Band gap opening and engineering is one of the high priority goals in the development of graphene electronics. Here, we report on the opening and scaling of band gap in BN doped graphene (BNG) films grown by low-pressure chemical vapor deposition method. High resolution transmission electron microscopy is employed to resolve the graphene and h-BN domain formation in great detail. X-ray photoelectron, micro-Raman, and UV-vis spectroscopy studies revealed a distinct structural and phase evolution in BNG films at low BN concentration. Synchrotron radiation based XAS-XES measurements concluded a gap opening in BNG films, which is also confirmed by field effect transistor measurements. For the first time, a significant band gap as high as 600 meV is observed for low BN concentrations and is attributed to the opening of the π-π* band gap of graphene due to isoelectronic BN doping. As-grown films exhibit structural evolution from homogeneously dispersed small BN clusters to large sized BN domains with embedded diminutive graphene domains. The evolution is described in terms of competitive growth among h-BN and graphene domains with increasing BN concentration. The present results pave way for the development of band gap engineered BN doped graphene-based devices.

Self-assembled monolayers (SAMs) formed from [1,1‘-biphenyl]-4,4‘-dimethanethiol (BPDMT) and [1,1‘;4‘,1‘ ‘-terphenyl]-4,4‘ ‘-dimethanethiol (TPDMT) on Au were characterized by X-ray photoelectron spectroscopy (XPS), high-resolution XPS, infrared reflection absorption spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and water contact angle measurements. The results of all experimental techniques suggest the formation of densely packed and highly oriented SAMs for both BPDMT and TPDMT, with a slightly higher packing density and a smaller molecular inclination in TPDMT/Au. All molecules were found to be bound to the substrate via the thiolate link, i.e., by one of the thiol groups, whereas the second thiol group is located at the SAM−ambient interface. This suggests that aromatic dithiols are well-suited for the fabrication of thiol-terminated SAMs. Such films are of particular importance for molecular electronics, since the thiol group has a high affinity to metals and can be used as a chemical link between a metal nanowire and the molecule.

Radiation damage of self-assembled monolayers, which are prototypes of thin organic layers and highly organized biological systems, shows a strong dependence on temperature. Two limiting cases could be identified. Reactions involving transport of single atoms and small fragments proceed nearly independent of temperature. Reactions requiring transport of heavy fragments are, however, efficiently quenched by cooling. We foresee the combined use of temperature and irradiation by electrons or photons for advanced tailoring of self-assembled monolayers on surfaces. In addition, our results have direct implications for cryogenic approaches in advanced electron and x-ray microscopy and spectroscopy of biological macromolecules and cells.

strongly connected grains and without AEC phases by a simple electrophoretic deposition technique. It is therefore thought that the present results may provide a significant breakthrough for the high-T c superconducting film and wire fabrication industries. ExperimentalPristine Bi 2 Sr 2 CaCu 2 O 8+y (Bi2212) was prepared by a conventional solid-state reaction [10±14]. As a secondary precursor, HgI 2 intercalates were synthesized through hard±soft acid±base reactions, as documented in our previous reports [10±14]. To intercalate (PyC 12 H 25 ) 2 -HgI 4 (where Py = pyridine), the HgI 2 -intercalates were mixed with a three-times molar excess of Py-C 12 H 25 I, and then a few drops of analytical grade (³ 99.8 % purity) acetone were added to the mixture. Each of the resulting mixtures was reacted in a closed ampoule at 50±60 C for 48 h. Finally, the dark-brown gel-like products were washed with acetone to remove the excess organic salts on the crystal surfaces. Exfoliation of the bisalkylpyridinium tetraiodomercurate [(Py-C 12 H 25 ) 2 HgI 4 ] intercalates was carried out by sonicating them at 28 kHz in acetone solvent, which was kept in an ice bath to prevent overheating of the suspension. For the fabrication of superconducting films and microwires, the exfoliated Bi2212 nanosheets in acetone solvent were electrophoretically deposited onto Ag substrates with a power-source meter (Keithley 2400) using a Pt plate (2 cm 5 cm) as a counter-electrode. As-deposited films and wires were subsequently heated at 840 C for 12 h.