Extending Semiconductor Nanocrystals from the Quantum Dot Regime to the Molecular Cluster Regime
Bibliographic record
Abstract
The size-dependent optical and electronic properties of semiconductor nanocrystal (NC) have been exploited over decades for various applications. This size dependence involves a transition from the regime of bulk colloids of ∼100 nm radius to quantum dots (QDs) of ∼10 nm radius, the details of which are material specific. To understand the transition from the QD regime (∼10 nm) to the molecular cluster regime (∼1 nm) of nanocrystals, we have carefully synthesized a set of CdSe nanocrystals with sizes ranging from 0.89 to 1.66 nm in radius. As the nanocrystals become small, the surface emission strongly increases in amplitude, and the core emission broadens and red-shifts. These effects are rationalized in terms of coupling to ligands via electron transfer theory. The core emission spectra arise from increased vibrational coupling of ligands for very small NC. The surface emission amplitudes arise from a size-dependent surface free energy. The transition from the QD to the molecular cluster regime is found to be at 1.2 nm radius, in contrast to the transition from the bulk to QD transition at the Bohr radius of 5.4 nm in CdSe. These size-dependent surface electronic phenomena may be used for light emission 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 | 0.001 |
| 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".