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Heterogeneity Raman spectroscopy

The identification of xanthophylls in vivo is a complex task and should be approached gradually with the increasing complexity of the sample. In the case of the antenna xanthophylls, the simplest sample is the isolated LHCII complex. Even here four xanthophylls are present, each having at least three major absorption transitions, 0-0, 0-1, and 0-2 (Figure 7.4). Heterogeneity in the xanthophyll environment and overlap with the chlorophyll absorption add additional complexity to the identification task. No single spectroscopic method seems suitable to resolve the overlapping spectra. However, the combination of two spectroscopic techniques, low-temperature absorption and resonance Raman spectroscopy, has proved to be fruitful (Ruban et al., 2001 Robert et al., 2004). [Pg.119]

Compared with IR and Raman spectroscopies, ultraviolet-visible (UV-Vis) spectroscopy has had only limited use in heterogeneous catalysis. Nevertheless, this spectroscopy can provide information on concentration changes of organic compounds dissolved in a liquid phase in contact with a solid catalyst, be used to characterize adsorbates on catalytic surfaces, provide information on the... [Pg.16]

Emulsion polymerization is used for 10-15% of global polymer production, including such industrially important polymers as poly(acrylonitrile-butadiene-styrene) (ABS), polystyrene, poly(methyl methacrylate), and poly (vinyl acetate) [196]. These are made from aqueous solutions with high concentrations of suspended solids. The important components have unsaturated carbon-carbon double bonds. Raman spectroscopy is well-suited to address these challenges, though the heterogeneity of the mixture sometimes presents challenges. New sample interfaces, such as WAI and transmission mode, that have shown promise in pharmaceutical suspensions are anticipated to help here also. [Pg.222]

M.M. Reis, P.H.H. Araujo, C. Sayer and R. Giudici, Development of calibration models for estimation of monomer concentration by Raman spectroscopy duiing emulsion polymerization facing the medium heterogeneity, J. Appl. Polym. Sci., 93, 1136-1150 (2004). [Pg.239]

Uniform analyte distribution is often a good assumption for liquid samples such as blood serum or even whole blood if stirring is continuous. For biological tissue, human skin in particular, heterogeneity is a major factor. Detailed morphological structures and molecular constituents of skin have been studied using confocal Raman spectroscopy.9... [Pg.395]

Abstract Within last decade both IR and Raman spectroscopy gained the potential of imaging the chemical heterogeneity of material surfaces. [Pg.15]


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See also in sourсe #XX -- [ Pg.209 , Pg.213 , Pg.222 , Pg.224 ]




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Applications of Raman Spectroscopy to Heterogeneous Catalysis

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