Analysis of the ILIT Response

In this section we will analyze the ILIT response, i.e., just how the open-circuit potential depends upon temperature and upon the properties of the redox couple that is attached to the electrode surface. In Sec. IV.A we will focus on the ILIT response to a perfectly reversible electron-transfer. In Sec. IV.B we will essentially state the kinetic response when the change in the interfacial temperature is described by a step-function. In Secs. C and D we analyze the details of the actual change in the interfacial temperature, the instrument response function, and finally the extraction of the physical parameters from the experimental ILIT response. 

Marcel Dekker, Inc. 270 Madison Avenue, New York, New York 10016 

Response of the Open-Circuit Electrode Potential to a Change in the Interfadal Temperature in the Presence of a Perfectly Reversible Redox Couple Attached to the Electrode Surface 

We have spent some time discussing how to change the interfacial temperature. What do we actually measure We measure the open-circuit potential, thereby passing virtually no external current and circumventing the limitations imposed by solution resistance and/or by the RC time constant produced by the solution resistance in series with the double layer capacitance of the electrode. In this section we will discuss just how the open-circuit potential depends upon the interfacial temperature and upon the interfacial electron-transfer kinetics. 

The open-circuit ILIT response is analogous to the open-circuit response for the coulostatic method [43-45] where the initial perturbation is effected by charge injection. We will confine our analysis to systems where the redox species are attached to the electrode surface. 

---

Our analysis of the ILIT response assumes that the operative rate constant, km [see Eq. (77)], is eflfectively constant during the course of the ILIT measurement. For a perfect step function the operative temperature would be constant at T = T + ATgq [see Eq. (78)]. However, the ILIT perturbation only approximates a step function. Even if the system is only reasonably tuned (see Fig. 5), the postperturbation change in the interfacial temperature will likely be much less than the typical maximum value of ATeq < 5 K. The sensitivity of the rate constant to temperature is deduced from ... 

---