New Infrared Spectra of Acetylene-Water Dimers: First Determination of the <i>A</i> Rotational Constant and Another <i>K</i>-Dependent Anomaly
Bibliographic record
Abstract
Infrared spectra of acetylene–water complexes are studied in the regions of the H 2 O ν 2 bend (1600 cm –1 ) and the D 2 O ν 1 /ν 3 stretches (2670–2808 cm –1 ), using tunable infrared sources to probe a pulsed supersonic slit jet expansion. In the H 2 O bend region, there is a puzzling absence of K a = 0 transitions for C 2 H 2 –H 2 O, while both K a = 0 and 1 are observed for C 2 D 2 –H 2 O. This continues a pattern of “missing” K a states noted in previous infrared studies of acetylene-water. Noticeable line broadening gives estimates of upper state predissociation lifetimes of about 1.6 ns for C 2 D 2 –H 2 O with K a ’ = 1, 0.8 ns for C 2 H 2 –H 2 O with K a ’ = 1, and 0.8 ns for C 2 D 2 –H 2 O with K a ’ = 0. The lifetime for C 2 H 2 –H 2 O K a ’ = 0 must be much shorter (<0.05 ns) since rapid predissociation seems to be the only explanation for its absence in the spectrum. In the D 2 O ν 3 region, clear sub-bands with K a = 0 ← 1, 1 ← 0, and 2 ← 1 are observed which enable a good determination of the A rotational constant of C 2 H 2 –D 2 O (7.313 ± 0.007 cm –1 ), a first for acetylene-water dimer and larger than previously expected.
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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 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".