One Precursor but Two Types of Graphene Nanoribbons: On-Surface Transformations of 10,10’-dichloro-9,9’-bianthryl on Ag(111)

On-surface synthesis has emerged in the last decade as a method to create graphene nanoribbons (GNRs) with atomic precision. The underlying premise of this bottom-up strategy is that precursor molecules undergo a well-defined sequence of inter- and intramolecular reactions, leading to the formation of a single product. As such, the structure of the GNR is encoded in the precursors. However, recent examples have shown that not only the molecule, but also the coinage metal surface on which the reaction takes place, plays a decisive role in dictating the nanoribbon structure. In this work, we use scanning probe microscopy (SPM) and x-ray photoelectron spectroscopy (XPS) to investigate the behavior of 10,10’-dichloro-9,9’-bianthryl (DCBA) on Ag(111). Our study shows that Ag(111) can induce the formation of both 7-atom wide armchair graphene nanoribbons (7-acGNRs) and 3,1-chiral graphene nanoribbons (3,1-cGNRs), demonstrating that a single molecule on a single surface can react to different nanoribbon products. We additionally show that coadsorbed dibromoperylene (DBP) can promote surface-assisted dehydrogenative coupling in DCBA, leading to the exclusive formation of 3,1-cGNRs

One Precursor but Two Types of Graphene Nanoribbons: On-Surface Transformations of 10,10’-dichloro-9,9’-bianthryl on Ag(111)

On-surface synthesis has emerged in the last decade as a method to create graphene nanoribbons (GNRs) with atomic precision. The underlying premise of this bottom-up strategy is that precursor molecules undergo a well-defined sequence of inter- and intramolecular reactions, leading to the formation of a single product. As such, the structure of the GNR is encoded in the precursors. However, recent examples have shown that not only the molecule, but also the coinage metal surface on which the reaction takes place, plays a decisive role in dictating the nanoribbon structure. In this work, we use scanning probe microscopy (SPM) and x-ray photoelectron spectroscopy (XPS) to investigate the behavior of 10,10’-dichloro-9,9’-bianthryl (DCBA) on Ag(111). Our study shows that Ag(111) can induce the formation of both 7-atom wide armchair graphene nanoribbons (7-acGNRs) and 3,1-chiral graphene nanoribbons (3,1-cGNRs), demonstrating that a single molecule on a single surface can react to different nanoribbon products. We additionally show that coadsorbed dibromoperylene (DBP) can promote surface-assisted dehydrogenative coupling in DCBA, leading to the exclusive formation of 3,1-cGNRs

First measurement of the helicity dependence of He-3 photoreactions in the Delta(1232) resonance region

The first measurement of the helicity dependence of the total inclusive He-3 photo-absorption cross section and of the partial cross sections for several reaction channels was carried out at MAMI (Mainz) in the photon energy range between 150 and 500 MeV. The experiment used the large acceptance Crystal Ball spectrometer, complemented by charged particle and vertex detectors, a circularly polarised tagged photon beam and a longitudinally polarised high-pressure He-3 gas target. The results obtained give information on the GDH integral on He-3 and on the neutron and allow an investigation of the modifications of nucleon properties inside He-3. (c) 2013 Published by Elsevier B.V