High Pressure Studies of the Raman-Active Phonons in Carbon Nanotubes

Venkateswaran, U. D.; Brandsen, E. A.; Schlecht, U.; Rao, Apparao M.; Richter, Ernst; Loa, I.; Syassen, K.; Eklund, P. C.

doi:10.1002/1521-3951(200101)223:1<225::aid-pssb225>3.0.co;2-6

Cited by 83 publications

(91 citation statements)

References 34 publications

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“…33 In one experiment on arc-discharge SWNT bucky paper, 50 the R mode could be followed up to 7 GPa, but a discontinuous drop in intensity was observed near 2 GPa (Fig. 5).…”

Section: R-mode Disappearancementioning

confidence: 99%

“…The reanalysis showed that the curvature of the tangential-band energy shift could possibly be interpreted as a change in slope of the wavenumber shift near 2 GPa. 50 The most intense component of the T band then exhibits a shift of 7.5 cm 1 GPa 1 in the range 0-2 GPa and a smaller shift of 4.8 cm 1 GPa 1 in the range 2-5.5 GPa (Table 1). These observations were the first indications of a subtle structural transition in the nanotube bundles near 2 GPa that will be discussed in detail below.…”

Section: Structural Transition At 2 Gpamentioning

confidence: 99%

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Raman spectroscopy on carbon nanotubes at high pressure

Loa

2003

J Raman Spectroscopy

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Raman spectroscopy has been the most extensively employed method to study carbon nanotubes at high pressures. This review covers reversible pressure-induced changes of the lattice dynamics and structure of single- and multi-wall carbon nanotubes as well as irreversible transformations induced by high pressures. The interplay of covalent and van-der-Waals bonding in single-wall nanotube bundles and a structural distortion near 2 GPa are discussed in detail. Attempts of transforming carbon nanotubes into diamond and other "superhard" phases are reviewed critically.Comment: 33 pages, 20 figures, review article, to appear in J. Raman Spectroscop

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“…33 In one experiment on arc-discharge SWNT bucky paper, 50 the R mode could be followed up to 7 GPa, but a discontinuous drop in intensity was observed near 2 GPa (Fig. 5).…”

Section: R-mode Disappearancementioning

confidence: 99%

Section: Structural Transition At 2 Gpamentioning

confidence: 99%

Raman spectroscopy on carbon nanotubes at high pressure

Loa

2003

J Raman Spectroscopy

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“…Such an assumption is reasonable as the polymer wraps around the nanotube and this adsorption is very strong both in water and in film but the interaction between the nanotube and DNA in the solid state is stronger. According to results of investigations on the external pressure effect on RR spectra of carbon nanotubes [48,49], the G + band is shifted to the high-frequency region upon pressure onto the nanotube. In any case, the upshift of G mode frequency indicates that C-C bond force constant of nanotubes in film with DNA becomes stronger relatively to this constant in bundles.…”

Section: Tangential Mode Of Nanotubesmentioning

confidence: 99%

Raman spectroscopy of DNA-wrapped single-walled carbon nanotube films at 295 and 5K

Karachevtsev

Glamazda

2010

Low Temperature Physics

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Resonance Raman spectra of DNA-wrapped single-walled carbon nanotubes films were studied at 5 and 295 K in the range of radial-breathing (175-320 cm -1 ) and tangential (1520-1625 cm -1) modes. The spectra were compared with those of nanotubes in bundles. At 5 K in the spectrum of film an upshift of bands regard to their spectrum at high temperature and the intensity redistribution among bands of two samples were observed. The magnitude of this upshift depends on the nanotube type. The influence of temperature lowering, the environment and the electron-phonon coupling on the Raman spectrum of nanotubes are discussed.

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“…The observed shifts in the Raman spectra show a uniform, average pressure slope. In metallic nanotubes split pressure slopes were found experimentally [4].These results on single walled tubes (SWNT) were complemented by measurements on multiwalled tubes (MWNT) by Thomsen et al [5] and, recently again by Venkateswaran et al [6]. Both groups found the MWNT to have smaller pressure slopes (2.7 and 2.4 TPa À1 , respectively, for the normalized pressure derivatives) than the single walled tubes (3.7 TPa À1 ) [2].…”

mentioning

confidence: 99%

“…For a nice compilation of the Raman pressure work on nanotubes see Ref. [6].The purpose of this note is to extend our analysis of the elastic properties of single and multiwalled nanotubes which is based on elasticity theory, to the recent results of Venkateswaran et al[6] on multiwalled nanotubes and explain their experimental findings. They reported two types of measurements on MWNT with two different pressure media, first the usual 4 : 1 mixture of methanol/ethanol and secondly He, and they find that the pressure slopes are nearly the same, the one for He as pressure medium being slightly smaller (2.4 and 2.3 TPa À1 ).…”

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The Pressure Dependence of the High-Energy Raman Modes in Empty and Filled Multiwalled Carbon Nanotubes

Thomsen

Reich

2001

phys. stat. sol. (b)

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The pressure dependence of the Raman-active modes in carbon nanotubes has become of interest because it revealed a number of unforeseen experimental results. Among the surprises were a large logarithmic pressure dependence of the low-energy radial breathing mode and a lack of different pressure slopes in the high-energy region for the various modes of semiconducting nanotubes [1,2]. The former implied a significant influence of neighboring tubes in a bundle which was described by a van-der-Waals interaction. The latter effect turned out to be a consequence of the missing mirror planes in a general chiral nanotube. Its eigenvectors cannot simply be classified as axial and circumferential; instead, chiral tubes have more complicated eigenvectors, which have been calculated with ab initio methods recently [3]. The observed shifts in the Raman spectra show a uniform, average pressure slope. In metallic nanotubes split pressure slopes were found experimentally [4].These results on single walled tubes (SWNT) were complemented by measurements on multiwalled tubes (MWNT) by Thomsen et al. [5] and, recently again by Venkateswaran et al. [6]. Both groups found the MWNT to have smaller pressure slopes (2.7 and 2.4 TPa À1 , respectively, for the normalized pressure derivatives) than the single walled tubes (3.7 TPa À1 ) [2]. For a nice compilation of the Raman pressure work on nanotubes see Ref. [6].The purpose of this note is to extend our analysis of the elastic properties of single and multiwalled nanotubes which is based on elasticity theory, to the recent results of Venkateswaran et al.[6] on multiwalled nanotubes and explain their experimental findings. They reported two types of measurements on MWNT with two different pressure media, first the usual 4 : 1 mixture of methanol/ethanol and secondly He, and they find that the pressure slopes are nearly the same, the one for He as pressure medium being slightly smaller (2.4 and 2.3 TPa À1 ). For He as a pressure medium one would believe that it easily fills the inner core of the nanotube while the larger methanol/ethanol molecules remain mostly outside or at least are not effective in transmitting the applied hydrostatic pressure to the interior of the nanotube. We make now the approximation that He as pressure medium makes the nanotube look like a hollow cylinder with a finite wall thickness and open ends, and the methanol/ethanol mixture makes it appear as the same cylinder with closed ends. Within elasticity theory the ratio of axial strains for a given hydrostatic pressure is given by [5] u open zz u closedwhere R 1 and R 2 are the inner and outer radius of the MWNT at ambient pressure. As is shown in [5] this result does not change for a circumferential mode, and is thus valid for chiral tubes as well. Equation (1) is independent of any elastic constant of the nanotube since only the pressure medium changed for otherwise identical tubes. For the values cited by Ref.[6] for the radii of their tubes (R 1 ¼ 25-35 A, R 2 ¼ 100-125 A) 1 ), Eq. (1) predicts a reduction to ...

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High Pressure Studies of the Raman-Active Phonons in Carbon Nanotubes

Cited by 83 publications

References 34 publications

Raman spectroscopy on carbon nanotubes at high pressure

Raman spectroscopy on carbon nanotubes at high pressure

Raman spectroscopy of DNA-wrapped single-walled carbon nanotube films at 295 and 5K

The Pressure Dependence of the High-Energy Raman Modes in Empty and Filled Multiwalled Carbon Nanotubes

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