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Using laser-induced vaporisation to evaporate and ionise a source of curved polyaromatic hydrocarbons (carbon nanobelts), we show collision impacts between species cause mass loss and the resultant ions are catalogued via mass-spectrometry. These data are interpreted via a series of “in-silico”-simulated systematic hydrogen-loss studies using density functional theory modelling, sequentially removing hydrogen atoms using thermodynamic stability as a selection for subsequent dehydrogenation. Initial hydrogen loss results in the formation of carbyne chains and pentagon-chains while the nanobelt rings are maintained, giving rise to new circular strained dehydrobenzoannulene species. The chains subsequently break, releasing CH and C2. Alternative routes towards the formation of closed-cages (fullerenes) are identified but shown to be less stable than chain formation, and are not observed experimentally. The results provide important information on collision degradation routes of curved molecular carbon species, and notably serve as a useful guide to high-energy impact conditions observed in some astrochemical environments.

The transition between gapped (semiconducting) and gapless (metallic) phases and tunability of bandgap in materials is a very lucrative yet considerably challenging goal for new-age device preparation. For bulk materials and for two-dimensional layered systems, this is a rapidly expanding field. We theoretically propose a one-dimensional pure carbon material with a tunable bandgap. We find that two parallel coupled polyyne chains show metallic behaviour with bands crossing on the Fermi level, unlike the single semiconducting chain. The number of nodal points (two) is robust under transverse and longitudinal strain, indicating the symmetry-protected nature of the metallic phase. Sliding one chain with respect to the other breaks reflection symmetry and a clear bandgap opens up at the nodes, leading to a gapped phase. By varying the slide parameter, the bandgap can be tuned efficiently. This work initiates and indicates possible topological phases of real one-dimensional materials without the involvement of edge modes., Comment: Accepted in Carbon Trends for publication

In the present work we develop a Monte Carlo algorithm of the carbon chains ordered into 2D hexagonal array. The chemical bond of the chained carbon is computed from 1 K to 1300 K. Our model confirms that the beta phase is more energetic preferable at low temperatures but the system prefers to switch into alpha phase at high temperatures. Based on the thermal effect on the bond distributions of the carbon chains, the bond softening temperature is observed at 500 K. The bond softening temperature is higher in the presence of interstitial doping but it does not change with the length of nanowire. The elastic modulus of the carbon chains is 1.7 TPa at 5 K and the thermal expansion is +7 × 10−5 K−1 at 300 K via monitoring the collective atomic vibrations and bond distributions. Thermal fluctuation in terms of heat capacity as a function of temperatures is computed in order to study the phase transition across melting point. The heat capacity anomaly initiates around 3800 K. © 2016 Elsevier Ltd

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We studied monoatomic linear carbon chains stabilised by gold nanoparticles attached to their ends and deposited on a solid substrate. We observe spectral features of straight chains containing from 8 to 24 atoms. Low temperature PL spectra reveal characteristic triplet fine-structures that repeat themselves for carbon chains of different lengths. The triplet is invariably composed of a sharp intense peak accompanied by two broader satellites situated 15 and 40 meV below the main peak. We interpret these resonances as an edge-state neutral exciton, positively and negatively charged trions, respectively. The time-resolved PL shows that the radiative lifetime of the observed quasiparticles is about 1 ns, and it increases with the increase of the length of the chain. At high temperatures a non-radiative exciton decay channel appears due to the thermal hopping of carriers between parallel carbon chains. Excitons in carbon chains possess large oscillator strengths and extremely low inhomogeneous broadenings., Comment: 23 pages, 5 figures

We describe the synthesis, characterization and use of a composite material made of a renewable source and metallic nanoparticles for biosensing applications. Nanocrystalline cellulose (NCC) is a product isolated from natural cellulose fibers, which is of approximately 100 nm long and 10 nm wide in size. We augmented the surface area and tailored the chemical affinity of NCC by optimally dressing it with gold nanoparticles (AuNPs). The deposition of AuNPs on NCC was controlled by using cationic polyethylenimine (PEI) at different pHs. AuNPs were thiol-functionalized using different linkers prior to enzyme immobilization. The enzyme (glucose oxidase or GOx) was conjugated on the composite by carbodiimide coupling, and subsequent activation of linker-carboxylic acid group. Our results showed that GOx was attached to the surface of the NCC nanocomposite. Moreover, the amount of GOx loaded onto the support depended on the length of the thiol-linker used. The lower value (20. 3 mg/mg of support) was obtained with the longer thiol-linker (11 carbon chain) compared to 25. 2 mg/mg of support for the smaller thiol-linker (3 carbon chain). © 2012 Springer Science+Business Media Dordrecht.

Combustion behavior of various oxygenated fuels has been studied in a DAF heavy-duty (HD) direct-injection (DI) diesel engine. From these fuels, it is well-known that they lead to lower particle (PM) emissions; however, for a given fuel oxygen mass fraction, there are significant differences in PM reduction. Although this can be traced back to the specific molecular structure of the oxygenate in question, no consensus can be found in the literature as to the explanation hereof. In this study, the sooting tendency (smoke number) of three oxygenates [viz., tripropylene glycol methyl ether (TP), dibutyl maleate (DB), and cyclohexanone (X1)] was compared to that of commercial diesel fuel (EN590, D). The results suggest that the cetane number (CN) (i.e., fuel reactivity) may play an important role. More specifically, the low reactive oxygenate X1, with its cyclic carbon chain, was found to perform exceptionally well compared to the more reactive linear and branched oxygenates DB and TP, respectively. Cyclic oxygenates are abundant in nature. Cellulose, the most common organic compound on earth, is the best-known example. Although it is not trivial, liquid cyclic oxygenates can be made from lignocellulosic biomass. Particularly, the production of C6 oxygenates (e.g., guaiacol, cyclohexanone, phenol, etc.), which can be derived from lignin, is the subject of current investigation. Fuels produced from such biomass (e.g., plant waste or the nonedible part of plants) are referred to as second-generation biofuels and are expected to play a pivotal role in the near future.

Brazil has played an important role in the development and use of resonance Raman spectroscopy as a powerful characterization tool for materials science. Here we present a short history of Raman scattering research in Brazil, highlighting the important contributions to the field coming from Brazilian researchers in the past. Next we discuss recent and important contributions where Brazil has become a worldwide leader, that is on the physics of quasi-one dimensional carbon nanotubes. We conclude this article by presenting results from a very recent resonance Raman study of exciting new materials, that are strictly one-dimensional carbon chains formed by the heat treatment of very pure double-wall carbon nanotube samples. O Brasil desempenhou um papel importante no desenvolvimento e no uso da espectroscopia Raman como uma ferramenta poderosa na ciência dos materiais. Apresentaremos aqui uma breve história da pesquisa sobre espalhamento Raman no Brasil, enfatizando as contribuições importantes neste campo realizadas por pesquisadores brasileiros no passado. Em seguida, discutiremos contribuições recentes e importantes onde o Brasil se tornou um líder mundial, ou seja na física dos sistemas unidimensionais chamados nanotubos de carbono. Concluímos este artigo apresentando resultados de um estudo muito recente de um novo material que são cadeias de carbono estritamente unidimensionais formadas pelo tratamento térmico de amostras muito puras de nanotubos de carbono de duas camadas.

Strong chemical activity and extreme instability in ambient conditions characterize carbyne, an infinite sp1 hybridized carbon chain. As a result, much less has been explored about carbyne as compared to other carbon allotropes such as fullerenes, nanotubes and graphene. Although end-capping groups can be used to stabilize carbon chains, length limitations are still a barrier for production, and even more so for application. We report a method for the bulk production of long acetylenic linear carbon chains protected by thin double-walled carbon nanotubes. The synthesis of very long arrangements is confirmed by a combination of transmission electron microscopy, X-ray diffraction and (near-field) resonance Raman spectroscopy. Our results establish a route for the bulk production of exceptionally long and stable chains composed of more than 6,000 carbon atoms, representing an elegant forerunner towards the final goal of carbyne’s bulk production., This work was supported by the Austrian Science Fund (FWF, NanoBlends I 943–N19). L.S. acknowledges the scholarship supported by the China Scholarship Council. K.S. and Y.N. acknowledge the JST Research Acceleration Programme. J.K. and J.C.M. acknowledge financial support by the European Research Council Starting Grant No. 336453-PICOMAT. J.K. acknowledges FWF for funding through project MA14-009, as well as Vienna Scientific Cluster for computational time, and he also thanks G. Kresse and M. Marsman for their help in DFT calculations. S.C. acknowledges financial support from the Marie Curie Grant FP7-PEOPLE-2013-IEF project ID 628876. A.R. acknowledges financial support by the European Research Council Advanced Grant DYNamo (ERC-2010-AdG-267374), POCAONTAS (FP7-PEOPLE-2012-ITN No. 316633), MINECO (FIS2013-46159-C3-1-P), Grupo Consolidado UPV/EHU del Gobierno Vasco (IT578-13), AFOSR Grant No. FA2386-15-1-0006 AOARD 144088, and COST Action MP1306 (EUSpec). Z.J.L. and L.N. acknowledge Swiss National Science Foundation (CR2212-152944).

The ultrafast spontaneous electron-density fluctuation dynamics in molecules is studied theoretically by off-resonant multiple X-ray diffraction events. The time- and wavevector-resolved photon-coincidence signals give an image of electron-density fluctuations expressed through the four-point correlation function of the charge density in momentum space. A Fourier transform of the signal provides a real-space image of the multipoint charge-density correlation functions, which reveal snapshots of the evolving electron density in between the diffraction events. The proposed technique is illustrated by ab initio simulations of the momentum- and real-space inelastic scattering signals from a linear cyanotetracetylene molecule.