An Introduction to Surface Analysis by XPS and AES

John F. Watts, John Wolstenholme

• Publisher: Wiley
• Year: 2019
• Print ISBN: 9781119417583
• eBook ISBN: 9781119417644
• Edition: 2
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Provides a concise yet comprehensive introduction to XPS and AES techniques in surface analysis

This accessible second edition of the bestselling book, An Introduction to Surface Analysis by XPS and AES, 2nd Edition explores the basic principles and applications of X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) techniques. It starts with an examination of the basic concepts of electron spectroscopy and electron spectrometer design, followed by a qualitative and quantitative interpretation of the electron spectrum.

Chapters examine recent innovations in instrument design and key applications in metallurgy, biomaterials, and electronics. Practical and concise, it includes compositional depth profiling; multi-technique analysis; and everything about samples—including their handling, preparation, stability, and more. Topics discussed in more depth include peak fitting, energy loss background analysis, multi-technique analysis, and multi-technique profiling. The book finishes with chapters on applications of electron spectroscopy in materials science and the comparison of XPS and AES with other analytical techniques.

• Extensively revised and updated with new material on NAPXPS, twin anode monochromators, gas cluster ion sources, valence band spectra, hydrogen detection, and quantification
• Explores key spectroscopic techniques in surface analysis
• Provides descriptions of latest instruments and techniques
• Includes a detailed glossary of key surface analysis terms
• Features an extensive bibliography of key references and additional reading
• Uses a non-theoretical style to appeal to industrial surface analysis sectors

An Introduction to Surface Analysis by XPS and AES, 2nd Edition is an excellent introductory text for undergraduates, first-year postgraduates, and industrial users of XPS and AES.

1
Electron Spectroscopy: Some Basic Concepts

1.1 Analysis of Surfaces

All solid materials interact with their surroundings through their surfaces. The physical and chemical composition of these surfaces determine the nature of the interactions. Their surface chemistry will influence such factors as corrosion rates, catalytic activity, adhesive properties, wettability, contact potential, failure mechanisms, etc. Surfaces, therefore, influence many crucially important properties of the solid.

Despite the undoubted importance of surfaces, only a very small proportion of the atoms of most solids are found at the surface. Consider, for example, a 1 cm cube of a typical transition metal (e.g. nickel). The cube contains about 9 × 10²² atoms of which about 6 × 10¹⁵ are at the surface. The proportion of surface atoms is therefore approximately 1 in 10⁸ or 10 ppb. If we want to detect impurities at the nickel surface at a concentration of 0.1% then we need to detect materials at a concentration level of 0.01 ppb within the cube. The exact proportion of atoms at the surface will depend upon the shape and surface roughness of the material as well as its composition. The above figures simply illustrate that a successful technique for analysing surfaces must have at least two characteristics:

1. It must be extremely sensitive.
2. It must be efficient at filtering out signal from the vast majority of the atoms present in the sample.

This book is largely concerned with X‐ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). As will be shown, each of these techniques has the required characteristics but, in addition, they can answer other important questions:

1. Which elements are present in the near‐surface region of a solid?
2. Which chemical states of these elements are present?
3. How much of each chemical state of each element is present?
4. What is the spatial distribution of the materials in the near surface region in three‐dimensions and how does that vary with time?
5. If material is present as a thin film at the surface:
   1. How thick is the film?
   2. How uniform is the thickness?
   3. How uniform is the chemical composition of the film?

In electron spectroscopy, we are concerned with the emission and energy analysis of low energy electrons, usually in the range 20–2000 eV¹ (the use of X‐ray anodes that generate X‐rays having a photon energy much higher than 2000 eV is becoming more popular). These electrons are liberated from the sample being examined as a result of the photoemission process (in XPS) or the radiationless de‐excitation of an ionised atom by the Auger emission process in AES and scanning Auger microscopy (SAM). The distinction between AES and SAM is worthy of consideration. AES is a broad term that implies excitation of Auger electrons using a beam of electrons but makes no claim to be a technique that features high spatial resolution. SAM, on the other hand, always makes use of a finely focussed electron beam, typically in the range 10–100 nm, and provides results in the form of spatially resolved images derived from Auger electron data.

In the simplest terms, an electron spectrometer consists of the sample under investigation, a source of primary radiation, and an electron energy analyser all contained within a vacuum chamber, preferably operating in the ultra‐high vacuum (UHV) regime. In practice, there will often be a secondary UHV chamber fitted with various sample preparation facilities and perhaps ancillary analytical facilities. A data system will be used for data acquisition and subsequent processing. The source of the primary radiation fo...

Table of contents

• Cover
• Table of Contents
• Preface to First Edition
• Preface to Second Edition
• Acknowledgements
• 1 Electron Spectroscopy: Some Basic Concepts
• 2 Electron Spectrometer Design
• 3 The Electron Spectrum:
• 4 Compositional Depth Profiling
• 5 Multi‐technique Analysis
• 6 The Sample
• 7 Applications of Electron Spectroscopy in Materials Science
• 8 Comparison of XPS and AES with Other Analytical Techniques
• Glossary
• Bibliography
• Appendix 1: Auger Electron Energies
• Appendix 2: Table of Binding Energies Accessible with Al Kα Radiation
• Appendix 3: Documentary Standards in Surface Analysis
• Index
• End User License Agreement