Acquisition of Wideline Solid-State NMR Spectra of Quadrupolar Nuclei
Bibliographic record
Abstract
Solid-state NMR is increasingly used for the study of quadrupolar nuclei (spin > 1/2) across the periodic table. There are numerous instances where the magnitude of the quadrupolar interaction is so great that the NMR powder patterns span ranges of hundreds of kilohertz to tens of megahertz, well beyond the range of conventional wideline patterns. Such spectra, which we refer to as ultra-wideline (UW) NMR spectra, cannot be acquired using standard high-power, rectangular pulses, since the associated excitation bandwidths are often much smaller than the pattern breadths. However, it is possible to acquire high-quality UW NMR spectra utilizing a combination of frequency-stepped spectral acquisitions, CPMG echo trains, and chirped pulses. The use of probes with large detection bandwidths and high magnetic fields also greatly aid in improving spectral quality. In this article, techniques for the acquisition of UW NMR spectra are discussed, along with hardware considerations and examples of applications of UW NMR to a variety of materials.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.012 | 0.009 |
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".