Picosecond-resolved nonlinear absorption of spin-processible lead sulfide (PbS) nanocrystals from 1100 to 1600 nm
Bibliographic record
Abstract
Solution-synthesized nanocrystals which manifest strong quantum-confinement effects enable size-tunability of spectral properties and strong excitonic effects. Lead sulfide (PbS) nanocrystals are especially interesting for applications in telecommunication because their resonance is tunable to wavelengths from 1.3-1.55 μm and beyond. In other quantum dot systems, optically-induced bleaching of absorption has been shown to lead to a strong nonlinearity in the vicinity of the exciton peak wavelength [1][2-4][5-8]. We report herein results of picosecond-resolved transient absorption in spin-processible solution-synthesized PbS nanocrystals across the wavelength range 1100 nm to 1600 nm. The sample was synthesized using the solution phase organometallic method (hot injection technique), which provides good control over the size of the nanocrystals [9]. The sample consisted of nanocrystals with diameter around 5.2 nm resulting in an exciton peak at 1330 nm. Since the Bohr radius for the bulk PbS is 18 nm, these nanocrystals lay within the strong quantum-confinement regime [10]. Time-resolved absorption was studied using the single-wavelength collinear pump-probe setup. From the observed double-exponential decay trace of the transmission, fast and slow time constants were extracted. The fast component of few 10is of ps was attributed to Auger recombination. The slow component is on the order of ns. The saturation intensity was also measured in this wavelength range using the Z-Scan technique [11]. The open aperture signals were fit to the intensity-dependent absorption model. The value of the saturation intensity was found to be 0.6 GW/cm2 around the exciton peak.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".