Microspectroscopic techniques

Roberts, D.R., Scheinost, A.C., and Sparks, D.L., Zinc speciation in a smelter-contaminated soil profile using bulk and microspectroscopic techniques, Environ. Sci. Technol., 36, 1742, 2002. 

A collimated beam of light spectrally dispersed by a diffraction grating or a quartz prism yields a spectrum which can be used as a series of wavebands of near-monochromatic radiation. The intensities of different regions of the dispersed spectrum depend on the spectral distribution of the source. The dispersed spectrum is focused only on a few centimeters of the sample surface, and exposure is carried out for a constant duration. A microspectroscopic technique is generally used to study changes in absorbance properties of the sample subsequent to exposure. 

Infrared imaging using FTIR microspectroscopic techniques has emerged as an effective approach for studying complex or heterogeneous specimens [7]. The technique can be used to produce a two- or three-dimensional picture of the properties of a sample. This is achievable because, instead of reading the signal of... 

Microspectroscopic techniques provide alternative means for the characterisation of laminates. In situ )uTMA analysis has been used for the identification of all layers of a multilayer packaging material on the basis of the softening temperatures [481,483]. 

Carter et al. [402] have addressed the chemical assessment of automotive clearcoats (usually melamine-cross-linked systems), which requires evaluation of the cross-linker type, HALS and UV absorbers. Coating systems require a variety of chemical analytical techniques for their evaluation [403], including UV microspectroscopy [402, 404], /xFTIR [402,405], /xRS [406,407], NMR [408], ESR [409], ToF-SIMS [410,411] and hydroperoxide titration [412]. Ideally, what is needed for industrial evaluation purposes is a set of techniques that can follow chemical changes in individual layers of a full automotive paint system, typically consisting of 45 /xm clearcoat, 25 /xm basecoat, 35 /xm primer, and 35 /xm E-coat on metal. The clearcoat must shield underlayers from UV. Unlike the case for IR radiation, examination of 30 /xm and thinner clearcoat layers with 0.3 to 0.4 /xm radiation lends itself quite well to the use of microscopes and microspectroscopic techniques. UV microspectroscopy of 10 /xm paint system cross-sections is the method of choice cfr. also Chp. 1.1). UV microspectroscopy... 

Vibrational microspectroscopic techniques turned out as a promising tool for breeding control, offering the opportunity of nondestructive analysis of plant material. 

Microspectroscopic techniques provide the opportunity to analyze infected material spatially resolved. Applying FT-IR microspectroscopy, mycelia of two fungal species were successfully discriminated within beech wood sections and chemical differences of the mycelia grown on top and within vessels of the wood blocks were revealed (Figure 6.30) [182]. 

Infrared and Raman instrumental advances, microspectroscopic techniques and fibre optics and new sampling methods have made possible many biological and medical applications. Correction for background and interference is automatically performed by most modern instruments. The use of statistical techniques and of derivative spectra for the examination of subtle differences in cases where bands overlap have been very useful. The direct examination of cells and tissues by infrared " can provide useful information on cellular composition, packing of cellular components, cell structure, metabolic processes and disease. Near infrared and Fourier Transform techniques may be applied to the study of food. ... 

Lasch, P. and Naumann, D. (1998) FT-IR microspectroscopic imaging of human carcinoma in thin sections based on pattern recognition techniques. Cell. Mol. Biol. 44(1), 189-202. 

Microspectroscopy. In situ spectroscopic methods are essential to a fundamental understanding of catalytic reactions, thanks to their ability to unravel useful structure-function relationships. However, most of these techniques average information over the whole catalyst sample, whereas in many cases it is of utmost importance to probe distinct areas of catalyst particles or grains to reveal how the structural features render into catalytic function. For this purpose, microscopic methods may be of assistance. The following section lists the examples of application of in situ microspectroscopic methods in catalysis. 

Another important criterion for Raman microspectroscopic analysis is the selection of the areas to be analyzed, as this offers the possibility to directly correlate the spectroscopically determined outcomes with results from other techniques such as histology/histomorphometry [200]. In addition, most of the samples from clinical or animal studies are in most cases labeled with... 

Recently, Raman microspectroscopic analysis has been the analytical tool of choice to determine human bone compositional and structural changes in health and disease, as a function of aging, and in response to various therapies, due to its superb spatial resolution and its combination with other techniques such as nanoindentation, quantitative backscattered electron imaging, FT-IR, and histol-ogy/histomorphometry [163,171,186,188, 201, 202, 262, 274, 277-281]. 

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