Uptake of Gas-Phase SO<sub>2</sub> and H<sub>2</sub>O<sub>2</sub> by Ice Surfaces: Dependence on Partial Pressure, Temperature, and Surface Acidity
Bibliographic record
Abstract
The uptakes of gas-phase SO 2 and H 2 O 2 by ice surfaces have been investigated at temperatures from 213 to 238 K and from 10 -7 to 10 -4 Torr partial pressure. These experiments have been conducted in a low-temperature, coated-wall flow tube coupled to an electron-impact, quadrupole mass spectrometer which monitors changes in the SO 2 and H 2 O 2 partial pressure. The ice surfaces are formed by freezing liquid water. Unlike the uptakes of strong acids such as HNO 3 and HCl, the SO 2 and H 2 O 2 uptakes are fully reversible on the time scale of the experiment and the surface coverages are roughly a thousandth of a monolayer at 10 -6 Torr partial pressure and 228 K. The SO 2 uptakes scale with the square root of the partial pressure of the SO 2 gas, indicating that dissociation of the hydrated form of adsorbed SO 2 is occurring on the surface. The H 2 O 2 uptakes scale linearly with the H 2 O 2 partial pressure, indicating that dissociation does not occur. The uptakes are driven by H-bond interactions in this case. Support for these conclusions comes from uptake measurements with ice surfaces which were formed by freezing either acidic or basic aqueous solutions. Although the H 2 O 2 uptakes are independent of pH, the acidic ice surfaces considerably inhibit the SO 2 uptake and the basic surfaces enhance the SO 2 uptake. The results in this paper are consistent with atmospheric observations which show that both S(IV) and H 2 O 2 have low retention efficiencies after supercooled cloud droplets freeze, whereas the retention efficiency of HNO 3 is high. The uptakes are sufficiently small that scavenging of SO 2 and H 2 O 2 by ice clouds will not be significant.
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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".