A muSR study of the interactions between muoniated radicals and metallic nanoparticles in mesoporous silica hosts
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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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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 | 0.000 | 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) | 0.000 | 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 it