Quantitative Microbeam Analysis

A.G Fitzgerald, B.E Storey, D.J Fabian

• Publisher: CRC Press
• Year: 2017
• eBook ISBN: 9781351420525
• Topic: Physical Sciences
• Subtopic: Atomic & Molecular Physics

Quantitative Microbeam Analysis provides a comprehensive introduction to the field of quantitative microbeam analysis (MQA). MQA is a technique used to analyze subatomic quantities of materials blasted from a surface by a laser or particle beam, providing information on the structure and composition of the material. Contributed to by international experts, the book is unique in the breadth of microbeam analytical techniques covered. For each technique, it develops the theoretical background, discusses practical details relating to choice of equipment, and describes the current advances. The book highlights developments relating to Auger electron spectroscopy in scanning electron microscopes and transmission electron microscopes and advances in surface analytical imaging and accelerated ion beam-surface interactions.

Quantification in AES and XPS

M. P. Seah

National Physical Laboratory
Teddington, Middlesex

1 Introduction

This volume covers a broad range of microbeam analytical methods and so we shall consider, here, some very general background. We shall then consider quantification using different methods and different levels of complexity. Many problems are adequately solved using very simple relationships whilst others require much more detailed analysis. Many of the aspects discussed in this chapter are now being installed by manufacturers into commercial software and the basic structures of expert systems are already being countenanced. Thus, in a few years time it is to be hoped that analysts can concentrate on surface science and applied surface science rather than working through many of the details presented here. However, if they do not understand these basics they will not be able to take effective advantage of what the software systems have to offer.

1.1 The basic principles of AES and XPS

In both Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) we use an incident radiation which strikes the surface under study. This surface emits low energy electrons, the energy spectrum of which exhibits lines characteristic of the atoms present at the solid surface. By measuring the spectrum with an electron spectrometer in ultra-high vacuum we obtain an analysis. In AES the incident radiation is usually an electron beam in the energy range 2 to 25 keV with a beam current in the range 1 na to 1μA. This flexibility allows both insulators and conductors to be studied with rather high sensitivity or, as discussed by Prutton in this volume, at high spatial resolution. At the current time the best spatial resolution observed is 5 nm (Janssen and Venables 1978). The incident electron ejects core electrons from atoms in the surface region and then these core holes are usually filled by electrons from higher levels in the same atom with the quantum of energy release being taken by a third electron which is ejected. In terms of the shell structure shown in Figure 1, the energy of the liberated electron, the Auger electron, is approximately E_A where

Figure 1. Schematic representation of (a) the Auger process and (b) photoelectron creation showing the atomic core levels.

EA≃E1−E2−E3⁢(1)

Figure 2 shows an Auger electron spectrum with the lines associated with several elements marked. Figure 2a shows a spectrum in the direct mode and Figure 2b the traditional differential mode used to enhance the visibility of the peaks.

In XPS the radiation is usually of monochromatic X-rays from A1 or Mg anodes. These give sharp lines with a width below 1 eV and in the useful energy range 1250 to 1500 eV. In some instruments the Bremsstrahlung background and weak satellite peaks are removed from the A1 radiation by using a monochromator. In the past this has not been popular because considerable intensity was lost. However, in today’s instruments, this is no longer the case...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Quantification in AES and XPS
• Surface Analytical Imaging
• Electronic Structure and Electron Spectroscopy
• Auger Electron Spectroscopy in the STEM
• Electron Energy-Loss Spectroscopy—EELS
• Light Element Microanalysis and Imaging
• A Comparison of Quantification Methods and Analytical Techniques
• Data Analysis and Processing
• Microscopy and Microanalysis of Insulating Materials
• Electron Specimen Interactions
• Electron Probe X-ray Microanalysis
• Energy Dispersive X-Ray Analysis (EDX) in the TEM/STEM
• Analysis and Imaging by Proton-Induced X-Ray Emission (PIXE)
• Ion-Beam Analytical Techniques—Rutherford Backscattering, Elastic Recoil and Nuclear Reaction Analysis
• Quantitative Analysis of Solids by SIMS and SNMS
• Static SIMS
• Applications of Surface, Interface and Thin Film Analysis in an Industrial Research Laboratory
• Ion-Induced Auger Electron Emission From Solids
• Resonance Ionisation Mass Spectrometry (RIMS)
• Appendix: a list of Acronyms
• Contributed papers by students
• List of Participants
• Index