Electron stimulated desorption of H− from thin films of thymine and uracil
Bibliographic record
Abstract
We present measurements of low energy (0–38 eV) electron stimulated desorption of H− from room temperature thin films of pure thymine (T) and uracil (U), condensed on polycrystalline Pt, and describe in detail the experimental methods required for such studies. The nominal film thicknesses are estimated to range from 0.08 to 2.7 monolayers; sublimation of the films at 69 °C (T) and 82 °C (U) onto the room temperature Pt substrate leads to nonuniform film growth, i.e., volumetric clustering, particularly in the submonolayer regime. H− formation by electron impact occurs via dissociative electron attachment (DEA) to the molecules, and results in strong desorption peaks near 8.6 eV for either molecule, whereas above 12–13 eV nonresonant dipolar dissociation dominates the desorption yields. Comparison of the present condensed phase results with gas phase measurements suggests that the desorbing H− produced at the DEA peak are mainly the result of CH bond cleavage, while near the desorption threshold of about 5 eV NH bond cleavage via DEA may also contribute to the H− signal. The present measurements suggest that localized resonances involving DNA bases, leading to the formation of anions and their associated neutral radical moieties, contribute to the resonant signature observed recently in the strand break yields of double stranded DNA irradiated with 3–20 eV electrons.
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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".