谱的一般 特性特性n XPS在不同领域的应用在不同领域的应用n XPS光谱仪及光谱仪及
2、新技术发展新技术发展 介绍介绍1. H. Hertz, Ann. Physik 31,983 (1887).2. A. Einstein, Ann. Physik 17,132 (1905). 1921 Nobel Prize in Physics.3. K. Siegbahn, Et. Al.,Nova Acta Regiae Soc.Sci., Ser. IV, Vol. 20 (1967). 1981 Nobel Prize in Physics.n XPS technique is based on Einsteins idea about the photoelectric effe
3、ct, developed around 1905.n The concept of photons was used to describe the ejection of electrons from a surface when photons were impinged upon itn During the mid 1960s Dr. Siegbahn and his research group developed the XPS technique.n In 1981, Dr. Siegbahn was awarded the Nobel Prize in Physics for
4、 the development of the XPS technique.XPS Background什么是光电子能谱什么是光电子能谱 ?u XPS (X-ray Photoelectron Spectroscopy)又被称为 ESCA (Electron Spectroscopy for Chemical Analysis)。u 它是以 X射线为探针检测由表面出射的光电子来获取表面信息的射线为探针检测由表面出射的光电子来获取表面信息的 ，这些光电子 主要来自表面原子的内壳层携带有表面丰富的物理和化学信息主要来自表面原子的内壳层携带有表面丰富的物理和化学信息 。u XPS作为表面分析技术的普
5、及归因于其高信息量、其对广泛样品的适应性以及其坚实的理论基础。一、一、 X-射线光电子能谱产生过程射线光电子能谱产生过程X-ray BeamX射线穿透深度射线穿透深度1mm，整个区域，整个区域的电子将被激发。的电子将被激发。X-ray excitation area 1x1 cm2. Electrons are emitted from this entire areaElectrons are extracted only from a narrow solid angle.1 mm210 nmConduction BandValence BandL2,L3L1KFermiLevelFree
6、 Electron LevelIncident X-ray e-1s2s2p光电离是一步过程A + h A +* + e (分立能量 )Ek = h EBA ：原子或分子H：光子能量(1) 电离过程 一次过程 (Primary process)Conduction BandValence BandL2,L3L1KFermiLevelFree Electron Level1s2s2pConduction BandValence BandL2,L3L1KFermiLevelFree Electron Level1s2s2pX-荧光过程 (辐射弛豫 ) 俄歇过程 (非辐射弛豫 )h(2) 弛豫过程
7、二次过程 (secondary process)俄歇电子能量并不依赖于激发源的能量和类型。ea结合能结合能 与化学位移与化学位移Vacumm LevelFermi LevelLowest state of energyEb, which is the work functionAt absolute 0 Kelvin the electrons fill from the lowest energy states up. When the electrons occupy up to this level the neutral solid is in its “ground state.”Energy Levels
