NO−C<sub>2</sub>H<sub>4</sub> Reactions on the Surface of Stepped Pt(332)
Bibliographic record
Abstract
NO−C 2 H 4 interactions on the surface of stepped Pt(332) have been studied using Fourier transform infrared reflection−absorption spectroscopy (FTIR-RAS) and thermal desorption spectroscopy (TDS). IR data show that pre-dosed C 2 H 4 molecules suppress the adsorption of NO on the surface of Pt(332) to an extent depending on both C 2 H 4 coverage and the temperatures to which C 2 H 4 pre-adlayers are annealed. At 90 K, the adsorption of NO on step sites is significantly suppressed by C 2 H 4 following exposures greater than 0.32 L. This site-blocking effect persists and is even enhanced when annealing C 2 H 4 pre-adlayers to 200 K, a temperature at which the adsorbed C 2 H 4 molecules are not dissociated. As annealing temperatures are increased beyond 260 K, an ethylidyne species forms and is located on terraces. Consequently, the adsorption of NO on step sites is restored but to an extent smaller than that on a clean Pt(332) surface. The IR spectra also indicate that there are no detectable intermediates resulting from direct chemical reactions between NO and C 2 H 4 /C 2 H 4 -derived hydrocarbons, which can promote N 2 production. The co-adsorption of C 2 H 4 - and C 2 H 4 -derived hydrocarbons does significantly promote N 2 desorption, being dependent on the temperatures to which pre-dosed C 2 H 4 adlayers are annealed. Annealing C 2 H 4 adlayers to temperatures ≤300 K significantly enhances N 2 desorption at temperatures below 400 K, giving rise to a peak at about 340−380 K. This low-temperature N 2 desorption disappears completely after annealing the C 2 H 4 adlayers to >350 K. N 2 desorption at ∼460 K appears to be slightly enhanced. NO dissociation is the rate-limiting step in the reduction of NO by C 2 H 4 - and C 2 H 4 -derived hydrocarbons. The contribution of C 2 H 4 - and C 2 H 4 -derived hydrocarbons to N 2 desorption is mainly attributed to 1) weakening of N−O bonds through an electron-donation effect; and 2) providing a source of reductants, i.e., H, CH x, C 2 H x, and even C, which react with the atomic O from NO dissociation, leaving the surface with more vacant sites for further NO dissociation. The generation of CH x and C 2 H x therefore plays a central role in the NO reduction mechanism.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".