NCAFM2023 Programme Booklet

Tuesday 1400 - 1420

THE STABILITY OF A STANDING MOLECULE AND ITS CAUSE

Marvin Knol 1 , Hadi H. Arefi 1 , Daniel Corken 2 , James Gardner 2 , F. Stefan Tautz 1 , Reinhard J. Maurer 2 , Christian Wagner 1,*

1 Peter Grünberg Institut (PGI-3) Forschungszentrum Jülich, 52425 Jülich, Germany 2 Department of Chemistry, University of Warwick, Gibbet Hill Road, CV4 7AL Coventry, UK Email: c.wagner@fz-juelich.de

Molecular nanofabrication with the SPM is a fascinating way to create functional molecular structures and devices which do not form spontaneously. With the recent creation of an isolated standing molecule (Fig.), the third dimension perpendicular to the surface has become accessible to this technique [1]. Here, we discuss the aspect of mechanical stability which is crucial for such structures and show that standing PTCDA (perylene-tetracarboxylic dianhydride) is not only a gateable molecular quantum dot [2] and a single electron field emitter [1], but also a tunable GHz oscillator [3], making it a fascinating component in the toolbox of quantum nanoscience. Specifically, we have performed SPM experiments in which we map the tip-molecule interaction (Fig.) and measure the thermal stability of standing PTCDA at different temperatures and combine them with ab initio potential energy calculations. We find a remarkable agreement between the measured and calculated stabilization potentials, with deviations in the range of a few meV. The calculations thus confirmed reveal a generic stabilization mechanism, namely a fine balance between covalent and van der Waals interactions, including the long-range screening of the latter by many-body effects. We translate our results into a simple set of universal, intuitive design principles that could promote the future nanofabrication of a wide range of metastable molecular systems with the SPM.

Fig. Sections of the tip-molecule interaction energy Etm along the molecular plane of PTCDA (left) and perpendicular to it (right). Maps and PTCDA models are drawn and located to scale.

References [1] T. Esat, N. Friedrich, F. S. Tautz, R. Temirov, Nature, 2018, 558 , 573. [2] C. Wagner, M. F. Green, M. Maiworm, P. Leinen, T. Esat, N. Ferri, N. Friedrich, R. Findeisen, A. Tkatchenko, R. Temirov, F. S. Tautz, Nat. Mater., 2019, 18 , 853. [3] M. Knol, H. H. Arefi, D. Corken, J. Gardner, F. S. Tautz, R. J. Maurer, C. Wagner, Sci. Adv., 2021, 7 , eabj9751.

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