| Autor: |
Granet, J., Sicot, M., Gerber, I. C., Kremer, G., Pierron, T., Kierren, B., Moreau, L., Fagot-Revurat, Y., Lamare, S., Chérioux, F., Malterre, D. |
| Zdroj: |
The Journal of Physical Chemistry - Part C; May 2020, Vol. 124 Issue: 19 p10441-10452, 12p |
| Abstrakt: |
We report on the formation of a two-dimensional supramolecular Kondo lattice made of organic molecules comprising only C, N, and H atoms, namely metal-free phthalocyanines 2HPc (C32H18N8), adsorbed on a Ag(111) surface. Low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/STS), ultraviolet photoemission spectroscopy (UPS), and density functional theory (DFT) are used to investigate the electronic structure of the system for low molecular density and commensurate self-assemblies. Abrikosov–Suhl resonances that are characteristic of the arising of a Kondo effect are observed by using both STS and UPS at low temperature. Whereas freestanding 2HPc is a no-spin-bearing molecule, it acquires an unpaired electron in its π-conjugated lowest unoccupied molecular orbital (LUMO) upon adsorption on Ag. As a result, the Kondo effect can be interpreted as originating from the interaction between this unpaired π-spin and the Ag Fermi sea. Extra side resonances are observed in STS spectra that are a manifestation of the coupling between the π electron and molecular vibrational excitations, qualifying the effect as the molecular vibrational Kondo effect. The variation of the Kondo temperature TKof single molecules and upon two-dimensional self-assembly is discussed. This study brings new insights into the Kondo-related physics in correlation with molecular spins and low dimensionality. Moreover, it may open new routes to the synthesis of organic molecular spintronic devices. |
| Databáze: |
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