Normal Coordinate Analysis and Vibrational Spectra of Aromatic Carbon Nanostructures
Bibliographic record
Abstract
Theoretical infrared absorption spectra of aromatic ring molecules having up to 102 carbon atoms and with various edge hydrogenations have been obtained using a classic mechanical model and a simplified valence force field. Force constants have been adapted from those available for smaller molecules. Spectral line intensities are calculated in a double harmonic approximation with effective atomic charges obtained using a Hückel tight-binding Hamiltonian. Vibrational modes of clusters of like aromatic ring molecules are obtained through introduction of an interlayer force constant. These modes are predicted to occur in the wavelength range between 80 and 400 μm. We explore the effect of dehydrogenation on these spectra as well as hydrogenation of terminal C atoms in either aromatic or aliphatic form. Many spectra exhibit a quasi-continuum between 6 and 9 μm that arises from the overlap of many vibrational modes in this region. With CH 2 edge groups, we find a new spectral feature near 16 μm and the aliphatic CH 2 symmetric stretch vibration is found to shift from 3.5 to 3.3 μm when these groups are present at terminal sites on aromatic carbon skeletons. The relevance of calculated spectra to those of astronomical sources is briefly discussed.
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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) | 0.003 | 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".