Linear polarization technique description

This is a well established technique applied to determine the corrosion rate of steel in concrete. A full theoretical description of this technique is given in Chapter 3. The specimen is polarized to within 25 mV of the corrosion potential (Ecorr) as the dependence of current with potential in the vicinity of corrosion potential is linear. The open circuit potential (E oii) of the reinforcement is measured against a reference electrode. Starting from this potential, the steel reinforcement is polarized to 25 mV from Ecorr at a sweep rate of 5-lOmV/min and a plot of A vs At is constructed. The polarization resistance relates the slope of the polarization curve in the vicinity of corrosion potential to the corrosion current. This technique is based on the Stern Geary equation described in Chapter 3, and given below ... 

Abstract In the first part of this chapter we will illustrate circular dichroism and we will discuss the optical activity of chemical compounds with respect to light absorption which is at the basis of this technique. Moreover, we will introduce the phenomena that lie behind the technique of optical rotatory dispersion. We thought appropriate to include a brief description of linear dichroism spectroscopy, although this technique has nothing to do with optical activity. In the final part of the chapter we will introduce the basic principles of the luminescence teehniques based on polarized (either circularly or linearly) excitation. The experimental approach to the determination of steady-state and time resolved fluorescence anisotropy will be illustrated. For all the teehniques examined in this chapter the required instrumentation will be schematieally deseribed. A few examples of application of these techniques to molecular and supramolecular systems will also be presented. 

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