Warning !

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lo2i and lr2i, with i = 0 to 2

To fit the log tranforms of oxidative or reductive two-electron waves adjusting 0, 1 or 2 values of k2/k0. The equations used are described and explained in ref. [11,12]. You should first remove a polynomial baseline from the catalytic wave, Dirk's method, and then take the log transform using the logt command. The current equations are:

$\displaystyle \frac{i_{\rm lim}-i}{i}=$ $\displaystyle \exp\left[f(E-E_{\rm I/R})\right] +\exp\left[f(E-E_{\rm I/R})\right] \exp\left[f(E-E_{\rm O/I})\right]$    
  $\displaystyle +{\left(\frac{k_2}{k_0^{\rm I/R}}\right)}^{\rm app} \exp\left[\frac f2(E-E_{\rm I/R})\right] \left( 1+\exp\left[f(E-E_{\rm O/I})\right]\right)$    
  $\displaystyle +{\left(\frac{k_2}{k_0^{\rm O/I}} \right)}^{\rm app} \exp\left[\frac f2(E-E_{\rm O/I})\right]$ (6)

for a reductive wave (lr20, lr21, and lr22) and

$\displaystyle \frac{i_{\rm lim}-i}{i}=$ $\displaystyle \exp\left[f(E_{\rm O/I}-E)\right] \left( 1+ \exp\left[f(E_{\rm I/R}-E)\right] \right)$    
  $\displaystyle +{\left(\frac{k_{-2}^{\rm O}}{k_0^{\rm O/I}}\right)}^{\rm app} \e...
...frac f2(E_{\rm O/I}-E)\right] \left( 1+\exp\left[f(E_{\rm I/R}-E)\right]\right)$    
  $\displaystyle +{\left(\frac{k_{-2}^{\rm O}}{k_0^{\rm I/R}} \right)}^{\rm app} \exp\left[\frac f2(E_{\rm I/R}-E)\right]$ (7)

for an oxidative wave (lo20, lo21, and lo22).

Use lo20 or lr20 if you believe that electron transfer is so fast with respect to turnover that the wave is reversible (from an electrochemistry point of view). (This corresponds to fixing both apparent k2/k0 values to zero.)

Use lo21 or lr21 if this is not the case, but if you want to assume that both apparent k2/k0 have the same value.

Note that measuring the maximal slopes of the log-transforms should help you deciding whether electron transfer is fast or not [12].

If you use lo22 or lr22, both apparent k2/k0 values are adjusted.

Warning !

Soas is no longer maintained.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