The properties of novel and prospective 2D materials are dramatically influenced by the interaction with a substrate. For example, the electronic hybridization of silicene states on Ag(111) or graphene ones on Ni(111) disrupts the Dirac fermions of the freestanding layers. This calls for efficient approaches to tune the interaction strength at the interface. Here we focus on the case of graphene functionalized by organic molecules and grown on Ni(111) and on the interfacial charge transfer dynamics. This is investigated by X-ray resonant photoemission spectroscopy, that is able to measure electron transfer rates occurring within few femtoseconds, and by a theoretical framework based on density-functional theory [1,2]. We use 4,4’-bipyridine as the prototypical molecule for these explorations as the energy level alignment of core-excited molecular orbitals allows ultrafast injection (τ=4fs) of electrons from the substrate to the molecule adsorbed on epitaxial graphene/Ni(111), which is characterized by a strong hybridization between C and metal states. We demonstrate that this interface can be decoupled by the addition of a second layer of graphene, where the one in contact with the metal acts as a buffer layer and the one in contact with the molecule is less hybridized with Ni underneath. This decreases the charge transfer rates by about one order of magnitude and is seen in both theory and experiments. [1] G. Fratesi, C. Motta, M. I. Trioni, G. P. Brivio, and D. Sánchez-Portal, J. Phys. Chem. C 118 (2014) 8775 [2] D. Cvetko, G. Fratesi, G. Kladnik, A. Cossaro, G.P. Brivio, L. Venkataraman, and A. Morgante, Phys. Chem. Chem. Phys. 18 (2016) 22140
Using A Buffer Layer To Tune Electron Injection Dynamics At The Organic-graphene/metal Interface / A. Ravikumar, G. Kladnik, M. Muller, A. Cossaro, G. Bavdek, L. Patera, D. SANCHEZ PORTAL, L. Venkataraman, A. Morgante, G.P. Brivio, D. Cvetko, G. Fratesi. ((Intervento presentato al 6. convegno International Meeting on Silicene tenutosi a Synchrotron Soleil nel 2017.
Using A Buffer Layer To Tune Electron Injection Dynamics At The Organic-graphene/metal Interface
G. Fratesi
Ultimo
2017
Abstract
The properties of novel and prospective 2D materials are dramatically influenced by the interaction with a substrate. For example, the electronic hybridization of silicene states on Ag(111) or graphene ones on Ni(111) disrupts the Dirac fermions of the freestanding layers. This calls for efficient approaches to tune the interaction strength at the interface. Here we focus on the case of graphene functionalized by organic molecules and grown on Ni(111) and on the interfacial charge transfer dynamics. This is investigated by X-ray resonant photoemission spectroscopy, that is able to measure electron transfer rates occurring within few femtoseconds, and by a theoretical framework based on density-functional theory [1,2]. We use 4,4’-bipyridine as the prototypical molecule for these explorations as the energy level alignment of core-excited molecular orbitals allows ultrafast injection (τ=4fs) of electrons from the substrate to the molecule adsorbed on epitaxial graphene/Ni(111), which is characterized by a strong hybridization between C and metal states. We demonstrate that this interface can be decoupled by the addition of a second layer of graphene, where the one in contact with the metal acts as a buffer layer and the one in contact with the molecule is less hybridized with Ni underneath. This decreases the charge transfer rates by about one order of magnitude and is seen in both theory and experiments. [1] G. Fratesi, C. Motta, M. I. Trioni, G. P. Brivio, and D. Sánchez-Portal, J. Phys. Chem. C 118 (2014) 8775 [2] D. Cvetko, G. Fratesi, G. Kladnik, A. Cossaro, G.P. Brivio, L. Venkataraman, and A. Morgante, Phys. Chem. Chem. Phys. 18 (2016) 22140File | Dimensione | Formato | |
---|---|---|---|
Book_of_Abstracts-IMS-6__page20.pdf
accesso riservato
Descrizione: Abstract from the book of abstracts
Tipologia:
Publisher's version/PDF
Dimensione
691.61 kB
Formato
Adobe PDF
|
691.61 kB | Adobe PDF | Visualizza/Apri Richiedi una copia |
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.