Multiple Photochemical Processes in Liquid Crystalline Azo Dye-Doped Liquid Crystals
Bibliographic record
Abstract
We present a detailed study on the multiple photochemical processes that can occur in a nematic liquid crystal (BL006) doped with a liquid crystalline azobenzene compound (LC azo dye) as a result of the photoinduced isomerization of the chromophore. On the basis of the photo-optical response (transmittance change upon illumination) and the electro-optical response (transmittance change upon application of a voltage) as well as polarizing microscopic observations, two regimes of behaviors can be distinguished upon UV exposure inducing the trans−cis isomerization. In the regime of low LC azo dye concentrations (≲ 7 wt %), where the achievable amount of cis isomers are miscible with the LC host, only a photochemical disordering of the LC takes place at room temperature, with a precisely controllable degree of disordering. At elevated temperatures, but below the clearing temperature T ni of the LC, the photochemical disordering can lead to the photochemical nematic−isotropic phase transition. In the regime of high LC azo dye concentrations, when the amount of cis isomers passes a certain concentration, they become immiscible with the LC, which triggers a photochemical phase separation process. Depending on the rate at which cis isomers are formed, the phase separation process can either follow the disordering or appear simultaneously with and compete against the disordering and the nematic−isotropic phase transition. In all cases, the mixture evolves over time toward two separated LC phases, with one disordered rich in cis isomer. All these photochemical processes under UV light can be reversed by visible light inducing the cis−trans back-isomerization of the chromophore. This study shows the richness of the photo-optical and electro-optical behaviors of LC azo dye-doped liquid crystals and provides a comprehensive understanding on the multiple reversible photochemical processes.
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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) | 0.001 | 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".