Raman spectra of graphite

Laser Raman spectroscopy complements ssNMR in characterizing the different types of carbonaceous structures formed in the charred materials. Indeed, in the Raman spectra of graphite, there are many features that can be identified and that can provide information about the properties of the materials, such as their electronic structure as well as information about imperfections or defects. Since mechanical, elastic, and thermal properties of graphite are influenced by its structure, Raman spectra could provide interesting information regarding the carbonization process.1617... 

Canfado LG, Pimenta MA, Neves BRA, Dantas MSS, Jorio A (2004) Influence of the atomic structure on the Raman spectra of graphite edges. Phys Rev Lett 93 247401... 

Figure 9.37 Raman spectra of graphite and graphite intercalation compounds (GIC) with FeCl3. A lower stage number indicates a higher degree of intercalation.

Kudin KN, Ozbas B, Schniepp HC, Prud homme RK, Aksay lA, Car R (2008) Raman spectra of graphite oxide and functionalized graphene sheets. Nano Lett 8 36-41... 

Katagiri G, Ishida H, Ishitani H (1988) Raman spectra of graphite edge planes. Carbon 26 565-571... 

Figure 13 Raman spectra of graphite exited by laser lines with photon energies indicated [40]. (Reproduced from Journal of non-crystalline solids, 227-30, Pocsik, L, et al.. Origin of the D peak in the Raman spectrum of microcrystalline graphite, pp. 1083-1086. Copyright 1998, with permission from Elsevier Science.)... 

N.J. Everall, J. Lumsdon, D.J. Christopher, The effect of laser-induced heating upon the vibrational raman spectra of graphites and carbon fibres. Carbon 29(2), 133-137 (1991)... 

Raman Microspectroscopy. Raman spectra of small soflds or small regions of soflds can be obtained at a spatial resolution of about 1 p.m usiag a Raman microprobe. A widespread appHcation is ia the characterization of materials. For example, the Raman microprobe is used to measure lattice strain ia semiconductors (30) and polymers (31,32), and to identify graphitic regions ia diamond films (33). The microprobe has long been employed to identify fluid iaclusions ia minerals (34), and is iacreasiagly popular for identification of iaclusions ia glass (qv) (35). 

Fig. 7. First-order Raman spectra of (a) graphite, (b) inner core material containing nested nanotubes, (e) outer shell of carbonaceous cathode deposit (after ref. [24]).

Fig. 3 shows the Raman spectra of the MWNT samples as a flmction of helium pressure. The peaks around 1280 cm", called the D-mode, are Imown to be attributed la amorphous carbons and defects of nanotubes, whereas the pe around 1600 cm", called the G-mode, are known to be due to the graphitic structure of carbon atoms. The G-mode of produced MWNTs was shifted to a lower wave number region (1595 cm" ) by the strain of the forming tube [6]. The intensity of MWNTs synftiesized under 250 Torr was lower than at other pressure. And the ratio of the G-mode to the D-mode was the hi t at pressure of 500 Torr. The highest purity of MWNTs was obtained when the pressure of helium is 500 Torr. 

Fig. 5 shows typical Raman spectrum for SWNTs, the Raman spectra of SWNTs have fingerprint features, which is quite different fi om those of graphite, MWNTk and amorphous carbon. 

Fig. 2.4 Typical Raman spectra of (a) graphite, with peaks labeled as discussed in the text (b) graphene (liquid-phase exfoliated). Inset Evolution of 2D-band with increasing layer numbers [120],...

In situ Raman spectra studies performed on graphite anodes also seem to reveal a cointercalation occurrence that leads to exfoliation. Huang and Freeh used solutions of LiC104 in EC/EMC and EC/DME as electrolytes and monitored the E2g2 band at 1580 cm in the Raman spectra of the graphite that was cycled between 2.0 and 0.07 Reversible lithium intercalation and deintercalation was indicated by... 

FIGURE 6.13 The Raman spectra of E2g2 graphitic intralayer mode in FeCl3 GICs depending on stage index (From Underhill, C., et al., Solid State Commun. 29, 769, 1979. With permission.)... 

The fullerenes, Cgo and C70, are produced in the laboratory by the contact arc-evaporation of 6 mm graphite rods (e.g. Johnson Matthey, spectroscopic grade) in 100 torr of helium in a water-cooled stainless steel chamber described previously [5]. The soluble material in the soot produced from the arc-evaporation is extracted with toluene using a Soxhlet apparatus. The pure fullerenes are obtained by chromatography on neutral alumina columns using hexanes as the eluant, or by the use of a simple filtration technique using charcoal-silica as the stationary phase and toluene as the eluant [5]. The fullerenes so prepared are characterized by UV/Vis spectroscopy and other techniques. FT-IR spectra of vacuum deposited fullerene films on KBr crystals also provide a means of characterization, just as do Raman spectra of films deposited on a silicon crystal. Ultraviolet and X-ray photoelectron spectra of fullerene films on... 

As a typical example, Figure 12.15 shows the Raman spectra of an unfilled ethylene-propylene-diene rubber (EPDM). The Raman spectra of pure MWNTs, pure CB and of a EPDM / MWNTs composite are also given. The D, G and G bands are respectively located at 1348, 1577 and 2684 cm-1 in the Raman spectrum of the multiwall carbon nanotubes. The Raman spectrum of pure carbon black (CB) remains dominated by the bands associated with the D and G modes at 1354 and 1589 cm1 respectively, even when the carbons do not have particular graphiting ordering (Figure 12.11). This fact has been widely discussed by Robertson (84) and Filik (85). Amorphous carbons are mixtures of sp3 (as in diamond) and sp2 (as in graphite) hybridised carbon. The it bonds formed by the sp2 carbons being more polarisable than the a bonds formed by the sp3 carbons, the authors conclude that the Raman spectrum is dominated by the sp2 sites. 

Fig. 13. Raman spectra of original graphite (a), 2 min-fluorinated sample at 390 C (b) (reproduced with permission from Electrochim. Acta, 44 (1999) 2879 [48]).

R (= /d//g) values of Raman spectra of surface-fluorinated graphite samples... 

Figure 16 shows the Raman spectrum of a DLC film deposited by the IBAD technique. The Raman spectra for diamond like materials provide information on the sp bonding. The characteristic features of Raman spectra of diamond like materials consist of a graphite-like (G) peak and a disorder (D) peak in the regions 1500-1550 cm and 1330-1380 cm respectively. The relative intensities of the G and D peaks can be used to indicate qualitatively the concentration of graphite crystallites of... 

We have analyzed the influence of the annealing temperature, structural disorder, and the frequency of a continuous excitation laser radiation Vl on the first- and the second-order Raman spectra of several nanostructured carbon materials including single-wall carbon nanotubes (SWCNT), SWCNT-polymer composites, and nanostructured single-crystalline graphites. Consideration of the high-order nonlinear effects in Raman spectra and anharmonicity of characteristic Raman bands (such as G, G, and D modes) provides important information on the vibration modes and collective (phonon-like) excitations in such ID or 2D confined systems... 

Comparative Analysis of Raman Spectra of Carbon Nanotubes and Graphite... 

One can see that G-band is characterized with the highest intensity in the spectra (Fig. 7.6a). It should be noted as well that the SWCNT 2vd band is noticeably higher in intensity in comparison with the main D band, which can be seen from the lower curve 1. Broadband noise is typically not strong in Raman spectra of SWCNT but became more noticeable for the bulk systems (graphite and polymer-SWCNT composite, curves 2 and 3 in the Fig. 7.6a). SWCNT possess also a low-frequency vibration mode at Vrbm 160 cm corresponding to radial oscillations of carbon atoms in plane of the cross section, which exhibits a strong variation with nanotube diameter [7]. The SWCNT vibration spectra show a sum harmonic signal Vg+Vrbm with a spectral shape, which will be discussed below. 

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