Direct Experimental Evidence of Exciton-Phonon Bound States in Carbon Nanotubes

Plentz, F.; Ribeiro, Henrique B.; Jório, Ado; Strano, Michael S.; Pimenta, M. A.

doi:10.1103/physrevlett.95.247401

Cited by 109 publications

(133 citation statements)

References 20 publications

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“…From the value of the zone-edge optical phonon (as measured from the D band Raman line), we deduce that the splitting between this KK 0 exciton and the bright exciton is also on the order of 35 meV for upper sub-bands. This value, very similar to the one reported for S 11 and S 22 [24,28], is quite surprising since this splitting was expected to depend on the diameter and the transition order. We attribute the coincidence to an accidental compensation of the scalings with the diameter and the local dielectric constant.…”

Section: Semi-conducting Nanotubessupporting

confidence: 58%

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Excitonic signatures in the optical response of single‐wall carbon nanotubes

Voisin¹,

Berger²,

Berciaud³

et al. 2012

Physica Status Solidi (b)

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The optical properties of single-wall carbon nanotubes (SWNTs) are dominated by the excitonic character of the transitions even at room temperature. The very peculiar properties of these excitons arise from both the one-dimensional (1D) nature of carbon nanotubes and from the electronic properties of graphene from which nanotubes are made. We first propose a brief qualitative review of the structure of the excitonic manifold and emphasize the role of dark states. We describe recent experimental investigations of this excitonic structure by means of temperature dependent PL measurements. We investigate the case of upper sub-bands and show that high-order optical transitions remain excitonic for large diameter nanotubes. A careful investigation of Rayleigh scattering spectra at the single nanotube level reveals clear exciton-phonon side-bands and Lorentzian line profiles for all semi-conducting nanotubes. In contrast, metallic nanotubes show an ambivalent behavior which is related to the reduced excitonic binding energy.Schematic of the exciton manifold in single-wall carbon nanotubes.

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Section: Semi-conducting Nanotubessupporting

confidence: 58%

“…They lead to phonon-side bands in absorption and PL spectroscopy. Such side-bands have been first reported by several teams [24][25][26][27]. The key point is that these side-bands are not symmetrical (in energy) with respect to the bright state but rather with respect to the KK 0 dark ones (which are degenerate in energy).…”

Section: Excitonsmentioning

confidence: 86%

Excitonic signatures in the optical response of single‐wall carbon nanotubes

Voisin¹,

Berger²,

Berciaud³

et al. 2012

Physica Status Solidi (b)

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“…In this case λ ex corresponds to the energy of the excitonic states eh ii associated with the ith electronic interband transitions E ii (i=1, 2, 3, 4) in the single particle picture [3,17], while λ em is the emission energy of the lowest exciton transition eh 11 . Other spots in Fig.1a are related to excitonphonon sidebands [18,19,20]. The spectral features in Fig.1a are summarized in Fig.2.…”

mentioning

confidence: 90%

“…Notably, these three peaks do not correspond to any of the known exciton-exciton resonances of SWNTs in this spectral range [3,17]. The (980nm, 1118nm) peak is not assigned to a D phonon sideband of (8,4), (7,6) or (9, 4) tubes, due to the lack of such sideband in previous investigations of these and other tubes [18,19,23,24]. Indeed, the excitation energies of the (980nm, 1118nm), (568nm, 1118nm) and (346nm, 1118nm) bands match, respectively, the eh 11 , eh 22 and eh 33 transitions of (6,5) tubes [3], whereas their emission around 1118 nm is consistent with (8,4), (7,6), (9, 4) eh 11 .…”

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confidence: 99%

Photoluminescence Spectroscopy of Carbon Nanotube Bundles: Evidence for Exciton Energy Transfer

et al. 2007

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Photoluminescence is commonly used to identify the electronic structure of individual nanotubes. But, nanotubes naturally occur in bundles. Thus, we investigate photoluminescence of nanotube bundles. We show that their complex spectra are simply explained by exciton energy transfer between adjacent tubes, whereby excitation of large gap tubes induces emission from smaller gap ones via Förster interaction between excitons. The consequent relaxation rate is faster than nonradiative recombination, leading to enhanced photoluminescence of acceptor tubes. This fingerprints bundles with different compositions and opens opportunities to optimize them for opto-electronics.

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“…As micelas formadas por surfactante e nanotubos formam dispersões estáveis em meio aquoso. As miscelas mantêm os nanotubos de carbono isolados uns dos outros, permitindo o estudo das propriedades fotofísicas (absorção, emissão, "excitons") de cada nanotubo e a correlação dessas propriedades físicas com a estrutura atômica, ou seja, com os ín-dices n e m [61][62][63] . A interação dos SWNTs com seqüências de oligonucleotídeos (Figura 7) tem sido um dos métodos mais utilizados e com maior sucesso para a separação de nanotubos metáli-cos de nanotubos semicondutores e, também, na separação de nanotubos pelo diâmetro e comprimento 63,64 .…”

Section: Figura 5 Espectros Raman De Nanotubos De Paredes Duplas Purunclassified

Funcionalização de nanotubos de Carbono

Filho

Fagan

2007

Quím. Nova

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Recebido em 28/7/06; aceito em 18/1/07; publicado na web em 25/9/07 FUNCTIONALIZATION OF CARBON NANOTUBES. Carbon nanotubes are very stable systems having considerable chemical inertness due to the strong covalent bonds of the carbon atoms on the nanotube surface. Many applications of carbon nanotubes require their chemical modification in order to tune/control their physico-chemical properties. One way of achieving this control is carrying out functionalization processes where atoms and molecules interact (covalent or non-covalent) with the nanotubes. We review some of the progress that has been made in chemical functionalization of carbon nanotubes. Emphasis is given to chemical strategies, the most used techniques, and applications.Keywords: carbon nanotubes; functionalization; nanomaterials. INTRODUÇÃOOs nanomateriais, em geral, são muito importantes porque se diferenciam de forma dramática dos seus precursores "bulk". As propriedades destes materiais são determinadas pelo tamanho e pela morfologia, originando uma fascinante sintonia em suas propriedades físico-químicas. Talvez os exemplos mais claros e ilustrativos desses fenômenos possam ser tomados da ciência do carbono após a descoberta dos fulerenos, em 1985 1 , e dos nanotubos de carbono, em 1991 2 . Os nanotubos de carbono, assunto dessa revisão, são sistemas modelo para a nanociência e a nanotecnologia. Essas novas estruturas de carbono são bastante versáteis para se integrarem a diferentes áreas do conhecimento e são capazes de promover uma inter/multidisciplinaridade muito forte. Hoje, as pesquisas em nanotubos de carbono cruzam as fronteiras da física, da química, das ciências dos materiais, da biologia e desenvolvem-se rapidamente no campo da farmacologia.Os nanotubos de carbono, quanto ao número de camadas, podem ser classificados em duas formas: nanotubos multicamadas ("multi-wall carbon nanotubes -MWNTs") e camada simples ("single-wall carbon nanotubes -SWNTs"). Um tipo especial de MWNT é o nanotubo de parede dupla ("double-wall carbon nanotubes -DWNTs"). Uma ou outra forma de nanotubos apresenta-se mais apropriada dependendo da aplicação desejada. Os MWNTs foram observados pela primeira vez por Iijima 2 , em 1991. Dois anos depois, em contribuições independentes, Iijima e colaboradores 3 no Japão e Bethune e colaboradores 4 nos EUA publicaram simultaneamente a síntese dos SWNTs. Recentemente debate-se a quem devem ser atribuídos os créditos da descoberta dos nanotubos de carbono 5 . Entretanto, não há dúvidas que a área de pesquisa em nanotubos consolida-se após o trabalho de Iijima 2 . A Figura 1 mostra imagens de microscopia eletrônica de transmissão (TEM) de MWNTs, DWNTs e SWNTs. O avanço das pesquisas em nanotubos de carbono foi claramente impulsionado pelo desenvolvimento dos processos de síntese, levando à produção de feixes de nanotubos do tipo SWNT com boa qualidade. Esse avanço foi realizado pelo grupo do Prof. Smalley na Rice University 6 e tornou possível a execução de estudos de microscopia 7,8 e de espectroscopia 9 que permitiram...

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Direct Experimental Evidence of Exciton-Phonon Bound States in Carbon Nanotubes

Cited by 109 publications

References 20 publications

Excitonic signatures in the optical response of single‐wall carbon nanotubes

Excitonic signatures in the optical response of single‐wall carbon nanotubes

Photoluminescence Spectroscopy of Carbon Nanotube Bundles: Evidence for Exciton Energy Transfer

Funcionalização de nanotubos de Carbono

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