In situ spectroscopic characterization

Castagnola, M.J., Neylon, M.K. and Marshall, C.L. (2004) Coated bifunctional catalysts for NOx SCR with C3H6 Part II. In situ spectroscopic characterization, Catal. Today, 96, 61. 

Girlando A, Sissa C, Terenziani F, Painelli A, Chwialkowska A, Ashwell GJ (2007) In situ spectroscopic characterization of rectifying molecular monolayers self-assembled on gold. Chem Phys Chem 8 2195-2201... 

D. Durst, J.R. Mays, J.L. Ruth, B.R. Williams and R.V. Duevel, Micro-scale synthesis and in-situ spectroscopic characterization of some chemical weapons related organophosphonate compounds, Anal. Lett., 31, 1429-1444 (1998). 

Mascioni M, Sands JM, Palmese GR. (2003) Real time in situ spectroscopic characterization of radiation induced cationic polymerization of glycidyl ethers. Nucl Instr and Meth in Phys Res B 208 353-357. 

After a short introduction to tunneling in Sec. 2, special attention is given in Sec. 3 to operating conditions on semiconductors because these are not as trivial as for metals and may raise experimental problems. Questions related to in-situ spectroscopic characterization are addressed in the following section. Section 5 reviews in-situ as well as ex-situ studies (in UHV or in air after treatment of the surface in solution) according to the materials and electrochemical reactions involved. Silicon electrodes are treated separately, mostly in relation to electrochemical etching and por-pous layer formation. The two final sections outline perspectives and draw general conclusions. Details related to instrumentation and tip preparation are not discussed here unless they are specific to semiconductors. They are reviewed in [9]. Experimental aspects of in-situ AFM are not presented either, because the immersion of the surface in an electrolyte raises no specific problem. The theory and other applications of AFM are discussed elsewhere [3, 4]. 

After assessing the issues in the research, we propose several directions for future research. First, it is important to find the correlation between structure/composition of the catalyst and catalytic performance. More careful studies are needed in the future. Second, it is worthwhile to study the nature of active sites and reaction mechanisms on some of new catalysts. This can be done by in situ spectroscopic characterization of working catalysts, by conducting kinetic studies, and by isotopic... 

In addition to characterization of intermediates, in situ spectroscopic techniques can be applied in kinetic studies, providing additional mechanistic insight. Also, isotopic labeling studies have proven very useful, especially vhen studying the individual steps of a catalytic cycle [5, 6]... 

For their characterization, electrochromic compounds are initially tested at a single working electrode under potentiostatic control using a three-electrode arrangement. Traditional characterization techniques such as cyclic voltammetry, coulometry, chronoamperometry, all with in situ spectroscopic measurements, are applied to monitor important properties [27]. From these results, promising candidates are selected and then incorporated into the respective device. 

A number of modern physical techniques are used to characterize heterogeneous catalysts. These methods range from techniques probing the interaction of catalysts with probe molecules, to in situ surface characterization techniques as well as structural elucidation under both in situ and ex situ conditions. In general, interaction of catalysts with probe molecules is followed using some spectroscopic property of the probe molecule itself and/or the changes induced by the heterogeneous catalyst. The spectroscopic techniques used include vibrational spectroscopies, NMR spectroscopy, UV-Vis spectroscopy and mass spectrometry to name a few examples. Similarly, in situ techniques tend to use properties of probe molecules but also combined with structural techniques such as X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). In recent years XAS has been widely used in the characterization of catalysts and catalyst surfaces. 

This section describes various strategies for the immobilization of macrocycles on electrode surfaces and their characterization by both electrochemical and in situ spectroscopic techniques in solutions devoid of dioxygen. It also provides theoretical foundations involved in the analysis of the mechanisms of oxygen reduction at such interfaces based on measurements performed under forced convection. Studies involving a number of carefully selected phthalocyanines, and porphyrins, will be presented and discussed, which in our view best illustrate the nuances of the rich behavior this class of adsorbed electrocatalysts can exhibit. These examples serve to... 

The use of infrared spectroscopy in the Earth and environmental sciences has been widespread for decades however, until development of the attenuated total reflectance (ATR) technique, the primary use was ex situ material characterization (Chen and Gardella, 1998 Tejedor-Tejedor et al., 1998 Degenhardt and McQuillan, 1999 Peak et al., 1999 Wijnja and Schulthess, 1999 Aral and Sparks, 2001 Kirwan et al., 2003). For the study of environmental systems, the strength of the ATR-Fourier transform infrared (FTIR) technique lies in its intrinsic surface sensitivity. Spectra are collected only from absorptions of an evanescent wave with a maximum penetration depth of several micrometers from the internal reflection element into the solution phase (Harrick, 1967). This short optical path length allows one to overcome any absorption due to an aqueous phase associated with the sample while maintaining a high sensitivity to species at the mineral-water interface (McQuillan, 2001). Therefore, ATR—FTIR represents a technique capable of performing in situ spectroscopic studies in real time. 

Some of them have been shown to exist only in solution by in situ spectroscopic measurements or by indirect methods, and very few have been structurally characterized [3, 22-37]. 

Study the kineties of fuel cell electrode reactions on well-characterized model eleetrodes and high surface area fuel eell electrocatalysts using modem eleetroanalytieal methods. Study the meehanisms of the reactions using state-of-the art in-situ spectroscopes. 

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