Low-Temperature Kinetics of Reactions of OH Radical with Ethene, Propene, and 1-Butene
Bibliographic record
Abstract
The kinetics of the reactions of the OH radical with ethene ( k 1 ), propene ( k 2 ), and 1-butene ( k 3 ) are studied over a temperature range of T = 96−296 K. The low-temperature environment is provided by a pulsed Laval nozzle supersonic expansion of nitrogen with admixed radical precursor and reactant gases. The OH radicals are produced by pulsed photolysis of H 2 O 2 at 248 nm. Laser-induced fluorescence of the OH radicals excited in the (1,0) band of the A 2 Σ + −X 2 Π i transition is used to monitor the OH decay kinetics to obtain the bimolecular rate coefficients. At T = 296 K, the rate constants k 1, k 2, and k 3 are also measured as a function of total pressure. The room-temperature falloff parameters are used as the basis for extrapolation of the low-temperature kinetic data, obtained over a limited range of gas number density, to predict the high-pressure limits of all three rate coefficients at low temperatures. The temperature dependence of the measured high-pressure rate constants for T = 96−296 K can be expressed as follows: k 1, ∞ = (8.7 ± 0.7) × 10 -12 ( T /300) (-0.85±0.11) cm 3 molecule -1 s -1; k 2, ∞ = (2.95 ± 0.10) × 10 -11 ( T /300) (-1.06±0.13) cm 3 molecule -1 s -1; k 3, ∞ = (3.02 ± 0.15) × 10 -11 ( T /300) (-1.44±0.10) cm 3 molecule -1 s -1 . All three high-pressure rate constants show a slight negative temperature dependence, which is generally in agreement with both low-temperature and high-temperature kinetic data available in the literature. Implications to the atmospheric chemistry of Saturn are discussed. Incorporating the new experimental data on k 1 in photochemical models of Saturn's atmosphere may significantly increase the predicted rate of photochemical conversion of H 2 O into C−O containing molecules.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".