N-doped graphene can be used as a substrate for different molecules to effectively enhance their Raman scattering signal.

The electronic structure of nitrogen-containing diamondlike films prepared by sputtering was determined photoelectron spectroscopy. $\mathrm{N}1s$ core-level spectra are constituted two peaks at 400.5 and 398.2 eV associated with substitutional $\mathrm{N}{\mathrm{sp}}^{2}$ in aromatic rings N bonded to $\mathrm{C}{\mathrm{sp}}^{3},$ respectively. On increasing N, the top valence band suffers profound changes. new features identified a comparison experimental theoretically calculated density...

Efficient selection of semiconducting SWCNTs large diameter range (0.8-1.6 nm) on demand is demonstrated. Different diameters SWCNT are systematically selected by tuning the alkyl side-chain lengths wrapping polymers similar backbone. The exceptional quality and high concentration validated outstanding optical properties highly performing random network ambipolar field-effect transistors.

Large-area Si-doped graphene (SiG) is controllably synthesized for the first time. A much-enhanced molecular-sensing performance achieved when SiG used as a probing surface. This will open up opportunities developing high-performance sensors that are able to detect trace amounts of organic and fluorescent molecules. Furthermore, many fascinating properties predicted by theoretical calculations can be tested based on as-synthesized SiG.

We report on the photophysical properties of single-walled carbon nanotube (SWNT) suspensions in toluene solutions poly[9,9-dioctylfluorenyl-2,7-diyl](PFO). Steady-state and time-resolved photoluminescence spectroscopy near-infrared visible spectral regions are used to study interaction dispersed SWNTs with wrapped polymer. Molecular dynamics simulations PFO-SWNT hybrids were carried out evaluate energetics different wrapping geometries. The simulated fluorescence spectra region obtained by...

A series of randomly nitrogen-substituted carbon clusters in graphitelike structures, containing up to 96 atoms, is theoretically investigated through semiemipirical pseudopotential techniques. The evolution conformation and electronic structure obtained as a function nitrogen content. Results from semiempirical geometry optimizations reveal that the are planar for concentrations [N]/[C]\ensuremath{\sim}20%. Above this concentration, buckling develops clusters. One characteristics these...

The electronic structure of fully oxidized polyaniline, pernigraniline, is investigated in the framework Su-Schrieffer-Heeger Hamiltonian, making use an original renormalization technique. Among family polyanilines, pernigraniline only form to possess a degenerate ground state. It shown accomodate elementary excitations soliton and polaron types having remarkable properties, some instances markedly different from those predicted for so-called AB polymer. Nonlinear optical properties material...

We study a class of one-dimensional chains whose topology leads to flatbands in the electronic spectrum. Using Hubbard model, we find that these materials should exhibit ferrimagnetic ordering for half-filled band, agreement with theorem by Lieb. Away from half filling system displays very rich magnetic phase diagram. Possible experimental realizations are suggested.

The conformations and electronic structures of long oligoacenes [${\mathrm{C}}_{2}{\mathrm{H}}_{2}{({\mathrm{C}}_{4}{\mathrm{H}}_{2})}_{n}$, $20\ensuremath{\leqslant}n\ensuremath{\leqslant}23$] polyacene $[{({\mathrm{C}}_{8}{\mathrm{H}}_{4})}_{x}]$ were theoretically investigated through density functional theory adopting the hybrid B3LYP/6-31G(d) functional. present a cis conformation solitonlike distortions along chain. defective regions having uniform bond lengths produce localized states...

Carbon nanotubes with different nitrogen contents were produced by the arc-discharge technique. The samples first submitted to a concentration process (purification) and analyzed x-ray photoelectron spectroscopy, electron-energy-loss electron transmission, scanning microscopy study materials structure morphology. Measured values of below 5 at. % varied partial pressure inside chamber. Using an optical microscope, highly localized regions $(\ensuremath{\sim}1{\mathrm{mm}}^{2})$ irradiated Ar...

Several strategies aimed at sorting single-walled carbon nanotubes (SWNT) by diameter and/or electronic structure have been developed in recent years. A nondestructive method was recently proposed which nanotube bundles are dispersed water−surfactant solutions and submitted to ultracentrifugation a density gradient. By this method, SWNTs of different diameters distributed according their densities along the centrifuge tube. mixture two anionic amphiphiles, namely sodium dodecylsulfate (SDS)...

The isotopic effect on the infrared spectra is used to determine existence of nitrogen–hydrogen bonds in amorphous carbon–nitrogen alloys (a-CNx) prepared by dual-ion-beam-assisted deposition. deuteration experiments and evolution upon atmospheric exposure show that hydroxyls are incorporated from moisture.

Carbon nitride nanostructures have been produced by the arc-discharge technique and analyzed mass spectrometry. A series of structured peaks in region masses from 480 up to 600 suggests existence heterofullerenes C(n-x)Nx(40 < or = n 50). The structure stability these small fullerenes were theoretically investigated quantum chemical calculations. obtained heats formation indicate that C(n) molecules stabilize upon nitrogen substitution. Two C(n-x)Nx cages are quite stable, with per atom...

We present a theoretical study on the structural and electronic modifications caused by random nitrogen substitution in carbon tubular branched nanostructures. Finite cluster calculations with hydrogen saturation of tube ends were performed. Geometry optimizations carried out through semiempirical quantum chemical calculations. Densities states (DOS) calculated density functional theory. The energy associated incorporation was obtained. Some structures undergo length shortening as...

The origin of the vibrational modes $a\ensuremath{-}{\mathrm{CN}}_{x}$ alloys is investigated by infrared (ir) and Raman spectroscopies. Isotopic substitution ${}^{15}\mathrm{N}$ D used in identification vibration modes. In nonhydrogenated materials containing low nitrogen concentration (\ensuremath{\leqslant}20 at. %), ir spectra are not equivalent. Above this (up to \ensuremath{\sim}30 became very similar each other. On contrary, for a suitable hydrogen content quite similar, independently...

In this work we show that, beyond the prediction of random dimer model [Wu and Phillips, Phys. Rev. Lett. 66, 1366 (1991)], it is possible to have near resonant scattering from nonsymmetric dimers. It shown by direct density states calculations as well a procedure similar that protonated chains alkyl-substituted polyanilines support extended electronic at Fermi energy when disordered distribution symmetric or asymmetric bipolarons present. An extension include dimers proposed.

In the present work, electronic structure of polythiophene at several doping levels is investigated by use H\"uckel Hamiltonian with \ensuremath{\sigma}-bond compressibility. Excess charges are assumed to be stored in conformational defects bipolaron type. The matrix elements representative a obtained from previous thiophene oligomer calculation, and then transferred very long chains. Negative factor counting inverse iteration techniques have been used evaluate densities states wave...

Noble gases (Ar, Kr, and Xe) were trapped in an amorphous carbon matrix the 1--11-GPa pressure range. Extended near-edge x-ray-absorption spectroscopies indicate clustering of noble induced by host internal pressure. Simultaneously, promotes a shift noble-gas core-level binding energy $\ensuremath{\sim}1\mathrm{eV}.$ The Auger parameter reveals that both initial state relaxation terms contribute to binding-energy shift. Ab initio calculations performed on ${\mathrm{Ar}}_{7}$ cluster Ar atoms...

We employ photoluminescence and pump-probe spectroscopy on films of semiconducting single-walled carbon nanotubes (CNTs) different chirality wrapped with either a wide band gap polyfluorene derivative (PF12) or polythiophene narrower (P3DDT) to elucidate the excited states' interplay between two materials. Excitation above polymer gives way an ultrafast electron transfer from both polymers toward CNTs. By monitoring hole polaron via its mid infrared signature, we show that also illumination...

Abstract Noncovalent functionalization of single‐walled carbon nanotubes (SWNTs) using π‐conjugated polymers has become one the most effective techniques to select semiconducting SWNTs (s‐SWNTs). Several conjugated are used, but their ability sort metallic and species, as well dispersions yields, varies a function chemical structure. Here, three compared, namely, poly[2,6‐(4,4‐bis‐(2‐dodecyl)‐4H‐cyclopenta[2,1‐b;3,4b′]dithiophene)‐alt‐4,7(2,1,3‐benzothiadiazole)] (P12CPDTBT),...