In situ spatially resolved measurements

Donazzi A, Livio D, Maestri M, et al Synergy ofhomogeneous and heterogeneous chemistry probed by in situ spatially resolved measurements of temperature and composition, Angew Chem Int Ed Engl 50 3943—3946, 2011b. 

More recently, a new methodology involving in situ spatially resolved Raman measurements of major gas-phase species concentrations across... 

In this section, we describe time-resolved, local in-situ measurements of chemical potentials /, ( , f) with solid galvanic cells. It seems as if the possibilities of this method have not yet been fully exploited. We note that the spatial resolution of the determination of composition is by far better than that of the chemical potential. The high spatial resolution is achieved by electron microbeam analysis, analytical transmission electron microscopy, and tunneling electron microscopy. Little progress, however, has been made in improving the spatial resolution of the determination of chemical potentials. The conventional application of solid galvanic cells in kinetics is completely analogous to the time-dependent (partial) pressure determination as explained in Section 16.2.2. Spatially resolved measurements are not possible in this way. 

In situ measurements of stratospheric reactive trace gas abundances provide an opportunity to test the fundamental photochemical mechanisms (3). The advantage of such measurements is that they are local, so the simultaneous measurements of trace gases place a true constraint on the possible photochemical mechanisms. These measurements are also able to resolve small-scale spatial and temporal structure in the trace constituent fields. The disadvantage of in situ measurements is that they do not capture the global or perhaps even seasonal view of photochemical transformations because they are seldom done frequently enough or in enough places to provide that information. Another disadvantage of in situ measurements is that they must be made from platforms in the stratosphere, and these remote observational outposts have their liabilities. 

If, however, solid electrolytes remain stable when in direct contact with the reacting solid to be probed, direct in-situ determinations of /r,( ,0 are possible by spatially resolved emf measurements with miniaturized galvanic cells. Obviously, the response time of the sensor must be shorter than the characteristic time of the process to be investigated. Since the probing is confined to the contact area between sensor and sample surface, we cannot determine the component activities in the interior of a sample. This is in contrast to liquid systems where capillaries filled with a liquid electrolyte can be inserted. In order to equilibrate, the contacting sensor always perturbs the system to be measured. The perturbation capacity of a sensor and its individual response time are related to each other. However, the main limitation for the application of high-temperature solid emf sensors is their lack of chemical stability. 

In summary, the establishment of a graded scale loading in combination with spatially resolved stress or strain measurements could be an effective method for an ex-situ investigation of failure mechanisms and fracture-mechanical parameters. 

With LA, MC-ICP-MS isotope ratio measurements can be performed in just a few minutes per sample as compared with the several hours per sample required for TIMS analysis. In addition, LA-MC-ICP-MS can yield spatially resolved isotope ratio characterization. Thus, provenance studies of ceramic paints, glazes, and slips in situ by LA-MC-ICP-MS measurement of lead and/or other isotope ratios are obvious areas for future development. Hints of the potential of this approach are highlighted in a recent study by Huntley [74], which showed that interaction on different spatial scales can be detected via elemental analysis of paste together with lead isotope analysis of glaze paints on Zuni glazed wares. 

From a methodological point of view, of particularly interest have been improvements in the chemical sensitivity of STM and AFM characterization. This is especially desirable for electrochemists, as electrochemical environments prevent the combined characterization by other surface techniques, as are frequently used for composition determinations in vacuum. Tunneling spectroscopy measurements to obtain 7 y and d//dV y relationships may provide a certain degree of information regarding the electronic structure of the substrate surface and adsorbed molecules [77], and the use of ionic liquids of large electrochemical windows is favorable in this respect. One major enhancement would be to complement SPM with other spatial, time- and energy-resolved surface in-situ techniques. For example, a combination of scanning electrochemical microscopy and atomic force microscopy... 

Horn R, Komp O, Geske M, Zavyalova U, Oprea I, Schlogl R Reactor for in situ measurements of spatially resolved kinetic data in heterogeneous catalysis. Rev Sci Instrum 81 064102, 2010. 

The combination of spectrometry with a microscopy enables spatially (locally) resolved measurements, depending on the scale of resolution the method is termed spectromicroscopy. The in situ combination of spectrometry with electrochemistry is called spectro-electrochemistry. Note that while most forms of spectroscopy involve the interaction of electromagnetic radiation with a system, the term is also used at times in a more general sense as in electrochemical impedance spectroscopy. 

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