Detection of New Infrared Spectral Features in Hydrogenated Amorphous Carbon
Bibliographic record
Abstract
We have obtained high-resolution (1 cm -1 ) spectra of hydrogenated amorphous carbon (HAC) in both emission and absorption. Deconvolution of these spectra into Gaussian-Lorentzian components reveal two new features at 3098 cm -1 (3.23 μm) and 2890 cm -1 (3.46 μm) attributable to nonaromatic CCH 2 and tertiary CH groups, respectively. In addition, relatively sharp lines (Δν ~ 25 cm -1 ), which we assign to CH 2 groups in cyclohydrocarbon molecules such as hexahydropyrene, appear on heating HAC to 800 K. We propose that these molecules are the precursors of H n polycyclic aromatic hydrocarbons seen in low-excitation protoplanetary nebulae. The profile of the 2890 cm -1 (3.46 μm) tertiary CH feature detected as a component of HAC is very similar to that observed in dark clouds where it has been attributed to interstellar diamond-like material. An absorption/emission feature at 3098 cm -1 (3.23 μm) should also be present in "transition" sources, i.e., regions where the composition of the carbonaceous gas/dust component is evolving from a saturated, CH 2 , CH 3 -rich material to less saturated aromatic material. The role of H atom reaction and UV irradiation in determining spectra in the 2.8-3.7 μm region is briefly discussed. On the basis of our laboratory data we find that the absence of CH 2 , CH 3 absorption in dark clouds can be understood if H atom reactions with HAC are inhibited as a result of an increased rate of gas-phase reactions.
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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) | 0.001 | 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".