One-dimensional chains of dye molecules on ultrathin insulating films
Résumé
Linear chains of dye molecules on insulating thin films may become essential for the study of electronic and excitonic effects in quantum-confined molecular systems using scanning tunneling microscopy (STM) (1,2). However, until now, such linear chains on thin insulators have only been obtained by assembling molecules one by one using the STM tip, which strongly limits the field of possible investigations and hampers the potential applications in device technology. Here, we demonstrate the spontaneous growth of these linear chains via molecular self-assembly on insulating thin films (1 to 3 atomic layer thick) (3). This growth is particularly difficult due to the weak interactions between the adsorbed molecules and the insulating surface. In this work, we overcome this difficulty by using a prochiral molecule (quinacridone) and an ionic insulator (potassium chloride, KCl). Quinacridone was shown to self-assemble into homochiral hydrogen-bonded chains on metals (4). Additionally, quinacridone proved to be a unique model system for the study of current driven optical transitions at the sub-molecular scale (5). Here, we take advantage of the electrostatic interactions between the (partially charged) functional groups of quinacridone and the ions of the underlying KCl layer to stabilize the molecular chains (3). Using low-temperature STM in ultrahigh vacuum, we determine the molecular arrangement of these chains and their relation of epitaxy with the substrate.
REFERENCES
1. B. Doppagne et al, Phys. Rev. Lett. 118, 127401 (2017)
2. Y. Luo et al, Phys. Rev. Lett. 122, 233901 (2019)
3. R. Bretel et al, Phys. Rev. B 108, 125423 (2023)
4. N. Humberg et al, J. Phys. Chem. C 124, 24861 (2020)
5. S. Jiang et al, Phys. Rev. Lett. 130, 126202 (2023)
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Licence : CC BY NC SA - Paternité - Pas d'utilisation commerciale - Partage selon les Conditions Initiales
Licence : CC BY NC SA - Paternité - Pas d'utilisation commerciale - Partage selon les Conditions Initiales