Graphite vaporization provides an uncontrolled yet efficient means of producing fullerene molecules. However, some fullerene derivatives or unusual fullerene species might only be accessible through rational and controlled synthesis methods. Recently, such an approach has been used to produce isolable amounts of the fullerene C(60) from commercially available starting materials. But the overall process required 11 steps to generate a suitable polycyclic aromatic precursor molecule, which was then dehydrogenated in the gas phase with a yield of only about one per cent. Here we report the formation of C(60) and the triazafullerene C(57)N(3) from aromatic precursors using a highly efficient surface-catalysed cyclodehydrogenation process. We find that after deposition onto a platinum (111) surface and heating to 750 K, the precursors are transformed into the corresponding fullerene and triazafullerene molecules with about 100 per cent yield. We expect that this approach will allow the production of a range of other fullerenes and heterofullerenes, once suitable precursors are available. Also, if the process is carried out in an atmosphere containing guest species, it might even allow the encapsulation of atoms or small molecules to form endohedral fullerenes.

STM images of multidomain epitaxial graphene on Pt(111) have been combined with a geometrical model to investigate the origin of the coincidence Moiré superstructures. We show that there is a relation between the appearance of a particular Moiré periodicity and the minimization of the absolute value of the strain between the graphene and the substrate for the different orientations between both atomic lattices. This model predicts all the stable epitaxial graphene structures that can be grown on transition metal surfaces, and we have made use of it for reproducing previously published data from different authors. Its validity suggests that minimization of the strain within the coincident graphene unit-cell due to a strong local interaction is the driving force in the formation of Moiré superstructures.

The properties of water at the nanoscale are crucial in many areas of biology, but the confinement of water molecules in sub-nanometre channels in biological systems has received relatively little attention. Advances in nanotechnology make it possible to explore the role played by water molecules in living systems, potentially leading to the development of ultrasensitive biosensors. Here we show that the adsorption of water by a self-assembled monolayer of single-stranded DNA on a silicon microcantilever can be detected by measuring how the tension in the monolayer changes as a result of hydration. Our approach relies on the microcantilever bending by an amount that depends on the tension in the monolayer. In particular, we find that the tension changes dramatically when the monolayer interacts with either complementary or single mismatched single-stranded DNA targets. Our results suggest that the tension is mainly governed by hydration forces in the channels between the DNA molecules and could lead to the development of a label-free DNA biosensor that can detect single mutations. The technique provides sensitivity in the femtomolar range that is at least two orders of magnitude better than that obtained previously with label-free nanomechanical biosensors and with label-dependent microarrays.

The electroadsorption of S on Au(111) from 0.1 M NaOH + 3 × 10 -3 M Na2S solutions has been studied by in situ scanning tunneling microscopy (STM), electrochemical methods, and ex situ X-ray photoemission spectrocopy (XPS). By analyzing STM images, we have observed that S adsorbs on Au(111) forming a 3× 3R30°superstructure. Under potential control this lattice slowly and continuously transforms into S octomers (S8) in the range -0.7/-0.5 V (i.e., at typical potentials observed under open circuit conditions). In this potential range, mixtures of both structures are present on the Au(111) surface. An XPS study of the S 2p peak from the adlayers reveals the presence of three components that can be assigned to S forming a 3× 3R30°structure, S8, and bulk S at surface defects. The most important component is that corresponding to S8, in good agreement with the STM images. Furthermore, XPS spectra recorded for 3× 3R30°thiol adlayers on Au(111), characterized by STM and atomic force microscopy, lead to similar S 2p XPS spectra. A comparison between these cases allows us to conclude that S in spontaneously formed S8 on Au(111) exhibits the same binding energy of the core electronic levels (i.e., same chemical state) as S in 3× 3R30°spontaneously formed thiol lattices, although the adsorption sites are different.

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We report hot filament thermal CVD (HFTCVD) as a new hybrid of hot filament and thermal CVD and demonstrate its feasibility by producing high quality large area strictly monolayer graphene films on Cu substrates. Gradient in gas composition and flow rate that arises due to smart placement of the substrate inside the Ta filament wound alumina tube accompanied by radical formation on Ta due to precracking coupled with substrate mediated physicochemical processes like diffusion, polymerization etc., led to graphene growth. We further confirmed our mechanistic hypothesis by depositing graphene on Ni and SiO2/Si substrates. HFTCVD can be further extended to dope graphene with various heteroatoms (H, N, and B, etc.,), combine with functional materials (diamond, carbon nanotubes etc.,) and can be extended to all other materials (Si, SiO2, SiC etc.,) and processes (initiator polymerization, TFT processing) possible by HFCVD and thermal CVD.