Photosensitization Aspects of Pinacyanol H-Aggregates. Charge Injection from Singlet and Triplet Excited States into SnO<sub>2</sub> Nanocrystallites
Bibliographic record
Abstract
The singlet and triplet excited-state behavior of a symmetric carbocyanine dye, 1,1‘-diethyl-2,2‘-carbocyanine (commonly referred as pinacyanol), adsorbed on SiO 2 and SnO 2 nanocrystallites has been investigated using transient absorption spectroscopy. The adsorption of the dye molecules on the negatively charged SiO 2 or SnO 2 colloids results in H-type aggregation. When excited with a 532 nm laser pulse we observe a short-lived (τ < 30 ps) singlet excited state of the H-aggregate on the SiO 2 surface. In contrast to this observation, a long-lived cation radical formation is seen on the SnO 2 surface. The dependence of the cation radical yield on the concentration of SnO 2 colloids and the intensity of laser pulse excitation confirms direct electron transfer between the excited aggregate and SnO 2 colloids. Both singlet and triplet excited states of the pinacyanol aggregate participate in the charge injection process on the SnO 2 surface with heterogeneous electron-transfer rate constants of >5 × 10 10 and 7 × 10 9 s -1, respectively. Such a charge injection process is also confirmed from the photocurrent generation at a dye-modified SnO 2 electrode. The fast reverse electron transfer between the photoinjected electron and the cation radical of the dye aggregate is considered to be a major limiting factor in achieving high photoconversion efficiencies.
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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".