Hyperfine and Host−Guest Interactions of the Mu-Cyclohexadienyl Radical in NaY Zeolite
Bibliographic record
Abstract
The adsorption and dynamical behavior of the muonated cyclohexadienyl radical (C 6 H 6 Mu) in NaY zeolite, formed by muonium (Mu) addition on adsorbed benzene, was investigated by the muon spin resonance (μSR) technique, primarily at loadings of 2−3 C 6 H 6 molecules per supercage of NaY. The dynamics of this radical are expected to be the same as its isotopic analogue, C 6 H 7, for which there are no similar data available. Both TF-μSR and ALC-μSR spectra were recorded, with the most detailed information provided by the positions and line widths of the avoided level crossing resonances. In concert with 2 H NMR, neutron diffraction and molecular dynamics studies of the parent benzene molecule, as well as current theoretical calculations, the dominant adsorption site for the C 6 H 6 Mu radical is believed to be the S II Na cation, within a supercage, which gives rise to three observed ALC lines, corresponding to two different orientations for the muon (proton) of the CHMu methylene group: pointing toward (endo) and away (exo) from the Na cation. The cation interaction gives rise to unprecedentedly large (≈20%) shifts in hyperfine coupling constants, indicative of a strong bond formed with the π electrons of the C 6 H 6 Mu radical. An additional but weaker resonance line is also seen, which is interpreted as being due to adsorption at the window sites between supercages. The ALC lines associated with the C 6 H 6 Mu radical bound to both the Na cation and window sites are all broad, ≈1 kG, change little with temperature and exhibit mainly static line shapes over the whole temperature range studied, from 3 to 322 K. This indicates a much stronger host−guest interaction for C 6 H 6 Mu, particularly with the Na cation, than is known for benzene, to the extent that this site acts as an effective trap for the free radical, over the critical μSR time scale of 50 ns.
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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".