Visible reflectance spectroscopy

Some of the transition metal macrocycles adsorbed on electrode surfaces are of special Interest because of their high catalytic activity for dloxygen reduction. The Interaction of the adsorbed macrocycles with the substrate and their orientation are of Importance In understanding the factors controlling their catalytic activity. In situ spectroscopic techniques which have been used to examine these electrocatalytlc layers Include visible reflectance spectroscopy surface enhanced and resonant Raman and Mossbauer effect spectroscopy. This paper Is focused principally on the cobalt and Iron phthalocyanlnes on silver and carbon electrode substrates. 

Of special Interest as O2 reduction electrocatalysts are the transition metal macrocycles In the form of layers adsorptlvely attached, chemically bonded or simply physically deposited on an electrode substrate Some of these complexes catalyze the 4-electron reduction of O2 to H2O or 0H while others catalyze principally the 2-electron reduction to the peroxide and/or the peroxide elimination reactions. Various situ spectroscopic techniques have been used to examine the state of these transition metal macrocycle layers on carbon, graphite and metal substrates under various electrochemical conditions. These techniques have Included (a) visible reflectance spectroscopy (b) laser Raman spectroscopy, utilizing surface enhanced Raman scattering and resonant Raman and (c) Mossbauer spectroscopy. This paper will focus on principally the cobalt and Iron phthalocyanlnes and porphyrins. 

Li UPD on highly oriented Au(lll) electrodes has been performed [496] from LiAsFe solutions in PC using quartz crystal microgravimetry, CV, and UV-visible reflectance spectroscopy simultaneously. 

The electrochemistry and cristallography of the nickel oxides have been extensively investigated in connection with the improvement of storage batteries . In-situ UV/visible reflectance spectroscopy and laser raman spectroscopy of the... 

The process of loading zeolites with organometallie complexes always brings to the forefront the question of internal versus external confinement of the metal guest. In this paper we present some experiments based on size exclusion, metal loading and intrazeolite chemistry which in conjunction with FT-FAR-IR, EPR and UV-visible reflectance spectroscopy, critically probe the question of internal versus external location for the case of five representative organometallics,... 

Refs. [i] Holze R (2008) Surface and interface analysis an electrochemists toolbox. Springer, Berlin [ii] Kolb DM (1988) UV-visible reflectance spectroscopy. In Gale Rj (ed) Spectroelectrochemistry. Plenum Press, New York, p 87... 

UV-VISIBLE reflectance spectroscopy is used to investigate the optical properties of metal surfaces and its change with electrode potential, to detect surface states at the metal-electrolyte interface. Differential reflectance spectroscopy gives information on surface reactions or adsorbate formation. 

UV-visible Reflectance Spectroscopy of Thin Organic Films at Electrode Surfaces... 

In this chapter, we are concerned with UV-visible reflectance spectroscopy for an electrode covered with a thin organic film. The UV-visible reflectance spectroscopy is a simple optical measurement What one needs is a sensitive UV-... 

This chapter is devoted to describing the basic aspects of the measurement, instmmentation, measurement techniques, and practical applications of potential-modulated UV-visible spectroscopy as a representative spectroelectrochemi-cal tool to characterize thin organic films on electrode surfaces and to track the kinetics of the electrode surface processes. At the same time, miscellaneous features of the measurement, which may be important for those who intend to apply for the first time the potential-modulated UV-visible spectroscopic method in their experiments, will also be included. However, because of the Hmit to the chapter length as well as the existence of superior review articles on UV-visible reflectance spectroscopy at electrode/solution interfaces [2,6-9], detailed comprehensive description is minimized. With the intention of overviewing the UV-visible spectroscopic method for the benefit of experimental electrochemists, optical issues, especially optical reflection theory, are not detailed. 

The basic optical theory of reflection for a soHd surface covered with a thin film has already been well established. We do not intend to review it here in full detail. Instead, readers can refer to the textbook of optics [12] or review articles on UV-visible reflection spectroscopy at electrode surfaces [2, 6-8]. It must be noted that for some electrode/solution interfaces it is stiU an extremely difficult task to establish the modeling of the interface through the use of classical light reflection theory, as described in the later sections. 

Two examples of the use of UV-visible reflectance spectroscopy at an RDE are of particular significance ... 

In the development of the electrode surface modification method, nano-regulation of the surface films with inorganic nanoclusters and molecular-level tracking of the dynamic phase transition are highlighted. Eor the in-situ characterization of such electrode surfaces covered with a monolayer-level organic film or organic molecule-nanocluster hybrid film, UV-visible reflectance spectroscopy... 

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