CONFOCAL RAMAN ANALYSIS

With the help of a micro-Raman setup the laser spot can be focused down to about 1 pm in diameter. This allows for the differentiation of single bacterial cells or a biochemical analysis of subcellular components within bacterial (diameter approx. 1 pm) or yeast cells (diameter approx. 5-10pm). A confocal Raman setup achieves an even better spatial resolution [6, 7]. This possibility enables Raman mapping or imaging experiments with spatially resolved information of the whole sample in axial and lateral directions. 

Schuster KC, Urlaub E, Gapes JR (1999) Analysis of single bacterial cells by confocal Raman cpectroscopy, Conference Analysis of Microbial Cells at the Single-Cell Level, Como, Italy... 

The resonance Raman effect was corroborated by confocal Raman mapping of mixtures of M0O3 and M0O2 and of orthorhombic Mo4On. Raman signals were recorded after dilution of the compounds 1 100 in BN, and statistical data analysis was performed (Dieterle et al., 2001, 2002). When the Raman spectrum was excited at 532 nm, (i.e., at a frequency close to the minimum absorption in the UV-vis spectrum) and the integration time was set to 200 s, only the characteristic bands of M0O3 could be detected. Excitation at 632.8 nm produced, albeit at an... 

Balss K, Long F, Veselov V, Akerman E, Papandreou G, Maryanoff C (2008) Multivariate analysis applied to the study of spatial distributions found in drug-eluting stent coatings by confocal Raman microscopy. Anal Chem 80 4853 859. 

The use of a fibre-coupled confocal Raman microscope and an infrared microscope for both point mapping and global imaging in the study of spatial variations in polymer chemistry and morphology is illustrated by studies of the curing of the UV-cured acrylate coatings, crystallinity in drawn polyethylene terephthalate (PET) film, molecular orientation in PET bottles, and the analysis of a PES/PEES copolymer blended with epoxy resin and cured at elevated temperature. 8 refs. 

CLEARCOAT ANALYSIS IN ISOLATED AND MULTI-LAYER PAINT SYSTEMS BY CONFOCAL RAMAN MICROSCOPY... 

The interaction between zinc oxide and stearic acid in a medium suitable to simulate a vulcanized system has been investigated [65] experimentally using vibrational spectroscopic technique. Confocal Raman micro spectroscopy revealed that at ambient temperature both components are phase-separated in the form of microcrystals. When the reaction temperature (SO C and above) is reached only zinc oxide is present in the form of particles while the stearic acid melts and gets molecularly dispersed within the rahher matrix. The analysis points to a core-shell structure of the reacting system stearic acid diffuses to the surface of zinc oxide domains causing the shrinkage of the zinc oxide core and the formation of a shell of increasing thickness made of zinc stearate. 

Chemical imaging is described, including confocal Raman imaging. UV and visible spectroscopy includes innovations such as flow-through sample holders and fiber-optic probes, as well as instruments for analysis of submicroliter volumes and nondestructive analysis for nucleic acid and protein determinations. UV absorption spectral interpretation for organic molecules is covered in depth. Applications described include nucleic acid and protein measurements, spectrophotometric titrations, and new applications in forensic chemistry. Nephelometry, turbidimetry, fluorescence, and phosphorescence are described in detail, including instrumentation and applications. The measurement of color using the CIE system is described with examples. 

Figure 6.10 Scanning electron microscopy and confocal Raman images of a ternary blend— polystyrene (PS), pentafluorostyrene)-b-polystyrene (P5FS-b-PS), and polystyrene-b-poly[poly(ethylene glycol) methyl ether methacrylate] (PS-b-PPEGMA). Solvent casting under 70% relative humidity induces regular pores in which the copolymer distribution depends on the polarity of the component. Red color indicates the presence of PS and P5FS-b-PS, and blue color is indicative of PS-b-PPEGMA. Depth analysis of the pore composition evidenced a heterogeneous distribution of the block copolymer within the pore.

The analysis of MDA-MB-231 cells incubated with 53 was also carried out on a synchrotron-based multiple beam FT-IR imaging (IRENI) set up at the Synchrotron Radiation Center, Stroughton, Wisconsin, equipped with a FPA detector of 96 X 96 pixels, where each pixel corresponds to a 0.54 x 0.54 pm area of the sample. With the better resolution afforded by this technique, the complex appears heterogeneously distributed in the cell, but with a higher perinuclear concentration [79]. In addition, 53 was mapped in cell by SR-UV-SM (synchrotron radiation UV spectromicroscopy), confocal Raman microscopy, and AFM-IR (see Sections 11.3.3 and 11.3.4). Thus, this innovative family of complexes appeared to be a valuable multimodal (and not only bimodal) tool for cell imaging. 

The future of Raman microspectroscopy is probably imaging and optical near-field nano-Raman spectroscopy [529], cfr. Chp. 5.5.2. While conventional laser Raman spectroscopy samples 10 g (mm ), /zRS handles 10 g (nm ) and near-field Raman spectroscopy 10 g (nm ). Mobile Raman microscopy (MRM) allows in situ Raman analysis [530]. One can expect further developments in the field of NIR multichannel Raman spectroscopy with the advent of 2D array detectors offering extended response in the NIR. With these 2D sensors it wiU become possible to apply in the NIR region the powerful techniques already developed in the visible, such as confocal line imaging techniques or multisite remote analysis with optical fibres. 

Ma, J.E., Ji, Z., Zhou, X., Zhang, Z.H., and Xu, E. (2013) Transmission electron microscopy, fluorescence microscopy, and confocal Raman microscopic analysis of ultrastructural and compositional heterogeneity of Comas alba L. Wood cell wall. Microsc. Microanal., 19 (1), 243-253. 

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