Aggregates and Excitons: Excited-State Behavior of Platinum–Acetylide Two-Photon Chromophore-Doped Ormosil Glasses
Bibliographic record
Abstract
We probe the excited-state dynamics of a platinum–acetylide chromophore dissolved in ormosil glasses in the concentration range of 0.1–400 mM to gain a better understanding of how the environment of the dye reflects upon the overall kinetics observed. At 0.1 mM, ground-state absorption, fluorescence, excited-state absorption (ESA), and triplet ESA reproduce solution behavior. Above ≥10 mM, a weak 485 nm ground-state band appears, consistent with a nominally forbidden S 0 → T 1 transition, and steady-state emission shows quenched fluorescence with enhanced phosphorescence. Following 355 nm flash photolysis, high-concentration samples initially exhibit triplet ESA identical to the 0.1 mM case, but a blue-shifted triplet ESA develops at longer delays; direct excitation of the 485 nm band yields the same blue-shifted spectrum, confirming aggregation effects. Kinetically, the 0.1 mM sample displays a single triplet lifetime, whereas ≥10 mM samples require two. The shorter lifetime at all loadings follows a Freundlich adsorption dependence, consistent with monomer binding to ormosil sites, while the longer lifetime is attributed to aggregation. Ultrafast transient absorption (TA) resolves two ESA bands whose energy separation and relative areas suggest intramolecular exciton coupling between ligand-localized transitions. Fitting the data with exciton theory gives the interligand transition-dipole angle and the excitonic splitting; both evolve with concentration and pump–probe delay, reflecting symmetry breaking, intersystem crossing, and charge-transfer reorganization. At ∼1 mM, the time-dependent band separation is consistent with excimer formation, whereas no excimer signatures are observed at ≥10 mM. These results establish a quantitative structure–dynamics–concentration relationship: aggregation and ormosil-induced microphase separation create coexisting free and aggregated populations that modulate exciton coupling (dipole geometry and splitting) and govern the triplet photophysics.
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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 | 0.001 |
| 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".