STM Investigation of Molecular Architectures of Porphyrinoids on a AG(111) Surface: Supramolecular Ordering, Electronic Properties and Reactivity (Paperback, 2010)

1 Introduction ...................................................................................................... 1 2 Fundamentals .................................................................................................... 5 2.1 Principle of the STM ............................................................................................ 5 2.2 Origin of the Tunneling Current ........................................................................... 7 2.3 Scanning Tunneling Spectroscopy ...................................................................... 10 2.4 Contrast Mechanism of Molecular Adsorbates ................................................... 13 2.5 Temperature Programmed Desorption ................................................................ 16 2.6 Low Energy Electron Diffraction ....................................................................... 18 3 Experimental Setup ........................................................................................ 21 3.1 UHV System ...................................................................................................... 21 3.2 Scanning Tunneling Microscope ........................................................................ 23 3.3 Control Electronics and Vibration Isolation ........................................................ 26 3.4 Ag(111) ............................................................................................................. 28 3.5 Porphyrinoids..................................................................................................... 30 3.6 Preparation of thin Porphyrinoid Layers ............................................................. 33 3.7 Vapor-deposition of Cobalt and Iron .................................................................. 34 4 Results ............................................................................................................. 39 4.1 Self-Assembly and Individual Appearance of Tetraphenylporphyrins on Ag(111) ............................................................................................................. 41 4.1.1 Epitaxial growth ........................................................................................... 43 4.1.2 Appearance and Intramolecular Conformation .............................................. 48 4.1.3 Ordering Aspects.......................................................................................... 50 4.2 Self-Assembly and Individual Appearance of Cobalt(II)-Tetrakisditertbutylphenylporphyrins on Ag(111) ......................................................................... 61 4.2.1 Polymorphism of CoTTBPP ......................................................................... 62 4.2.2 Polarity-Dependent Appearance ................................................................... 78 ii Table of Contents 4.3 Coordination of Iron and Cobalt Atoms by Tetraphenylporphyrin Monolayers on Ag(111) and Formation of Metal(II)-Tetraphenylporphyrin ......... 83 4.3.1 Coordination of Post-deposited Iron Atoms by Tetraphenylporphyrin Monolayers ................................................................................................... 85 4.3.2 Coordination of Pre-deposited Iron Atoms by Tetraphenylporphyrin Monolayers ................................................................................................... 90 4.3.3 Coordination of Post-deposited Cobalt Atoms by Tetraphenylporphyrin Monolayers ................................................................................................... 94 4.3.4 Discussion of the Metalation Reaction .......................................................... 99 4.4 Different Aspects of 2H-Tetrakisditertbutylphenylporphyrin on Ag(111) .. 103 4.4.1 Monolayer Preparation................................................................................ 104 4.4.2 Arrangement of 2HTTBPP .........................................