10. 10. 2018

Jan Čechal (CEITEC VUT):
Real-time view on phase transitions of self-assembled molecular layers

Abstract:

Molecular self-assembly enables fabrication of organic layers with a tailored functionality with atomic precision. In general,
molecular-substrate systems can display several distinct molecular phases depending on the surface coverage, temperature and ratio
of individual components. In the seminar we will introduce a methodology to visualize phase transformations that are induced by
carboxylation (or deprotonation of carboxylic groups) of 4,4’ biphenyl dicarboxylic acid (BDA) on Ag(001) surface. The real-time
view on deprotonation driven phase transition by low energy electron microscopy (LEEM) complemented with diffraction (LEED),
scanning tunnelling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) provides a clear view on the reaction. The
combination of mesoscale view provided by real-time low energy electron microscopy (LEEM) with atomic scale imaging by scanning
probe microscopy is essential to ambiguously relate the distinct contrast in LEEM images and complex diffraction patterns with
molecular arrangements associated with observed molecular phases.