title: Covalent Functionalization by Cycloaddition Reactions of Pristine Defect-Free Graphene.
abstract: Based on a low-temperature scanning tunneling microscopy study, we present a direct visualization of a cycloaddition reaction performed for some specific fluorinated maleimide molecules deposited on graphene. Up to now, it was widely admitted that such a cycloaddition reaction can not happen without pre-existing defects. However, our study shows that the cycloaddition reaction can be carried out on a defect-free basal graphene plane at room temperature. In the course of covalently grafting the molecules to graphene, the sp2conjugation of carbon atoms was broken, and local sp3bonds were created. The grafted molecules perturbed the graphene lattice, generating a standing-wave pattern with an anisotropy which was attributed to a (1,2) cycloaddition, as revealed by T-matrix approximation calculations. DFT calculations showed that while both (1,4) and (1,2) cycloadditions were possible on free-standing graphene, only the (1,2) cycloaddition could be obtained for graphene on SiC(0001). Globally averaging spectroscopic techniques, XPS and ARPES, were used to determine the modification in the elemental composition of the samples induced by the reaction, indicating an opening of an electronic gap in graphene.
authors.affiliation: Institut de Sciences des Matériaux de Mulhouse, CNRS-UMR 7361, Université de Haute Alsace , 3Bis, rue Alfred Werner, Mulhouse 68093, France.
authors.forename: Lakshya
authors.initials: L
authors.lastname: Daukiya
authors.affiliation: Nanosciences group, CEMES CNRS-UPR 8011 , 29 Rue Jeanne Marvig, BP 94347, Toulouse 31055, France.
authors.forename: Cristina
authors.initials: C
authors.lastname: Mattioli
authors.affiliation: Institut de Sciences des Matériaux de Mulhouse, CNRS-UMR 7361, Université de Haute Alsace , 3Bis, rue Alfred Werner, Mulhouse 68093, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Aubel
authors.affiliation: Institut de Sciences des Matériaux de Mulhouse, CNRS-UMR 7361, Université de Haute Alsace , 3Bis, rue Alfred Werner, Mulhouse 68093, France.
authors.forename: Samar
authors.initials: S
authors.lastname: Hajjar-Garreau
authors.affiliation: Institut de Sciences des Matériaux de Mulhouse, CNRS-UMR 7361, Université de Haute Alsace , 3Bis, rue Alfred Werner, Mulhouse 68093, France.
authors.forename: François
authors.identifier: 0000-0002-2219-5086
authors.initials: F
authors.lastname: Vonau
authors.affiliation: Institut de Sciences des Matériaux de Mulhouse, CNRS-UMR 7361, Université de Haute Alsace , 3Bis, rue Alfred Werner, Mulhouse 68093, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Denys
authors.affiliation: Physikalisches Institut, Universität Freiburg , Hermann-Herder-Strasse 3, Freiburg 79104, Germany.
authors.forename: Günter
authors.initials: G
authors.lastname: Reiter
authors.affiliation: Department of Physics and Astronomy, Uppsala University , Box 516, Uppsala SE-751 21, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Fransson
authors.affiliation: Ecole Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie , Pasteur, 24, rue Lhomond, Paris 75005, France.
authors.forename: Elsa
authors.initials: E
authors.lastname: Perrin
authors.affiliation: Ecole Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie , Pasteur, 24, rue Lhomond, Paris 75005, France.
authors.forename: Marie-Laure
authors.identifier: 0000-0001-7122-4907
authors.initials: ML
authors.lastname: Bocquet
authors.affiliation: Institut de Physique Théorique, CEA/Saclay , Orme des Merisiers, Gif-sur-Yvette Cedex 91190, France.|Laboratoire de Physique des Solides, CNRS, UMR-8502 , Paris Sud, Orsay Cedex 91405, France.
authors.forename: Cristina
authors.initials: C
authors.lastname: Bena
authors.affiliation: Nanosciences group, CEMES CNRS-UPR 8011 , 29 Rue Jeanne Marvig, BP 94347, Toulouse 31055, France.
authors.forename: André
authors.initials: A
authors.lastname: Gourdon
authors.affiliation: Institut de Sciences des Matériaux de Mulhouse, CNRS-UMR 7361, Université de Haute Alsace , 3Bis, rue Alfred Werner, Mulhouse 68093, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Simon
keywords: Raman spectroscopy; UV and X-ray photoemission; covalent grafting; graphene functionalization; maleimide molecule; scanning tunneling microscopy