title: Molecular Lifting, Twisting, and Curling during Metal-Assisted Polycyclic Hydrocarbon Dehydrogenation.
abstract: The atomistic understanding of the dissociation mechanisms for large molecules adsorbed on surfaces is still a challenge in heterogeneous catalysis. This is especially true for polycyclic aromatic hydrocarbons, which represent an important class of organic compounds used to produce novel graphene-based architectures. Here, we show that coronene molecules adsorbed on Ir(111) undergo major conformational changes during dissociation. They first tilt upward with respect to the surface, still keeping their planar configuration, and subsequently experience a rotation, which changes the molecular axis orientation. Upon lifting, the internal C-C strain is initially relieved; as the dehydrogenation proceeds, the molecules experience a progressive increase in the average interatomic distance and gradually settle to form dome-shaped nanographene flakes. Our results provide important insight into the complex mechanism of molecular breakup, which could have implications in the synthesis of new carbon-based nanostructured materials.
authors.affiliation: Physics Department, University of Trieste , Via Valerio 2, 34127 Trieste, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Curcio
authors.affiliation: Physics Department, University of Trieste , Via Valerio 2, 34127 Trieste, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Omiciuolo
authors.affiliation: Department of Earth Sciences, Department of Physics and Astronomy, Thomas Young Centre@UCL, London Centre for Nanotechnology, University College London , Gower Street, London WC1E 6BT, United Kingdom.
authors.forename: Monica
authors.initials: M
authors.lastname: Pozzo
authors.affiliation: Elettra-Sincrotrone Trieste S.C.p.A. , Strada Statale 14 km 163.5, 34149 Trieste, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Lacovig
authors.affiliation: Elettra-Sincrotrone Trieste S.C.p.A. , Strada Statale 14 km 163.5, 34149 Trieste, Italy.
authors.forename: Silvano
authors.initials: S
authors.lastname: Lizzit
authors.affiliation: Physics Department, University of Trieste , Via Valerio 2, 34127 Trieste, Italy.|International Centre for Theoretical Physics , Strada Costiera 11, 34151 Trieste, Italy.|Nanosciences & Catalysis Division, National Centre for Physics , Islamabad 44000, Pakistan.
authors.forename: Naila
authors.initials: N
authors.lastname: Jabeen
authors.affiliation: Elettra-Sincrotrone Trieste S.C.p.A. , Strada Statale 14 km 163.5, 34149 Trieste, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Petaccia
authors.affiliation: Department of Earth Sciences, Department of Physics and Astronomy, Thomas Young Centre@UCL, London Centre for Nanotechnology, University College London , Gower Street, London WC1E 6BT, United Kingdom.
authors.forename: Dario
authors.initials: D
authors.lastname: Alfè
authors.affiliation: Physics Department, University of Trieste , Via Valerio 2, 34127 Trieste, Italy.|Elettra-Sincrotrone Trieste S.C.p.A. , Strada Statale 14 km 163.5, 34149 Trieste, Italy.|Laboratorio TASC, IOM-CNR , AREA Science Park, Strada Statale 14 km 163.5, 34149 Trieste, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Baraldi