Determining Bimolecular Rate Constants for Annihilation Reactions of Electrogenerated Ru(bpy)<sub>3</sub><sup>2+</sup> Radical Ions by Means of Electrochemiluminescence Transients at a Conventional Electrode and an Ultramicroelectrode: Toward Single Events
Bibliographic record
Abstract
This work presents a thorough analytical procedure for measuring ion-annihilation electrochemiluminescence (ECL) reaction kinetics exemplified with Ru(bpy) 3 2+ . Using a 2 mm diameter platinum electrode and a 25 μm diameter platinum ultramicroelectrode (UME), we captured the rapid kinetic profiles of ECL transients during potential-stepping experiments through the use of advanced time-resolved instrumentation. The associated bimolecular annihilation rate constant, k ann, was modeled using two-dimensional (2D) finite element analysis in COMSOL Multiphysics software. The k ann was estimated to be (9 ± 1) × 10 9 M –1 s –1 by fitting simulated ECL transients to experimental data at frequencies of 0.5 Hz, 5 Hz, and higher frequencies. In fact, our 2D model simulating diffusion, reaction, and decay of electroactive species in the vicinity of both conventional macroelectrodes (2 mm) and UMEs has, for the first time, demonstrated effectiveness in extracting crucial chemical information (e.g., reaction mechanisms, intermediate species) and kinetic information (e.g., rate constants, reaction kinetics, mass transport dynamics) from electrochemiluminescence systems. It was discovered that ECL transients at the 25 μm UME represent single events, whereas those at the 2 mm electrode display ensemble ECL kinetic behavior.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".