Raman scattering from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="italic">sp</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>carbon clusters

Yoshikawa, Masanobu; Nagai, Naoto; Matsuki, Michiyasu; Fukuda, Hisashi; Katagiri, Gen; Ishida, Hideyuki; Ishitani, A.; Nagai, Ichiro

doi:10.1103/physrevb.46.7169

Cited by 123 publications

(52 citation statements)

References 21 publications

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“…They proposed that smaller clusters possess higher vibrational frequencies than larger clusters by making an analogy with transpolyacetylene, where the vibrational frequency changes as a function of the conjugation length of polymer chains. 6 A similar effect was reported by Yoshikawa et al 7 and Tamor et al 8 However, no research has been devoted to wavelength-dependent Raman scattering of amorphous silicon carbon materials. Therefore, in this letter, we present the excitation energy-dependent resonant Raman scattering of a-Si:C:H and provide new insight to understand this phenomena exhibited by carbon materials.…”

Section: Introductionsupporting

confidence: 58%

Wavelength-dependent Raman scattering of hydrogenated amorphous silicon carbon with red, green, and blue light excitation

et al. 2003

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The UCD community has made this article openly available. Please share how this access benefits you. Your story matters! (@ucd_oa) Some rights reserved. For more information, please see the item record link above. This study presents results of wavelength-dependent Raman scattering from amorphous silicon carbon (a-Si:C:H). The a-Si:C:H films were produced by radio-frequency plasma-enhanced chemical vapor deposition. Prior results with amorphous carbon indicate that laser excitation selectively probes clusters with differing sizes. Our measurements with a-Si:C:H indicate that when using red (632.8 nm), green (514.5 nm), and blue (488.0 nm) excitation, the Raman D and G peaks shift to higher wave numbers as the excitation energy increases. The higher frequency is associated with smaller clusters that are preferentially excited with higher photon energy. It appears that photoluminescence occurs due to radiative recombination from intracluster transitions in Si-alloyed sp 2 -bonded carbon clusters.

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Section: Introductionsupporting

confidence: 58%

Wavelength-dependent Raman scattering of hydrogenated amorphous silicon carbon with red, green, and blue light excitation

et al. 2003

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“…Raman spectra obtained with the two different scattering geometries, respectively, yielded the depolarization ratio (D p ‫ס‬ I -/I ) for the E 2g2 mode, which is expressed as D p ‫ס‬ 1 for an ideal crystal and 3 ⁄4 for polycrystalline material. 20 The measured values of D p were calibrated against reference peaks of carbon tetrachloride, which show complete depolarization (D p ‫ס‬ 0.75) at the 218-and 314-cm −1 Ramanactive lines of CCl 4 . 21 The powder resistivity and the performance of the undoped and boron-doped S-VGCFs as an anode material in litherium ion batteries were evaluated.…”

Section: Methodsmentioning

confidence: 99%

Structural Characterization of Boron-doped Submicron Vapor-grown Carbon Fibers and Their Anode Performance

et al. 2000

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Structural evolution of undoped and boron-doped submicron vapor-grown carbon fibers (S-VGCFs) was monitored as a function of heat-treatment temperature (HTT). Based on x-ray and Raman data, over the range of HTT from 1800 to 2600 °C, it was found that boron atoms act as catalysts to promote graphitization due to boron's higher diffusivity. For the range of HTT from 2600 to 2800 °C, the process of boron out-diffusion from the host material induces defects, such as tilt boundaries; this process would be related with the improved capacity and Coulombic efficiency of boron-doped S-VGCFs. When 10 wt% S-VGCFs was used as an additive to synthetic graphite, the cyclic efficiency of the capacities was improved to almost 100%.

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“…does not provide a good representation of the PDOS [50]. Since the local sp 2 -bonded carbon energy gap of $2 eV is comparable to the energy of visible Raman excitation, the sp 2 -bonded carbon network exhibits electronic p-p* transition resonance enhancement in the Raman cross-section [43,[48][49][50]. On the other hand, sp 3 -bonded carbon does not exhibit such a resonance effect because of the higher local gap of $5.5 eV.…”

Section: Raman Spectroscopymentioning

confidence: 92%

“…It has been extensively used for the characterization of diamond [41][42][43][44], graphite [45], and diamond-like carbon (DLC) [42,43,[46][47][48][49]. Raman scattering is the most popular technique for identifying sp 3 bonding in diamond and sp 2 bonding in graphite and DLC.…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…Nonetheless, the 514-nm-excited Raman spectra do not exhibit a clear diamond peak at 1332 cm À1 , although the peak due to the sp 3 sp 2 -bonded carbon network is resonantly enhanced under visible excitation [43,[48][49][50], which consequently causes the 1332 cm À1 diamond peak to overlap with the peaks due to sp 2 -bonded carbon. The suppression of the resonance Raman effect, which was dominant in the 514 nm excitation, and the possible increase in the signal from sp 3 -bonded carbon are expected to occur at higher photon energies.…”

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confidence: 99%

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Plasma-enhanced chemical vapor deposition of nanocrystalline diamond

Okada¹

2007

Science and Technology of Advanced Materials

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Nanocrystalline diamond films have attracted considerable attention because they have a low coefficient of friction and a low electron emission threshold voltage. In this paper, the author reviews the plasma-enhanced chemical vapor deposition (PE-CVD) of nanocrystalline diamond and mainly focuses on the growth of nanocrystalline diamond by low-pressure PE-CVD. Nanocrystalline diamond particles of 200-700 nm diameter have been prepared in a 13.56 MHz low-pressure inductively coupled CH 4 /CO/H 2 plasma. The bonding state of carbon atoms was investigated by ultraviolet-excited Raman spectroscopy. Electron energy loss spectroscopy identified sp 2 -bonded carbons around the 20-50 nm subgrains of nanocrystalline diamond particles. Plasma diagnostics using a Langmuir probe and the comparison with plasma simulation are also reviewed. The electron energy distribution functions are discussed by considering different inelastic interaction channels between electrons and heavy particles in a molecular CH 4 /H 2 plasma. r

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Raman scattering fromsp2carbon clusters

Cited by 123 publications

References 21 publications

Wavelength-dependent Raman scattering of hydrogenated amorphous silicon carbon with red, green, and blue light excitation

Wavelength-dependent Raman scattering of hydrogenated amorphous silicon carbon with red, green, and blue light excitation

Structural Characterization of Boron-doped Submicron Vapor-grown Carbon Fibers and Their Anode Performance

Plasma-enhanced chemical vapor deposition of nanocrystalline diamond

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