Dr. Grażyna Antczak

Wroclaw, Poland
Grażyna Antczak received her Ph.D. from UWr in 2002. 2002-2008 was a postdoctoral researcher at the University of Illinois at Urbana-Champaign in the group of Gert Ehrlich. 2008-2010 she was a Humboldt Scholar at the Leibniz Universität Hannover in the group of Karina Morgenstern. She habilitated in 2011 at the UWr. Her research focuses on the study of organic-metal interfaces and the interplay between structural and electronic properties of thin molecular films on metallic surfaces. Currently she collaborate with Nika Spiridis at the Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences and with Thorsten Wagner at the JKU Linz.

Talk title: Identification of chirality of the organic molecular domains in the reciprocal space
The properties of the molecule-substrate interface are important for the performance of devices with an active layer of organic molecules. By co-adsorption of different organic molecules, so called bimolecular or binary monolayers are formed, which have interesting properties such as modulation of charges at the interface on the nm scale. In our study, we focus on the molecular layer composed of phthalocyanines adsorbed on the metallic surface. Phthalocyanine (Pc) molecules are a group of molecules that have been intensively studied due to their interesting properties for applications in optoelectronics. We study the combination of phthalocyanines by mixing molecules on the surface with opposite influence on the work function of the substrate. For this we use low energy electron microscopy (LEEM). The subject of this talk are the bimolecular domains composed of cobalt phthalocyanine (CoPc) and perfluorinated copper phthalocyanine (F₁₆CuPc) adsorbed on Ag(100) surfaces at room temperature and subsequently annealed at 470 K. The CoPc up to monolayer coverage decreases the work function of the silver surface while F₁₆CuPc increases it. Due to the electrostatic interaction between the partially negatively charged fluorine atoms of F₁₆CuPc and the partially positively charged hydrogen atoms of the CoPc, the first monolayer of the mixed phase in a 1:1 ratio is arranged in a checkerboard-like superstructure [1]. The individual phthalocyanine (Pc) molecules are adsorbed in this molecular structure in such a way that their molecular axis is rotated by 27^o with respect to the <011> directions of the substrate [2, 3]. This leads to the development of two mirror domains with opposite chirality. In this talk we will show that the structure factor of the constituent molecules allows the identification of these domains using the micro-diffraction mode (µLEED) of the LEEM apparatus. Furthermore, when the µLEED mode is applied to the dilute 2D molecular gas formed by about 0.5 ML of F₁₆CuPc on the surface, it allows a direct imaging of the molecular structure factor and, hence, the identification of the adsorption geometry of the molecule.