Carbon Raman spectra

An analysis of the literature of RMS has aided considerably in the search for an acceptable structural model of isotropic microporous carbons. Raman spectra of carbons contain two bands of major interest, namely the D-band ( I350cm ) and the G-band ( I580cm ). The D-band is identified with Defective or Disorganized carbon, and the G-band with Graphitic carbon. 

To substantiate that the supports consist of (graphitic) carbon, Raman-spectra were recorded for various samples. An illustrative spectmm is shown for the iron loaded sample pyrolyzed at 800°C (Figure 8, see also Figure 1). The spectmm contains two strong peaks at 1344 cm" and 1584 cm". The peak at 1584 cm", called the G band, is due to in-plane bond stretching of pairs of sp hybridized C-atoms in graphitic planes. 

Solutions of dinitrogen pentoxide in nitric acid or sulphuric acid exhibit absorptions in the Raman spectrum at 1050 and 1400 cm with intensities proportional to the stoichiometric concentration of dinitrogen pentoxide, showing that in these media the ionization of dinitrogen pentoxide is complete. Concentrated solutions in water (mole fraction of NgOg > 0-5) show some ionization to nitrate and nitronium ion. Dinitrogen pentoxide is not ionized in solutions in carbon tetrachloride, chloroform or nitromethane. ... 

Nitrophenyl groups covalently bonded to classy carbon and graphite surfaces have been detected and characterized by unenhanced Raman spectroscopy in combination with voltammetry and XPS [4.292]. Difference spectra from glassy carbon with and without nitrophenyl modification contained several Raman bands from the nitrophenyl group with a comparatively large signal-to-noise ratio (Fig. 4.58). Electrochemical modification of the adsorbed monolayer was observed spectrally, because this led to clear changes in the Raman spectrum. 

The Raman spectrum in Fig. 10 for solid Ceo shows 10 strong Raman lines, the number of Raman-allowed modes expected for the intramolecular modes of the free molecule [6, 94, 92, 93, 95, 96, 97]. As first calculated by Stanton and Newton [98], the normal modes in molecular Ceo above about 1000 cm involve carbon atom displacements that are predominantly tangential... 

Fig. 23. Experimental room temperature Raman spectrum from a sample consisting primarily of bundles or ropes of single-wall nanotubes with diameters near that of the (10,10) nanotube. The excitation laser wavelength is 514.5 nm. The inset shows the lineshape analysis of the vibrational modes near 1580 cm . SWNT refers to singlewall carbon nanotubes [195].

Similar results were found by Bacsa el al. [26] for cathode core material. Raman scattering spectra were reported by these authors for material shown in these figures, and these results are discussed below. Their HRTEM images showed that heating core material in air induces a clear reduction in the relative abundance of the carbon nanoparticles. The Raman spectrum of these nanoparticles would be expected to resemble an intermediate between a strongly disordered carbon black synthesized at 850°C (Fig. 2d) and that of carbon black graphitized in an inert atmosphere at 2820°C (Fig. 2c). As discussed above in section 2, the small particle size, as well as structural disorder in the small particles (dia. —200 A), activates the D-band Raman scattering near 1350 cm . ... 

Fig. 11. Raman spectrum (T = 300 K) of arc-derived carbons containing single-wall nanotubes generated in a Ni/Co-catalyzed dc arc (after ref. [42 ).

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. 

This broad band at 1500 cm was ascribed by Kaufman. Metin, and Saper-stein [10], to an IR observation of the amorphous carbon Raman D and G bands. This is forbidden by the selection rules, and has been attributed to the symmetry breaking introduced by the presence of CN bonds in the amorphous network. As carbon and nitrogen have different electronegativities, the formation of CN bonds gives the necessary charge polarity to allow the IR observation of the collective C=C vibrations in the IR spectrum. This conclusion was stated by the comparison of spectra taken from films deposited from N2 and N2. In the N2-film spectrum, no shift was observed for the 1500-cm band, whereas all other bands shifted as expected from the mass difference of the isotopes. Figure 25 compares... 

Above the eutectic temperature in the iron-FcsC system (1130°C)12, growth of large graphite plates and flakes occurs from the liquid phase. Carbon precipitates in the form of highly ordered graphite crystals from molten iron supersaturated with carbon. The Raman spectrum for chlorination at 1200°C is shown in Fig. 2c. A very strong and narrow... 

Raman scattering is one of the most useful and powerful techniques to characterize carbon nanotube samples. Figure 15.17 shows the Raman spectrum of a single SWNT [127]. The spectrum shows four major bands which are labeled RBM, D, G, and G. ... 

In another example [56] SWNT was modified with peroxytrifluoroacetic add (PTFAA). Raman spectrum of the carbon nanotubes after the FIFA A treatment shows a D-line substantially increased indicating the formation of defect sites with sp3-hybridized carbon atoms on the sidewalls due to the addition of the functional groups. The RBM bands in the region of 170-270cm-1 decreased and shifted to higher... 

With the aid of a bi-functionalized reagent (terminated with pyrenyl unit at one end and thiol group at the other end), gold nanoparticles were self-assembled onto the surface of solubilized carbon nanotubes [147], Raman spectrum of the gold nanoparticle bearing CNTs is enhanced possibly due to charge transfer interactions between nanotubes and gold nanoparticles. 

Figure 9.28 Raman spectrum of green malachite pigment (basic copper(II) carbonate CuC03 Cu (OH)2 taken from the Lucka Bible, now in the Czech Republic. The sample came from an initial I from Genesis chapter 1, Inprincipio. .. ( In the beginning. .Reproduced with permission by Professor Robin Clarke frs, University of London...

The vibration-rotation gas-phase Raman spectrum of C3 O2 was obtained for the first time by Smith and Barrett using a 2-watt argon-ion laser. The results of this experiment gave new information about the bonding potential function for the central carbon bonding fundamental. 

Figure 7.2 Complete Raman spectrum of carbon tetrachloride, illustrating the Stokes Raman portion (on left, negative shifts), Rayleigh scattering (center, 0 shift), and the anti-Stokes Raman portion (on right, positive shifts). Reprinted from Nakamoto (1997) [7] and used by permission of John Wiley Sons, Ltd., Chichester, UK.

Diamond is crystallized in cubic form (O ) with tetrahedral coordination of C-C bonds around each carbon atom. The mononuclear nature of the diamond crystal lattice combined with its high symmetry determines the simplicity of the vibrational spectrum. Diamond does not have IR active vibrations, while its Raman spectrum is characterized by one fundamental vibration at 1,332 cm . It was found that in kimberlite diamonds of gem quality this Raman band is very strong and narrow, hi defect varieties the spectral position does not change, but the band is slightly broader (Reshetnyak and Ezerskii 1990). 

Stoicheff investigated the pure rotational Raman spectrum of CS2. The first few lines could not be observed because of the width of the exciting line. The average values of the Stokes and anti-Stokes shifts for the first few observable lines (accurate to 0.02 cm-1) are Ap = 4.96, 5.87, 6.76, 7.64, and 8.50 cm-1, (a) Calculate the C=S bond length in carbon disulfide. (Assume centrifugal distortion is negligible. The rotational Raman selection rule for linear molecules in 2 electronic states is AJ = 0, 2.) (b) Is this an R0 or Re value (c) Predict the shift for the 7 = 0—>2 transition. 

Fig. 1. Stokes and anti-Stokes Raman spectrum of carbon tetrachloride...

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