The Role of Ions on the Surface-Bound Water Structure at the Silica/Water Interface: Identifying the Spectral Signature of Stability
Bibliographic record
Abstract
We explore the influence of salt addition on the structure of water interacting closely with a charged silica surface. Isolating these surface effects is challenging, even with surface-specific techniques like sum frequency generation (SFG), because of the presence of aligned water nanometers to microns away from the charged silica. Here we combine zeta potential and SFG intensity measurements with the maximum entropy method and reported heterodyne second harmonic and sum frequency generation results to deconvolute from the total signal intensity the SFG spectral contributions of the waters adjacent to the surface. Deconvolution reveals that at very low ionic strength the surface water structure is similar to that of a neutral silica surface near the point of zero charge with waters oriented in opposite directions. This result suggests the known metastability of silica near the PZC and the stability of silica in low ionic strength solutions may originate from the same source, these oppositely oriented surface-bound waters. Orientation changes are induced upon adding salt, which lead to a decrease in the total amount of aligned water at the surface.
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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 | 0.001 |
| 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".