Nanoparticles (eBook)

After degrees in Chemistry (BSc, 1986; MSc, 1990) from the State University of São Paulo (Brazil), Celso de Mello Donega moved to the Netherlands, where he worked under the supervision of Prof. George Blasse from 1991 to 1994, being awarded a PhD degree in Chemistry from Utrecht University in 1994. Upon his return to Brazil in 1995, he was appointed Associate Professor at the Federal State University of Pernambuco. He moved back to the Netherlands in 2000 to join the Condensed Matter and Interfaces Group of the Debye Institute for Nanomaterials Science at Utrecht University, where he currently holds a tenured Associate Professor position. His expertise is in the field of synthesis and optical spectroscopy of luminescent materials. His research is focused on the chemistry and optoelectronic properties of nanomaterials, with particular emphasis on colloidal nanocrystals and heteronanocrystals.

Preface 6
Contents 9
1 The Nanoscience Paradigm: ``Size Matters!'' 11
Abstract 11
1.1 What Is Different About the Nanoscale? 11
1.1.1 Finite Size Effects I: Spatial Confinement 12
1.1.2 Finite Size Effects II: 14
1.2 Nanomaterials: and Classification 15
1.2.1 What Are Nanomaterials? 15
1.2.2 Types 16
1.3 The Nanoscale Tool Box 17
1.3.1 Techniques to Make Nanoparticles 17
1.3.1.1 Bottom-up Approaches 17
1.3.2 Techniques to Study Nanoparticles 19
1.4 Exercises 21
References 21
2 Size Effects on Semiconductor Nanoparticles 23
Abstract 23
2.1 Introduction 23
2.2 Electronic Structure of Bulk Semiconductors 25
2.3 Electronic Transitions in Bulk Semiconductors 28
2.4 Electronic 31
2.4.1 : Nanocrystal as a Small Crystal 31
2.4.1.1 36
2.4.1.2 Shape Effects 37
2.4.2 Nanocrystal as a Large Molecule: Building Up Atom by Atom 38
2.5 Optical Transitions in a Semiconductor Nanoparticle 43
2.6 Exciton Relaxation and Recombination 46
2.7 Excitons in Semiconductor Heteronanostructures 50
2.8 Size Effects on the Electronic Structure of Nanocrystals: Semiconductors in Comparison to Metals 54
2.9 Applications of Semiconductor Nanoparticles 55
2.10 Outlook 58
2.11 Exercises 58
References 60
3 Metal Nanoparticles for Microscopy and Spectroscopy 62
Abstract 62
3.1 Introduction 62
3.2 The Optical Response of Bulk Metals 64
3.2.1 The Drude Model for a Free Electron Plasma 64
3.2.2 The Dielectric Function of Ag and Au in Reality 66
3.2.3 Comparison of Metals 67
3.3 Scattering by Small Particles 68
3.3.1 Polarizability of a Small 68
3.3.2 Extinction and Scattering Cross Sections 70
3.3.3 Spheroids 73
3.4 Applications of Single Metal Nanoparticles 75
3.4.1 Optical Detection of a Single Particle 76
3.4.2 A Metal Particle as an Optical Label 79
3.4.3 Optical Trapping 80
3.4.4 Biosensing 81
3.4.5 Emission Enhancements 84
3.5 Clusters and Lattices of Metal Nanoparticles 86
3.5.1 Plasmon Hybridization 87
3.5.2 Validating Plasmon Hybridization Intuition 90
3.5.3 Observation and Use of Dark Modes 92
3.5.4 Narrow Gaps Yield High Fields 93
3.5.5 96
3.5.6 Lattices of Plasmonic 99
3.6 Exercises 103
References 105
4 Nanoporous Materials and Confined Liquids 108
Abstract 108
4.1 Introduction 108
4.2 Classes of Nanoporous Materials 110
4.2.1 110
4.2.2 Metal-Organic and Organic Microporous Materials 113
4.2.3 Disordered Mesoporous 114
4.2.4 116
4.2.5 118
4.3 Liquids Confined in Nanopores 119
4.3.1 Wetting 120
4.3.2 Capillarity and Capillary Condensation 121
4.3.3 Gas Physisorption 124
4.3.4 Changes in Melting Behaviour 125
4.3.5 125
4.4 Outlook 127
4.5 Exercises 127
References 129
5 Supported Nanoparticles 130
Abstract 130
5.1 Preparation Strategies 130
5.1.1 Precursor Solution 132
5.1.2 134
5.1.3 135
5.2 Characterization 136
5.3 Supported Nanoparticles as Catalysts 138
5.3.1 140
5.3.2 Nanoparticle Stability 142
5.3.3 143
5.4 Nanomaterials for and Storage 144
5.4.1 Gas Separation 144
5.4.2 Reversible 146
5.5 Outlook 150
5.6 Exercises 150
References 152
6 The Challenge of Colloidal Nanoparticle Synthesis 153
Abstract 153
6.1 Introduction 153
6.2 Colloidal Nanoparticles: When the Whole Is Greater than the Sum of Its Parts 154
6.2.1 The Inorganic Core 155
6.2.2 The Organic Shell 156
6.2.3 The Organic& hx2013
6.3 Colloidal Nanoparticle Synthesis 162
6.3.1 Synthesis Methodologies 162
6.3.2 The Hidden Variable: Adventitious Impurities 166
6.3.3 Colloidal Nanoparticle Synthesis: Fundamental Concepts 167
6.3.3.1 : The Monomer Formation 170
6.3.3.2 Nucleation Stage 171
Homogeneous Nucleation 171
Sec13 175
6.3.3.3 177
Oriented Attachment and Shape Control 178
Growth by 179
Homoepitaxial 183
Heteroepitaxial Growth and Shape Control 188
6.4 Outlook 192
6.5 Exercises 193
References 193
7 Electron Microscopy Techniques 198
Abstract 198
7.1 Introduction: Imaging Nanoparticles with Electrons 198
7.2 Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) 199
7.2.1 201
7.3 Two Imaging 202
7.4 Electron Diffraction 204
7.5 Advanced Imaging---Contrast Modes 207
7.6 Electron Tomography: 3-Dimensional Imaging 211
7.7 Analytical EM: Chemical Mapping, EDX and 216
7.7.1 Energy-Dispersive 217
7.7.2 218
7.8 Cryo-TEM: Frozen-in Nanoparticles and Their Assemblies 220
7.9 In situ TEM: Gas Exposure and Heating 223
7.9.1 In Situ Gas Exposure 223
7.9.2 In Situ Heating 224
7.10 Outlook: Quantitative and Dynamic EM 225
7.11 Exercises 226
References 227
8 Scanning Probe Microscopy and Spectroscopy 229
Abstract 229
8.1 Introduction 229
8.2 Microscopy and Spectroscopy of Colloidal Quantum Dots 230
8.2.1 Why Perform Microscopy and Spectroscopy on Single Nanocrystals? 230
8.2.2 Scanning Tunneling Microscopy and the Double-Barrier Tunnel Junction 231
8.2.3 Electron-Electron Interactions in Nanocrystals 236
8.2.4 Comparison Between Optical and 238
8.2.5 Charge Sensing with Atomic Force Microscopy 239
8.2.6 Sample Preparation 241
8.3 Examples of Typical STM experiments with Nanocrystals 243
8.3.1 Electronic Structure of PbSe Nanocrystals 243
8.3.2 Measuring the Size of a Nanocrystal 244
8.3.3 Acquisition and Processing of Spectroscopic Measurements 245
8.3.4 Identification of the Transport Regime 246
8.3.5 248
8.3.6 Charge Sensing 250
8.3.7 Symmetry of the Energy Levels 253
8.3.8 Elastic or 253
8.3.9 Dot-in-Rod Heteronanocrystals 255
8.4 Exercises 256
Acknowledgments 258
References 258
9 Electron Paramagnetic Resonance Based Spectroscopic Techniques 262
Abstract 262
9.1 Fundamentals 262
9.1.1 Detected Electron Paramagnetic Resonance (ESE-EPR) 263
9.1.2 Electron-Nuclear Double Resonance (ENDOR) 264
9.1.3 Optically Detected Magnetic Resonance (ODMR) 264
9.2 Applications to Nanomaterials 265
9.2.1 ZnO Nanocrystals 266
9.2.1.1 The Identification of the Binding Core of Shallow Donors and Deep s in ZnO Nanocrystals by EPR and ENDOR 266
9.2.1.2 Probing the Wave Function of Shallow Donors in ZnO Nanocrystals and Confinement Effects 270
9.2.1.3 Dynamic Nuclear Polarization of Nuclear Spins in ZnO Nanocrystals 272
9.2.1.4 ODMR via in ZnO Nanocrystals 274
9.3 Outlook 275
9.4 Exercises 276
Acknowledgments 276
References 277
10 Solution NMR Toolbox for Colloidal Nanoparticles 278
Abstract 278
10.1 Introduction 278
10.2 One-Dimensional NMR Spectroscopy (1D NMR) 279
10.2.1 Exciting Spins 279
10.2.2 281
10.2.3 Quantification 282
10.3 Diffusion Ordered Spectroscopy (DOSY) 284
10.3.1 The Basics 284
10.3.2 286
10.3.3 in DOSY 287
10.4 288
10.4.1 Screening for Ligands 288
10.4.2 Recognizing Ligands in Fast Exchange 291
10.5 The Solution NMR Toolbox in Action: Octylamine Stabilized CdSe NPs 291
10.5.1 Octylamine Stabilized CdSe NPs 292
10.5.2 293
10.5.3 of Octylamine 294
10.6 Outlook 296
10.7 Exercises 296
References 297
Index 299