title: From Graphene Nanoribbons on Cu(111) to Nanographene on Cu(110): Critical Role of Substrate Structure in the Bottom-Up Fabrication Strategy.
abstract: Bottom-up strategies can be effectively implemented for the fabrication of atomically precise graphene nanoribbons. Recently, using 10,10'-dibromo-9,9'-bianthracene (DBBA) as a molecular precursor to grow armchair nanoribbons on Au(111) and Cu(111), we have shown that substrate activity considerably affects the dynamics of ribbon formation, nonetheless without significant modifications in the growth mechanism. In this paper we compare the on-surface reaction pathways for DBBA molecules on Cu(111) and Cu(110). Evolution of both systems has been studied via a combination of core-level X-ray spectroscopies, scanning tunneling microscopy, and theoretical calculations. Experimental and theoretical results reveal a significant increase in reactivity for the open and anisotropic Cu(110) surface in comparison with the close-packed Cu(111). This increased reactivity results in a predominance of the molecular-substrate interaction over the intermolecular one, which has a critical impact on the transformations of DBBA on Cu(110). Unlike DBBA on Cu(111), the Ullmann coupling cannot be realized for DBBA/Cu(110) and the growth of nanoribbons via this mechanism is blocked. Instead, annealing of DBBA on Cu(110) at 250 °C results in the formation of a new structure: quasi-zero-dimensional flat nanographenes. Each nanographene unit has dehydrogenated zigzag edges bonded to the underlying Cu rows and oriented with the hydrogen-terminated armchair edge parallel to the [1-10] direction. Strong bonding of nanographene to the substrate manifests itself in a high adsorption energy of -12.7 eV and significant charge transfer of 3.46e from the copper surface. Nanographene units coordinated with bromine adatoms are able to arrange in highly regular arrays potentially suitable for nanotemplating.
authors: Department of Physics and Astronomy, Uppsala University , Box 516, 75120 Uppsala, Sweden.|MAX IV Laboratory, Lund University , Box 118, 22100 Lund, Sweden.|V.A. Fock Institute of Physics, St. Petersburg State University , 198504 St. Petersburg, Russia.
authors: Konstantin A
authors: KA
authors: Simonov
authors: Department of Physics and Astronomy, Uppsala University , Box 516, 75120 Uppsala, Sweden.|MAX IV Laboratory, Lund University , Box 118, 22100 Lund, Sweden.|V.A. Fock Institute of Physics, St. Petersburg State University , 198504 St. Petersburg, Russia.
authors: Nikolay A
authors: NA
authors: Vinogradov
authors: V.A. Fock Institute of Physics, St. Petersburg State University , 198504 St. Petersburg, Russia.
authors: Alexander S
authors: AS
authors: Vinogradov
authors: MAX IV Laboratory, Lund University , Box 118, 22100 Lund, Sweden.|V.A. Fock Institute of Physics, St. Petersburg State University , 198504 St. Petersburg, Russia.
authors: Alexander V
authors: AV
authors: Generalov
authors: V.A. Fock Institute of Physics, St. Petersburg State University , 198504 St. Petersburg, Russia.
authors: Elena M
authors: EM
authors: Zagrebina
authors: V.A. Fock Institute of Physics, St. Petersburg State University , 198504 St. Petersburg, Russia.
authors: Gleb I
authors: GI
authors: Svirskiy
authors: School of Physical Sciences, Dublin City University , Dublin 9, Ireland.
authors: Attilio A
authors: AA
authors: Cafolla
authors: School of Physical Sciences, Dublin City University , Dublin 9, Ireland.
authors: Thomas
authors: T
authors: Carpy
authors: School of Physical Sciences, Dublin City University , Dublin 9, Ireland.
authors: John P
authors: JP
authors: Cunniffe
authors: Department of Chemistry, Faculty of Science, Hokkaido University , Sapporo 060-0810, Japan.|Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS) , Tsukuba 305-0044, Japan.
authors: Tetsuya
authors: T
authors: Taketsugu
authors: Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS) , Tsukuba 305-0044, Japan.
authors: Andrey
authors: A
authors: Lyalin
authors: Department of Physics and Astronomy, Uppsala University , Box 516, 75120 Uppsala, Sweden.
authors: Nils
authors: N
authors: Mårtensson
authors: MAX IV Laboratory, Lund University , Box 118, 22100 Lund, Sweden.
authors: Alexei B
authors: AB
authors: Preobrajenski
keywords: DFT; STM; Ullmann reaction; X-ray absorption; graphene nanoribbons; nanographene; photoemission