Laboratoire de Physique et Chimie des Nano-objets

Date : 17/04/2014 à 13:30

Titre : Exploiting periodically rippled graphene for self-organized growth : from size-quantized nanoclusters to molecular self-assembly.

Intervenant : Muriel Sicot

Provenance : Institut Jean Lamour, CNRS/Université de Lorraine Vandœuvre-lès-Nancy, France

Salle : Salle de Séminaire - LPCNO

Résumé : Chemical vapor deposition on transition metals (TM) is a method which can produce high quality graphene (Gr) on a large scale. Due to its stiffness and lattice mismatch with the metallic surface, the graphene sheet exhibits a height modulation called moiré pattern of a period of about 2 nm [1]. This nanomesh can be used as a template for the growth of nanostructures arrays and 2D supramolecular assembly. The chemical interaction with the substrate can vary from strong (chemisorption) to weak (physisorption) depending on the chosen transition metal. Moreover, the Gr/TM systems allow intercalation of foreign species X (X= atoms, molecules) leading to complex Gr/X/TM interfaces. Therefore a subtle choice of the substrate and the intercalated material offers the possibility to tune the surface potential and therefore the adsorption sites allowing variation of the nanoparticles arrangements. Moreover, as molecular self-assembly at surfaces is governed by the balance between intermolecular and molecule/surface interaction, self assembly can be tuned by the right selection of the Gr/X/TM interfaces.
In this talk, I’ll illustrate the interface engineering of graphene on transition metals for the growth of nanoparticles arrays and molecular assembly by two examples. In a first part, I’ll talk about the graphene nanomesh on Rh(111), a study performed in Konstanz university. The possibility to use this template to grow magnetic nanoparticles (Co, Ni) arrays was investigated [2]. I’ll show that intercalation of Ni results in epitaxial nanoislands which size and shape is strongly influenced by the local spatial variation of the Gr-Rh bonding strength [2]. In a second part, I’ll talk about my current work at Jean Lamour Institute focusing on the Gr/Cu/Ir(111) system. I’ll show that supramolecular nanostructures can be generated on the Gr/Ir(111) surface and that Cu intercalation in the submonolayer range allows to create preferential adsorption areas for molecules (1,3,5-Tris(4-bromophenyl)benzene C24H15Br3).
In this work, structure and electronic properties were characterized by scanning tunneling microscopy/spectroscopy (STM/STS), X-ray and angle-resolved photoemission spectroscopies (XPS,ARPES).

[1] J. Wintterlin and M.-L. Bocquet, Surface Science 603 (2009) 1841 [2] M. Sicot et al, Applied Physics Letters 96 (2010) 093115 [3] M. Sicot et al., ACS Nano 6 (2012) 151