Copper oxide functionalization of QPlus AFM tips allows imaging of molecular structures with extraordinary stability

ROM 2019-02
Author: Harry Moenig //
Institute: Physikalisches Institut Westfälische Wilhelms-Universität Münster // Center for Nanotechnology (CeNTech) // Heisenbergstr. 11 // D-48149 Münster
Instrument: LT STM

CeNTech scientists develop a method to visualize interactions between molecules with exceptional resolution in real-space. The method is based on low-temperature atomic force microscopy (AFM) and uses a copper-based probe tip, which is terminated by a single oxygen atom. The team around Dr. Harry Mönig, Dr. Saeed Amirjalayer and Prof. Harald Fuchs demonstrates the exceptional mechanical and chemical stability of this atomically defined probe tip. These properties allow a spatial resolution on the sub-molecular scale allowing to visualize the bonding structure of a hydrogen bonded molecular network. This study has been published in Nature Nanotechnology.

The new method can be used to image the structural and chemical properties of organic molecules with extreme precision. The experiment is based on QPlus atomic force microscopy where sample surfaces are scanned with the apex of a needle-like probe. As the lead author of the study Dr. Harry Mönig explains: "Our special technique involves a copper-based probe tip which is passivated by a single oxygen atom at the tip termination." Here, passivation means that the oxygen atom reduces undesired interaction between the atoms of the tip and the atoms in the molecules under investigation. This greatly increases the imaging resolution. In contrast to previous methods, the bond between the oxygen atom at the tip and copper base is particularly strong, thereby reducing imaging artefacts to a minimum.

Authors: Harry Mönig, Saeed Amirjalayer, Alexander Timmer, Zhixin Hu, Lacheng Liu, Oscar Díaz Arado, Marvin Cnudde, Christian Alejandro Strassert, Wei Ji, Michael Rohlfing and Harald Fuchs