Structures of Water Molecules at the Interfaces of Aqueous Salt Solutions and Silica: Cation Effects
Bibliographic record
Abstract
Structures of water molecules at water/silica interfaces, in the presence of alkali chloride, were investigated using infrared−visible sum frequency vibrational spectroscopy. Significant perturbations of the interfacial water structure were observed on silica surfaces with the NaCl concentration as low as 1 × 10 −4 M. The cations, which interact with the silica surface via electrostatic interaction, play key roles in perturbing the hydrogen-bond network of water molecules at the water/silica interface. This cation effect becomes saturated at concentrations around 10 −2 to 10 −1 M, where the sum frequency generation peaks at 3200 and 3400 cm −1 decrease by 75%. Different alkali cation species (Li +, Na +, and K + ) produce different magnitudes of perturbation, with K + > Li + > Na + . This order can be explained by considering the effective ionic radii of the hydrated cations and the electrostatic interactions between the hydrated cations and silica surfaces. The interfacial water structure associated with the 3200 cm −1 band is more vulnerable to the cation perturbation, suggesting that the more ordered water structure on silica is likely associated with the vincinal silanol groups, which create a higher local surface electrical field on silica.
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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".