Metal Clusters at Surfaces: Structure, Quantum Properties, Physical Chemistry

ISBN-13: 9783642630644 / Angielski / Miękka / 2012 / 310 str.

Karl-Heinz Meiwes-Broer

Opis

Numerous experiments and calculations have shown that isolated metal clusters possess many interesting features, quite different from those known from surface and solid- state physics or from atomic and molecular physics. The technological exploitation of these new properties, e.g. in miniature electronic or mechanical components, requires the cluster to be brought into an environment such as an encapsulating matrix or a surface. Due to the interaction with the contact medium, the properties of the clusters may change or even disappear. Thus the physics of cluster-on-surface systems -- the main subject of this book -- is of fundamental importance. The book addresses a wide audience, from the newcomer to the expert. Starting from fundamental concepts of adsorbate-surface interactions, the modification of electronic properties through electron confinement, and concepts of cluster production, it elucidates the distinct properties of the new metallic nanostructures.

Spis treści

1 Confinement and Size Effects in Free Metal Clusters.- 1.1 Introduction.- 1.2 Free Simple Metal Clusters.- 1.2.1 The Shell Model.- 1.2.2 Extended Theoretical Models.- 1.2.3 Liquid and Solid Clusters.- 1.2.4 Molecular Beam Methods for Cluster Research.- 1.2.5 Electronic and Geometrical Structure.- 1.2.6 Optical Excitations and Plasma Resonances.- 1.3 Magnetic Particles in Molecular Beams.- 1.3.1 Stern-Gerlach Deflections of Ferromagnetic Metal Clusters.- 1.3.2 Magnetic Moments of 3d Transition Metal Clusters.- 1.3.3 Other Ferromagnetic Cluster Systems.- 1.4 Conclusion.- 2 Fundamentals of Adsorbate-Surface Interactions.- 2.1 Introduction.- 2.2 Physisorption of Xenon on Graphite: Superstructure and Domain Boundaries.- 2.3 Chemisorption of Alkali Atoms on Semiconductor Surfaces.- 2.3.1 Ionic vs. Covalent Bonding and Charge-Transfer Monitoring.- 2.3.2 Li, Na, K and Cs on Cleaved Si(111).- 2.3.3 Li, Na, K and Rb on Si(100).- 2.4 Bonding of C60 Molecules on Ag and Au(110) Surfaces.- 2.4.1 Geometric Properties.- 2.4.2 Electronic Properties.- 2.5 Electronic Response within the Cluster-Surface Interaction.- 2.6 Summary.- 3 Growth of Metal Clusters at Surfaces.- 3.1 Introduction.- 3.2 The Elementary Processes of MBE Growth.- 3.3 Nucleation.- 3.4 Aggregation.- 3.5 Coarsening.- 3.6 Anisotropic Surfaces.- 3.7 Growth of Cluster Arrays.- 3.8 Single Crystal Oxide Surfaces.- 3.9 Conclusion.- 4 Collision of Clusters with Surfaces.- 4.1 Introduction.- 4.2 Cluster-Surface Collisions: General Remarks.- 4.3 Experimental Considerations.- 4.4 Molecular Dynamics Calculations.- 4.5 Softlanding..- 4.6 Fragmentation.- 4.6.1 Clusters Scattering off the Surface.- 4.6.2 Fragmentation Studies on Molecules and Clusters.- 4.7 Implantation.- 4.8 Sputtering.- 4.9 Thin Film Formation by Energetic Cluster Impact.- 4.10 Cluster Impact Chemistry.- 4.11 Crater Formation and Cluster Impact Induced Erosion.- 4.12 Electronic Processes.- 4.13 Summary and Outlook.- 5 Electronic Level Structure of Metal Clusters at Surfaces.- 5.1 Introduction.- 5.2 Photoelectron Spectroscopy of Deposited Clusters.- 5.3 Scanning Tunnelling Spectroscopy and Inverse Photoemission.- 5.3.1 Target Preparation and Experimental Methods.- 5.3.2 STS on Platinum, Silver and Sodium Clusters.- 5.3.3 Photon Maps of Silver Islands.- 5.4 Summary.- 6 Conductance Quantisation in Metallic Point Contacts.- 6.1 Introduction.- 6.2 Landauer Theory for Ballistic Conductance.- 6.3 Experimental Techniques.- 6.4 Conductance of Atomic-Scale Contacts.- 6.5 Histograms of Conductance Values.- 6.6 The Character of the Conductance Modes Through a Single Atom.- 6.6.1 Subgap Structure in Superconducting Contacts.- 6.6.2 Valence-Orbital-Based Description of the Conductance Modes.- 6.6.3 Further Experimental Techniques.- 6.6.4 Implications for Conductance Curves and Histograms.- 6.7 Chains of Atoms.- 6.8 Quantum Forces and Shell Structure in Alkali Nanowires.- 6.9 Discussion and Outlook.- 7 Magnetism of Nanometer-Sized Particles and Clustersr.- 7.1 Introduction.- 7.2 Single Particle Measurement Techniques.- 7.2.1 Micro-SQUID Magnetometry.- 7.3 Mechanisms of Magnetisation Reversal in Single Domain Particles at Zero Kelvin.- 7.3.1 Magnetisation Reversal by Uniform Rotation.- 7.3.2 Generalisation of the Stoner-Wohlfarth Model.- 7.3.3 Experimental Verification.- 7.4 Influence of Temperature on Magnetisation Reversal.- 7.4.1 Superparamagnetism — Néel-Brown Model.- 7.4.2 Experimental Methods.- 7.4.3 Experimental Evidence for the Néel-Brown Model.- 7.5 Magnetisation Reversal by Quantum Tunnelling.- 7.5.1 Molecular Clusters.- 7.5.2 Individual Single-Domain Nanoparticles.- 7.5.3 Single-Domain Nanoparticles and Wires at Low Temperatures.- 8 Physical Chemistry of Supported Clusters.- 8.1 Introduction.- 8.2 Supported Size-Distributed Model Catalysts.- 8.2.1 Preparation and Characterisation.- 8.2.2 CO Dissociation on Supported Rh Clusters.- 8.2.3 Kinetic Effects in the CO Oxidation Reaction on Supported Pd Particles.- 8.2.4 Catalytic Activity of Supported Au Clusters.- 8.3 Supported Monodispersed Model Catalysts.- 8.3.1 Preparation and Characterisation of Monodispersed Supported Clusters.- 8.3.2 Size-Dependent CO Dissociation on Small Ni Clusters.- 8.3.3 The Catalytic Role of Small Silver Clusters for the Latent Image Generation in Photography.- 8.3.4 The Hydrogenation of Toluene on Monodispersed Ir4 and Ir6 Supported on Oxide Surfaces.- 8.3.5 Size-Dependent Cyclotrimerisation of Acetylene on Monodispersed Palladium Clusters Supported on MgO.- 8.3.6 The Oxidation of CO on Monodispersed Platinum Clusters Supported on MgO.- 8.3.7 The Oxidation of CO on Monodispersed Gold Clusters Supported on MgO.- 8.4 Conclusions and Outlook.- 9 Application of Clusters to the Fabrication of Silicon Nanostructures.- 9.1 Prospects for the Application of Clusters.- 9.1.1 Clusters as Building Blocks.- 9.1.2 Clusters as Tools.- 9.2 Silicon Nanostructures.- 9.2.1 Motivation.- 9.2.2 Experimental Approaches.- 9.3 Production of Cluster Films for Fabrication.- 9.3.1 Cluster Growth on Surfaces.- 9.3.2 Deposition of Size-Selected Clusters.- 9.3.3 Organised Arrays of Clusters.- 9.4 Application of Metal Clusters as Plasma Etching Masks.- 9.4.1 Fabrication of Silicon Pillars and Cones using Cluster Films Grown on the Surface.- 9.4.2 Production of Silicon Pillars Using Cluster Beam Deposition.- 9.4.3 Ordered Arrays of Silicon Pillars.- 9.5 Summary.

O autorze

The book addresses a wide audience, from the beginner in this field to the expert. Starting from fundamental concepts of adsorbate - surface interactions, the modification of electronic properties through electron confinement as well as concepts of cluster production, the book will deal with very distinct properties of the new metallic nanostructures.