Sodium-doping as a reference to study the influence of intracluster chemistry on the fragmentation of weakly-bound clusters upon vacuum ultraviolet photoionization
Bibliographic record
Abstract
The fragmentation of methanol, water, dimethyl ether, and acetic acid clusters upon photoionization with a single vacuum ultraviolet (VUV) photon of 10.1 eV, 13.3 eV, or 17.5 eV energy is studied with mass spectrometry. The sodium-doping method is used as an independent approximate measure of the original cluster size distribution providing information on the degree of fragmentation upon VUV ionization. The experimental results show strong fragmentation for (CH(3))(2)O and CH(3)CO(2)H clusters but minor fragmentation for H(2)O and CH(3)OH clusters. The pronounced cluster decay for (CH(3))(2)O and CH(3)CO(2)H is explained by additional intracluster chain reactions that occur after the initial fast proton transfer in the ionic clusters, i.e. the decay of (CH(3))(2)O molecules into H(2), CO, and CH(4) catalyzed by the methoxymethyl radical, and the decay of CH(3)CO(2)H molecules into CO(2) and CH(4) catalyzed by the acetyloxy radical. The absence of equivalent reaction cycles in ionic H(2)O and CH(3)OH clusters after the fast proton transfer is consistent with the much less pronounced cluster fragmentation observed upon VUV ionization. The study shows that VUV photoionization even at threshold cannot in general be considered a soft ionization method for weakly-bound clusters, largely because of potential intracluster reaction.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".