A muSR study of the interactions between muoniated radicals and metallic nanoparticles in mesoporous silica hosts
Bibliographic record
Abstract
Transverse field (TF-muSR) and Avoided level crossing resonance (ALCR) techniques have been used in this very first investigation on the structure and dynamics of the Mu-cyclohexadienyl (MuC₆H₆) radical interacting with Au and Pt metal nanoparticles supported in mesoporous silica (SBA-15), providing novel information about the interactions of radicals with silica environments. Two different loadings of benzene were investigated by the TF-μSR and its companion Fast Fourier Transform (FFT) technique, revealing that the observed radicals are shielded from the metallic nanoparticle surfaces probably by a layer of benzene coating. At lower loading, the adsorption of benzene on nanoparticles increases the opportunity of an encounter between the muonium and benzene near the NP surface. The ALCR Δ₁ resonance arising from hyperfine anisotropy is observable in MNP-loaded samples up to 418 K but not in the unloaded SBA-15, while towards lower temperature it is the Δ₀ resonance mainly from isotropic hyperfine interactions that is observed in the small gold nanoparticle loaded SBA-15 sample. Such an difference is attributed to the stronger binding of MuC₆H₆ to the benzene coated MNPs than silica nanopore surfaces, so it is less perturbed by the surrounding atoms. Different dynamic behaviors have been seen in MCM-41 silica host compared to SBA-15, which is thought due to the agglomeration of benzene in the smaller pore sizes. In fact, the dynamics in this case are more like that seen for small Au NP-loaded SBA-15, giving an environment closer to that of liquid benzene due to this agglomeration. Disappointingly, the isotropic hyperfine coupling constants, determined from the positions of the Δ₀ and Δ₁ resonances, are almost the same in the MNP-loaded and unloaded samples, implying that the electronic structure of MuC₆H₆ is only weakly perturbed by the presence of the MNPs from an indirect interaction between MuC₆H₆ and the MNP. The only information on a direct interaction comes from the temperature-dependent longitudinal field T₁ relaxation rates at a monolayer benzene loading, giving also a clear direction for relevant future studies.
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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".