On the optimal spectral resolution in quadrupole central transition NMR at ultrahigh magnetic fields
Bibliographic record
Abstract
Quadrupole central transition (QCT) NMR has recently been shown to be an effective way of obtaining high spectral resolution for half-integer quadrupolar nuclei in slowly tumbling molecules in liquids. QCT NMR for slowly tumbling molecules shares many common characteristics with conventional CT-based solid-state NMR for half-integer quadrupolar nuclei. As a result, QCT NMR can be considered to be a cousin of solid-state NMR. Experimental QCT NMR data reported so far in the literature strongly indicate that the optimal resolution achievable in QCT NMR increases with the strength of the applied magnetic field ( B 0 ). In this study, we showed that, if the nuclear quadrupole interaction is the predominant relaxation mechanism, the minimal line width (expressed in ppm) obtained in QCT NMR is proportional to B 0 −3 . In comparison, the corresponding field dependence in CT-based solid-state NMR is only B 0 −2 . We also demonstrated that the presence of shielding anisotropy (SA) would significantly reduce the B 0 −3 dependence in QCT NMR. We presented new 17 O ( I = 5/2) QCT NMR results obtained at multiple magnetic fields up to 35.2 T and carefully examined a wide range of previously reported QCT NMR data from the literature for 27 Al ( I = 5/2), 39 K ( I = 3/2), 45 Sc ( I = 7/2), 59 Co ( I = 7/2), 71 Ga ( I = 3/2), and 87 Rb ( I = 3/2) nuclei. Our findings provide a general guideline for future QCT NMR applications especially at ultrahigh magnetic fields. • Quadrupole central transition (QCT) NMR results obtained at multiple magnetic fields up to 35.2 T. • Line width of QCT NMR signals shows a remarkable B 0 −3 dependence. • QCT NMR data from 17 O ( I = 5/2), 27 Al ( I = 5/2), 39 K ( I = 3/2), 45 Sc ( I = 7/2), 59 Co ( I = 7/2), and 71 Ga ( I = 3/2) nuclei.
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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) | 0.002 | 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 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".