Direct observation of a highly forbidden optical transition in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>Sm</mml:mi><mml:mo>:</mml:mo><mml:mi>SrF</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math>
Bibliographic record
Abstract
The $4{f}^{6}\phantom{\rule{0.28em}{0ex}}{}^{7}{F}_{0}\ensuremath{\rightarrow}4{f}^{6}{}^{5}{D}_{0}$ intraconfiguration transition in $\mathrm{Sm}:{\mathrm{SrF}}_{2}$ is forbidden for ${\mathrm{Sm}}^{2+}$ ions in the octahedrally symmetric substitution sites in ${\mathrm{SrF}}_{2}$. We report the direct observation of this transition using laser-induced fluorescence at cryogenic temperatures, and measurements of the excited-state lifetime and the excitation cross section. To the best of our knowledge, this optical transition has the longest-lived excited state ever observed in a solid.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.003 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.032 | 0.004 |
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; both teacher heads agree on what is shown here.
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".