Low‐temperature Raman spectra of polycrystalline NH<sub>4</sub>F and ND<sub>4</sub>F
Bibliographic record
Abstract
Abstract Raman spectra of polycrystalline ammonium fluoride and fully deuterated ammonium fluoride were recorded at various temperatures between 80 and 300 K. The spectra were obtained using a cold stage attached to a Raman microscope. At low temperatures the Raman lines were sharper and shifted to higher wavenumbers compared with their room temperature counterparts. However, no indications of any crystalline phase change were observed at low temperatures. A strong line at 2876 cm−1 was assigned to the infrared inactive symmetric NH stretching mode ν1(A1). A very strong line at lower wavenumbers (2818 cm−1) was assigned to the antisymmetric stretching mode ν3(F2). Observed deuterium isotope shifts were in agreement with those calculated using the Redlich–Teller isotope product rule. The degenerate bending modes ν2(E) and ν4(F2) were observed in the Raman spectra of NH4F and ND4F for the first time. The ν2 fundamental was split into doublets in the low‐temperature spectra, as predicted from a factor group analysis based on the known crystal structure. Three bands due to translational lattice modes were observed between 400 and 200 cm−1 in the spectra of both isotopic molecules. Several bands in both spectra are assigned to overtones and combinations involving an ammonium ion libration, but no bands directly attributable to ammonium ion librations were observed. Copyright © 2001 John Wiley & Sons, Ltd.
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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".