Infrared Absorption and Emission Spectra of Hydrogenated Amorphous Carbon Prepared in the Presence of Oxygen, Nitrogen, Ammonia, and Carbon Monoxide
Bibliographic record
Abstract
The formation of carbonaceous condensates in the atmospheres of asymptotic giant branch (AGB) carbon stars and in the nebulae of post-AGB objects occurs in a chemical environment that also contains oxygen and nitrogen. The extent of incorporation of chemical groups containing these elements in carbonaceous solids will depend on the ratios C/O and C/N. The presence of chemical groups containing O and N can have a significant effect on the infrared spectrum of this material through the introduction of new absorption and emission features and by perturbing spectral lines arising from CH and other hydrocarbon groups. To simulate some aspects of this chemistry, we have prepared samples of hydrogenated amorphous carbon (HAC) containing these elements by laser ablation of graphite in mixed H 2 /N 2 , H 2 /O 2 , and H 2 /CO gases and in NH 3 . Absorption and emission spectra are reported for these materials in the 2.5-20 μm region. We find that the inclusion of oxygen has a profound effect on both 3.4 μm and longer wavelength absorption in HAC even at low concentration. Condensation of HAC in the presence of N 2 , CO, and NH 3 produces changes in the profile and relative intensity of components of the 3.4 μm CH 2, 3 hydrocarbon band, but some of these effects can be reversed by heating to higher temperature. We find that the condensation of a crystalline diamond component is greatly facilitated in the presence of O 2 or NH 3 . A number of sharp spectral features attributable to diamond have been observed in these spectra.
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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".