Raman and Infrared Emission Spectra of Hydrogenated Amorphous Carbon: Insight into the Origin of the 6-14 Micron Infrared Emission Bands
Bibliographic record
Abstract
We have obtained micro-Raman spectra of hydrogenated amorphous carbon (HAC) in particulate and thin-film form. A comparison between Raman and infrared emission spectra of HAC in the 6-14 μm region yields further information concerning the chemical structure of the emitters responsible for the infrared emission bands observed in interstellar and circumstellar sources. In particular, we find that both aromatic and nonaromatic species can contribute to emission at 6.2 μm but that emission in the 7.6-7.8 μm band arises primarily from sixfold aromatic species. Using Raman spectra as a guide, it is suggested that the nanoparticles responsible for the unidentified infrared bands may be three-dimensional, consisting of small stacks of aromatic rings. We find that these particles should emit at wavelengths between 6.17 and 6.25 μm (1620-1600 cm-1), coinciding with those observed in types A and B infrared emission sources. We find that a 6.05 μm satellite to the 6.2 μm feature observed in sources such as HD 44179 likely arises as a result of emission from olefinic CC in bridging groups between polycyclic aromatic hydrocarbon molecules. Infrared emission spectra of HAC films also show features at 6.9 and 7.27 μm corresponding to bending vibrations in aliphatic and olefinic groups. Counterparts of these bands in interstellar emission spectra may be useful in indicating the level of hydrogenation of the emitters.
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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 | 0.001 | 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".