Spectroscopic and Electrochemical Windows

Solvent for electrolytes that are to be studied spectroscopically need themselves to be transparent for the light of the wavelengths (for UV and visible light) and wavenumbers (for infrared light and Raman spectroscopy) employed for this purpose. The solvents dealt with here are all colorless when pure but have a UV cut-off that ought to be noted. The functional groups of the solvent molecules have characteristic infrared absorption bands that ought to be avoided when solutes in the solvents are to be studied by infrared or Raman spectroscopy. Table 3.12, mostly adapted from [1], shows the appropriate windows at which the solvents are sufficiently transparent. 

For electrochemical applications, the available window of voltages that can be applied without oxidation and reduction of the solvent itself depends on the working electrode (often the dropping mercury electrode or else a platinum electrode), reference electrode (often the saturated calomel electrode, SCE), and the background electrolyte used to make the solution conductive (often tetraethyl- or -butyl perchlorate), so that a table of values for the various variants used (apart from those often employed) cannot be shown. Water has a rather limited electrochanical window, spanning only -3.5V, compared with -4.5V available for nitromethane and dimethylsulfoxide, -5V available for acetonitrile, and as much as -6V available for propylene carbonate. Some information concerning such electrochemical windows is given in [3]. 

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