Raman spectral mapping

Figure 2.7 (a) Tip-enhanced near-field Raman spectral mapping ofthe adenine nanocrystal at 30 nm intervals, (b) Raman intensity distribution of two major bands at 739 cm and 1328cm. ... 

I. Blakey, and G.A. George, Raman spectral mapping of photo/oxidised polypropylene, Polym. Degrad. Stab. 2000, 70, 269-275. 

Kazanci, M. et al (2006) Bone osteonal tissues by Raman spectral mapping orientation-composition. / Struct Biol, 156 (3), 489 -496. 

Kozielski, M. et al. (2011) Determination of composition and structure of spongy bone tissue in human head of femur by Raman spectral mapping. J. Mater. Sci. Mater. Med., 22 (7), 1653-1661. 

To elucidate the contribution of the different histological structures to the average Raman spectral signatures from intact pollen grains, we conducted spatially resolved measurements on sections of rye pollen grains. Such mapping experiments can help separation of predominant spectral contributions from different substructures. 

The additional advantage of CARS-CS over DLS and FCS is the spectral selectivity for individual chemical components in their native state, where fluorescent labeling is not desired. This may not only allow mapping of 3D diffusion coefficients, for example inside life cells, but also offer a method to monitor the specific interaction of individual components within complex systems, e.g., aggregation processes of different chemical species. Another prospect is the implementation of CARS cross-correlation spectroscopy that may allow the investigation of correlated fluctuations between two different species. These could be two distinct Raman spectral features of one and the same compound, or a specific intrinsic Raman band and an emission of a more sensitive fluorescence label [160]. 

In order to facilitate the discussion on Raman and IR spectra and spectral maps of human cells, we present here some characteristic spectral features of typical human cells. Although, depending on the cell type and special conditions, these spectra may vary to some extent, the information presented here is aimed at providing the reader with a survey of typical cellular spectral features. 

Fig. 10.18 Spectral mapping of the near-field Raman spectra. The laser power is 0.5 mW at the sample, and the exposure time is 5 s. (Reprinted with permission from Ref. [137].)...

An early application of a pattern recognition method to the prediction of olfactory qualities from physicochemical data was reported by Schiffman C2623. A set of 39 odorants was represented by 25 parameters (including Raman spectral information). Non-linear mapping revealed correlations of the chemical structure and smell. 

A Raman microscope (Renishaw, 785-nm laser, spectral range 800-100cm ) with a line-mapping detector (21 pixels/line) was used to analyze a solid dosage form. The image size was 105 x 88 pixels, that is, 325 pm x 270 pm, and acquisition time was about 40 min. Spectra were smoothed and normalized. Peak heights were determined for the three main compounds—API, lactose, and cellulose (Figure 11)—in order to create distribution maps. 

Thus Raman imaging is a useful tool for detecting small API particles on the surface of pharmaceutical solid forms. It may even be the most suitable chemical imaging technique for API mapping due to its low spatial resolution (up to 0.5 pm/ pixel) and the polymorphism of the spectral information. 

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