ELECTROCHEMICAL METHODS Fundamentals and Applications - Allen.J.Bard

16 P Chapter 1. Introduction and Overview of Electrode Processes
Resultant (/)
• Applied
(E)
Figure 1.2.7 Current
transient (/ vs. t) resulting from
a potential step experiment.
(b) Current Step
When the R s
C d
circuit is charged by a constant current (Figure 1.2.8), then equation 1.2.8
again applies. Since q = Jidt, and / is a constant,
E = iR K
+ 4r\ dt (1.2.11)
or
E = i(R s
+ t/C d
) (1.2.12)
Hence, the potential increases linearly with time for a current step (Figure 1.2.9).
(c) Voltage Ramp (or Potential Sweep)
A voltage ramp or linear potential sweep is a potential that increases linearly with time
starting at some initial value (here assumed to be zero) at a sweep rate и (in V s" 1 ) (see
Figure 1.2.10a).
E = vt (1.2.13)
Constant current source
Figure 1.2.8
circuit.
Current step experiment for an RC