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A newly developed adsorption process for a site- and orientation-selective anchoring of prototypical molecular building blocks on appropriate templates is described. The various data-sets obtained from the analysis shows that the specific adsorption angle observed is only due to the adsorption on the kink sites, as it requires the lowest energy.

[C.sub.60] nanostructures with long-range order and uniform size are prepared using a vicinal Au(11 12 12) surface, naturally patterned into a rectangular superlattice as a template. A two-dimensional long-range ordered superlattice of molecular nanochains is achieved at room temperature and at a coverage of 0.1 monolayer, which perfectly replicates the periodicity of the template surface.

The chiral molecule (R,R) -tartaric acid adsorbed on nickel surfaces creates highly enantioselective heterogeneous catalysts. At room temperature and low coverages, (R, R)-tartaric acid is adsorbed in its bitartrate form with two point bonding to the surface via both carboxylate groups and the molecule is preferentially located above the 4-fold hollow site with each carboxylate functionality adsorbed at the short bridge site via O atoms placed above adjacent Ni atoms.

The unusual structure of cobalt phthalocyanine on Cu(111) which is obtained from substrate-induced reduction of molecular symmetry and substrate-mediated interaction via quantum interference of surface electrons is reported. The interaction provides additional control over the symmetry of 2D crystals of phthalocyanindes and lead to a variety of other symmetries in self-assembled arrays.

Molecular layers are designed that have enabled bistable switching on a surface and have demonstrated control of a single switch in a dense and ordered array at the spatial limit. Up and down motion of a central Sn ion through the frame of a phthalocyanine molecule is obtained from the resonant electron or hole injection into molecular orbits.

A single-atom electronic switch in silicon due to molecularly induced field effects, is described. Small changes in configuration of a self-assembled pair of dipolar adsorbate molecules that surround a silicon atom are shown to possess a large electronic effect characterized by a high and a low conductance.

A larger aromatic pi-system is synthesized that shows extraordinarily high stability and an effective suppression of aggregation. Results reveal that the bulk properties in an extruded fiber as well as on the surface showed a columnar self-assembly including a phase in which homeotropic alignment on a substrate is observed.

By means of scanning tunneling microscopy and density functional theory calculations, we studied the water formation reaction on the Rh(110) surface when exposing the (2 × 1 )p2mg-O structure to molecular hydrogen, characterizing each of the structures that form on the surface during the reaction. First the reaction propagates on the surface as a wave front, removing half of the initial oxygen atoms. The remaining 0.5 monolayers of O atoms rearrange in pairs, forming a c(2 × 4) structure. Second, as the reaction proceeds, areas of an intermediate structure with c(2 × 2) symmetry appear and grow at the expense of the c(2 × 4) phase, involving all the oxygen atoms present on the surface. Afterward, the c(2 × 2) islands shrink, indicating that complete hydrogenation occurs at their edges, leaving behind a clean rhodium substrate. Two possible models for the c(2 × 2) structure, where not only the arrangement but also the chemical identity is different, are given. The first one is a mixed H + O structure, while the second one resembles the half-dissociated water layer already proposed on other metal surfaces. In both models, the high local oxygen coverage is achieved by the formation of a hexagonal network of hydrogen bonds. [ABSTRACT FROM AUTHOR]

Graphene on SiO 2 enables fabrication of Si-technology-compatible devices, but a transfer of these devices from other substrates and direct growth have severe limitations due to a relatively small grain size or device-contamination. Here, we show an efficient, transfer-free way to integrate centimeter-scale, single-crystal graphene, of a quality suitable for electronic devices, on an insulating SiO 2 film. Starting with single-crystal graphene grown epitaxially on Ru(0001), a SiO 2 film is grown under the graphene by stepwise intercalation of silicon and oxygen. Thin (∼1 nm) crystalline or thicker (∼2 nm) amorphous SiO 2 has been produced. The insulating nature of the thick amorphous SiO 2 is verified by transport measurements. The device-quality of the corresponding graphene was confirmed by the observation of Shubnikov-de Haas oscillations, an integer quantum Hall effect, and a weak antilocalization effect within in situ fabricated Hall bar devices. This work provides a reliable platform for applications of large-scale, high-quality graphene in electronics.

The quantum efficiency or the rate of conversion of incident photon to free electron in photosynthesis is known to be extremely high. It has long been thought that the origin of this efficiency are molecular vibrations leading to a very fast separation of electrons and holes within the involved molecules. However, molecular vibrations are commonly in the range above 100 meV, which is too high for excitations in an ambient environment. Here, we analyze experimental spectra of single organic molecules on metal surfaces at ∼4 K, which often exhibit a pronounced dip. We show that measurements on iron(II) [tetra-(pentafluorophenyl)]porphyrin resolve this single dip at 4 K into a series of step-shaped inelastic excitations at 0.4 K. Via extensive spectral maps under applied magnetic fields and corresponding theoretical analysis we find that the dip is due to ultralow-energy vibrations of the molecular frame, typically in the range below 20 meV. The result indicates that ultralow energy vibrations in organic molecules are much more common than currently thought and may be all-pervasive for molecules above a certain size.

A key requirement for the future applicability of molecular electronics devices is a resilience of their properties to mechanical deformation. At present, however, there is no fundamental understanding of the origins of mechanical properties of molecular films. Here we use quinacridone, which possesses flexible carbon side chains, as a model molecular system to address this issue. Eight molecular configurations with different molecular coverage are identified by scanning tunneling microscopy. Theoretical calculations reveal quantitatively the roles of different molecule-molecule and molecule-substrate interactions and predict the observed sequence of configurations. Remarkably, we find that a single Young's modulus applies for all configurations, the magnitude of which is controlled by side chain length, suggesting a versatile avenue for tuning not only the physical and chemical properties of molecular films but also their elastic properties., (© 2012 American Chemical Society)

If a molecule controls the length of some other moiety, it can be termed a "molecular caliper". Here we image individual molecular calipers of this type by scanning tunneling microscopy. These consist of linear polymers of p-diiodobenzene, (pDIB)n, of varying length, 0.7-2.9 nm, physisorbed on Cu(110) at 4.6 K. Through electron-induced reaction these chemically imprint their terminal I-atoms on the copper, 0.7 nm further apart than their initial separations. The physisorbed monomer or polymer, therefore, constitutes a molecular-caliper with variable terminal I..I separation. The localized nature of the I-atom reaction at the copper surface relative to the parent molecule, constitutes a novel finding reported here. It ensures that the separation of the I-atoms in the physisorbed molecular caliper correlates with their subsequent separation when chemisorbed at the surface.