Dimensionless transient response curves

Figure 26.8 Dimensionless transient response curves of N2 0, N2 0, and Ar obtained following the isotopic switch NO/H2/ 02/Ar/He N0/H2/ 02/Ar/He at 140 °C over...

Figure 3.17(a) shows dimensionless (Z = 1 corresponds to 2 mol% Og) gas-phase transient isothermal response curves of... 

Another approach to TG/SC experiments does not rely on the mediator feedback [56]. The reactant galvanostatically electrogenerated at the tip diffuses to the substrate and undergoes the reaction of interest at its surface. The substrate current is recorded as a function of either time or the tip/ substrate separation distance (approach cnrves). The theory for transient responses, steady-state TG/SC approach curves, and polarization cnrves (i.e., 4 vs. E ) was generated solving the diffnsion problem numerically (an explicit finite difference method was used). The substrate process was treated as a first-order irreversible reaction, and the effects of its rate constant and the experimental parameters were illnstrated by families of the dimensionless working curves (Figure 5.11). 

In Fig. 7.36, the SWV curves of a first-order catalytic mechanism for different values of the dimensionless kinetic constant /sw (= (k + k2)z) at disc electrodes are shown. For jsw > 1.5, a time-independent current is reached whatever the shape and size of the electrode. In order to determine the transient or stationary nature of the SWV current, the forward (y/f) and reverse (i/q) components of the response must be analyzed, since the net current is bell shaped in all the cases. 

The solution of the above problem applies to both transient and steady-state feedback experiments. Since transient SECM measurements are somewhat less accurate and harder to perform, most quantitative studies were carried out under steady-state conditions. The non-steady-state SECM response depends on too many parameters to allow presentation of a complete set of working curves, which would cover all experimental possibilities. The steady-state theory is simpler and often can be expressed in the form of dimensionless working curves or analytical approximations. 

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