Phase Transitions of Alkanethiol Self-Assembled Monolayers at an Electrified Gold Surface
Bibliographic record
Abstract
We report an in situ vibrational study of the reductive desorption and the oxidative adsorption of an alkanethiol monolayer on Au(111) in an alkaline solution between 5 and 37 °C. Cyclic voltammograms show that the reduction of a hexadecanethiol monolayer gives rise to two current peaks at low temperature. These two peaks slowly merge into a single peak as the temperature increases. The oxidative chemisorption displays a similar behavior. Three oxidative current peaks are observed at low temperature and only one at higher temperature. In situ vibrational spectroscopy shows that these electrochemical changes are related to a sharp phase transition. A sudden increase of the wavenumber of the methylene asymmetric CH stretching d - band from 2918 cm -1 below 12 °C to 2927 cm -1 above 12 °C indicates an abrupt disordering of the monolayer. A sharp transition at the same temperature of 12 °C is observed for the intensity of the differential reflectance CH stretching bands. This shows that changes in orientation of the alkane chains occur simultaneously with the disordering of the monolayer. We suggest that the phase transition from an ordered phase to a disordered phase is related to a sudden increase of ion permeation into the hexadecanethiol monolayer above 12 °C.
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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 | 0.000 | 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) | 0.001 | 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".