Fabrication of three terminal devices by ElectroSpray deposition of graphene nanoribbons

Electrospray deposition (ESD) in ambient conditions has been used to deposit graphene nanoribbons (GNRs) dispersed in liquid phase on different types of substrates, including ones suitable for electrical transport. The deposition process was controlled and optimized by using Raman spectroscopy, Scanning Probe Microscopies and Scanning Electron Microscopy. When deposited on graphitic electrodes, GNRs were used as semi-conducting channel in three terminal devices showing gate tunability of the electrical current. These results suggest that ESD technique can be used as an effective tool to deposit chemically synthesized GNRs onto substrates of interest for technological applications

SHAPE PERSISTENCE AND TRAPPING IN POLYPHENYLENE DENDRIMERS: NEW CARBON BASED SENSOR MATERIALS?

The interest on diffusion and trapping of small molecules inside dendrimers has increased in recent years because of the new synthetic strategies that have allowed to achieve a high control of the supramolecular structure of these macromolecules. Crucial, in this regard, are the dimension and topology of intra- and inter-molecular cavities that can capture small molecules, along with the nature (physical or chemical) of the penetrant/dendrimer interaction. In recent years a divergent method to synthesize polyphenylene dendrimers with different cores and up to the fourth generation has been developed [1]. Owing to their semi-rigid framework, these monodisperse polyaromatic dendrimers are of interest with respect to the design of nanostructures with invariant shape [2] and because of their cavities they are promising materials for selective sensor layers [3]. In this work we present a computational study on both intra-molecular and inter-molecular properties of polyphenylene dendrimers with a three-substituted phenyl core. The first objective is to assess the degree of intra-molecular shape persistence at different temperatures. To this end atomistic molecular dynamics simulations have been carried out at 80 K and room temperature. It is found that out of the six possible core conformations only four are stable and jumps among these are possible at room temperature, although core conformational jumps induce only slight shape modifications of the polyphenylene dendrimer. The second objective of this study is to explore whether aggregates of these peculiar three-dimensional structures can form stable inter- and intra-molecular cavities and to investigate their trapping capacity. To this end, accessible surfaces and trapping sites have been studied by employing an in-house written algorithm in which the preferential approaching paths for external molecules moving toward intra- or inter-dendrimer cavities (trapping sites) are evaluated on the basis of a selected grid of points used by the penetrant to explore the accessible volume and with a Monte Carlo sampling. [1] A. J. Berresheim, M.M\ufcller, K. M\ufcllen, Chem. Rev., 99 (1999), 1747. [2] F. Morgenroth, A. J. Berresheim, M.Wagner, K. M\ufcllen, Chem. Commun., 10 (1998), 1139. [3] M. Schlupp, T. Weil, A. J. Berresheim, U. M. Wiesler, J. Bargon, K. M\ufcllen, Angew. Chem. Int. Ed. 40 (2001), 4011

SHAPE PERSISTENCE AND TRAPPING IN POLYPHENYLENE DENDRIMERS: NEW CARBON BASED SENSOR MATERIALS?

The interest on diffusion and trapping of small molecules inside dendrimers has increased in recent years because of the new synthetic strategies that have allowed to achieve a high control of the supramolecular structure of these macromolecules. Crucial, in this regard, are the dimension and topology of intra- and inter-molecular cavities that can capture small molecules, along with the nature (physical or chemical) of the penetrant/dendrimer interaction. In recent years a divergent method to synthesize polyphenylene dendrimers with different cores and up to the fourth generation has been developed [1]. Owing to their semi-rigid framework, these monodisperse polyaromatic dendrimers are of interest with respect to the design of nanostructures with invariant shape [2] and because of their cavities they are promising materials for selective sensor layers [3]. In this work we present a computational study on both intra-molecular and inter-molecular properties of polyphenylene dendrimers with a three-substituted phenyl core. The first objective is to assess the degree of intra-molecular shape persistence at different temperatures. To this end atomistic molecular dynamics simulations have been carried out at 80 K and room temperature. It is found that out of the six possible core conformations only four are stable and jumps among these are possible at room temperature, although core conformational jumps induce only slight shape modifications of the polyphenylene dendrimer. The second objective of this study is to explore whether aggregates of these peculiar three-dimensional structures can form stable inter- and intra-molecular cavities and to investigate their trapping capacity. To this end, accessible surfaces and trapping sites have been studied by employing an in-house written algorithm in which the preferential approaching paths for external molecules moving toward intra- or inter-dendrimer cavities (trapping sites) are evaluated on the basis of a selected grid of points used by the penetrant to explore the accessible volume and with a Monte Carlo sampling. [1] A. J. Berresheim, M.M\ufcller, K. M\ufcllen, Chem. Rev., 99 (1999), 1747. [2] F. Morgenroth, A. J. Berresheim, M.Wagner, K. M\ufcllen, Chem. Commun., 10 (1998), 1139. [3] M. Schlupp, T. Weil, A. J. Berresheim, U. M. Wiesler, J. Bargon, K. M\ufcllen, Angew. Chem. Int. Ed. 40 (2001), 4011

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PARIS5-BU Saints-Pères (751062109) / SudocSudocFranceF

Electron dynamics in unoccupied states of spatially aligned 7-a graphene nanoribbons on Au(788)

Bottom-up synthesized armchair graphene nanoribbons with a width of seven C\u2009=\u2009C bonds (7-aGNRs) have gained widespread interest due to their large band gap of about 2.8 eV and their atomically precise edge structures. Here, we report on the lifetime of excited states of spatially aligned 7-aGNRs grown on a vicinal Au(788) surface. Time-resolved three-photon photoemission spectroscopy at h\u3bd=3.15 eV was carried out to measure the lifetimes of states located at E1 12EF=3.6 eV and E2 12EF=3.8 eV via a resonant excitation from an unoccupied state at E 12EF=0.6 eV. Lifetimes of \u3c41=(110\ub113) fs and \u3c42=(75\ub110) fs are observed, respectively