Low Density Interior in Supercooled Aqueous Nanodroplets Expels Ions to the Subsurface
Bibliographic record
Abstract
The location of a single and multiple ions in aqueous droplets plays a key role in chemical reactivity of atmospheric and man-made aerosols. We report direct computational evidence that in supercooled aqueous nanodroplets a lower density core of tetrahedrally coordinated water molecules expels the sodium ions to a higher density and more disordered subsurface. In contrast, at ambient temperature the single Na+ density is higher in the core region and has a broad maximum at the droplet's center of mass. We analyse the expulsion of a single ion in terms of a general reference electrostatic model that we have developed. The energy of the system in the analytical model is expressed as the sum of electrostatic and surface energy of a fluctuating droplet. The model predicts that the energy associated with the distance of the ion from the droplet's center of mass is quadratic in this distance. We name thiseffect "electrostatic confinement". The predictions of the model are consistent with the simulations fndings for a single Na+ ion at ambient conditions. Our results assist in understanding the mechanisms of charging of macromolecules in spray-based ionization methods used in native mass spectrometry and the physical chemistry of atmospheric aerosols.
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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 | 0.001 | 0.001 |
| Open science | 0.001 | 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".