Spectroelectrochemistry visible spectroscopy

Optical Spectroscopy General principles and overview, 246, 13 absorption and circular dichroism spectroscopy of nucleic acid duplexes and triplexes, 246, 19 circular dichroism, 246, 34 bioinorganic spectroscopy, 246, 71 magnetic circular dichroism, 246, 110 low-temperature spectroscopy, 246, 131 rapid-scanning ultraviolet/visible spectroscopy applied in stopped-flow studies, 246, 168 transient absorption spectroscopy in the study of processes and dynamics in biology, 246, 201 hole burning spectroscopy and physics of proteins, 246, 226 ultraviolet/visible spectroelectrochemistry of redox proteins, 246, 701 diode array detection in liquid chromatography, 246, 749. 

Infrared spectroelectrochemical methods, particularly those based on Fourier transform infrared (FTIR) spectroscopy can provide structural information that UV-visible absorbance techniques do not. FTIR spectroelectrochemistry has thus been fruitful in the characterization of reactions occurring on electrode surfaces. The technique requires very thin cells to overcome solvent absorption problems. 

Figure 12.1 Schematic of the spectroelectrochemistry apparatus at the University of Dlinois. The thin-layer spectroelectrochemical cell (TLE cell) has a 25 p.m thick spacer between the electrode and window to control the electrolyte layer thickness and allow for reproducible refilbng of the gap. The broadband infrared (BBIR) and narrowband visible (NBVIS) pulses used for BB-SFG spectroscopy are generated by a femtosecond laser (see Fig. 12.3). Voltammetric and spectrometric data are acquired simultaneously.

We can deduce the meaning of the word spectroelectrochemistry by dissecting it piece by piece. Spectroelectrochemistry follows an electrochemical process by the use of electromagnetic radiation (hence spectra- ). In principle, any form of spectroscopy can be used to follow the progress of an electrode reaction, but in practice we tend to concentrate on two, namely UV—visible ( UV—vis ) spectroscopy and a form of microwave spectroscopy known as electron paramagnetic resonance (EPR), as described below. 

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... 

Electronic Absorption Spectroelectrochemistry. Electronic absorption spectroscopy with UV and visible light is a form of spectroelectrochemistry typically employed as a transmission experiment to investigate changes in absorbance due to a species being oxidized or reduced. Typically the potential is scanned while the absorbance at a particular wavelength is recorded or the potential is stepped while a full spectrum is collected. Spectroelectrochemistry of this type can be used to establish spectroscopic signatures of reduced or oxidized forms of a compound that can be correlated to excited state transient absorbance spectroscopy. 

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