Submolecular charge distribution significantly affects the physical-chemical properties of molecules and their mutual interaction. One example is the presence of a π-electron-deficient cavity in halogen-substituted polyaromatic hydrocarbon compounds, the so-called π-holes, the existence of which was predicted theoretically, but the direct experimental observation is still missing. Here we present the resolution of the π-hole on a single molecule using the Kelvin probe force microscopy, which supports the theoretical prediction of its existence. In addition, experimental measurements supported by theoretical calculations show the importance of π-holes in the process of adsorption of molecules on solid-state surfaces. This study expands our understanding of the π-hole systems and, at the same time, opens up possibilities for studying the influence of submolecular charge distribution on the chemical properties of molecules and their mutual interaction.

Department of Physical Chemistry Palacký University Olomouc Tr 17 listopadu 12 771 46 Olomouc Czech Republic

Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences Flemingovo Námĕstí 542 2 16000 Prague Czech Republic

Institute of Physics Academy of Sciences of the Czech Republic Prague Czech Republic

IT4Innovations VŠB Technical University of Ostrava 17 Listopadu 2172 15 708 00 Ostrava Poruba Czech Republic

Regional Centre of Advanced Technologies and Materials Czech Advanced Technology and Research Institute Palacký University Olomouc 78371 Olomouc Czech Republic

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