Limitations of the Potential Step Technique to Impedance Measurements Using Discrete Time Fourier Transform
Bibliographic record
Abstract
Recently, a new method of measuring impedance of electrochemical systems was proposed in the literature by Yoo and Park (Yoo, J.-S.; Park, S.-M. Anal. Chem. 2000, 72, 2035). It is based on the analysis of system response to a potential step. Differentiation of the applied potential step and the current response in the time domain followed by applying Fourier transform to both signals allows for determination of the system's impedance. It has been proposed that the measurements carried out in a short time period permit the determination of the system's impedance in the whole frequency range. The aim of the present work was to verify the validity of the impedance spectra obtained using this method, as well as to establish the conditions for which the method may be used. This method was tested using simulated data for a simple ideally polarized electrode and a simple one-electron redox system in the solution. The results show that the reliable impedance spectra may be obtained only for frequencies between 1/(NDeltat) and 1/(2Deltat), where Deltat denotes the sampling time and N is the number of points acquired during the experiment. However, the artifacts are generated when the experimental data are extrapolated to lower frequencies.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.015 | 0.043 |
| Meta-epidemiology (narrow) | 0.001 | 0.002 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.002 | 0.004 |
| Open science | 0.006 | 0.003 |
| Research integrity | 0.003 | 0.004 |
| Insufficient payload (model declined to judge) | 0.003 | 0.003 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".