Effect of Disorder on the Emission Spectra of Er <sup>3+</sup> , Tm <sup>3+</sup> , and Yb <sup>3+</sup> -Doped β-NaYF <sub>4</sub> : Quantum Chemical and Experimental Results
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Exact optical characteristics of the trivalent lanthanide ions (Ln 3+ ) are crucially determined by their nearest neighbors and in turn govern the quantum efficiency of Ln 3+ -doped upconverting nanoparticles (UCNPs). Their often extremely low quantum efficiency can be increased considerably by doping Ln 3+ into disordered host lattices. In these lattices, each Ln 3+ experiences a slightly different low-symmetry environment, which leads to small variations in its (optical) properties. To this end, we predict crystal field energy levels and oscillator strengths of Er 3+, Tm 3+, and Yb 3+ doped into disordered hexagonal (β-)NaYF 4 and ordered LiYF 4 . In addition, theoretical photoluminescence spectra for β-NaYF 4:Er 3+ were determined. The results were obtained using a wave function-based ab initio computational approach and an embedded cluster model. The disorder of β-NaYF 4:Ln 3+ was accounted for through weighted averaging, in which stochastic considerations and Boltzmann distributions for several local configurations were included. Comparison to experimental and semiempirical data showed particularly good agreement for both the ordered and disordered material. The disordered lattice significantly shifted the crystal field energy levels and changed the oscillator strengths of the respective Ln 3+ transitions. Importantly, the computed photoluminescence spectra showed the best agreement with experimental spectra when including the predicted results of all disordered configurations individually. This reveals that the observed energetic splitting and transition rates of the excited Ln 3+ dopants can only be accurately described if the disorder of the β-NaYF 4 crystal is properly considered. The proposed quantum chemical protocol paves the way for the future simulation of photon upconversion processes in UCNPs.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".