Exciton and vibrational dynamics of MAu24(SR)18 (M=Pd, Pt) nanoclusters
Bibliographic record
Abstract
The optical properties of doped metal nanoclusters (NCs) have stimulated great research interests because of their applications in biosensing and photocatalysis. The photoluminescence and excited state dynamics of MAu24(SR)18 are complicated and the detailed mechanism has not been fully understood. Here, we investigate the exciton and vibrational dynamics of two doped NCs MAu24(SR)18 (M=Pd, Pt; SR stands for phenylethanethiolate) by ultrafast spectroscopy. In contrast to the parent Au25(SR)18 NCs, Pd and Pt doping significantly reduce the exciton lifetime by several orders of magnitude. We find that the ultrashort exciton lifetimes of PtAu24 (5 ps) and PdAu24 (30 ps) are ascribed to the ultrasmall energy gap (Eg=0.3 eV). In both two doped NCs, we observe significant coherent vibrations (2.4 THz) that arise from the metal core, which indicates these oscillations can survive regardless of the short exciton lifetime. Unravelling the effect of foreign atom doping on the exciton and vibrational dynamics of metal NCs will provide new insight into their optical properties and help designing these molecular-like nanostructures for specific applications.
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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".