Principles and Practice of Variable Pressure/Environmental Scanning Electron Microscopy (VP-ESEM) -- Contents -- Preface -- 1 A Brief Historical Overview -- 1.1 Scanning Electron Microscopy -- 1.1.1 The Beginnings -- 1.1.2 The Need for Added Capabilities -- 1.2 The Development of Imaging in a Gas Environment -- 1.2.1 Overcoming the Limits of Conventional SEM -- 1.2.2 Leaps and Bounds -- 2 Principles of SEM -- 2.1 Introduction -- 2.1.1 Why Use An Electron Beam? -- 2.1.2 The SEM Column -- 2.1.3 Why Do We Need a Vacuum System? -- 2.2 Electron Sources -- 2.2.1 Thermionic Emission Sources -- 2.2.2 Field Emission Sources -- 2.3 Electron Optics -- 2.3.1 Lenses -- 2.3.2 Lens Aberrations -- 2.4 Signals and Detection -- 2.4.1 Primary Electrons and the Interaction Volume -- 2.4.2 Backscattered Electrons -- 2.4.3 Secondary Electrons -- 2.4.4 X-ray Radiation -- 2.4.5 Cathodoluminescence -- 2.5 Practical Aspects of Electron Beam Irradiation -- 2.5.1 Radiation Damage -- 2.5.2 Minimising Specimen Charging - Low-Voltage SEM -- 2.5.3 Increasing Surface and Bulk Conductivities -- 2.6 SEM in Operation -- 2.6.1 Building Up an Image -- 2.6.2 Magnification -- 2.6.3 Signal-to-Noise Ratio -- 2.6.4 Contrast -- 2.6.5 Adjusting the Contrast -- 2.6.6 Resolution -- 2.6.7 Depth of Field -- 2.6.8 Image Capture -- 3 General Principles of VP-ESEM: Utilising a Gas -- 3.1 Introduction -- 3.2 VP-ESEM Instrumentation -- 3.2.1 Typical Features -- 3.2.2 Primary Electron Scattering in VP-ESEM - the General Case -- 3.2.3 Units of Pressure -- 3.3 Signal Generation in a Gas -- 3.3.1 Introduction -- 3.3.2 Direct Collection of Electrons and Ions -- 3.3.3 Collection of Photons - the Gas Luminescence Signal -- 3.3.4 Detecting Indirect Electron and Ion Currents -- 3.4 Imaging with Water Vapour -- 3.4.1 Introduction -- 3.4.2 Thermodynamic Equilibria -- 3.4.3 Nonequilibrium Conditions.

3.4.4 Practicalities of Stabilising Hydrated Specimens -- 4 Imaging and Analysis in VP-ESEM: The Influence of a Gas -- 4.1 Introduction -- 4.2 Background to Theoretical Calculations -- 4.2.1 Calculating the Mean Free Paths of Primary Electrons -- 4.2.2 Calculating Pressure-Dependent Variables -- 4.2.3 Estimating the 'Useful' Primary Electron Current -- 4.3 Which Gas? -- 4.3.1 Introduction -- 4.3.2 Usefulness of the Gas - Experimental Conditions -- 4.3.3 Ionisation and Excitation for Different Gases -- 4.3.4 Scattering of the Primary Electron Beam in Different Gases -- 4.4 Exploring the Gas Path Length -- 4.4.1 Introduction -- 4.4.2 Influence of GPL on the Skirt Radius -- 4.4.3 Gas Path Length and Useful Primary Electron Beam Current -- 4.4.4 Constraints on Reducing the Gas Path Length -- 4.4.5 Separating Gas Path Length from Working Distance -- 4.5 How Much Gas? -- 4.5.1 Introduction -- 4.5.2 Scattering of Primary Electrons as a Function of Pressure -- 4.6 X-ray Microanalysis in VP-ESEM -- 4.6.1 Introduction -- 4.6.2 Effects of Chamber Gas on X-ray Signals -- 4.6.3 Considerations for Minimising the Effects of the Gas -- 4.6.4 Post-Acquisition Methods to Correct for Scattering -- 5 Imaging Uncoated Specimens in the VP-ESEM -- 5.1 Introduction -- 5.2 Electronic Structure -- 5.2.1 The Energy Level Diagram -- 5.2.2 Conductors, Semiconductors and Insulators -- 5.3 Factors Affecting Secondary Electron Emission -- 5.3.1 Transport of Excited Electrons -- 5.3.2 Escape of Excited Electrons -- 5.4 The Influence of the Specimen on the System -- 5.4.1 The Effect of Charging - the General Case -- 5.4.2 Measuring Surface Potential -- 5.4.3 Conductive, Electrically Grounded Bulk Materials -- 5.4.4 Conductive, Electrically Isolated Materials -- 5.4.5 Nonconductive, Uncoated Materials -- 5.5 Time- and Temperature-Dependent Effects -- 5.5.1 Introduction.

5.5.2 Conductivity and Some Time-Dependent Effects -- 5.5.3 Charge Traps and Thermal Effects -- 5.6 Imaging Soft Materials -- 5.6.1 Introduction -- 5.6.2 Choosing an Appropriate Primary Beam Energy -- 5.6.3 Radiation Damage -- 5.7 Effects of Ions on Imaging -- 5.7.1 Introduction -- 5.7.2 Consideration of the Concentration of Positive Ions -- 5.7.3 Ion Mobility Effects -- 5.7.4 An Additional Surface Potential -- 5.7.5 Electron-Ion Recombination and Signal Scavenging -- 5.7.6 Combating Excess Ions -- 5.8 Imaging with a Gas: Summary -- 6 A Lab in a Chamber-in situ Methods in VP-ESEM and Other Applications -- 6.1 Introduction -- 6.2 Nanocharacterisation of Insulating Materials -- 6.2.1 High-Resolution Imaging -- 6.2.2 Anti-Contamination in the VP-ESEM -- 6.2.3 Nanometrology -- 6.2.4 Utilising Novel Contrast Mechanisms -- 6.2.5 Transmitted Electron Signals - STEM and Wet STEM -- 6.3 In situ Experiments -- 6.3.1 Deformation and Failure -- 6.3.2 Low-Temperature Experiments -- 6.3.3 High-Temperature Experiments -- 6.3.4 Condensation and Evaporation of Water -- 6.3.5 Processes Using Electron Beam Gas Chemistry in the VP-ESEM -- 6.3.6 High-Pressure Experiments -- 6.4 Other Applications -- 6.4.1 Introduction -- 6.4.2 Biological Specimens -- 6.4.3 Liquids and Soft Materials -- 6.4.4 Hard/Soft Composites and Hard Materials -- Index.