On Clusters and Clustering (eBook)

Front Cover 1
On Clusters and Clustering: From Atoms to Fractals 4
Copyright Page 5
Table of Contents 14
Random Materials and Processes 3
Preface 6
Foreword 8
Introduction 10
Part I: Small Atomic and Molecular Clusters: Production, Properties, and Electronic Structure 22
Chapter 1. The Structures and Vibrational Dynamics of Small Carbon Clusters 28
1.1 Introduction 28
1.2 Theoretical Background 28
1.3 New Techniques for IR and FIR Spectroscopy of Cn Clusters 31
1.4 IR and FIR Laser Spectroscopy of Carbon Clusters 32
1.5 Conclusions 41
Acknowledgements 42
References 42
Chapter 2. Carbon Clusters: The Synergism Between Theory and Experiment 44
2.1 Introduction 44
2.2 Carbon Clusters 45
2.3 Theoretical Approaches for Excited States 50
2.4 Conclusion 51
Acknowledgements 51
References 51
Chapter 3. Negative-Ion Photodetachment Studies of Small Silicon and Carbon Clusters 54
3.1 Introduction 54
3.2 Experimental Approach 55
3.3 Results and Discussion 57
3.4 Conclusions 64
Acknowledgements 65
References 65
Chapter 4. Chemical Reactivity and Electronic Structure of Silicon Microclusters 68
4.1 Introduction 68
4.2 The Tight-Binding Model 69
4.3 Structure of Si10 Clusters 69
4.4 Reactivity of Si30–Si45 Clusters 71
4.5 Photofragmentation of Large Silicon Clusters 74
4.6 Summary 76
Acknowledgements 77
References 77
Chapter 5. Ionization Potentials and Electron Affinities of Semiconductor Clusters from Charge Transfer Reactions 80
5.1 Introduction 80
5.2 Experimental 81
5.3 Results 82
5.4 Discussion 83
5.5 Conclusions 87
Acknowledgement 87
References 87
Chapter 6. Size Dependence of Metal Cluster Reactivity as a Probe of Chemical Reactions 90
6.1 Introduction 90
6.2 Methodology 90
6.3 Size Dependence of Stereochemical Specificity 91
6.4 Benzene Dehydrogenation Is there a Size-threshold?
6.5 Steric Effects due to Cluster Size 93
6.6 Size Dependence of Reactivity as a Monitor of Reaction Mechanisms in Multiple Reactions 94
6.7 Conclusions 96
Acknowledgements 96
References 96
Chapter 7. Chemistry Within Molecular Clusters 98
7.1 Introduction 98
7.2 Experimental Method 99
7.3 Stabilizing an Unstable Reagent within a Cluster 99
7.4 Stabilizing an Unstable Intermediate within a Cluster 100
7.5 Providing New Chemical Pathways 102
7.6 Future Directions 105
Acknowledgement 106
References 106
Chapter 8. Mass Spectrometric Investigations of Cluster Ions 108
8.1 Introduction 108
8.2 Production Methods and Magic Numbers: Bismuth Clusters 109
8.3 Heterogeneous Clusters: Bismuth/Antimony 112
8.4 Structures and Isomers: Carbon Clusters 113
8.5 Metal-Carbide Clusters 115
8.6 Conclusions 118
Acknowledgements 118
References 118
Chapter 9. The Third Form of Carbon 120
9.1 Introduction 120
9.2 Fullerenes—A Molecular Form of Pure Carbon 121
9.3 Bulk Production of Fullerenes 124
9.4 Properties of the Pure Material 125
9.5 Doping the Fullerenes 127
9.6 Fullerene Chemistry—A Carbon-Based Nanotechnology 136
Acknowledgements 138
References 138
Part II: Larger Clusters: "Phase Transitions" in Clusters,Growth, Aggregation, and the Road to Condensed Matter 142
Chapter 10. Quantum Molecular Dynamics Studies of the Structure and Dynamics of Metal Clusters 148
10.1 Introduction 148
10.2 Theoretical Methods for Studies of Cluster Dynamics 150
10.3 Calculations and Results 153
10.4 Summary, Conclusions, and Future Prospects 161
Acknowledgements 162
References 162
Chapter 11. Gas-Phase Cluster Dynamics: Clustering and Growth 164
11.1 Introduction 164
11.2 Dynamics of Clusters 166
11.3 Conclusions 176
Acknowledgement 176
References 176
Chapter 12. Hydrocarbon Clusters: Building Blocks for New Materials 178
12.1 Introduction 178
12.2 Theoretical and Computational Approach 179
12.3 Hydrocarbon Molecules 180
12.4 Interactions Near the Diamond-Vapor Interface 182
12.5 Cohesive Energy and Electron Affinity of C60 183
12.6 Summary and Discussion 185
Acknowledgements 185
References 185
Chapter 13. Two-dimensional Metallic Adlayers: Dispersion Versus Island Formation 188
13.1 Introduction 188
13.2 Model 189
13.3 Results 191
13.4 Summary and Conclusions 196
Acknowledgements 198
References 198
Chapter 14. Cluster-Assembled Interfaces 200
14.1 Introduction 200
14.2 Experimental Procedures 201
14.3 Metal Cluster Morphologies on Xe and on GaAs( 110) 201
14.4 Valence-Band Evolution for Cluster and Atom Deposition 203
14.5 Core-Level Lineshapes 204
14.6 Band Bending and Surface Fermi Level Movement 208
14.7 Conclusions 212
Acknowledgement 212
References 212
Chapter 15. Magnetic Structure of Clusters 214
15.1 Introduction 214
15.2 Experimental Apparatu 215
15.3 Magnetic Behavior of Cobalt Clusters 220
15.4 Magnetic Behavior of Gadolinium Clusters 224
15.5 Conclusions 228
Acknowledgements 229
References 229
Chapter 16. Supramolecular Particles: The Transition from the Molecular to the Solid State 230
16.1 Introduction 230
16.2 Magnetic Properties of Clusters 231
16.3 Two Experimental Test Systems 232
16.4 Conclusion 239
Acknowledgements 240
References 240
Chapter 17. A Mean-Field Theory of Melting for Microcrystals 242
17.1 Introduction 242
17.2 Formulation 242
17.3 Solutions and Results 244
17.4 Conclusion 246
Acknowledgement 247
References 247
Chapter 18. Cluster Simulations: Melting and Sintering 248
18.1 Introduction 248
18.2 Homogeneous Clusters: Review of Phase Changes 249
18.3 Homogeneous Clusters: Potentials and Structures 249
18.4 Homogeneous Clusters: Dynamics 253
18.5 Binary Clusters: Structures and Dynamics of (KCl)4 and (KCl)5 257
Acknowledgement 261
References 262
Chapter 19. Clusters and Nucleation 264
19.1 Introduction 264
19.2 Magnetic and Liquid-Gas Transitions 266
19.3 Theory of Nucleation near the Freezing Spinodal 269
19.4 Nature of the Nucleating Droplet 270
19.5 Monte Carlo Simulations of Nucleation 272
19.6 Nature of Clusters in Crystalline Nucleation 274
19.7 Summary 276
Acknowledgements 276
References 277
Chapter 20. Superfluidity in Helium Clusters 278
20.1 Introduction 278
20.2 Transition Temperatures 278
20.3 Collective Excitations 280
20.4 Detecting Superfluidity 282
20.5 Summary 284
Acknowledgements 285
References 285
Part III: Clusters in Condensed Matter and Fractal Behavior 288
Chapter 21. Assembly of Supra-Nanoclusters Within Crystalline and Amorphous 3-D Structures 294
21.1 Introduction 294
21.2 Current Synthetic Methodologies 295
21.3 Host-Guest Synthesis 299
21.4 Conclusions 304
Acknowledgements 304
References 305
Chapter 22. A Macroscopic Approach to Cluster-Assembled Materials 308
22.1 Introduction 308
22.2 The Separation of Time-Scales Approach 309
22.3 Detailed Description of the Models 312
22.4 Illustrative Example 320
22.5 Final Remarks 321
References 321
Chapter 23. Physical Properties of Granular Metal Solids 324
23.1 Introduction 324
23.2 Sample Preparation 325
23.3 Structure 325
23.4 Thermal Properties 328
23.5 Transport Properties 333
23.6 Magnetic Properties 336
23.7 Infrared Properties 339
Acknowledgements 339
References 341
Chapter 24. Fractal Structures and Dynamics of Cluster Growth 344
24.1 Introduction 344
24.2 Fractal Concepts 344
24.3 Percolation and Correlated Cluster Growth 348
24.4 Fractal Distribution of Clusters 349
24.5 Rough Surfaces: Self-affine Fractals 354
24.6 Fractal Patterns in Diffusive Growth 357
24.7 Viscous Fingering 358
24.8 Laplacian Fractals 359
24.9 Dendritic Solidification: Snow Crystals 360
24.10 Conclusions 362
References 363
Chapter 25. Disorderly Cluster Growth 366
25.1 Introduction 366
25.2 Cluster Growth Probabilities 366
25.3 "Void-Neck" Model of DLA Structure 368
25.4 Scaling Properties of the DLA Perimeter: The "Glove" Algorithm 370
25.5 Multiscaling 372
25.6 Summary 375
Acknowledgements 375
References 375
Chapter 26. Towards a Realistic General Continuum Theory of Clustering 378
26.1 Introduction 378
26.2 Continuum Potts Model 379
26.3 Connectedness Functions and the Percolation Threshold 382
26.4 A Scaled Particle Theory of Percolation 384
26.5 Cluster Size Distributions 386
26.6 Percolation and Ionic Clustering in Electrolytes 390
26.7 Conclusions 392
Acknowledgements 392
References 392
Chapter 27. Anomalous Diffusion in Disordered Clusters 394
27.1 Introduction 394
27.2 Random Walks on Percolation Clusters 395
27.3 Langevin Dynamics 398
27.4 Frequency-Dependent Transport 399
27.5 Summary and Discussion 402
Acknowledgements 402
References 402
Chapter 28. Frequency Dependent Electrical Conductivity of Mixed(Na+, Ba2+)/ß"-aIumina 404
28.1 Introduction 404
28.2 Extrapolated dc Conductivity 405
28.3 ac Conductivity 407
28.4 Summary and Conclusions 411
Acknowledgements 411
References 411
Chapter 29. Clustering and Relaxation in Condensed Matte 414
29.1 Introduction 414
29.2 Thermodynamic Model 414
29.3 Comparison with Experiments 416
29.4 Conclusions 420
Acknowledgements 421
References 421