Electron-Stimulated Desorption of H<sup>-</sup> from Condensed-Phase Deoxyribose Analogues: Dissociative Electron Attachment versus Resonance Decay into Dipolar Dissociation
Bibliographic record
Abstract
We report the 5−40 eV electron-stimulated desorption (ESD) yields of H - from thin films of the DNA backbone sugarlike analogues tetrahydrofuran ( I ), 3-hydroxytetrahydrofuran ( II ), and α-tetrahydrofurfuryl alcohol ( III ), as well as ESD yields from submonolayer amounts of these compounds condensed on multilayer Ar films. For the pure disordered solid films, our results corroborate the previous observation of a peak in the H - yield function at an incident electron energy, E i, of ∼10 eV attributed to dissociative electron attachment (DEA) along the CH bonds via the formation of a core-excited resonance. For II and III, a second low-energy peak is also observed in the H - ESD yield function. This peak appears near an E i of 7.3 eV as a weak shoulder superimposed on the low-energy side of the 10 eV structure; it is associated with a core-excited Feshbach resonance leading to H - production via DEA to the OH substituent. For each of the three molecules, we observe near 23 eV a third broad peak in the H - ESD yield functions. Measurements of the H - yields, as a function of the coverage of thin Ar spacer films by I, II, and III, suggest that the 23-eV peak is not due to multiple electron scattering, but results from direct transient anion formation above the dipolar dissociation threshold. These results, combined with those recorded at higher Ar spacer thickness, indicate that the 23-eV peak arises principally from decay of a transient anion (or anions) into an electronic excited state (or states), which dissociates into H - and the corresponding positive ion radical.
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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".