Warning !

Soas is no longer maintained. You are strongly encouraged to switch to its successor, QSoas

ncai with i = 1 to 9

Eq. (A3) in the appendix of reference [3] is used to fit each peak. This equation makes perfect sense (i.e. is simply derived from the Nernst equation) for one-electron peaks. For two-electron peaks, this is only a phenomenological (i.e. meaningless) equation in which an apparent value for the number of electron accounts for the cooperativity of the electron transfer.

This equation should be used if you believe that peaks have non ideal widths, that can be characterized by an apparent (low) value of napp.

The data are fit to:

$\displaystyle i_{\rm total}=\frac{F^2\nu A\Gamma}{RT} \sum_k \left( n_s^kn_{\rm...
...ight]} {\left( 1+\exp\left[(n_{\rm app}^kF/RT)(E-E^k)\right] \right)^2} \right)$ (2)

Adjusting the coverage $ F^2\nu A\Gamma/RT$ , and for each peak $ k$: one reduction potential ($ E^k$), one value for the stoichiometric number of electrons ($ n_s^k$) and one for the apparent number of electrons ( $ n_{\rm app}^k$). The values of $ n_s^k$ should be fixed during the fit.

You set the initial parameters following the instructions on screen: for each peak, you have to click where you guess its position is and enter the value of $ n_s$ and $ n_{\rm app}$. Only integer values can be set at this stage, a non-integer value can be entered when you edit the initial parameters.



Shape of the signal resulting from a two-electron center, eq. 5 , as a function of the cooperativity of the electron tansfer [7]. $ \Delta E=E_{\rm O/I}-E_{\rm I/R}=$ 200, 100, 50, 0 (dashed line), $ -50$, $ -100$ & $ -500$mV. A negative value of this reduction potential difference means that they are crossed, i.e. the half-reduced intermediate is unstable.

Warning !

Soas is no longer maintained. You are strongly encouraged to switch to its successor, QSoas
Christophe Leger 2009-02-24