Kinetic Study of the Reactions of Ground State Atomic Carbon and Oxygen with Nitrogen Dioxide over the 50–296 K Temperature Range
Bibliographic record
Abstract
The kinetics of the reactions of nitrogen dioxide, NO 2, with atomic oxygen and atomic carbon in their ground triplet states ( 3 P) have been studied at room temperature and below using a supersonic flow (Laval nozzle) reactor. O( 3 P) and C( 3 P) atoms (hereafter O and C respectively) were created in situ by the pulsed laser photolysis of the precursor molecules NO 2 at 355 nm and CBr 4 at 266 nm, respectively. While the progress of the O + NO 2 reaction was followed by detecting O atoms by a chemiluminescent tracer method, progress of the C + NO 2 reaction was followed by detecting C atoms directly by vacuum ultraviolet laser-induced fluorescence at 116 nm. The measured rate constants for the O + NO 2 reaction are found to be in excellent agreement with earlier work at higher temperatures and extend the available kinetic data for this process down to 50 K. The present work represents the first kinetics study of the C + NO 2 reaction. Although both reactions display rate constants that increase as the temperature falls, a more substantial rate increase is observed for the O + NO 2 reaction. The effects of these reactions on the simulated abundances of interstellar NO 2 and related compounds were tested using a gas–grain model of the dense interstellar medium, employing expressions for the rate constants of the form, k ( T ) = α( T /300) β, with α = 1 × 10 –11 cm 3 s –1 and β = −0.65 for the O + NO 2 reaction and α = 2 × 10 –10 cm 3 s –1 and β = −0.11 for the C + NO 2 reaction. Although these simulations predict that gas-phase NO 2 abundances are low in dense interstellar clouds, NO 2 abundances on interstellar dust grains are predicted to reach reasonably high levels, indicating the potential for detection of this species in warmer regions.
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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 | 0.001 |
| 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".