SKM 2023 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 2: Organic Molecules on Inorganic Substrates I: Electronic, Optical and Other Properties I

O 2.2: Vortrag

Montag, 27. März 2023, 10:45–11:00, CHE 89

Complex rotational behavior of ground and excited molecular states — •Andreas Christ, Markus Leisegang, Patrick Härtl, and Matthias Bode — Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany

The high sensitivity of molecular rotors to the intricate molecule–substrate interaction leads to a large variety of their rotational behavior [1]. In some cases this interaction can even change for different rotational positions on a molecule’s rotation path. We have studied these dependencies for copper-phthalocyanine (CuPc) on Cu(111) by means of low-temperature scanning tunneling microscopy. In agreement with previous results [2,3], we find one ground state oriented along the high-symmetry axes of the substrate and two excited states tilted by ≈ ± 7^∘. A more detailed analysis reveals an exceptionally low threshold of ≈ 20 meV for rotations between these three stable states. Interestingly, the interaction of the molecule with the substrate and therefore the rotation rate varies significantly between the ground and the excited states due to their different molecular bending. Additionally, we find two adsorption positions, which slightly lift the degeneracy between the two excited states.

[1] D. Lensen et al., Soft Matter 8, 9053 (2012)
[2] J. Schaffert et al., Phys. Rev. B 88, 075410 (2013)
[3] S. Fremy-Koch et al., Phys. Rev. B 100, 155427 (2019)