Structure and dynamics of large moleculare adsorbates and self assembled organic template layers

The project B11 focuses on the process of structure formation in two-dimensional (2D) adlayers that either consist only of large organic molecules or of large organic molecules interlinked by separately deposited metal atoms. Goal is a detailed understanding of the dynamic processes on molecular scale such as the formation and decay of 2D nuclei, their extension towards long-range ordered adlayers, and the quantitative description of these processes and of the resulting structures in a comprehensive energetic and kinetic concept.

The project splits into two parts, where the first one mainly deals with the dynamic processes themselves and aims at a detailed analysis of the underlying molecule-molecule and molecule-substrate interactions. As main analytic instrument we utilize (time resolved) scanning tunneling microscopy (STM) at variable temperatures, partially complemented by low energy electron diffraction (LEED) and thermal desorption or vibrational spectroscopy. As molecular building blocks we mainly use Oligopyridines synthesized in project A7, which due to their structure and the anisotropy of their mutual interactions (hydrogen bonds) form a high versatility of structures. By systematic variation of substrate and molecule structure we want to develop a coherent concept of the molecule-molecule and molecule-substrate interaction energies and resulting energy barriers. These are compared to the results of ab-initio and force field calculations by cooperating theory groups. The molecular scale concepts describing the structure formation will also be verified in kinetic Monte Carlo simulations.

Main topic of the second part of the project are metal organic structures, where in addition to a quantitative description of structure formation and underlying energetics also the electronic and chemic properties of the metal centers are of particular interest. Those are probed by spectroscopic measurements and the adsorption of additional molecules.