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O: Fachverband Oberflächenphysik

O 5: Poster Session I: Metal substrates I

O 5.4: Poster

Monday, March 1, 2021, 10:30–12:30, P

Inducing and Probing the Rotational Motion of a Single Carbon Monoxide Molecule — •Nicolas Néel and Jörg Kröger — Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany

The control and observation of reactants forming a chemical bond at the single-molecule level is a longstanding challenge in quantum physics and chemistry. Using a single CO molecule adsorbed at the apex of an atomic force microscope tip and a Cu(111) surface at bonding distances, the molecular rotational motion is induced by torques due to van der Waals attraction and Pauli repulsion. As a result, the vertical force exhibits a characteristic dip-hump evolution with the molecule-surface separation, which depends sensitively on the initial tilt angle the CO axis encloses with the microscope tip. The experimental force data are reproduced by model calculations that consider the CO rotational motion in a harmonic potential and the molecular orientation in the Pauli repulsion term of the Lennard-Jones potential.