Distinguishing disorder-induced bands from allowed Raman bands in graphite
Bibliographic record
Abstract
The nature of the D band in the Raman spectrum of graphite has been the subject of considerable discussion. We examine the relationship between the depolarization characteristics of the D, ${D}^{\ensuremath{'}},$ and G fundamentals and their corresponding overtones and combinations on the basal and damaged edge planes of highly oriented pyrolytic graphite in the range 800--4800 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. A clear distinction is found between the depolarization ratios of bands that are Raman allowed $(2D,$ ${2D}^{\ensuremath{'}},$ $2D+G)$ and those that are disorder induced $(D,$ ${D}^{\ensuremath{'}},$ $D+G),$ implying that they are dictated by whether a Raman band is allowed in the infinite crystal, rather than by the bands' symmetry, as derived from previously proposed assignments of the D and G bands. Furthermore, although the ${D}_{a/b}$ vs ${2D}_{a/b}$ intensity ratios could differ considerably (where $a/b=HH/VV,$ $HV/VV),$ the participation of a G phonon in the scattering process changes their value in the same amount, i.e., ${D}_{a/b}{/D+G}_{a/b}\ensuremath{\approx}{2D}_{a/b}{/2D+G}_{a/b}.$ Such a simple result is surprising in view of the complexity of multiphonon scattering that involves several coupled scattering events.
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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 | 0.001 | 0.001 |
| 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".