Solid-State <sup>129</sup>Xe and <sup>131</sup>Xe NMR Study of the Perxenate Anion XeO<sub>6</sub><sup>4-</sup>
Bibliographic record
Abstract
Results of the first solid-state 131Xe NMR study of xenon-containing compounds are presented. The two NMR-active isotopes of xenon, 129Xe (I=1/2) and 131Xe (I=3/2), are exploited to characterize the xenon magnetic shielding and quadrupolar interactions for two sodium perxenate salts, Na4XeO6.xH2O (x=0, 2), at an applied magnetic field strength of 11.75 T. Solid-state 129/131Xe NMR line shapes indicate that the local xenon environment in anhydrous Na4XeO6 adopts octahedral symmetry, but upon hydration, the XeO6(4-) anion becomes noticeably distorted from octahedral symmetry. For stationary, anhydrous samples of Na4XeO6, the heteronuclear 129/131Xe-23Na dipolar interaction is the principal contributor to the breadth of the 129/131Xe NMR lines. For stationary and slow magic-angle-spinning samples of Na4XeO(6).2H2O, the anisotropic xenon shielding interaction dominates the 129Xe NMR line shape, whereas the 131Xe NMR line shape is completely dominated by the nuclear quadrupolar interaction. The xenon shielding tensor is approximately axially symmetric, with a skew of -0.7+/-0.3, an isotropic xenon chemical shift of -725.6+/-1.0 ppm, and a span of 95+/-5 ppm. The 131Xe quadrupolar coupling constant, 10.8+/-0.5 MHz, is large for a nucleus at a site of approximate Oh symmetry, and the quadrupolar asymmetry parameter indicates a lack of axial symmetry. This study demonstrates the extreme sensitivity of the 131Xe nuclear quadrupolar interaction to changes in the local xenon environment.
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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) | 0.002 | 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".