Spatially resolved spectroscopy

The elimination of the need to use paramagnetic doping of the catalyst will facilitate future spectroscopic studies both in a catalyst bed and in single catalyst pellets. For spatially resolved spectroscopy, it could also be advantageous to use magnetic nuclei with a wider spread of chemical shifts as compared with H. Extension to other classes of reactors and reactions is feasible and will be addressed. 

The use of magnetic resonance imaging (MRI) to study flow patterns in reactors as well as to perform spatially resolved spectroscopy is reviewed by Lynn Gladden, Michael Mantle, and Andrew Sederman (University of Cambridge). This method allows even unsteady-state processes to be studied because of the rapid data acquisition pulse sequence methods that can now be used. In addition, MRI can be used to study systems with short nuclear spin relaxation times—e.g., to study coke distribution in catalytic reactors. 

So far, two examples of natural abundance 13C imaging have been reported. The first was an extension of the work of Yuen et al.31 which had provided a clear demonstration of the heterogeneity in conversion within a fixed bed. As mentioned previously, this early study had only been successful because the reaction mixture was associated with a relatively simple H NMR spectrum the spectrum gave only 4 spectral peaks with the chemical shift of one being a direct measure of the interparticle liquid composition and hence extent of conversion. Akpa et al.29 extended that work by using 13C spatially-resolved spectroscopy to follow a reaction in which... 

Evolution of NIR Imaging Instrumentation 8.3.1 Spatially resolved spectroscopy - mapping... 

Spatially resolved spectroscopy is used to measure the emission from plasma at its different positions, because the appearance and spectral characteristics of the plasma are quite different depending on the target species as well as the position (Xu et al. 1997). 

Spatially resolved spectroscopy of lo s Pele plume and SO2 atmosphere. Icarus 146, 476-493. 

Fig. 9.1.10 [Akol] Spatially resolved spectroscopy by the ISIS method. The signal from the selected volume element is obtained by the combination of eight signals, a — b — c — d + e + f + g — h.

SPACE a method of spatially resolved spectroscopy, not an acronym... 

The separation of absorption and scattering often requires specific types of instrumentation, based on the theoretical approach that is used. In this section, four main designs will be discussed integrating sphere-based reflectance and transmittance, spatially resolved spectroscopy, time-resolved spectroscopy, and frequency domain photon migration. 

Spatially resolved spectroscopy consists in measuring the light reflected at different distances from the incident light. Typical designs use a set of aligned optical fibers, with one fiber being the source and others the detection systems. Setups based on hyperspectral imaging have... 

While these instrument designs may appear most suitable for laboratory analysis, some manufacturers have proposed apparatus suitable for real-time online process monitoring. It is the case for spatially resolved spectroscopy. A very good review on the topic on pharmaceutical applications to the separation of absorption and scattering was written by Shi and Anderson [34]. A comprehensive review of those techniques and applications in tissue optics can be found in a review by Wilson [35]. 

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