Fourier transform faradaic admittance measurements II. Ultra-rapid, high precision acquisition of the frequency response profile
✍ Scribed by Sam C. Creason; Donald E. Smith
- Publisher
- Elsevier Science
- Year
- 1972
- Weight
- 256 KB
- Volume
- 40
- Category
- Article
- ISSN
- 0022-0728
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✦ Synopsis
Recent publications have demonstrated and discussed the use of Fourier analysis to characterize the faradaic admittance frequency response profile using impulse 1-3, random white noise 4 and pseudorandom white noise 4 test signals. In each ease it was shown that frequency domain data can be a~uired with precision and rapidity which surpasses that normally associated with classical measurements using sinusoidal test signals. If an on-line computer is available, the extent of signal averaging required to obtain the desired level of data precision is the rate-limiting step for data acquisition with all reported variations of Fourier transform faradaic admittance measurements. Reports to date suggest that the complex periodic waveform referred to as pseudo-random white noise is superior to broadband signals such as the impulse and random white noise as far as minimizing signal averaging requirements is concerned 4-6. The basis for this advantage is discussed in the literature 4-6 and its implications for electrochemistry will be explored in further detail elsewhere 7 . While significant, the advantages observed through the use of pseudorandom white noise 4 in faradai¢ admittance measurements were not as great as expected on the basis of corresponding comparisons using dummy cells comprised of linear components (precision resistors and capacitors) a,8 . Because smaller test signal amplitudes were utilized for the faradaic admittance measurements, it was originally concluded that extraneous noise was responsible for this situation 4 . However, we have recently found that a major source of data scatter in faradaie admittance measurements with conventional pseudo-random white noise arises from contributions of faradaie nonlinearity a . Recognition of this fact has led to the development in our laboratories of a hybrid test signal waveform which appears to be closer to the optimum for Fourier transform faradaie admittance measurements than pseudorandom noise or any other waveform suggested to date. Its use has enabled substantial