Ultrafast optical Kerr effect measurements of third-order nonlinearities in cross-conjugated <i>iso</i>-polydiacetylene oligomers
Bibliographic record
Abstract
We present a study on the ultrafast third-order nonlinearities of a novel series of iso-polydiacetylene oligomers (iso-PDAs). Unlike polydiacetylenes that contain a linearly-conjugated backbone, iso-PDAs have a backbone that is cross-conjugated. A new Kerr-gate technique, differential optical Kerr effect (DOKE) detection, is used to measure third-order nonlinear susceptibilities, χ(3), and second hyperpolarizabilities, γ, of monomer, dimer, trimer, pentamer, and heptamer samples in tetrahydrofuran (THF) solutions. A linear increase in γ as a function of the number of repeat units is observed for all samples except the monomer, suggesting that the fixed-length linearly conjugated segments dominate the electronic polarizability. An added increase to the oligomer nonlinearities due to communication along the cross-conjugated path is not observed. The largest nonlinearity was observed in the heptamer sample, displaying a second hyperpolarizability relative to the THF solvent of γheptamer/γTHF=181±9. In addition, an interesting feature arising out of the signal decay tail is present in the samples but absent in our THF solvent reference.
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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) | 0.000 | 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 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".