Potential-modulated UV-visible Reflectance Spectroscopy

The waveform of potential modulation is a sine wave in most of the cases. Using the sine wave, direct correspondence of the results of the potential-modulated spectral measurements to those of the ac impedance measurements can be made straightforwardly, as described in later sections. [Pg.54]

In the case of sine wave modulation, the electrode potential E is described using the complex representation as [Pg.54]

Division of Rac by Eac/ ac and further by the time-averaged reflectance, which is equal to Rdc=h.dc/h, results in an expression [Pg.54]

When the reflection signal has a phase delay in reference to ac but the delay is smaller than njl, the value of is in the range 0° i -re/2. In this case, Im[(AR/R)ER] has a different sign than that of Re[(AR/R)ER] at a given wavelength. [Pg.55]

The spectrum of an ER signal, i.e. the plot of (AR/R)er as a function of k, is called the electroreflectance (ER) spectrum. Electroreflectance measurement can also be carried out during linear potential scan or potential step of Ejc- Under linear potential scan, one obtains the voltammogram of the ER signal, the so-called ER voltammogram. [Pg.55]

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