title: Energetics and hierarchical interactions of metal-phthalocyanines adsorbed on graphene/Ir(111).
abstract: The adsorption of metal-phthalocyanine (MPc) layers (M = Fe, Co, Cu) assembled on graphene/Ir(111) is studied by means of temperature-programmed X-ray photoemission spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS). The balance between interaction forces among the organometallic molecules and the underlying graphene gives rise to flat-lying molecular layers, weakly interacting with the underlying graphene. Further MPc layers pile up face-on onto the first layer, up to a few nanometers thickness, as deduced by NEXAFS. The FePc, CoPc, and CuPc multilayers present comparable desorption temperatures, compatible with molecule-molecule interactions dominated by van der Waals forces between the π-conjugated macrocycles. The MPc single layers desorb from graphene/Ir at higher temperatures. The CuPc single layer desorbs at lower temperature than the FePc and CoPc single layers, suggesting a higher adsorption energy of the FePc and CoPc single layers on graphene/Ir with respect to CuPc, with increasing molecule-substrate interaction in the order E(CuPc) < E(FePc) ~ E(CoPc).
authors.affiliation: Dipartimento di Fisica, CNISM, CNIS, Università di Roma La Sapienza, Piazzale Aldo Moro 2, 1-00185 Roma, Italy.
authors.forename: Mattia
authors.initials: M
authors.lastname: Scardamaglia
authors.forename: Claudia
authors.initials: C
authors.lastname: Struzzi
authors.forename: Silvano
authors.initials: S
authors.lastname: Lizzit
authors.forename: Matteo
authors.initials: M
authors.lastname: Dalmiglio
authors.forename: Paolo
authors.initials: P
authors.lastname: Lacovig
authors.forename: Alessandro
authors.initials: A
authors.lastname: Baraldi
authors.forename: Carlo
authors.initials: C
authors.lastname: Mariani
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Betti