Poly from Raman spectrum

Structure of Poly iodine from the Resonance Raman Spectrum.Ill... 

There are few methods suitable for on-line chemical analysis of aerosol particles. Raman spectroscopy offers the possibility of identifying the chemical species in aerosol particles because the spectrum is specific to the molecular. structure of the material, especially to the vibrational and rotational modes of the molecules. Raman spectra have been obtained for individual micron-sized particles placed on surfaces, levitated optically or by an eiectrodynamic balance, or by monodisperse aerosols suspended in a flowing gas. A few measurements have also been made for chemically mixed and poly disperse aerosols. The Raman spectrum of a spherical particle differs from that of the bulk material because of morphology-dependent resonances that re.su It when the Raman scattered photons undergo Mie scattering in the particle. Methods have been developed for calculating the modified spectra (McNulty el al., 1980). 

Raman microspectroscopy studies indicate that the spectra from hardness impressions in SiC and those from the pristine surface outside the indentation area are significantly different [4, 134], This is illustrated in Figure 48 for a polycrystalline chemical-vapor deposited (CVD) 3C SiC film. The results for a single crystal 2H poly type of SiC are essentially the same [134], except for the extra line at 770 cm" in the Raman spectrum of pristine 2H SiC, related to the splitting of the TO(T) modes in hexagonal 2H as compared to the cubic 3C SiC [226]. This indicates that the deformation mechanism during indentation of SiC is independent of its microstructure prior to loading. Comparison of a typical spectrum... 

Figure 5-5. Raman spectrum of -poly(L-alanine). (From [89])...

Raman spectrum and photoluminescence of poly (2,5 bis (2-thienyl) 3-alkylthiophene) In this chapter the polymers are denoted pA3Th-C or pA3Th-E ( is defined in Table 14.16, C(E) refers to chemical (electrochemical) oxidative polymerization). The Raman analysis developed for polythiophene cannot be strictly applied because the Raman spectra are not identical. In particular, the R and p criteria may be redefined. However, some qualitative argimients of this analysis can be used in order to compare polymers prepared from silylated and hydrogenated monomers. 

The CNTs generally exhibit well-defined Raman peaks. It is possible to use Raman peak shift to characterize the load transfer mechanism of the CNT/poly-mer composites. When a strain is applied to a material, the interatomic distances change, leading to variations in the firequeucy of vibrational modes. Accordingly, Raman spectroscopy can provide useful information related to the load transfer between the polymer matrix and CNTs. The Raman spectrum of SWNTs generally shows characteristic peaks located at 1350 cm (D band), 1550-1605 cm (G band) and 2700 cm (D band) [35-37]. The D-band derives from the disorder-induced mode and its second-order harmonic is D (G ) band. The G-band is associated with the graphite-like in-plane mode. Dresselhaus et al have provided an in-depth review of the Raman spectra of... 

Figure 4. Raman spectra of the thymine carbonyl vibrations the three DNA fully deuterium exchanged in D2O. The spectrum (A) is from [d(A5T5)2)2 the spectrum (B) is from Id(TTATTATAATATTATAATAA)J2 and the spectrum (C) is from poly(dA) poly(dT). Spectra are taken at 5° C in 0.5 M NaCl (pH 6.8). The difference spectra arc (D) is spectrum (A) minus spectrum (B) and spectrum (E) is spectrum (A) minus spectrum (C).

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