Nonthermalized excited states in Ru(II) polypyridyl complexes probed by ultrafast transient absorption spectroscopy with high photon energy excitation
Bibliographic record
Abstract
The picosecond excited state dynamics of a series of homoleptic Ru(II) polypyridyl complexes (where LL = bpy, dmb, dmeob, dfmb, or dttb) have been investigated in aqueous solution at room temperature using femtosecond transient absorption spectroscopy with high photon energy excitation. All of the complexes studied produced similar spectroscopic signatures: a near-instantaneous bleach centered at 470–500 nm corresponding to the static absorption spectrum, as well as an intense absorption (475–650 nm) that decayed within the instrument response function (IRF) to form a broad, low-level absorption extending from 500–650 nm. Detailed analyses of both kinetic and spectral parameters by singular value decomposition (SVD) indicate that the excited state difference spectra contain contributions from at least three distinguishable species that have been assigned as ligand-based π* ← π* and ligand-to-metal-charge-transfer (LMCT) transitions concomitant with the loss of the ground state metal-to-ligand-charge-transfer (MLCT) transition. Kinetic information extracted at 530 nm (an optical marker for the fully intraligand-delocalized 3 MLCT state) or 660 nm (LMCT transitions) appear to be biphasic in some cases with the amplitude of the IRF-limited component becoming larger with shorter wavelength excitation. Further, rise dynamics were observed at redder probe wavelengths for Ru(bpy) 3 2+ and Ru(dttb) 3 2+ . These observations are different from those obtained using lower photon energy excitation and show that excitation wavelength strongly influences the early photophysical events in these Ru(II) complexes.Key words: ruthenium, photophysics, lasers, transient absorption spectroscopy, excited states, singular value decomposition (SVD).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".