Evidence for Solution-State Nonlinearity of sp-Carbon Chains Based on IR and Raman Spectroscopy: Violation of Mutual Exclusion
Bibliographic record
Abstract
Adamantyl-end-capped polyynes with chains of 4, 6, 8, 10, 12, 16, and 20 sp-hybridized carbons (C4-C20) have been synthesized and their IR and Raman spectra obtained. On the basis of violations of the mutual-exclusion principle between IR and Raman spectroscopy, spectral evidence demonstrates that these molecules possess a noncentrosymmetric molecular structure in both the solid and solution states. This premise is supported by X-ray crystallographic analysis of C12, which shows a bent, noncentrosymmetric structure in the solid state. Density functional theory (DFT) calculations for adamantyl-end-capped polyynes, in comparison with those for hydrogen-end-capped polyynes, show that the observed violation of mutual exclusion is independent of the end group of the polyyne chain (i.e., adamantyl versus H). The origin of these experimental spectroscopic observations is ascribed to the existence of dynamic contributions to molecular nonlinearity resulting from low-frequency skeletal bending vibrations of the chains and/or the existence of low-energy bent conformations of the polyyne chains, as DFT-optimized structures seem to suggest.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".