Aberration-Corrected Analytical Transmission Electron Microscopy E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: RMS - Royal Microscopical Society
• Sprache: Englisch

Seitenzahl: 447

Veröffentlichungsjahr: 2011

Beschreibung

The book is concerned with the theory, background, and practical use of transmission electron microscopes with lens correctors that can correct the effects of spherical aberration. The book also covers a comparison with aberration correction in the TEM and applications of analytical aberration corrected STEM in materials science and biology. This book is essential for microscopists involved in nanoscale and materials microanalysis especially those using scanning transmission electron microscopy, and related analytical techniques such as electron diffraction x-ray spectrometry (EDXS) and electron energy loss spectroscopy (EELS).

Leseprobe

Table of Contents

Current and future titles in the RMS-Wiley Imprint

Title Page

Copyright

List of Contributors

Preface

Chapter 1: General Introduction to Transmission Electron Microscopy (TEM)

1.1 What Tem Offers

1.2 Electron Scattering

1.3 Signals Which Could be Collected

1.4 Image Computing

1.5 Requirements of a Specimen

1.6 Stem Versus Ctem

1.7 Two Dimensional and Three Dimensional Information

References

Chapter 2: Introduction to Electron Optics

2.1 Revision of Microscopy with Visible Light and Electrons

2.2 Fresnel and Fraunhofer Diffraction

2.3 Image Resolution

2.4 Electron Lenses

2.5 Electron Sources

2.6 Probe Forming Optics and Apertures

2.7 Sem, Tem and Stem

References

Chapter 3: Development of STEM

3.1 Introduction: Structural and Analytical Information in Electron Microscopy

3.2 The Crewe Revolution: How Stem Solves the Information Problem

3.3 Electron Optical Simplicity of Stem

3.4 The Signal Freedom of Stem

3.5 Beam Damage and Beam Writing

3.6 Correction of Spherical Aberration

3.7 What does the Future Hold?

References

Chapter 4: Lens Aberrations: Diagnosis and Correction

4.1 Introduction

4.2 Geometric Lens Aberrations and Their Classification

4.3 Spherical Aberration-Correctors

4.4 Getting Around Chromatic Aberrations

4.5 Diagnosing Lens Aberrations

4.6 Fifth Order Aberration-Correction

4.7 Conclusions

References

Chapter 5: Theory and Simulations of STEM Imaging

5.1 Introduction

5.2 Z-contrast Imaging of Single Atoms

5.3 STEM Imaging Of Crystalline Materials

5.4 Incoherent Imaging with Dynamical Scattering

5.5 Thermal Diffuse Scattering

5.6 Methods of Simulation for ADF Imaging

5.7 Conclusions

References

Chapter 6: Details of STEM

6.1 Signal to Noise Ratio and Some of its Implications

6.2 The Relationships Between Probe Size, Probe Current and Probe Angle

6.3 The Condenser System

6.4 The Scanning System

6.5 The Specimen Stage

6.6 Post-Specimen Optics

6.7 Beam Blanking

6.8 Detectors

6.9 Imaging Using Transmitted Electrons

6.10 Signal Acquisition

References

Chapter 7: Electron Energy Loss Spectrometry and Energy Dispersive X-ray Analysis

7.1 What is EELS and EDX?

7.2 Analytical Spectrometries in the Environment of the Electron Microscope

7.3 Elemental Analysis and Quantification Using EDX

7.4 Low Loss EELS—Plasmons, IB Transitions and Band Gaps

7.5 Core Loss EELS

7.6 EDX AND EELS Spectral Modelling

7.7 Spectrum Imaging: EDX and EELS

7.8 Ultimate Spatial Resolution of EELS

7.9 Conclusion

References

Chapter 8: Applications of Aberration-Corrected Scanning Transmission Electron Microscopy

8.1 Introduction

8.2 Sample Condition

8.3 HAADF Imaging

8.4 Conclusions

References

Chapter 9: Aberration-Corrected Imaging in CTEM

9.1 Introduction

9.2 Optics and Instrumentation for Aberration-Corrected CTEM

9.3 Ctem Imaging Theory

9.4 Corrected Imaging Conditions

9.5 Aberration Measurement

9.6 Indirect Aberration Compensation

9.7 Advantages of Aberration-Correction for CTEM

9.8 Conclusions

References

Appendix A: Aberration Notation

Appendix B: General Notation

Symbols

Acronyms

Index

Color Plates

Current and future titles in the RMS-Wiley Imprint

Published

Principles and Practice of Variable Pressure/Environmental Scanning Electron Microscopy (VP-ESEM)—Debbie Stokes

Aberration-Corrected Analytical Electron Microscopy—Edited by Rik Brydson

Forthcoming

Understanding Practical Light Microscopy—Jeremy Sanderson

Atlas of Images and Spectra for Electron Microscopists—Edited by Ursel Bangert

Diagnostic Electron Microscopy—A Practical Guide to Tissue Preparation and Interpretation—Edited by John Stirling, Alan Curry & Brian Eyden

Practical Atomic Force Microscopy—Edited by Charles Clifford

Low Voltage Electron Microscopy—Principles and Applications – Edited by Natasha Erdman & David Bell

This edition first published 2011

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Library of Congress Cataloging-in-Publication Data

Aberration-corrected analytical transmission electron microscopy / edited by Rik Brydson ... [et al.].

p. cm.

Includes bibliographical references and index.

ISBN 978-0-470-51851-9 (hardback)

1. Transmission electron microscopy. 2. Aberration. 3. Achromatism. I. Brydson, Rik.

QH212.T7A24 2011

502.8′25 – dc23

2011019731

A catalogue record for this book is available from the British Library.

Print ISBN: 978-0470-518519 (H/B)

ePDF ISBN 978-1119-978855

oBook ISBN: 978-111-9978848

ePub ISBN: 978-1119-979906

Mobi ISBN: 978-1119-979913

List of Contributors

Andrew Bleloch, School of Engineering, University of Liverpool, Liverpool, UK

Lawrence Michael Brown FRS, Robinson College, Cambridge and Cavendish Laboratory, Cambridge, UK

Rik Brydson, Leeds Electron Microscopy and Spectroscopy (LEMAS) Centre, Institute for Materials Research, SPEME, University of Leeds, Leeds, UK

Alan J. Craven, Department of Physics and Astronomy, University of Glasgow, Glasgow, Scotland, UK

Peter J. Goodhew FREng, School of Engineering, University of Liverpool, Liverpool, UK

Sarah J. Haigh, Department of Materials, University of Oxford, Oxford, UK; University of Manchester, Materials Science Centre, Manchester, UK

Nicole Hondow, Leeds Electron Microscopy and Spectroscopy (LEMAS) Centre, Institute for Materials Research, SPEME, University of Leeds, Leeds, UK

Angus I. Kirkland, Department of Materials, University of Oxford, Oxford, UK

Peter D. Nellist, Department of Materials, Corpus Christi College, University of Oxford, Oxford, UK

Quentin Ramasse, SuperSTEM Facility, STFC Daresbury Laboratories, Daresbury, Cheshire, UK

Mervyn D. Shannon, SuperSTEM Facility, STFC Daresbury Laboratories, Daresbury, Cheshire, UK

Gordon J. Tatlock, School of Engineering, University of Liverpool, Liverpool, UK

All contributors helped in the preparation and editing of this book.

Preface

Electron Microscopy, very much the imaging tool of the 20th Century, has undergone a steep change in recent years due to the practical implementation of schemes which can diagnose and correct for the imperfections (aberrations) in both probe-forming and image-forming electron lenses. This book aims to review this exciting new area of 21st Century analytical science which can now allow true imaging and chemical analysis at the scale of single atoms.

The book is concerned with the theory, background and practical use of transmission electron microscopes with lens correctors which can mitigate for, and to some extent control the effects of spherical aberration inherent in round electromagnetic lenses. When fitted with probe correctors, such machines can achieve the formation of sub-Angstrom electron probes for the purposes of (scanned) imaging and also importantly chemical analysis of thin solid specimens at true atomic resolution. As a result, this book aims to concentrate on the subject primarily from the viewpoint of scanning transmission electron microscopy (STEM) which involves correcting focused electron probes, but it also includes a comparison with aberration correction in the conventional transmission electron microscope (CTEM) where the principal use of correctors is to correct aberrations in imaging lenses used with parallel beam illumination.

The book has arisen from the formation in 2001 of the world's first aberration corrected Scanning Transmission Electron Microscope Facility (SuperSTEM http://www.superstem.com) at Daresbury Laboratories in Cheshire in the UK. This originally involved a consortium of the Universities of Cambridge, Liverpool, Glasgow and Leeds, the Electron Microscopy and Analysis Group of the Institute of Physics and the Royal Microscopical Society and, very importantly, funded by the Engineering and Physical Sciences Research Council (EPSRC). Following its inception we have organised four postgraduate summer schools in 2004, 2006, 2008 and 2010. The current text has evolved from these Summer Schools and aims to be a (detailed) handbook which although introductory, has sections which go into some depth and contain pointers to seminal work in the (predominantly journal) literature in this area. We envisage that the text will be of benefit for postgraduate researchers who wish to understand the results from or wish to use directly these machines which are now key tools in nanomaterials research. The book complements the more detailed text edited by Peter Hawkes (Aberration corrected Electron Microscopy, Advances in Imaging and Electron Physics, Volume 153, 2008).

The form of the handbook is as follows:

In Chapters 1 and 2, Peter Goodhew and Gordon Tatlock introduce general concepts in transmission electron microscopy and electron optics. In Chapter 9 Mick Brown details the development of the concept of the scanning transmission electron microscope which arose from the pioneering vision of Albert Victor Crewe, who was notably born in Bradford in the West Riding of Yorkshire and was a graduate of Liverpool University. Probe forming lens aberrations and their diagnosis and correction are investigated further by Andrew Bleloch and Quentin Ramasse in Chapter 4. The theory of STEM imaging is outlined by Pete Nellist in Chapter 5, whilst the detailed instrumentation associated with STEM is given by Alan Craven in Chapter 6. Analytical spectroscopy in STEM and the implications of STEM probe correction are introduced in Chapter 7 by Rik Brydson and Nicole Hondow. Mervyn Shannon reviews some examples and applications of aberration corrected STEM in Chapter 8. Finally, in Chapter 9, Sarah Haigh and Angus Kirkland make comparisons with image correction in CTEM. All authors have very considerable experience in transmission electron microscopy and also aberration correction from either a practical or applied perspective and we have attempted to integrate the various separate chapters together so as to form a coherent text with a common nomenclature detailed in Appendix B. Although I have taken the nominal lead in editing the text, it has been a joint effort by all authors.

Tremendous thanks must go to all those associated with SuperSTEM over the years notably Meiken and Uwe Falke, Mhari Gass, Kasim Sader, Bernhard and Miroslava Schaffer, Budhika Mendis, Ian Godfrey, Peter Shields, Will Costello, Andy Calder, Quentin Ramasse, Michael Saharan, Dorothea Muecke-Herzberg, Marg Robinshaw, Ann Beckerlegge and Uschi Bangert. Dedicated SuperSTEM students have been invaluable and have included Sarah Pan, Paul Robb, Peng Wang, Linshu Jiang, Dinesh Ram, Sunheel Motru and Gareth Vaughan.

The final statements concerning the book should belong to Charles Lutwidge Dodgson (aka Lewis Carroll) who was born at Daresbury Parsonage less than a mile from the SuperSTEM laboratory and who famously wrote, ‘Through the (aberration-corrected) Looking Glass’ and ‘Alice in Wonderland’

‘Begin at the beginning and go on till you come to the end: then stop.’

But…….

‘I don't believe there's an atom of meaning in it.’

And……..

‘What is the use of a book, without pictures or conversations?’

Rik Brydson, Leeds 2011.

Chapter 2

Introduction to Electron Optics

Gordon Tatlock

School of Engineering, University of Liverpool, Liverpool, UK

2.1 Revision of Microscopy with Visible Light and Electrons

There are many parallels to be drawn between (visible) light optics and electron optics. The major difference, of course, is the wavelength of the illumination used: 450–600 nm for visible light but only 3.7  ×  10−3 nm for electrons accelerated through 100 kV. This difference not only controls the ultimate resolution of the microscope but also its size and shape. For example, the scattering angles are usually much smaller in electron optics and rays travel much closer to the optic axis.

Apart from the special case of a lensless projection image microscope, such as a field ion microscope, in which ions from an atomically sharp tip are accelerated across a gap to a large screen, giving a projected image of the source (Miller et al., 1996), most microscopes employ lenses to produce increased magnification of an object. Provided that the object is outside the focal length of the lens, this will lead to a projected, inverted image, which can be used as the object for the next lens, and so on. A typical compound microscope arrangement is illustrated in Figure 2.1 and applies equally to a light microscope or a TEM. Classical lens equations can then be used to link the object and image distances, and hence the magnification, to the focal lengths of the lenses (Hecht, 1998).

Figure 2.1 Schematic ray diagram of a compound projection microscope used as the basis for a light microscope or a transmission electron microscope.