Raman peak assignments

NMR and Raman peak assignments for natural gas and non-natural gas hydrates are listed in Tables 6.6 through 6.8, respectively. The NMR data presented are based on the works by Ripmeester and Ratcliffe (1998, 1999) and... 

List of Raman Peak Assignments for Natural Gas Hydrates... 

Silane Compounds FTIR peak assignments (cm ) Raman peak assignments (cm )... 

Fig. 11.2. Representative Raman spectra in the fingerprint region of human tooth enamel and dentin. Peak assignments are marked...

The comparison of our experimental data with those of Ref. (Bini et al. 1998 Bensasson et al. 1997) shows that the Raman spectrum of the high-pressure hydrogenated C60H36 is richer more than five times than that of the transfer hydrogenated C60H36. The majority of the experimentally observed Raman peaks (86 peaks from a total number of 126) are very close, with an accuracy of 5 cm-1, to the calculated frequencies and cross-sections of the Raman active modes (their total number is 400) (Bini et al. 1998). The peaks, which are close to the calculated frequencies, are assigned to all principal isomers, but the majority of them belong to the isomers with the symmetry S6, T and D3d. 

As shown in Figs. 2.10 and 2.11, the Raman spectra of the two polymorphic forms of clopidogrel bisulfate are substantially different. These differences are summarized in Table 2.2, which lists the energies of the main observed peaks and which contrasts the energies of peaks assigned to the same vibrational mode. 

Table II lists the Raman peak positions for samples 4 and 11, which are typical of unbleached lignin-rich wood pulps. These peaks have been assigned in terms of contributions by cellulose and lignin. Raman contributions from hemicelluloses were expected to be broad and to occur at wavenumbers where cellulose contributions were detected. In Table II, certain bands are assigned to specific chemical-group vibrations. The assignment of bands to various groups in cellulose was based on literature [18]. The lignin-related assignments are based on the work described in this paper and the authors unpublished work.

Schotman and co-workers tentatively assigned the new Raman peaks at 1625 and 1592 cm 1 observed during sulfur vulcanisation of squalene, to the formation of conjugated dienes and trienes, respectively [70]. When vulcanisation was carried out in the presence of l,3-di(citraconimidomethyl)benzene, this resulted in a reduced intensity of these two new peaks, corroborating that conjugated dienes and trienes, formed as a result of reversion, react with the diimide. Obviously, the diimide is not an anti-reversion agent in the sense that it prevents reversion, but it is in the sense that it repairs crosslinks when reversion has occurred. 

Ataka and Tanaka (1979) measured both the far-infrared and Raman peaks of crystalline lysozyme, with self-consistent results. They assigned the uniform background to residual water molecules. 

Another disorder-induced Raman peak, known as D band, can be found around 1,620 cm [53]. The D mode does not exist in pure graphite, but is observed for intercalated graphite compounds and MWCNTs. The peak has been assigned to the in-plane vibrations of the outer parts of graphite domains [54, 55]. 

The Raman spectrum of the carbon film shown in Figure 5.6(b) presents one peak at 1460cm and two sharp peaks detected near 1864cm and 2248 cm are assigned to allenic and acetylenic stretching mode of sp-bond carbon chains [35]. The frequency of the Raman peak in the spectra depends on the excitation wavelength and the length of carbon chains in the carbyne. 

The major Raman peak for 10% WO3 on AI2O3 occurs around 970 cm , and has been assigned to the W=0 symmetrical stretch of the surface tungsten oxide species (19,23). The intensities of the major Raman band for WO3 1808 cm" ), Al2(W04)3 (1052 cm ), and 10% WOq on Al2O3 (970 cm ) were compared after normalization with respect to the laser power applied. The relative Raman intensity ratios for these peaks are 1600 40 1 for normalized laser power. These Raman intensity ratios were further scaled for the different tungsten oxide contents and yielded relative ratios of 160 5 1 (15). 

---