Degradation of functionalized alkanethiolate monolayers by 0–18 eV electrons
Bibliographic record
Abstract
Electron stimulated desorption of neutral molecular fragments is used to study degradation of ordered organic thin films under low-energy (0–18 eV) electron impact, and total electron doses ranging between 180–550 μC/cm2. Different saturated linear thiols HS(CH2)nX (n=2 or 15, and X=CH3 or COOH) are adsorbed from solution onto a gold surface to produce a self-assembled monolayer (SAM). Here, we present yield function measurements for electron stimulated desorption of moities such as H2, CH3, CH3CH2, CH3CH2CH2, CO, and CO2 from such thin chemisorbed films. For CH3-terminated SAMs, neutral fragment desorption thresholds lie between 5–7 eV, whereas for COOH-terminated SAMs, desorption thresholds as low as 0.2 and 3–5 eV are observed. The results suggest that the incident electrons interact with functional groups localized at the film–vacuum interface, which then leads to predominantly methyl group C–H, and C–COOH bond cleavage. In addition to nonresonant degradation mechanisms, which vary monotonically from threshold with increasing incident electron energy, structures in the neutral fragment desorption yield functions are related to resonant electron attachment. Particularly for Au–S(CH2)15COOH monolayers, this mechanism leads to a desorption peak of CO fragments at incident electron energies near 1.0 eV.
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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".