Thermally activated processes and electronic properties of size selected Ag clusters and grown metal islands on C_1tn6_1tn0 functionalized surfaces [Elektronische Ressource] / Stefanie Duffe

Stefanie Duffe

Sujets

• Physik

Informations

• Publié par: technischen_universitat_dortmund
• Publié le: 01 janvier 2009
• Nombre de lectures: 34
• Langue: English
• Poids de l'ouvrage: 22 Mo

Extrait

Thermally activated processes
and electronic properties
of size selected Ag clusters
and grown metal islands
on C functionalized 60
surfaces


Dissertation


Zur Erlangung des Doktorgrades der
Naturwissenschaften Naturwissenschaften
vorgelegt von


STTEEFFAANNIIEE DUUFFFFEE S D


angefertigt am
Lehrstuhl Experimentelle Physik I
der Fakultät Physik der Technischen Universität Dortmund

März 2009






























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TABLE OF CONTENTS

1 INTRODUCTION.......................................................................................................... 7
2 CLUSTERS AND FULLERENES.................................................................................. 11
2.1 Clusters 11
2.1.1 Size selected clusters 12
2.1.2 Electronically magic clusters 12
2.1.3 Geometrically magic clusters 16
2.1.4 Free Clusters 19
2.1.5 Examples for clusters on surfaces: catalysis 20
2.2 Fullerenes 23
2.2.1 The Buckminster fullerene C 24 60
2.2.2 The C fullerene 25 58
3 EXPERIMENTAL SETUP ........................................................................................... 27
3.1 The cluster deposition machine 28
3.1.1 The magnetron sputter gas aggregation source 28
3.1.2 The acceleration chamber 30
3.1.3 The mass selector 31
3.1.3.1 Mass resolution and error tolerance 33
3.2 The surface science facility 38
3.2.1 The C evaporator 39 60
3.2.2 The evaporator with integrated flux monitor 40
4 EXPERIMENTAL TECHNIQUES ................................................................................ 43
4.1 Scanning tunneling microscopy 43
4.2 Scanning tunneling spectroscopy 46


4.3 Ultraviolet photoelectron spectroscopy 48
5 SAMPLE PREPARATION............................................................................................51
5.1 Sample substrate preparation 51
5.1.1 Preparation of the HOPG substrate 51
5.1.2 Preparation of the Au(111)/mica substrate 52
5.1.3 Preparation of the silver single crystal 53
5.2 Preparation of the fullerene layer 53
5.2.1 Preparation of the C layer 54 60
5.2.1.1 Evaporation of C on Au(111) 54 60
5.2.1.2 Evaporation of C on HOPG 55 60
5.2.2 Preparation of the C layer 57 58
5.3 Ag cluster and metal island deposition 59
5.3.1 Deposition of size selected Ag clusters 59
5.3.1.1 Adjustment of the selectable Ag cluster mass 59
5.3.1.2 Cluster current and deposition time 61
5.3.1.3 Distribution and diffusion of deposited clusters 62
5.3.1.4 Soft landing of size selected Ag clusters 63
5.3.2 Growth mechanism of metal islands 64
6 RESULTS AND DISCUSSION ......................................................................................67
6.1 Height measurement and calibration 67
6.1.1 Data analyzing 67
6.1.2 Calibration of the z-piezo of the STM 67
6.1.3 Step edges and lattice constant of Au(111) 70
6.2 Properties of fullerene layers on surfaces 71
6.2.1 C /HOPG 72 58
6.2.2 C /HOPG 74 60
6.2.3 C /Au(111) 79 60
6.3 Thermally activated processes of size selected Ag clusters 83
6.3.1 Decay vs. stability of geometrically magic Ag clusters 84
2
6.3.1.1 Ag (N=55, 309, 561) / 1 ML C / Au(111) 84 N 60
6.3.1.2 Ag (N=147, 309) / 1 and 2 ML C / Au(111) 93 N 60
6.3.1.3 The´magic` metastable cluster size 100
6.3.1.4 Molecular dynamics and atomistic calculations 101
6.3.1.5 Ag (N=147, 309, 923) / 1 and 2 ML C / HOPG 104 N 60
6.3.1.6 Overview about the results of geometrically magic Ag clusters 110
6.3.2 Ostwald ripening of geometrically non-magic Ag clusters 111
6.3.2.1 Ag (N=68, 80) / 1 and 2 ML C / Au(111) 111 N 60
6.4 Thermally activated processes of grown metal islands 117
6.4.1 Ag islands on C / Au(111) 117 60
6.4.1.1 Calibration of the Ag EFM 117
6.4.1.2 0.026 ML Ag / 1.3 ML C / Au(111) 119 60
6.4.1.3 0.5 ML Ag / 1.3 ML C / Au(111) 121 60
6.4.1.4 4 ML Ag / 1.3 ML C / Au(111) 126 60
6.4.1.5 Calculation of the effective coverage 127
6.4.2 Pb islands on C / Au(111) 129 60
6.4.3 Comparison: Size selected Ag clusters vs. grown metal islands 133
6.5 STS spectra of size selected Ag clusters 134
6.5.1 STS spectra of Ag and Ag /C /HOPG 134 309 923 60
6.6 UPS spectra of size selected Ag clusters 147
6.6.1 UPS of Ag and Ag /C /HOPG 147 55 923 60
6.6.2 UPS of Ag and Ag /HOPG 149 55 923
7 SUMMARY AND OUTLOOK ..................................................................................... 155
7.1 Summary 155
7.1.1 Setup, sample systems 155
7.1.2 Softlanding, thermal stability 156
7.1.3 Spectroscopy 158
7.2 Outlook 158
8 APPENDIX .............................................................................................................. 161
3
8.1 Overview about deposition parameters and annealing steps 161
8.1.1 Deposition of Ag / C / Au(111) 161 N 60
8.1.1.1 Deposition of Ag / 1 ML C / Au(111) 161 55 60
8.1.1.2 Deposition of Ag / 1 ML C / Au(111) 161 309 60
8.1.1.3 Deposition of Ag / 1 ML C / Au(111) 162 561 60
8.1.1.4 Deposition of Ag / 1.3 ML C / Au(111) 163 147 60
8.1.1.5 Deposition of Ag / 1.7 ML C / Au(111) 163 309 60
8.1.1.6 Deposition of Ag / 1.2 ML C / Au(111) 164 68 60
8.1.1.7 Deposition of Ag / 1.1 ML C / Au(111) 165 80 60
8.1.2 Deposition of Ag / C / HOPG 165 N 60
8.1.2.1 Deposition of Ag / C / HOPG 165 147 60
8.1.2.2 Deposition of Ag / C / HOPG 166 309 60
8.1.2.3 Deposition of Ag / C / HOPG 166 923 60
8.1.3 Deposition of Ag / HOPG 167 N
8.1.3.1 Deposition of Ag / HOPG 167 55
8.1.3.2 Deposition of Ag / HOPG 167 923
8.1.4 Growth of metal islands / C / Au(111) 168 60
8.1.4.1 Growth of 0.026 ML Ag / 1.3 ML C / Au(111) 168 60
8.1.4.2 Growth of 0.5 ML Ag / 1.3 ML C / Au(111) 168 60
8.1.4.3 Growth of 4 ML Ag / 1.3 ML C / Au(111) 169 60
8.1.4.4 Growth of 0.04 ML Pb / 1 ML C / Au(111) 170 60
9 REFERENCES..........................................................................................................171
10 PUBLICATIONS ...........................................................................................195
11 GLOSSARY..................................................................................................197
12 ACKNOWLEDGMENTS ................................................................................199




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