High-Field <sup>17</sup>O MAS NMR Reveals <sup>1</sup><i>J</i>(<sup>17</sup>O-<sup>127</sup>I) with its Sign and the NMR Crystallography of the Scheelite Structures for NaIO<sub>4</sub> and KIO<sub>4</sub>
Bibliographic record
Abstract
High-field, ambient-temperature (AT) 17 O MAS NMR spectra of the tetraoxoanion IO 4 – in NaIO 4 and KIO 4 exhibit unusual line-shape features for the central transition (CT), which so far have not been observed in any second-order broadened line shape for the CT of a quadrupolar nucleus. These features are caused by an unusually large isotropic 1 J ( 17 O- 127 I) spin coupling (∼500 Hz) and appear like “teeth-on-a-saw”. This study reports interesting results obtained from optimized fitting of the spectra using our recently described XSTARS software. The results include determination of a positive sign for 1 J ( 17 O- 127 I) (= +500 Hz), an unusual observation in solid-state NMR. NMR crystallography shows a very precise correlation between extraordinary small changes for the 17 O asymmetry parameter (η Q ) and changes for a tetrahedral O–I–O angle upon distortion from an ideal tetrahedron. Similarly, the spectral analysis shows that the NMR crystallography requires the principal axes V zz ( 17 O) and δ zz ( 17 O) of the PAS for these tensors are both almost along the I–O bond. All the experimental data are in excellent agreement with our ADF and CASTEP calculations.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| 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".