Photosensitizers Regulate Nitrate Photoproduct Yields in Bulk Aqueous Matrices
Bibliographic record
Abstract
Photolysis of nitrate (NO 3 – ) in the presence of photosensitizers is thought to promote the release of atmospherically important reactive nitrogen species (NO y ), such as HONO, via mechanisms that are poorly understood. To address this knowledge gap, we conducted photochemistry studies on mixtures of NO 3 –, a model photosensitizer [4-benzoylbenzoic acid (4-BBA)], and various aliphatic organic matter proxies. We found that aliphatic organic matter enhances the production of NO y and superoxide (O 2 – ) from bulk aqueous nitrate photolysis, while the addition of 4-BBA decreases NO y and O 2 – yields in most cases. This effect was not observed in heterogeneous systems, where 4-BBA enhanced photochemical NO y production when coadsorbed with NO 3 – on silica surfaces. This demonstrates that photosensitizers act as both oxidants and reductants, regulating the yields of NO y and reactive oxygen species from nitrate photochemistry. Given sufficient residence time in the bulk aqueous phase, nitrate photoproducts can be scavenged via secondary reactions with photosensitizers. In heterogeneous and aerosol systems with high surface area-to-volume ratios, however, volatilization of NO y photoproducts is favored, and NO y production is less affected by chromophoric organic matter sinks in the bulk phase. This work demonstrates the intricate role of aliphatic and chromophoric moieties in natural organic matter in the photochemical conversion of NO 3 – to NO y (i.e., renoxification) in the atmosphere.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.000 | 0.003 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".