有机光谱化学分析 (44).pdfVIP

P1: Hello everyone, welcome to this class--Organic Spectroscopic Analysis. In this lecture, we are going to learn another spectroscopy technique--X-ray Photoelectron Spectroscopy. P1：大家好，欢迎学习今天的课程——有机波谱分析。在这一节课中， 我们将学习另一种光谱技术-X 射线光电子能谱。 P2: First of all, what is XPS? X-ray Photoelectron Spectroscopy (XPS), also known as Electron Spectroscopy for Chemical Analysis (ESCA) is a widely used technique to investigate the chemical composition of surfaces.P2： 首先，什么是XPS ？ X 射线光电子能谱（XPS ），也称为化学分析电子 能谱（ESCA）是一种广泛使用研究表面化学成分的技术。 P4: XPS is often used for Surface Analysis, what information do we need? Firstly, Surface Composition Which elements are present? Secondly, Surface Geometry Arrangement of atoms Adsorption sites Bond lengths, and bond angles Thirdly, Chemical Bonds at Surfaces, including Bond making, breaking Bond order Vibrational Properties P4：XPS 通常用于表面分析，我们需要什么信息？ 一，表面成分 存在哪些元素？ 二，表面几何结构 原子排列 吸附部位 键长、键角 第三，表面的化学键，包括 键的形成与破坏 键级 振动特性 P5: Why is the XPS technique surface sensitive? There are two things which would be prevent an emitted electron from being detected : If it were captured before reaching the surface, or emitted in the wrong direction and never reached the surface ! If it lost energy before reaching the surface, that is ,it escaped from the solid and reached the detector, but with reduced kinetic energy. P5：XPS 技术为何对表面敏感？ 有两件事会阻止检测到激发的电子： 如果它在到达表面之前被“捕获”，或以错误的方向发射而从未到达 表面！ 如果它在到达表面之前损失了能量，即如果它从固体中逸出并到达了 检测器，但动能降低了。 P6: How can we demonstrate that XPS is surface sensitive? Consider again the two samples in previous section - such samples are often readily prepared by depositing material A by evaporation onto a substrate of material B. It is experimentally observed that in such a situation that XPS signals due to the substrate (material B) are rapidly attenuated, whilst those due to the condensed evaporant (material A) simultaneously