The electronic spectrum of silicon methylidyne (SiCH), a molecule with a silicon–carbon triple bond in the excited state
Bibliographic record
Abstract
The à 2Σ+–X̃ 2Πi transition of jet-cooled silicon methylidyne, SiCH, has been recorded by laser-induced fluorescence in the 850–600 nm region. The radical was produced in an electric discharge using tetramethylsilane as the precursor. Fifteen cold bands of SiCH and 16 bands of SiCD have been assigned vibrationally, giving the upper state frequencies as v2′=715/558 cm−1 and v3′=1168/1127 cm−1 for SiCH/SiCD. Rotational analysis of the 000 and 303 bands for each isotopomer has given the following molecular structures: r0″(Si–C)=1.692 52(8), r0″(C–H)=1.0677(4), r0′(Si–C)=1.6118(1), and r0′(C–H)=1.0625(5) Å. The silicon–carbon bond length in the X̃ 2Π ground state of SiCH (electron configuration …σ2π3) is typical for a Si=C double bond; in the à 2Σ+ excited state (…σ1π4) it corresponds to a triple bond. This work provides the first experimental measurement of the length of the carbon–silicon triple bond.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".