SCANNING AND TRANSMISSION ELECTRON MICROSCOPY

AN INTRODUCTION

Stanley L. Flegler John W. Heckman, Jr. Karen L. Klomparens

Center for Electron Optics Michigan State University

W. H. FREEMAN AND COMPANY NEW YORK

CONTENTS Preface vii

1 INTRODUCTION 1

2 ELECTRON SOURCES AND ELECTRON LENSES 13

Electron Sources 13

Electron Lenses 19

3 VACUUM SYSTEMS 23

Vacuum Pumps Commonly Used in EM Labs 26

Methods of Measuring Vacuums 35

Vacuum Systems Used in Electron Microscopy 38

4 THE TRANSMISSION ELECTRON MICROSCOPE 43

Theory of Operation 44

Real Images 46

Virtual Images 47

Depth of Field and Depth of Focus 48

Anatomy of a Transmission Electron Microscope 49

Medium- and High-Voltage Transmission Electron Microscopy 63

5 THE SCANNING ELECTRON MICROSCOPE 65

Theory of Operation 67

Specimen-Beam Interactions 71

Machine Variables 82

Ultrahigh-Resolution SEMS 89

Environmental SEMS 89

v

vi CONTENTS

Scanning Transmission Electron Microscopes 90

Scanning Tunneling and Atomic Force Microscopy 93

6 SPECIMEN PREPARATION FOR TEM 97

Negative Staining of Small Particulates 98

Ultrathin Sectioning of Larger Samples 100

Vacuum Evaporators and Evaporation Techniques 126

Shadowcasting and Replica Techniques 132

Cytological Techniques 142

Preparation of Nonbiological Materials 148

7 SPECIMEN PREPARATION FOR SEM 151

Mounting 152

Coating for Conductivity 153

Special Methods for Various Sample Types 158

Biological Sample Preparation 159

Alternative Methods for Biological Samples 162

SEM Histochemistry for Biological Samples 167

8 X-RAY ANALYSIS 173

X-ray Production and Naming 174

Measuring the Energy and Wavelength of X Rays 177

Construction of the EDS Detector 178

Construction of the EDS X-Ray Analyzer 180

Outputs 182

Spectrum Accumulation and Interpretation 182

Optimizing the Detection of X Rays 185

Artifacts 187

Quantitative Analysis 191

Sample Preparation 196

9 ELECTRON MICROGRAPHIC TECHNIQUES 201

Silver Graphic Process 202

Photographic Printing 205

Transmission Electron Micrography 208

Scanning Electron Micrography 213

The Electronic Darkroom 215

Micrograph Presentation and Publication 217

Index 221