Preface ...................................................... xiii
Acknowledgements ............................................. xvii
The Authors ................................................... xix
Chapter 1 Introduction to Characterization of Nanostructures ... 1
1.1 Nanotechnology—In the Beginning There Was the Idea ......... 1
1.2 Nanotechnology as a Practical Proposition .................. 1
1.3 What Is Nanotechnology? .................................... 2
1.3.1 Nanotechnology - Top-Down ........................... 3
1.3.2 Nanotechnology - Bottom-Up .......................... 4
1.3.3 Nanotechnology - A Socio-Economic Definition ........ 6
1.4 Materials Characterization - What Is It? ................... 7
1.4.1 Strategy Versus Tactics of Materials
Characterization .................................... 8
1.4.1.1 Meso-Versus Nano-scale ..................... 9
1.4.1.2 Dimensionality and Size Regimes of
Meso/Nanostructures ........................ 9
1.4.1.3 Dimensionality ............................ 10
1.4.2 Macro-/Micro-scale Versus Nano-scale Materials
Characterization ................................... 11
1.5 Current State of 'Best Practice' and QA ................... 12
References and Useful Reading ............................. 12
Bibiliography ............................................. 13
SECTION I Techniques and Methods
Chapter 2 Electron-Optical Imaging of Nanostructures
((HR)TEM, STEM, and SEM) ....................................... 17
2.1 Introduction .............................................. 17
2.2 ТЕМ Overview .............................................. 18
2.2.1 Magnetic Lenses and Aberrations .................... 19
2.2.2 Spherical Aberration ............................... 21
2.2.3 Chromatic Aberration ............................... 21
2.2.4 Resolution in the Presence of Aberrations .......... 21
2.3 Interactions of Electrons with Matter ..................... 23
2.3.1 High-Resolution Image Formation .................... 23
2.4 Aberration Correction ..................................... 27
2.5 Scanning Transmission Electron Microscopy (STEM) .......... 27
2.5.1 Technical Implementation ........................... 29
2.5.2 Diffraction Information from STEM .................. 30
2.6 The Issue of Radiation Damage during Imaging and
Analysis .................................................. 31
2.7 SEM ....................................................... 32
2.7.1 Technical Overview ................................. 32
2.7.2 Cold-Cathode Field Emission ........................ 32
2.7.3 Point-to-Point Resolution .......................... 33
2.7.4 Depth of Field ..................................... 34
2.7.5 Imaging Modes ...................................... 35
2.7.5.1 Secondary Electron Imaging ................ 35
2.8 Examples of SEM Performance ............................... 36
2.9 Optimization of Image Quality ............................. 37
2.9.1 Insulating Materials ............................... 37
Acknowledgements .......................................... 37
Appendix: Definitions of Acronyms Used Widely for
Description of Electron Microscopy (in
Alphabetical Order) ................................ 39
References ................................................ 39
Chapter 3 Electron-Optical Analytical Techniques .............. 41
3.1 Introduction .............................................. 41
3.2 Loss Processes ............................................ 41
3.2.1 EDS Spectral Notation .............................. 42
3.2.2 EDS Spectra ........................................ 43
3.2.2.1 Fluorescence Yield (со) ................... 45
3.3 EELS ...................................................... 45
3.3.1 EELS Spectral Features ............................. 45
3.4 Technical Implementation and Methods ...................... 47
3.4.1 EDS ................................................ 47
3.4.1.1 Quantification of EDS Spectra ............. 49
3.4.2 EELS ............................................... 50
3.5 Complementarity of EDS and EELS: A Case Study ............. 51
Acknowledgements .......................................... 60
References ................................................ 60
Chapter 4 Photon-Optical Spectroscopy - Raman and
Fluorescence ................................................... 61
4.1 Introduction .............................................. 61
4.2 Raman Spectroscopy ........................................ 61
4.2.1 Physical Principles ................................ 61
4.2.2 A Formal Classical Description of the Raman
Process ............................................ 63
4.2.3 SERS - Surface Enhanced Raman Spectroscopy ......... 64
4.2.4 TERS - Tip Enhanced Raman Spectroscopy ............. 65
4.2.5 Technical Implementation and Analytical Methods .... 65
4.3 Fluorescence Spectroscopy ................................. 66
4.3.1 Technical Implementation and Operational Modes ..... 67
4.3.2 Fluorescence Spectroscopy - Biomolecular
Applications ....................................... 69
4.3.3 Spectroscopic Analysis of Quantum Dots ............. 70
4.3.4 Carbon-Based Nanostructures and Raman
Spectroscopy ....................................... 70
Acknowledgements .......................................... 74
References ................................................ 74
Chapter 5 Scanning Probe Techniques and Methods ............... 77
5.1 Introduction .............................................. 77
5.1.1 Essential Elements of SPM .......................... 77
5.1.1.1 Cost-Effectiveness ........................ 78
5.1.1.2 Platform Flexibility ...................... 78
5.1.1.3 Ambient Tolerance ......................... 80
5.1.1.4 User-Friendliness ......................... 80
5.1.1.5 Ease of Interpretation .................... 80
5.1.1.6 Unique Capabilities ....................... 81
5.2 Technical Implementation .................................. 81
5.2.1 Spatial Positioning and Control .................... 81
5.2.2 The Feedback Control Electronics ................... 83
5.2.3 The Probe .......................................... 86
5.2.3.1 STM ....................................... 86
5.2.3.2 SFM ....................................... 87
5.2.3.3 SFM Probe Calibration ..................... 88
5.3 STM/STS ................................................... 90
5.3.1 Physical Principles - Brief Theory ................. 90
5.3.2 Operational Modes - STM ............................ 94
5.3.2.1 Imaging at Constant Tunnel Current ........ 94
5.3.2.2 Imaging at Constant Height ................ 94
5.3.2.3 Error Signal Mapping ...................... 94
5.3.2.4 I-V Spectroscopy .......................... 94
5.4 SFM ....................................................... 95
5.4.1 Physical Principles ................................ 96
5.4.2 SFM Operational Modes .............................. 97
5.4.2.1 AC Modes - Non-contact and Intermittent
Contact (Tapping) ......................... 97
5.4.2.2 LFM and Friction Loop Analysis ........... 100
5.4.2.3 F-d Analysis ............................. 100
5.5 SCM ...................................................... 110
5.5.1 Principles and Implementation ..................... 110
5.5.2 Capacitance Mapping ............................... 110
5.5.3 Mapping Differential Capacitance .................. 112
5.6 SNOM ..................................................... 113
5.6.1 Physical Principles ............................... 113
5.6.2 Technical Details ................................. 115
5.6.2.1 Shear-Force Detection .................... 115
5.6.2.2 Optical Fibre Probe ...................... 115
5.6.3 Operational Modes ................................. 115
5.6.3.1 Transmission Imaging ..................... 117
5.6.3.2 Fluorescence ............................. 117
5.6.3.3 Near-Field Raman Spectroscopy and
Mapping .................................. 118
5.6.4 Tip-Enhanced Raman Spectroscopy (TERS) ............ 118
5.6.4.1 Technical Implementation of TERS ......... 119
5.7 SECM ..................................................... 119
5.7.1 Physical Principles ............................... 120
5.7.2 Technical Details and Applications ................ 120
5.8 Scanning Kelvin Probe (SKP) .............................. 122
5.8.1 Effects of Electrostatic Interaction .............. 122
5.9 Scanning Ion Current Microscopy (SICM) ................... 126
5.10 Future Prospects ......................................... 127
5.10.1 Increased Spatial Resolution for SFM .............. 127
5.10.2 Single Atom Chemical Identification by AFM ........ 128
5.10.3 Faster Scan Rates ................................. 130
5.10.4 Greater Integration and Specialisation ............ 130
Appendix: Methods for Calibration of Normal Force
Constant, kN ............................................. 131
References ............................................... 132
Chapter 6 Techniques and Methods for Nanoscale Analysis of
Single Particles and Ensembles of Particles ................... 135
6.1 Introduction ............................................. 135
6.1.1 Particle Size ..................................... 136
6.2 Photon-Correlation Spectroscopy (PCS) or Dynamic
Light Scattering (DLS) ................................... 138
6.2.1 Theory ............................................ 139
6.2.3 Mie Theory of Scattering .......................... 144
6.2.4 DLS Instrumentation ............................... 145
6.3 Differential Centrifugal Sedimentation (DCS) ............. 147
6.3.1 The Basics of Differential Sedimentation .......... 147
6.3.2 DCS Instrument Design ............................. 148
6.4 Zeta Potential ........................................... 151
6.5 Differential Mobility Spectrometry (DMS) ................. 152
6.6 Surface Area Determination ............................... 152
6.6.1 Adsorption and Desorption at Surfaces ........... 154
6.6.2 Surface Area Measurement by the BET Method ........ 158
6.6.3 BET Particle Analysis and the Equivalent Sphere ... 161
6.7 Surface and Bulk Chemistry ............................... 161
6.7.1 Single Particle Analysis .......................... 161
6.7.2 Surface Chemistry of Particle Ensembles ........... 162
6.7.3 Wettability ....................................... 163
6.8 Overview - Choice of Technique(s) ........................ 164
Acknowledgements ......................................... 165
References ............................................... 166
SECTION II Applications
Chapter 7 C60 and Other Cage Structures ...................... 171
7.1 Introduction ............................................. 171
7.1.1 Euler's Theorem ................................... 171
7.1.2 The Fullerene Family .............................. 172
7.2 Characterization of Fullerenes and Fullerene Compounds ... 174
7.2.1 Characterization of Non-interacting C60 and
of Cn*60 Molecules ................................ 174
7.3 Endohedral Fullerenes .................................... 176
7.4 Fullerites ............................................... 181
7.5 Peapod - Fullerenes in CNT ............................... 185
References ............................................... 189
Chapter 8 Quantum Dots and Related Structures ................ 191
8.1 Introduction ............................................. 191
8.2 Particles in 2-D and 3-D Confinement ..................... 192
8.3 Synthesis Routes for Quantum Dots ........................ 197
8.3.1 Colloidal Nucleation and Growth ................... 199
8.3.2 Quantum Dots - Lithographic Methods ............... 200
8.3.3 Self-Assembled Quantum Dots on a Planar
Substrate ......................................... 200
8.4 Characterization of Quantum Dots ......................... 200
8.4.1 Structure, Topography, and Analytical
Information ....................................... 200
8.4.2 X-Ray Diffraction and Scattering Methods for
Ensembles - XRD, SAXS, and WAXS ................... 202
8.4.2.1 Characterization by XRD .................. 202
8.4.2.2 Small-Angle X-Ray Scattering (SAXS) of
Quantum Dots ............................. 203
8.5 Absorption and Photoluminescence Spectroscopy of
Quantum Dots ............................................. 205
8.5.1 Photoluminescence of Single Quantum Dots .......... 208
References ............................................... 213
Chapter 9 Carbon Nanotubes and Other Tube Structures ......... 215
9.1 Introduction ............................................. 215
9.2 Description of CNT Structure ............................. 215
9.3 Synthesis Routes ......................................... 218
9.3.1 Arc-Discharge and Laser Ablation .................. 218
9.3.2 Chemical Vapour Deposition (CVD) .................. 218
9.3.2 Purification of Raw Product from Synthesis
Routes ............................................ 219
9.4 Electronic Structure of Graphene and SWCNT ............... 219
9.4.1 Electronic Band Structure of Graphene ............. 220
9.4.2 Electronic Structure of SWCNTs .................... 221
9.5 General Characteristics of CNTs .......................... 223
9.6 Other Tube Structures .................................... 223
9.7 Characterization of Nanotubes ............................ 225
9.7.1 Topographical and Structural Characterization ..... 226
9.7.1.1 CNT ...................................... 226
9.7.1.2 Other Tube Structures .................... 231
9.7.2 Analysis of Nanotubes by SPM ...................... 234
9.7.3 Raman Spectroscopy of CNTs ........................ 238
9.7.4 Characterization of Electronic Structure .......... 245
9.7.4.1 EELS ..................................... 245
9.7.4.2 Luminescence Spectroscopy ................ 245
References ............................................... 250
Chapter 10 Nanowires .......................................... 253
10.1 Introduction ............................................. 253
10.2 Synthesis Routes ......................................... 253
10.2.1 Overview of the VLS Process ....................... 253
10.2.2 The Template Process .............................. 256
10.3 Characterization of Nanowires by SEM and ТЕМ ............. 258
10.4 Characterization of Nanowire Heterostructures ............ 259
10.5 Characterization Related to Potential Applications ....... 259
References ............................................... 269
Chapter 11 Graphene and Other Monolayer Structures ............ 271
11.1 Introduction ............................................. 271
11.2 Graphene Structure ....................................... 271
11.3 Summary of Electronic Structure .......................... 273
11.4 'Other 2-D Structures (Nanosheets) ....................... 273
11.5 Overview of Synthesis Routes ............................. 275
11.5.1 Mechanical Exfoliation ............................ 275
11.5.2 Liquid Phase Exfoliation .......................... 275
11.5.3 Epitaxial Growth .................................. 276
11.5.4 Nucleation and Growth of Graphene on SiC .......... 276
11.5.5 Catalyst Promoted Nucleation and Growth of
Graphene .......................................... 276
11.6 Structural Characterization .............................. 277
11.7 Raman Spectroscopic Characterization ..................... 281
11.8 Characterization of Electronic Structure ................. 282
References .................................................... 286
Chapter 12 Nanostructures - Strategic and Tactical Issues ..... 289
12.1 Thinking about Strategy .................................. 289
12.2 Thinking about Tactics ................................... 289
12.3 Strategic Issues ......................................... 290
12.3.1 Other Nanostructures .............................. 290
12.3.2 Characterization of Nanostructure Ensembles ....... 291
12.4 Preparation of Specimens for Characterization of
Nanostructures ........................................... 292
12.5 Ensemble Averages: Limitations ........................... 295
12.6 'Soft' Materials - Specimen Preparation .................. 295
12.7 Cleanliness .............................................. 295
12.8 User-friendliness ........................................ 296
12.9 Cost-Effectiveness ....................................... 297
Acknowledgements .............................................. 298
Appendix A: Preparation of Cross-Sectional Specimens by
the Focussed Ion Beam (FIB) Method ............................ 299
General Description ...................................... 299
Typical Instrument ....................................... 299
Specimen Preparation by FIB Methods ...................... 299
Advantages ............................................ 299
Disadvantages ......................................... 301
Details of FIB Methods ................................ 302
Appendix B: (Cryo)Microtomy and Other Methods for Specimen
Preparation of Soft Materials (e.g., Polymers and
Biomaterials) ............................................ 303
General Overview ...................................... 303
Typical Instrument .................................... 304
References ................................................ 305
Index ......................................................... 307
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