Contributing to the need for new graphene nanoribbon (GNR) structures that can be synthesized with atomic precision, we have designed a reactant that renders chiral (3,1)-GNRs after a multistep reaction including Ullmann coupling and cyclodehydrogenation. The nanoribbon synthesis has been successfully proven on different coinage metals, and the formation process, together with the fingerprints associated with each reaction step, has been studied by combining scanning tunneling microscopy, core-level spectroscopy, and density functional calculations. In addition to the GNR’s chiral edge structure, the substantial GNR lengths achieved and the low processing temperature required to complete the reaction grant this reactant extremely interesting properties for potential applications.

Quantum well states are found at the Fermi level in Cu on Co(100) and Ag on Fe(100) using inverse photoemission. They appear every 5.9 ±0.5 layers in Cu/CoGOO), which agrees with the 5.5-to 6-layer oscillation period of the magnetic coupling in Cu/Co(100) superlattices. For Ag/Fe(l00) they connect with minority-spin interface states observed below £> previously, providing a magnetic coupling channel through the noble metal. These properties are explained in terms of the bulk band structure.PACS numbers: 75.50. Rr, 73.20.Dx, 75.70.Cn, 79.20.Kz The electronic structure of metallic superlattices is gaining interest for designing new solids with flexible properties. Recently, an oscillatory magnetic coupling observed in magnetic superlattices [1-9] has created widespread interest, due both to the potential applications in magnetic and magneto-optic storage, and to the unusual oscillation period. The latter is on the order of 10 A, which is much larger than the Fermi wavelength expected from simple arguments. A variety of theoretical models [10][11][12][13][14] have been proposed to explain this behavior. Our aim is to find the electronic states that mediate the magnetic coupling. We are particularly interested in noble metal spacer layers, because it is not obvious how a noble metal can transmit the magnetic interaction over distances of many atomic layers. In order to narrow the field we notice that states near the Fermi level £> are expected to contribute the most to magnetic phenomena. After all, the changes in the density of states within kT c (Tc =Curie temperature) of £> drive the magnetic phase transition. In momentum space, we will therefore have to consider the whole Fermi surface, but the direction perpendicular to the interfaces of the superlattice will be emphasized by symmetry.

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Vicinal noble metal surfaces with regular arrays of steps and terraces are very convenient model systems to test the electronic properties of lateral nanostructures. Using angle-resolved photoemission with synchrotron radiation we thoroughly characterize electronic states and wavefunctions in a variety of vicinal Cu(111) and Au(111) surfaces. By tuning the terrace width, we can observe the fundamental transition from arrays of non-interacting nano-objects (terraces), where electron states are confined, to lateral coupling between terraces, which leads to superlattice states.

The molecule/metal interface is the key element in charge injection devices. It can be generally defined by a monolayer-thick blend of donor and/or acceptor molecules in contact with a metal surface. Energy barriers for electron and hole injection are determined by the offset from HOMO (highest occupied) and LUMO (lowest unoccupied) molecular levels of this contact layer with respect to the Fermi level of the metal electrode. However, the HOMO and LUMO alignment is not easy to elucidate in complex multicomponent, molecule/metal systems. We demonstrate that core-level photoemission from donor-acceptor/metal interfaces can be used to straightforwardly and transparently assess molecular-level alignment. Systematic experiments in a variety of systems show characteristic binding energy shifts in core levels as a function of molecular donor/acceptor ratio, irrespective of the molecule or the metal. Such shifts reveal how the level alignment at the molecule/metal interface varies as a function of the donor-acceptor stoichiometry in the contact blend.

Metal–organic interfaces based on copper-phthalocyanine monolayers are studied in dependence of the metal substrate (Au versus Cu), of its symmetry [hexagonal (111) surfaces versus fourfold (100) surfaces], as well as of the donor or acceptor semiconducting character associated with the nonfluorinated or perfluorinated molecules, respectively. Comparison of the properties of these systematically varied metal–organic interfaces provides new insight into the effect of each of the previously mentioned parameters on the molecule–substrate interactions.

Increasingly high hopes are being placed on organic semiconductors for a variety of applications. Progress along these lines, however, requires the design and growth of increasingly complex systems with well-defined structural and electronic properties. These issues have been studied and reviewed extensively in single-component layers, but the focus is gradually shifting towards more complex and functional multi-component assemblies such as donor-acceptor networks. These blends show different properties from those of the corresponding single-component layers, and the understanding on how these properties depend on the different supramolecular environment of multi-component assemblies is crucial for the advancement of organic devices. Here, our understanding of two-dimensional multi-component layers on solid substrates is reviewed. Regarding the structure, the driving forces behind the self-assembly of these systems are described. Regarding the electronic properties, recent insights into how these are affected as the molecule's supramolecular environment changes are explained. Key information for the design and controlled growth of complex, functional multicomponent structures by self-assembly is summarized.

Quantum dots are known to confine electrons within their structure. Whenever they periodically aggregate into arrays and cooperative interactions arise, novel quantum properties suitable for technological applications show up. Control over the potential barriers existing between neighboring quantum dots is therefore essential to alter their mutual crosstalk. Here we show that precise engineering of the barrier width can be experimentally achieved on surfaces by a single atom substitution in a haloaromatic compound, which in turn tunes the confinement properties through the degree of quantum dot intercoupling. We achieved this by generating self-assembled molecular nanoporous networks that confine the two-dimensional electron gas present at the surface. Indeed, these extended arrays form up on bulk surface and thin silver films alike, maintaining their overall interdot coupling. These findings pave the way to reach full control over two-dimensional electron gases by means of self-assembled molecular networks.