Raman spectra diamond

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). 

The Second-Order Raman Spectrum of IJC Diamond An Introduction to Vibrational Spectroscopy of the Solid State 32... 

Fig. 11.3. Raman spectrum of boron-dopedpotycrystaUine diamond showing metallic conductivity. Excitation line ro aser was 514.51...

To evaluate the crystallinity of the films, Raman spectroscopy is used. A typical Raman spectrum is presented in Fig. 4. Of the crystalline diamond, a narrow peak at a frequency of 1332 cur1 is characteristic, which is caused by the first-order phonon scattering by the crystal lattice. The non-diamond carbon is represented in the spectrum by two diffuse bands at ca. 1350 and 1550 cm-1. When comparing the peaks height, one should keep in mind that the Raman signal is 50 times more sensitive to the non-diamond carbon than to the crystalline diamond [20], In the high-quality diamond films used as electrodes, the non-diamond carbon component rarely exceeds 1%. Raman spectroscopy data have been corroborated by the independent impedance spectroscopy measurements (see below). According to [21], the inner layer of a diamond film is enriched with the admixture of non-diamond carbon as compared to its outer layer. 

Fig. 6.2 Raman spectrum of boron-doped diamond film on silicon (a) silicon, (b) boron atoms, (c) diamond (sp3 carbon), and (d) other carbon forms (amorphous)...

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. 

We have developed solvothermal synthesis as an important method in research of metastable structures. In the benzene-thermal synthesis of nanocrystalline GaN at 280°C through the metathesis reaction of GaClj and U3N, the ultrahigh pressure rocksalt type GaN metastable phase, which was previously prepared at 37 GPa, was obtained at ambient condition [5]. Diamond crystallites were prepared from catalytic reduction of CCI4 by metallic sodium in an autoclave at 700°C (Fig.l) [6]. In our recent studies, diamond was also prepared via the solvothermal process. In the solvothermal catalytic metathesis reaction of carbides of transition metals and CX4 (X = F, Cl, Br) at 600-700°C, Raman spectrum of the prepared sample shows a sharp peak at 1330 cm" (Fig. 1), indicating existence of diamond. In another process, multiwalled carbon nanotubes were synthesized at 350°C by the solvothermal catalytic reaction of CgCle with metallic potassium (Fig. 2) [7]. 

A laser Raman spectrum typical of natural diamond, i.e., the presence of the Raman active line at 1332 cm. ... 

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... 

It is of interest that in the Raman spectrum [363], there was no evidence on the presence of diamond (1332cm ), and the spectrum was rather typical of a carbon material, as seen in Figure 11.56. 

Figure A.l. Typical Raman spectrum of polycrystalline diamond [325].

Fig. 7.14. XRD pattern (a), Raman spectrum (b) and SEM image (c) of the diamond sample synthesized by the reduction-pyrolysis-catalysis route.

FIGURE 3.9 (a) Raman spectrum (A. = 514.5nm) of the carbyne deposit shown in Figure 3.7. Top spectrum as-measured, bottom spectrum baseline subtracted and deconvoluted. (b) UV-Raman spectrum (X = 325nm) recorded at different surface points of the carbyne deposit shown in Figure 3.7. The inset shows the down-shifting of the diamond peak position from 1332 to 1328 cm with decreasing crystallite size. 

FIGURE 5.4 SEM image and Raman spectrum of diamond film obtained by the combustion flame method t= 1.05. 

The carbon films obtained were diamond crystals (Figure 5.4(a)). The diamond crystals present predominantly a (111) facet. Raman spectrum of the film is shown in Figure 5.4(b). The sharp peaks due to diamond detected at 1335 cm showed the good quality of diamond. The average crystal size is about 10 pm. The influence of the ratio of acetylene to oxygen and of substrate temperature on the qualities and orientation of diamond have been discussed in a previous paper [33]. 

We now present temperature measurements of the vibrational properties of the T) phase. Type II diamonds were used for mid-IR measurements to avoid interference with the characteristic absorption of the sample. The representative absorption spectra at different temperatures (see Fig. 14) clearly show the presence of a broad 1700 cm IR band (compare with Fig. 12). Its presence was also observed in the sample heated to 495 K at 117 GPa (see below). The position of the band and its damping (if fitted as one band) does not depend on pressure and temperature within the error bars. The Raman spectrum of the Tj phase obtained on heating (see below) does not show any trace of the molecular phase (see Fig. 12(b)). Careful examination of the spectrum in this case showed a weak broad band at 640 cm and a shoulder near 1750 cm (both indicated by arrows in Fig. 12(b)). For an amorphous state, the vibrational spectrum would closely resemble a density of phonon states [63] with the maxima corresponding roughly to the zone boundary acoustic and optic vibrations of an underlying structure [3-5, 55], which is consistent with our observations. The only lattice dynamics... 

Figure 6.26 Raman spectrum of an ultrananocrystalline diamond film at different excitation wavelengths ( Elsevier 2000).

Let us illustrate this conversion. The Raman spectrum of diamond shows a sharp band at 1331 cm. Assuming RLW = 9394 cm this band appears at 8063 cm in the single channel spectrum. As another example. Fig. 10.25 shows both types of spectra for ethanol on the left there is the Raman spectrum over the range from 100 to 3500 cm and on the right the single channel spectrum between 5894 and 9294 cm . Notice that the spike at 9394 cm is due to the laser line. 

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