Dielectric screening in polyynes encapsulated inside double-wall carbon nanotubes

Moura, Luciano G.; Fantini, C.; Righi, A.; Zhao, Changhui; Shinohara, Hisanori; Pimenta, M. A.

doi:10.1103/physrevb.83.245427

Cited by 13 publications

(12 citation statements)

References 25 publications

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“…The electronic and vibrational properties of carbyne are greatly influenced by the local environment as has been observed for short polyyne chains in solution [7][8][9][10], in CNTs [11][12][13], and on Ag surfaces [8]. Theoretical models for short colloidal chains show a softening of the Raman frequency that saturates at around 1,900 cm −1 [14,15]; however, Raman frequencies below 1,800 cm −1 have been observed for chains in double-and multi-wall CNTs [16][17][18].…”

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confidence: 93%

“…1: Raman response of polyynes as a function of inverse length, given by the number N of carbon atoms. The solid lines are linear fits to the available data on chains with assigned lengths (upper solid line: colloidal chains [7-10], lower solid line: chains inside CNTs [11][12][13], dashed blue line: extrapolation to infinite chains). The black dashed line shows theoretical SCS-MP2 results [4].…”

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confidence: 99%

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Polyyne electronic and vibrational properties under environmental interactions

et al. 2016

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Recently the novel system of linear carbon chains inside double-walled carbon nanotubes has extended the length of sp1 hybridized carbon chains from 44 to thousands of atoms [Shi et al., Nat. Mater. 15, 634 (2016)]. The optoelectronic properties of these ultralong chains are poorly described by current theoretical models, which are based on short chain experimental data and assume a constant environment. As such, a physical understanding of the system in terms of charge transfer and van der Waals interactions is widely missing. We provide a reference for the intrinsic Raman frequency of polyynes in vacuo and explicitly describe the interactions between polyynes and carbon nanotubes. We find that van der Waals interactions strongly shift this frequency, which has been neither expected nor described for other intramolecular C-C stretching vibrations. As a consequence of charge transfer from the tube to the chain, the Raman response of long chains is qualitatively different from the known phonon dispersion of polymers close to the Γ point. Based on these findings we show how to correctly interpret the Raman data, considering the nanotube's properties. This is essential for its use as an analytical tool to optimize the growth process for future applications

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confidence: 93%

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Polyyne electronic and vibrational properties under environmental interactions

et al. 2016

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“…The lower line contains studies all embracing nanotubes taking into account an additional downshift of 60 cm −1 due to the interaction with the inner tubes. The solid symbols are experimental results with confirmed length 21,[40][41][42][43] and the empty symbols correspond to the LLCC@DWCNTs reported in this work and for LLCC@D/MWCNT 19,21 . The partly solid symbols are experimental results with length estimated by TEM.…”

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confidence: 96%

Confined linear carbon chains as a route to bulk carbyne

et al. 2016

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The extreme instability and strong chemical activity of carbyne, the infinite sp 1 hybridized carbon chain, are responsible for its low possibility to survive at ambient conditions. Therefore, much less has been possible to explore about carbyne as compared to other novel carbon allotropes like fullerenes, nanotubes and graphene. Although end-capping groups can be used to stabilize a carbon chain, length limitation is still a barrier for its actual production, and even more for applications. Here, we report on a novel route for bulk production of record long acethylenic linear carbon chains protected by thin double-walled carbon nanotubes. A corresponding extremely high Raman band is the first proof of a truly bulk yield formation of very long arrangements, which is unambiguously confirmed by transmission electron microscopy. Our production establishes a way to exceptionally long stable carbon chains, and an elegant forerunner towards the final goal of a bulk production of essentially infinite carbyne.Different kinds of allotropes can be formed from elemental carbon due to its sp n hybridization 1 . 1 arXiv:1507.04896v2 [cond-mat.mtrl-sci]

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“…Similarly, the screening effect on the carbon chains has also been attributed to the inner tube of the DWCNTs. 46…”

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confidence: 99%

Extraction of Linear Carbon Chains Unravels the Role of the Carbon Nanotube Host

et al. 2018

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Linear carbon chains (LCCs) have been shown to grow inside double-walled carbon nanotubes (DWCNTs), but isolating them from this hosting material represents one of the most challenging tasks toward applications. Herein we report the extraction and separation of LCCs inside single-walled carbon nanotubes (LCCs@SWCNTs) extracted from a double-walled host LCCs@DWCNTs by applying a combined tip-ultrasonic and density gradient ultracentrifugation (DGU) process. High-resolution transmission electron microscopy, optical absorption, and Raman spectroscopy show that not only short LCCs but clearly long LCCs (LLCCs) can be extracted and separated from the host. Moreover, the LLCCs can even be condensed by DGU. The Raman spectral frequency of LCCs remains almost unchanged regardless of the presence of the outer tube of the DWCNTs. This suggests that the major importance of the outer tubes is making the whole synthesis viable. We have also been able to observe the interaction between the LCCs and the inner tubes of DWCNTs, playing a major role in modifying the optical properties of LCCs. Our extraction method suggests the possibility toward the complete isolation of LCCs from CNTs.

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Dielectric screening in polyynes encapsulated inside double-wall carbon nanotubes

Cited by 13 publications

References 25 publications

Polyyne electronic and vibrational properties under environmental interactions

Polyyne electronic and vibrational properties under environmental interactions

Confined linear carbon chains as a route to bulk carbyne

Extraction of Linear Carbon Chains Unravels the Role of the Carbon Nanotube Host

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