Dissociative Adsorption and Thermal Evolution of Acetic Acid on Si(100)2×1: Surface-Mediated Formation of Ketene and Acetaldehyde from Unidentate and Bidentate Acetate Adsorbates
Bibliographic record
Abstract
The dissociative adsorption of acetic acid on Si(100)2×1 at room temperature has been investigated by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD), as well as density-functional theory (DFT) calculations. The three C 1s features obtained by XPS measurement can be attributed to the carboxyl C of bidentate acetate (at 286.9 eV) and unidentate acetate (at 289.8 eV), resulting from O−H dissociation upon adsorption, and the methyl C (at 285.7 eV). Furthermore, the formation of bidentate acetate at a low exposure is found to be followed by that of unidentate acetate at a higher exposure, with approximately equal population for both adstructures at the saturation exposure. This is also supported by our DFT calculations, which show that the bidentate acetate adstructure is the most stable configuration among the calculated adstructures. The combined temperature-dependent XPS and TPD studies provide strong evidence for the formation of ketene, acetaldehyde, and CO, with almost half of the adstructures dissociated into methyl groups that become SiC with increasing annealing temperature to 933 K. We propose plausible surface-mediated reaction pathways that could account for these products. The present work indicates the pivotal importance of the 2×1 surface in facilitating the thermally driven formation of ketene and acetaldehyde from the acetate adstructures.
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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 | 0.000 | 0.000 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".