Photooxidation of Atmospheric Alcohols on Laboratory Proxies for Mineral Dust
Bibliographic record
Abstract
We have used a novel photochemical Knudsen cell reactor to investigate the uptake and phototransformation of some atmospherically important trace organics on TiO(2) and TiO(2)-SiO(2) mixed films. Illumination of TiO(2) films led to an enhanced uptake of isopropanol and n-propanol and the concurrent production of gas-phase acetone and propionaldehyde, respectively, with high efficiency. Acetone production from isopropanol on illuminated TiO(2) films displayed a significant enhancement in the presence of cosorbed AgNO(3) or KNO(3). Uptake of cyclohexene by TiO(2) films required the presence of both nitrate anion and light. The wavelength and substrate (TiO(2) vs SiO(2)) dependence of the nitrate-induced enhancement in uptake indicates that it was not caused by direct photolysis of nitrate anion. We propose a 2-fold role for nitrate anion in the present experiments: first, as an electron trapping agent that activates the TiO(2) surface toward photooxidation; second, as suggested by our results for cyclohexene, as a source of reactive nitrate radical at the TiO(2) surface. These observations suggest that mineral dust containing photoactive components may catalyze the transformation of photochemically inactive organic compounds into species that absorb in the actinic region.
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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".